STRO US Equity☆

Item 7. Management’s Discussion and Analysis of Financial Condition and Results of Operations

The following discussion should be read in conjunction with the attached financial statements and notes thereto. This Annual Report on Form 10-K, including the following sections, contains forward-looking statements within the meaning of the federal securities laws. These statements are subject to risks and uncertainties that could cause actual results and events to differ materially from those expressed or implied by such forward-looking statements. For a detailed discussion of these risks and uncertainties, see the “Risk Factors” section in Item 1A of this Annual Report on Form 10-K. We caution the reader not to place undue reliance on these forward-looking statements, which reflect management’s analysis only as of the date of this Form 10-K. We undertake no obligation to update forward-looking statements, which reflect events or circumstances occurring after the date of this Form 10-K.

Overview

We are a clinical-stage oncology company developing site-specific and novel-format antibody drug conjugates, or ADCs, enabled by our proprietary integrated cell-free protein synthesis platform, XpressCF®, and our site specific conjugation platform, XpressCF+®. We aim to design and develop therapeutics using the most relevant and potent modalities, including ADCs, bispecific ADCs, immunostimulatory ADCs, or iADCs, dual conjugate ADCs, or ADC2s, and cytokine derivatives. Our molecules are directed primarily against clinically validated targets where the current standard of care is suboptimal. We believe that our platform allows us to accelerate the discovery and development of potential first-in-class and/or best-in-class molecules by enabling the rapid and systematic evaluation of protein structure-activity relationships to create optimized homogeneous product candidates. Our mission is to transform the lives of patients by creating medicines with improved therapeutic profiles for areas of unmet need.

Once identified, production of protein drug candidates can be rapidly and predictably scaled in our current Good Manufacturing Practices, or cGMP, compliant manufacturing facility. We have the ability to manufacture our proprietary cell-free extract that supports our production of proteins on a large scale using a semi-continuous fermentation process. Ourmost advanced product candidate is STRO-002, or luveltamab tazevibulin, or luvelta, an ADC directed against folate receptor-alpha, or FolRα, for patients with FolRα-expressing cancers, including ovarian cancer.

Luvelta was designed and optimized for an improved therapeutic index by placing a precise number of linker-warheads at four specific locations within the antibody using our proprietary XpressCF+® platform. Our first Phase 1 trial for luvelta is an open-label study evaluating luvelta as a monotherapy for patients with ovarian and endometrial cancers. This trial is being conducted in two-parts, dose escalation and dose expansion. The primary objectives of the clinical trial are to determine the safety and tolerability profile, to define the recommended Phase 2 dose level and interval and to evaluate preliminary anti-tumor activity. Our secondary objectives are to characterize the human pharmacokinetics and additional safety, tolerability and efficacy measures.

Our next most advanced product candidate is STRO-001, an optimally designed ADC directed against the cancer target CD74, for multiple myeloma and NHL. STRO-001 was designed and optimized for maximal therapeutic index by placing linker-warheads at specific locations within the antibody using our proprietary XpressCF+® platform. The Phase 1 trial for STRO-001 is an open-label study evaluating STRO-001 as a monotherapy for patients with multiple myeloma and NHL. The trial is being conducted in two parts: dose escalation and dose expansion. The primary objectives of the trial are to determine the safety and tolerability profile of STRO-001, to determine the recommended Phase 2 dose level and interval and to evaluate preliminary anti-tumor activity. Our secondary objectives are to characterize the human pharmacokinetics of STRO-001 and additional safety, tolerability and efficacy measures.

In 2019, we began enrolling patients in a Phase 1 trial of luvelta that focused on ovarian and endometrial cancers. The dose escalation portion of the luvelta Phase 1 trial has been completed and the dose expansion portion of the trial to assess the efficacy, safety and tolerability of luvelta is ongoing. In January 2023,we reported preliminary final results from the dose-expansion cohort. The data from the dose-escalation and dose expansion cohorts suggested that luvelta exhibited a manageable safety profile together with promising preliminary efficacy data in the tested patient population. In August 2021, Luvelta was granted Fast Track designation by the U.S. Food and Drug Administration, or FDA, for the treatment of patients with platinum-resistant epithelial ovarian, fallopian tube, or primary peritoneal cancer who have received one to three prior lines of systemic therapy. In mid-2022, we discussed with the FDA appropriate trial designs for a registration-directed trial of luvelta to potentially

support accelerated approval. We expect to begin a registration-directed trial of luvelta for platinum-resistant ovarian cancer in the first half of 2023.

In addition, we have been offering compassionate use of luvelta to treat pediatric patients with relapsed/refractory CBF/GLIS AML, commonly known as RAM phenotype AML. Compassionate use data showed anti-leukemic activity of luvelta in pediatric patients with relapsed/refractory CBF/GLIS AML and was presented at the 64th American Society of Hematology Annual Meeting and Exposition (ASH 2022). The data showed that luvelta was well tolerated as a monotherapy agent and in combination with standard cancer therapies. Luvelta was granted Orphan Drug Designation by the FDA in December 2022 in this pediatric patient population.

We have completed enrollment for STRO-001 dose escalationin a Phase 1 trial for multiple myeloma and NHL. STRO-001 has been generally well-tolerated and no ocular toxicity signals have been observed, with no patients receiving prophylactic corticosteroid eye drops. We have completed dose escalation in the STRO-001 Phase 1 trial following identification of the maximum tolerated dose. In October 2021, we granted BioNova, an option to exclusively license the right to develop and commercialize STRO-001 in Greater China, or the BioNova Option Agreement. In February 2023, BioNova announced that the first patient had been dosed in the Phase 1 clinical trial of STRO-001.

We also have a preclinical product candidate - STRO-003, which is a single homogeneous ADC directed against an anti-Receptor tyrosine kinase-like orphan receptor 1, or ROR1, which we intend to develop for the treatment of solid tumors. Preparations are underway for IND enabling studies for STRO-003, which we expect will be completed in the first quarter of 2024. We expect to begin Phase 1 safety studies of STRO-003 in 2024.

Enabled through our proprietary XpressCF® and XpressCF+®platforms, we have entered into multi-target, product-focused collaborations with leading pharmaceutical and biotechnology companies in the field of oncology, including an immunostimulatory antibody-drug conjugates collaboration with Astellas, a cytokine derivatives collaboration with Merck; a B Cell Maturation Antigen, or BCMA, ADC collaboration with BMS; a MUC1-EGFR ADC collaboration with EMD Serono;BioNova; and Tasly. Our XpressCF® and XpressCF+® platforms have also supported Vaxcyte, focused on discovery and development of vaccines for the treatment and prophylaxis of infectious disease. In the fourth quarter of 2022, Vaxcyte announced positive topline data from a Phase 1/2 clinical proof-of-concept study of its lead product candidate, VAX-24, its 24-valent pneumococcal conjugate vaccine candidate, under investigation for the prevention of invasive pneumococcal disease in adults aged 18-64.Also in the fourth quarter of 2022, we entered into an agreement with Vaxcyte, granting it an option to access expanded rights to develop and manufacture cell-free extract for use in development and manufacture of its vaccine products, among certain other rights.

Since the commencement of our operations, we have devoted substantially all of our resources to performing research and development and manufacturing activities in support of our own product development efforts and those of our collaborators, raising capital to support and expand such activities and providing general and administrative support for these operations. We have funded our operations to date primarily from upfront, milestone and other payments under our collaboration agreements with BMS, Merck, Astellas, EMD Serono, Vaxcyte, BioNova, and Tasly, the issuance and sale of redeemable convertible preferred stock, our initial public offering, or IPO, follow-on public offerings of common stock, sales of our common stock through our ATM Facility, and debt proceeds.

We do not have any products approved for commercial sale and have not generated any revenue from commercial product sales. We had a loss from operations of $128.9 million and a net loss of $119.2 million for the year ended December 31, 2022, which net loss included the non-operating, unrealized gain of $12.1 million related to our holdings of Vaxcyte common stock. We had a loss from operations of $98.5 million and net loss of $105.5 million, which net loss included the non-operating, unrealized loss of $4.5 million related to our holdings of Vaxcyte common stock, for the year ended December 31, 2021. Substantially all of our losses have resulted from expenses incurred in connection with our research and development programs and from general and administrative costs associated with our operations. We cannot assure you that we will have net income or that we will generate positive cash flow from operating activities in the future. As of December 31, 2022, we had an accumulated deficit of $452.6 million. We do not expect to generate any revenue from commercial product sales unless and until we successfully complete development and obtain regulatory approval for one or more of our product candidates, which we expect will take a number of years. If we obtain regulatory approval for any of our product candidates, we expect to incur significant commercialization expenses related to product sales, access, marketing, manufacturing and distribution. We expect our operating expenses to significantly increase as we continue to develop, and seek regulatory approvals for, our product candidates, engage in other research and development activities, expand our pipeline of product candidates, continue to develop our manufacturing facility and capabilities, maintain and expand our intellectual property portfolio, seek regulatory and marketing approval for any product candidates that we may develop, acquire or in-license other assets or technologies, ultimately establish a sales, marketing and distribution infrastructure to commercialize any products for which we may obtain marketing approval, and operate as a public company. Our net losses may fluctuate significantly from quarter-to-quarter and year-to-year, depending on the timing of our clinical trials, our expenditures on other research and development activities and the timing of achievement and receipt of upfront, milestones and other collaboration agreement payments.

A discussion and analysis of our financial condition, results of operations, and cash flows for the year ended December 31, 2020 is included in Item 7 of Part II “Management’s Discussion and Analysis of Financial Condition and Results of Operations” in our Annual Report on Form 10-K for the year ended December 31, 2021 filed with the SEC on February 28, 2022.

Financial Operations Overview

Revenue

We do not have any products approved for commercial sale and have not generated any revenue from commercial product sales. Our total revenue to date has been generated principally from our collaboration and license agreements with BMS, Merck, Astellas, EMD Serono, Vaxcyte, BioNova and Tasly, and to a lesser extent, from manufacturing, supply and services and materials we provide to the above collaborators.

We derive revenue from collaboration arrangements, under which we may grant licenses to our collaboration partners to further develop and commercialize our proprietary product candidates. We may also perform research and development activities under the collaboration agreements. Consideration under these contracts generally includes a nonrefundable upfront payment, development, regulatory and commercial milestones and other contingent payments, and royalties based on net sales of approved products. Additionally, the collaborations may provide options for the customer to acquire from us materials and reagents, clinical product supply or additional research and development services under separate agreements. We assess which activities in the collaboration agreements are considered distinct performance obligations that should be accounted for separately. We develop assumptions that require judgement to determine whether the license to our intellectual property is distinct from the research and development services or participation in activities under the collaboration agreements.

At the inception of each agreement, we determine the arrangement transaction price, which includes variable consideration, based on the assessment of the probability of achievement of future milestones and contingent payments and other potential consideration. We recognize revenue over time by measuring our progress towards the complete satisfaction of the relevant performance obligation using an appropriate input or output method based on the nature of the service promised to the customer.

For arrangements that include multiple performance obligations, we allocate the transaction price to the identified performance obligations based on the standalone selling price, or SSP, of each distinct performance obligation. In instances where SSP is not directly observable, we develop assumptions that require judgment to determine the SSP for each performance obligation identified in the contract. These key assumptions may include

full-time equivalent, or FTE, personnel effort, estimated costs, discount rates and probabilities of clinical development and regulatory success.

Please see further discussion on the revenue recognition treatment of performance obligations under Critical Accounting Policies and Estimates.

Operating Expenses

Research and Development

Research and development expenses represent costs incurred in performing research, development and manufacturing activities in support of our own product development efforts and those of our collaborators, and include salaries, employee benefits, stock-based compensation, laboratory supplies, outsourced research and development expenses, professional services and allocated facilities-related costs. We expense both internal and external research and development costs as they are incurred. Nonrefundable advance payments for services that will be used or rendered for future research and development activities are recorded as prepaid expenses and recognized as expenses as the related services are performed.

We expect our research and development expenses to increase in the future as we advance our product candidates into and through preclinical studies and clinical trials, pursue regulatory approval of our product candidates, expand our pipeline of product candidates and continue to develop our manufacturing facility and capabilities. The process of conducting the necessary preclinical and clinical research to obtain regulatory approval is costly and time consuming. The actual probability of success for our product candidates may be affected by a variety of factors including: the safety and efficacy of our product candidates, early clinical data, investment in our clinical programs, the ability of collaborators to successfully develop our licensed product candidates, competition, manufacturing capability and commercial viability. We may never succeed in achieving regulatory approval for any of our product candidates. As a result of the uncertainties discussed above, we are unable to determine the duration and completion costs of our research and development projects or when and to what extent we will generate revenue from the commercialization and sale of our product candidates.

The following table summarizes our research and development expenses incurred during the periods indicated. The internal costs include personnel, facility costs and research and scientific related activities associated with our pipeline. The external program costs reflect external costs attributable to our clinical development candidates and preclinical candidates selected for further development. Such expenses include third-party costs for preclinical and clinical studies and research, development and manufacturing services, and other consulting costs.

Year ended December 31,

(in thousands)

Internal costs:

External Program Costs:

Toxicology and translational science 862 1,227

Process and product development 642 314

General and Administrative

Our general and administrative expenses consist primarily of personnel costs, expenses for outside professional services, including legal, human resources, audit, accounting and tax services and allocated facilities-related costs. Personnel costs include salaries, employee benefits and stock-based compensation. We expect to incur additional expenses operating as a public company, including expenses related to compliance with the rules and regulations of the SEC and listing standards applicable to companies listed on the Nasdaq Global Market, additional insurance expenses, investor relations activities and other administrative and professional services. We also expect to increase the size of our administrative function and our general and administrative expenses to support the anticipated growth of our business, and as we continue to advance our product candidates into and through the clinic.

Interest Income

Interest income consists primarily of interest earned on our invested funds.

Unrealized Gain (Loss) on Equity Securities

Unrealized gain (loss) on equity securities consists of the remeasurement of our investment in Vaxcyte common stock.

Interest and Other Income (Expense), Net

Interest expense includes interest incurred on our debt and amortization of debt issuance costs, including accretion of the final payment. Additionally, we identified a financing component under the Astellas Agreement and recorded interest expense associated with the upfront payment. Other income (expense) includes changes in values attributable to the arrangement with our Call Option Plan whereby we granted certain employee options to purchase shares of Vaxcyte common stock, and realized gain (loss) on the equity securities.

