KPTI US Equity☆

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

The following discussion and analysis of our financial condition and results of operations is meant to provide material information relevant to an assessment of the financial condition and results of operations of our company, including an evaluation of the amounts and uncertainties of cash flows from operations and from outside resources, so as to allow investors to better view our company from management’s perspective. You should read the following discussion and analysis of our financial condition and results of operations in conjunction with our consolidated financial statements and related notes included elsewhere in this report. Some of the information contained in this discussion and analysis and set forth elsewhere in this report, including information with respect to our plans and strategy for our business, includes forward-looking statements that involve risks and uncertainties. You should review the section entitled “Risk Factors” in Part I - Item 1A of this report for a discussion of important factors that could cause actual results to differ materially from the results described in or implied by the forward-looking statements contained in the following discussion and analysis.

Overview

We are a commercial-stage pharmaceutical company pioneering novel cancer therapies and dedicated to the discovery, development and commercialization of first-in-class drugs directed against nuclear export for the treatment of cancer. Our scientific expertise is based upon an understanding of the regulation of intracellular communication between the nucleus and the cytoplasm. We have discovered and are developing and commercializing novel, small molecule XPO1 inhibitor compounds that inhibit the nuclear export protein exportin 1 (“XPO1”). These compounds represent a new class of drug candidates with a novel mechanism of action that have the potential to treat a variety of diseases with high unmet medical need. Our lead asset, XPOVIO® (selinexor), was the first oral XPO1 inhibitor to receive marketing approval, receiving its initial U.S. approval from the U.S. Food and Drug Administration in July 2019, and is currently approved and marketed in the U.S. for the following indications:

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In combination with bortezomib and dexamethasone for the treatment of adult patients with multiple myeloma who have received at least one prior therapy. Approval in this indication was based on the results from the BOSTON (Bortezomib, Selinexor and Dexamethasone) trial;

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In combination with dexamethasone for the treatment of adult patients with relapsed or refractory multiple myeloma who have received at least four prior therapies and whose disease is refractory to at least two proteasome inhibitors, at least two immunomodulatory agents, and an anti-CD38 monoclonal antibody. Approval in this indication was based on the results from the STORM (Selinexor Treatment of Refractory Myeloma) trial; and

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For the treatment of adult patients with relapsed or refractory diffuse large B-cell lymphoma (“DLBCL”), not otherwise specified, including DLBCL arising from follicular lymphoma, after at least two lines of systemic therapy. This indication was approved under accelerated approval based on response rate and was based on the results from the SADAL (Selinexor Against Diffuse Aggressive Lymphoma) trial. Continued approval for this indication may be contingent upon verification and description of clinical benefit in a confirmatory trial.

Our primary focus is on marketing XPOVIO in its currently approved indications as well as developing and seeking regulatory approval of selinexor as an oral agent targeting multiple high unmet need cancer indications, including our lead clinical programs in myelofibrosis and endometrial cancer and our other late-stage clinical program in multiple myeloma. Depending on the data in our Phase 3 myelofibrosis and/or endometrial cancer programs and the availability of capital resources, we plan to explore opportunities to develop our leading next-generation XPO1 inhibitor, eltanexor, in additional myeloproliferative neoplasms and TP53 wild-type tumors.

The commercialization of XPOVIO in the U.S. is currently supported by sales representatives, nurse liaisons, and a market access team, as well as KaryForward®, an extensive patient and healthcare provider support program. Our commercial efforts are also supplemented by patient support initiatives coordinated by our dedicated network of participating specialty pharmacy providers.

The commercialization of XPOVIO and NEXPOVIO® (selinexor) (the brand name for selinexor in Europe and the United Kingdom) outside of the U.S. is managed by our partners in their respective territories. XPOVIO/NEXPOVIO has received regulatory approvals in various indications in 50 territories and countries outside the U.S. and is commercially available in a growing number of countries as our partners continue to secure reimbursement approvals.

In September 2025, we completed enrollment in our ongoing Phase 3 clinical trial to evaluate the efficacy and safety of once-weekly selinexor in combination with ruxolitinib versus placebo plus ruxolitinib in JAK2 inhibitor (“JAKi”)-naive myelofibrosis patients (the “SENTRY Trial”). We expect to report top-line data from the SENTRY Trial in March 2026. We continue to enroll JAKi-naïve myelofibrosis patients in the Phase 2 clinical trial to evaluate the safety and efficacy of selinexor as a monotherapy in patients with JAKi-naïve myelofibrosis with moderate thrombocytopenia (the “SENTRY-2 Trial”). The protocol, as amended in 2025,

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includes patients with platelet counts above 50,000 per microliter. We expect to report top-line data from all patients in the 60 mg cohort with at least 24 weeks of follow-up in the second half of 2026.

We are continuing to enroll patients in a global, Phase 3, randomized, double-blind trial evaluating selinexor as a maintenance-only therapy following systemic therapy in patients with TP53 wild-type advanced or recurrent endometrial cancer (the “XPORT-EC-042 Trial”). We expect to report top-line data from this event-driven trial in mid-2026.

In October 2025, we entered into a series of transactions with our term loan lenders, holders of our outstanding convertible notes and other investors to provide financial flexibility, additional working capital and equitize maturing notes (collectively, the “Financing Transactions”). The Financing Transactions included the following key components: (i) $27.5 million in new term loan borrowings and new convertible debt; (ii) $25.4 million of near-term deferrals of interest and royalty payments; (iii) a temporary reduction of $15.0 million in our minimum liquidity covenant; (iv) an exchange of $15.0 million aggregate principal amount of our convertible notes due 2029 for shares of common stock; (v) an exchange of $24.3 million aggregate principal amount of our convertible notes due October 15, 2025 for shares of our common stock and warrants to purchase shares of our common stock; and (vi) a private placement of shares of our common stock and warrants to purchase shares of our common stock for gross proceeds of approximately $8.8 million. In connection with the Financing Transactions, we issued an aggregate of 7,223,982 shares of common stock, pre-funded warrants to purchase an aggregate of 2,913,136 shares of common stock, and warrants to purchase an aggregate of 5,918,358 shares of common stock with an exercise price of $6.64 per share. In addition, we reduced the exercise price of outstanding warrants to purchase 3,068,417 shares from $16.50 to $6.64 per share.

Following consummation of the Financing Transactions, we had $116.5 million outstanding under our senior secured term loan with a maturity date in May 2028 (the “Amended Term Loan”), $15.0 million aggregate principal amount of 9.00% senior secured convertible notes due October 2028, $103.5 million aggregate principal amount of 9.00% senior secured convertible notes due May 2029, and $116.2 million of maximum remaining payments payable under our revenue interest financing agreement.

As of December 31, 2025, we had an accumulated deficit of $1.8 billion. We had net losses of $196.0 million, $76.4 million, and $143.1 million for the years ended December 31, 2025, 2024 and 2023, respectively. We recognized total revenue of $146.1 million in 2025, including $114.9 million of XPOVIO net product revenue and $31.2 million of license revenue. License revenue included $15.0 million of revenue for the reimbursement of development related expenses from the Menarini Group (“Menarini”). As of December 31, 2025, we had $63.7 million in cash, cash equivalents and investments. Based on our current business plan and current capital resources, combined with the uncertainty regarding the availability of additional funding or other strategic alternatives and considering our debt service obligations and financial covenant to maintain minimum liquidity, we have concluded that there is substantial doubt regarding our ability to continue as a going concern within one year after the date the accompanying consolidated financial statements are issued. See “Liquidity, Capital Resources, and Going Concern” below for a further discussion of our liquidity and the conditions that raise substantial doubt regarding our ability to continue as a going concern.

Critical Accounting Estimates

Our discussion and analysis of our financial condition and results of operations are based on our consolidated financial statements, which we have prepared in accordance with U.S. generally accepted accounting principles. The preparation of these consolidated 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 amounts of revenues and expenses during the reporting periods. We believe that the estimates and assumptions involved in the accounting policies described below may have the greatest potential impact on our consolidated financial statements and, therefore, consider these to be our critical accounting estimates. We evaluate our estimates and assumptions on an ongoing basis. Actual results may differ from these estimates under different assumptions and conditions. See Note 2, “Summary of Significant Accounting Policies”, to the consolidated financial statements included under Part II, Item 8 of this Annual Report on Form 10-K for information about our significant accounting policies.

Product Revenue Reserves

We recognize product revenue, net of variable consideration related to certain allowances and accruals, when the customer takes control of the product, which is upon delivery to the customer. Revenue from product sales is recorded at the net sales price, which includes estimates of variable consideration for which reserves are reported. These reserves are based on the amounts earned, or to be claimed on the related sales, and are generally classified as reductions of accounts receivable (if the amount is payable to the customer) or a current or long-term liability (if the amount is payable to a party other than a customer). Certain amounts are known at the time of sale based on contractual terms and are recorded pursuant to the most likely amount method, which is the single most likely amount in a range of possible considerations. Other amounts are estimated pursuant to the expected value method, which is the

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sum of probability-weighted amounts in a range of possible consideration amounts. Relevant factors used in the expected value method include: current contractual and statutory requirements, specific known market events and trends, industry data, and forecasted customer buying and payment patterns. These reserves reflect our best estimates of the variable consideration based on the terms of the respective underlying contracts.

The estimates for our product revenue allowances and accruals are most significantly affected by chargebacks, which are contractual commitments to provide products to qualified healthcare entities at prices lower than the list prices charged to our customers who purchase XPOVIO directly from us, and rebates that represent discount obligations under government programs, including Medicaid, Medicare, Tricare, the Department of Veterans Affairs, the Department of Defense, and others.

A 10% increase or decrease in these estimates would impact net product revenue by a corresponding increase or decrease of approximately $4.0 million.

License Agreements

We generate revenue from license or similar agreements with pharmaceutical companies for the development and commercialization of certain of our products and product candidates.

At contract inception, we evaluate all goods or services in the agreement to determine if they are distinct. If they are not distinct, they are combined with other promised goods or services to create a bundle of promised goods or services that are distinct. Distinct goods or services and distinct bundles of goods or services are considered performance obligations. Optional future services where any additional consideration paid to us reflects their standalone selling prices do not provide the customer with a material right and, therefore, are not considered performance obligations. Optional future services that are priced in a manner which provides the customer with a significant or incremental discount are considered performance obligations because they provide the customer with a material right.

We utilize judgment to estimate the transaction price at contract inception. We evaluate contingent milestones to determine if they should be included in the transaction price using the most likely amount method. Milestone payments that are not within our control, such as regulatory approvals, are not considered likely of being achieved until those approvals are received and are excluded from the transaction price using the most likely amount method. The transaction price is then allocated to each performance obligation on a relative standalone selling price basis, for which we recognize revenue as or when the performance obligations are satisfied. At the end of each reporting period, we re-evaluate our estimate of the transaction price including the probability of achieving milestone payments that may not be subject to a material reversal and adjust the transaction price if necessary. Any such adjustments are recorded on a cumulative catch-up basis, which would affect license and other revenue in the period of adjustment.

Accrued Research and Development Costs

We estimate our accrued research and development costs by reviewing quotes and contracts, identifying services that have been performed on our behalf, and estimating the associated cost incurred for services performed when we have not yet been invoiced or otherwise notified of the actual cost. Most of our service providers invoice us monthly in arrears for services performed or when contractual milestones are met. We make estimates of our accrued research and development costs at each balance sheet date in our financial statements based on facts and circumstances known to us at that time. We periodically confirm the accuracy of our estimates with the service providers and make adjustments if necessary. The significant estimates in our accrued research and development costs include fees incurred with contract research organizations (“CROs”) in connection with research and development activities, as well as fees to be paid to investigative sites in connection with clinical studies, for which we have not yet been invoiced.

We base our expenses related to CROs on our estimates of the services performed and efforts expended pursuant to quotes and contracts with CROs that conduct research and development activities on our behalf. The payment terms of these agreements are subject to negotiation, vary from contract to contract and may result in uneven payment flows. There may be instances in which payments made to our service providers will exceed the level of services performed and result in a prepayment. In accruing service fees, we estimate the time period over which the services will be performed and the level of effort to be expended in each period. If the actual timing of the performance of services or the level of effort varies from our estimates, we adjust the accrual or prepayment accordingly. Although we do not expect our estimates to be materially different from amounts actually incurred, if our estimates of the status and timing of services performed differ from the actual status and timing of services performed, it could result in us reporting amounts that are too high or too low in any particular period. To date, our estimates have not been materially different than amounts actually incurred.

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Financing Transactions

Our estimated value of the gain or loss on extinguishment of debt, the embedded derivatives in our convertible notes and the liability-classified common stock warrants on our consolidated balance sheets were valued using methodologies that incorporate certain unobservable inputs including (i) the volatility of our common stock price, (ii) our estimated credit spread and (iii) an estimate of when the warrants will be exercised based on an option pricing model. See the notes to the consolidated financial statements included under Part II, Item 8 of this Annual Report on Form 10-K for additional information.

