Zymeworks Inc.

Previous wording

Our first internally developed product candidate, zanidatamab, is a novel bispecific antibody that targets two distinct domains of the human epidermal growth factor receptor 2 (“HER2”). Through rigorous scientific investigation, innovative protein engineering, and our proprietary Azymetric bispecific platform technology, we developed the unique binding mechanism of zanidatamab which enables it to bind to two extracellular sites on HER2. Zanidatamab’s unique binding properties result in multiple mechanisms of action that may enable it to address unmet need in patient populations with HER2-expressing cancers. We have entered into separate agreements with BeOne Medicines Ltd. (previously known as BeiGene, Ltd.) (“BeOne”) and Jazz Pharmaceuticals Ireland Limited (a subsidiary of Jazz Pharmaceuticals plc, collectively referred to as “Jazz”), granting to each of BeOne and Jazz exclusive rights to develop and commercialize zanidatamab in different territories. Zanidatamab is currently being evaluated in multiple global clinical trials as a potential best-in-class treatment for patients with HER2-expressing cancers.

Current wording

Our first internally developed product candidate, zanidatamab, is a novel bispecific antibody that targets two distinct domains of the human epidermal growth factor receptor 2 (“HER2”). Through rigorous scientific investigation, innovative protein engineering, and our proprietary Azymetric bispecific platform technology, we developed the unique binding mechanism of zanidatamab which enables it to bind to two extracellular sites on HER2. Zanidatamab’s unique binding properties result in multiple mechanisms of action that may enable it to address unmet need in patient populations with HER2-expressing cancers. We have entered into separate agreements with BeOne Medicines Ltd. (previously known as BeiGene, Ltd.) (together with its affiliates, “BeOne”) and Jazz Pharmaceuticals Ireland Limited (a subsidiary of Jazz Pharmaceuticals plc, collectively referred to as “Jazz”), granting to each of BeOne and Jazz exclusive rights to develop and commercialize zanidatamab in different territories. Zanidatamab is currently being evaluated in multiple global clinical trials as a potential best-in-class treatment for patients with HER2-expressing cancers.

Previous wording

Since our initial public offering (“IPO”) in 2017, we have funded our operations primarily through follow-on public offerings, including the issuance of pre-funded warrants, and payments received under our license and collaboration agreements. Payments received or receivables from our license and collaboration agreements include upfront fees, milestone and royalty payments, as well as research support and reimbursement payments. Prior to our IPO, we also received financing from private equity placements and the issuance of convertible debt, which was subsequently converted into equity securities, and a credit facility. From inception to June 30, 2025, we received $1,005.7 million, net of equity issuance costs, from these sources of financing including proceeds from exercises of stock options and employee stock purchase plans. As of June 30, 2025, we had $333.4 million of cash resources consisting of cash, cash equivalents and marketable securities.

Current wording

Since our initial public offering (“IPO”) in 2017, we have funded our operations primarily through follow-on public offerings, including the issuance of pre-funded warrants, and payments received under our license and collaboration agreements. Payments received or receivables from our license and collaboration agreements include upfront fees, milestone and royalty payments, as well as research support and reimbursement payments. Prior to our IPO, we also received financing from private equity placements and the issuance of convertible debt, which was subsequently converted into equity securities, and a credit facility. From inception to September 30, 2025, we received $1,019.4 million, net of equity issuance costs, from these sources of financing including proceeds from exercises of stock options and employee stock purchase plans. As of September 30, 2025, we had $299.4 million of cash resources consisting of cash, cash equivalents and marketable securities.

Previous wording

We reported a net loss of $20.3 million for the six months ended June 30, 2025 and through June 30, 2025, we had an accumulated deficit of $850.7 million. Over the next several years, we expect to continue to incur losses as we increase our research and development expenditures in connection with the ongoing development of our product candidates and other clinical, preclinical and regulatory activities.

Current wording

We reported a net loss of $39.9 million for the nine months ended September 30, 2025 and through September 30, 2025, we had an accumulated deficit of $886.5 million. Over the next several years, we expect to continue to incur losses as we increase our research and development expenditures in connection with the ongoing development of our product candidates and other clinical, preclinical and regulatory activities.

