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ARDX US Equity

Ardelyx, Inc.Health Care · Pharmaceutical Preparations · CIK 1437402 · FY ends Dec 31
$4.03
+0.11 (+2.81%)
USD · as of 2026-08-19 · marketstack

ARDX · 10-K · period ended 2021-12-31

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filed 2022-02-28 · EDGAR original ↗

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ardx-20211231

Table of Contents

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

____________________________________________________

FORM10-K

____________________________________________________

(Mark One)

FOR THE FISCAL YEAR ENDEDDECEMBER 31, 2021

OR

FOR THE TRANSITION PERIOD FROM TO

COMMISSION FILE NUMBER001-36485

____________________________________________________

ARDELYX, INC.

(EXACT NAME OF REGISTRANT AS SPECIFIED IN ITS CHARTER)

____________________________________________________

(STATE OR OTHER JURISDICTION OF (I.R.S. EMPLOYER

INCORPORATION OR ORGANIZATION) IDENTIFICATION NO.)

400 FIFTH AVE.,SUITE 210,WALTHAM,MASSACHUSETTS02451

(ADDRESS OF PRINCIPAL EXECUTIVE OFFICES, INCLUDING ZIP CODE)

(510)745-1700

(REGISTRANT’S TELEPHONE NUMBER, INCLUDING AREA CODE)

____________________________________________________

Securities registered pursuant to Section 12(b) of the Act:

Title of Each Class Trading Symbol(s) Name of Each Exchange on Which Registered

Common Stock, par value $0.0001 per share ARDX The Nasdaq Global Market

Securities registered pursuant to Section 12(g) of the Act: None

____________________________________________________

Indicate by check mark if the Registrant is a well-known seasoned issuer, as defined in Rule 405 of the Securities Act. Yes oNox

Indicate by check mark if the Registrant is not required to file reports pursuant to Section 13 or 15(d) of the Act. Yes oNox

Indicate by check mark whether the Registrant: (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Actof 1934 during the preceding 12 months (or for such shorter period that the Registrant was required to file such reports), and (2) has been subjectto such filing requirements for the past 90 days.YesxNoo

Indicate by check mark whether the Registrant has submitted electronically every Interactive DataFile required to be submitted pursuant to Rule 405 of Regulation S-T (§232.405 of this chapter) during the preceding 12 months (or forsuch shorter period that the Registrant was required to submit such files).YesxNoo

Indicate by check mark whether the Registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company or an emerging growth company. See the definition of “large accelerated filer”, “accelerated filer”, “smaller reporting company” and “emerging growth company” in Rule 12b-2 of the Exchange Act.

Large accelerated filer x Accelerated filer o

Non-accelerated filer o Small reporting company o

Emerging growth company o

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act.o

Indicate by check mark whether the registrant has filed a report on and attestation to its management’s assessment of the effectiveness of its internal control over financial reporting under Section 404(b) of the Sarbanes-Oxley Act (15 U.S.C. 7262(b)) by the registered public accounting firm that prepared or issued its audit report.x

Indicate by check mark whether the Registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act). YesoNox

The aggregate market value of the Registrant’s common stock held by non-affiliates of the Registrant as of the last business day of the Registrant’s most recently completed second fiscal quarter, June 30, 2021, based on the last reported sales price of the Registrant’s common stock on the Nasdaq Global Market of $7.58 per share was $768,831,274.

The number of shares of Registrant’s Common Stock outstanding as of February 23, 2022, was130,294,254.

DOCUMENTS INCORPORATED BY REFERENCE:

Portions of the Registrant’s Definitive Proxy Statement for its 2022 Annual Meeting of Stockholders, which will be filed with the Commission within 120 days of December 31, 2021, the close of the Registrant’s 2021 fiscal year, are incorporated by reference into Part III of this Report.

Table of Contents

ARDELYX, INC.

FORM 10-K FOR THE FISCAL YEAR ENDED December 31, 2021

TABLE OF CONTENTS

Page

PART I

Item 1. Business 3

Item 1A. Risk Factors 18

Item 1B. Unresolved Staff Comments 52

Item 2. Properties 52

Item 3. Legal Proceedings 52

Item 4. Mine Safety Disclosures 53

PART II

Item 6. [Reserved] 54

Item 7A. Quantitative and Qualitative Disclosures About Market Risk 67

Item 8. Financial Statements and Supplementary Data 69

Item 9A. Controls and Procedures 102

Item 9B. Other Information 104

Item 9C. Disclosure Regarding Foreign Jurisdictions that Prevent Inspection 104

PART III

Item 10. Directors, Executive Officers and Corporate Governance 105

Item 11. Executive Compensation 105

Item 14. Principal Accounting Fees and Services 105

PART IV

Item 15. Exhibits, Financial Statement Schedules 106

NOTE REGARDING FORWARD-LOOKING STATEMENTS

Unless the context requires otherwise, in this Annual Report on Form 10-K the terms “Ardelyx”, “we,” “us,” “our” and “the Company” refer to Ardelyx, Inc.

This Annual Report on Form 10-K contains forward-looking statements that involve risks and uncertainties. Any statements contained herein that are not statements of historical facts may be deemed to be forward-looking statements. In some cases, you can identify forward-looking statements by terminology such as “aim,” “anticipate,” “assume,” “believe,” “continue,” “could,” “due,” “estimate,” “expect,” “goal,” “intend,” “may,” “objective,” “plan,” “predict,” “potential,” “positioned,” “seek,” “should,” “target,” “will,” “would,” and other similar expressions that are predictions of or indicate future events and future trends, or the negative of these terms or other comparable terminology. These forward-looking statements include, but are not limited to, statements about:

•our expectations regarding our plans to commence the commercialization of IBSRELA® (tenapanor) in the U.S. for the treatment of irritable bowel syndrome with constipation (“IBS-C”) in April 2022;

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•our expectations regarding the timing of our receipt of a decision from the Office of New Drugs (“OND”) with respect to our appeal of the Appeal Denied Letter (“ADL”) received from the Office of Cardiology, Hematology, Endocrinology and Nephrology (“OCHEN”) of the United States ("U.S.) Food and Drug Administration (“FDA”) relating to our New Drug Application (“NDA”) for tenapanor for the control of serum phosphorus in adult patients with chronic kidney disease (“CKD”) on dialysis (the “Hyperphosphatemia Indication”);

•our expectations regarding our plans for our participation in the commercialization of XPHOZAH® (tenapanor) for the control of serum phosphorus in adult patients with CKD on dialysis in the U.S., if approved;

•our expectations regarding our Japanese collaboration partner’s plans to file a marketing authorization application with the Japanese Pharmaceuticals and Medical Devices Agency (“PMDA”) in the second half of 2022;

•our expectations regarding the potential market size and the size of the patient populations for IBSRELA and XPHOZAH;

•our plans with respect to RDX013 and RDX020;

•the implementation of our business model and strategic plans for our business, product candidates and technology;

•estimates of our expenses, future revenue, capital requirements, our needs for additional financing and our ability to obtain additional capital;

•our financial performance; and

•developments and projections relating to our competitors and our industry.

Factors that could cause actual results or conditions to differ from those anticipated by these and other forward-looking statements include those more fully described in the “ITEM 1A. RISK FACTORS” section and elsewhere in this Annual Report on Form 10-K. Except as required by law, we assume no obligation to update any forward-looking statement publicly, or to revise any forward-looking statement to reflect events or developments occurring after the date of this Annual Report on Form 10-K, even if new information becomes available in the future. Thus, you should not assume that our silence over time means that actual events are bearing out as expressed or implied in any such forward-looking statement.

SUMMARY OF PRINCIPAL RISKS ASSOCIATED WITH OUR BUSINESS

•We have a limited operating history, have incurred significant losses since our inception and will incur losses in the future, which makes it difficult for us to assess our future viability.

•Although our financial statements have been prepared on a going concern basis, our current level of cash and investments alone is not sufficient to meet our operating plans for the next twelve months, raising substantial doubt regarding our ability to continue as a going concern.

•We will require substantial additional financing to achieve our goals, including our goals of commercializing IBSRELA beginning in April 2022 and pursuing a formal dispute resolution (“FDR”) process in response to the CRL received from the FDA relating to our NDA for tenapanor for the Hyperphosphatemia Indication and the inability to access necessary capital when needed on acceptable terms, or at all, could force us to delay, limit, reduce or terminate our efforts to commercialize IBSRELA or to seek and obtain tenapanor for the Hyperphosphatemia Indication.

•Our failure to meet the continued listing requirements of The Nasdaq Global Market ("Nasdaq") could result in a de-listing of our common stock. On February 28, 2022, we received a letter from Nasdaq indicating that we have failed to comply with the minimum bid price requirement of Nasdaq Listing Rule 5550(a)(2). Nasdaq Listing Rule 5550(a)(2) requires that companies listed on the Nasdaq Capital Market maintain a minimum closing bid price of at least $1.00 per share. Under Nasdaq Listing Rule 5810(c)(3)(A), we have a 180 calendar day grace period to regain compliance by meeting the continued listing standard. To regain compliance, the closing bid price of the Company’s common stock must meet or exceed $1.00 per share for a minimum of ten consecutive business days during this grace period. We are monitoring the bid price of our common stock and will consider options available to us to achieve compliance. There can be no assurances that we will be successful in restoring our compliance with the Nasdaq listing requirements.

•We have never generated any revenue from product sales and may never be profitable.

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•We are substantially dependent on the successful launch and commercialization of IBSRELA for IBS-C, and there is no guarantee that we will achieve sufficient market acceptance for IBSRELA; secure adequate coverage and reimbursement for IBSRELA; or generate sufficient revenue from product sales of IBSRELA .

•Our success is also dependent upon our ability to obtain regulatory approval for tenapanor for the control of serum phosphorus in adult patients with CKD on dialysis, and there can be no assurances that we will be successful in obtaining such regulatory approval.

•Even if we are successful in obtaining regulatory approval for tenapanor for control of serum phosphorus in adult patients with CKD on dialysis, the expense and time required to do so could adversely impact our ability to successfully commercialize XPHOZAH for the Hyperphosphatemia Indication.

•IBSRELA, and/or XPHOZAH, if approved and commercialized, may cause undesirable side effects or have other properties that could limit the commercial success of the product.

•We have no prior experience in the marketing, sale and distribution of pharmaceutical products; and there are significant risks in building and managing a sales organization.

•Third-party payor coverage and reimbursement status of newly-commercialized products are uncertain. Failure to obtain or maintain adequate coverage and reimbursement for IBSRELA and XPHOZAH, if approved, could limit our ability to market those products and decrease our ability to generate revenue.

•We rely completely on third parties to manufacture IBSRELA, XPHOZAH and RDX013. If they are unable to comply with applicable regulatory requirements, unable to source sufficient raw materials, experience manufacturing or distribution difficulties or are otherwise unable to manufacture sufficient quantities to meet demand, our commercialization of IBSRELA, and XPHOZAH, if approved and commercialized, and our development efforts for tenapanor or RDX013 may be materially harmed.

•Our operating activities may be restricted as a result of covenants related to the indebtedness under our loan and security agreement and we may be required to repay the outstanding indebtedness in an event of default, which could have a materially adverse effect on our business.

NOTE REGARDING TRADEMARKS

ARDELYX®, IBSRELA®, and XPHOZAH® are trademarks of Ardelyx. All other trademarks, trade names and service marks appearing in this Annual Report on Form 10-K are the property of their respective owners.

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ITEM 1. BUSINESS

Company Overview

We are a biopharmaceutical company founded with a mission to discover, develop and commercialize innovative first-in-class medicines that meet significant unmet medical needs. This includes adult patients with irritable bowel syndrome with constipation (“IBS-C”), adult patients with chronic kidney disease (“CKD”) on dialysis suffering from elevated serum phosphorus, or hyperphosphatemia; and adult patients with CKD and/or heart failure with elevated serum potassium, or hyperkalemia.

Since commencing operations in October 2007, substantially all our efforts have been dedicated to our research and development (“R&D”) activities, including developing tenapanor and developing our proprietary drug discovery and design platform. We have not generated any revenues from product sales. As of December 31, 2021, we had an accumulated deficit of $712.9 million.

We expect to continue to incur substantial operating losses for the foreseeable future as we prepare for commercialization of IBSRELA®(tenapanor) in April of this year, seek to gain approval for XPHOZAH® (tenapanor) for the control of serum phosphorus in adult patients with CKD on dialysis; prepare for the potential commercialization of XPHOZAH, if approved; incur manufacturing and development cost for, tenapanor; and incur development costs for RDX013. To date, we have funded our operations from the sale and issuance of common stock and convertible preferred stock, funds from our collaboration partnerships, which includes license fees, milestones and product supply revenue, as well as funds from our loan agreements with our lenders.

Our Product Pipeline

IBSRELA for IBS-C

Our unique discovery platform and deep understanding of the primary mechanism of sodium transport in the intestine resulted in our discovery and development of IBSRELA, a first-in-class, FDA approved, sodium hydrogen exchanger 3 ("NHE3") inhibitor for the treatment of IBS-C in adults. IBSRELA acts locally in the gut and is minimally absorbed. By inhibiting NHE3, IBSRELA exerts a triple action mechanism. First, it blocks dietary sodium absorption, leading to increased intestinal transit time and softer stool to address constipation. Second, it decreases intestinal permeability to reduce abdominal pain, and, third, it decreases visceral hypersensitivity to reduce abdominal pain. The triple action mechanism of IBSRELA is differentiated from existing therapies and has been shown to provide significant improvement in abdominal pain, bloating, and constipation – with a quick onset of action and sustained efficacy. In clinical trials, treatment with IBSRELA has been demonstrated to result in improved quality of life versus placebo and patient treatment satisfaction.

We plan to launch IBSRELA in the U.S. in April 2022.

IBS-C is a gastrointestinal disorder characterized by both abdominal pain and altered bowel movements, estimated to affect 11 million people in the U.S. IBS-C is associated with significantly impaired quality of life, reduced productivity, and substantial economic burden. The introduction of new agents over the last decade has led to an established prescription ("RX") treated market with 9,000 writers accounting for 50% of the RXs. Despite the active use of GCC agonist therapies, 83% of Health Care Providers ("HCPs") report a significant unmet need for new therapies, and report that approximately 35% of the patients currently under their care do not adequately respond to the available treatments. When presented with the IBSRELA product profile, 75% of HCPs respond favorably, with the efficacy profile and novel method of action rated as the most compelling aspects of the product profile.