Results of Operations

The following table summarizes our results of operations (in thousands, except for percentages):

For the Years Ended December 31,

Operating expenses:

Income tax provision (43 ) (57 ) 14 (25 )%

Product Revenue, net (in thousands, except for percentages)

For the Years Ended December 31,

To date, our only source of product revenue has been from the U.S. sales of XPOVIO. Net product revenue from U.S. commercial sales of XPOVIO for the year ended December 31, 2025 increased by $2.1 million compared to the year ended December 31, 2024, primarily due to higher net price year over year. Gross-to-net adjustments remained relatively consistent year over year and reflected lower 340B chargeback discounts in 2025, which were offset by higher Medicare Inflation Rebate charges and an increase to the product returns reserve.

License and Other Revenue (in thousands, except for percentages)

For the Years Ended December 31,

License and other revenue for the year ended December 31, 2025 decreased by $1.2 million as compared to the year ended December 31, 2024 primarily due to a decrease in milestone-related revenue from our other license agreements. The license agreements with Menarini and Antengene Therapeutics Limited (“Antengene”) are each defined and described in Note 5, “License Agreements”, to the consolidated financial statements included under Part II, Item 8 of this Annual Report on Form 10-K.

We expect license and other revenue to decrease as a result of the expiration of Menarini’s reimbursement of development-related expenses, which had previously provided up to $15.0 million in other revenue annually.

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Operating Expenses (in thousands, except for percentages)

For the Years Ended December 31,

Cost of Sales

Cost of sales for the year ended December 31, 2025 was relatively consistent with the year ended December 31, 2024.

Research and Development Expenses (in thousands, except for percentages)

For the Years Ended December 31,

Clinical trial and related costs:

Unallocated costs:

At any one time, we have a number of ongoing clinical development programs that we are conducting independently or in collaboration with third parties. We track our external clinical trial and related costs on a program-by-program basis. Our major programs include our lead clinical programs in myelofibrosis and endometrial cancer and our other late-stage clinical program in multiple myeloma. To the extent that external clinical trial and related costs are not attributable to a major program, they are included in “Other programs” and to the extent external clinical trial and related costs cannot be allocated to a specific program, they are included in “Non-program specific clinical trial and related costs.” We also have unallocated research and development costs, which we do not track on a program-by-program basis. These costs represent expenses incurred across multiple programs or to support our general research and development operations.

Research and development expenses for the year ended December 31, 2025 decreased by $17.6 million as compared to the year ended December 31, 2024, primarily due to lower personnel and stock-based compensation costs and reduced clinical trial spending. Personnel and stock-based compensation costs decreased by $9.7 million as a result of lower headcount and reduced contractor utilization following previously implemented cost reduction initiatives. In addition, clinical trial and related costs for selinexor in multiple myeloma decreased by $8.7 million, reflecting the reduced scope of our Phase 3 trial, including lower comparator drug expenses. These decreases were partially offset by a $5.0 million increase in clinical trial and related costs for selinexor in myelofibrosis, primarily driven by increased trial activity and higher patient enrollment.

We expect our research and development expenses to increase as we continue to support our ongoing Phase 3 trials as they progress from the enrollment phase to the maintenance phase. In the event of positive top-line data in any of our trials, we would expect to incur incremental costs primarily associated with regulatory filings.

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Selling, General and Administrative Expenses (in thousands, except for percentages)

For the Years Ended December 31,

Selling, general and administrative expenses for the year ended December 31, 2025 decreased by $10.2 million as compared to the year ended December 31, 2024, primarily due to reductions in personnel-related costs. Personnel costs decreased by $6.2 million and stock-based compensation decreased by $3.6 million, reflecting lower headcount resulting from our ongoing cost reduction initiatives. Consulting, professional and other costs remained relatively consistent year over year, as increases in professional fees, primarily legal fees, were more than offset by cost reduction measures in other areas, including marketing agencies and other commercial spend.

We expect selling, general and administrative expenses to remain relatively consistent. In the event of positive top-line data in any of our trials, we would expect to incur incremental costs related to launch preparation.

Other Income (Expense), net(in thousands, except for percentages)

For the Years Ended December 31,

Total other (expense) income, net for the year ended December 31, 2025 increased by $148.4 million compared to the year ended December 31, 2024. The increase was driven primarily by a $107.1 million increase in the loss on extinguishment of debt, reflecting a $62.4 million loss recorded in 2025 related to the Financing Transactions, compared to a $44.7 million gain recorded in 2024 from a separate refinancing transaction. In addition, other income, net decreased by $28.2 million, primarily due to non-cash remeasurement of embedded derivatives and liability-classified common stock warrants. Interest expense increased by $8.4 million, primarily due to debt issuances in 2024 and 2025 and higher interest rates on our debt following the Financing Transactions. Lastly, interest income decreased by $4.6 million due to lower investment balances in 2025 compared to 2024.

We expect total other (expense) income, net to decrease, primarily due to the debt extinguishment recorded in 2025 in connection with the Financing Transactions. We also expect interest expense to increase as a result of higher debt balances and interest rates in 2026 following the Financing Transactions. The future impact of remeasurements of embedded derivatives and liability-classified common stock warrants will depend on a variety of factors, including movements in our stock price, and cannot be forecasted.

Results of Operations - Years Ended December 31, 2024 and 2023

Discussion and analysis of the results of operations for the year ended December 31, 2024 as compared to the results of operations for the year ended December 31, 2023 is included under the heading “Item 7.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, 2024 as filed with the SEC on February 19, 2025 (“2024 Form 10-K”).

Liquidity, Capital Resources and Going Concern

Cash flows

We have historically financed our operations primarily through a combination of proceeds from (i) product revenue sales; (ii) public and private placements of equity securities; (iii) the issuance of convertible debt; (iv) a term loan; (v) our deferred royalty obligation; (vi) at the market offerings; and (vii) business development activities. As of December 31, 2025, our principal source of

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liquidity was $63.7 million of cash, cash equivalents and investments. We have had recurring losses since inception and incurred an operating loss of $90.7 million for the year ended December 31, 2025.

We anticipate that we will continue to incur significant operating losses in the foreseeable future. Based on our current business plan and current capital resources, combined with the uncertainty regarding the availability of additional funding or other strategic transactions and considering our debt service obligations and financial covenant to maintain minimum liquidity, we have concluded that there is substantial doubt regarding our ability to continue as a going concern within one year after the date the accompanying consolidated financial statements are issued. We expect that our existing liquidity, including cash, cash equivalents and investments as of December 31, 2025 as well as cash flow from net product revenue and license and other revenue, will enable us to fund our current operating plans into the second quarter of 2026. See “Liquidity, Capital Resources and Going Concern – Funding Requirements” below and Note 1 “Organization and Operations” to the consolidated financial statements included under Part II, Item 8 of this Annual Report on Form 10-K for a further discussion of our liquidity and the conditions that raise substantial doubt regarding our ability to continue as a going concern.

The following table provides information regarding our cash flows (in thousands):

For the Years Ended December 31,

Net Cash Used in Operating Activities

Net cash used in operating activities decreased by $52.1 million during the year ended December 31, 2025 compared to the year ended December 31, 2024. The decrease was primarily driven by lower cash disbursements resulting from reduced operating expenses and the deferral of cash interest and royalty payments associated with the Financing Transactions.

Net Cash Provided by Investing Activities

Net cash provided by investing activities decreased by $52.1 million during the year ended December 31, 2025 compared to the year ended December 31, 2024. Proceeds from the maturities of investments decreased by $111.1 million, partially offset by a $58.8 million decrease in purchases of investments, reflecting liquidity needs to fund our operations.

Net Cash Provided by Financing Activities

Net cash provided by financing activities decreased by $11.6 million during the year ended December 31, 2025 compared to the year ended December 31, 2024. The decrease was primarily driven by lower net proceeds from debt and equity financing in 2025 compared to 2024.

A discussion of changes in our financial condition for the year ended December 31, 2024 as compared to the year ended December 31, 2023 is included under the heading “Item 7. Management’s Discussion and Analysis of Financial Condition and Results of Operations” in the 2024 Form 10-K.

Sources of Liquidity

In October 2025, we entered into a securities purchase agreement with certain institutional investors to which we issued and sold, in a private placement, an aggregate of (i) 1,487,917 shares of common stock at a price per share of $5.88 and (ii) accompanying warrants to purchase 1,317,771 shares of common stock at an exercise price of $6.64 per share. We received aggregate gross proceeds of approximately $8.8 million.

In October 2025, we entered into a note purchase agreement pursuant to which issued and sold, in a private placement, $15.0 million aggregate principal amount of new 9.00% senior secured convertible notes due 2028 (the “2028 Notes”) to certain holders of our existing 6.00% senior secured convertible notes due 2029. The 2028 Notes are senior secured second-lien obligations and bear

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interest at a rate of 9.00% per year payable quarterly in arrears on March 31, June 30, September 30, and December 31 of each year, beginning on December 31, 2025. Interest will be paid in kind on December 31, 2025 and March 31, 2026 with cash interest payments beginning on June 30, 2026. The 2028 Notes will mature on October 15, 2028, unless earlier converted, redeemed or repurchased in accordance with their terms.

In September, 2019, we and certain of our subsidiaries entered into the Revenue Interest Financing Agreement with certain entities managed by HCRx, which was subsequently amended on June 23, 2021, August 1, 2023, May 8, 2024, August 14, 2025, August 27, 2025 and October 7, 2025 and which was assigned in July 2025 by HCRx to KKR in connection with its acquisition of a majority ownership stake in HCRx (the “Revenue Interest Agreement” and, as amended, the “Amended Revenue Interest Agreement”), pursuant to which, HCRx paid us a total of $135.0 million, less certain transaction expenses. In October 2025, we entered into the Sixth Amendment to the Revenue Interest Financing Agreement pursuant to which (i) HCRx waived our obligation to pay royalties on revenue recognized between April 1, 2025 and March 31, 2026 and (ii) we agreed to increase the Applicable Tiered Percentage (as defined in the Amended Revenue Interest Agreement ) to 8.00% beginning on April 1, 2026. The total amount payable under the Revenue Interest Financing Agreement will remain capped at $263.3 million. For additional information, see Note 10, “Long-Term Obligations”, to the consolidated financial statements included under Part II, Item 8 of this Annual Report on Form 10-K.

In May 2024, we entered into a credit and guaranty agreement (the “Credit Agreement”) with certain existing lenders and HCRx, which was subsequently assigned by HCRx to KKR in connection with its acquisition of a majority ownership stake in HCRx in July 2025, which provides for a senior secured term loan facility of $100.0 million (the “Term Loan”). In October 2025, we entered into the First Amendment and Waiver to Credit and Guaranty Agreement with the lenders party thereto and Wilmington Savings Fund Society, FSB, as administrative agent for the lenders and collateral agent (the “Amended Credit Agreement”), pursuant to which, among other things, the lenders provided $12.5 million principal amount of additional loans (the “Amended Term Loan”). The amendments to the Credit Agreement include, among other things (i) reducing the financial covenant requiring us to maintain liquidity of at least $10.0 million, subject to increase in the event we issue indebtedness for borrowed money or issue capital stock, through October 10, 2026, after which we will be required to maintain liquidity of at least $25.0 million and (ii) increasing the interest rate on borrowings under the Amended Term Loan to the secured overnight financing rate plus 10.25% for interest payments occurring after June 30, 2025. Interest on borrowings under the Amended Term Loan incurred from July 1, 2025 to October 10, 2025 were paid in kind at closing. Interest on borrowings will be paid in kind on December 31, 2025 and March 31, 2026 and cash interest payments will begin on June 30, 2026. For additional information, see Note 10, “Long-Term Obligations”, to the consolidated financial statements included under Part II, Item 8 of this Annual Report on Form 10-K.

In February 2023, we entered into an Open Market Sale Agreement (the “Open Market Sale Agreement”) with Jefferies LLC, as agent (“Jefferies”). Under the Open Market Sale Agreement, we may issue and sell shares of our common stock having an aggregate offering price of up to $100.0 million (the “Shares”) from time to time through Jefferies. We did not sell any Shares under the Open Market Sale Agreement during the year ended December 31, 2025. As of December 31, 2025, $100.0 million of Shares was available for issuance and sale under the Open Market Sale Agreement.

During the year ended December 31, 2025, we received $8.2 million in milestone under our license and distribution arrangements pursuant to which we are entitled to receive additional milestone payments, if certain development goals and sales milestones are achieved, as well as royalties on future net sales of the licensed and sold products in the territories under such arrangements. In addition, Menarini reimbursed us $15.0 million per calendar year, or $60 million in total, for development related expenses we incurred for selinexor from 2022 through 2025.

Commitments, Contingencies and Contractual Obligations

Operating Leases

We are party to an operating lease of office and research space in Newton, Massachusetts, which was amended in November 2024 and under which we currently lease a total of 52,224 square feet of office space through September 30, 2030.

Contractual Obligations

We have contractual obligations under our (i) Amended Credit Agreement; (ii) 2028 Notes; (iii) 9.00% convertible senior notes due 2029; and (iv) Amended Revenue Interest Agreement as disclosed in Note 10, “Long-Term Obligations”, to the consolidated financial statements included under Part II, Item 8 of this Annual Report on Form 10-K.