Income Taxes

We recorded a foreign income tax charge of $2.5 million due to a withholding tax in China on an upfront license fee payment received from Tasly for the year ended December 31, 2022. All other income tax charges and benefits during the years ended December 31, 2022 and 2021 have been immaterial, primarily due to the net loss in each year.

Our deferred assets continue to be subject to full valuation allowance for the tax years ended December 31, 2022 and 2021. A valuation allowance is recorded when it is more likely than not that all or some portion of the deferred income tax assets will not be realized. We regularly assess the need for a valuation allowance against our deferred income tax assets by considering both positive and negative evidence related to whether it is more likely than not that our deferred income tax assets will be realized. In evaluating our ability to recover our deferred income tax assets within the jurisdiction from which they arise, we consider all available positive and negative evidence, including scheduled reversals of deferred income tax liabilities, future tax rates, projected future taxable income, tax-planning strategies, and results of recent operations.

Comparison of the Years Ended December 31, 2022 and 2021

Year ended December 31, Change

(in thousands)

Operating expenses:

Interest and other income (expense), net (3,346 ) (3,137 ) (209 ) 7 %

Provision for income taxes 2,500 - 2,500 *

*Percentage not meaningful

Revenue

We have recognized revenue as follows during the indicated periods:

Year Ended December 31, Change

(in thousands)

Astellas Pharma Inc. (“Astellas”) 10,897 - 10,897 *

BioNova Pharmaceuticals, Ltd. (“BioNova”) 4,000 - 4,000 *

Tasly Biopharmaceuticals Co., Ltd. (“Tasly”) 25,000 - 25,000 *

*Percentage not meaningful

Total revenue increased by $5.9 million, or 10%, during the year ended December 31, 2022 as compared to the year ended December 31, 2021. This was primarily due to an earned $25.0 million upfront payment under the Tasly License Agreement, revenue from Astellas of $10.9 million, of which $3.9 million was from the ongoing performance related to partially unsatisfied performance obligations, $5.1 million was from the financing component related to the Astellas Agreement, and $1.9 million was from research and development services, revenue from BioNova of $4.0 million from the satisfaction of the performance obligation under the BioNova Option Agreement, and a $0.8 million increase in Vaxcyte revenue. These increases were partially offset by a $31.2 million decrease from Merck, related to a $13.3 million decrease from the 2021 completion of the performance obligations associated with the first and second target programs under the 2018 Merck Agreement, full recognition of $6.0 million of revenue earned in the first quarter of 2021 associated with the contingent third target program upon the termination of the related performance obligation, recognition of a $15.0 million contingent payment earned in the second quarter of 2021 for the initiation of the first IND-enabling toxicology study under the first program in the collaboration, a decrease of $3.2 million in research and development services and materials supply, a decrease of $3.1 million in manufacturing activities supporting clinical trial supply, and a decrease of $0.6 million due to the absence in 2022 of the financing component related to the 2018 Merck Agreement, partially offset by a $10.0 million contingent payment earned in the third quarter of 2022 with the first patient dosed in a Phase 1 study of an investigational candidate under the first program in the collaboration. EMD Serono revenue decreased by $1.9 million primarily due to a $2.0 million contingent payment earned in the second quarter of 2021, partially offset by a $0.1 million increase in 2022 materials supply and manufacturing activities supporting clinical trial supply. BMS revenue decreased by $1.7 million primarily due to a decrease of $3.7 million in research and development services and materials supply, partially offset by a $2.0 million increase in manufacturing activities supporting clinical trial supply.

Research and Development Expense

Research and development expense increased by $32.8 million, or 31%, during the year ended December 31, 2022 as compared to the year ended December 31, 2021. The overall increase was due primarily to increases of $11.6 million in personnel-related expenses due to higher headcount, $11.0 million in laboratory supplies and preclinical research and clinical development expenses, $10.5 million in consulting and outside services, and $0.5 million in travel, equipment and office-related expenses, partially offset by a $0.8 million decrease in facilities-related expenses.

General and Administrative Expense

General and administrative expense increased by $3.5 million, or 6%, during the year ended December 31, 2022 as compared to the year ended December 31, 2021. The increase was due primarily to increases of $2.2 million in personnel-related expenses due to higher headcount, $1.3 million in external services, $1.2 million in equipment and office-related expenses, and $0.3 million in travel-related expenses, partially offset by a $1.5 million decrease in facilities-related expenses.

Interest Income

Interest income increased by $2.9 million during the year ended December 31, 2022 as compared to the year ended December 31, 2021, due primarily to higher average investment balances and higher average rates of return in 2022.

Unrealized Gain / (Loss) on Equity Securities

Unrealized gain on equity securities was $12.1 million during the year ended December 31, 2022 as compared to an unrealized (loss) of $4.5 million for the year ended December 31, 2021. The unrealized gain (loss) on equity securities in each period was entirely due to the remeasurement of the estimated fair value of our investment in Vaxcyte common stock.

Interest and Other Income (Expense), Net

Interest and other income (expense), net, increased by $0.2 million during the year ended December 31, 2022 as compared to the year ended December 31, 2021, due primarily to the increase of $5.1 million from the financing component related to the Astellas Agreement, partially offset by a recognized gain of $4.1 million on

equity securities during the year ended December 31, 2022, a decrease of $0.6 million due to the absence of the financing component in the year ended December 31, 2022 related to the 2018 Merck Agreement, and a decrease of $0.2 million in interest incurred on our outstanding loan.

Liquidity and Capital Resources

Sources of Liquidity

We have incurred significant net losses to date. We have also incurred negative cash flows from operations in the years prior to 2022. Our operations have been funded primarily by payments received from our collaborators, and net proceeds from equity sales and debt. As of December 31, 2022, we had $302.3 million in cash, cash equivalents and marketable securities, equity securities of $32.0 million, outstanding debt of $16.3 million and an accumulated deficit of $452.6 million.

At-The-Market Sales

During the year ended December 31, 2022, we sold an aggregate of 10,285,160 shares of our common stock through our ATM Facility pursuant to the Sales Agreement with Jefferies. The gross proceeds from these sales were approximately $58.3 million, before deducting fees of approximately $2.0 million, resulting in net proceeds of approximately $56.3 million.

Upfront Payment from Astellas

In June 2022, we entered into a License and Collaboration Agreement with Astellas, for the development of immunostimulatory antibody-drug conjugates for up to three biological targets, to be identified by Astellas. Pursuant to the agreement with Astellas, we received from Astellas a one-time, nonrefundable, non-creditable, upfront payment of $90.0 million during the year ended December 31, 2022.

Upfront Payment from Tasly

During the year ended December 31, 2022, we earned a $25.0 million nonrefundable upfront payment from Tasly under the Tasly License Agreement to grant Tasly an exclusive license to develop and commercialize luvelta in Greater China. The upfront payment, net of a withholding tax of $2.5 million, resulted in a net payment to us of $22.5 million received during the year ended December 31, 2022.

Upfront Payment from Vaxcyte and Vaxcyte Equity Ownership

In December 2022, we entered into a letter agreement (the “Vaxcyte Agreement”) with Vaxcyte under which the Company granted to Vaxcyte (i) authorization to enter into an agreement with an independent alternate contract manufacturing organization, or CMO, to source cell-free extract solely for the products it licensed from the us, allowing Vaxcyte to have direct oversight over financial and operational aspects of the relationship with the CMO, and (ii) a right, but not an obligation, to obtain certain exclusive rights to internally manufacture and/or source extract from certain CMOs and the right to independently develop and make improvements to extract for use in connection with the exploitation of certain vaccine compositions (the “Option”).

Pursuant to the Vaxcyte Agreement, we received from Vaxcyte a one-time, nonrefundable, non-creditable, upfront payment of $10.0 million in cash, and 167,780 shares of Vaxcyte’s common stock with a fair value of $7.5 million at the date of the transaction in December 2022.

As of December 31, 2022, we held 667,780 shares of Vaxcyte common stock, which include the 167,780 shares received from Vaxcyte under the Vaxcyte Agreement. The estimated fair value of Vaxcyte common stock was $32.0 million as of December 31, 2022. During the year ended December 31, 2022, we sold 1,058,434 shares of Vaxcyte common stock for net proceeds of $28.7 million.

Contingent Payments from Merck

In July 2022, the first patient was dosed in a Phase 1 study of an investigational candidate resulting from the 2018 Merck Agreement for the first program in our collaboration to develop novel cytokine derivative therapeutics for cancer. As a result of this achievement, we earned and received a $10.0 million contingent payment from Merck during the year ended December 31, 2022.

During the year ended December 31, 2021, we earned and received a $15.0 million contingent payment from Merck for the initiation of an IND enabling toxicology study for the first program in our collaboration to develop novel cytokine derivative therapeutics for cancer.

Term Loan

On February 28, 2020, or the Effective Date, we entered into a loan and security agreement, or the Loan and Security Agreement, with Oxford Finance LLC, or Oxford, as the collateral agent and a lender, and Silicon Valley Bank, as a lender, together with Oxford, the Lenders, pursuant to which the Lenders have agreed to lend us up to an aggregate of $25.0 million, or the Term A Loan. Upon entering into the Loan and Security Agreement, we borrowed $25.0 million from the Lenders, with approximately $9.6 million of such amount applied to the repayment of the outstanding principal, interest and final payment fees owed pursuant to the prior loan and security agreement dated August 4, 2017.

In June 2022, we entered into an amendment to the LSA with Oxford and SVB (the “LSA Amendment”). The LSA Amendment added a financial covenant that requires us to maintain a minimum unrestricted cash balance of $10.0 million. We were in compliance with the financial covenant under the LSA Amendment as of December 31, 2022.

The proceeds from the Term A Loan under the Loan and Security Agreement may be used to satisfy our future working capital needs and to fund our general business requirements. Our obligations under the Loan and Security Agreement are secured by all our assets, other than our intellectual property. We have also agreed not to encumber our intellectual property assets, except as permitted by the Loan and Security Agreement.

The Term A Loan matures on March 1, 2024, or the Maturity Date, and was interest-only through March 1, 2022, followed by 24 equal monthly payments of principal and interest. The Term A Loan will bear interest at a floating per annum rate equal to the greater of (i) 8.07% or (ii) the sum of (a) the greater of (1) the thirty (30) day U.S. LIBOR rate reported in the Wall Street Journal on the last business day of the month that immediately precedes the month in which the interest will accrue or (2) 1.67%, plus (b) 6.40%.

We will be required to make a final payment of 3.83% of the original principal amount of the Term A Loan drawn, payable on the earlier of (i) the Maturity Date, (ii) the acceleration of the Term A Loan, or (iii) the prepayment of the Term A Loan, or the Final Payment. We may prepay all, but not less than all, of the Term A Loan upon 30 days’ advance written notice to Oxford, provided that we will be obligated to pay a prepayment fee equal to (i) 3.00% of the principal amount of the Term A Loan prepaid on or before the first anniversary of the applicable funding date, or (ii) 2.00% of the principal amount of the Term A Loan prepaid between the first and second anniversary of the applicable funding date, or (iii) 1.00% of the principal amount of the Term A Loan prepaid thereafter, and prior to the Maturity Date, each, a Prepayment Fee.

The Loan and Security Agreement contains customary affirmative and restrictive covenants, including covenants regarding incurrence of additional indebtedness or liens, investments, transactions with affiliates, delivery of financial statements, maintenance of inventory, payment of taxes, maintenance of insurance, protection of intellectual property rights, dispositions of property, business combinations or acquisitions, among other customary covenants. We are also restricted from paying dividends or making other distributions or payments on our capital stock, subject to limited exceptions. The Loan and Security Agreement provides that an event of default will occur if, among other triggers, there occurs any circumstances that could reasonably be expected to result in a material adverse change in our business, or operations or condition (financial or otherwise) or a material impairment of the prospect of us to repay any portion of our obligations under the Loan and Security Agreement. The Loan and Security Agreement previously included a covenant requiring us to keep substantially all of our cash and investments with SVB, the substantial majority of which was held in a custodial account with another institution, for which SVB Asset Management was the advisor. In March 2023, we amended our Loan and Security Agreement to allow us to hold cash and investments at multiple financial institutions and we began the process of moving cash and investments into accounts at other financial institutions. The Loan and Security Agreement also includes customary representations and warranties, other events of default and termination provisions.

In connection with entering into the Loan and Security Agreement, we issued to the Lenders warrants exercisable for 81,257 shares of our common stock, or the Debt Warrants. The Debt Warrants are exercisable in whole or in part, immediately, and have a per share exercise price of $9.23, which is the closing price of our common stock reported on the Nasdaq Global Market on the day prior to the Effective Date. The Debt Warrants will terminate on the earlier of February 28, 2030 or the closing of certain merger or consolidation transactions.

Leases

In June 2021, we entered into a third amendment, or Third Amendment, to our manufacturing facility lease, dated May 18, 2011, as amended, by and between Alemany Plaza LLC, located at San Carlos, California, or San Carlos Lease, as an extension to the term of the San Carlos Lease for a period of five years, or the Lease Extension Period. Pursuant to the Third Amendment, the San Carlos Lease will expire on July 31, 2026, and it includes an option to renew the San Carlos Lease for an additional five years. The aggregate estimated base rent payments due over the Lease Extension Period is approximately $4.2 million, subject to certain terms contained in the San Carlos Lease.

In June 2021, we entered into a first amendment, or First Amendment, to our manufacturing facility lease, dated May 4, 2015, as amended, by and between 870 Industrial Road LLC, located at San Carlos, California, or the Industrial Lease, as an extension to the term of the Industrial Lease for a period of five years, or the Industrial Lease Extension Period. Pursuant to the first Amendment, the Industrial Lease will expire on June 30, 2026, and it includes an option to renew the Industrial Lease for an additional five years. The aggregate estimated base rent payments due over the Industrial Lease Extension Period is approximately $4.3 million, subject to certain terms contained in the Industrial Lease.