In preparation for our commercial launch of IBSRELA, we have built a commercial organization highly experienced in launching novel therapies into specialty areas. The established nature of the market, limited number of players, concentration of prescribers, recognized unmet need, and favorable response to the novel mechanism IBSRELA product profile enable a targeted promotional effort centered on the 9,000 health care providers that account for 50% of IBS-C prescriptions. Central to the go to market strategy is a highly experienced specialty sales force, many with existing relationships across their GI target base, full company engagement, and innovative peer-to-peer and digital initiatives leveraging the rapidly evolving market dynamics in how HCPs receive information and interact with industry.

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With a concentrated promotional focus on patients currently being managed for IBS-C by high writing HCPs - in contrast to the DTC centered, market building approach taken by the existing GCC agonists - competition for IBSRELA will come largely from the four prescription products indicated for IBS-C: Linzess (linaclotide); Amitiza (lubiprostone); Trulance (plecanatide) and Zelnorm (tegaserod). Additionally, over the counter products are commonly used to treat the constipation component of IBS-C, both alone, and in combination with the IBS-C indicated RX therapies.

We have established commercial agreements with Shanghai Fosun Pharmaceutical Industrial Development Co. Ltd. (“Fosun Pharma”) in China and Knight Therapeutics, Inc. (“Knight”) in Canada for IBSRELA for IBS-C. Knight is currently marketing IBSRELA in Canada.

Development Candidate XPHOZAH: A New Approach for The Control of Serum Phosphorus in Adult Patients with CKD on Dialysis

XPHOZAH is a first-in-class medicine being developed for the control of serum phosphorus in adult patients with CKD on dialysis. XPHOZAH has a unique mechanism of action and acts locally in the gut to inhibit NHE3. This results in the tightening of the epithelial cell junctions, thereby significantly reducing paracellular uptake of phosphate, the primary pathway of phosphate absorption. If approved, XPHOZAH would be the first therapy for phosphate management that blocks phosphorus absorption at the primary site of uptake. It is not a phosphate binder.

In June 2020, we submitted a new drug application ("NDA") to the U.S. Food and Drug Administration (“FDA”) for tenapanor for the control of serum phosphorus in adult patients with CKD on dialysis. The NDA was supported by three Phase 3 trials involving over 1,000 adult patients that evaluated the use of tenapanor for the control of serum phosphorus in adult patients with CKD on dialysis, with two trials evaluating tenapanor as monotherapy and one trial evaluating tenapanor as part of a dual mechanism approach with phosphate binders. All three Phase 3 trials met their primary and key secondary endpoints.

On July 28, 2021, we received a Complete Response Letter ("CRL") from the FDA’s Division of Cardiology and Nephrology (the “Division”) regarding our NDA for tenapanor for the control of serum phosphorus in adult patients with CKD on dialysis. According to the CRL, while the Division agrees “that the submitted data provide substantial evidence that tenapanor is effective in reducing serum phosphorus in adult patients with CKD on dialysis,” the Division characterizes the magnitude of the treatment effect as “small and of unclear clinical significance.” Following an End-of-Review Type A meeting (“End of Review Meeting”) in October 2021, with the Division, we submitted a Formal Dispute Resolution Request (“FDRR”) in December 2021 to the Office of Cardiology, Hematology, Endocrinology and Nephrology (“OCHEN”). The FDRR was focused on demonstrating that the data submitted in the NDA supported the clinical significance of the treatment effect of tenapanor.

On February 4, 2022, we received an Appeal Denied Letter (“ADL”) from OCHEN. On February 18, 2022, we submitted an appeal of the ADL to the FDA’s Center for Drug Evaluation and Research, Office of New Drugs (“OND”). If accepted, we expect a decision on the appeal to the OND in April 2022. While the CRL noted that in order for the NDA to be approved, we need to conduct an additional adequate and well-controlled trial demonstrating a clinically relevant treatment effect on serum phosphorus or an effect on the clinical outcome thought to be caused by hyperphosphatemia in adult patients with CKD on dialysis, the ADL provided a potential additional path forward involving the resubmission of the NDA (without conducting an additional trial) with a number of new analyses of each of our Phase 3 clinical trials; an assessment of tenapanor’s benefits and risks; and a proposal of how to label tenapanor for prescribers. There can be no assurances that the Formal Dispute Resolution (“FDR”) process will result in approval of our NDA, or in a clear path to resubmission of our NDA that is achievable in terms of clinical endpoints, time and cost.

RDX013 Program: Small Molecule for Treating Hyperkalemia

We are also advancing a small molecule potassium secretagogue program, RDX013, for the potential treatment of hyperkalemia. Hyperkalemia is a common problem in patients with heart and kidney disease, particularly in patients taking customary blood pressure medications known as renin-angiotensin-aldosterone system (“RAAS”) inhibitors. RDX013 is a novel mechanism agent designed to target the underlying biological mechanisms of potassium secretion to lower elevated potassium. While currently available therapies are all ion exchange agents, RDX013 is a first in class secretagogue with demonstrated proof of concept in a Phase 2 dose ranging study evaluating the safety and pharmacodynamics of RDX013 in adult patients with hyperkalemia. The next steps for RDX013 will be determined based on final analyses of the Phase 2 results, continued formulation development, and sufficient financial resources.

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RDX020 Program: Small molecule for Treating Metabolic Acidosis

We have an ongoing discovery program targeting the inhibition of bicarbonate exchange inhibitor for the treatment of metabolic acidosis, a highly prevalent comorbidity in CKD patients that is strongly correlated with disease progression and adverse outcomes. We have identified lead compounds that are potent, selective and proprietary inhibitors of bicarbonate secretion. Our research organization was eliminated as part of our October 2021 restructuring, and therefore, we currently expect to continue to advance this discovery program utilizing third-party resources managed by internal non-clinical expertise.

Our Commercial Strategy

We have developed a portfolio of novel products to address unmet medical needs across gastrointestinal and cardiorenal therapeutic areas and intend to commercialize our products in the United States. We have established a high-quality commercial organization highly experienced in bringing novel products to our customers, including patients, payors and healthcare providers. Our commercial capabilities, including marketing, access, patient services and sales are designed to support our commercialization of IBSRELA, and will enable the commercialization of XPHOZAH, if approved. We have executed ex-U.S. collaborations with established industry leaders to efficiently bring XPHOZAH for hyperphosphatemia and IBSRELA for IBS-C to adult patients in specific territories outside of the Unites States.

We continue to evaluate our strategy for the commercialization of IBSRELA and XPHOZAH in other ex-U.S. territories.

Collaboration Partners

We have exclusive rights to tenapanor in the U.S. and we have established agreements with Kyowa Kirin Co., Ltd. ("KKC”) in Japan, Fosun Pharma in China and Knight in Canada for the development and commercialization of tenapanor for certain indications in their respective territories.

Knight has exclusive rights for the development, commercialization and distribution of tenapanor in Canada for hyperphosphatemia and IBS-C. In March 2021, Knight announced the commercial availability of IBSRELA in Canada, following its approval by Health Canada in April 2020. Under the terms of the agreement with Knight, we received a$2.3 million nonrefundable, one-time upfront payment in March 2018 and are eligible to receive additional development and commercialization milestone payments worth up to $17.4 million. We are also eligible to receive royalties throughout the term of the agreement, and a transfer price for manufacturing services.

KKC has exclusive rights for the development, commercialization and distribution of tenapanor in Japan for cardiorenal indications. In April 2021, we announced that KKC had commenced four phase 3 clinical trials in Japan evaluating tenapanor for hyperphosphatemia. The phase 3 clinical trials consist of a multi-center, randomized, double-blind, placebo-controlled, parallel-group comparative study; a phosphate binder-combination parallel-group comparative study; an open-label, single-arm study evaluating adult hyperphosphatemia patients on peritoneal dialysis; and a long-term study evaluating serum phosphorus in adult patients who switch from one or more phosphate binders to tenapanor. KKC has publicly announced its plans to file a marketing authorization application with the Japanese Pharmaceuticals and Medical Devices Agency (“PMDA”) in the second half of 2022. Under the terms of the agreement with KKC, we received a $30.0 million upfront payment from KKC, and we may be entitled to receive up to$55.0 million in total development milestones, of which $10.0 million has been received and recognized as revenue as of December 31, 2021, and approximately ¥8.5 billion for commercialization milestones, or approximately $73.9 million at the currency exchange rate on December 31, 2021, as well as high-teen royalties on net sales throughout the term of the agreement.

Fosun Pharma has exclusive rights for the development and commercialization for the development, commercialization and distribution of tenapanor in China for both hyperphosphatemia and IBS-C. Under the terms of the Fosun Agreement, we received $12.0 million in upfront license, and we may be entitled to additional development and commercialization milestones of up to $110.0 million, as well as reimbursement of cost plus a reasonable overhead for the supply of product and tiered royalties on net sales ranging from the mid-teens to 20%.

Corporate Restructurings

On July 29, 2021, our Board of Directors approved, and on August 2, 2021, we began implementing a restructuring plan to better align our workforce and anticipated commercial and development spend with our capital resources and the needs of our business following the receipt of the CRL for tenapanor for the control of serum phosphorus in adult patients with CKD on dialysis. Under the restructuring plan, we reduced our workforce by 83 employees (approximately 33%). Impacted employees

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received cash payments equal to their base pay for a notice period of sixty (60) days and Company funded COBRA premiums through such notice period.

Following the conclusion of our End of Review Meeting with the FDA, in October 2021, we began to implement an additional restructuring plan to further reduce operating costs and better align our workforce with the needs of our business. Under the restructuring plan, we planned to reduce our workforce by approximately 100 of our remaining employees (approximately 60%). The impacted employees received notice that their positions would be eliminated on December 15, 2021.

On November 30, 2021, we announced plans to launch IBSRELA, our approved treatment for IBS-C in adults. In connection with the planned launch of IBSRELA, which we currently expect to occur in April 2022, we retained 28 of the employees whose positions were originally planned to be eliminated as part of the restructuring plan, thereby reducing the number of employees impacted by the restructuring plan to 72. The restructuring plan, which resulted in the elimination of our research organization was substantially completed in December 2021.

Employees who were impacted by the restructurings were eligible to receive severance benefits and Company funded COBRA premiums, contingent upon an impacted employee’s execution (and non-revocation, where applicable) of a separation agreement, which included a general release of claims against us. In connection with the restructurings, we have incurred restructuring charges of $6.2 million, which were recorded during the twelve months ended December 31, 2021, related to one-time employee termination benefits, including severance payments and other employee-related costs. Of these charges, $2.7 million was recorded in research and development expenses, and $3.5 million was recorded in general and administrative expense in the accompanying statements of operations and comprehensive loss. Most of the cash payments related to the reduction in workforce were disbursed during the twelve months ended December 31, 2021. We have reported the remaining estimated liability of $0.5 million as accrued compensation and benefits in our Balance Sheet as of December 31, 2021.

CORPORATE DEVELOPMENT

In July 2020, we filed a Form S-3 registration statement, which became effective in August 2020, containing (i) a base prospectus for the offering, issuance and sale by us of up to a maximum aggregate offering price of $250.0 million of our common stock, preferred stock, debt securities, warrants and/or units, from time to time in one or more offerings; and (ii) a prospectus supplement for the offering, issuance and sale by us of up to a maximum aggregate offering price of $100.0 million of our common stock that may be issued and sold, from time to time, under an Open Market Sales Agreement with Jefferies LLC, as sales agent, deemed to be “at-the-market offerings” (the "2020 Open Market Sales Agreement"). Pursuant to the 2020 Open Market Sales Agreement, Jefferies, as sales agent, received a commission of up to 3.0% of the gross sales price for shares of common stock sold under the 2020 Open Market Sales Agreement. We sold a cumulative total of 23.3 million shares and received gross proceeds of $100.0 million at a weighted average sales price of approximately $4.30 per share under the 2020 Open Market Sales Agreement.

In August 2021, we filed an additional prospectus supplement under the Registration Statement for the offering, issuance and sale by us of up to a maximum aggregate offering price of $150.0 million of our common stock that may be issued and sold, from time to time, under an additional sales agreement we entered into with Jefferies (the "2021 Open Market Sales Agreement"), pursuant to which we may, from time to time, sell up to $150.0 million in shares of our common stock through Jefferies. We are not required to sell shares under the 2021 Open Market Sales Agreement. Pursuant to the 2021 Open Market Sales Agreement, Jefferies, as our sales agent, receives a commission of up to 3.0% of the gross sales price for shares of common stock sold under the 2021 Open Market Sales Agreement. As of December 31, 2021, we have sold 15.7 million shares and received gross proceeds of $25.0 million at a weighted average sales price of approximately $1.60 per share under the 2021 Open Market Sales Agreement.

In December 2019, we completed an underwritten public offering of 23.0 million shares of common stock, resulting in the receipt of aggregate gross proceeds of approximately $143.8 million, less underwriting discounts, commissions and offering expenses totaling approximately $8.9 million, which resulted in net proceeds of approximately $134.9 million.

In November 2019, we enhanced our strategic partnership with KKC by entering into a Stock Purchase Agreement, pursuant to which we sold to KKC an aggregate of 2.9 million shares of our common stock for aggregate gross proceeds of approximately $20.0 million.

As of December 31, 2021, we had cash, cash equivalents and investments totaling $116.7 million.

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INTELLECTUAL PROPERTY

Our commercial success depends in part on our ability to obtain and maintain proprietary protection for our drug candidates, manufacturing and process discoveries, and other know-how, to operate without infringing the proprietary rights of others and to prevent others from infringing our proprietary rights. Our policy is to seek to protect our intellectual property by, among other methods, filing U.S. and foreign patent applications related to our proprietary technology and inventions that are important to the development and operation of our business. We also rely on trade secrets and careful monitoring of our proprietary information to protect aspects of our business that are not amenable to, or that we do not consider appropriate for, patent protection.

The patent positions of biopharmaceutical companies like us are generally uncertain and involve complex legal, scientific and factual questions. In addition, the coverage claimed in a patent application can be significantly reduced before the patent is issued, and its scope can be reinterpreted after issuance. Consequently, we do not know whether any of our product candidates will be protectable or remain protected by enforceable patents. We cannot predict whether the patent applications we are currently pursuing will issue as patents in any particular jurisdiction or whether the claims of our issued patents will provide sufficient proprietary protection from competitors. Any patents that we hold may be challenged, circumvented or invalidated by third parties. If third parties prepare and file patent applications in the United States that also claim technology or therapeutics to which we have rights, we may have to participate in interference proceedings in the U.S. Patent and Trademark Office (the “USPTO”) to determine priority of invention, which would result in substantial costs to us even if the eventual outcome is favorable to us.