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Funding Requirements

We expect to continue to incur costs related to our clinical development programs as we continue to advance our lead clinical programs in myelofibrosis and endometrial cancer and our other late-stage clinical program in multiple myeloma, as well as commercialization expenses related to sales, marketing, manufacturing and distribution of our approved products, to the extent that these functions are not the responsibility of our collaborators.

Identifying potential product candidates and conducting preclinical studies and clinical trials is a time-consuming, expensive and uncertain process that takes years to complete. In addition, our product candidates for which we receive marketing approval may not achieve commercial success. Our ability to become and remain profitable depends on our ability to generate revenue. There can be no assurance as to the amount or timing of any such revenue, and we may not achieve profitability in the near-term, if at all, as described more fully in the risk factor entitled “We have incurred significant losses since inception, expect to continue to incur significant losses, and may never achieve or maintain profitability,” under the heading “Risk Factors” in this Annual Report on Form 10-K. Accordingly, we will need to continue to rely on additional financing to achieve our business objectives. Adequate additional financing may not be available to us on acceptable terms, or at all. We may seek additional capital due to favorable market conditions or strategic considerations, even if we believe we have sufficient funds for our current or future operating plans. If we are unable to raise capital when needed or on attractive terms, we would be forced to delay, reduce or eliminate our research and development programs or commercialization efforts.

Based on our current business plan and current capital resources, combined with the uncertainty regarding the availability of additional funding or other strategic alternatives and considering our debt service obligations and financial covenant to maintain minimum liquidity, we have concluded that there is substantial doubt regarding our ability to continue as a going concern within one year after the date the accompanying consolidated financial statements are issued. See Note 1, “Organization and Operations”, to the consolidated financial statements included under Part II, Item 8 of this Annual Report on Form 10-K for a further discussion of the conditions that raise substantial doubt regarding our ability to continue as a going concern.

We currently expect that our existing liquidity, including cash, cash equivalents and investments as well as cash flow from net product revenue and license and other revenue, will enable us to fund our current operating plans into the second quarter of 2026. We will require additional capital to complete the ongoing clinical development of selinexor, including the Phase 3 SENTRY Trial beyond top-line results and the Phase 3 XPORT-EC-042 Trial and the Phase 3 XPORT-MM-031/EMN29 trial. We plan to address the conditions that raise substantial doubt regarding our ability to continue as a going concern by, among other things, obtaining additional funding through equity offerings, debt financings and refinancings, collaborations, strategic alliances and/or licensing arrangements. We expect to evaluate opportunities to raise additional funds from time to time, including through the issuance and sale of shares of our common stock under our Open Market Sale Agreement and in connection with the reporting of data from our ongoing Phase 3 clinical trials. There is no assurance that such additional financing or strategic alternatives will be available on terms acceptable to us, or at all. Our ability to successfully raise additional funds or execute on a strategic alternative is dependent on a number of factors. If we are not able to successfully consummate a financing transaction or strategic alternative, our Board may explore a sale of assets or the initiation of bankruptcy proceedings under Chapter 11 of the U.S. Bankruptcy Code. Further, our indebtedness, as discussed under the risk factor titled “Our indebtedness could limit cash flow available for our operations, expose us to risks that could adversely affect our business, financial condition and results of operations and impair our ability to satisfy our obligations under the Amended Term Loan, the Convertible Notes or the Amended Revenue Interest Agreement,” under the heading “Risk Factors” in this Annual Report on Form 10-K, may be unattractive to potential sources of funding and strategic partners and may decrease our ability to consummate a financing transaction or enter into a strategic alternative. Additionally, the negotiation and consummation of a financing transaction or strategic alternative may be costly and time-consuming.

Our future long-term capital requirements will depend on many factors, as described more fully in the risk factor entitled “We will need additional funding or to enter into strategic alternatives to achieve our business objectives. If we are unable to raise sufficient capital or to enter into strategic alternatives on acceptable terms to meet our needs, we may be forced to delay, reduce or eliminate our research and development programs and/or commercialization efforts,” under the heading “Risk Factors” in this Annual Report on Form 10-K.

In addition to the expenses required to fund our operations described above, our funding requirements as of December 31, 2025 also include the following:

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Lease costs for our headquarters in Newton, Massachusetts of $9.4 million through September 30, 2030;

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Future obligations related to the Amended Credit Agreement of $153.2 million through May 8, 2028 in addition to the financial covenant to maintain minimum liquidity;

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Future obligations related to the 2028 Notes of $19.2 million through October 15, 2028;

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Future obligations related to the New 2029 Notes of $138.2 million through May 13, 2029;

•

Future royalty obligations to KKR under the Amended Revenue Interest Agreement of $116.2 million by September 26, 2035.

Item 7A. Quantitative and Qualitative Disclosures about Market Risk

We are exposed to market risk related to changes in interest rates. We had cash, cash equivalents and investments of $63.7 million as of December 31, 2025. Our primary exposure to market risk is interest rate sensitivity, which is affected by changes in the general level of U.S. interest rates. Due to the short-term duration of our investment portfolio and the low risk profile of our investments, an immediate 100 basis point shift in interest rates would not have a material effect on the fair market value of our investment portfolio.

We do not believe our cash, cash equivalents and investments have significant risk of default or illiquidity. While we believe our cash, cash equivalents and investments do not contain excessive risk, we cannot provide absolute assurance that in the future our investments will not be subject to adverse changes in securities at one or more financial institutions that are in excess of federally insured limits. Given the potential instability of financial institutions, we cannot provide assurance that we will not experience losses on these deposits and investments.

We are also exposed to market risk related to changes in foreign currency exchange rates. We contract with contract research organizations and contract manufacturing organizations that are located in Canada, the United Kingdom and Europe, which are denominated in foreign currencies. We also contract with a number of clinical trial sites outside of the U.S., and our budgets for those studies are frequently denominated in foreign currencies. We are subject to fluctuations in foreign currency rates in connection with these agreements. We do not currently hedge our foreign currency exchange rate risk.

Item 8. Financial Statements and Supplementary Data

The financial statements required to be filed pursuant to this Item 8 are appended to this Annual Report on Form 10-K and are incorporated herein by reference. An index of those financial statements is found in Item 15 of Part IV of this Annual Report on Form 10-K.

Item 9A. Controls and Procedures

Evaluation of Disclosure Controls and Procedures

We have established disclosure controls and procedures designed to ensure that information required to be disclosed in the reports that we file or submit under the Exchange Act is recorded, processed, summarized and reported within the time periods specified in the rules and forms prescribed by the Securities and Exchange Commission and is accumulated and communicated to management, including the principal executive officer (our President and Chief Executive Officer) and principal financial officer (our Executive Vice President, Chief Financial Officer and Treasurer), to allow timely decisions regarding required disclosure.

Our management, under the supervision and with the participation of our President and Chief Executive Officer and Executive Vice President, Chief Financial Officer and Treasurer, has evaluated the effectiveness of our disclosure controls and procedures (as defined in Rules 13a-15(e) and 15d-15(e) under the Exchange Act) as of the end of the period covered by this Annual Report on Form 10-K. Management recognizes that any disclosure controls and procedures, no matter how well designed and operated, can provide only reasonable assurance of achieving their objectives. Our disclosure controls and procedures have been designed to provide reasonable assurance of achieving their objectives. Based on such evaluation, our President and Chief Executive Officer and Executive Vice President, Chief Financial Officer and Treasurer concluded that our disclosure controls and procedures were effective at the reasonable assurance level as of December 31, 2025.

Management’s Annual Report on Internal Control Over Financial Reporting

Our management is responsible for establishing and maintaining adequate internal control over financial reporting, as such term is defined in Rules13a-15(f) and15d-15(f) of the Exchange Act. Because of its inherent limitations, internal control over financial reporting may not prevent or detect misstatements. Also, projections of any evaluation of effectiveness to future periods are subject to the risk that controls may become inadequate because of changes in conditions, or that the degree of compliance with policies or procedures may deteriorate. Our internal control over financial reporting is a process designed under the supervision of our principal executive officer and principal financial officer to provide reasonable assurance regarding the reliability of financial reporting and the

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preparation of our financial statements for external reporting purposes in accordance with U.S. generally accepted accounting principles.

Under the supervision and with the participation of management, including our principal executive officer and principal financial officer we conducted an evaluation of the effectiveness of our internal control over financial reporting based on the 2013 framework in Internal Control – Integrated Framework issued by the Committee of Sponsoring Organizations of the Treadway Commission. Based on our evaluation under that framework, management concluded that our internal control over financial reporting was effective as of December 31, 2025.

Our independent registered public accounting firm that audited the financial statements included in this Annual Report on Form 10-K has issued an attestation report on our internal control over financial reporting, which is included below.

Changes in Internal Control Over Financial Reporting

There were no changes in our internal control over financial reporting identified in connection with the evaluation required by Rule 13a-15(d) and 15d-15(d) of the Exchange Act that occurred during the quarter ended December 31, 2025 that have materially affected, or are reasonably likely to materially affect, our internal control over financial reporting.

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Report of Independent Registered Public Accounting Firm

To the Shareholders and the Board of Directors of Karyopharm Therapeutics Inc.

Opinion on Internal Control Over Financial Reporting

We have audited Karyopharm Therapeutics Inc.’s internal control over financial reporting as of December 31, 2025, based on criteria established in Internal Control—Integrated Framework issued by the Committee of Sponsoring Organizations of the Treadway Commission (2013 framework), (the COSO criteria). In our opinion, Karyopharm Therapeutics Inc. (the Company) maintained, in all material respects, effective internal control over financial reporting as of December 31, 2025, based on the COSO criteria.

We also have audited, in accordance with the standards of the Public Company Accounting Oversight Board (United States) (PCAOB), the 2025 consolidated financial statements of the Company and our report dated February 12, 2026 expressed an unqualified opinion thereon that included an explanatory paragraph regarding the Company’s ability to continue as a going concern.

Basis for Opinion

The Company’s management is responsible for maintaining effective internal control over financial reporting and for its assessment of the effectiveness of internal control over financial reporting included in the accompanying Management’s Annual Report on Internal Control Over Financial Reporting. Our responsibility is to express an opinion on the Company’s internal control over financial reporting based on our audit. We are a public accounting firm registered with the 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 audit in accordance with the standards of the PCAOB. Those standards require that we plan and perform the audit to obtain reasonable assurance about whether effective internal control over financial reporting was maintained in all material respects.

Our audit included obtaining an understanding of internal control over financial reporting, assessing the risk that a material weakness exists, testing and evaluating the design and operating effectiveness of internal control based on the assessed risk, and performing such other procedures as we considered necessary in the circumstances. We believe that our audit provides a reasonable basis for our opinion.

Definition and Limitations of Internal Control Over Financial Reporting

A company’s internal control over financial reporting is a process designed to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles. A company’s internal control over financial reporting includes those policies and procedures that (1) pertain to the maintenance of records that, in reasonable detail, accurately and fairly reflect the transactions and dispositions of the assets of the company; (2) provide reasonable assurance that transactions are recorded as necessary to permit preparation of financial statements in accordance with generally accepted accounting principles, and that receipts and expenditures of the company are being made only in accordance with authorizations of management and directors of the company; and (3) provide reasonable assurance regarding prevention or timely detection of unauthorized acquisition, use, or disposition of the company’s assets that could have a material effect on the financial statements.

Because of its inherent limitations, internal control over financial reporting may not prevent or detect misstatements. Also, projections of any evaluation of effectiveness to future periods are subject to the risk that controls may become inadequate because of changes in conditions, or that the degree of compliance with the policies or procedures may deteriorate.

/s/ Ernst & Young LLP

Boston, Massachusetts

February 12, 2026

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Item 9B. Other Information

Director and Officer Trading Arrangements

A portion of the compensation of our directors and officers (as defined in Rule 16a-1(f) under the Securities Exchange Act of 1934, as amended (the “Exchange Act”)) is in the form of equity awards and, from time to time, directors and officers engage in open-market transactions with respect to the securities acquired pursuant to such equity awards or other securities of our company, including to satisfy tax withholding obligations when equity awards vest or are exercised, and for diversification or other personal reasons.

Transactions in our securities by directors and officers are required to be made in accordance with our Insider Trading Policy, which requires that the transactions be in accordance with applicable U.S. federal securities laws that prohibit trading while in possession of material nonpublic information. Rule 10b5-1 under the Exchange Act provides an affirmative defense that enables directors and officers to prearrange transactions in our securities in a manner that avoids concerns about initiating transactions while in possession of material nonpublic information.

During the fourth quarter of 2025, none of our directors or officers adopted or terminated a Rule 10b5-1 trading arrangement or a non-Rule 10b5-1 trading arrangement (as defined in Item 408(c) of Regulation S-K).

Item 9C. Disclosure Regarding Foreign Jurisdictions that Prevent Inspections

Not applicable.