In September 2020, we entered into a sublease agreement, or the Sublease with Five Prime Therapeutics, Inc., or the Sublessor, for approximately 115,466 square feet, in a building located in South San Francisco, California, or the Premises. We use the Premises as our corporate headquarters and to conduct (or expand) research and development activities. We commenced making monthly payments for the first 85,755 square feet of the Premises, or Initial Premises, in July 2021, with occupancy of such space commencing in August 2021. We were provided early access to the Initial Premises in the fourth quarter of 2020 to conduct certain planning and tenant improvement work. The Sublease is subordinate to the lease agreement, effective December 12, 2016, between the Sublessor and HCP Oyster Point III LLC, or the Landlord. The commencement date for the remaining 29,711 square feet of the Premises, or the Expansion Premises, is expected to be 24 months following the commencement date on the Initial Premises. However, we have the right to accelerate the commencement date on the Expansion Premises to an earlier date upon six months’ prior written notice to the Sublessor. The Sublease for both the Initial Premises and Expansion Premises will expire on December 31, 2027. With a commencement date on the Initial Premises of July 1, 2021, the aggregate estimated base rent payments due over the term of the Sublease are approximately $39.1 million, including the approximately $5.2 million in potential financial benefit to us of base rent abatement to be provided by the Sublessor, subject to certain terms contained in the Sublease. The Sublease contains customary provisions requiring us to pay our pro rata share of utilities and a portion of the operating expenses and certain taxes, assessments and fees of the Premises and provisions allowing the Sublessor to terminate the Sublease upon the termination of the lease with the Landlord or if we fail to remedy a breach of certain of its obligations within specified time periods. Additionally, we posted a security deposit of $0.9 million, which is reflected as restricted cash in non-current assets on our balance sheet as of December 31, 2022 and 2021.

Funding Requirements

Based upon our current operating plan, we believe that our existing capital resources will enable us to fund our operating expenses and capital expenditure requirements through at least the next twelve months after the date of this filing. We have based this estimate on assumptions that may prove to be wrong, and we could utilize our available capital resources sooner than we currently expect. We will continue to require additional financing to advance our current product candidates into and through clinical development, to develop, acquire or in-license other potential product candidates, pay our obligations and to fund operations for the foreseeable future.

We may seek to raise any necessary additional capital through a combination of public or private equity offerings, debt financings, collaborations, strategic alliances, licensing arrangements, marketing and distribution arrangements, or other sources of financing. Adequate additional funding may not be available to us on acceptable terms, or at all. Any failure to raise capital as and when needed could have a negative impact on our financial condition and on our ability to pursue our business plans and strategies, and may cause us to delay, reduce the scope of or suspend one or more of our pre-clinical and clinical studies, research and development programs or commercialization efforts, and may necessitate us to delay, reduce or terminate planned activities in order to reduce costs. Due to the numerous risks and uncertainties associated with the development and commercialization of our product candidates and the extent to which we may enter into additional collaborations with third parties to participate in their development and commercialization, we are unable to estimate the amounts of increased capital outlays and operating expenditures associated with our current and anticipated clinical studies.

To the extent we raise additional capital through new collaborations, strategic alliances or licensing arrangements with third parties, we may have to relinquish valuable rights to our product candidates, future revenue streams, research programs or product candidates or to grant licenses on terms that may not be favorable to us. If we do raise additional capital through public or private equity or convertible debt offerings, the ownership interest of our existing stockholders will be diluted, and the terms of these securities may include liquidation or other preferences that adversely affect our stockholders’ rights. If we raise additional capital through debt financing, we may be subject to covenants limiting or restricting our ability to take specific actions, such as incurring additional debt, making capital expenditures or declaring dividends.

Cash Flows

The following table summarizes our cash flows during the periods indicated:

Year Ended December 31,

(in thousands)

Cash provided by (used in) operating activities $ 3,549 $ (81,679 )

Cash used in investing activities (35,022 ) (97,315 )

Cash provided by financing activities 48,313 3,256

Cash Flows from Operating Activities

Cash provided by operating activities for the year ended December 31, 2022 was $3.5 million. Our net loss of $119.2 million included non-cash charges of $26.3 million for stock-based compensation, $12.1 million for the unrealized gain on equity securities as a result of the remeasurement of the estimated fair value of our investment in Vaxcyte common stock, $5.7 million for depreciation and amortization, $4.1 million for the realized gain on equity securities, $2.6 million for noncash lease expenses, $0.4 million for the accretion of discount on our marketable securities and $0.3 million in other non-cash charges. Cash provided by operating activities also reflected a net change in operating assets and liabilities of $104.4 million, due to an increase of $93.6 million in our deferred revenue balance primarily due to the upfront payment from Astellas, a decrease of $5.3 million in accounts receivable from our collaborators, an increase of $5.3 million in accounts payable, accrued expenses and other liabilities due to timing of payments, an increase of $1.7 million in accrued compensation due to increased headcount, and an increase of $1.9 million in our operating lease liability, which were partially offset by an increase of $3.5 million in prepaid expenses and other assets.

Cash used in operating activities for the year ended December 31, 2021 was $81.7 million. Our net loss of $105.5 million included non-cash charges of $23.2 million for stock-based compensation, $4.9million for noncash lease expenses, $4.8 million for depreciation and amortization, $4.5 million of unrealized loss on equity securities as a result of the remeasurement of the estimated fair value of our investment in Vaxcyte common stock, $2.8 million for the amortization of premiums on our marketable securities, and $1.2 million in other non-cash charges. Cash used in operating activities also reflected a net change in operating assets and liabilities of $17.6 million, due to a decrease of $15.2 million in our deferred revenue balance from revenue recognized under our collaboration agreements, an increase of $6.9 million in accounts receivable from our collaborators, an increase of $4.0 million in prepaid expenses and other assets and a decrease of $2.7 million in our operating lease liability, which were partially offset by an increase of $8.6 million in accounts payable, accrued expenses and other liabilities due to timing of payments and an increase of $2.6 million in accrued compensation due to increased headcount.

Cash Flows from Investing Activities

Cash used in investing activities of $35.0 million for the year ended December 31, 2022 was primarily related to purchases of marketable securities of $216.7 million and purchases of property and equipment of $7.9 million, principally for laboratory equipment, partially offset by maturities and sales of marketable securities of $160.8 million and proceeds from sale of Vaxcyte equity securities of $28.7 million.

Cash used in investing activities of $97.3million for the year ended December 31, 2021 was primarily related to purchases of marketable securities of $248.7million and purchases of property and equipment of $15.3million, principally for leasehold improvements to the Premises under the Sublease, partially offset by maturities and sales of marketable securities of $166.7million.

Cash Flows from Financing Activities

Cash provided by financing activities of $48.3 million for the year ended December 31, 2022 was primarily related to $56.3 million of net proceeds from our ATM Facility sales of common stock, $1.6 million of net proceeds received from participants in our employee equity plans and $0.3 million of proceeds received from the exercise of common stock options, partially offset by debt repayment of $9.4 million and a $0.5 million tax payment related to the net share settlement of certain vested restricted stock units.

Cash provided by financing activities of $3.3million for the year ended December 31, 2021 was primarily related to $2.5million of proceeds received from the exercise of common stock options, and $1.8 million of net proceeds received from participants in our employee equity plans, partially offset by a $1.0 million tax payment related to the net share settlement of certain vested restricted stock units.

Contractual Obligations and Other Commitments

In addition to the contractual obligations and commitments as noted above and elsewhere in this Annual Report with regards to the leases and term loans, we enter into agreements in the normal course of business, including with contract research organizations for clinical trials, contract manufacturing organizations for certain manufacturing services, and vendors for preclinical studies and other services and products for operating purposes, which are generally cancelable upon written notice.

Critical Accounting Policies and Estimates

Our management’s discussion and analysis of our financial condition and results of operations is based on our financial statements, which have been prepared in accordance with United States generally accepted accounting principles. The preparation of these financial statements requires us to make estimates and assumptions that affect the reported amounts of assets and liabilities and the disclosure of contingent assets and liabilities at the date of the financial statements, as well as the reported revenue generated and expenses incurred during the reporting periods. Our estimates are based on our historical experience and on various other factors that we believe are reasonable under the circumstances, the results of which form the basis for making judgments about the carrying value of assets and liabilities that are not readily apparent from other sources. Actual results may differ from these estimates under different assumptions or conditions.

While our significant accounting policies are described in the notes to our financial statements included elsewhere in this report, we believe that the following critical accounting policies are most important to understanding and evaluating our reported financial results.

Revenue Recognition

We do not have any products approved for commercial sale and have not generated any revenue from commercial product sales. Our total revenue to date has been generated principally from our collaboration and license agreements with BMS, Merck, Astellas, EMD Serono, Vaxcyte, BioNova, Tasly, and to a lesser extent, from manufacturing, supply and services and materials we provide to our collaborators.

When we enter into collaboration agreements, we assess whether the arrangements fall within the scope of ASC 808, Collaborative Arrangements (ASC 808) based on whether the arrangements involve joint operating activities and whether both parties have active participation in the arrangement and are exposed to significant risks and rewards. To the extent that the arrangement falls within the scope of ASC 808, we assess whether the payments between us and our collaboration partner fall within the scope of other accounting literature. If we conclude that payments from the collaboration partner to us represent consideration from a customer, such as license fees and contract research and development activities, we account for those payments within the scope of ASC 606, Revenue from Contracts with Customers. However, if we conclude that our collaboration partner is not a customer for certain activities and associated payments, such as for certain collaborative research, development, manufacturing and commercial activities, we present such payments as a reduction of research and development expense or general and administrative expense, based on where we present the underlying expense.

Collaboration revenue: We derive revenue from collaboration arrangements, under which we may grant licenses to our collaboration partners to further develop and commercialize our proprietary product candidates.

We may also perform research and development activities under the collaboration agreements. Consideration under these contracts generally includes a nonrefundable upfront payment, development, regulatory and commercial milestones and other contingent payments, and royalties based on net sales of approved products. Additionally, the collaborations may provide options for the customer to acquire from us materials and reagents, clinical product supply or additional research and development services under separate agreements.

We assess which activities in the collaboration agreements are considered distinct performance obligations that should be accounted for separately. We develop assumptions that require judgement to determine whether the license to our intellectual property is distinct from the research and development services or participation in activities under the collaboration agreements.

At the inception of each agreement, we determine the arrangement transaction price, which includes variable consideration, based on the assessment of the probability of achievement of future milestones and contingent payments and other potential consideration. We recognize revenue over time by measuring the progress towards the complete satisfaction of the relevant performance obligation using an appropriate input or output method based on the nature of the service promised to the customer.

For arrangements that include multiple performance obligations, we allocate the transaction price to the identified performance obligations based on the standalone selling price, or SSP, of each distinct performance obligation. In instances where SSP is not directly observable, we develop assumptions that require judgment to determine the SSP for each performance obligation identified in the contract. These key assumptions may include full-time equivalent, or FTE, personnel effort, estimated costs, discount rates and probabilities of clinical development and regulatory success.

Upfront Payments: For collaboration arrangements that include a nonrefundable upfront payment, if the license fee and research and development services cannot be accounted for as separate performance obligations, the transaction price is deferred and recognized as revenue over the expected period of performance using a cost-based input methodology. We use judgement to assess the pattern of delivery of the performance obligation. In addition, amounts paid in advance of services being rendered may result in an associated financing component to the upfront payment. Accordingly, the interest on such borrowing cost component will be recorded as interest expense and revenue, based on an appropriate borrowing rate applied to the value of services to be performed by us over the estimated service performance period.

License Grants: For collaboration arrangements that include a grant of a license to our intellectual property, we consider whether the license grant is distinct from the other performance obligations included in the arrangement. For licenses that are distinct, we recognize revenues from nonrefundable, upfront payments and other consideration allocated to the license when the license term has begun and we have provided all necessary information regarding the underlying intellectual property to the customer, which generally occurs at or near the inception of the arrangement.

Milestone and Contingent Payments: At the inception of the arrangement and at each reporting date thereafter, we assess whether we should include any milestone and contingent payments or other forms of variable consideration in the transaction price using the most likely amount method. If it is probable that a significant reversal of cumulative revenue would not occur upon resolution of the uncertainty, the associated milestone value is included in the transaction price. At the end of each subsequent reporting period, we re-evaluate the probability of achievement of each such milestone and any related constraint and, if necessary, adjust our estimate of the overall transaction price. Since milestone and contingent payments may become payable to us upon the initiation of a clinical study or filing for or receipt of regulatory approval, we review the relevant facts and circumstances to determine when we should update the transaction price, which may occur before the triggering event. When we update the transaction price for milestone and contingent payments, we allocate the changes in the total transaction price to each performance obligation in the agreement on the same basis as the initial allocation. Any such adjustments are recorded on a cumulative catch-up basis in the period of adjustment, which may result in recognizing revenue for previously satisfied performance obligations in such period. Our collaborators generally pay milestones and contingent payments subsequent to achievement of the triggering event.

Research and Development Services: For amounts allocated to our research and development obligations in a collaboration arrangement, we recognize revenue over time using a cost-based input methodology, representing the transfer of goods or services as activities are performed over the term of the agreement.

Materials Supply: We provide materials and reagents, clinical materials and services to certain of our collaborators under separate agreements. The consideration for such services is generally based on FTE personnel effort used to manufacture those materials, reimbursed at an agreed upon rate in addition to agreed-upon pricing for the provided materials. The amounts billed are recognized as revenue as the performance obligations are met by us.

Revenue subject to governmental withholding taxes is recognized on a gross basis with the withholding taxes recorded as a component of income tax expense.

Research and Development

We record accrued expenses for estimated costs of our research and development activities conducted by third party service providers, which include outsourced research and development expenses, professional services and contract manufacturing activities. We record the estimated costs of research and development activities based upon the estimated amount of services provided but not yet invoiced, and include these costs in current liabilities in the Balance Sheets and within research and development expense in the Statements of Operations.

Nonrefundable advance payments for goods or services that will be used or rendered for future research and development activities are deferred and capitalized and recognized as an expense as the goods are delivered or the related services are performed.

For outsourced research and development expenses, such as professional fees payable to third parties for preclinical studies, clinical trials and research services and other consulting costs, we estimate the expenses based on the services performed, pursuant to contracts with research institutions that conduct and manage preclinical studies, clinical trials and research services on our behalf. We estimate these expenses based on discussions with internal management personnel and external service providers as to the progress or stage of completion of services and the contracted fees to be paid for such services. If the actual timing of the performance of services or the level of effort varies from the original estimates, we will adjust the accrual accordingly. Payments made to third parties under these arrangements in advance of the performance of the related services by the third parties are recorded as prepaid expenses until the services are rendered.