Previous wording

ZW191: A clinical-stage ADC that targets folate receptor α (“FRα”)-expressing tumors including ovarian cancer, endometrial cancer, and non-small cell lung cancer (“NSCLC”), is built using our novel, bystander active, TOPO1i payload technology, ZD06519. The FRα-targeting monoclonal antibody incorporated in ZW191 was selected based on compelling internalization characteristics to enable targeting of high, mid, and low levels of FRα expression. A drug-antibody-ratio (“DAR”) of eight was selected due to the restricted expression profile of FRα in normal tissues and to enhance our ability to deliver payload to tumors with lower levels of FRα. FRα is a clinically validated target, found in approximately 75% of high-grade serous ovarian carcinomas, 50% of endometrial cancers, and in 70% of NSCLC. Preclinical data demonstrate strong ZW191 activity across a range of FRα-expressing patient-derived xenografts, including models with low levels of FRα. The ability to target lower levels of FRα is in part due to the DAR-eight format and the observed superior internalization, payload delivery, and tissue penetration derived from the ZW191 monoclonal antibody compared to other FRα monoclonal antibodies used in ADCs currently or previously in development. In a good laboratory practices (“GLP”) toxicology study, ZW191 achieved a highest non-severely toxic dose (“HNSTD”) in non-human primates of 60 mg/kg, which presents a compelling profile and enables the expectation of potentially achieving an efficacious dose level in the Phase 1 clinical trial. We are optimistic about the prospects of ZW191 and we believe the design features and preclinical profile support the potential of ZW191 to target cancers with lower levels of FRα. This would allow ZW191 to potentially unlock efficacy for both ovarian cancer patients who are unable to receive Elahere, as it is only approved in FRα-high platinum-resistant ovarian cancer (“PROC”), and other indications including endometrial and NSCLC which typically express lower levels of FRα. We are currently recruiting patients in an ongoing global Phase 1, open-label, multicenter study of ZW191, registered under NCT06555744 on clinicaltrials.gov. The starting dose level (Dose Level 1) is 1.6 mg/kg, administered once every three weeks (Q3W) by intravenous infusion. Approximately six dose levels are planned, with escalation guided by safety and tolerability using a modified toxicity probability interval design. The study aims to enroll 145 participants with advanced solid tumors, including ovarian, endometrial, and non-small cell lung cancers, across North America, Europe, and the Asia-Pacific region. The study is designed to evaluate the safety, tolerability, pharmacokinetics, and preliminary anti-tumor activity of ascending doses of ZW191.

Current wording

ZW191: A clinical-stage ADC that targets folate receptor α (“FRα”)-expressing tumors including ovarian cancer, endometrial cancer, and non-small cell lung cancer (“NSCLC”), is built using our novel, bystander active, TOPO1i payload technology, ZD06519. The FRα-targeting monoclonal antibody incorporated in ZW191 was selected based on compelling internalization characteristics to enable targeting of high, mid, and low levels of FRα expression. A drug-antibody-ratio (“DAR”) of eight was selected due to the restricted expression profile of FRα in normal tissues and to enhance our ability to deliver payload to tumors with lower levels of FRα. FRα is a clinically validated target, found in approximately 75% of high-grade serous ovarian carcinomas, 50% of endometrial cancers, and in 70% of NSCLC. Preclinical data demonstrate strong ZW191 activity across a range of FRα-expressing patient-derived xenografts, including models with low levels of FRα. The ability to target lower levels of FRα is in part due to the DAR-eight format and the observed superior internalization, payload delivery, and tissue penetration derived from the ZW191 monoclonal antibody compared to other FRα monoclonal antibodies used in ADCs currently or previously in development. In a good laboratory practices (“GLP”) toxicology study, ZW191 achieved a highest non-severely toxic dose (“HNSTD”) in non-human primates of 60 mg/kg, which presents a compelling profile and enables the expectation of potentially achieving an efficacious dose level in the Phase 1 clinical trial. We are currently recruiting patients in an ongoing global Phase 1, open-label, multicenter study of ZW191, registered under NCT06555744 on clinicaltrials.gov. The study aims to enroll approximately 145 participants with advanced solid tumors, including ovarian, endometrial, and non-small cell lung cancers, across North America, Europe, and the Asia-Pacific region. The study is designed to evaluate the safety, tolerability, pharmacokinetics, and preliminary anti-tumor activity of ascending doses of ZW191. In October 2025, we presented initial clinical data from the Phase 1 trial. Based on the preliminary efficacy data and the tolerable safety profile observed, we intend to initiate dose optimization in ovarian cancer in 4Q-2025 to further evaluate ZW191’s clinical activity and safety to help inform our registrational strategy.