The term of individual patents depends upon the legal term of the patents in countries in which they are obtained. In most countries, including the United States, the patent term is generally 20 years from the earliest date of filing a non-provisional patent application in the applicable country. In the U.S., a patent’s term may, in certain cases, be lengthened by patent term adjustment, which compensates a patentee for administrative delays by the USPTO in examining and granting a patent, or may be shortened if a patent is terminally disclaimed over a commonly owned patent or a patent naming a common inventor and having an earlier expiration date.

In addition, in the United States, the Hatch-Waxman Act permits a patent term extension of up to five years beyond the expiration of a U.S. patent as partial compensation for the patent term lost during the FDA regulatory review process occurring while the patent is in force. A patent extension cannot extend the remaining term of a patent beyond a total of 14 years from the date of product approval, and only one patent applicable to each regulatory review period may be extended and only those claims covering the approved drug, a method for using it or a method for manufacturing it may be extended. Similar provisions are available in the European Union and certain other foreign jurisdictions to extend the term of a patent that covers an approved drug.

We may rely, in some circumstances, on trade secrets to protect our technology. Although we take steps to protect our proprietary information and trade secrets, including through contractual means with our employees and consultants, third parties may independently develop substantially equivalent proprietary information and techniques or otherwise gain access to our trade secrets or disclose our technology. Thus, we may not be able to meaningfully protect our trade secrets. It is our policy to require our employees, consultants, outside scientific collaboration partners, sponsored researchers and other advisors to execute confidentiality agreements upon the commencement of employment or consulting relationships with us. These agreements provide that all confidential information concerning the business or financial affairs developed or made known to the individual during the course of the individual’s relationship with us is to be kept confidential and not disclosed to third parties except in specific circumstances. In the case of employees, the agreements provide that all inventions conceived by the individual, and which are related to our current or planned business or research and development or made during the normal working hours, on our premises or using our equipment or proprietary information, are our exclusive property.

Tenapanor Patents

Our tenapanor patent portfolio is wholly owned by us. This portfolio includes five issued U.S. patents, three issued Israeli patents, two issued patents in each of European Patent Organization, Japan, Korea, Hong Kong and Mexico and one issued patent in each of the following territories: Australia, Brazil, India, and China. These issued patents cover the composition and certain methods of using tenapanor and are predicted, without extension or adjustment, to expire in December 2029. The portfolio further includes patents covering the use of tenapanor for the control of serum phosphorus that have been issued in the U.S., Europe, Japan, China, Australia, Gulf Co-op countries, Hong Kong, Israel, Korea, Mexico, New Zealand, Russia and Taiwan and is pending in other countries. These patents are predicted, without extension or adjustment, to expire in April 2034.

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Additional U.S. and international patent applications are pending covering additional methods of treatment with tenapanor, and composition of matter and methods of using compounds that we believe may be follow on compounds to tenapanor.

Other Program Patents

We have patent applications pending in the U.S. and internationally that cover the compositions and methods of using compounds in our RDX013 program.

MANUFACTURING

To date, we have relied upon third-party contract manufacturing organizations (“CMOs”) to manufacture both the active pharmaceutical ingredient and final drug product dosage forms of our potential drug candidates used as clinical trial material. We expect that we will continue to rely upon CMOs for the manufacture of commercial product for IBSRELA, our clinical trial materials and for our commercial product requirements for XPHOZAH, when and if regulatory approval is received. Our license agreements with Knight, and Fosun Pharma require us to supply final drug product dosage forms of tenapanor for their use in the development and commercialization of tenapanor in each of their respective territories. We are further obligated to supply active pharmaceutical ingredient to KKC to support their development and commercialization of tenapanor in Japan. We expect that we will use CMOs to satisfy our supply obligations to our collaboration partners.

GOVERNMENT REGULATION

The FDA and comparable regulatory authorities in state and local jurisdictions and in other countries impose substantial and burdensome requirements upon companies involved in the clinical development, manufacture, marketing and distribution of drugs. These agencies and other federal, state and local entities regulate research and development activities and the testing, manufacture, quality control, safety, effectiveness, labeling, storage, record keeping, approval, advertising and promotion, distribution, post-approval monitoring and reporting, sampling, and export and import of our product candidates.

In the United States, the FDA regulates drug products under the Federal Food, Drug, and Cosmetic Act (the “FFDCA”) and the FDA’s implementing regulations. If we fail to comply with applicable FDA or other requirements at any time during the drug development process, the approval process or after approval, we may become subject to administrative or judicial sanctions. These sanctions could include the FDA’s refusal to approve pending applications, license suspension or revocation, withdrawal of an approval, warning or untitled letters, product recalls, product seizures, total or partial suspension of production or distribution, injunctions, fines, civil penalties or criminal prosecution. Any FDA enforcement action could have a material adverse effect on us. FDA approval is required before any new unapproved drug or dosage form, including a new use of a previously approved drug, can be marketed in the United States.

The process required by the FDA before a drug may be marketed in the United States generally involves:

•completion of extensive preclinical laboratory tests, preclinical animal studies and formulation studies, some performed in accordance with the FDA’s current Good Laboratory Practice (“GLP”) regulations;

•submission to the FDA of an Investigational New Drug (“IND”) application which must become effective before human clinical trials in the United States may begin;

•approval by an independent institutional review board, (“IRB”) or ethics committee at each clinical trial site before each trial may be initiated;

•performance of adequate and well-controlled human clinical trials in accordance with Good Clinical Practice ("GCP") regulations to establish the safety and efficacy of the drug candidate for each proposed indication;

•submission to the FDA of a new drug application (“NDA”);

•satisfactory completion of an FDA inspection of the manufacturing facility or facilities at which the drug is produced to assess compliance with current Good Manufacturing Practice (“cGMP”) regulations;

•satisfactory completion of a potential review by an FDA advisory committee, if applicable; and

•FDA review and approval of the NDA prior to any commercial marketing, sale or commercial shipment of the drug.

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The preclinical and clinical testing and approval process requires substantial time, effort and financial resources, and we cannot be certain that any approvals for our product candidates will be granted on a timely basis, if at all. Nonclinical tests include laboratory evaluation of product chemistry, formulation, stability and toxicity, as well as animal studies to assess the characteristics and potential safety and efficacy of the product. The results of preclinical tests, together with manufacturing information, analytical data and a proposed clinical trial protocol and other information, are submitted as part of an IND to the FDA. Additional preclinical testing may continue even after the IND is submitted. The IND automatically becomes effective 30 days after receipt by the FDA, unless the FDA, within the 30-day period, raises concerns or questions relating to the IND and places the clinical trial on a clinical hold, including concerns that human research subjects will be exposed to unreasonable health risks. In such a case, the IND sponsor and the FDA must resolve any outstanding concerns before the clinical trial can begin. A separate submission to an existing IND must also be made for each successive clinical trial conducted during product development.

Clinical trials involve the administration of the investigational drug to human subjects under the supervision of qualified investigators. Clinical trials are conducted under protocols detailing, among other things, the objectives of the clinical trial, the parameters to be used in monitoring safety and the effectiveness criteria to be used. Each protocol must be submitted to the FDA as part of the IND.

An independent IRB or ethics committee for each medical center proposing to conduct a clinical trial must also review and approve a plan for any clinical trial before it can begin at that center and the IRB must monitor the clinical trial until it is completed. The FDA, the IRB, or the sponsor may suspend or discontinue a clinical trial at any time on various grounds, including a finding that the subjects are being exposed to an unacceptable health risk. Clinical testing also must satisfy extensive GCP requirements, including the requirements for informed consent.

All clinical research performed in the United States in support of an NDA must be submitted in advance by the FDA under the IND regulations and procedures described above. However, a sponsor who wishes to conduct a clinical trial outside the United States may, but need not, obtain FDA authorization to conduct the clinical trial under an IND. If a foreign clinical trial is not conducted under an IND, the sponsor may submit data from the clinical trial to the FDA in support of an NDA so long as the clinical trial is conducted in compliance with GCP and if the FDA is able to validate the data from the study through an onsite inspection, if necessary. GCP includes review and approval by an independent ethics committee, such as an IRB, and obtaining and documenting the freely given informed consent of each subject before study initiation. If the applicant seeks approval of an NDA solely on the basis of foreign data, the FDA will only accept such data if they are applicable to the U.S. population and U.S. medical practice, the studies have been performed by clinical investigators of recognized competence, and the data may be considered valid without the need for an on-site inspection by the FDA, or if the FDA considers such an inspection to be necessary, the FDA is able to validate the data through an on-site inspection or through other appropriate means.

Clinical Trials

The clinical investigation of a new drug is typically conducted in three or four phases, which may overlap or be combined, and generally proceed as follows.

•Phase 1: Clinical trials are initially conducted in a limited population of subjects to test the drug candidate for safety, dose tolerance, absorption, metabolism, distribution and excretion in healthy humans or, on occasion, in patients with severe problems or life-threatening diseases to gain an early indication of its effectiveness.

•Phase 2: Clinical trials are generally conducted in a limited patient population to evaluate dosage tolerance and appropriate dosage, identify possible adverse effects and safety risks, and evaluate preliminarily the efficacy of the drug for specific targeted indications in patients with the disease or condition under study.

•Phase 3: Clinical trials are typically conducted when Phase 2 clinical trials demonstrate that a dose range of the product candidate is effective and has an acceptable safety profile. Phase 3 clinical trials are commonly referred to as “pivotal” studies, which typically denotes a study which presents the data that the FDA or other relevant regulatory agency will use to determine whether or not to approve a drug. Phase 3 clinical trials are generally undertaken with large numbers of patients, such as groups of several hundred to several thousand, to further evaluate dosage, to provide substantial evidence of clinical efficacy and to further test for safety in an expanded and diverse patient population at multiple, geographically-dispersed clinical trial sites.

•Phase 4: In some cases, the FDA may condition approval of an NDA for a product candidate on the sponsor’s agreement to conduct additional clinical trials after NDA approval. In other cases, a sponsor may voluntarily conduct

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additional clinical trials post approval to gain more information about the drug. Such post approval trials are typically referred to as Phase 4 clinical trials.

Concurrent with clinical trials, companies usually complete additional nonclinical studies and must also develop additional information about the chemistry and physical characteristics of the drug and finalize a process for manufacturing the drug in commercial quantities in accordance with GMP requirements. The manufacturing process must be capable of consistently producing quality batches of the drug candidate and, among other things, the manufacturer must develop methods for testing the identity, strength, quality and purity of the final drug product. Additionally, appropriate packaging must be selected and tested, and stability studies must be conducted to demonstrate that the drug candidate does not undergo unacceptable deterioration over its shelf life.

The FDA, the IRB or the clinical trial sponsor may suspend or terminate a clinical trial at any time on various grounds, including a finding that the research subjects are being exposed to an unacceptable health risk.

Additionally, some clinical trials are overseen by an independent group of qualified experts organized by the clinical trial sponsor, known as a data safety monitoring board or committee. This group provides authorization for whether or not a trial may move forward at designated check points based on access to certain data from the study. We may also suspend or terminate a clinical trial based on evolving business objectives and/or competitive climate.

New Drug Applications

The results of preclinical studies and of the clinical trials, together with other detailed information, including extensive manufacturing information and information on the composition of the drug, are submitted to the FDA in the form of an NDA requesting approval to market the drug for one or more specified indications. The FDA reviews an NDA to determine, among other things, whether a drug is safe and effective for its intended use.

Under the Prescription Drug User Fee Act, the FDA has a goal of responding to standard review NDAs for new molecular entities within ten months after the 60-day filing review period, or six months after the 60-day filing review period for priority review NDAs and for non-new molecular entities, within ten months of receipt of standard review NDAs and six month of receipt for priority review NDAs, but this timeframe is often extended by FDA requests for additional information or clarification. The FDA may refer the application to an advisory committee for review, evaluation and recommendation as to whether the application should be approved. The FDA is not bound by the recommendation of an advisory committee, but it generally follows such recommendations.

Before approving an application, the FDA may inspect the facility or the facilities at which the finished drug product, and sometimes the active pharmaceutical ingredient (“API”) is manufactured, and will not approve the drug unless cGMP compliance is satisfactory. The FDA may also inspect the sites at which the clinical trials were conducted to assess their compliance and will not approve the drug unless compliance with GCP requirements is satisfactory.

After the FDA evaluates the NDA and conducts inspections of manufacturing facilities where the drug product and/or its API will be produced, if deemed necessary, it may issue an approval letter or a Complete Response Letter. An approval letter authorizes commercial marketing of the drug with specific prescribing information for specific indications. A Complete Response Letter indicates that the review cycle of the application is complete, and the application is not ready for approval. A Complete Response Letter may require additional clinical data and/or an additional pivotal Phase 3 clinical trial(s), and/or other significant, expensive and time-consuming requirements related to clinical trials, preclinical studies or manufacturing. Even if such additional information is submitted, the FDA may ultimately decide that the NDA does not satisfy the criteria for approval. The FDA could also approve the NDA with a Risk Evaluation and Mitigation Strategy (“REMS”) if it is determined that a REMS is necessary to ensure that the drug’s benefits outweigh its risks and a REMS to mitigate risks, which could include medication guides, physician communication plans, or elements to assure safe use, such as restricted distribution methods, patient registries and other risk minimization tools. The FDA also may condition approval on, among other things, changes to proposed labeling, development of adequate controls and specifications, or a commitment to conduct one or more post-market studies or clinical trials. Such post-market testing may include Phase 4 clinical trials and surveillance to further assess and monitor the product’s safety and effectiveness after commercialization. The FDA has the authority to prevent or limit further marketing of a drug based on the results of these post-marketing programs. Once the FDA approves an NDA, or supplement thereto, the FDA may withdraw the approval if ongoing regulatory requirements are not met or if safety problems are identified after the drug reaches the market.

Drugs may be marketed only for the FDA approved indications and in accordance with the provisions of the approved labeling. Further, if there are any modifications to the drug, including changes in indications, labeling, or manufacturing

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processes or facilities, the applicant may be required to submit and obtain FDA approval of a new NDA or NDA supplement, which may require the applicant to develop additional data or conduct additional preclinical studies and clinical trials.