Stock-Based Compensation

We measure and recognize compensation expense for all stock-based awards, including restricted stock units, stock options, and the ESPP, to employees, consultants and nonemployee directors based on the estimated fair value of the awards on the grant date. The fair value of stock options and purchase rights under the ESPP are estimated using the Black-Scholes option-pricing model. The Black-Scholes model requires use of assumptions and judgments about the variables used in the calculations, including the expected term, the expected volatility of the underlying stock, the related risk-free interest rate for the expected term of the award and the expected dividends.

Stock-based compensation expense for restricted stock units and stock options is generally recognized on a straight line basis over the requisite service period. Stock-based compensation expense for the ESPP is recognized on a straight-line basis over the offering period. We account for forfeitures of stock-based awards as they occur.

The closing sale price per share of our common stock as reported on the Nasdaq Global Market on the date of grant is used to determine the exercise price per share of our stock-based awards to purchase common stock.

Income Taxes

As of December 31, 2022, we had federal net operating loss, or NOL, carryforwards of $246.4 million and federal general business credits from research and development expenses totaling $32.5 million, as well as state NOL carryforwards of $118.5 million and state research and development credits of $21.3 million. If not utilized, the federal NOL carryforwards will expire at various dates beginning in 2036, and the federal credits will expire at various dates beginning in 2023. The state NOL carryforwards will expire at various dates beginning in 2030, if not utilized. The state research and development tax credits can be carried forward indefinitely.

Utilization of the net operating loss carryforwards may be subject to a substantial annual limitation due to the ownership change limitations provided by the Tax Reform Act of 1986, or the Tax Reform Act, as amended, and similar state provisions. The annual limitation may result in the expiration of NOLs and credits before utilization. We have performed a Section 382 study for the period of June 16, 2003 through December 31, 2021 and concluded that it is more likely than not that we experienced an ownership change on November 20, 2019. This change does not limit our ability to use our existing NOLs within the carryforward period provided by the Internal Revenue Code, subject to availability of taxable income. We may experience ownership changes in the future as a result of equity offerings or other shifts in our stock ownership, some of which are outside our control. If there is a subsequent event or further change in ownership, these losses may be subject to limitations, resulting in their expiration before they can be utilized.

We assess all material positions taken in any income tax return, including all significant uncertain positions, in all tax years that are still subject to assessment or challenge by relevant taxing authorities. Assessing an uncertain tax position begins with the initial determination of the position’s sustainability and is measured at the largest amount of benefit that is greater than fifty percent likely of being realized upon ultimate settlement. As of each balance sheet date, unresolved uncertain tax positions must be reassessed, and we will determine whether (i) the factors underlying the sustainability assertion have changed and (ii) the amount of the recognized tax benefit is still appropriate. The recognition and measurement of tax benefits requires significant judgment. Judgments concerning the recognition and measurement of a tax benefit might change as new information becomes available.

Recent Accounting Pronouncements

See Note 2 to our audited financial statements included elsewhere in this report for more information.

Item 7A. Quantitative and Qualitative Disclosures about Market Risk

We are exposed to market risks in the ordinary course of our business. These risks primarily include interest rate sensitivities. The primary objective of our investment activities is to preserve our capital to fund our operations. We also seek to maximize income from our investments without assuming significant risk. To achieve our objectives, we maintain a portfolio of cash equivalents and investments in a variety of securities of high credit quality.

We had cash, cash equivalents and marketable securities of $302.3million and $229.5 million as of December 31, 2022 and 2021, respectively, which consisted of money market funds, commercial paper, corporate debt securities, asset-backed securities, U.S. government securities, U.S. agency securities and supranational debt securities. Such interest earning instruments carry a degree of interest rate risk; however, historical fluctuations in interest income have not been significant. Additionally, we had equity securities of $32.0 million as of December 31, 2022, consisting solely of common stock of Vaxcyte.

Equity risk is the risk we will incur economic losses due to adverse changes in equity prices. Our potential exposure to changes in equity prices results from our Vaxcyte common stock holdings. Therefore, we are subject to market risk if such holdings materially decrease in value. A hypothetical 10 percent decrease in the market price for our equity investments as of December 31, 2022 would decrease the fair value by $3.2 million. We intend to manage equity price risk going forward by continuously evaluating market conditions.

We do not enter into investments for trading or speculative purposes and have not used any derivative financial instruments to manage our interest rate risk exposure. We have not been exposed nor do we anticipate being exposed to material risks due to changes in interest rates. A hypothetical 10% change in market interest rates would not have a material impact on our financial statements. We do not believe that our cash, cash equivalents or marketable securities have significant risk of default or illiquidity.

As of December 31, 2022 and 2021, we had $16.3 million and $25.1 million, respectively, in debt outstanding, net of debt discount and accretion of final payment. Our debt with Oxford and SVB bears interest at a floating per annum rate equal to the greater of (i) 8.07% or (ii) the sum of (a) the greater of (1) the thirty (30) day U.S. LIBOR rate reported in the Wall Street Journal on the last business day of the month that immediately precedes the month in which the interest will accrue or (2) 1.67%, plus (b) 6.40%. This debt matures on March 1, 2024 and was interest-only through March 1, 2022. Such interest-bearing debt carries a limited degree of interest rate risk. If overall interest rates had increased or decreased by 100 basis points during the periods presented our interest expense would not have been materially affected.

Item 8. Financial Statements and Supplementary Data

SUTRO BIOPHARMA, INC.

ANNUAL REPORT ON FORM 10-K

INDEX TO AUDITED FINANCIAL STATEMENTS

Page

Report of Independent Registered Public Accounting Firm (PCAOB ID 42) 124

Financial Statements

Balance Sheets 126

Statements of Operations 127

Statements of Comprehensive Loss 128

Statements of Stockholders’ Equity 129

Statements of Cash Flows 130

Notes to Financial Statements 131

Report of Independent Registered Public Accounting Firm

To the Stockholders and the Board of Directors of Sutro Biopharma, Inc.

Opinion on the Financial Statements

We have audited the accompanying balance sheets of Sutro Biopharma, Inc. (the Company) as of December 31, 2022 and 2021, the related statements of operations, comprehensive loss, stockholders’ equity and cash flows for each of the three years in the period ended December 31, 2022, and the related notes (collectively referred to as the “financial statements”). In our opinion, the financial statements present fairly, in all material respects, the financial position of the Company as of December 31, 2022 and 2021, and the results of its operations and its cash flows for each of the three years in the period ended December 31, 2022, in conformity with U.S. generally accepted accounting principles.

Basis for Opinion

These financial statements are the responsibility of the Company's management. Our responsibility is to express an opinion on the Company’s financial statements based on our audits. We are a public accounting firm registered with the Public Company Accounting Oversight Board (United States) (PCAOB) and are required to be independent with respect to the Company in accordance with the U.S. federal securities laws and the applicable rules and regulations of the Securities and Exchange Commission and the PCAOB.

We conducted our audits in accordance with the standards of the PCAOB. Those standards require that we plan and perform the audit to obtain reasonable assurance about whether the financial statements are free of material misstatement, whether due to error or fraud. The Company is not required to have, nor were we engaged to perform, an audit of its internal control over financial reporting. As part of our audits we are required to obtain an understanding of internal control over financial reporting but not for the purpose of expressing an opinion on the effectiveness of the Company’s internal control over financial reporting. Accordingly, we express no such opinion.

Our audits included performing procedures to assess the risks of material misstatement of the financial statements, whether due to error or fraud, and performing procedures that respond to those risks. Such procedures included examining, on a test basis, evidence regarding the amounts and disclosures in the financial statements. Our audits also included evaluating the accounting principles used and significant estimates made by management, as well as evaluating the overall presentation of the financial statements. We believe that our audits provide a reasonable basis for our opinion.

Critical Audit Matter

The critical audit matter communicated below is matter arising from the current period audit of the financial statements that was communicated or required to be communicated to the audit committee and that: (1) relates to accounts or disclosures that are material to the financial statements and (2) involved our especially challenging, subjective or complex judgments. The communication of the critical audit matter does not alter in any way our opinion on the financial statements, taken as a whole, and we are not, by communicating the critical audit matter below, providing a separate opinion on the critical audit matter or on the accounts or disclosures to which it relates.

/s/ Ernst & Young LLP

We have served as the Company’s auditor since 2007.

San Mateo, California

March 30, 2023

SUTRO BIOPHARMA, INC.

BALANCE SHEETS

(in thousands, except share and per share data)

December 31,

Assets

Current assets:

Prepaid expenses and other current assets 11,667 8,123

Marketable securities, non-current - 68,775

Liabilities and Stockholders’ Equity

Current liabilities:

Operating lease liability-current 4,585 1,037

Accrued expenses and other current liabilities 14,764 8,402

Deferred revenue, non-current 89,885 -

Operating lease liability-non-current 29,574 31,224

Other non-current liabilities 119 146

Commitments and contingencies (Note 8)

Stockholders’ equity:

Accumulated other comprehensive loss (618 ) (314 )

Total Liabilities and Stockholders’ Equity $ 406,944 $ 341,408

See accompanying notes to financial statements.

SUTRO BIOPHARMA, INC.

STATEMENTS OF OPERATIONS

(in thousands, except share and per share data)

Year Ended December 31,

Operating expenses

Interest and other income (expense), net (3,346 ) (3,137 ) (3,974 )

Provision for income taxes 2,500 - 103

Net loss per share, basic and diluted $ (2.35 ) $ (2.29 ) $ (0.99 )

See accompanying notes to financial statements.

SUTRO BIOPHARMA, INC.

STATEMENTS OF COMPREHENSIVE LOSS

(in thousands)

Year Ended December 31,

Other comprehensive loss:

Net unrealized loss on available-for-sale securities (304 ) (443 ) (36 )

See accompanying notes to financial statements.

SUTRO BIOPHARMA, INC.

Statements of Stockholders’ Equity

(in thousands, except share amounts)

Accumulated

Additional Other Total

Common Stock Paid-In- Comprehensive Accumulated Stockholders’

Shares Amount Capital (Loss) Income Deficit Equity

Vesting of restricted stock units 151,976 - - - - -

Stock-based compensation expense - - 11,917 - - 11,917

Net unrealized loss on available-for-sale securities - - - (36 ) - (36 )

Return and retirement of common stock (7,687 ) - (7 ) - - (7 )

Vesting of restricted stock units 238,724 - - - - -

Stock-based compensation expense - - 23,241 - - 23,241

Net unrealized loss on available-for-sale securities - - - (443 ) - (443 )

Vesting of restricted stock units 620,647 1 (1 ) - - -

Stock-based compensation expense - - 26,304 - - 26,304

Net unrealized loss on available-for-sale securities - - - (304 ) - (304 )

See accompanying notes to financial statements.

SUTRO BIOPHARMA, INC.

STATEMENTS OF CASH FLOWS

(in thousands)

Year Ended December 31,

Operating activities

Realized gain on equity securities (4,074 ) - -

Remeasurement of liability awards (2 ) (12 ) 19

Changes in operating assets and liabilities:

Prepaid expenses and other assets (3,544 ) (3,959 ) (80 )

Deferred rent - - 931

Change in operating lease liability 1,898 (2,727 ) -

Net cash provided by (used in) operating activities 3,549 (81,679 ) (67,802 )

Investing activities

Proceeds from sale of equity securities, net 28,739 - -

Purchases of equipment and leasehold improvements (7,858 ) (15,323 ) (7,129 )

Proceeds from exercise of options for Vaxcyte shares 9 9 89

Net cash (used in) provided by investing activities (35,022 ) (97,315 ) 604

Financing activities

Proceeds from sales of common stock, net of issuance costs 56,270 - 251,415

Proceeds from debt refinancing - - 25,000

Proceeds from exercise of common stock options 268 2,485 1,861

Return and retirement of common stock - (7 ) -

Supplemental disclosure of cash flow information

Income tax paid $ - $ 103 $ -

Supplemental Disclosures of Non-cash Investing and Financing Information

Offering costs included in accounts payable $ - $ - $ 361

Financing component associated with program fees $ 5,079 $ 610 $ 1,852

Warrants issued to lenders $ - $ - $ 619

See accompanying notes to financial statements.

SUTRO BIOPHARMA, Inc.

Notes to Financial Statements

1. Organization and Principal Activities

Description of Business

Sutro Biopharma, Inc. (the “Company”), is a clinical-stage oncology company developing site-specific and novel-format antibody drug conjugates, or ADCs. The Company was incorporated on April 21, 2003 and is headquartered in South San Francisco, California.

The Company operates in one business segment, the development of biopharmaceutical products.

At-The-Market Sales

During the year ended December 31, 2022, the Company sold an aggregate of 10,285,160shares of its common stock through its At-the-Market Facility (“ATM Facility”) pursuant to its Open Market Sales AgreementSM dated April 2, 2021 with Jefferies LLC (“Jefferies”), as sales agent (the “Sales Agreement”).

During the year ended December 31, 2022, the gross proceeds from these sales were approximately $58.3 million, before deducting fees of approximately $2.0 million, resulting in net proceeds of approximately $56.3 million, to the Company.

Liquidity

The Company has incurred significant losses to date and had negative cash flows from operations in the years prior to the year ended December 31, 2022. As of December 31, 2022, there was an accumulated deficit of $452.6 million. Management expects to continue to incur additional substantial losses in the foreseeable future as a result of the Company’s research and development and other operational activities.

As of December 31, 2022, the Company had unrestricted cash, cash equivalents and marketable securities of $302.3 million and equity securities of $32.0 million, consisting solely of common stock of Vaxcyte, which are available to fund future operations. The Company will need to raise additional capital to support the completion of its research and development activities and to support its operations.

The Company believes that its unrestricted cash, cash equivalents, marketable securities and equity securities as of December 31, 2022 will enable the Company to maintain its operations for a period of at least 12 months following the filing date of these financial statements.

2. Basis of Presentation and Summary of Significant Accounting Policies

Basis of Presentation and Use of Estimates

The accompanying financial statements have been prepared in accordance with U.S. generally accepted accounting principles (“U.S. GAAP”). The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. The Company bases its estimates on historical experience and market-specific or other relevant assumptions that it believes are reasonable under the circumstances. The amounts of assets and liabilities reported in the Company’s Balance Sheets and the amounts of expenses and income reported for each of the periods presented are affected by estimates and assumptions, which are used for, but are not limited to, determining research and development periods under collaboration arrangements, stock-based compensation expense, valuation of marketable securities, impairment of long-lived assets, income taxes and certain accrued liabilities. Actual results could differ from such estimates or assumptions.