Previous wording

ZW251: A potential first-in-class clinical-stage ADC molecule designed for the treatment of glypican 3 (“GPC3”)-expressing hepatocellular carcinoma (“HCC”), incorporates the same Zymeworks proprietary bystander-active TOPO1i payload utilized in ZW191 (anti-FRα) and ZW220 (anti-sodium-dependent phosphate transporter 2b (“NaPi2b”)), ZD06519. The GPC3-targeting monospecific antibody incorporated in ZW251 was selected based on favorable binding and internalization properties to enable targeting of a range of GPC3-expressing tumors. A DAR of four was selected for this program as a lower DAR potentially could unlock a broader range of dose levels, a potential benefit as HCC patients are commonly challenged by impairment of liver function as a result of chronic liver disease and cirrhosis. GPC3, a glycosylphosphatidylinositol (“GPI”)-anchored cell surface oncofetal antigen, is over-expressed in most HCC patients (>75%), and displays minimal normal adult tissue expression, making it an appealing ADC target. In preclinical studies, anti-tumor activity for ZW251 was observed in multiple patient-derived xenograft models of HCC reflecting a range of GPC3 over-expression. In non-GLP non-human primate studies, ZW251 was tolerated at doses up to 120 mg/kg, suggesting the potential for high doses in humans. We are encouraged by published research demonstrating the potential of targeting GPC3 with an antibody in HCC patients as evidenced by tumor localization of iodine radio-labeled condrituzumab, a clinical-stage anti-GPC3 monoclonal antibody, and believe that ADC-based targeting of GPC3 could enable a novel and effective approach to treatment of HCC. In July 2025, we announced that the investigational new drug (“IND”) application for ZW251, a first-in-class GPC3-targeting antibody drug conjugate, was cleared by the FDA. We plan to commence Phase 1 clinical studies for ZW251 in 2025.

Current wording

ZW251: A potential first-in-class clinical-stage ADC molecule designed for the treatment of glypican 3 (“GPC3”)-expressing hepatocellular carcinoma (“HCC”), incorporates the same Zymeworks proprietary bystander-active TOPO1i payload utilized in ZW191 (anti-FRα) and ZW220 (anti-sodium-dependent phosphate transporter 2b (“NaPi2b”)), ZD06519. The GPC3-targeting monospecific antibody incorporated in ZW251 was selected based on favorable binding and internalization properties to enable targeting of a range of GPC3-expressing tumors. A DAR of four was selected for this program as a lower DAR potentially could unlock a broader range of dose levels, a potential benefit as HCC patients are commonly challenged by impairment of liver function as a result of chronic liver disease and cirrhosis. GPC3, a glycosylphosphatidylinositol (“GPI”)-anchored cell surface oncofetal antigen, is over-expressed in most HCC patients (>75%), and displays minimal normal adult tissue expression, making it an appealing ADC target. In preclinical studies, anti-tumor activity for ZW251 was observed in multiple patient-derived xenograft models of HCC reflecting a range of GPC3 over-expression. In non-GLP non-human primate studies, ZW251 was tolerated at doses up to 120 mg/kg, suggesting the potential for high doses in humans. We are encouraged by published research demonstrating the potential of targeting GPC3 with an antibody in HCC patients as evidenced by tumor localization of iodine radio-labeled condrituzumab, a clinical-stage anti-GPC3 monoclonal antibody, and believe that ADC-based targeting of GPC3 could enable a novel and effective approach to treatment of HCC. In July 2025, we announced that the investigational new drug (“IND”) application for ZW251, a first-in-class GPC3-targeting antibody drug conjugate, was cleared by the FDA. We are currently recruiting patients in an ongoing global Phase 1, open-label, multicenter study of ZW251, registered under NCT07164313 on clinicaltrials.gov. The study aims to enroll approximately 100 participants with advanced solid tumors, including hepatocellular carcinoma (“HCC”), across North America, Europe, and the Asia-Pacific region. The study is designed to evaluate the safety, tolerability, pharmacokinetics, and preliminary anti-tumor activity of ZW251.