The testing and approval processes require substantial time, effort and financial resources, and each may take several years to complete. The FDA may not grant approval on a timely basis, or at all. Even if we believe a clinical trial has demonstrated safety and efficacy of one of our drug candidates for the proposed indication, the results may not be satisfactory to the FDA. Nonclinical and clinical data may be interpreted by the FDA in different ways, which could delay, limit or prevent regulatory approval. We may encounter difficulties or unanticipated costs in our efforts to secure necessary governmental approvals which could delay or preclude us from marketing drugs. The FDA may limit the indications for use or place other conditions on any approvals that could restrict the commercial application of the drugs. After approval, certain changes to the approved drug, such as adding new indications, manufacturing changes, or additional labeling claims are subject to further FDA review and approval. Depending on the nature of the change proposed, an NDA supplement must be filed and approved before the change may be implemented.

Other Regulatory Requirements

Any drugs manufactured or distributed by us or our collaboration partners pursuant to FDA approvals would be subject to continuing regulation by the FDA, including recordkeeping requirements and reporting of adverse experiences associated with the drug. Drug manufacturers and their subcontractors are required to register their establishments with the FDA and certain state agencies and are subject to periodic announced and unannounced inspections by the FDA and certain state agencies for compliance with ongoing regulatory requirements, including cGMP, which impose certain procedural and documentation requirements upon us and our third-party manufacturers. Failure to comply with the statutory and regulatory requirements can subject a manufacturer to possible legal or regulatory action, such as warning or untitled letters, suspension of manufacturing, seizure of product, injunctive action or possible civil penalties. We cannot be certain that we or our present or future third-party manufacturers or suppliers will be able to comply with the cGMP regulations and other ongoing FDA regulatory requirements. If we or our present or future third-party manufacturers or suppliers are not able to comply with these requirements, the FDA may, among other things, halt our clinical trials, require us to recall a drug from distribution or withdraw approval of the NDA for that drug.

The FDA closely regulates the post-approval marketing and promotion of drugs, including standards and regulations for direct-to-consumer advertising, off-label promotion, industry-sponsored scientific and educational activities and promotional activities involving the Internet. A company can make only those claims relating to safety and efficacy that are in the final label or consistent with the final label. Failure to comply with these requirements can result in, among other things, adverse publicity, warning or untitled letters, corrective advertising and potential civil and criminal penalties. Physicians may prescribe legally available drugs for uses that are not described in the product’s labeling and that differ from those tested by us and approved by the FDA. Such off-label uses are common across medical specialties. Physicians may believe that such off-label uses are the best treatment for many patients in varied circumstances. The FDA does not regulate the behavior of physicians in their choice of treatments. The FDA does, however, impose stringent restrictions on manufacturers’ communications regarding off-label use.

Hatch-Waxman Act

Under the Price Competition and Patent Term Restoration Act, or Hatch-Waxman Act, Section 505 of the FFDCA describes three types of marketing applications that may be submitted to the FDA to request marketing authorization for a new drug. A Section 505(b)(1) NDA is an application that contains full reports of investigations of safety and efficacy. A Section 505(b)(2) NDA is an application that contains full reports of investigations of safety and efficacy but where at least some of the information required for approval comes from investigations that were not conducted by or for the applicant and for which the applicant has not obtained a right of reference or use from the person by or for whom the investigations were conducted. This regulatory pathway enables the applicant to rely, in part, on the FDA’s prior findings of safety and efficacy for an existing product, or published literature, in support of its application. Section 505(j) establishes an abbreviated approval process for a generic version of approved drug products through the submission of an Abbreviated New Drug Application (“ANDA”). An ANDA provides for marketing of a generic drug product that has the same active ingredients, dosage form, strength, route of administration, labeling, performance characteristics and intended use, among other things, to a previously approved product. ANDAs are termed “abbreviated” because they are generally not required to include nonclinical (animal) and clinical (human) data to establish safety and efficacy. Instead, generic applicants must scientifically demonstrate that their product is bioequivalent to, or performs in the same manner as, the innovator drug through in vitro, in vivo, or other testing. The generic version must deliver the same amount of active ingredients into a subject’s bloodstream in the same amount of time as the innovator drug and can often be substituted by pharmacists under prescriptions written for the reference listed drug. In seeking approval for a drug through an NDA, applicants are required to list with the FDA each patent with claims that cover the

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applicant’s drug or a method of using the drug. Upon approval of a drug, each of the patents listed in the application for the drug is then published in the FDA’s Approved Drug Products with Therapeutic Equivalence Evaluations, commonly known as the Orange Book. Drugs listed in the Orange Book can, in turn, be cited by potential competitors in support of approval of an ANDA or 505(b)(2) NDA.

Upon submission of an ANDA or a 505(b)(2) NDA, an applicant must certify to the FDA that (1) no patent information on the drug product that is the subject of the application has been submitted to the FDA; (2) such patent has expired; (3) the date on which such patent expires; or (4) such patent is invalid or will not be infringed upon by the manufacture, use or sale of the drug product for which the application is submitted. Generally, the ANDA or 505(b)(2) NDA cannot be approved until all listed patents have expired, except where the ANDA or 505(b)(2) NDA applicant challenges a listed patent through the last type of certification, also known as a Paragraph IV certification. If the applicant does not challenge the listed patents or indicates that it is not seeking approval of a patented method of use, the ANDA or 505(b)(2) NDA application will not be approved until all of the listed patents claiming the referenced product have expired.

If the ANDA or 505(b)(2) NDA applicant has provided a Paragraph IV certification to the FDA, the applicant must send notice of the Paragraph IV certification to the NDA holder and patent owners once the application has been accepted for filing by the FDA. The NDA and patent holders may then initiate a patent infringement lawsuit in response to the notice of the Paragraph IV certification. If the Paragraph IV certification is challenged by an NDA holder or the patent owner(s), the FDA may not approve that application until the earlier of 30 months from the receipt of the notice of the Paragraph IV certification, the expiration of the patent, when the infringement case concerning each such patent was favorably decided in the applicant’s favor or settled, or such shorter or longer period as may be ordered by a court. This prohibition is generally referred to as the 30-month stay. In instances where an ANDA or 505(b)(2) NDA applicant files a Paragraph IV certification, the NDA holder or patent owner(s) regularly take action to trigger the 30-month stay, recognizing that the related patent litigation may take many months or years to resolve. Thus, approval of an ANDA or 505(b)(2) NDA could be delayed for a significant period of time depending on the patent certification the applicant makes and the reference drug sponsor’s decision to initiate patent litigation.

The Hatch-Waxman Act establishes periods of regulatory exclusivity for certain approved drug products, during which the FDA cannot approve (or in some cases accept) an ANDA or 505(b)(2) application that relies on the branded reference drug. For example, the holder of an NDA, including a 505(b)(2) NDA, may obtain five years of exclusivity upon approval of a new drug containing a new chemical entity (“NCE”) that has not been previously approved by the FDA. A drug is a new chemical entity if the FDA has not previously approved any other new drug containing the same active moiety, which is the molecule or ion responsible for the therapeutic activity of the drug substance. During the exclusivity period, the FDA may not accept for review an ANDA or a 505(b)(2) NDA submitted by another company that contains the previously approved active moiety. However, an ANDA or 505(b)(2) NDA may be submitted after four years if it contains a Paragraph IV certification of patent invalidity or non-infringement.

The Hatch-Waxman Act also provides three years of marketing exclusivity to the holder of an NDA (including a 505(b)(2) NDA) for a particular condition of approval, or change to a marketed product, such as a new formulation for a previously approved product, if one or more new clinical studies (other than bioavailability or bioequivalence studies) was essential to the approval of the application and was conducted/sponsored by the applicant. This three-year exclusivity period protects against FDA approval of ANDAs and 505(b)(2) NDAs for the specific condition of the new drug’s approval. As a general matter, the three-year exclusivity does not prohibit the FDA from approving ANDAs or 505(b)(2) NDAs for generic versions of the original, unmodified drug product. Five-year and three-year exclusivity will not delay the submission or approval of a full NDA; however, an applicant submitting a full NDA would be required to conduct or obtain a right of reference to all of the preclinical studies and adequate and well-controlled clinical trials necessary to demonstrate safety and efficacy.

Fraud and Abuse Laws

In the U.S. the research, manufacturing, distribution, sale and promotion of drug products and medical devices are potentially subject to regulation by various federal, state and local authorities in addition to the FDA, including the Centers for Medicare & Medicaid Services (“CMS”) other divisions of the U.S. Department of Health and Human Services (e.g., the Office of Inspector General), the U.S. Department of Justice, state Attorneys General, and other state and local government agencies. These laws include but are not limited to, the Anti-Kickback Statute, the federal False Claims Act, the federal Physician Payments Sunshine Act, and other state and federal laws and regulations.

The Anti-Kickback Statute makes it illegal for any person, including a prescription drug manufacturer (or a party acting on its behalf) to knowingly and willfully solicit, receive, offer, or pay any remuneration that is intended to induce the referral of business, including the purchase, order, or prescription of a particular drug, for which payment may be made under a federal

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healthcare program, such as Medicare or Medicaid. Violations of this law are punishable by up to five years in prison, criminal fines, administrative civil money penalties, and exclusion from participation in federal healthcare programs. In addition, a person or entity does not need to have actual knowledge of the statute or specific intent to violate it in order to have committed a violation.

The federal False Claims Act prohibits anyone from knowingly presenting, or causing to be presented, for payment to federal programs (including Medicare and Medicaid) claims for items or services, including drugs, that are false or fraudulent, claims for items or services not provided as claimed, or claims for medically unnecessary items or services. Although we would not submit claims directly to payors, manufacturers can be held liable under these laws if they are deemed to “cause” the submission of false or fraudulent claims by, for example, providing inaccurate billing or coding information to customers or promoting a product off-label. In addition, our future activities relating to the reporting of wholesaler or estimated retail prices for our products, the reporting of prices used to calculate Medicaid rebate information and other information affecting federal, state, and third-party reimbursement for our products, and the sale and marketing of our products, are subject to scrutiny under this law. Moreover, the government may assert that a claim including items or services resulting from a violation of the federal Anti-Kickback Statute constitutes a false or fraudulent claim for purposes of the False Claims Act. Penalties for a False Claims Act violation include three times the actual damages sustained by the government, plus mandatory civil penalties for each separate false claim, the potential for exclusion from participation in federal healthcare programs. As well, although the federal False Claims Act is a civil statute, conduct that results in a False Claims Act violation may also implicate various federal criminal statutes. If the government were to allege that we were, or convict us of, violating these false claims laws, we could be subject to a substantial fine and may suffer a decline in our stock price. In addition, private individuals have the ability to bring actions under the federal False Claims Act.

In addition to the laws described above, the Physician Payments Sunshine Act requires certain drug manufacturers to report payments and other transfer of value made to physicians (defined to include doctors, dentists, optometrists, podiatrists and chiropractors) certain non-physician practitioners (physician assistants, nurse practitioners, clinical nurse specialists, certified nurse anesthetists, anesthesiologist assistants and certified nurse midwives) and teaching hospitals, as well as ownership and investment interests held by physicians and their immediate family members. Failure to submit required information may result in significant civil monetary penalties, and additional penalties for knowing failures, for all payments, transfers of value or ownership or investment interests that are not timely, accurately and completely reported in an annual submission. Manufacturers must submit reports by the 90th day of each subsequent calendar year.

Many states have also adopted laws similar to the federal laws discussed above. Some of these state prohibitions apply to the referral of patients for healthcare services reimbursed by any insurer, not just federal healthcare programs such as Medicare and Medicaid. There has also been a recent trend of increased regulation of payments made to physicians and other healthcare providers. Certain states mandate implementation of compliance programs, impose restrictions on drug manufacturers’ marketing practices and/or require the tracking and reporting of pricing and marketing information as well as gifts, compensation and other remuneration to physicians. Many of these laws contain ambiguities as to what is required to comply with such laws, which may affect our sales, marketing, and other promotional activities by imposing administrative and compliance burdens on us. In addition, given the lack of clarity with respect to these laws and their implementation, our reporting actions could be subject to the penalty provisions of the pertinent state and perhaps federal, authorities.

Violations of any of such laws or any other governmental regulations that apply may result in penalties, including, without limitation, administrative, civil and criminal penalties, damages, fines, disgorgement, the curtailment or restructuring of operations, reporting obligations and integrity oversight, exclusion from participation in federal and state healthcare programs and imprisonment.

Third-Party Coverage and Reimbursement

Sales of pharmaceutical products depend in significant part on the availability of coverage and adequate reimbursement by third-party payors, such as state and federal governments, including Medicare and Medicaid, and commercial managed care providers. In the United States, no uniform policy of coverage and reimbursement for drug products exists among third-party payors. Accordingly, decisions regarding the extent of coverage and amount of reimbursement to be provided for our product candidates, if approved, will be made on a payor by payor basis. As a result, the coverage determination process is often a time-consuming and costly process that will require us to provide scientific and clinical support for the use of our product candidates to each payor separately, with no assurance that coverage and adequate reimbursement will be obtained. Third-party payors may limit coverage to specific drug products on an approved list, or formulary, which might not include all of the FDA-approved drugs for a particular indication. A decision by a third-party payor not to cover our product candidates could reduce physician utilization of our products once approved and have a material adverse effect on our future sales, results of operations and financial condition. Moreover, a payor’s decision to provide coverage for a drug product does not imply that an adequate

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reimbursement rate will be approved. Adequate third-party reimbursement may not be available to enable us to maintain price levels sufficient to realize an appropriate return on our investment in product development.

There is increased uncertainty related to insurance coverage and reimbursement for certain drugs, like XPHOZAH, which, if approved, will be marketed for the control of serum phosphorus in adult patients with CKD on dialysis. In January 2011, CMS implemented a new prospective payment system for dialysis treatment. Under the ESRD prospective payment system, CMS generally makes a single bundled payment to the dialysis facility for each dialysis treatment that covers all items and services routinely required for dialysis treatments furnished to Medicare beneficiaries in Medicare-certified ESRD facilities or at their home, including the cost of certain routine drugs. The inclusion of oral medications without injectable or intravenous equivalents in the bundled payment was initially delayed until January 1, 2014 and through several subsequent legislative actions was delayed until January 1, 2025. As a result, absent further legislation or regulation on this matter, beginning in 2025, oral ESRD-related drugs without injectable or intravenous equivalents may be included in the ESRD bundle and separate Medicare payment for these drugs will no longer be available, as is the case today under Medicare Part D. While it is too early to project the full impact that bundling may have on XPHOZAH and our business should XPHOZAH be brought into the bundle in 2025, or at any time, we may be unable to sell XPHOZAH, if approved, to dialysis providers on a profitable basis if third-party payors reduce their current levels of payment, or if our costs of production are higher than levels necessary for an appropriate gross margin after payment of all discounts, rebates and chargebacks.