Recent Accounting Pronouncements Not Yet Adopted

There were no new accounting pronouncements issued since our filing of the Annual Report on Form 10-K for the year ended December 31, 2021, which would have a significant effect on our financial statements.

Prior Period Reclassifications

The prior period presentation of interest and other income (expense), net and provision for income taxes have been updated to conform to current period presentation. The reclassifications had no effect on prior years' net loss.

The prior period presentation of accounts payable and accrued expenses and other current liabilities have been updated to conform to current period presentation. Accordingly, adjustments have been made to the Balance Sheets and Statements of Cash Flows. The reclassifications had no effect on prior years' net loss.

Cash, Cash Equivalents, Marketable Securities and Restricted Cash

The Company considers all highly liquid investments with original maturities of 90 days or less from the date of purchase to be cash equivalents. Investments with original maturities of greater than 90 days from the date of purchase but less than one year from the balance sheet date, or where the Company's intent is to use the investments to fund current operations or to make them available for current operations are classified as current, while investments with maturities in one year or beyond one year from the balance sheet date are classified as long-term investments.

Available-for-sale marketable securities are carried at fair value, with unrealized gains and losses reported as a component of accumulated other comprehensive income (loss). Realized gains and losses are included in interest income in the Company’s Statements of Operations. There were no material realized gains or losses in the periods presented. The cost of securities sold is based on the specific-identification method.

The Company evaluates, on a quarterly basis, its marketable securities for potential impairment. For marketable securities in an unrealized loss position, the Company assesses whether such declines are due to credit loss based on factors such as changes to the rating of the security by a ratings agency, market conditions and supportable forecasts of economic and market conditions, among others. If a credit loss exists, the Company assesses whether it has plans to sell the security or it is more likely than not it will be required to sell any marketable security before recovery of its amortized cost basis. If either condition is met, the security’s amortized cost basis is written down to fair value and is recognized through interest and other income (expense), net.

If neither condition is met, declines as a result of credit losses, if any, are recognized as an allowance for credit loss, limited to the amount of unrealized loss, through interest and other income (expense), net. Any portion of unrealized loss that is not a result of a credit loss, is recognized in other comprehensive income (loss).

The Company invests in money market funds, commercial paper, corporate debt securities, asset-based securities, U.S. government securities, U.S. agency securities and supranational debt securities with high credit ratings. The Company has established guidelines regarding diversification of its investments and their maturities, with the objectives of maintaining safety and liquidity while maximizing yield.

Under certain agreements, the Company has pledged cash and cash equivalents as collateral. As of December 31, 2022 and 2021, restricted cash related to such agreements was $0.9 million and $0.9 million, respectively.

A reconciliation of cash, cash equivalents, and restricted cash reported within the Company’s Balance Sheets to the amount reported within the accompanying Statements of Cash Flows was as follows:

December 31,

(in thousands)

Concentrations of Credit Risk

Cash and cash equivalents and marketable securities consist of financial instruments that potentially subject the Company to a concentration of credit risk, to the extent of the amounts recorded on the Balance Sheets. The Company minimizes the amount of credit exposure by investing cash that is not required for immediate operating needs in money market funds, government obligations and/or commercial paper with short maturities.

The Company performs a regular review of its collaborators’ credit risk and payment histories when circumstances warrant, including payments made subsequent to year-end. When appropriate, the Company provides for an allowance for credit risks by reserving for specifically identified doubtful accounts, although historically the Company has not experienced credit losses from its accounts receivable.

Investments in Equity Securities

Vaxcyte common stock held by the Company is measured at fair value at each reporting period based on the closing price of Vaxcyte’s common stock on the last trading day of each reporting period, with any realized or unrealized gains and losses recorded in the Company’s Statements of Operations.

Property and Equipment, Net

Property and equipment are stated at cost, less accumulated depreciation and amortization. Depreciation is determined using the straight-line method over the estimated useful lives of the respective assets, generally three to five years. Leasehold improvements are amortized on a straight-line basis over the shorter of their estimated useful lives or the term of the lease. Maintenance and repairs are charged to expense as incurred and costs of improvement are capitalized.

Impairment of Long-Lived Assets

The Company reviews long-lived assets, including property and equipment, leasehold improvements and right-of-use assets for impairment whenever events or changes in business circumstances indicate that the carrying amount of the assets may not be fully recoverable. An impairment loss would be recognized when the estimated, undiscounted future cash flows expected to result from the use of the asset and its eventual disposition are less than its carrying amount. Impairment, if any, is measured at the amount by which the carrying amount of a long-lived asset exceeds its fair value.

The Company did not recognize any impairment charges during the years ended December 31, 2022, 2021 and 2020. As of December 31, 2022 and 2021, management believes that no revision to the remaining useful lives or write down of the remaining long-lived assets is required.

Leases

The Company adoptedASU 2016-02 (Topic 842), Leases (Accounting Standards Codification, or “ASC”, 842) on July 1, 2021, effective as of January 1, 2021. The Company determines if an arrangement is or contains a lease at contract inception by assessing whether the arrangement contains an identified asset and whether the lessee has the right to control such asset. The Company is required to classify leases as either finance or operating leases and to record a ROU asset and a lease liability for all leases with a term greater than 12 months regardless of the lease classification. The lease classification will determine whether the lease expense is recognized based on an effective interest rate method or on a straight-line basis over the term of the lease. The Company determines the initial classification and measurement of its ROU assets and lease liabilities at the lease commencement date and thereafter, if modified. The Company does not have material finance leases.

For leases with a term greater than 12 months, the Company records the related ROU asset and lease liability at the present value of lease payments over the term of the lease. The term of the Company’s leases equals the non-cancellable period of the lease, including any rent-free periods provided by the lessor, and also includes options to extend or terminate the lease that the Company is reasonably certain to exercise. The ROU asset equals the carrying amount of the related lease liability, adjusted for any lease payments made prior to lease commencement and lease incentives provided by the lessor. Variable lease payments are expensed as incurred and do not factor into the measurement of the applicable ROU asset or lease liability.

The Company has elected, for all classes of underlying assets, not to recognize ROU assets and lease liabilities for leases with a term of 12 months or less. Lease cost for short-term leases is recognized on a straight-line basis over the lease term. The Company has also elected to not separate lease and non-lease components for its leases and, as a result, accounts for lease and non-lease components as one component.

The Company’s leases do not provide a readily determinable implicit rate. Therefore, the Company estimates its incremental borrowing rate to discount the lease payments based on information available at lease commencement. The Company determines its incremental borrowing rate based on the rate of interest that the Company would have to pay to borrow, on a collateralized basis over a similar term, an amount equal to the lease payments in a similar economic environment.

Lease payments may be fixed or variable; however, only fixed payments are included in the Company’s lease liability calculation. Lease costs for the Company’s operating leases are recognized on a straight-line basis within operating expenses over the lease term. The Company’s lease agreements may contain variable non-lease components such as common area maintenance, operating expenses or other costs, which are expensed as incurred.

Revenue Recognition

When the Company enters into collaboration agreements, it assesses whether the arrangements fall within the scope of ASC 808, Collaborative Arrangements ("ASC 808") based on whether the arrangements involve joint operating activities and whether both parties have active participation in the arrangement and are exposed to significant risks and rewards. To the extent that the arrangement falls within the scope of ASC 808, the Company assesses whether the payments between the Company and its collaboration partner fall within the scope of other accounting literature. If it concludes that payments from the collaboration partner to the Company represent consideration from a customer, such as license fees and contract research and development activities, the

Company accounts for those payments within the scope of Accounting Standards Update (ASU) No. 2014-09 (Topic 606), Revenue from Contracts with Customers (“ASC 606”).

Under ASC 606, an entity recognizes revenue when its customer obtains control of promised goods or services, in an amount that reflects the consideration that the entity expects to receive in exchange for those goods or services. To determine revenue recognition for arrangements that an entity determines are within the scope of ASC 606, the entity performs the following five steps: (i) identify the contract(s) with a customer; (ii) identify the performance obligations in the contract; (iii) determine the transaction price; (iv) allocate the transaction price to the performance obligations in the contract; and (v) recognize revenue when (or as) the Company satisfies a performance obligation. However, if the Company concludes that its collaboration partner is not a customer for certain activities and associated payments, such as for certain collaborative research, development, manufacturing and commercial activities, the Company presents such payments as a reduction of research and development expense or general and administrative expense, based on where the Company presents the underlying expense.

The Company has no products approved for commercial sale and has not generated any revenue from commercial product sales. The total revenue to date has been generated principally from collaboration and license agreements and to a lesser extent, from manufacturing, supply and services and materials the Company provides to its collaboration partners.

Collaboration Revenue: The Company derives revenue from collaboration arrangements, under which the Company may grant licenses to its collaboration partners to further develop and commercialize its proprietary product candidates. The Company may also perform research and development activities under the collaboration agreements. Consideration under these contracts generally includes a nonrefundable upfront payment, development, regulatory and commercial milestones and other contingent payments, and royalties based on net sales of approved products. Additionally, the collaborations may provide options for the customer to acquire from the Company materials and reagents, clinical product supply or additional research and development services under separate agreements.

The Company assesses which activities in the collaboration agreements are considered distinct performance obligations that should be accounted for separately. The Company develops assumptions that require judgement to determine whether the license to the Company’s intellectual property is distinct from the research and development services or participation in activities under the collaboration agreements.

At the inception of each agreement, the Company determines the arrangement transaction price, which includes variable consideration, based on the assessment of the probability of achievement of future milestones and contingent payments and other potential consideration. The Company recognizes revenue over time by measuring its progress towards the complete satisfaction of the relevant performance obligation using an appropriate input or output method based on the nature of the service promised to the customer.

For arrangements that include multiple performance obligations, the Company allocates the transaction price to the identified performance obligations based on the standalone selling price, or SSP, of each distinct performance obligation. In instances where SSP is not directly observable, the Company develops assumptions that require judgment to determine the SSP for each performance obligation identified in the contract. These key assumptions may include full-time equivalent, or FTE, personnel effort, estimated costs, discount rates and probabilities of clinical development and regulatory success.

Upfront Payments: For collaboration arrangements that include a nonrefundable upfront payment, if the license fee and research and development services cannot be accounted for as separate performance obligations, the transaction price is deferred and recognized as revenue over the expected period of performance using a cost-based input methodology. The Company uses judgement to assess the pattern of delivery of the performance obligation. In addition, amounts paid in advance of services being rendered may result in an associated financing component to the upfront payment. Accordingly, the interest on such borrowing cost component will be recorded as interest expense and revenue, based on an appropriate borrowing rate applied to the value of services to be performed by the Company over the estimated service performance period.

License Grants: For collaboration arrangements that include a grant of a license to the Company’s intellectual property, the Company considers whether the license grant is distinct from the other performance obligations

included in the arrangement. For licenses that are distinct, the Company recognizes revenues from nonrefundable, upfront payments and other consideration allocated to the license when the license term has begun and the Company has provided all necessary information regarding the underlying intellectual property to the customer, which generally occurs at or near the inception of the arrangement.

Milestone and Contingent Payments: At the inception of the arrangement and at each reporting date thereafter, the Company assesses whether it should include any milestone and contingent payments or other forms of variable consideration in the transaction price using the most likely amount method. If it is probable that a significant reversal of cumulative revenue would not occur upon resolution of the uncertainty, the associated milestone value is included in the transaction price. At the end of each subsequent reporting period, the Company re-evaluates the probability of achievement of each milestone and any related constraint and, if necessary, adjusts its estimate of the overall transaction price. Since milestone and contingent payments may become payable to the Company upon the initiation of a clinical study or filing for or receipt of regulatory approval, the Company reviews the relevant facts and circumstances to determine when the Company should update the transaction price, which may occur before the triggering event. When the Company updates the transaction price for milestone and contingent payments, the Company allocates the changes in the total transaction price to each performance obligation in the agreement on the same basis as the initial allocation. Any such adjustments are recorded on a cumulative catch-up basis in the period of adjustment, which may result in recognizing revenue for previously satisfied performance obligations in such period. The Company’s collaborators generally pay milestones and contingent payments subsequent to achievement of the triggering event.

Research and Development Services: For amounts allocated to the Company’s research and development obligations in a collaboration arrangement, the Company recognizes revenue over time using a cost-based input methodology, representing the transfer of goods or services as activities are performed over the term of the agreement.

Materials Supply: The Company provides materials and reagents, clinical materials and services to certain of its collaborators under separate agreements. The consideration for such services is generally based on FTE personnel effort used to manufacture those materials reimbursed at an agreed upon rate in addition to agreed-upon pricing for the provided materials. The amounts billed are recognized as revenue as the performance obligations are met by the Company.

Revenue subject to governmental withholding taxes is recognized on a gross basis with the withholding taxes recorded as a component of income tax expense.

Research and Development

The Company records accrued expenses for estimated costs of the research and development activities conducted by third party service providers, which include outsourced research and development expenses, professional services and contract manufacturing activities. The Company records the estimated costs of research and development activities based upon the estimated amount of services provided but not yet invoiced, and includes these costs in current liabilities in the Balance Sheets and within research and development expense in the Statements of Operations.

Nonrefundable advance payments for goods or services that will be used or rendered for future research and development activities are deferred and capitalized and recognized as an expense as the goods are delivered or the related services are performed.

For outsourced research and development expenses, such as professional fees payable to third parties for preclinical studies, clinical trials and research services and other consulting costs, the Company estimates the expenses based on the services performed, pursuant to contracts with research institutions that conduct and manage preclinical studies, clinical trials and research services on the Company’s behalf. The Company estimates these expenses based on discussions with internal management personnel and external service providers as to the progress or stage of completion of services and the contracted fees to be paid for such services. If the actual timing of the performance of services or the level of effort varies from the original estimates, the Company will adjust the accrual accordingly. Payments made to third parties under these arrangements in advance of the performance of the related services by the third parties are recorded as prepaid expenses until the services are rendered.

Stock-Based Compensation

The Company maintains a stock-based compensation plan as a long-term incentive for employees, consultants, and members of the Company’s Board of Directors. The plan allows for the issuance of restricted stock units, non-statutory and incentive stock options to employees and non-statutory stock options to nonemployees. The Company also maintains an employee stock purchase plan.