Previous wording

ZW171: A clinical-stage multispecific antibody built using our Azymetric platform, is a novel 2 + 1 format TCE targeting mesothelin (“MSLN”)-expressing cancers. ZW171 has a unique geometry, with two single-chain fragment variable arms targeting MSLN and one Fab arm targeting the cluster of differentiation 3 protein (“CD3”) component of the T cell receptor, to redirect the body’s natural immune system to fight cancer cells. Preclinical data demonstrated in vivo anti-tumor activity, with engagement in high-expressing cells but not low-expressing cells, mitigating the risk of on-target, off-tumor toxicities. MSLN has strong expression in ovarian cancer (~84%), with moderate to strong expression in NSCLC (~36%), making it an appealing target for therapeutic development with our proprietary TCE technology. In preclinical studies, ZW171 has demonstrated potent preferential killing of tumor cells expressing relatively medium to high thresholds of MSLN while sparing cell line models representative of normal tissue MSLN expression, demonstrating reduced potential for on-target-off tumor toxicity. Incorporation of a low affinity anti-CD3 binding domain further mitigates the risk of peripheral T cell activation and cytokine release syndrome. Preclinical data demonstrated that ZW171 exhibits greater anti-tumor activity compared to benchmark in MSLN-expressing tumor models and is well tolerated in cynomolgus monkeys up to 30 mg/kg. We are actively recruiting patients in the global Phase 1, open-label, multicenter study of ZW171, registered under NCT06523803 on clinicaltrials.gov. The study employs a subcutaneous step-up dosing regimen on Days 1, 8, and 15 of each 21-day cycle. The starting dose level (Dose Level 1) is based on a quantitative systems pharmacology-guided minimal anticipated biological effect level (MABEL) approach and includes sequential doses of 4.2 µg (Cycle 1 Day 1), 12.6 µg (Cycle 1 Day 8), and 38.0 µg (Cycle 1 Day 15). Dose levels 2 and above are determined by the data from the prior dose based on pre-specified rules within the protocol. The modified toxicity probability interval (mTPI) design is being used to establish the maximum tolerated dose and recommended dose for expansion. The study aims to enroll 160 adult patients with advanced MSLN-expressing cancers in North America, Europe, and the Asia-Pacific region. The study is designed to evaluate the safety, tolerability, pharmacokinetics, and preliminary anti-tumor activity of ascending doses of ZW171.

Current wording

ZW171: A clinical-stage multispecific antibody built using our Azymetric platform, is a novel 2 + 1 format TCE targeting mesothelin (“MSLN”)-expressing cancers. ZW171 has a unique geometry, with two single-chain fragment variable arms targeting MSLN and one Fab arm targeting the cluster of differentiation 3 protein (“CD3”) component of the T cell receptor, to redirect the body’s natural immune system to fight cancer cells. Preclinical data demonstrated in vivo anti-tumor activity, with engagement in high-expressing cells but not low-expressing cells, mitigating the risk of on-target, off-tumor toxicities. MSLN has strong expression in ovarian cancer (~84%), with moderate to strong expression in NSCLC (~36%), making it an appealing target for therapeutic development with our proprietary TCE technology. In preclinical studies, ZW171 has demonstrated potent preferential killing of tumor cells expressing relatively medium to high thresholds of MSLN while sparing cell line models representative of normal tissue MSLN expression, demonstrating reduced potential for on-target-off tumor toxicity. Incorporation of a low affinity anti-CD3 binding domain further mitigates the risk of peripheral T cell activation and cytokine release syndrome. Preclinical data demonstrated that ZW171 exhibits greater anti-tumor activity compared to benchmark in MSLN-expressing tumor models and is well tolerated in cynomolgus monkeys up to 30 mg/kg. In September 2025, we announced the decision to voluntarily discontinue clinical development of ZW171.

Previous wording

In May 2025, we presented new preclinical data for ZW1528, a novel IL-4Rα x IL-33 bispecific molecule designed to address respiratory inflammation, at the American Thoracic Society International Conference. Key findings for ZW1528 include:

Current wording

In September 2025, we presented new preclinical data for ZW1528 at the European Respiratory Society Congress.