Healthcare Reform

In March 2010, Congress passed the Patient Protection and Affordable Care Act, a healthcare reform measure (the “ACA”). The ACA was signed into law and substantially changed the way healthcare is financed by both governmental and private insurers, and significantly impacted the pharmaceutical industry.

The ACA contained a number of provisions, including those governing enrollment in federal healthcare programs, reimbursement changes and fraud and abuse measures, which have impacted existing government healthcare programs and have resulted in the development of new programs, including Medicare payment for performance initiatives and improvements to the physician quality reporting system and feedback program.

Additionally, the ACA:

•increased the minimum level of Medicaid rebates payable by manufacturers of brand-name drugs from 15.1% to 23.1% of the average manufacturer price;

•required collection of rebates for drugs paid by Medicaid managed care organizations;

•expanded eligibility criteria for Medicaid programs by, among other things, allowing states to offer Medicaid coverage to additional individuals and by adding new mandatory eligibility categories for certain individuals with income at or below 133% of the federal poverty level, thereby potentially increasing a manufacturer’s Medicaid rebate liability;

•expanded access to commercial health insurance coverage through new state-based health insurance marketplaces, or exchanges;

•required manufacturers to participate in a coverage gap discount program, under which they must now agree to offer 70% point-of-sale discounts off negotiated prices of applicable brand drugs to eligible beneficiaries during their coverage gap period, as a condition for the manufacturer’s outpatient drugs to be covered under Medicare Part D; and

•imposed a non-deductible annual fee on pharmaceutical manufacturers or importers who sell “branded prescription drugs” to specified federal government programs.

Since its enactment, there have been judicial, executive and Congressional challenges to certain aspects of the ACA. On June 17, 2021, the U.S. Supreme Court dismissed a challenge on procedural grounds that argued the ACA is unconstitutional in its entirety because the “individual mandate” was repealed by Congress. Thus, the ACA will remain in effect in its current form. Further, prior to the U.S. Supreme Court ruling, President Biden issued an executive order that initiated a special enrollment period for purposes of obtaining health insurance coverage through the ACA marketplace from February 15, 2021 through August 15, 2021. The executive order instructed certain governmental agencies to review and reconsider their existing policies and rules that limit access to healthcare, including among others, reexamining Medicaid demonstration projects and waiver programs that include work requirements, and policies that create unnecessary barriers to obtaining access to health insurance coverage through Medicaid or the ACA.

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In addition, other legislative changes have been proposed and adopted in the United States since the ACA was enacted. For example, in August 2011, the Budget Control Act of 2011, among other things, included aggregate reductions to Medicare payments to providers of 2% per fiscal year, which went into effect on April 1, 2013, and, due to subsequent legislative amendments, will remain in effect through 2030, with the exception of a temporary suspension from May 1, 2020 through March 31, 2022 and a 1% reduction from April 1, 2022 through June 30, 2022, unless additional Congressional action is taken. In January 2013, the American Taxpayer Relief Act, among other things, further reduced Medicare payments to several providers, including hospitals, imaging centers and cancer treatment centers, and increased the statute of limitations period for the government to recover overpayments to providers from three to five years. More recently, on March 11, 2021, President Biden signed the American Rescue Plan Act of 2021 into law, which eliminates the statutory Medicaid drug rebate cap, currently set at 100% of a drug’s average manufacturer price, beginning January 1, 2024.

Recently, there has also been heightened governmental scrutiny over the manner in which drug manufacturers set prices for their marketed products, which has resulted in several Congressional inquiries and proposed bills designed to, among other things, bring more transparency to product pricing, review the relationship between pricing and manufacturer patient programs, and reform government program reimbursement methodologies for drug products. By way of example, the Build Back Better Act, if enacted, would introduce substantial drug pricing reforms, including the establishment of a drug price negotiation program within the U.S. Department of Health and Human Services that would require manufacturers to charge a negotiated “maximum fair price” for certain selected drugs or pay an excise tax for noncompliance, and the establishment of rebate payment requirements on manufacturers of certain drugs payable under Medicare Parts B and D. If the Build Back Better Act is not enacted, similar or other drug pricing proposals could appear in future legislation. Additionally, individual states have also become increasingly active in passing legislation and implementing regulations designed to control pharmaceutical product pricing, including price or patient reimbursement constraints, discounts, restrictions on certain product access, and to encourage importation from other countries and bulk purchasing. These new laws and the regulations and policies implementing them, as well as other healthcare reform measures that may be adopted in the future, may have a material adverse effect on our industry generally and on our ability to successfully develop and commercialize our products.

Government Price Reporting

Medicaid is a joint federal and state program for low-income and disabled beneficiaries. Medicare is a federal program covering individuals age 65 and over as well as those with certain disabilities. As a condition of having federal funds being made available for our covered drugs under Medicaid, we intend to enroll in the Medicaid Drug Rebate Program (“MDRP”), which would require us to pay a rebate to state Medicaid programs for each unit of our covered drugs dispensed to a Medicaid beneficiary and paid for by a state Medicaid program. Medicaid drug rebates are based on pricing data that we must report on a monthly and quarterly basis to the U.S. Centers for Medicare & Medicaid Services (“CMS”), the federal agency that administers the MDRP and Medicare programs. For the MDRP, these data include the average manufacturer price (“AMP”) and the best price (“BP”) for each drug. If we become aware that our MDRP price reporting submission for a prior period was incorrect or has changed as a result of recalculation of the pricing data, we must resubmit the corrected data for up to three years after those data originally were due. Manufacturers who fail to provide information timely or are found to have knowingly submitted false information to the government may be subject to civil monetary penalties and other sanctions, including termination from the MDRP.

Federal law requires that a manufacturer that participates in the MDRP also participate in the Public Health Service’s 340B drug pricing program (the “340B program”) in order for federal funds to be available for the manufacturer’s drugs under Medicaid and Medicare Part B. We intend to participate in the 340B program, which is administered by the Health Resources and Services Administration (“HRSA”), and requires us to charge statutorily defined covered entities no more than the 340B “ceiling price” for the our covered outpatient drugs used in an outpatient setting. These 340B covered entities include a variety of community health clinics and other entities that receive health services grants from the Public Health Service, as well as hospitals that serve a disproportionate share of low-income patients. The 340B ceiling price calculated using a statutory formula, which is based on the AMP and rebate amount for the covered outpatient drug as calculated under the MDRP. In general, products subject to Medicaid price reporting and rebate liability are also subject to the 340B ceiling price calculation and discount requirement. We must report 340B ceiling prices to HRSA on a quarterly basis, and HRSA publishes them to 340B covered entities. HRSA has finalized regulations regarding the calculation of the 340B ceiling price and the imposition of civil monetary penalties on manufacturers that knowingly and intentionally overcharge covered entities for 340B-eligible drugs. HRSA has also finalized an administrative dispute resolution process through which 340B covered entities may pursue claims against participating manufacturers for overcharges, and through which manufacturers may pursue claims against 340B covered entities for engaging in unlawful diversion or duplicate discounting of 340B drugs. In addition, legislation may be introduced that, if passed, would further expand the 340B program, such as adding further covered entities or requiring participating manufacturers to agree to provide 340B discounted pricing on drugs used in an inpatient setting.

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In order to be eligible to have drug products paid for with federal funds under Medicaid and purchased by certain federal agencies and grantees, manufacturers must also participate in the U.S. Department of Veterans Affairs (“VA”) Federal Supply Schedule (“FSS”) pricing program. Under the VA/FSS program, manufacturers must report the Non-Federal Average Manufacturer Price (“Non-FAMP”) for their covered drugs to the VA and charge certain federal agencies no more than the Federal Ceiling Price, which is calculated based on Non-FAMP using a statutory formula. These four agencies are the VA, the U.S. Department of Defense, the U.S. Coast Guard, and the U.S. Public Health Service (including the Indian Health Service). Manufacturers must also pay rebates on products purchased by military personnel and dependents through the TRICARE retail pharmacy program. Manufacturers who fail to provide timely information or are found to have knowingly submitted false information may be subject to civil monetary penalties.

Individual states continue to consider and have enacted legislation to limit the growth of healthcare costs, including the cost of prescription drugs and combination products. A number of states have either implemented or are considering implementation of drug price transparency legislation. Requirements under such laws include advance notice of planned price increases, reporting price increase amounts and factors considered in taking such increases, wholesale acquisition cost information disclosure to prescribers, purchasers, and state agencies, and new product notice and reporting. Such legislation could limit the price or payment for certain drugs, and a number of states are authorized to impose civil monetary penalties or pursue other enforcement mechanisms against manufacturers who fail to comply with drug price transparency requirements, including the untimely, inaccurate, or incomplete reporting of drug pricing information.

Data Privacy and Security Laws

Numerous state, federal and foreign laws, including consumer protection laws and regulations, govern the collection, dissemination, use, access to, confidentiality and security of personal information, including health-related information. In the United States, numerous federal and state laws and regulations, including data breach notification laws, health information privacy and security laws, including the Health Insurance Portability and Accountability Act of 1996, as amended, and regulations promulgated thereunder (collectively “HIPAA”), and federal and state consumer protection laws and regulations (e.g., Section 5 of the Federal Trade Commission Act), that govern the collection, use, disclosure, and protection of health-related and other personal information could apply to our operations or the operations of our partners. In addition, certain state laws, such as the California Consumer Privacy Act (“CCPA”) and the California Privacy Rights Act (“CPRA”) govern the privacy and security of personal data, including health-related data in certain circumstances, some of which are more stringent than HIPAA and many of which differ from each other in significant ways and may not have the same effect, thus complicating compliance efforts. Further, certain foreign laws govern the privacy and security of personal data, including health-related data. Failure to comply with these laws, where applicable, can result in the imposition of significant civil and/or criminal penalties and private litigation. Privacy and security laws, regulations, and other obligations are constantly evolving, may conflict with each other to complicate compliance efforts, and can result in investigations, proceedings, or actions that lead to significant civil and/or criminal penalties and restrictions on data processing.

Other Regulations

We are also subject to numerous federal, state and local laws relating to such matters as safe working conditions, manufacturing practices, environmental protection, fire hazard control, and disposal of hazardous or potentially hazardous substances. We may incur significant costs to comply with such laws and regulations now or in the future.

Impact of COVID-19

The global COVID-19 pandemic has impacted the operational decisions of companies worldwide. It also has created and may continue to create significant uncertainty in the global economy. We have undertaken measures to protect our employees, partners, collaborators, and vendors, some of which impact our normal operations. To date, we have been able to continue our operations with our workforce, most of whom are working remotely, and our pre-existing infrastructure that supports secure access to our internal systems. If, however, the COVID-19 pandemic has a substantial impact on the productivity of our employees, our ability to successfully prepare for and execute the commercial launch of IBSRELA, including our ability to hire and successfully integrate into the company the new personnel required to prepare for such launch, or our ability to pursue our appeal of the ADL issued by OHCEN following the issuance of a CRL for our NDA for tenapanor for the control of serum phosphorus in adult patients with CKD on dialysis, the results of our operations and overall financial performance may be adversely impacted. The extent of the impact from the COVID-19 pandemic on our business will depend largely on future developments that are highly uncertain and cannot be predicted. For a discussion of risks of COVID-19 relating to our business, see “Item 1A. - Risk Factors- Risks Related to Our Business- The ongoing COVID-19 pandemic, or any other outbreak of epidemic diseases, or the perception of their effects, could have a material adverse effect on our business, financial condition,

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results of operations or cash flows.” As of the date of issuance of this financial report, we are not aware of any specific event or circumstance that would require updates to our estimates and judgments or revisions to the carrying value of our assets or liabilities. These estimates may change as new events occur and additional information is obtained.

Human Capital

The future success of our company depends on our ability to attract, retain, and further develop top talent. We plan to launch IBSRELA in April 2022 and, as a result, we are building an experienced commercial team and expanding our internal resources to support a commercial organization. During this ongoing transition and expansion of our workforce, we remain steadfastly committed to our core values, including our goal to develop and maintain an inclusive, diverse, and safe workplace with opportunities for our employees to grow and develop in their careers, supported by strong compensation and benefits.

At December 31, 2021, we had approximately 86 full-time employees, 55 of whom were engaged directly in development and manufacturing, and 31 in marketing, sales and administrative activities. During 2021 our employee base decreased by approximately 43, or 33%, primarily as a result of our restructurings in August 2021 and October 2021.

Inclusion and Diversity

Our culture is supported by an unwavering commitment to inclusion and diversity. As of December 31, 2021, approximately 63% of our workforce was female; 43% of our executive leadership team was female and 56% of our employees in managerial roles were female. As of December 31, 2021, minorities represented approximately 39% of our workforce, of which 41% of our employees in managerial roles were minorities. We strive to foster a culture where mutual respect, inclusive behavior, and dignity are core to our individual expectations.

We believe that our success will be significantly impacted by our ability to create and maintain a safe inclusive environment where everyone is empowered to do their best work—regardless of race, color, national origin, religion, sex, sexual orientation, gender identity and expression, age, or disability. We are united by our desire to serve our patients, and we are proud financial sponsors of the California Life Sciences Association Racial and Social Equity Initiative, a first step in a unified effort for the life sciences industry in California to do more for the under-served and under-represented, focusing on the most critical need to address the inequality for Black, Hispanic, Native American and Pacific Islander populations in California.

Core Values

Fostering and maintaining a strong, healthy culture is a key strategic focus. Our core values reflect who we are and the way our employees interact with one another, our partners and our stockholders. We are dedicated to our core values, recognizing that this dedication will foster an environment where we will be able to realize our vision of advancing patient care. We are Passionate, aware that with integrity and determination, we make a difference for patients. We are Fearless, aware that by challenging convention, we truly innovate. We are Dedicated, aware that working tirelessly together, we are greater than the sum of our parts. We are Inclusive, aware that with respect, grace and humor, we are family. We encourage our employees to live out our core values and to discuss our core values with potential candidates looking to join our team. We believe that this is an important step in helping our culture stay strong and unique.