The Company measures and recognizes compensation expense for all stock-based awards, including restricted stock units, stock options, and the ESPP, to employees, consultants and nonemployee directors based on the estimated fair value of the awards on the grant date. The fair value of stock options and purchase rights under the ESPP are estimated using the Black-Scholes option-pricing model. The Black-Scholes model requires the Company to make assumptions and judgments about the variables used in the calculations, including the expected term, the expected volatility of the underlying stock over the expected term of the award, the related risk-free interest rate for the expected term of the award and the expected dividends.

Stock-based compensation expense for restricted stock units and stock options is generally recognized on a straight line basis over the requisite service period. Stock-based compensation expense for the ESPP is recognized on a straight-line basis over the offering period. The Company accounts for forfeitures of stock-based awards as they occur.

The closing sale price per share of our common stock as reported on the Nasdaq Global Market on the date of grant is used to determine the exercise price per share of our stock-based awards to purchase common stock.

Income Taxes

The Company provides for income taxes under the asset and liability method. Current income tax expense or benefit represents the amount of income taxes expected to be payable or refundable for the current year. Deferred income tax assets and liabilities are determined based on differences between the financial statement reporting and tax bases of assets and liabilities and net operating loss and credit carryforwards, and are measured using the enacted tax rates and laws that will be in effect when such items are expected to reverse. Deferred income tax assets are reduced, as necessary, by a valuation allowance when management determines it is more likely than not that some or all of the tax benefits will not be realized.

The Company accounts for uncertain tax positions in accordance with Accounting Standards Codification (“ASC”) 740-10, Accounting for Uncertainty in Income Taxes. The Company assesses all material positions taken in any income tax return, including all significant uncertain positions, in all tax years that are still subject to assessment or challenge by relevant taxing authorities. Assessing an uncertain tax position begins with the initial determination of the position’s sustainability and is measured at the largest amount of benefit that is greater than fifty percent likely of being realized upon ultimate settlement. As of each balance sheet date, unresolved uncertain tax positions must be reassessed, and the Company will determine whether (i) the factors underlying the sustainability assertion have changed and (ii) the amount of the recognized tax benefit is still appropriate. The recognition and measurement of tax benefits requires significant judgment. Judgments concerning the recognition and measurement of a tax benefit might change as new information becomes available.

The Company includes any penalties and interest expense related to income taxes as a component of interest and other income (expense), net, as necessary.

Fair Value Measurements

Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability, or an exit price, in the principal or most advantageous market for that asset or liability in an orderly transaction between market participants on the measurement date, and establishes a fair value hierarchy that requires an entity to maximize the use of observable inputs, where available, and minimize the use of unobservable inputs when measuring fair value. The Company determined the fair value of financial assets and liabilities using the fair value hierarchy that describes three levels of inputs that may be used to measure fair value, as follows:

Level 1—Quoted prices in active markets for identical assets and liabilities;

Level 2—Inputs other than Level 1 that are observable, either directly or indirectly, such as quoted prices for similar assets or liabilities, quoted prices in markets that are not active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities; and

Level 3—Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities.

The carrying amounts of accounts receivable, prepaid expenses, accounts payable, accrued liabilities and accrued compensation and benefits approximate fair value due to the short-term nature of these items.

The fair value of the Company’s outstanding loan(See Note 7) is estimated using the net present value of the payments, discounted at an interest rate that is consistent with market interest rate, which is a Level 2 input. The estimated fair value of the Company’s outstanding loan approximates the carrying amount, as the loan bears a floating rate that approximates the market interest rate.

Net Loss Per Share

Basic net loss per share is calculated by dividing the net loss by the weighted-average number of shares of common stock outstanding for the period, without consideration for potential dilutive common shares. Basic net loss per share is the same as diluted net loss per share as the inclusion of all potentially dilutive securities would have been anti-dilutive given the net loss of the Company.

3. Fair Value Measurements

The following table sets forth the fair value of the Company’s financial assets and liabilities measured on a recurring basis by level within the fair value hierarchy:

Total Level 1 Level 2 Level 3

(in thousands)

Assets:

Total Level 1 Level 2 Level 3

(in thousands)

Assets:

Where applicable, the Company uses quoted market prices in active markets for identical assets to determine fair value. This pricing methodology applies to Level 1 investments, which are comprised of money market funds, U.S. government securities and the shares of Vaxcyte common stock held by the Company.

If quoted prices in active markets for identical assets are not available, then the Company uses quoted prices for similar assets or inputs other than quoted prices that are observable, either directly or indirectly. These investments are included in Level 2 and consist of commercial paper, corporate debt securities, asset-backed securities, U.S. agency securities and supranational debt securities. These assets are valued using market prices when available, adjusting for accretion of the purchase price to face value at maturity.

A financial instrument’s categorization within the valuation hierarchy is based upon the lowest level of input that is significant to the fair value measurement. The Company’s assessment of the significance of a particular input to the fair value measurement in its entirety requires management to make judgments and consider factors specific to the asset or liability.

In certain cases where there is limited activity or less transparency around inputs to valuation, securities are classified as Level 3 within the valuation hierarchy. As of December 31, 2022 and 2021, the Company did not hold any securities that were classified as Level 3 within the valuation hierarchy.

Investments in Equity Securities

As of December 31, 2022 and 2021, the Company held 667,780and 1,562,879 shares, respectively, of Vaxcyte common stock with an estimated fair value of $32.0 million and $37.2 million, respectively. The Company recognized an unrealized gain (loss) of $12.1 million, $(4.5) million and $41.5 million for the years ended December 31, 2022, 2021 and 2020, respectively.

The Company sold 1,058,434 shares and zero shares of Vaxcyte common stock at their fair market value during the years ended December 31, 2022 and 2021, respectively. The Company recognized a gain of $4.1 million on equity securities during the year ended December 31, 2022 which is recorded under interest and other income (expense), net, in the Statements of Operations.

During the year ended December 31, 2022, the Company received 167,780 shares of Vaxcyte common stock pursuant to a letter agreement (the “ Vaxcyte Agreement”) with Vaxcyte, as a non-cash consideration with a fair value of $7.5 million at the date of the transaction. Please refer to note 5 for additional information.

4. Cash Equivalents and Marketable Securities

Cash equivalents and marketable securities consisted of the following:

AmortizedCost Basis UnrealizedGains UnrealizedLosses FairValue

(in thousands)

Less: amounts classified as cash equivalents (43,318 ) (2 ) - (43,320 )

AmortizedCost Basis UnrealizedGains UnrealizedLosses FairValue

(in thousands)

Less: amounts classified as cash equivalents (29,451 ) - - (29,451 )

As of December 31, 2022 and 2021, zero and $68.8 million, respectively, of marketable securities had maturities of more than one year and are classified as long-term assets.

There were $139.5 million and $176.5 million of investments in an unrealized loss position of $0.6 million and $0.3 million as of December 31, 2022 and 2021, respectively. During the years ended December 31, 2022, 2021 and 2020, the Company did not record any other-than-temporary impairment charges on its available-for-sale securities. Based on the Company’s procedures under the expected credit loss model, including an assessment of unrealized gains and losses on the portfolio after December 31, 2022, the Company concluded that the unrealized losses for its marketable securities were not attributable to credit and therefore an allowance for credit losses for these securities has not been recorded as of December 31, 2022. Also, based on the scheduled maturities of the investments, the Company was more likely than not to hold these investments for a period of time sufficient for a recovery of the Company’s cost basis.

The Company recognized no material gains or losses on its cash equivalents and current and non-current marketable securities as of December 31, 2022 and as a result, the Company did not reclassify any amounts out of accumulated other comprehensive income (loss) for the year then ended.

5. Collaboration and License Agreements and Supply Agreements

The Company has entered into collaboration and license agreements and supply agreements with various pharmaceutical and biotechnology companies. The Company analyzes its agreements to determine whether it should account for the agreements within the scope of ASC 808, and, if so, it analyzes whether it should account for any elements under ASC 606.

The Company’s accounts receivable balances may contain billed and unbilled amounts from upfront payments, milestones and other contingent payments, as well as reimbursable costs from collaboration and license agreements and supply agreements. The Company has not experienced credit losses from its accounts receivable and, therefore, has not recorded a reserve for estimated credit losses as of December 31, 2022 and 2021.

In accordance with its agreements, the Company recognized revenue as follows:

Year Ended December 31,

(in thousands)

Astellas Pharma Inc. (“Astellas”) 10,897 - -

BioNova Pharmaceuticals, Ltd. (“BioNova”) 4,000 - -

Tasly Biopharmaceuticals Co., Ltd. (“Tasly”) 25,000 - -

(1)

Merck was a related party until the closing of the Company's public offering on May 14, 2020.

(2)

Vaxcyte was a related party until the closing of its initial public offering on June 16, 2020.

The following table presents the changes in the Company’s deferred revenue balance from its agreements during the year ended December 31, 2022:

Year ended

(in thousands)

Additions to deferred revenue 113,717

Recognition of revenue in current period (12,569 )

The Company’s balance of deferred revenue contains upfront payments and an advance payment for an obligation from one of our supply agreements which remains partially unsatisfied. The Company expects to recognize approximately$16.8 million of the deferred revenue over the next twelve months.

There have been no material changes to the Company’s agreements during the year ended December 31, 2022, except as described below.

Collaboration with BMS

BMS Agreement

In September 2014, the Company signed a Collaboration and License Agreement (the “BMS Agreement”) with BMS to discover and develop bispecific antibodies and/or antibody-drug conjugates (“ADCs”), focused primarily on the field of immuno-oncology, using the Company’s proprietary integrated cell-free protein synthesis platform, XpressCF®. In August 2017, the Company entered into an amended and restated collaboration and license agreement with BMS to refocus the collaboration on four programs that were advancing through preclinical development, including an ADC program targeting B cell maturation antigen (“BCMA ADC”).

In May 2019, the U.S. Food and Drug Administration cleared the investigational new drug (“IND”) application for the BCMA ADC, which was discovered and manufactured by the Company and is the first collaboration program IND. BMS has worldwide development and commercialization rights with respect to the BCMA ADC. The Company will continue to be responsible for clinical supply manufacturing and certain development services for the BCMA ADC and is eligible to receive from BMS aggregate development and regulatory contingent payments of up to $275.0 million, if approved in multiple indications, and tiered royalties ranging from mid to high single digit percentages on worldwide sales of any resulting commercial products.

As of December 31, 2022 and 2021, there was no balance of deferred revenue related to payments received by the Company under the BMS Agreement.

2018 BMS Master Services Agreement

In March 2018, the Company entered into a Master Development and Clinical Manufacturing Services Agreement (the “2018 BMS Master Services Agreement”) with BMS, wherein BMS requested the Company to provide development, manufacturing and supply chain management services, including clinical product supply.

As of December 31, 2022 and 2021, there was $3.1 million and $0.6 million, respectively, of deferred revenue under the 2018 BMS Master Services Agreement.

Revenues under the BMS Agreement and the 2018 BMS Master Services Agreement were as follows:

Year ended December 31,

(in thousands)

Collaboration with Merck

2018 Merck Agreement

In July 2018, the Company entered into an agreement (the “2018 Merck Agreement”) with Merck for access to the Company’s technology and the identification and preclinical research and development of two target programs, with an option for Merck to engage the Company to continue these activities for a third program, upon the payment of an additional amount, focusing on cytokine derivatives for cancer and autoimmune disorders, with an initial transaction price of $60.0 million. The option to expand activities to a third program expired in January 2021.

Under ASC 606, the Company determined there was a financing component associated with the $60.0 million upfront payment on the unearned revenue portion beyond one year from the effective date of the agreement, which amount was recognized as interest expense and revenue over the estimated service period for the first and second target programs.

In March 2020, Merck exercised its option to extend the research term of the collaboration’s first cytokine-derivative program by one year, which, pursuant to the terms of the 2018 Merck Agreement, triggered a payment of $5.0 million. The $5.0 million was, in prior periods, considered to be a fully constrained variable consideration. Removal of the constraint on this variable consideration resulted in a change to the total transaction price, from $60.0 million to $65.0 million. The Company allocated the updated transaction price to all identified performance obligations on the same basis as the initial allocation upon inception of the 2018 Merck Agreement, with any adjustments recorded as a cumulative catch-up in the current period.

In the second quarter of 2021, the Company earned a $15.0 million contingent payment for the initiation by Merck of the first IND-enabling toxicology study under the first cytokine-derivative program in the collaboration. The $15.0 million was, in prior periods, considered to be a fully constrained variable consideration. Removal of the constraint on this variable consideration resulted in a change to the total transaction price, from $65.0 million to $80.0 million. The Company allocated the updated transaction price to all identified performance obligations on the same basis as the initial allocation upon inception of the 2018 Merck Agreement, with any adjustments recorded as a cumulative catch-up in the period ended December 31, 2021. As a result of the change in transaction price, the Company recognized substantially all of the $15.0 million contingent payment as a cumulative catch-up in revenue in the period ended December 31, 2021, with a remaining $0.3 million related to the Joint Steering Committee, ("JSC") performance obligation. This remaining $0.3 million related to the JSC performance obligation was recognized during the year ended December 31, 2022.

In September 2021, the Company entered into an amendment to the 2018 Merck Agreement (the “2021 Amendment”) to extend the research term for the first program in the 2018 Merck Agreement to discover and develop novel cytokine derivative therapeutics for cancer and autoimmune disorders. Under the terms of the 2021 Amendment, the Company received a payment of $2.5 million with an additional $7.5 million to be received upon the achievement of certain developmental milestones by Merck on a second molecule under the first cytokine-derivative program of the collaboration. Pursuant to ASC 606, the Company concluded that the 2021 Amendment constitutes a contract modification which is to be accounted for as a separate contract from the 2018 Merck Agreement. From the $2.5 million payment received, $1.9 million was recognized as revenue on a proportion of performance basis in the year ended December 31, 2021, related to the Company’s identified performance obligations under the 2021 Amendment. The remaining $0.6 million was recognized as revenue during the year ended December 31, 2022. Merck decided not to pursue further development of a second molecule under the first cytokine-derivative program of the collaboration and therefore allowed the option to extend the period for nomination of additional clinical candidates under the 2021 Amendment to expire in June 2022.