Previous wording

Our royalty revenue from Jazz and BeiGene was $0.6 million in the three months ended June 30, 2025, driven principally by $5.5 million of net product sales of Ziihera® by Jazz in the three months ended June 30, 2025.

Current wording

Our royalty revenue from Jazz and BeOne was $1.0 million in the three months ended September 30, 2025, driven primarily by net product sales of Ziihera® by Jazz in the three months ended September 30, 2025.

Previous wording

In addition to the payments we have received through our collaboration agreements with Jazz and BeOne relating to zanidatamab and zanidatamab zovodotin, as of June 30, 2025, we have received approximately $208.1 million in the form of non-refundable upfront and milestone payments from platform partnership and collaboration agreements. We continue to have revenue-generating strategic partnerships and collaborations with respect to our Azymetric, EFECT and drug conjugate therapeutic platforms with the following pharmaceutical companies: Celgene Corporation (now a Bristol-Myers Squibb company, “BMS”), GlaxoSmithKline Intellectual Property Development Limited (“GSK”), Daiichi Sankyo Co., Ltd. (“Daiichi Sankyo”), J&J (previously known as Janssen Biotech, Inc.), and Merck Sharp & Dohme Research GmbH (“Merck”). Through these strategic partnerships and collaborations, as of June 30, 2025, we remain eligible to receive up to $1.01 billion in preclinical and development milestone payments and up to $3.08 billion in commercial milestone payments, as well as tiered royalties on potential future product sales, pending regulatory approval. It is possible, however, that our strategic partners’ programs will not advance as currently contemplated, which would negatively affect the amount of development and commercial milestone payments and royalties on potential future product sales we may receive. Importantly, these partnerships include predominantly non-target-exclusive licenses for any of our therapeutic platforms, so we maintain the ability to develop therapeutics directed to many high-value targets using our platforms. There have not been any material changes to the key terms of any of our licensing and collaboration agreements since December 31, 2024. For further information on the terms and conditions of our existing collaboration and license agreements, please refer to “Item 1. Business - Strategic Partnerships and Collaborations” of our Annual Report on Form 10-K for the year ended December 31, 2024.

Current wording

In addition to the payments we have received through our collaboration agreements with Jazz and BeOne relating to zanidatamab and zanidatamab zovodotin, as of September 30, 2025, we have received $208.4 million in the form of non-refundable upfront and milestone payments from platform partnership and collaboration agreements. We continue to have revenue-generating strategic partnerships and collaborations with respect to our Azymetric, EFECT and drug conjugate therapeutic platforms with the following pharmaceutical companies: Celgene Corporation (now a Bristol-Myers Squibb company, “BMS”), GlaxoSmithKline Intellectual Property Development Limited (“GSK”), Daiichi Sankyo Co., Ltd. (“Daiichi Sankyo”), J&J, and Merck Sharp & Dohme Research GmbH (“Merck”). Through these strategic partnerships and collaborations, as of September 30, 2025, we remain eligible to receive up to $1.01 billion in preclinical and development milestone payments and up to $3.08 billion in commercial milestone payments, as wellas tiered royalties on potential future product sales, pending regulatory approval. It is possible, however, that our strategic partners’ programs will not advance as currently contemplated, which would negatively affect the amount of development and commercial milestone payments and royalties on potential future product sales we may receive. Importantly, these partnerships include predominantly non-target-exclusive licenses for any of our therapeutic platforms, so we maintain the ability to develop therapeutics directed to many high-value targets using our platforms. There have not been any material changes to the key terms of any of our licensing and collaboration agreements since December 31, 2024. For further information on the terms and conditions of our existing collaboration and license agreements, please refer to “Item 1. Business - Strategic Partnerships and Collaborations” of our Annual Report on Form 10-K for the year ended December 31, 2024.

Previous wording

There have been no material changes in our critical accounting policies and significant judgments and estimates during the three and six months ended June 30, 2025 as compared to what has been described in our most recent annual consolidated financial statements.

Current wording

There have been no material changes in our critical accounting policies and significant judgments and estimates during the three and nine months ended September 30, 2025 as compared to what has been described in our most recent annual consolidated financial statements.