Health, Safety, and Wellness

The health, safety, and wellness of our employees is a priority in which we have always invested, and will continue to do so. These investments and the prioritization of employee health, safety, and wellness took on particular significance in light of COVID-19. In response to the COVID-19 pandemic, we implemented significant changes that we determined were in the best interest of our employees, as well as the communities in which we operate, in compliance with government regulations. This included having the vast majority of our employees work from home. We have reopened our facilities and are currently inviting our employees to return to our facilities in the manner in which they are comfortable. We will continue to monitor infection rates and severity of disease in those communities in which are facilities are located and will continue to adopt and align our policies to focus on the health, safety and wellness of our employees, and the needs of our business.

Compensation and Benefits

We recognize that we operate within an industry where there is significant competition for top talent, and we endeavor to provide not only a strong healthy culture, but also important compensation and benefits programs to help meet the needs of our employees. In addition to base compensation, these programs, include annual bonuses, stock awards, an Employee Stock Purchase Plan, 401(k), healthcare and insurance benefits, health savings (funded by the Company) and flexible spending

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accounts, family leave, family care resources, and flexible work schedules, among many others. As a response to the COVID-19 pandemic, we implemented payments to assist employees in paying for expenses incurred in working from home.

Ensuring fair and equitable pay is integral to our commitment to our employees. Our executive team and Board of Directors strongly support this commitment. We conduct pay equity reviews annually to help us understand whether our compensation structure is appropriate and to identify what improvements can be made.

Corporate Information

We were incorporated in Delaware on October 17, 2007, under the name Nteryx and changed our name to Ardelyx, Inc. in June 2008. We operate in one business segment, which is the development and planned commercialization of biopharmaceutical products. Our principal office is located at 400 Fifth Avenue, Suite 210, Waltham, Massachusetts 02415. Our telephone number is (510) 745-1700 and our website address is www.ardelyx.com.

We file electronically with the Securities and Exchange Commission (“SEC”) our annual reports on Form 10-K, quarterly reports on Form 10-Q and current reports on Form 8-K pursuant to Section 13(a) or 15(d) of the Securities Exchange Act of 1934, as amended. We make available on our website at www.ardelyx.com, free of charge, copies of these reports, as soon as reasonably practicable after we electronically file such material with, or furnish it to, the SEC. The SEC maintains a website that contains reports, proxy and information statements, and other information regarding issuers that file electronically with the SEC. The address of that website is www.sec.gov.

ITEM 1A. RISK FACTORS

Our business involves significant risks, some of which are described below. You should carefully consider these risks, as well as other information in this Annual Report on Form 10-K, including our financial statements and the notes thereto and “Management’s Discussion and Analysis of Financial Condition and Results of Operations.” The occurrence of any of the events or developments described below could harm our business, financial condition, results of operations, cash flows, the trading price of our common stock and our growth prospects. Many of the following risks and uncertainties are, and will be, exacerbated by the COVID-19 pandemic and any worsening of the global business and economic environment as a result. Additional risks and uncertainties not presently known to us or that we currently deem immaterial may also impair our business operations.

Risks Related to our Financial Condition and Capital Requirements

We have a limited operating history, have incurred significant losses since our inception and we will incur losses in the future, which makes it difficult to assess our future viability; although our financial statements have been prepared on a going concern basis, our current level of cash and investments alone is not sufficient to meet our operating plans for the next twelve months, raising substantial doubt regarding our ability to continue as a going concern.

We are a clinical-stage biopharmaceutical company with a limited operating history. Biopharmaceutical product development is a highly speculative undertaking and involves a substantial degree of risk. To date, we have focused substantially all of our efforts on our research and development activities, including developing tenapanor and developing our proprietary drug discovery and design platform. To date, we have not commercialized any products or generated any revenue from the sale of products.

We are not profitable and have incurred losses in each year since our inception in October 2007, and we do not know whether or when we will become profitable. We continue to incur significant research, development and other expenses related to our ongoing operations. As of December 31, 2021, we had an accumulated deficit of $712.9 million.

We expect to continue to incur substantial operating losses for the foreseeable future as we prepare for commercialization of IBSRELA®(tenapanor) for the treatment of irritable bowel syndrome with constipation (“IBS-C”) in April of this year, seek to gain approval for XPHOZAH® (tenapanor) for the control of serum phosphorus in adult patients with chronic kidney disease (“CKD”) on dialysis (the “Hyperphosphatemia Indication”); prepare for the potential commercialization of XPHOZAH, if approved; incur manufacturing and development cost for, tenapanor; and incur development costs for RDX013.

Ernst & Young LLP, our independent registered public accounting firm for the fiscal year ended December 31, 2021, has included an explanatory paragraph in their opinion that accompanies our audited financial statements as of the year ended December 31, 2021, indicating our current liquidity position raises substantial doubt about our ability to continue as a going

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concern. We plan to address our operating cash flow requirements with our current cash and investments, cash generated from the product launch of IBSRELA, our potential receipt of anticipated milestone payments from our collaboration partners, our ability to access the capital markets, as well as through the implementation of cash preservation activities to reduce or defer discretionary spending.

There are no assurances that our efforts to meet our operating cash flow requirements will be successful. If our current cash and investments as well as our plans to meet our operating cash flow requirements are not sufficient to fund necessary expenditures and meet our obligations for at least the next twelve months, our liquidity, financial condition and business prospects will be materially affected.

Our prior losses, combined with expected future losses, have had and will continue to have an adverse effect on our stockholders’ equity and working capital. Further, the net losses we incur may fluctuate significantly from quarter-to-quarter and year-to-year, such that a period-to-period comparison of our results of operations may not be a good indication of our future performance.

We have substantial net operating loss and tax credit carryforwards for Federal and California income tax purposes. Such net operating losses and tax credits carryforwards may be reduced as a result of certain intercompany restructuring transactions. In addition, the future utilization of such net operating loss and tax credit carryforwards and credits will be subject to limitations, pursuant to Internal Revenue Code Sections 382 and 383, as a result of ownership changes that have occurred previously and additional limitations may be applicable as a result of ownership changes that could occur in the future.

We will require substantial additional financing to achieve our goals, including our goals of commercializing IBSRELA beginning in April 2022 and pursuing a formal dispute resolution ("FDR") process in response to the Complete Response Letter (“CRL”) received from the U.S. Food and Drug Administration (“FDA”) relating to our New Drug Application (“NDA”) for tenapanor for the Hyperphosphatemia Indication and the inability to access necessary capital when needed on acceptable terms, or at all, could force us to delay, limit, reduce or terminate our efforts to commercialize IBSRELA or to seek and obtain approval for tenapanor for the Hyperphosphatemia Indication.

Since our inception, most of our resources have been dedicated to our research and development activities, including developing tenapanor and developing our proprietary drug discovery and design platform. Following the receipt of the CRL, we implemented two restructuring plans in order to reduce operating costs and to better align our workforce with the needs of our business. Notwithstanding the restructurings, we believe that we will continue to expend substantial resources for the foreseeable future, including, costs associated with our efforts to commercialize IBSRELA commencing in April 2022, cost associated with our efforts to pursue approval for our NDA for tenapanor for the Hyperphosphatemia Indication through the FDR process; conducting pediatric clinical trials for IBSRELA and XPHOZAH, if approved, development of RDX013; and manufacturing for IBSRELA and RDX013. Our future funding requirements will depend on many factors, including, but not limited to:

•the extent to which we are able to generate product revenue from sales of IBSRELA;

•whether we are successful in our efforts under the FDR process to secure approval for our NDA for tenapanor for the Hyperphosphatemia Indication, or to reach resolution with the FDA regarding a path to address the deficiencies in the NDA noted in the CRL and ADL, and the time and cost associated with such path;

•the sales price and the availability of adequate third-party reimbursement for IBSRELA and XPHOZAH, if approved;

•the manufacturing costs of IBSRELA and XPHOZAH;

•the selling and marketing costs associated with IBSRELA and XPHOZAH, if approved;

•our ability to maintain our existing collaboration partnerships and to establish additional collaboration partnerships, in-license/out-license, joint ventures or other similar arrangements and the financial terms of such agreements;

•the timing, receipt, and amount of sales of, or royalties on, tenapanor, if any;

•the cash requirements of any future acquisitions or discovery of product candidates;

•any clinical trials we are required to or decide to pursue for tenapanor or RDX013;

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•the time and cost necessary to respond to technological and market developments;

•the costs of filing, prosecuting, maintaining, defending and enforcing any patent claims and other intellectual property rights, including litigation costs and the outcome of such litigation, including costs of defending any claims of infringement brought by others in connection with the development, manufacture or commercialization of tenapanor or any of our product candidates; and

•the payment of interest and principal related to our loan and security agreement entered into with SLR Investment Corp. in February 2022.

Additional funds may not be available when we need them on terms that are acceptable to us, or at all. If adequate funds are not available to us on a timely basis, we may be required to delay, limit, reduce or terminate our commercialization of IBSRELA, our efforts to secure approval for XPHOZAH for the hyperphosphatemia indication, or clinical trials for tenapanor or RDX013. Additionally, our inability to access capital on a timely basis and on terms that are acceptable to us may force us to restructure certain aspects of our business or identify and complete one or more strategic collaborations or other transactions in order to fund the development or commercialization of IBSRELA or XPHOZAH through the use of alternative structures.

Our failure to meet the continued listing requirements of The Nasdaq Global Market could result in a de-listing of our common stock.

If we fail to satisfy the continued listing requirements of The Nasdaq Global Market ("Nasdaq") such as the minimum stockholders’ equity requirement or the minimum closing bid price requirement, Nasdaq may take steps to de-list our common stock. For example, on February 28, 2022 we received a letter from Nasdaq indicating that Nasdaq had determined that we had failed to comply with the minimum bid price requirement of Nasdaq Listing Rule 5550(a)(2). Nasdaq Listing Rule 5550(a)(2) requires that companies listed on the Nasdaq Global Market maintain a minimum closing bid price of at least $1.00 per share. In accordance with Nasdaq Listing Rule 5810(c)(3)(A), we have been provided with a period of 180 calendar days, or until August 29, 2022, to regain compliance with the minimum bid price requirement. We are monitoring the bid price of our common stock and will consider options available to us to achieve compliance. If we fail to maintain compliance with this requirement, or any other of the continued listing requirements of The Nasdaq Global Market, Nasdaq may take steps to de-list our common stock.

If Nasdaq de-lists our securities for trading on the Nasdaq or takes other actions with respect to our Nasdaq listing, we could face significant adverse consequences, including:

• a limited availability of market quotations for our common stock;

• reduced liquidity with respect to our common stock;

• reduced trading volume in and market price of our common stock;

• a limited amount of news and analyst coverage for our company; and

• a decreased ability to issue additional securities or obtain additional financing in the future.

Such a de-listing would likely have an adverse effect on the price of our common stock and would impair your ability to sell or purchase our common stock when you wish to do so. We may take actions to avoid such a de-listing or in the event of a de-listing, we may take actions to restore our compliance with Nasdaq’s listing requirements, but we can provide no assurance that any such action taken by us would allow our common stock to remain listed or to become listed again, stabilize the market price or improve the liquidity or trading volume of our common stock, prevent our common capitalization and stockholder’s equity from dropping below the Nasdaq minimum requirements, or prevent other future non-compliance with Nasdaq’s continued listing requirements.

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We have never generated any revenue from product sales and may never be profitable.

We received FDA approval for our NDA for tenapanor for the treatment of IBS-C in adults in September 2019, and we currently expect to launch IBSRELA in April 2022. We have no other products approved for sale and have received a CRL from the FDA for our NDA for the Hyperphosphatemia Indication and an Appeal Denied Letter (“ADL”) in response to our appeal of the CRL to the FDA Office of Cardiology, Hematology, Endocrinology and Nephrology (“OCHEN”). There can be no assurances that our NDA for tenapanor for the Hyperphosphatemia Indication will be approved for such indication or any other related indication. We have never generated any revenue from product sales. Our ability to generate revenue from product sales and achieve profitability depends on our ability to successfully commercialize IBSRELA; obtain approval by the FDA for the Hyperphosphatemia Indication, and subsequently successfully commercialize XPHOZAH for the Hyperphosphatemia Indication; and the ability of our collaboration partners to obtain regulatory approval to market tenapanor in their respective territories. There can be no assurances that we will generate sufficient product revenue from sales of IBSRELA and, if approved, XPHOZAH, to cover our expenses. Our ability to generate product revenue from sales or pursuant to milestone payments depends heavily on many factors, including but not limited to:

•our ability to successfully commercialize IBSRELA;

•obtaining market acceptance of IBSRELA as a viable treatment option for IBS-C;

•our ability to obtain and sustain an adequate level of coverage and reimbursement for IBSRELA by third-party payors;

•whether we are successful in our efforts under the FDR process to secure approval for our NDA for tenapanor for the Hyperphosphatemia Indication, or whether we are able during the FDR to reach resolution with the FDA regarding a path to addressing the deficiencies in our NDA noted in the CRL and ADL that is achievable in terms of clinical study design, time and cost;

•establishing and maintaining supply and manufacturing relationships with third parties that can provide an adequate (in amount and quality) supply of product to support the market demand for IBSRELA, and, if approved, XPHOZAH;

•addressing any competing technological and market developments;

•maintaining, protecting and expanding our portfolio of intellectual property rights, including patents, trade secrets, and know-how, and our ability to develop, manufacture and commercialize our product candidates and products without infringing intellectual property rights of others; and

•attracting, hiring, and retaining qualified personnel.

With respect to our commercialization of IBSRELA, and if we are successful in obtaining regulatory approval to market XPHOZAH, our revenue will be dependent, in part, upon the size of the markets in the U.S. and the label for which approval is or was granted, accepted price for the product, the ability to get reimbursement at any price. While there is significant uncertainty related to the insurance coverage and reimbursement of newly approved products in general in the United States, there is additional uncertainty related to insurance coverage and reimbursement for drugs, like XPHOZAH, which, if approved, will be marketed for the control of serum phosphorus in adult patients with CKD on dialysis or for another other related indication. If we are successful in obtaining regulatory approval to market XPHOZAH for such indication, our ability to generate and sustain future revenues from sales of tenapanor for such indication, may be dependent upon whether and when XPHOZAH, along with other oral ESRD related drugs without an injectable or intravenous equivalent, are bundled into the ESRD prospective payment system, and the manner in which such introduction into the ESRD prospective payment system may occur. See “Third-party payor coverage and reimbursement status of newly-approved products is uncertain. Failure to obtain or maintain adequate coverage and reimbursement for IBSRELA or XPHOZAH, if approved, could limit our ability to market those products and decrease our ability to generate revenue” below. Additionally, if the number of adult patients for IBSRELA or XPHOZAH, if approved, is not as significant as we estimate, the indication approved by regulatory authorities for XPHOZAH is narrower than we expect, coverage and reimbursement for either IBSRELA or XPHOZAH, if approved, are not available in the manner and to the extent we expect, or the reasonably accepted population for treatment is narrowed by competition, physician choice or treatment guidelines, we may not generate significant revenue from the sale of IBSRELA or XPHOZAH, if approved. Even if we achieve profitability in the future, we may not be able to sustain profitability in subsequent periods. Our failure to generate adequate revenue from product sales would likely depress our market value and could impair our ability to raise capital, expand our business, discover or develop other product candidates or continue our operations. A decline in the value of our common stock could cause our stockholders to lose all or part of their investment.