In December 2021, Merck did not extend the research term for the second research program of the collaboration, which research program reverted to the Company. The first research program of the collaboration is focused on one distinct cytokine derivative molecule for the treatment of cancer. The Company is eligible to receive aggregate contingent payments of up to approximately $0.5 billion for the target program selected by Merck, assuming the development and sale of the therapeutic candidate and all possible indications identified under the collaboration. If one or more products from the target program is developed for non-oncology or a single indication, the Company will be eligible for reduced aggregate contingent payments. In addition, the Company is eligible to receive tiered royalties ranging from mid-single digit to low teen percentages on the worldwide sales of any commercial products that may result from the collaboration.

In July 2022, the first patient was dosed in a Phase 1 study of an investigational candidate resulting from the 2018 Merck Agreement for the development of a novel cytokine derivative therapeutic for the treatment of cancer. As a result of this achievement, the Company earned and received a $10.0 million contingent payment from Merck and recognized the revenue during the year ended December 31, 2022.

As of December 31, 2022 and 2021, there was zero and $0.9 million, respectively, of deferred revenue related to the 2018 Merck Agreement and 2021 Amendment.

2020 Merck Master Services Agreement

In August 2020, the Company entered into a Pre-Clinical and Clinical Supply Agreement (the “2020 Merck Master Services Agreement”) with Merck, wherein Merck requested the Company to provide development, manufacturing and supply chain management services, including clinical product supply, upon completion of the research programs under the 2018 Merck Agreement.

As of both December 31, 2022 and 2021, there was no deferred revenue under the 2020 Merck Master Services Agreement.

Revenues under the 2018 Merck Agreement and the 2020 Merck Master Services Agreement were as follows:

Year ended December 31,

(in thousands)

Contingent payment earned 10,000 - -

Financing component on unearned revenue - 610 1,852

Collaboration with EMD Serono

EMD Serono Agreements

The Company signed a Collaboration Agreement and a License Agreement with EMD Serono in May 2014 and September 2014, respectively, which were entered into in contemplation of each other and therefore treated as a single agreement for accounting purposes. The Collaboration Agreement was subsumed into the License Agreement (the “MDA Agreement”), which agreement is to develop ADCs for multiple cancer targets. Recently, EMD Serono decided to close the Phase 1a trial of M1231 in patients with solid tumors and not initiate a previously planned expansion study. EMD Serono stated that the decision was based on strategic portfolio considerations.

The Company is eligible to receive up to $52.5 million for M1231 under the MDA Agreement, primarily from pre-commercial contingent payments. Relatedly, the Company earned a $2.0 million contingent payment in the second quarter of 2021 related to a patient enrollment achievement in the Phase 1 dose escalation portion of a study of M1231. In August 2020, the Company earned a $1.0 million clinical supply milestone payment under the MDA Agreement. In September 2019, the Company earned a $1.5 million contingent payment under the MDA Agreement upon designation by EMD Serono of a specific bispecific antibody drug conjugate as a clinical development candidate with their approval to advance it to IND-enabling studies. In addition, the Company is eligible to receive tiered royalties ranging from low-to-mid single digit percentages, along with certain additional one-time royalties, on worldwide sales of any commercial products that may result from the MDA Agreement.

As of both December 31, 2022 and 2021, there was no deferred revenue related to payments received by the Company under the MDA Agreement.

2019 EMD Serono Supply Agreement

In April 2019, the Company entered into an ADC Product Preclinical and Phase I Clinical Supply Agreement (the “2019 EMD Serono Supply Agreement”) with EMD Serono, wherein EMD Serono requested the Company to provide development, manufacturing and supply chain management services, including clinical product supply.

As of December 31, 2022 and 2021, there was no deferred revenue related to payments received by the Company under the 2019 EMD Serono Supply Agreement.

Revenues under the EMD Serono agreements were as follows:

Year ended December 31,

(in thousands)

Contingent payment earned $ - $ 2,000 $ 1,000

Astellas License and Collaboration Agreement

In June 2022, the Company entered into a License and Collaboration Agreement (the “Astellas Agreement”) with Astellas for the development of immunostimulatory antibody-drug conjugates for up to three biological targets, to be identified by Astellas. The Company will conduct research and pre-clinical development of any compound (as designated by Astellas) in each of the three programs in accordance with the terms of a research plan between the Company and Astellas. Astellas will have an exclusive worldwide license to develop and commercialize any such designated compound, subject to the Company’s rights to participate in cost and profit sharing in the United States, as described below.

Pursuant to the Astellas Agreement, the Company received from Astellas a one-time, nonrefundable, non-creditable, upfront payment of $90.0 million during the year ended December 31, 2022. Under ASC 808 and ASC 606, the Company determined that both parties are active participants in the activities and are exposed to significant risks and rewards dependent on the success of the development program, and identified four performance obligations under the Astellas Agreement as: (1) performance of services related to the first target program; (2) performance of services related to the second target program; (3) performance of services related to the third target program; and (4) the Company’s estimated future services on the collaboration JSC. The transaction price of $90.0 million was allocated among the performance obligations using the Company’s best estimate of the standalone selling price, or SSP, for each of the associated performance obligations. Revenue allocated to the three target programs, which totaled $89.1 million, is being recognized on a proportion of performance basis, using FTE cost as the basis of measurement, with such performance expected to occur over an estimated service period of four years for each target program. As it pertains to the JSC performance obligation, the revenue allocated to such performance obligation was $0.9 million, and is being recognized on a proportion of performance basis using FTE cost as the basis of measurement, and such effort is expected to be incurred on a relatively consistent basis throughout the term of the Astellas Agreement.

Additionally, under ASC 606, the Company determined a financing component associated with the $90.0 million upfront payment and has calculated $32.6 million as of December 31, 2022 on the unearned revenue portion beyond one year from the effective date of the agreement, which amount will be recognized as interest expense and revenue over the estimated service period for the three target programs.

The Company is also eligible to receive up to $422.5 million in development, regulatory and commercial milestones for each product candidate, and tiered royalties ranging from low double-digit to mid-teen percentages on worldwide sales of any commercial products that may result from the collaboration, subject to customary deductions under certain circumstances. The Company can also elect to convert any product candidate into a cost and profit-sharing arrangement, for the United States only. In the event the Company makes such election, it will share commercialization costs and profits relating to such product candidate equally with Astellas in the United States, and no royalties will be due from Astellas for net sales of such product candidates in the United States.

The Astellas Agreement contains customary provisions for termination, including by Astellas for convenience upon 30 days’ written notice and by either party for cause, including for material breach (subject to cure). The Company has certain reversion rights as to product candidates in connection with certain termination events.

Revenues under the Astellas Agreement were as follows:

Year ended December 31,

(in thousands)

Research and development services 1,878 - -

Financing component on unearned revenue 5,079 - -

Total revenue $ 10,897 $ - $ -

As of December 31, 2022 and 2021, there was $86.1 million and zero deferred revenue, respectively, related to the upfront payment received by the Company under the Astellas Agreement.

Collaboration with Vaxcyte

Vaxcyte Supply Agreement

In May 2018, the Company entered into a Supply Agreement (the “Supply Agreement”) with Vaxcyte, wherein Vaxcyte engaged the Company to provide research and development services and to supply extracts and custom reagents, as requested by Vaxcyte. The pricing is based on an agreed upon cost-plus arrangement.

During 2020, upon Vaxcyte’s request and their agreement to reimburse the related costs, the Company entered into agreements with third-party contract manufacturing organizations, or CMOs, to conduct process transfers to allow for such CMOs to manufacture and supply extract and custom reagents for Vaxcyte. As part of the agreement with Vaxcyte, should the Company decide to purchase extract from the extract CMO, the Company would be required to reimburse Vaxcyte for a portion of all incurred process transfer costs. As of December 31, 2022 and 2021, there was $4.8 million and $2.3 million in such accruals related to the Vaxcyte Supply Agreement.

For the year ended December 31, 2022 and 2021, the agreed-upon reimbursements by Vaxcyte of the costs associated with such arrangements, principally for pass-through costs from the CMOs, were $12.4 million and $8.9 million, respectively, and were accounted for by the Company as a reduction to research and development expense based on the Company’s conclusion that Vaxcyte was not a customer for such activities and associated payments.

Revenues under the Vaxcyte Supply Agreementwere as follows:

Year ended December 31,

(in thousands)

Vaxcyte Agreement

In December 2022, the Company entered into a letter agreement (the “Vaxcyte Agreement”) with Vaxcyte under which the Company granted to Vaxcyte (i) authorization to enter into an agreement with an independent alternate CMO to source cell-free extract solely for the products it licensed from the Company, allowing Vaxcyte to have direct oversight over financial and operational aspects of the relationship with the CMO (“CMO Relationship Rights”), and (ii) a right, but not an obligation, to obtain certain exclusive rights to internally manufacture and/or source extract from certain CMOs and the right to independently develop and make improvements to extract for use in connection with the exploitation of certain vaccine compositions (the “Option”). The Option is exercisable for five years following the effective date of the Vaxcyte Agreement (the “Option Period”), subject to potential acceleration in the event of a change of control of Vaxcyte.

Pursuant to the Vaxcyte Agreement, the Company received a one-time, nonrefundable, non-creditable, upfront payment of $10.0 million in cash, and 167,780 shares of Vaxcyte common stock with a fair value of $7.5

million in December 2022. The Company will receive an additional nonrefundable, non-creditable payment of $5.0 million after the Company and Vaxcyte mutually agree in writing upon the Form Definitive Agreement that will become effective upon Vaxcyte’s exercise of the Option. In the event Vaxcyte elects to exercise the Option, Vaxcyte will pay the Company $75.0 million in cash in two installments, and upon the occurrence of certain regulatory milestones, certain additional milestone payments totaling up to $60.0 million. In the event that Vaxcyte undergoes a change of control, and subsequently exercises the Option, a substantial majority of the milestone payments will be accelerated.

The Company evaluated the terms of the Vaxcyte Agreement and concluded that the Vaxcyte Agreement is considered a new standalone contract and distinct from the previously existing agreements with Vaxcyte. Under ASC 606, the Company determined that Vaxcyte is a customer for this arrangement and identified the promised goods and services under the Vaxcyte Agreement as: (1) the Option; (2) the Form Definitive Agreement; (3) CMO Relationship Rights; and (4) Joint steering committee participation. The Company concluded that the promises within the contract are interrelated and interdependent of one another. As such, these are not considered distinct but are combined as a single performance obligation. This single performance obligation is considered a material right as it provides Vaxcyte with the right to acquire additional goods at a price it would not have received without having entered into the Vaxcyte Agreement. Other than the upfront cash and stock payments received, all other payment provisions in the Vaxcyte Agreement were considered constrained variable consideration or otherwise not eligible for revenue recognition at inception and as of December 31, 2022. Revenue for the single performance obligation was deferred and will be eligible to begin to be recognized at the earlier of when the Option is exercised or expires.

As of December 31, 2022 and 2021, there was $17.5 million and zero deferred revenue, respectively, related to the upfront cash and stock payments received by the Company under the Vaxcyte Agreement.

BioNova Option Agreement

In October 2021, the Company entered into an agreement with BioNova granting BioNova the option to obtain exclusive rights to develop and commercialize STRO-001 in China, Hong Kong, Macau and Taiwan (“Greater China”) and amended the BioNova Option Agreement with BioNova in the first quarter of 2023. BioNova will pursue the clinical development, regulatory approval, and commercialization of STRO-001 in multiple indications, including non-Hodgkin's lymphoma, multiple myeloma, and leukemia in the licensed territory. The Company will retain development and commercial rights of STRO-001 globally outside of Greater China, including the United States.

Under the BioNova Option Agreement, BioNova paid the Company an initial licensing option payment of $4.0 million, with potential payments totaling up to $199.0 million related to the initial licensing option payment, option exercise, development, regulatory, and commercial milestones. The Company will provide STRO-001 to BioNova under appropriate clinical and commercial supply service agreements. Upon commercialization, the Company is eligible to receive tiered royalties ranging from low- to mid-teen percentages based on annual net sales of STRO-001 in Greater China for at least ten years following the first commercial sale of STRO-001 in Greater China. In February 2023, BioNova announced that the first patient has been dosed in the phase 1 clinical study of STRO-001.

The Company identified a combined performance obligation under the initial license option agreement, which consists of four interrelated promises: generating a recommended dose of STRO-001 for multiple myeloma and Non-Hodgkin’s lymphoma; providing licensed know-how and regulatory filings necessary to prepare an IND; providing initial clinical supply in the People’s Republic of China; and participating in the JSC. These promises are considered to be interdependent and not distinct from each other, representing a combined output. The transaction price at inception included the refundable initial licensing option payment of $4.0 million and was considered constrained at the inception of the agreement. During the year ended December 31, 2022, the Company recognized the $4.0 million licensing option payment as revenue after the Company performed the combined performance obligation under the BioNova Option Agreement. BioNova has the right to exercise the license option for an additional payment of $12.0 million. As of December 31, 2022, there was no deferred revenue under the BioNova Option Agreement and BioNova had not yet exercised the license option.

Tasly License Agreement

In December 2021, the Company entered into a license agreement with Tasly to grant Tasly an exclusive license to develop and commercialize STRO-002, or luveltamab tazevibulin, or luvelta, in Greater China (the

“Tasly License Agreement”). Tasly will pursue the clinical development, regulatory approval, and commercialization of luvelta in multiple indications, including ovarian cancer, non-small cell lung cancer, triple-negative breast cancer, and other indications in Greater China. The Company will retain development and commercial rights of luvelta globally outside of Greater China, including the United States.

Under the Tasly License Agreement, Tasly was obligated to make to the Company an initial nonrefundable upfront payment of $40.0 million, with additional potential payments totaling up to $345 million related to development, regulatory and commercialization contingent payments and milestones. The Company will provide luvelta to Tasly under appropriate clinical and commercial supply service agreements. Upon commercialization, the Company will receive tiered royalties, ranging from low- to mid-teen percentages based on annual net sales of luvelta in Greater China for at least ten years following the first commercial sale of luvelta in Greater China.

The Company determined that the Tasly License Agreement falls within the scope of ASC 808, as both parties are active participants in the activities and are exposed to significant risks and rewards dependent on the success of the commercialization of indications for luvelta in Greater China. The Company concluded that the Tasly License Agreement contained the following units of account: i) licensed know-how and Sutro patents, license to trademark rights, and initial regulatory data and information necessary to prepare an IND; and ii) collaboration governance and information sharing activities, such as JSC participation and ongoing regulatory and pharmacovigilance support.