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PART III

Certain information required by Part III is omitted from this Annual Report on Form 10-K and is incorporated by reference from our definitive proxy statement relating to our 2026 annual meeting of stockholders, pursuant to Regulation 14A of the Exchange Act, which we refer to as our 2026 Proxy Statement. We expect to file our 2026 Proxy Statement with the SEC within 120 days of December 31, 2025.

Item 10. Directors, Executive Officers and Corporate Governance

Information regarding our directors, including the audit committee and audit committee financial experts, insider trading policies and procedures and compliance with Section 16(a) of the Exchange Act, if applicable, will be included in our 2026 Proxy Statement and is incorporated herein by reference. Information regarding our executive officers is set forth in “Business - Information about our Executive Officers” in Part I, Item 1 of this Annual Report on Form 10-K.

We have adopted a Code of Ethics and Business Conduct for all of our directors, officers and employees as required by Nasdaq governance rules and as defined by applicable SEC rules. Stockholders may locate a copy of our Code of Ethics and Business Conduct on our website at www.karyopharm.com or request a copy without charge from:

Karyopharm Therapeutics Inc.

Attention: Investor Relations

85 Wells Avenue, 2nd Floor

Newton, MA 02459

We will post to our website any amendments to the Code of Ethics and Business Conduct and any waivers that are required to be disclosed by the rules of either the SEC or Nasdaq.

Item 11. Executive Compensation

The information required by this Item 11 of Form 10-K regarding executive compensation will be included in our 2026 Proxy Statement and, other than the information required by Item 402(v) of Regulation S-K, is incorporated herein by reference.

Item 12. Security Ownership of Certain Beneficial Owners and Management and Related Stockholder Matters

The information required by this Item 12 of Form 10-K regarding security ownership of certain beneficial owners and management and securities authorized for issuance under equity compensation plans will be included in our 2026 Proxy Statement and is incorporated herein by reference.

Item 13. Certain Relationships and Related Transactions, and Director Independence

The information required by this Item 13 of Form 10-K regarding certain relationships and related transactions and director independence will be included in our 2026 Proxy Statement and is incorporated herein by reference.

Item 14. Principal Accountant Fees and Services

The information required by this Item 14 of Form 10-K regarding principal accountant fees and services will be included in our 2026 Proxy Statement and is incorporated herein by reference.

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PART IV

Item 15. Exhibits and Financial Statement Schedules

(a)(1) Financial Statements

The financial statements listed below are filed as a part of this Annual Report on Form 10-K.

Pagenumber

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

Notes to Consolidated Financial Statements 132

(a)(2) Financial Statement Schedules

All financial schedules have been omitted because the required information is either presented in the consolidated financial statements or the notes thereto or is not applicable or required.

(a)(3) Exhibits

The exhibits required by Item 601 of Regulation S-K and Item 15(b) of this Annual Report on Form 10-K are listed in the Exhibit Index immediately preceding the signature page of this Annual Report on Form 10-K and are incorporated herein.

Item 16. Form 10-K Summary

None.

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Report of Independent Registered Public Accounting Firm

To the Shareholders and the Board of Directors of Karyopharm Therapeutics Inc.

Opinion on the Financial Statements

We have audited the accompanying consolidated balance sheets of Karyopharm Therapeutics Inc. (the Company) as of December 31, 2025 and 2024, the related consolidated statements of operations, comprehensive loss, stockholders’ deficit and cash flows for each of the three years in the period ended December 31, 2025, and the related notes (collectively referred to as the “consolidated financial statements”). In our opinion, the consolidated financial statements present fairly, in all material respects, the financial position of the Company at December 31, 2025 and 2024, and the results of its operations and its cash flows for each of the three years in the period ended December 31, 2025, in conformity with U.S. generally accepted accounting principles.

We also have audited, in accordance with the standards of the Public Company Accounting Oversight Board (United States) (PCAOB), the Company’s internal control over financial reporting as of December 31, 2025, based on criteria established in Internal Control—Integrated Framework issued by the Committee of Sponsoring Organizations of the Treadway Commission (2013 framework), and our report dated February 12, 2026 expressed an unqualified opinion thereon.

The Company’s Ability to Continue as a Going Concern

The accompanying consolidated financial statements have been prepared assuming that the Company will continue as a going concern. As discussed in Note 1 to the financial statements, the Company has incurred significant operating losses since inception, expects to incur significant operating losses for the foreseeable future and has stated that substantial doubt exists about the Company’s ability to continue as a going concern. Management’s evaluation of the events and conditions and management’s plans regarding these matters are also described in Note 1. The consolidated financial statements do not include any adjustments that might result from the outcome of this uncertainty.

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 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. 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 Matters

The critical audit matters communicated below are matters arising from the current period audit of the financial statements that were 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 critical audit matters does not alter in any way our opinion on the consolidated 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 matters or on the accounts or disclosures to which they relate.

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Accrued Clinical Trial Costs

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Debt Extinguishment and Modification

/s/ Ernst & Young LLP

We have served as the Company’s auditor since 2014.

Boston, Massachusetts

February 12, 2026

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Karyopharm Therapeutics Inc.

Consolidated Balance Sheets

(in thousands, except per share amounts)

Assets

Current assets:

Prepaid expenses and other current assets 9,186 12,245

Property and equipment, net 104 400

Operating lease right-of-use assets 4,548 5,884

Liabilities and stockholders’ deficit

Current liabilities:

Senior secured term loan 21,010 —

Operating lease liabilities 969 438

Senior secured term loan, net of current portion 94,795 94,603

Operating lease liabilities, net of current portion 5,743 6,712

Stockholders’ deficit:

Accumulated other comprehensive income (loss) 71 (356 )

Total liabilities and stockholders’ deficit $ 108,416 $ 164,418

The accompanying notes are an integral part of these consolidated financial statements.

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Karyopharm Therapeutics Inc.

Consolidated Statements of Operations

(in thousands, except per share amounts)

For the Years Ended December 31,

Revenues:

Operating expenses:

Other income (expense):

(Loss) gain on extinguishment of debt (62,365 ) 44,702 —

Income tax provision (43 ) (57 ) (323 )

Basic net loss per share $ (17.93 ) $ (9.41 ) $ (18.79 )

Diluted net loss per share (Note 2) $ (17.93 ) $ (14.00 ) $ (18.79 )

The accompanying notes are an integral part of these consolidated financial statements.

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Karyopharm Therapeutics Inc.

Consolidated Statements of Comprehensive Loss

(in thousands)

For the Years Ended December 31,

Other comprehensive (loss) income

Unrealized (loss) gain on investments (62 ) 133 278

Foreign currency translation adjustment 489 (328 ) 199

The accompanying notes are an integral part of these consolidated financial statements.

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Karyopharm Therapeutics Inc.

Consolidated Statements of Stockholders’ Deficit

(in thousands)

Shares Amount

Vesting of restricted stock 70 — — — — —

Stock-based compensation expense — — 21,709 — — 21,709

Issuance of common stock warrants — — 239 — — 239

Unrealized gain on investments — — — 278 — 278

Foreign currency cumulative translation adjustment — — — 199 — 199

Vesting of restricted stock 162 — — — — —

Shares issued under the employee stock purchase plan 132 — 1,452 — — 1,452

Issuance of common stock for financial advisory fee 458 1 6,927 — — 6,928

Stock-based compensation expense — — 18,426 — — 18,426

Unrealized gain on investments — — — 133 — 133

Foreign currency cumulative translation adjustment — — — (328 ) — (328 )

Vesting of restricted stock 229 — — — — —

Shares issued under the employee stock purchase plan 146 — 761 — — 761

Shares issued upon exercise of pre-funded warrants 2,299 — — — — —

Stock-based compensation expense — — 14,050 — — 14,050

Unrealized loss on investments — — — (62 ) — (62 )

Foreign currency cumulative translation adjustment — — — 489 — 489

The accompanying notes are an integral part of these consolidated financial statements.

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Karyopharm Therapeutics Inc.

Consolidated Statements of Cash Flows

(in thousands)

For the Years Ended December 31,

Operating activities

Adjustments to reconcile net loss to net cash used in operating activities:

Amortization of debt issuance costs and discounts 10,546 6,369 814

Interest expense added to debt principal 6,258 — —

Loss (gain) on extinguishment of debt 62,365 (44,702 ) —

Changes in operating assets and liabilities:

Investing activities

Purchases of property and equipment — (142 ) —

Financing activities

Proceeds from convertible debt 15,000 — —

Proceeds from senior secured term loan 12,250 83,300 —

Payment of convertible debt (250 ) — —

Payment of deferred royalty obligation — (40,518 ) —

Payment of debt and equity issuance costs (6,463 ) (2,588 ) —

Short-term restricted cash — — 660

Supplemental disclosures:

Cash paid for interest on deferred royalty obligation $ 3,711 $ 21,475 $ 16,053

Lease liabilities arising from obtaining right-of-use assets $ — $ 3,602 $ —

Debt issued for interest payments $ 12,822 $ — $ —

The accompanying notes are an integral part of these consolidated financial statements.

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Karyopharm Therapeutics Inc.

Notes to Consolidated Financial Statements

1. Organization and Operations

We are a commercial-stage pharmaceutical company pioneering novel cancer therapies and dedicated to the discovery, development and commercialization of first-in-class drugs directed against nuclear export for the treatment of cancer. Our scientific expertise is based upon an understanding of the regulation of intracellular communication between the nucleus and the cytoplasm. We have discovered and are developing and commercializing novel, small molecule XPO1 inhibitor compounds that inhibit the nuclear export protein exportin 1. Our primary focus is on marketing XPOVIO® (selinexor) in its currently approved indications, as well as developing and seeking the regulatory approval of selinexor as an oral agent targeting multiple high unmet cancer indications, including our lead clinical programs in myelofibrosis and endometrial cancer and our other late-stage clinical program in multiple myeloma. We were incorporated in Delaware on December 22, 2008 and have a principal place of business in Newton, Massachusetts.

Our lead asset, XPOVIO, received its initial U.S. approval from the U.S. Food and Drug Administration (the “FDA”) in July 2019 and is currently approved and marketed for the following indications: (i) in combination with bortezomib and dexamethasone for the treatment of adult patients with multiple myeloma who have received at least one prior therapy; (ii) in combination with dexamethasone for the treatment of adult patients with relapsed or refractory multiple myeloma who have received at least four prior therapies and whose disease is refractory to at least two proteasome inhibitors, at least two immunomodulatory agents, and an anti-CD38 monoclonal antibody; and (iii) for the treatment of adult patients with relapsed or refractory diffuse large B-cell lymphoma (“DLBCL”), not otherwise specified, including DLBCL arising from follicular lymphoma, after at least two lines of systemic therapy. The commercialization of XPOVIO and NEXPOVIO® (selinexor) (the brand name for selinexor in Europe and the United Kingdom) outside of the U.S. is managed by our partners in their respective territories. XPOVIO/NEXPOVIO has received regulatory approval in various indications in 50 territories and countries outside the U.S. and is commercially available in a growing number of countries as our partners continue to secure reimbursement approvals.

We have historically financed our operations primarily through a combination of proceeds from (i) product revenue sales; (ii) public and private placements of equity securities; (iii) the issuance of convertible debt; (iv) a term loan; (v) our deferred royalty obligation; (vi) at the market offerings; and (vii) business development activities. As of December 31, 2025, we had $63.7 million of cash, cash equivalents and investments and an accumulated deficit of $1.8 billion. We have incurred significant operating losses since our inception and we anticipate that we will continue to incur significant operating losses to maintain our research and development programs, including as we continue to develop and seek regulatory approval of selinexor for multiple cancer indications, and to support our continued operations. As a result, our continued operations are dependent on our ability to raise additional funding or enter in other strategic alternatives and marketing XPOVIO in its currently approved indications. Based on our current business plan and current capital resources, given the uncertainty regarding the availability of additional funding or other strategic alternatives and considering our debt service obligations and financial covenant to maintain minimum liquidity, we have concluded that there is substantial doubt regarding our ability to continue as a going concern within one year after the date the accompanying consolidated financial statements are issued. We plan to address the conditions that raise substantial doubt regarding our ability to continue as a going concern by, among other things, obtaining additional funding through equity offerings, debt financings and refinancings, collaborations, strategic alliances and/or licensing arrangements. However, there is no assurance that these efforts will result in additional funding, strategic alliances or licensing arrangements or sufficiently address the Company’s ability to continue as a going concern.

If we utilize our capital resources more quickly than anticipated or are unable to obtain additional funding or engage in strategic alternatives, we may have to significantly curtail, delay, reduce or eliminate one or more of our research and development programs or any current or future commercialization efforts for one or more of our products or product candidates, which could materially adversely affect our business, financial condition, and results of operations. We may determine to take additional actions to reduce our spending in the near term. As we announced in July 2025, we reduced our workforce by approximately 20% as part of our ongoing careful management of operating expenses. If we are unable to continue as a going concern, we may have to liquidate assets and may receive less than the value at which those assets are carried on our financial statements. We may also determine to cease operations or file for bankruptcy protection. In any of these circumstances, it is likely that investors will lose all or part of their investment. If there remains substantial doubt about our ability to continue as a going concern, investors or other financing sources may be unwilling to provide funding to us on commercially reasonable terms, if at all. The accompanying consolidated financial statements do not include any adjustments to the carrying amounts and classification of assets and liabilities that may be necessary if we were unable to continue as a going concern.