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Principal Risks Related to Our Business

We are substantially dependent on the successful launch and commercialization of IBSRELA for IBS-C, and there is no guarantee that we will achieve sufficient market acceptance for IBSRELA; secure adequate coverage and reimbursement for IBSRELA; or generate sufficient revenue from product sales of IBSRELA.

In November 2021, we announced plans to launch IBSRELA, our approved treatment for IBS-C in adults. We are investing a significant portion of our efforts and financial resources to prepare for and fund the commercialization of IBSRELA, which we currently expect to commence in April 2022. Our ability to successfully launch IBSRELA, and the overall commercial success of IBSRELA will depend on a number of factors, including the following:

•the ability of the third-party manufacturers we contract with to provide an adequate (in amount and quality) supply of product to support the launch and market demand for IBSRELA;

•our ability to obtain and sustain an adequate level of coverage and reimbursement for IBSRELA by third-party payors;

•the effectiveness of IBSRELA as a treatment for adult patients with IBS-C;

•the size of the treatable patient population;

•the effectiveness of our sales, market access and marketing efforts;

•the adoption of IBSRELA by physicians for the treatment of IBS-C, depends upon whether physicians view IBSRELA as a safe and effective treatment for adult patients with IBS-C;

•the availability, perceived advantages, relative cost, relative safety and relative efficacy of IBSRELA compared to alternative and competing treatments; and

•the prevalence and severity of adverse side effects of IBSRELA;

•our potential involvement in lawsuits in connection with enforcing intellectual property rights in and to IBSRELA;

•our potential involvement in third-party interference, opposition, derivation or similar proceedings with respect to our patent rights directed to IBSRELA, and avoiding other challenges to our patent rights and patent infringement claims; and

•a continued acceptable safety and tolerability profile of IBSRELA following approval.

Our potential to achieve revenue from the commercialization of IBSRELA and the amount of such potential revenue is subject to these and other factors, and may be unpredictable from quarter-to-quarter. If the number of patients in the market for IBSRELA or the price that the market can bear is not as significant as we estimate, or if we are not able to secure adequate physician and patient acceptance of IBSRELA or adequate coverage and reimbursement for IBSRELA, we may not generate sufficient revenue from sales of IBSRELA. Any failure of IBSRELA to achieve market acceptance, sufficient third-party coverage or reimbursement, or commercial success for would adversely affect our results of operations.

Our success is also dependent upon our ability to obtain regulatory approval for tenapanor for the control of serum phosphorus in adult patients with CKD on dialysis, and there can be no assurances that we will be successful in obtaining such regulatory approval.

Our success is also dependent upon our ability to obtain regulatory approval for tenapanor for the control of serum phosphorus in adult patients with CKD on dialysis. To date, we have invested a significant amount of our efforts and financial resources in the research and development of tenapanor for the control of serum phosphorus in adult patients with CKD on dialysis. On July 28, 2021, we received a CRL from the’FDA's Division of Cardiology and Nephrology (the “Division”) regarding our NDA for tenapanor for the control of serum phosphorus in adult patients with CKD on dialysis. According to the CRL, the FDA has determined that the magnitude of the treatment effect observed in our Phase 3 clinical trials was small and of unclear of clinical significance. Following an End-of-Review Type A meeting (“End of Review Meeting”) in October 2021, with the Division, we submitted a Formal Dispute Resolution Request (“FDRR”) in December 2021. The FDRR was focused on demonstrating that the data submitted in the NDA supported the clinical significance of the treatment effect of tenapanor. On February 4, 2022, we received an ADL from OCHEN. On February 18, 2022, we submitted an appeal of the ADL to the FDA’s

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Center for Drug Evaluation and Research, Office of New Drugs (“OND”). If accepted, we expect a decision on the appeal to the OND in April 2022. There can be no assurances that the Formal Dispute Resolution (“FDR”) process will result in approval of our NDA, or in a clear path to resubmission of our NDA that is achievable in terms of clinical study design, time and cost. As a result, the regulatory approval process for our NDA is highly uncertain. We may not obtain approval at all, and if we are able to obtain approval, the expense and time to do so could adversely impact our ability to successfully commercialize XPHOZAH, our business and our results of operations.

Even if we are successful in obtaining regulatory approval for tenapanor for control of serum phosphorus in adult patients with CKD on dialysis, the expense and time required to do so could adversely impact our ability to successfully commercialize XPHOZAH for the Hyperphosphatemia Indication.

We may not be successful in obtaining approval for tenapanor for the Hyperphosphatemia Indication, and if we are able to obtain approval, the expense and time to do so could adversely impact our ability to successfully commercialize XPHOZAH for the Hyperphosphatemia Indication, our business and our results of operations. If we are successful in obtaining approval for XPHOZAH for the Hyperphosphatemia Indication, the commercial success of XPHOZAH will depend on a number of factors, including the following:

•the ability of the third-party manufacturers we contract with to provide an adequate (in amount and quality) supply of product to support the market demand for both IBSRELA and XPHOZAH;

•whether or not the content and breadth of the label approved by the FDA for XPHOZAH may materially and adversely impact our ability to commercialize the product for the approved indication;

•whether or when XPHOZAH, along with other oral end-stage renal disease (“ESRD”) related drugs without an injectable or intravenous equivalent, are bundled into the ESRD prospective payment system, and the manner in which such introduction into the ESRD prospective payment system may occur;

•the prevalence and severity of adverse side effects of XPHOZAH;

•acceptance of XPHOZAH as safe, effective and well-tolerated by patients and the medical community, and, the extent to which the issuance of a CRL by the FDA has impacted the potential acceptance of XPHOZAH as safe, effective and well-tolerated;

•our ability to manage the commercialization of IBSRELA and XPHOZAH and the complex pricing and reimbursement negotiations that may arise with marketing the same product at different doses for separate indications;

•the availability, perceived advantages, relative cost, relative safety and relative efficacy of XPHOZAH compared to alternative and competing treatments;

•obtaining and sustaining an adequate level of coverage and reimbursement for XPHOZAH by third-party payors;

•our potential involvement in lawsuits in connection with enforcing intellectual property rights in and to XPHOZAH;

•our potential involvement in third-party interference, opposition, derivation or similar proceedings with respect to our patent rights, and avoiding other challenges to our patent rights and patent infringement claims; and

•a continued acceptable safety and tolerability profile of XPHOZAH following approval.

IBSRELA, and/or XPHOZAH, if approved and commercialized, may cause undesirable side effects or have other properties that could limit the commercial success of the product.

Undesirable side effects caused by IBSRELA, and/or XPHOZAH, if approved, could cause us or regulatory authorities to interrupt, delay or halt the commercialization of the product. To date, the most common adverse reactions reported in at least 2% of patients in IBSRELA-treated patients and at an incidence greater than placebo in the two Phase 3 trials include: diarrhea, abdominal distension, flatulence and dizziness. Despite our receipt of marketing approval for IBSRELA and the completion of our Phase 3 clinical program for XPHOZAH, the prevalence and/or severity of these or other side effects could result in a number of potentially significant negative consequences could occur, including:

•regulatory authorities may withdraw their approval of the product or seize the product;

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•we or a collaboration partner may be required to recall the product;

•additional restrictions may be imposed on the marketing of the particular product or the manufacturing processes for the product or any component thereof, including the imposition of a Risk Evaluation and Mitigation Strategy (“REMS”) which could require creation of a Medication Guide or patient package insert outlining the risks of such side effects for distribution to patients, a communication plan to educate healthcare providers of the drugs’ risks, as well as other elements to assure safe use of the product, such as a patient registry and training and certification of prescribers;

•we or a collaboration partner may be subject to fines, injunctions or the imposition of civil or criminal penalties;

•regulatory authorities may require the addition of new labeling statements, such as a “black box” warning or a contraindication;

•we could be sued and held liable for harm caused to patients;

•the product may become less competitive; and

•our reputation may suffer.

Any of the foregoing events could prevent us, or a collaboration partner, from achieving or maintaining market acceptance of IBSRELA, and/or XPHOZAH, if approved, and could result in the loss of significant revenue to us, which would materially and adversely affect our results of operations and business.

We have no prior experience in the marketing, sale and distribution of pharmaceutical products; and there are significant risks in building and managing a commercial organization.

Prior to the receipt of the CRL for our NDA for the Hyperphosphatemia Indication, we had made significant progress in the establishment of our sales, marketing, and access organizations. Many members of those teams had their positions eliminated by our restructuring plans adopted in August and October 2021. In November 2021, we announced our plans to commercialize IBSRELA and commenced our efforts to rebuild the critical components of the sales, marketing and access teams aligned to the IBSRELA commercial opportunity. As a company, we have no prior experience in building and managing a commercial organization, or in the marketing, sale and distribution of pharmaceutical products. There can be no assurances that we will be successful in our efforts to hire, retain, and incentivize qualified individuals, generate sufficient sales leads, provide adequate training to sales and marketing personnel, comply with regulatory requirements applicable to the marketing and sale of drug products and effectively manage a geographically dispersed sales and marketing team.

If we fail or are delayed in the development of our internal sales, marketing and distribution capabilities, we may need to delay the commercialization of IBSRELA, or commercialization could be adversely impacted.

Our operating activities may be restricted as a result of covenants related to the indebtedness under our loan and security agreement and we may be required to repay the outstanding indebtedness in an event of default, which could have a materially adverse effect on our business.

On February 23, 2022, we entered into a loan and security agreement with SLR Investment Corp. (the “Lender”) pursuant to which the Lender agreed to provide us a $50.0 million term loan facility with a maturity date of March 1, 2027. The loan was funded in the amount of $27.5 million on February 23, 2022 and the remaining $22.5 million may be funded upon the satisfaction of both of the following conditions precedent to funding (i) receipt from the FDA of approval of the NDA for tenapanor for the Hyperphosphatemia Indication on or prior to December 31, 2022 and (ii) our achievement of a minimum of $30.0 million in net product revenue calculated on a trailing six month basis. Until we have repaid all funded indebtedness, the loan and security agreement subjects us to various customary covenants, including requirements as to financial reporting and insurance and restrictions on our ability to dispose of our business or property, to change our line of business, to liquidate or dissolve, to enter into any change in control transaction, to merge or consolidate with any other entity or to acquire all or substantially all the capital stock or property of another entity, to incur additional indebtedness, to incur liens on our property, to pay any dividends or other distributions on capital stock other than dividends payable solely in capital stock, to redeem capital stock, to enter into licensing agreements, to engage in transactions with affiliates, and to encumber our intellectual property. Our business may be adversely affected by these restrictions on our ability to operate our business.

We are permitted to make interest only payments on the loan facility through March 2024, with principal repayments commencing on April 1, 2024, however, we may be required to repay the outstanding indebtedness under the loan facility if an

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event of default occurs under the loan and security agreement. An event of default will occur if, among other things, we fail to make payments under the loan and security agreement; we breach any of our covenants under the loan and security agreement, subject to specified cure periods with respect to certain breaches; the Lender determines that a material adverse change has occurred; we or our assets become subject to certain legal proceedings, such as bankruptcy proceedings; we are unable to pay our debts as they become due; or we default on contracts with third parties which would permit the Lender to accelerate the maturity of such indebtedness or that could have a material adverse change on us. We may not have enough available cash or be able to raise additional funds through equity or debt financings to repay such indebtedness at the time any such event of default occurs. In this case, we may be required to delay, limit, reduce or terminate our activities necessary to commercialize IBSRELA, and/or if approved, XPHOZAH, clinical trials for tenapanor or RDX013, the Lender could also exercise its rights as collateral agent to take possession of and to dispose of the collateral securing the term loans, which collateral includes substantially all of our property (excluding intellectual property, which is subject to a negative pledge). Our business, financial condition and results of operations could be materially adversely affected as a result of any of these events.

Third-party payor coverage and reimbursement status of newly commercialized products are uncertain. Failure to obtain or maintain adequate coverage and reimbursement for IBSRELA and XPHOZAH, if approved, could limit our ability to market those products and decrease our ability to generate revenue.

The pricing, coverage and reimbursement of IBSRELA and XPHOZAH, if approved, must be adequate to support a commercial infrastructure. The availability and adequacy of coverage and reimbursement by governmental and private payors are essential for most patients to be able to afford treatments. Sales of IBSRELA, and XPHOZAH, if approved and commercialized, will depend substantially, both domestically and abroad, on the extent to which the costs of the product will be paid for by health maintenance, managed care, pharmacy benefit, and similar healthcare management organizations, or reimbursed by government authorities, private health insurers, and other third-party payors. If coverage and reimbursement are not available, or are available only to limited levels, we, or our collaboration partners, may not be able to successfully commercialize IBSRELA, or XPHOZAH, if approved. Even if coverage is provided, the approved reimbursement amount may not be high enough to allow us to establish or maintain pricing sufficient to realize a return on our investment.

There is significant uncertainty related to the insurance coverage and reimbursement of newly approved products. In the United States, the principal decisions about coverage and reimbursement for new drugs are typically made by the Centers for Medicare & Medicaid Services (“CMS”), an agency within the United States Department of Health and Human Services responsible for administering the Medicare program, as CMS decides whether and to what extent a new drug will be covered and reimbursed under Medicare. Private payors tend to follow the coverage reimbursement policies established by CMS to a substantial degree. It is difficult to predict what CMS will decide with respect to reimbursement for products such as ours.