The promises related to the licensed know-how and Sutro patents, license to trademark rights, and initial regulatory data and information necessary to prepare an IND are considered to be interdependent and not distinct from each other, representing a combined output. The Company determined that these promises are capable of being distinct from the collaboration governance and information sharing activities discussed below and further determined that this unit of account is a vendor-customer relationship and will account for it in accordance with ASC 606. The transaction price at inception included fixed consideration consisting of the upfront payment of $40.0 million. All potential future milestones and other payments were considered constrained at the inception of the Tasly License Agreement since the Company could not conclude it was probable that a significant reversal in the amount of revenue recognized would not occur. Since there is only one performance obligation accounted for under ASC 606, no allocation of the transaction price was necessary.

The Company determined that the unit of account consisting of collaboration governance and information sharing activities, such as JSC participation and ongoing regulatory and pharmacovigilance support, do not represent a customer-vendor relationship between the Company and Tasly. These promises are considered to be interdependent and not distinct from each other, representing a combined output. However, the Company determined that these promises are capable of being distinct from the intellectual property and data license promises discussed above. As such, based on the nature of the agreement and collaborative activities, the Company determined that the costs associated with these governance and information sharing activities performed under the agreement will be included in research and development expenses in the Statements of Operations, with any reimbursement of costs by Tasly reflected as a reduction of such expenses. During the year ended December 31, 2022 and 2021, the Company did not recognize a reduction of research and development expenses under the Tasly License Agreement.

On December 24, 2021, the effective date of the Tasly License Agreement, the Company satisfied its only performance obligation related to the $40.0 million upfront payment by delivering to Tasly the license, know-how and data required under the Tasly License Agreement. Following the satisfaction of such performance obligation, under the Tasly License Agreement, Tasly was obligated to pay the Company the $40.0 million upfront payment. In February 2022, Tasly indicated to the Company that it would like to discuss and renegotiate the terms of the Tasly License Agreement. As any renegotiation could affect the amount and timing of Tasly’s obligations under the terms of the Tasly License Agreement, including the upfront payment, the Company concluded that it would not recognize the $40.0 million upfront payment as revenue as of December 2021.

In April 2022, the Company entered into amendment No. 1 (the “Tasly Amendment”) to the Tasly License Agreement with Tasly. Pursuant to the Tasly Amendment, the initial nonrefundable upfront payment due by Tasly was amended to $25.0 million, and a $15.0 million payment will become payable to the Company upon the achievement of certain regulatory milestones. The Tasly Amendment also added an additional regulatory milestone payment to the Tasly License Agreement, providing additional potential payments totaling up to $350.0 million related to development, regulatory and commercialization milestones, beyond the payments described above, and made certain other ministerial edits.

During the year ended December 31, 2022, the Company recognized the $25.0 million upfront payment as revenue after the payment, net of a withholding tax, was received by the Company from Tasly. The withholding tax of $2.5 million was recorded as an income tax charge related to the upfront payment.

6. Property and Equipment, Net

Property and equipment, net, consists of the following:

December 31,

(in thousands)

Computer equipment and software $ 1,536 $ 1,353

Furniture and office equipment 247 237

Less accumulated depreciation and amortization (37,905 ) (33,426 )

Total property and equipment, net $ 24,621 $ 22,550

Depreciation and amortization expense amounted to $5.7 million, $4.8 million and $4.3 million for the years ended December 31, 2022, 2021 and 2020, respectively.

7. Loan and Security Agreement

In August 2017, the Company entered into a loan and security agreement with Oxford Finance LLC (“Oxford”) and Silicon Valley Bank (“SVB”) under which it borrowed $15.0 million (the “August 2017 Loan”). In connection with the August 2017 Loan, the Company issued to Oxford and SVB a warrant to purchase the Company’s Series D-2 redeemable convertible preferred stock (the “2017 Warrant”). The 2017 Warrants were later converted into warrants to purchase Series E redeemable convertible preferred stock in May and July 2018, and upon the Company’s IPO on October 1, 2018, all Series E redeemable convertible preferred stock warrants were converted to warrants to purchase 46,359 shares of common stock.

On February 28, 2020, (the “Effective Date”), the Company entered into a loan and security agreement (the “Loan and Security Agreement”) with Oxford as the collateral agent and a lender, and SVB as a lender (together with Oxford, the “Lenders”), pursuant to which the Lenders agreed to lend the Company up to an aggregate of $25.0 million (the “Term A Loan”). Upon entering into the Loan and Security Agreement, the Company borrowed $25.0 million from the Lenders, with approximately $9.6 million of such amount applied to the repayment of the outstanding principal, interest and final payment fees owed pursuant to the August 2017 Loan. As such, the August 2017 Loan has been paid in full. The Company accounted for the issuance of the Loan and Security Agreement and repayment of the August 2017 Loan as a debt modification. The associated unamortized debt discount on the August 2017 Loan and new lender fees from the debt issuance will be amortized as interest expense using the effective interest method until the maturity date of the Term A Loan.

In June 2022, the Company entered into an amendment to the Loan and Security Agreement with Oxford and SVB (the “LSA Amendment”). The LSA Amendment added a financial covenant that requires the Company to maintain a minimum unrestricted cash balance of $10.0 million. The Company was in compliance with the financial covenant under the LSA Amendment as of December 31, 2022. See “Note 14. Subsequent Events” for additional information on the amendment to the Loan and Security Agreement.

The Company’s obligations under the Loan and Security Agreement are secured by all assets of the Company, other than its intellectual property. The Company has also agreed not to encumber its intellectual property assets, except as permitted by the Loan and Security Agreement.

The Term A Loan matures on March 1, 2024 (the “Maturity Date”) and was interest-only through March 1, 2022, followed by 24 equal monthly payments of principal and interest.The Term A Loan will bear interest at a floating per annum rate equal to the greater of (i) 8.07% or (ii) the sum of (a) the greater of (1) the thirty (30) day U.S. LIBOR rate reported in the Wall Street Journal on the last business day of the month that immediately precedes the month in which the interest will accrue or (2) 1.67%, plus (b) 6.40%.

The Company will be required to make a final payment of 3.83% of the original principal amount of the Term A Loan, or $1.0 million, payable on the earlier of (i) the Maturity Date, (ii) the acceleration of the Term A Loan, or (iii) the prepayment of the Term A Loan (the “Final Payment”). The final payment amount is accreted as interest expense until the Maturity Date using the effective interest method. The Company may prepay all, but not less than all, of the Term A Loan upon 30 days’ advance written notice to Oxford, provided that the Company will be obligated to pay a prepayment fee equal to (i) 3.00% of the principal amount of the Term A Loan prepaid on or before the first anniversary of the applicable funding date, or (ii) 2.00% of the principal amount of the Term A Loan prepaid between the first and second anniversary of the applicable funding date, or (iii) 1.00% of the principal amount of the Term A Loan prepaid thereafter, and prior to the Maturity Date (each, a “Prepayment Fee”).

The Loan and Security Agreement contains customary affirmative and restrictive covenants, including covenants regarding incurrence of additional indebtedness or liens, investments, transactions with affiliates, delivery of financial statements, maintenance of inventory, payment of taxes, maintenance of insurance, protection of intellectual property rights, dispositions of property, business combinations or acquisitions, among other customary covenants. The Company is also restricted from paying dividends or making other distributions or payments on its capital stock, subject to limited exceptions. The Loan and Security Agreement provides that an event of default will occur if, among other triggers, there occurs any circumstances that could reasonably be expected to result in a material adverse change in the business, or operations or condition (financial or otherwise) of the Company or a material impairment of the prospect of the Company to repay any portion of its obligations under the Agreement. The Agreement also includes customary representations and warranties, other events of default and termination provisions.

In connection with entering into the Loan and Security Agreement, the Company issued to the Lenders warrants exercisable for 81,257 shares of the Company’s common stock (the “2020 Warrants”). The 2020 Warrants are exercisable in whole or in part, immediately, and have a per share exercise price of $9.23, which is the closing price of the Company’s common stock reported on the Nasdaq Global Market on the day prior to the Effective Date. The 2020 Warrants will terminate on the earlier of February 28, 2030 or the closing of certain merger or consolidation transactions. The estimated fair value upon issuance of the Warrants of $0.6 million is recorded as a debt discount on the associated borrowings on the Company’s balance sheet. The debt discount is being amortized to interest expense over the expected repayment period of the loan using the effective-interest method.

As of December 31, 2022 and 2021, accrued interest expense was $0.1 million and $0.2 million, respectively.

During the years ended December 31, 2022, 2021 and 2020, the Company recorded interest expense related to loans outstanding of $2.4 million, $2.6 million and $2.3 million, respectively, with average interest rates of 8.72%, 8.07% and 8.08%, respectively, which includes interest related to the accretion of debt discount of $0.5 million, $0.6 million and $0.5 million, respectively.

Long-term debt and net premium balances are as follows:

December 31,

(in thousands)

Principal amount of debt outstanding $ 15,625 $ 25,000

Less: Debt, current portion (12,500 ) (9,375 )

Future minimum payments of principal and estimated payments of interest on the Company’s Loan and Security Agreement as of December 31, 2022 are as follows:

Year Ending December 31: Amount

(in thousands)

Total future maturities 17,438

Less: amount representing interest (855 )

Less: final payment (958 )

Total principal amount of debt outstanding $ 15,625

8. Commitments and Contingencies

Leases

In June 2021, the Company entered into a third amendment (the “Third Amendment”) to its manufacturing facility lease, dated May 18, 2011, as amended, by and between Alemany Plaza LLC, located in San Carlos, California (the “San Carlos Lease”), as an extension to the term of the San Carlos Lease for a period of five years (the “Lease Extension Period”). Pursuant to the Third Amendment, the San Carlos Lease will expire on July 31, 2026, and it includes an option to renew the San Carlos Lease for an additional five years. The aggregate estimated base rent payments due over the Lease Extension Period is approximately $4.2 million, subject to certain terms contained in the San Carlos Lease.

In June 2021, the Company entered into a first amendment (the “First Amendment”) to its manufacturing support facility lease, dated May 4, 2015, as amended, by and between 870 Industrial Road LLC, located in San Carlos, California (the “Industrial Lease”), as an extension to the term of the Industrial Lease for a period of five years (the “Industrial Lease Extension Period”). Pursuant to the first Amendment, the Industrial Lease will expire on June 30, 2026, and it includes an option to renew the Industrial Lease for an additional five years. The aggregate estimated base rent payments due over the Industrial Lease Extension Period is approximately $4.3 million, subject to certain terms contained in the Industrial Lease.

In September 2020, the Company entered into a sublease agreement (the “Sublease”) with Five Prime Therapeutics, Inc. (the “Sublessor”), for approximately 115,466 square feet, in a building located in South San Francisco, California (the “Premises”). The Company uses the Premises as its corporate headquarters and to conduct (or expand) research and development activities. The Company commenced making monthly payments for the first 85,755 square feet of the Premises (“Initial Premises”) in July 2021, with occupancy of such space commencing in August 2021. The Company was provided early access to the Initial Premises commencing in the fourth quarter of 2020 to conduct certain planning and tenant improvement work. The Sublease is subordinate to the lease agreement, effective December 12, 2016, between the Sublessor and HCP Oyster Point III LLC (the “Landlord”). The commencement date for the remaining 29,711 square feet of the Premises (the “Expansion Premises”) is expected to be 24 months following the commencement date on the Initial Premises, although the Company has the right to accelerate the commencement date on the Expansion Premises to an earlier date upon six months’ prior written notice to the Sublessor. The Sublease for both the Initial Premises and Expansion Premises will expire on December 31, 2027. With a commencement date on the Initial Premises of July 1, 2021, the aggregate estimated base rent payments due over the term of the Sublease are approximately $39.1 million, including the approximately $5.2 million in potential financial benefit to the Company of base rent abatement to be provided by Sublessor, subject to certain terms contained in the Sublease. The Sublease contains customary provisions requiring the Company to pay its pro rata share of utilities and a portion of the operating expenses and certain taxes, assessments and fees of the Premises and provisions allowing the Sublessor to terminate the Sublease upon the termination of the lease with the Landlord or if the Company fails to remedy a breach of certain of its obligations within specified time periods. Additionally, the Company posted a security deposit of $0.9 million, which is reflected as restricted cash in non-current assets on the Company’s Balance Sheets as of December 31, 2022 and 2021.

The Company recognizes rent expense for these operating leases on a straight-line basis over the lease period. The components of lease costs, which the Company includes in operating expenses in the Statements of Operations, were as follows:

Year ended December 31,

(in thousands)

Short-term lease cost 82 117

During the years ended December 31, 2022 and 2021, the Company recorded operating lease expense of $6.2 million and $8.4 million, respectively, and paid $1.7 million and $6.2 million, respectively, of operating lease payments related to the lease liabilities, which the Company includes in net cash provided by (used in) operating activities in the Statements of Cash Flows. Under the historical guidance of ASC 840, rent expense was $4.7 million for the year ended December 31, 2020.

As of December 31, 2022 and 2021, the weighted-average remaining lease term was 4.8 years and 5.7 years, respectively, and the weighted-average discount rate used to determine the operating lease liability was 10.8% for both years.

As of December 31, 2022, the maturities of the Company’s operating lease liabilities were as follows:

Year Ending December 31, Amount

(in thousands)

Thereafter -

Total lease payments 44,037

Less: imputed interest (9,878 )

Operating lease liabilities 34,159

Less: current portion (4,585 )

Total lease liabilities, non-current $ 29,574

Indemnification & Other

In the ordinary course of business, the Company may provide indemnifications of varying scope and terms to vendors, lessors, business partners, board members, officers, and other parties with respect to certain matters, including, but not limited to, losses arising out of breach of such agreements, services to be provided by the Company, negligence or willful misconduct of the Company, violations of law by the Company, or from intellectual property infringement claims made by third parties. In addition, the Company has entered into indemnification agreements with directors and certain officers and employees that will require the Company, among other things, to indemnify them against certain liabilities that may arise by reason of their status or service as directors, officers or employees. No demands have been made upon the Company to provide indemnification under such agreements, and thus, there are no claims that the Company is aware of that could have a material effect on the Company’s Balance Sheets, Statements of Operations, or Statements of Cash Flows. The Company currently has directors’ and officers’ liability insurance.