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2. Summary of Significant Accounting Policies

Basis of Presentation and Principles of Consolidation

The accompanying consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”) and include the accounts of (i) Karyopharm Therapeutics Inc., (ii) Karyopharm Securities Corp. (“KSC”), our wholly-owned Massachusetts corporation incorporated in December 2013 and dissolved in October 2024, (iii) Karyopharm Europe GmbH, our wholly-owned German limited liability company, incorporated in September 2014, and (iv) Karyopharm Israel Ltd., our wholly-owned Israeli subsidiary formed in June 2018. All intercompany balances and transactions have been eliminated in consolidation.

On February 25, 2025, we effected a 1-for-15 reverse stock split of our common stock (the “Reverse Stock Split”). All share and per share amounts in these consolidated financial statements and notes thereto, including the conversion rates of convertible debt and the exercise price of common stock warrants, have been adjusted retroactively to reflect the Reverse Stock Split for all periods presented.

Recent Accounting Pronouncements

In December 2023, the Financial Accounting Standards Board issued Accounting Standards Update 2023-09, Improvements to Income Tax Disclosures, which requires entities to disclose additional information about their effective tax rate reconciliation. We adopted this standard on a prospective basis beginning with the year ended December 31, 2025. The adoption of this standard had no material impact on our financial statements and resulted only in expanded income tax disclosure requirements.

In November 2024, the Financial Accounting Standards Board issued Accounting Standards Update 2024-03, Reporting Comprehensive Income - Expense Disaggregation Disclosures. This standard requires disclosure of specified information about certain costs and expenses including purchases of inventory and employee compensation. This standard also requires disclosure of the total amount of selling expenses, and, in annual reporting periods, the Company’s definition of selling expenses. This standard is effective for fiscal years beginning after December 15, 2026, and interim periods within fiscal years beginning after December 15, 2027. Early adoption is permitted. We are evaluating the impact of this standard and expect its effect to be limited to enhanced disclosures in the notes to the consolidated financial statements.

Segment Information

Operating segments are defined as components of an enterprise whose operating results are regularly reviewed by the Chief Operating Decision Maker (“CODM”) to allocate resources and assess performance. We view our operations and manage our business as a single operating segment, which is the business of discovering, developing and commercializing drugs to treat cancer. All our revenue and all our long-lived assets are attributable to our single operating segment and to Karyopharm Therapeutics Inc., which is domiciled in the United States.

Our CODM is our Chief Executive Officer who uses net loss as reported on the consolidated statements of operations to monitor budget versus actual results and to ensure we have sufficient capital resources to develop and seek regulatory approval of our product candidates.The following table presents the significant revenue and expense categories (in thousands) in our single operating segment:

For the Years Ended December 31,

(1) Excludes stock-based compensation expense

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Use of Estimates

The preparation of financial statements in conformity with U.S. GAAP requires management 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 and the reported amounts of revenues and expenses during the reporting period.

On an ongoing basis, we evaluate our estimates, including estimates related to our net product revenue, license and other revenue, clinical trial accruals, stock-based compensation expense, interest expense on our deferred royalty obligation, embedded derivative liabilities, liability-classified common stock warrants, valuation allowances, and other reported amounts of expenses during the reported period. We base our estimates on historical experience and other market-specific or relevant assumptions that we believe to be reasonable under the circumstances. Although we regularly assess these estimates, actual results could differ from those estimates. Changes in estimates are recorded in the period in which they become known.

Concentrations of Credit Risk and Off-Balance Sheet Risk

Financial instruments which potentially subject us to credit risk consist primarily of cash, cash equivalents and investments. We hold these investments in highly rated financial institutions, and, by policy, limit the amounts of credit exposure to any one financial institution. These amounts at times may exceed federally insured limits. We have not experienced any credit losses in such accounts and do not believe we are exposed to any significant credit risk on these funds. We have no off-balance sheet concentrations of credit risk.

The following table summarizes customers that represent 10% or greater of our consolidated total revenue:

For the Years Ended December 31,

The following table summarizes customers with amounts due that represent 10% or greater of our consolidated accounts receivable, net balance:

As of December 31,

Fair Value Measurements

Fair value is the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. We disclose information on all assets and liabilities reported at fair value that enables an assessment of the inputs used in determining the reported fair values. The fair value hierarchy prioritizes valuation inputs based on the observable nature of those inputs. The fair value hierarchy applies only to the valuation inputs used in determining the reported fair value and is not a measure of credit quality. The hierarchy defines three levels of valuation inputs:

Level 1 inputs: Quoted prices in active markets for identical assets or liabilities

Level 2 inputs: Inputs other than quoted prices included within Level 1 that are observable for the asset or liability, either directly or indirectly

Level 3 inputs: Unobservable inputs that reflect our own assumptions about the assumptions market participants would use in pricing the asset or liability.

Cash and Cash Equivalents

Cash and cash equivalents consist primarily of demand deposit accounts and deposits in short-term money market funds. Cash equivalents are stated at cost, which approximates fair value. We consider all highly liquid investments with maturities of three

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months or less from the date of purchase to be cash equivalents. We do not hold any money market funds with significant liquidity restrictions that would be required to be excluded from cash equivalents.

Investments

We determine the appropriate classification of our investments at the time of purchase. All of our investments are reported as short-term as they are available for use during the normal cycle of business. We review any investment when its fair value is less than its amortized cost and when evidence indicates that the investment’s carrying amount is not recoverable within a reasonable period. We evaluate whether the decline in fair value has resulted from credit losses or other factors. In making this assessment, we consider the extent to which fair value is less than amortized cost, any changes to the rating of the security by a rating agency, and adverse conditions specifically related to the security, among other factors. If this assessment indicates that a credit loss exists and if the present value of cash flows expected to be collected is less than the amortized cost basis, an allowance is recorded on our consolidated balance sheet, limited by the amount that the fair value is less than the amortized cost basis. Any impairment that is not related to a credit loss is recognized in other comprehensive (loss) income.

Changes in the allowance for credit losses are recorded as a provision for (or reversal of) credit loss expense. Losses are charged against the allowance when we believe the uncollectability of an investment is confirmed or when either of the criteria regarding intent or requirement to sell is met.

Accounts Receivable

Amounts are recorded as accounts receivable when our right to consideration is unconditional other than the passage of time. Accounts receivable consists of amounts due from customers, net of customer allowances for cash discounts and chargebacks. Our contracts with customers have standard payment terms that generally require payment within 30 to 68 days. We analyze accounts for collectability and periodically evaluate the creditworthiness of our customers. We determined an allowance for credit losses was not material as of December 31, 2025 and 2024 as we have had no bad debt write-offs to date and we did not have credit issues with any customers as of December 31, 2025.

Accrued Research and Development Costs

We estimate our accrued research and development costs by reviewing quotes and contracts, identifying services that have been performed on our behalf, and estimating the associated cost incurred for services performed when we have not yet been invoiced or otherwise notified of the actual cost. Most of our service providers invoice us monthly in arrears for services performed or when contractual milestones are met. We make estimates of our accrued research and development costs at each balance sheet date in our financial statements based on facts and circumstances known to us at that time. We periodically confirm the accuracy of our estimates with the service providers and make adjustments if necessary. The significant estimates in our accrued research and development costs include fees incurred with contract research organizations (“CROs”) in connection with research and development activities as well as fees to be paid to investigative sites in connection with clinical studies, for which we have not yet been invoiced.

We base our expenses related to CROs on our estimates of the services performed and efforts expended pursuant to quotes and contracts with CROs that conduct research and development activities on our behalf. The payment terms of these agreements are subject to negotiation, vary from contract to contract and may result in uneven payment flows. There may be instances in which payments made to our service providers will exceed the level of services performed and result in a prepayment. In accruing service fees, we estimate the time period over which the services will be performed and the level of effort to be expended in each period. If the actual timing of the performance of services or the level of effort varies from our estimates, we adjust the accrual or prepayment accordingly. Although we do not expect our estimates to be materially different from amounts actually incurred, if our estimates of the status and timing of services performed differ from the actual status and timing of services performed, it could result in us reporting amounts that are too high or too low in any particular period. To date, our estimates have not been materially different than amounts actually incurred.

Deferred Royalty Obligation

The deferred royalty obligation, as discussed further in Note 10, “Long-Term Obligations”, is amortized using the effective interest rate method over the estimated life of the revenue streams. We recognize interest expense thereon using the effective rate, which is based on our current estimates of future revenues over the life of the arrangement. We periodically assess our expected revenues using internal projections, impute interest on the carrying value of the deferred royalty obligation, and record interest expense using the imputed effective interest rate. To the extent our estimates of future revenues are greater or less than previous estimates or the estimated timing of such payments is materially different than previous estimates, we will account for any such

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changes by adjusting the effective interest rate on a prospective basis, which will adjust future interest expense with a corresponding impact to the classification of our deferred royalty obligation. The assumptions used in determining the expected repayment term of the deferred royalty obligation and amortization period of the issuance costs requires that we make estimates that could impact the short-term and long-term classification of such costs, as well as the period over which such costs will be amortized.

Embedded Derivatives

Embedded derivatives that require bifurcation are separated from the host debt instrument and are measured at fair value at the end of each reporting period. See Note 6, “Fair Value Measurements”, for additional detail on the valuation methodology. Changes in fair value are recognized as a component of other income (expense), net on our consolidated statements of operations. Embedded derivatives are reported in the same line as the host debt instrument on the consolidated balance sheets.

Common Stock Warrants

We classify our common stock warrants, including pre-funded warrants, in stockholder’s deficit if they allow for settlement only in shares of our common stock, are indexed to our common stock, and meet the criteria for equity classification. Common stock warrants that do not meet the criteria for equity classification are classified as liabilities and are measured at fair value at the end of each reporting period. See Note 6, “Fair Value Measurements”, for additional detail on the valuation methodology.

Revenue Recognition

To determine revenue recognition, we perform 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) we satisfy a performance obligation. At contract inception, we assess whether the goods or services promised within a contract with a customer are distinct and, therefore, represent a separate performance obligation. Goods or services that are determined not to be distinct are combined with other promised goods and services until a distinct bundle is identified. We then determine the transaction price, which is the total amount of consideration we expect to receive from a customer in exchange for the promised goods or services and includes an estimate of any variable consideration in the contract. We then allocate the transaction price to each performance obligation and recognize the associated revenue when (or as) our customer obtains control of the goods or services within the performance obligation.

Incremental costs of obtaining a contract with a customer are capitalized and amortized consistent with the pattern of transferring the goods or services to which the cost relates when the expected amortization period of the asset is greater than one year. Incremental costs are expensed as incurred if the expected amortization period of the asset that we would have recognized is one year or less.

Product Revenue Recognition

We ship XPOVIO in the U.S. to specialty pharmacies and specialty distributors, collectively referred to as our customers, under a limited number of distribution arrangements with such third parties. Our specialty pharmacy customers resell XPOVIO directly to patients, while our specialty distributor customers resell XPOVIO to healthcare entities, who then resell XPOVIO to patients. We also enter into certain arrangements with group purchasing organizations and/or other payors that provide for government mandated and/or privately negotiated rebates, chargebacks, and discounts with respect to the purchase of our products.

Each unit of XPOVIO that is ordered by our customers represents a distinct performance obligation that is completed when control of the product is transferred to the customer. Accordingly, we recognize product revenue when the customer obtains control of our product, which occurs at a point in time, upon delivery pursuant to our agreements with our customers. If taxes are collected from customers relating to product sales and remitted to governmental authorities, they are excluded from revenue.

Revenue from product sales is recorded at the net sales price, which includes estimates of variable consideration for which reserves are reported. These reserves, as detailed below, are based on the amounts earned, or to be claimed on the related sales, and are generally classified as reductions of accounts receivable (if the amount is payable to the customer) or a current liability (if the amount is payable to a party other than a customer). Certain amounts are known at the time of sale based on contractual terms and are recorded pursuant to the most likely amount method, which is the single most likely amount in a range of possible considerations.

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The following are the components of variable consideration related to product revenue:

Cash discounts and distributor fees: We provide customary discounts on XPOVIO sales to our customers for prompt payment, the terms of which are explicitly stated in our contracts with such customers. We also pay fees to our customers for sales order management, data, and distribution services, the terms of which are also explicitly stated in our contracts with such customers. Such fees are not for a distinct good or service and, accordingly, are recorded as a reduction of revenue, as well as a reduction to accounts receivable (cash discounts) or as a component of accrued expenses (distributor fees).