Previous wording

Results of Operations for the Three and Six Months Ended June 30, 2025 and 2024

Current wording

Results of Operations for the Three and Nine Months Ended September 30, 2025 and 2024

Previous wording

Total revenue increased by $29.5 million in the three months ended June 30, 2025 compared to the same period in 2024. Revenue for the three months ended June 30, 2025 included a $7.5 million fee upon BMS’s exercise of its commercial license option in relation to our 2014 licensing and collaboration agreement with BMS, $20.0 million of non-refundable milestone revenue from BeOne upon conditional approval of the BLA for zanidatamab for second-line treatment of HER2+ BTC by the NMPA in China, as well as the recognition of $18.3 million of deferred revenue in relation to the achievement of that milestone. Additionally, revenue included $2.3 million for development support and drug supply revenue and $0.6 million royalty revenue from Jazz and BeOne. Revenue for the same period in 2024 included $10.8 million for development support and drug supply revenue from Jazz, $8.0 million of milestone revenue from BeOne in relation to the acceptance by the CDE of the NMPA in China of the BLA for zanidatamab for second-line treatment of HER2+ BTC and $0.4 million from BeOne for drug supply.

Current wording

Total revenue increased by $11.6 million in the three months ended September 30, 2025 compared to the same period in 2024. Revenue for the three months ended September 30, 2025 included$25.0 million of non-refundable milestone revenue from J&J due to the achievement of research milestones in the Phase 3 clinical trial of pasritamig,$1.4 million for development support and drug supply revenue from Jazz and $1.0 million of royalty revenue from Jazz and BeOne. Additionally, revenue includeda $0.3 million fee upon extension of the research term under our 2020 licensing agreement with Merck. Revenue for the same period in 2024 included $12.1 million for development support and drug supply revenue from Jazz and $2.5 million of milestone revenue from GSK in relation to the sequence pair nomination under the 2016 licensing agreement, and $1.4 million of drug supply revenue from BeOne.

Previous wording

Total revenue increased by $46.5 million in the six months ended June 30, 2025 compared to the same period in 2024. Revenue for the six months ended June 30, 2025 included $14.0 million of milestone revenue from GSK in relation to a clinical milestone under our 2016 platform technology transfer and license agreement, $3.1 million of milestone revenue from Daiichi Sankyo following the first patient dosed in a clinical trial related to the 2018 license agreement, a $7.5 million fee upon BMS’s exercise of its commercial license option in relation to our 2014 licensing and collaboration agreement with BMS, $20.0 million of non-refundable milestone revenue from BeOne upon conditional approval of the BLA for zanidatamab for second-line treatment of HER2+ BTC by the NMPA in China, as well as the recognition of $18.3 million of deferred revenue in relation to the achievement of that milestone. Additionally, revenue included $11.9 million for development support and drug supply revenue and $0.8 million of royalty revenue from Jazz, and $0.2 million of drug supply revenue from BeOne. Revenue for the same period in 2024 included $20.7 million for development support and drug supply revenue from Jazz, $8.0 million of milestone revenue from BeOne inrelation to the acceptance by the CDE of the NMPA in China of the BLA for zanidatamab for second-line treatment of HER2+ BTC, $0.4 million from BeOne for drug supply and $0.2 million from our partners for research support and other payments.

Current wording

$7.5 million fee upon BMS’s exercise of its commercial license option in relation to our 2014 licensing and collaboration agreement with BMS, $20.0 million of non-refundable milestone revenue from BeOne upon conditional approval of the BLA for zanidatamab for second-line treatment of HER2+ BTC by the NMPA in China, as well as the recognition of $18.3 million of deferred revenue in relation to the achievement of that milestone. Additionally, revenue included $13.3 million for development support and drug supply revenue and $1.6 million of royalty revenue from Jazz, and $0.2 million of drug supply revenue and $0.2 million of royalty revenue from BeOne and a $0.3 million fee upon extension of the research term under our 2020 licensing agreement with Merck. Revenue for the same period in 2024 included $32.8 million for development support and drug supply revenue from Jazz, $8.0 million of milestone revenue from BeOne in relation to the acceptance by the CDE of the NMPA in China of the BLA for zanidatamab for second-line treatment of HER2+ BTC, $2.5 million of milestone revenue from GSK in relation to the sequence pair nomination under the 2016 licensing agreement, $1.8 million from BeOne for drug supply revenue and $0.2 million from our partners for research support and other payments.