There is increased uncertainty related to insurance coverage and reimbursement for drugs, like XPHOZAH for the Hyperphosphatemia Indication, which, if approved, will be marketed for the control of serum phosphorus in adult patients with CKD on dialysis or for another other related indication. In January 2011, CMS implemented a new prospective payment system for dialysis treatment. Under the ESRD prospective payment system, CMS generally makes a single bundled payment to the dialysis facility for each dialysis treatment that covers all items and services routinely required for dialysis treatments furnished to Medicare beneficiaries in Medicare-certified ESRD facilities or at their home, including the cost of certain routine drugs. The inclusion of oral medications without injectable or intravenous equivalents in the bundled payment was initially delayed until January 1, 2014, and through several subsequent legislative actions was delayed until January 1, 2025. As a result, absent further legislation or regulation on this matter, beginning in 2025, oral ESRD-related drugs without injectable or intravenous equivalents may be included in the ESRD bundle and separate Medicare payment for these drugs will no longer be available, as is the case today under Medicare Part D. While it is too early to project the full impact that bundling may have on sales of XPHOZAH, if approved and commercialized, and on our business should XPHOZAH be brought into the bundle in 2025, or at any time, we may be unable to sell XPHOZAH for the Hyperphosphatemia Indication, if approved, to dialysis providers on a profitable basis if third-party payors reduce their current levels of payment, or if our costs of production are higher than levels necessary for an appropriate gross margin after payment of all discounts, rebates and chargebacks.

Outside the United States, international operations are generally subject to extensive governmental price controls and other market regulations, and we believe the increasing emphasis on cost-containment initiatives in Europe, Canada, Japan, China and other countries has and will continue to put pressure on the pricing and usage of IBSRELA and XPHOZAH, even if regulatory approval is received in such countries. In many countries, the prices of medical products are subject to varying price control mechanisms as part of national health systems. Other countries allow companies to fix their own prices for medicinal products, but monitor and control company profits. Additional foreign price controls or other changes in pricing regulation could restrict the amount that we are able to charge for our product candidates. Accordingly, in markets outside the United States, the reimbursement for our products may be reduced compared with the United States and may be insufficient to generate commercially reasonable revenue and profits.

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Moreover, increasing efforts by governmental and third-party payors in the United States and abroad to cap or reduce healthcare costs may cause such organizations to limit both coverage and the level of reimbursement for newly approved products and, as a result, these caps may not cover or provide adequate payment for our product candidates. We expect to experience pricing pressures in connection with the sale of IBSRELA, and if approved and commercialized, XPHOZAH, due to the trend toward managed healthcare, the increasing influence of health maintenance organizations, and additional legislative changes. The downward pressure on healthcare costs in general, particularly prescription drugs and surgical procedures and other treatments, has become very intense. As a result, increasingly high barriers are being erected to the entry of new products.

We rely completely on third parties to manufacture IBSRELA, XPHOZAH and RDX013. If they are unable to comply with applicable regulatory requirements, unable to source sufficient raw materials, experience manufacturing or distribution difficulties or are otherwise unable to manufacture sufficient quantities to meet demand, our commercialization of IBSRELA, and XPHOZAH, if approved and commercialized, and our development efforts for tenapanor and RDX013 may be materially harmed.

We do not currently have, nor do we plan to acquire, the infrastructure or capability internally to manufacture IBSRELA, or any of other our product candidates on a commercial scale, or to manufacture our drug supplies for use in the conduct of our nonclinical and clinical studies. The facilities used by our contract manufacturers to manufacture our drug supply are subject to inspection by the FDA. Our ability to control the manufacturing process of our product candidates is limited to the contractual requirements and obligations we impose on our contract manufacturer. Although they are contractually required to so do, we are completely dependent on our contract manufacturing partners for compliance with the regulatory requirements, known as current Good Manufacturing Practice requirements (“cGMPs”), for manufacture of both active drug substances and finished drug products.

The manufacture of pharmaceutical products requires significant expertise and capital investment. Manufacturers of pharmaceutical products often encounter difficulties in commercial production. These problems may include difficulties with production costs and yields, quality control, including stability of the product and quality assurance testing, and shortages of qualified personnel, as well as compliance with federal, state and foreign regulations and the challenges associated with complex supply chain management. Even if our contract manufacturers do not experience problems and commercial manufacturing is achieved, their maximum or available manufacturing capacities may be insufficient to meet commercial demand. Finding alternative manufacturers or adding additional manufacturers requires a significant amount of time and involves significant expense. New manufacturers would need to develop and implement the necessary production techniques and processes, which along with their facilities, would need to be inspected and approved by the regulatory authorities in each applicable territory. In addition, the raw materials necessary to make API for our products are acquired from a limited number of sources. Any delay or disruption in the availability of these raw materials could result in production disruptions, delays or higher costs with consequent adverse effects on us.

If our contract manufacturers fail to adhere to applicable GMP or other regulatory requirements, experience delays or disruptions in the availability of raw materials or experience manufacturing or distribution problems, we may suffer significant consequences, including the inability to meet our product requirements for our clinical development programs, and if tenapanor is commercialized for any indication, such events could result in product seizures or recalls, loss of product approval, fines and sanctions, reputational damage, shipment delays, inventory shortages, inventory write-offs and other product-related charges and increased manufacturing costs. As a result, or if maximum or available manufacturing capacities are insufficient to meet demand, our development or our commercialization efforts for IBSRELA, and/or XPHOZAH, if approved, may be materially harmed.

Additional Risks Related to Our Business and Industry

Clinical drug development involves a lengthy and expensive process with an uncertain outcome and the results of earlier studies and trials may not be predictive of future trial results.

Before obtaining marketing approval from regulatory authorities for the sale of our product candidates, we must conduct extensive clinical studies to demonstrate the safety and efficacy of the product candidates in humans. Clinical testing is expensive and can take many years to complete, and its outcome is inherently uncertain. Failure can occur at any time during the clinical trial process. The results of preclinical and clinical studies of our product candidates, including RDX013, may not be predictive of the results of later-stage clinical trials. An unexpected adverse event profile, or the results of drug-drug interaction studies, may present challenges for the future development and commercialization of a product candidate for a particular condition despite receipt of positive efficacy data in a clinical study. A number of companies in the pharmaceutical, biopharmaceutical and biotechnology industries have suffered significant setbacks in advanced clinical trials for similar

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indications that we are pursuing due to lack of efficacy or adverse safety profiles, notwithstanding promising results in earlier studies, and we cannot be certain that we will not face similar setbacks.

We could encounter delays in our future development of RDX013 if any clinical trials are suspended or terminated by us, by the IRBs of the institutions in which the trial is being conducted, or by the FDA or other regulatory authorities. Such authorities may suspend or terminate a clinical trial due to a number of factors, including failure to conduct the clinical trial in accordance with regulatory requirements or our clinical protocols, inspection of the clinical trial operations or trial site by the FDA or other regulatory authorities resulting in the imposition of a clinical hold, unforeseen safety issues or adverse side effects, failure to demonstrate a benefit from using a drug, changes in governmental regulations or administrative actions or lack of adequate funding to continue the clinical trial.

In addition, identifying and qualifying patients to participate in our RDX013 clinical trials is critical to the success of the clinical trials. The timing of our clinical trials depends, in part, on the speed at which we can recruit patients to participate in testing our product candidates. Patients may be unwilling to participate in our clinical studies because of concerns about adverse events observed with the current standard of care, competitor products and/or other investigational agents, in each case for the same indications and/or similar patient populations. In addition, patients currently receiving treatment with the current standard of care or a competitor product may be reluctant to participate in a clinical trial with an investigational drug, or our inclusion and exclusion criteria for our clinical trials may present challenges in identifying acceptable patients. As a result, the timeline for recruiting patients and conducting RDX013 clinical trials may be delayed. These delays could result in increased costs, delays in advancing our development of RDX013, or termination of the clinical studies altogether. Any of these occurrences may significantly harm our business, financial condition and prospects.

We will rely on third parties to conduct all of our nonclinical studies and clinical trials. If these third parties do not successfully carry out their contractual duties or meet expected deadlines, we may be unable to obtain regulatory approval for additional products or commercialize our product candidates.

We do not have the ability to independently conduct nonclinical studies or clinical trials. We rely on medical institutions, clinical investigators, contract laboratories, and other third parties, such as CROs, to conduct clinical trials on our product candidates. The third parties with whom we contract for execution of the clinical trials play a significant role in the conduct of these trials and the subsequent collection and analysis of data. However, these third parties are not our employees, and except for contractual duties and obligations, we control only certain aspects of their activities and have limited ability to control the amount or timing of resources that they devote to our programs. Although we rely, and will continue to rely, on these third parties to conduct our nonclinical studies and our clinical trials, we remain responsible for ensuring that each of our studies and clinical trials is conducted in accordance with the applicable protocol, legal, regulatory and scientific standards and our reliance on third parties does not relieve us of our regulatory responsibilities. We, and these third parties are required to comply with current GLPs for nonclinical studies, and good clinical practices (“GCPs”) for clinical studies. GLPs and GCPs are regulations and guidelines enforced by the FDA, the Competent Authorities of the Member States of the European Economic Area (“EEA”) and comparable foreign regulatory authorities for all of our products in nonclinical and clinical development, respectively. Regulatory authorities enforce GCPs through periodic inspections of trial sponsors, principal investigators and trial sites. If we or any of our third-party contractors fail to comply with applicable regulatory requirements, including GCPs, the clinical data generated in our clinical trials may be deemed unreliable and the FDA, the European Medicines Agency (“EMA”), or comparable foreign regulatory authorities may require us to perform additional clinical trials before approving our marketing applications. There can be no assurance that upon inspection by a given regulatory authority, such regulatory authority will determine that any of our clinical trials comply with GCP regulations. In addition, our clinical trials must be conducted with product produced under cGMP regulations. Our failure to comply with these regulations may require us to repeat clinical trials, which would delay the regulatory approval process.

We face substantial competition, and our competitors may discover, develop or commercialize products faster or more successfully than us.

The biotechnology and pharmaceutical industries are highly competitive, and we face significant competition from companies in the biotechnology, pharmaceutical and other related markets that are researching and marketing products designed to address diseases that we are currently developing products to treat. If approved for marketing by the FDA or other regulatory agencies, tenapanor, as well as our other product candidates, would compete against existing treatments.

For example, numerous treatments exist for constipation and the constipation component of IBS-C, many of which are over-the-counter. These include psyllium husk (such as Metamucil), methylcellulose (such as Citrucel), calcium polycarbophil (such as FiberCon), lactulose (such as Cephulac), polyethylene glycol (such as MiraLax), sennosides (such as Exlax), bisacodyl

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(such as Ducolax), docusate sodium (such as Colace), magnesium hydroxide (such as Milk of Magnesia), saline enemas (such as Fleet), and sorbitol. These agents are generally inexpensive and work well to temporarily relieve constipation.

We are aware of four prescription products marketed for certain patients with IBS-C, including Linzess (linaclotide), Amitiza (lubiprostone), Trulance (plecanatide) and Zelnorm (tegaserod maleate).

Additionally, XPHOZAH, if approved for the Hyperphosphatemia Indication will compete with phosphate binders used for the same or similar indication`. If approved, our label for XPHOZAH may include data comparing the effectiveness of tenapanor to phosphate binders used for the same indication. The various types of phosphate binders commercialized in the United States include the following:

•Calcium carbonate (many over-the-counter brands including Tums and Caltrate);

•Calcium acetate (several prescription brands including PhosLo and Phoslyra);

•Lanthanum carbonate (Fosrenol);

•Sevelamer hydrochloride (Renagel);

•Sevelamer carbonate (Renvela);

•Sucroferric oxyhydroxide (Velphoro); and

•Ferric citrate (Auryxia).

All of the phosphate binders listed above are available as generics in the U.S., with the exception of Velphoro and Auryxia. In addition to the currently available phosphate binders, we are aware of at least two other binders in development, including fermagate (Alpharen), an iron-based binder in Phase 3 being developed by Opko Health, Inc., and PT20, an iron-based binder in Phase 3 being developed by Shield Therapeutics.

It is possible that our competitors' drugs may be less expensive and more effective than our product candidates, or that will render our product candidates obsolete. It is also possible that our competitors will commercialize competing drugs or treatments before we or our collaboration partners can launch any products developed from our product candidates. We also anticipate that we will face increased competition in the future as new companies enter into our target markets.

Many of our competitors have materially greater name recognition and financial, manufacturing, marketing, research and drug development resources than we do. Additional mergers and acquisitions in the biotechnology and pharmaceutical industries may result in even more resources being concentrated in our competitors. Large pharmaceutical companies in particular have extensive expertise in preclinical and clinical testing and in obtaining regulatory approvals for drugs. In addition, academic institutions, government agencies, and other public and private organizations conducting research may seek patent protection with respect to potentially competitive products or technologies. These organizations may also establish exclusive collaboration partnerships or licensing relationships with our competitors.

We may experience difficulties in managing our current activities and growth given our level of managerial, operational, financial and other resources.

While we have continued to work to optimize our management composition, personnel and systems to support our current activities for future growth, these resources may not be adequate for this purpose. Our need to effectively execute our business strategy requires that we:

•manage any commercialization activities in which we may engage effectively;

•manage our clinical trials effectively;

•manage our internal development efforts effectively while carrying out our contractual obligations to licensors, contractors, collaborators, government agencies and other third parties;

•continue to improve our operational, financial and management controls, reporting systems and procedures; and

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•retain and motivate our remaining employees and potentially identify, recruit, and integrate additional employees.

If we are unable to maintain or expand our managerial, operational, financial and other resources to the extent required to manage our development and commercialization activities, our business will be materially adversely affected.

If product liability lawsuits are brought against us, we may incur substantial liabilities and may be required to limit commercialization of IBSRELA, and/or XPHOZAH, if approved.

We face an inherent risk of product liability as a result of the clinical testing of our product candidates and will face an even greater risk following the commercial launch of IBSRELA in April 2022. For example, we may be sued if any product we develop allegedly causes injury or is found to be otherwise unsuitable during product testing, manufacturing, marketing or sale. Any such product liability claims may include allegations of defects in manufacturing, defects in design, a failure to warn of dangers inherent in the product, negligence, strict liability, and a breach of warranties. Claims could also be asserted under state consumer protection acts. If we cannot successfully defend ourselves against product liability claims, we may incur substantial liabilities or be required to limit commercialization of our product candidates. Even successful defense would require significant financial and management resources. Regardless of the merits or eventual outcome, liability claims may result in:

•decreased demand for the product;

•injury to our reputation;

•withdrawal of clinical trial participants;

Source: SEC EDGAR (public domain) · 10-K for the period ended 2021-12-31, filed 2022-02-28 · accession 0001628280-22-004226

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