Product returns: Consistent with industry practice, we offer our customers and other indirect purchasers a limited right of return for purchased units of XPOVIO for damage, defect, recall, and/or product expiry (beginning three months prior to the product’s expiration date and ending six to twelve months after the product’s expiration date). We estimate the amount of product sales that will be returned using quantitative and qualitative considerations, such as visibility into the inventory remaining in the distribution channel and historical returns data. Reserves for estimated returns are recorded as a reduction of revenue in the period that the related revenue is recognized, as well as a component of accrued expenses. We update our estimated return liability each reporting period based on actual shipments of XPOVIO subject to contractual return rights, changes in expectations about the amount of estimated and/or actual returns, and other qualitative considerations.

Chargebacks: Chargebacks for fees and discounts represent the estimated obligations resulting from our contractual commitments to provide products to qualified healthcare entities at prices lower than the list prices charged to our customers who purchase XPOVIO directly from us. Our customers charge us for the discount provided to the healthcare entities. Chargebacks are generally determined at the time of resale to the qualified healthcare provider by our customers. Accordingly, reserves for chargebacks consist of credits that we expect to issue for units that remain in the distribution channel inventory at the end of the reporting period that we expect will be sold to qualified healthcare entities, as well as chargebacks that customers have claimed, but for which we have not yet issued a credit. We record reserves for chargebacks based on contractual terms in the same period that the related revenue is recognized, resulting in a reduction of product revenue and accounts receivable. We generally issue credits to the customer for such amounts within a few weeks after the customer notifies us of the resale to a discount-eligible healthcare entity.

Government rebates: We are subject to discount obligations under state Medicaid programs, Medicare, the Department of Veterans Affairs, the Department of Defense, and others. These reserves are recorded in the same period the related revenue is recognized, resulting in a reduction of product revenue and the establishment of a current or long-term liability. Current liabilities are included as a component of accrued expenses and long-term liabilities are included as a component of other liabilities on the consolidated balance sheets. For Medicare, we estimate the number of patients in the prescription drug coverage gap for whom we will owe an additional liability under Medicare Part D. Our liability for these rebates consists of invoices received for claims from prior and current quarters that have not been paid or for which an invoice has not yet been received, estimates of claims for the current quarter, and estimated future claims that will be made for product that has been recognized as revenue, but which remains in distribution channel inventories at the end of the reporting period.

Other incentives: Other incentives offered by us include co-payment assistance, which we provide as financial assistance to patients with commercial insurance that requires prescription drug co-payments by the patient. We calculate the accrual for co-payment assistance based on estimates of claims and the average co-payment assistance amounts per claim that we expect to receive associated with sales of XPOVIO that have been recognized as revenue but remain in distribution channel inventories at the end of the reporting period. Such estimates are based on industry experience with similar products, as well as actual amounts from our product sales to date. Any adjustments to such estimated liabilities on units in the distribution channel at period end, as well as actual amounts incurred on units sold through the distribution channel during the period, are recorded in the same period that the related revenue is recognized, resulting in a reduction of product revenue and the establishment of a current liability, which is included as a component of accrued expenses.

Product revenue reserves and allowances: As noted above, cash discounts and chargebacks are recorded as reductions of accounts receivable and product returns, distributor fees, government rebates, and other incentives are recorded as a component of accrued expenses. Actual amounts of consideration ultimately received may differ from our estimates. If actual results in the future vary from our estimates, we will adjust these estimates, which would affect product revenue, net and earnings in the period in which such variances become known.

License Agreements

We generate revenue from license or similar agreements with pharmaceutical companies for the development and commercialization of certain of our products and product candidates. Such agreements may include the transfer of intellectual property rights in the form of licenses, transfer of technological know-how, delivery of drug substances, research and development services,

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and participation on certain committees with the counterparty. Payments made by the customer may include non-refundable upfront fees, payments upon the exercise of options, payments based upon the achievement of defined milestones, and royalties on sales of products and product candidates if they are approved and commercialized. Our license agreements are detailed in Note 5, “License Agreements”.

At contract inception, we evaluate all goods or services in the agreement to determine if they are distinct. If they are not distinct, they are combined with other promised goods or services to create a bundle of promised goods or services that are distinct. Distinct goods or services and distinct bundles of goods or services are considered performance obligations. Optional future services where any additional consideration paid to us reflects their standalone selling prices do not provide the customer with a material right and, therefore, are not considered performance obligations. Optional future services that are priced in a manner which provides the customer with a significant or incremental discount are considered performance obligations because they provide the customer with a material right.

We utilize judgment to estimate the transaction price at contract inception. We evaluate contingent milestones to determine if they should be included in the transaction price using the most likely amount method. Milestone payments that are not within our control, such as regulatory approvals, are not considered likely of being achieved until those approvals are received and are excluded from the transaction price using the most likely amount method. The transaction price is then allocated to each performance obligation on a relative standalone selling price basis, for which we recognize revenue as or when the performance obligations are satisfied. At the end of each reporting period, we re-evaluate our estimate of the transaction price, including the probability of achieving milestone payments that may not be subject to a material reversal, and adjust the transaction price if necessary. Any such adjustments are recorded on a cumulative catch-up basis, which would affect license and other revenue in the period of adjustment.

We then determine whether the performance obligations are satisfied over time or at a point in time and, if over time, the appropriate method of measuring progress for purposes of recognizing revenue. We evaluate the measure of progress, as applicable, for each reporting period and, if necessary, adjust the measure of performance and related revenue recognition.

When consideration is received, or such consideration is unconditionally due, from a customer prior to transferring goods or services to the customer under the terms of a contract, a contract liability is recorded within deferred revenue. Contract liabilities within deferred revenue are recognized as revenue after control of the goods or services is transferred to the customer and all revenue recognition criteria have been met.

For arrangements that include a license of intellectual property and sales-based royalties, including sales-based milestone payments, we recognize revenue when the related sales occur because the license of intellectual property is deemed to be the predominant item to which the royalties relate.

Research and Development Expenses

Research and development costs are charged to expense as incurred and include, but are not limited to:

•

employee-related expenses, including salaries, benefits, travel and stock-based compensation expense;

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expenses incurred under agreements with CROs, CMOs and consultants that help conduct clinical trials and preclinical studies;

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the cost of acquiring, developing and manufacturing clinical trial materials, including comparator products;

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facilities, depreciation and other expenses, which include direct and allocated expenses for rent and maintenance of facilities, insurance and other supplies; and

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costs associated with preclinical activities and regulatory operations.

Costs for certain research and development activities, such as clinical trials, are recognized based on various inputs, including an evaluation of the progress to completion of specific tasks using data such as patient enrollment, clinical site activations, and other information provided to us by our vendors based on their actual costs incurred. Payments for these activities are based on the terms of the individual arrangements, which may differ from the pattern of costs incurred, and are accordingly reflected in our financial statements as prepaid or accrued research and development costs.

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Selling, General and Administrative Expenses

Selling, general and administrative costs are charged to expense as incurred and consist primarily of salaries, benefits, travel, and other related costs, including stock-based compensation, for personnel in executive, finance, commercial and administrative functions. Other significant costs include facility costs not otherwise included in research and development expenses, legal fees relating to patent and corporate matters and fees for accounting and consulting services.

Accounting for Stock-Based Compensation

We grant stock-based awards to employees and non-employees, including stock options, restricted stock units (“RSUs”), performance-based restricted stock units (“PSUs”) and shares issued under our employee stock purchase plan (“ESPP”). We account for all stock-based awards at their fair value as of the grant date and recognize compensation expense on the consolidated statements of operations on a straight-line basis over the vesting period of the award. We use the Black-Scholes option pricing model to determine the fair value of stock options as of the grant date. The fair value of RSUs is the quoted closing market price per share of our common stock on the Nasdaq Global Select Market on the grant date. Forfeitures are recognized as they occur.

PSUs are awards which will vest if certain performance goals are achieved over a certain performance period. Certain portions of certain PSU awards vest based on continuous service to the Company throughout the performance period even if the performance goal is not achieved. Stock-based compensation expense for PSUs is determined using the grant date fair value, which is the quoted closing market price per share of our common stock on the Nasdaq Global Select Market on the grant date. The grant date fair value of PSUs with a market condition also includes a discount that represents the likelihood that the related performance goals will not be achieved. Stock-based compensation expense for PSUs with a market condition is recognized on a straight-line basis over the service period. Market conditions include goals related to the performance of our common stock. Stock-based compensation expense for PSUs without a market condition is not recognized until the achievement of the performance goal is deemed probable (the “Probable Date”). At the Probable Date, we record a cumulative catch-up expense for the portion of the grant date fair value attributable to the period from the grant date to the Probable Date. The remaining expense is recognized over the remaining service period on a straight-line basis.

Foreign Currency Transactions

The functional currency of our subsidiaries in Germany and Israel are the Euro and Shekel, respectively. Foreign currency transaction gains and losses are recorded on the consolidated statements of operations and were immaterial for the years ended December 31, 2025, 2024 and 2023.

Income Taxes

We use the liability method of accounting for income taxes. Under this method, deferred tax assets and liabilities are determined based on the difference between the financial reporting and the tax reporting basis of assets and liabilities and are measured using the enacted tax rates and laws that are expected to be in effect when the differences are expected to reverse. We provide a valuation allowance against deferred tax assets unless, based upon the available evidence, it is more likely than not that the deferred tax assets will be realized. We have evaluated available evidence and concluded that we may not realize the benefit of our deferred tax assets; therefore, a valuation allowance has been established for the full amount of the net deferred tax assets. We recognize interest and/or penalties related to income tax matters in income tax expense. Our state tax provision pertains to income generated by our KSC entity. Our foreign tax provision pertains to foreign income taxes due by our German and Israel subsidiaries, both of which operate on a cost-plus profit margin basis.

Net Loss Per Share

Basic net loss per common share is calculated using the two-class method by dividing the net loss allocated to common shares by the weighted-average number of common shares outstanding for the period, which includes the common shares deliverable upon the exercise of outstanding pre-funded warrants. Diluted net loss per common share is calculated by adjusting net loss to remove the effects from potential dilutive common shares and dividing this adjusted amount by the weighted average number of common shares and potential dilutive common shares outstanding for the period. Potential dilutive common shares are not included if their effect is anti-dilutive.

As discussed further in Note 10, “Long-Term Obligations”, the conversion obligation for our 3.00% unsecured convertible senior notes due 2025 (the “2025 Notes”) could have been settled in common shares. The 2025 Notes did not impact the calculation of dilutive loss per common share during the year ended December 31, 2023 because they were anti-dilutive in that period. The table below describes the impact of the 2025 Notes on the calculation of dilutive loss per common share during the year ended December

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31, 2024. No 2025 Notes were outstanding as of December 31, 2025.

As discussed further in Note 10, “Long-Term Obligations”, the conversion obligations for our: (i) 6.00% senior secured convertible notes due 2029 (the “2029 Notes”), (ii) 9.00% senior secured convertible notes due 2029 (the “New 2029 Notes”), and (iii) 9.00% senior secured convertible notes due 2028 (the “2028 Notes”) can potentially be settled in common shares. The 2029 Notes, New 2029 Notes, and 2028 Notes did not impact the calculation of dilutive loss per common share during the years ended December 31, 2025, 2024, and 2023 because they either did not exist or were anti-dilutive during these periods.

As discussed further in Note 11, “Common Share Warrants”, warrants to purchase common shares were outstanding as of December 31, 2025, 2024 and 2023. All outstanding warrants, except pre-funded warrants, are not included in the calculation of basic net loss per share because the warrant holders do not have an obligation to share in our losses, and these warrants did not impact the calculation of dilutive loss per common share during the years ended December 31, 2025, 2024 and 2023 because they either did not exist or were anti-dilutive during these periods. Pre-funded warrants are included in the calculation of basic and diluted net loss per share due to their de-minimus exercise price.

Diluted net loss per common share was equal to basic net loss per common share for the years ended December 31, 2025 and 2023. The following is a reconciliation of the numerator and denominator used to calculate diluted net loss per common share for the year ended December 31, 2024 (in thousands except per share amounts):

For the Year Ended December 31, 2024

Add back interest expense on the 2025 Notes 2,736

Add back gain on extinguishment of debt (44,702 )

Numerator for diluted net loss per common share (A) $ (118,388 )

Weighted-average number of common shares outstanding 8,125

Dilutive effect of 2025 Notes calculated using the if-converted method 330

Denominator for diluted net loss per common share (B) 8,455

Diluted net loss per common share (= A / B) $ (14.00 )

The following potentially dilutive securities were excluded from the calculation of diluted net loss per share due to their anti-dilutive effect (in thousands):

As of December 31,

Common shares deliverable upon conversion of 2025 Notes — — 725

Common shares deliverable upon conversion of 2028 Notes 2,305 — —

Common shares deliverable upon conversion of 2029 Notes 4,693 3,436 —

Outstanding common stock warrants, except pre-funded warrants 9,622 3,704 652

Comprehensive Loss

Comprehensive loss consists of net loss and certain changes in stockholders’ deficit that are excluded from net loss, which currently consists of unrealized gains and losses on investments and foreign currency translation adjustments.