Previous wording

Research and development expense increased by $5.2 million for the three months ended June 30, 2025 compared to the same period in 2024. The increase in research and development expense in 2025 was primarily due to an increase in expenses for ZW171 and ZW191 due to progression of clinical studies and the activation of initial clinical trial sites and an increase in other preclinical and research program expenses primarily due to expenses for IND enabling studies for ZW209. These were partially offset by a decrease in expenses for ZW220 as IND enabling toxicology studies were largely completed in early 2025, prior to the decision to pause the program, and a decrease in expenses for zanidatamab zovodotin as this program was discontinued. The increase in other unallocated expenses were primarily due to reversal of a contingent liability provision in 2024 following the decision to discontinue the zanidatamab zovodotin program.

Current wording

Research and development expense decreased by $0.8 million for the three months ended September 30, 2025 compared to the same period in 2024. The decrease was primarily due to a reduction in in expenses for ZW220, as IND enabling toxicology studies were largely completed in early 2025 before the pause on this program, and a decrease in expenses for ZW251, due to the completion of manufacturing activities for clinical drug supply in 2024 which were partly offset by an increase in clinical start-up activities. Expenses for zanidatamab decreased as a result of reduced clinical support provided to Jazz following BLA approval in 2024 and expenses for zanidatamab zovodotin decreased as this program was discontinued. The decrease was partially offset by an increase in other preclinical and research program expenses, primarily due to expenses for GMP manufacturing and toxicology studies for ZW209 and IND enabling studies for ZW1528, and higher costs for ZW171 and ZW191, due to the progression of clinical studies.

Previous wording

Research and development expense increased by $9.0 million for the six months ended June 30, 2025 compared to the same period in 2024. The increase in research and development expense in 2025 was primarily due to an increase in clinical trial expenses for ZW171; increased expenses for ZW251 due to expenses for IND enabling studies and GMP activities as well as clinical start-up costs; and an increase in other preclinical and research program expenses, primarily due to expenses for IND enabling studies for ZW209. These were partially offset by a decrease in expenses for ZW220 due to the decision to pause the program; a decrease in expenses for zanidatamab as a result of reduced clinical support provided to Jazz following BLA approval in 2024, and a decrease in expenses for zanidatamab zovodotin as this program was discontinued. The increase in salaries and benefits in 2025 was primarily due to changes in headcount, while stock-based compensation expense in 2025 increased primarily due to new stock award grants during the six months ended June 30, 2025. Other unallocated expenses increased primarily due to reversal of a contingent liability provision in 2024 following the decision to discontinue zanidatamab zovodotin program and an increase in consulting and rent expenses.

Current wording

Research and development expense increased by $8.2 million for the nine months ended September 30, 2025 compared to the same period in 2024. The increase in research and development expense was primarily due to other preclinical and research program expenses, due to expenses for GMP manufacturing toxicology studies and other IND enabling studies for ZW209 and ZW1528. Costs increased in ZW171, ZW191 and ZW251 due to the progression of the clinical studies, clinical drug supply expenses and start-up costs. These were partially offset by a decrease in expenses for ZW220 as a majority of the preclinical development studies were completed and due to the decision to pause this program; a decrease in expenses for zanidatamab as a result of reduced clinical support provided to Jazz following BLA approval in 2024, and a decrease in expenses for zanidatamab zovodotin as this program was discontinued. The increase in stock-based compensation expense in 2025 was primarily due to new stock award grants in 2025. Other unallocated expenses increased primarily due to reversal of a contingent liability provision in 2024 following the decision to discontinue zanidatamab zovodotin program and an increase in consulting and facilities expenses.

Previous wording

General and administrative expense increased by $0.4 million for the six months ended June 30, 2025 compared to the same period in 2024. The increase in general and administrative expense was primarily due to increase in stock-based compensation expense as a result of new stock award grants in 2025 and an increase in depreciation and amortization expenses. This was partially offset by a decrease in consulting expenses.

Current wording

General and administrative expense increased by $0.2 million for the three months ended September 30, 2025 compared to the same period in 2024. The increase in general and administrative expense was primarily due to an increase in stock-based compensation expense as a result of new stock award grants in 2025 and an increase in consulting fees. This was partially offset by a decrease in salaries and benefits due to reduced headcount as well as a decrease in information technology expenses.