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3. Product Revenue

To date, our only source of product revenue has been from the U.S. sales of XPOVIO. The following table summarizes activity in each of the product revenue allowance and reserve categories (in thousands):

Discounts andChargebacks Fees, Rebates,and OtherIncentives Returns Total

Provision related to sales in the prior year — 1,305 4,519 5,824

Discounts and chargebacks are recorded as reductions of accounts receivable, and returns, fees, rebates, and other incentives are recorded as a component of accrued expenses and other liabilities.

As of December 31, 2025 and 2024, net product revenue of $22.7 million and $27.8 million, respectively, was included in accounts receivable, net.

4. Inventory

Prior to regulatory approval, we expense costs relating to the production of inventory as research and development expenses in the period incurred. We capitalize the costs incurred to manufacture our products after regulatory approval when, based on our judgment, future commercialization is considered probable and the future economic benefit is expected to be realized. We value our inventories at the lower of cost or estimated net realizable value. We determine the cost of our inventories, which includes amounts related to materials and manufacturing overhead, on a first-in, first-out basis. Raw materials and work in process includes all inventory costs prior to packaging and labeling, including raw materials, active pharmaceutical ingredient, and drug product. Finished goods include packaged and labeled products.

Raw materials and work in process that may be used for either research and development or commercial sale are classified as inventory until the material is consumed or otherwise allocated for research and development. If the material is intended to be used for research and development, it is expensed as research and development once that determination is made.

We assess the recoverability of our inventory each reporting period and write-down any inventory that has become obsolete, that has a cost basis in excess of its estimated realizable value, or that is not expected to be sold or otherwise consumed before expiry. Inventory write-downs are recorded as cost of sales in the period the impairment is identified.

Cost of sales includes the cost of producing and distributing inventories related to sales of XPOVIO in the U.S. and sales of selinexor to our partners who commercialize our products outside of the U.S. Cost of sales is recognized in the period the related sales occur and includes compensation expense for employees involved with production and distribution, freight, and indirect overhead costs, as well as third-party royalties payable on net product revenue. Cost of sales may also include excess or obsolete inventory adjustment charges, abnormal costs, unabsorbed manufacturing and overhead costs, and manufacturing variances.

The following table presents our inventory (in thousands), all of which was related to XPOVIO:

As of December 31,

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5. License Agreements

The following license agreements affected the consolidated financial statements during the years ended December 31, 2025, 2024 and 2023:

Menarini License Agreement

In December 2021, we entered into a license agreement (the “Original Menarini Agreement”) with Berlin-Chemie AG, an affiliate of the Menarini Group (“Menarini”), pursuant to which we granted Menarini a non-exclusive license to develop, and an exclusive license to commercialize, products containing selinexor (the “Product”), for all human oncology indications in the European Economic Area, United Kingdom, Switzerland, Armenia, Azerbaijan, Belarus, Kazakhstan, Kyrgyzstan, Moldova, Russia, Tajikistan, Turkmenistan, Uzbekistan, Ukraine, Turkey, Mexico, all Central America countries and all South America countries (collectively, the “Menarini Territory”). In March 2023, the Original Menarini Agreement was amended (the “Amended Menarini Agreement”) to expand the Menarini Territory to include all countries in the continent of Africa and Saudi Arabia, United Arab Emirates, Kuwait, Oman, Qatar, Bahrain, Lebanon, Jordan, Iraq, and Yemen (together with the Menarini Territory, the “Expanded Menarini Territory”). In addition, we granted to Menarini a non-exclusive license to package and label the Product in or outside of the Expanded Menarini Territory for all human oncology indications solely to enable Menarini to commercialize the Product within the Expanded Menarini Territory.

Under the terms of the Amended Menarini Agreement, we will use commercially reasonable efforts to develop the Product, transfer any marketing approval or authorization with respect to the Product in the Expanded Menarini Territory to Menarini and to complete any post-marketing approval or authorization studies required by a regulatory authority as a condition of maintaining the approval in any country in the Expanded Menarini Territory. Menarini is obligated to use commercially reasonable efforts to apply for and obtain marketing approval or authorization of the Product, and to obtain price or reimbursement approval for the Product after approval of the relevant marketing approval or authorization, in each country of the Expanded Menarini Territory in each indication for which we have conducted a registrational clinical trial. Menarini is also obligated to use commercially reasonable efforts at its sole cost and expense to launch and commercialize the Product in each country of the Expanded Menarini Territory in each indication for which we have conducted a registrational clinical trial.

We received an upfront cash payment of $75.0 million in December 2021 under the Original Menarini Agreement and $3.5 million in April 2023 upon execution of the Amended Menarini Agreement. In addition, we have received and are entitled to receive additional milestone payments from Menarini if certain development and sales performance milestones are achieved. We have received and are further eligible to receive tiered royalties ranging from the mid-teens to mid-twenties based on future net sales of the Product in the Expanded Menarini Territory. The payments owed by Menarini to us are subject to reduction in specified circumstances. Menarini also reimbursed us $15.0 million per calendar year, or $60 million in total, for development related expenses we incurred for selinexor from 2022 through 2025.

The Amended Menarini Agreement will continue in effect on a country-by-country basis until the last to occur among: (i) the fifteenth anniversary of the first commercial sale of the Product in the applicable country, (ii) the expiration of the last-to-expire of the licensed patent rights in the applicable country or (iii) the expiration of any regulatory exclusivity protection covering the Product in such country. However, the Amended Menarini Agreement may be terminated earlier by either party for (i) an uncured material breach of the Amended Menarini Agreement by the other party (A) on a country-by-country basis with respect to the country to which the breach does not affect the Amended Menarini Agreement as a whole or (B) in its entirety if the breach affects the Amended Menarini Agreement as a whole, or (ii) in the event of the insolvency or bankruptcy of the other party. We may also terminate the Amended Menarini Agreement for certain patent challenges by Menarini.

We assessed this arrangement and concluded that the contract counterparty, Menarini, is a customer. All development and regulatory milestones, which represent variable consideration, will be evaluated each reporting period and included in the transaction price if the milestone is considered likely of achievement and if it is probable that a significant revenue reversal will not occur in future periods. Milestones included in the transaction price will be fully recognized in revenue in the same reporting period because the distinct performance obligation identified at the inception of the contract was fully satisfied.

Any consideration related to sales-based milestones, as well as royalties on net sales upon commercialization by Menarini, are recognized when the related sales occur, as they were determined to relate predominantly to the intellectual property licenses granted to Menarini.

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Antengene License Agreement

In May 2020, we entered into an amendment to our May 2018 license agreement (the “Original Antengene Agreement” and, as amended, the “Amended Antengene Agreement”) with Antengene Therapeutics Limited, a corporation organized and existing under the laws of Hong Kong (“Antengene”) and a subsidiary of Antengene Corporation Co. Ltd., a corporation organized and existing under the laws of the People’s Republic of China, pursuant to which we expanded the territory licensed to Antengene in the Original Antengene Agreement for the exclusive development and commercialization rights of selinexor, eltanexor and KPT-9274, each for the diagnosis, treatment and/or prevention of all human oncology indications, as well as verdinexor for the diagnosis, treatment and/or prevention of certain human non-oncology indications (“Antengene Licensed Compounds”).

Under the terms of the Amended Antengene Agreement, Antengene has the exclusive development and commercialization rights for the Antengene Licensed Compounds in mainland China, Taiwan, Hong Kong, Macau, South Korea, Brunei, Cambodia, Indonesia, Laos, Malaysia, Myanmar, Philippines, Singapore, Thailand, Vietnam, Australia and New Zealand (the “Antengene Territory”). Under the terms of the Original Antengene Agreement, we received an upfront cash payment of $11.7 million in 2018 and in June 2020 we received a one-time upfront cash payment of $11.7 million in connection with the Amended Antengene Agreement. We have received and are entitled to future milestone payments from Antengene if certain development, regulatory and commercialization goals are achieved. Finally, we have received and are further eligible to receive tiered double-digit royalties based on future net sales of selinexor and eltanexor, and tiered single- to double-digit royalties based on future net sales of verdinexor and KPT-9274 in the Antengene Territory. In addition, upon completion of the manufacturing technology transfer plan, we will grant to Antengene non-exclusive rights to manufacture the Antengene Licensed Compounds solely for their development and commercialization in the Antengene Territory.

As part of the Amended Antengene Agreement, Antengene also has the right to participate in global clinical studies of the Antengene Licensed Compounds and will bear the cost and expense for patients enrolled in such global clinical studies in the Antengene Territory. Antengene is responsible for seeking regulatory and marketing approvals for the Antengene Licensed Compounds in the Antengene Territory, as well as any development of the products necessary to obtain such approvals. Antengene is also responsible for the commercialization of the Antengene Licensed Compounds in the Antengene Territory at its own cost and expense. Until Antengene manufactures its own drug supply, we will furnish clinical and commercial supplies to Antengene pursuant to supply agreements between us and Antengene, the costs of which will be borne by Antengene.

The Amended Antengene Agreement will continue in effect on a product-by-product, country-by-country basis until the later of the tenth anniversary of the first commercial sale of the applicable product in such country or the expiration of specified patent protection and regulatory exclusivity periods for the applicable product in such country. However, the Amended Antengene Agreement may be terminated earlier by (i) either party for breach of the Amended Antengene Agreement by the other party or in the event of the insolvency or bankruptcy of the other party, (ii) Antengene on a product-by-product basis for certain safety reasons or on a product-by-product, country-by-country basis for any reason with 180 days prior notice or (iii) us in the event Antengene challenges or assists with a challenge to certain of our patent rights.

All development and regulatory milestones, which represent variable consideration, will be evaluated each reporting period and included in the transaction price if the milestone is considered likely of achievement and if it is probable that a significant revenue reversal will not occur in future periods. Milestones included in the transaction price will be fully recognized in revenue in the same reporting period because all distinct performance obligations identified at the inception of the contract were fully satisfied.

Any consideration related to sales-based milestones, as well as royalties on net sales upon commercialization of XPOVIO by Antengene, are recognized when the related sales occur, as they were determined to relate predominantly to the intellectual property licenses granted to Antengene.

Summary of License and Other Revenue

The following table presents information about our license and other revenue (in thousands):

For the YearsEnded December 31,

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During the year ended December 31, 2025, we recognized (i) $15.0 million of revenue for the reimbursement of development-related expenses, $8.2 million of milestone revenue, $4.0 million of royalty revenue, and $1.1 million of other reimbursement revenue from Menarini; (ii) $2.1 million of royalty revenue from Antengene; and (iii) $0.4 million of royalty revenue from our other partners.

During the year ended December 31, 2024, we recognized (i) $15.0 million of revenue for the reimbursement of development-related expenses, $10.0 million of milestone revenue, $2.2 million of royalty revenue, and $0.8 million of other reimbursement revenue from Menarini; (ii) $1.7 million of royalty revenue from Antengene; and (iii) $2.0 million of milestone-related revenue, $0.4 million of royalty revenue, and $0.3 million of other reimbursement revenue from our other partners.

During the year ended December 31, 2023, we recognized (i) $15.0 million of revenue for the reimbursement of development related expenses, $4.0 million of milestone-related revenue, $3.5 million of license-related revenue, $1.1 million of royalty revenue, and $0.8 million of other reimbursement revenue from Menarini; (ii) $1.5 million of royalty revenue and $1.2 million of other reimbursement revenue from Antengene; and (iii) $3.4 million of license-related revenue, $2.5 million of milestone-related revenue, $0.5 million of royalty revenue, and $0.5 million of other reimbursement revenue from our other partners.

License and other revenue of $3.5 million and $2.9 million were included in accounts receivable, net as of December 31, 2025 and 2024, respectively.

6. Fair Value Measurements

Financial instruments, including cash, cash equivalents, accounts receivable, net, other current assets, other assets, restricted cash, accounts payable, and accrued expenses, are presented at amounts that approximate fair value as of December 31, 2025 and 2024.

Items classified as Level 2 consist of corporate debt securities, commercial paper, and U.S. government and agency securities. We estimate the fair values of these marketable securities by taking into consideration valuations obtained from third-party pricing sources. These pricing sources utilize industry standard valuation models, including both income and market-based approaches, for which all significant inputs are observable, either directly or indirectly, to estimate fair value. These inputs include market pricing based on real-time trade data for the same or similar securities, issuer credit spreads, benchmark yields, and other observable inputs. We validate the prices provided by our third-party pricing sources by understanding the models used, obtaining market values from other pricing sources and analyzing pricing data in certain instances.

The following tables present information about our financial assets that have been measured at fair value and indicate the fair value hierarchy of the valuation inputs utilized to determine such fair value (in thousands):

Cash equivalents:

U.S. government and agency securities 7,306 — 7,306 —

Investments:

Corporate debt securities 3,204 — 3,204 —

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Cash equivalents:

Investments:

U.S. government and agency securities 3,979 — 3,979 —

In certain cases where there is limited activity or less transparency around inputs to valuation, the related assets or liabilities are classified as Level 3. The following liabilities are measured at fair value at the end of each reporting period, with changes in fair value recognized as a component of other income (expense), net on our consolidated statements of operations. See Note 10, “Long-Term Obligations”, to our consolidated financial statements for further discussion of the following Level 3 liabilities:

(1)

An embedded derivative liability (the “HCRx Derivative”) which is included as a component of the deferred royalty obligation on our consolidated balance sheets. The valuation method for the HCRx Derivative incorporates certain unobservable Level 3 key inputs including: (i) the probability-weighted net sales of XPOVIO and any of our other future products, including worldwide net product sales, upfront payments, milestones and royalties; (ii) our risk-adjusted discount rate; and (iii) the probability of a change in control occurring during the term of the instrument. The HCRx Derivative was deemed to have a de-minimus value as of December 31, 2025 and 2024 primarily due to a $56.2 million decrease in the deferred royalty obligation during the year ended December 31, 2024.

(2)

The embedded derivative liabilities (the “Convertible Notes Derivatives”) associated with the 2029 Notes, New 2029 Notes, and 2028 Notes are included as components of these debt instruments on our consolidated balance sheets. The valuation method for the Convertible Notes Derivatives incorporates certain unobservable Level 3 key inputs including: (i) the volatility of our common stock price and (ii) our estimated credit spread.

(3)

The warrants to purchase up to 3,051,750 shares of our common stock issued in May 2024 (the “2024 Warrants”) are classified as a long-term liability on our consolidated balance sheets. The valuation method for the 2024 Warrants incorporates certain unobservable Level 3 key inputs including: (i) the volatility of our common stock price and (ii) an estimate of when the 2024 Warrants will be exercised based on an option pricing model.

The following table sets forth a summary of the changes in the estimated fair value of the liabilities described above, which are all classified as Level 3 (in thousands):

HCRx Derivative Convertible Notes Derivatives May 2024 Warrants

De-recognition of derivative in 2029 Notes — (7,377 ) —

Initial recognition of derivative in New 2029 Notes — 14,697 —

Initial recognition of derivative in 2028 Notes — 8,793 —

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7. Investments

The following tables summarize our investments in debt securities, classified as available-for-sale (in thousands):

AmortizedCost TotalUnrealizedGains TotalUnrealizedLosses Aggregate Fair Value

Corporate debt securities $ 3,202 $ 2 $ — $ 3,204

AmortizedCost TotalUnrealizedGains TotalUnrealizedLosses Aggregate Fair Value

U.S. government and agency securities 3,978 1 — 3,979

We did not hold any investments that were in an unrealized loss position as of December 31, 2025. We held five investments that were in an unrealized loss position as of December 31, 2024. The unrealized losses were caused by changes to interest rates and did not represent credit losses. We do not intend to sell the investments before recovery of their amortized cost bases, which may be at maturity. All our investments mature within one year from December 31, 2025. The following table summarizes our investments in an unrealized loss position as of December 31, 2024 for which an allowance for credit losses was not recorded, aggregated by major security type and length of time in a continuous unrealized loss position (in thousands):

Less than 12 Months 12 Months or Longer Total

Corporate debt securities $ 4,456 $ (2 ) $ — $ — $ 4,456 $ (2 )

8. Stockholders’ Equity

Reverse Stock Split and Authorized Common Shares

In January 2025, our stockholders approved an amendment to our Restated Certificate of Incorporation, as amended, to increase the number of authorized shares of our capital stock from 405,000,000 shares to 805,000,000 shares and the number of authorized shares of our common stock from 400,000,000 shares to 800,000,000 shares.

In February 2025, we effected a 1-for-15 reverse stock split of the issued and outstanding shares of our common stock as approved by our stockholders in January 2025. The Reverse Stock Split proportionally reduced the number of authorized shares of our common stock from 800,000,000 shares to 53,333,333 shares. The Reverse Stock Split did not change the par value of our common stock. In addition, proportionate adjustments were made to the number of shares of common stock available for issuance under our equity incentive plans; the number of shares underlying, and the exercise prices of, outstanding equity awards under such plans and outstanding warrants; and the conversion rates of outstanding convertible notes.

Open Market Sale Agreement

In February 2023, we entered into an Open Market Sale Agreement (the “Open Market Sale Agreement”) with Jefferies LLC, as agent (“Jefferies”). Under the Open Market Sale Agreement, we may issue and sell shares of our common stock having an aggregate offering price of up to $100.0 million (the “Shares”) from time to time through Jefferies (the “Open Market Offering”).

Under the Open Market Sale Agreement, Jefferies may sell the Shares by methods deemed to be an “at the market offering” as defined in Rule 415(a)(4) promulgated under the Securities Act of 1933, as amended (the “Securities Act”). We may sell the Shares in

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amounts and at times to be determined by us from time to time subject to the terms and conditions of the Open Market Sale Agreement, but we have no obligation to sell any of the Shares in the Open Market Offering.

We or Jefferies may suspend or terminate the offering of Shares upon notice to the other party and subject to other conditions. We have agreed to pay Jefferies commissions for its services in acting as agent in the sale of the Shares in the amount of up to 3.00% of gross proceeds from the sale of the Shares pursuant to the Open Market Sale Agreement. We have also agreed to provide Jefferies with customary indemnification and contribution rights.

We did not sell any Shares under the Open Market Sale Agreement during the years ended December 31, 2025, 2024 and 2023 As of December 31, 2025, $100.0 million of Shares were available for issuance and sale under the Open Market Sale Agreement.

Common Share Issuances

In October 2025, we issued (i) 1,487,917 shares of common stock at a price of $5.88 per share and (ii) accompanying warrants (the “2025 Placement Warrants”) to purchase 1,317,771 shares of common stock to certain institutional investors in a private placement for aggregate gross proceeds of approximately $8.8 million. Refer to Note 11, “Common Share Warrants” for additional detail on the 2025 Placement Warrants.

In October 2025, we issued a total of 5,736,065 shares of common stock of which: (i) 2,435,146 shares were issued to holders of the 2025 Notes to partially settle the 2025 Notes, (ii) 2,024,344 shares were issued to holders of the 2029 Notes to partially settle the 2029 Notes, (iii) 949,908 shares were issued to certain holders of our long-term obligations to pay various fees incurred in connection with the debt modifications that occurred in October 2025, and (iv) 326,667 shares were issued to our financial advisor. Refer to Note 10, “Long-Term Obligations” for additional detail on these transactions.

In October 2025, we issued a total of 2,298,723 shares of common stock pursuant to the cashless exercise of Pre-Funded Warrants (as defined below) to purchase an aggregate of 2,298,756 shares of common stock.

9. Stock-based Compensation

On May 19, 2022, our stockholders approved the 2022 Equity Incentive Plan (the “2022 Plan”), succeeding our 2013 Stock Incentive Plan (the “2013 Plan”), which has expired and under which no further grants may be made. The 2022 Plan provides for the grant of incentive stock options, non-statutory stock options, stock appreciation rights, restricted stock awards, RSU awards and other stock-based awards. On May 24, 2023, May 29, 2024, and May 28, 2025 our stockholders approved an amendment to the 2022 Plan to increase the number of shares of our common stock available for issuance under the 2022 Plan by 333,333 shares, 400,000 shares, and 450,000 shares, respectively. As of December 31, 2025, there were 283,228 shares available for future grants under the 2022 Plan.

Under the terms of the 2022 Plan, we granted stock options, RSUs, and PSUs to our employees, officers, directors, consultants and advisors. Stock options have a ten-year term and an exercise price equal to the fair market value of a share of our common stock on the grant date. Stock options and RSUs vest over a period of one to four years. PSUs will vest if certain performance goals are achieved over a certain performance period. Certain portions of certain PSU awards vest based on continuous service to the Company throughout the performance period even if the performance goal is not achieved.

During 2025, 2024, and 2023, we also granted stock options and RSUs through inducement grants outside of our stockholder approved equity compensation plans as permitted under the Nasdaq Stock Market listing rules to certain employees to induce them to accept employment with us (collectively, “Inducement Awards” which are made under the “2022 Inducement Plan”). In 2023 and 2024, the Board increased the number of shares reserved for issuance under the 2022 Inducement Plan by 80,000 shares and 66,667 shares, respectively. We assessed the terms of these Inducement Awards and determined there was no possibility that we would have to settle these awards in cash and therefore, equity accounting was applied. As of December 31, 2025, there were 39,626 shares available for future grants under the 2022 Inducement Plan.

As of December 31, 2025, we had 2,123,671 shares reserved for issuance, which includes shares available for future grants and outstanding stock options, RSUs and PSUs under the 2013 Plan, the 2022 Plan, and Inducement Awards (including the Inducement Awards granted under the 2022 Inducement Plan).

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Stock-based Compensation Expense

Total stock-based compensation expense recognized was as follows (in thousands):

For the Years Ended December 31,

The total stock-based compensation expense recognized by award type was as follows (in thousands):

For the Years Ended December 31,

Stock Options

The following table summarizes stock option activity related to the 2013 Plan, 2022 Plan, and Inducement Awards (including the stock option Inducement Awards granted under the 2022 Inducement Plan):

There were no stock options exercised during the years ended December 31, 2025 and 2024. The total intrinsic value of stock options exercised for the year ended December 31, 2023 was less than $0.1 million.

The fair value of each stock option granted is estimated on the date of grant using the Black-Scholes option-pricing model. The following table summarizes the assumptions used in calculating the fair value of the stock option awards:

For the Years Ended December 31,

Dividend —% —% —%

We use the simplified method to calculate the expected term as our historical exercise data does not provide a reasonable basis upon which to estimate the expected term. The expected term is applied to the stock option grant group as a whole, as we do not expect substantially different exercise or post-vesting termination behavior among our employee population. Our expected stock price volatility assumption is based on the historical volatility of our publicly traded stock. The risk-free interest rate is based on a treasury instrument whose term is consistent with the expected term of the stock options. We account for forfeitures as they occur.

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Using the Black-Scholes option-pricing model, the weighted-average grant date fair values of options granted during the years ended December 31, 2025, 2024 and 2023 was $5.86, $9.53 and $23.03 per share, respectively.

As of December 31, 2025, there was $1.5 million of unrecognized compensation expense related to unvested stock option awards, which is expected to be recognized over a weighted-average period of 2.7 years.

Restricted Stock Units and Performance-Based Restricted Stock Units

The following is a summary of RSU and PSU activity for the 2013 Plan, 2022 Plan, and Inducement Awards (including RSU Inducement Awards granted under the 2022 Inducement Plan):

Number ofSharesUnderlyingRSUs and PSUs Weighted-AverageGrant DateFair Value

The total fair value of RSUs and PSUs that vested during the years ended December 31, 2025, 2024 and 2023 was $1.6million, $2.8 million, and $2.9 million, respectively. As of December 31, 2025, there was $8.7 million of unrecognized compensation expense related to unvested RSUs and PSUs, which is expected to be recognized over a weighted-average period of 1.3 years.

Employee Stock Purchase Plan

We have an ESPP that permits eligible employees to enroll in six-month offering periods. Participants may purchase shares of our common stock, through payroll deductions, at a price equal to 85% of the fair market value of the common stock on the first or last day of the applicable offering period, whichever is lower. Purchase dates under the ESPP occur on or about May 1 and November 1 each year. On May 24, 2023, our stockholders approved an amendment and restatement of our ESPP (the “Amended & Restated ESPP”), which increased the number of shares of common stock authorized for issuance under the ESPP by 100,000 shares. On May 29, 2024, our stockholders approved an amendment to the Amended & Restated ESPP to increase the number of shares of our common stock available for issuance under the Amended & Restated ESPP by 333,333 shares. As of December 31, 2025, 165,461 shares of our common stock remained available for issuance under the Amended & Restated ESPP.

During the years ended December 31, 2025, 2024 and 2023, $0.8 million, $1.5 million and $1.1 million, respectively, was withheld from employees, on an after-tax basis, in order to purchase 145,936, 131,698 and 42,391shares of our common stock, respectively. As of December 31, 2025, there was $0.1 million of total unrecognized stock-based compensation expense related to the Amended & Restated ESPP. The expense is expected to be recognized over a period of four months.

The fair value of the option component of the shares purchased under the Amended & Restated ESPP was estimated using the Black-Scholes option-pricing model with the following weighted-average assumptions:

For the Years Ended December 31,

Expected term (in years) 0.5 0.4 - 0.5 0.5

Dividend —% —% —%

10. Long-Term Obligations

2025 Notes

In October 2018, we issued $172.5 million aggregate principal amount of the 2025 Notes in a private offering to qualified institutional buyers in reliance on Rule 144A under the Securities Act. The 2025 Notes were senior unsecured obligations, bore interest at a rate of 3.00% per year, and matured on October 15, 2025. Holders were able to convert the 2025 Notes at an initial

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conversion rate of 4.2049 shares of common stock per $1,000 principal amount (equivalent to an initial conversion price of approximately $237.82 per share of common stock) following July 15, 2025. No holders elected to convert their 2025 Notes. In connection with the issuance of the 2025 Notes, we incurred $5.6 million of debt issuance costs, which were amortized to interest expense using an effective interest rate of 3.53% over seven years.