Previous wording

General and administrative expense decreased by $0.7 million for the three months ended June 30, 2025 compared to the same period in 2024. The decrease in general and administrative expense was primarily due to a decrease in consulting and rent expenses. This was partially offset by an increase in stock-based compensation expense as a result of new stock award grants in 2025 and an increase in depreciation and amortization expenses.

Current wording

General and administrative expense increased by $0.8 million for the nine months ended September 30, 2025 compared to the same period in 2024. The increase in general and administrative expense was primarily due to an increase in stock-based compensation expense as a result of new stock award grants in 2025, an increase in amortization expenses for information technology systems and an increase in professional fees. This was partially offset by a decrease in salaries and benefits due to reduced headcount, a decrease in rent expense due to the termination of our long-term facility lease in Seattle in 2024, as well as a decrease in expenses for software subscriptions.

Previous wording

During the three months ended June 30, 2024, we recorded an impairment charge of $17.3 million as a result of our decision to discontinue the zanidatamab zovodotin clinical development program which utilized the technology represented by acquired IPR&D assets.

Current wording

During the nine months ended September 30, 2024, we recorded an impairment charge of $17.3 million as a result of our decision to discontinue the zanidatamab zovodotin clinical development program which utilized the technology represented by acquired IPR&D assets.

Previous wording

Other income, net decreased by $2.5 million for the three months ended June 30, 2025 compared to the same period in 2024. Other income, net for 2025 included $3.4 million in interest income, partially offset by $0.6 million in net foreign exchange loss and other miscellaneous amounts. Other income, net for the three months ended June 30, 2024 included $5.2 million in interest income and a $0.1 million net foreign exchange gain and other miscellaneous amounts. The decrease in interest income was due to a reduction in the balances of our cash, cash equivalents and marketable securities, due to operating cash requirements, and due to a decrease in the average yield of these investments compared to the same period in 2024.

Current wording

Other income, net decreased by $0.8 million for the three months ended September 30, 2025 compared to the same period in 2024. Other income, net for 2025 included $3.5 million in interest income and $0.3 million in net foreign exchange gain and other miscellaneous amounts. Other income, net for the three months ended September 30, 2024 included $4.8 million in interest income partially offset by $0.2 million net foreign exchange loss and other miscellaneous amounts. The decrease in interest income was due to a reduction in the balances of our cash, cash equivalents and marketable securities, due to operating cash requirements, and due to a decrease in the average yield of these investments compared to the same period in 2024.

Previous wording

Other income, net decreased by $5.2 million for the six months ended June 30, 2025 compared to the same period in 2024. Other income, net for 2025 included $6.9 million in interest income, partially offset by $0.6 million in net foreign exchange loss and other miscellaneous amounts. Other income, net for the six months ended June 30, 2024 included $11.1 million in interest income and $0.4 million in net foreign exchange gain and other miscellaneous amounts. The decrease in interest income was due to a reduction in the balances of our cash, cash equivalents and marketable securities, due to operating cash requirements, and due to a decrease in the average yield of these investments compared to the same period in 2024.

Current wording

Other income, net decreased by $6.0 million for the nine months ended September 30, 2025 compared to the same period in 2024. Other income, net for 2025 included $10.4 million in interest income, partially offset by $0.3 million in net foreign exchange loss and other miscellaneous amounts. Other income, net for the nine months ended September 30, 2024 included $15.9 million in interest income and $0.2 million in net foreign exchange gain and other miscellaneous amounts. The decrease in interest income was due to a reduction in the balances of our cash, cash equivalents and marketable securities, due to operating cash requirements, and due to a decrease in the average yield of these investments compared to the same period in 2024.

Previous wording

Income tax expense increased by $0.2 million for the six months ended June 30, 2025, compared to the same period in 2024. The increase was primarily due to withholding taxes incurred on revenue recognized in the period.

Current wording

Income tax expense increased by $1.2 million for the nine months ended September 30, 2025, compared to the same period in 2024. The increase was primarily due to an increase in U.S. taxes due to the Subpart F income rules and withholding taxes incurred on revenue recognized in the period.

Previous wording

As of June 30, 2025, we had $333.4 million of cash, cash equivalents, and marketable securities, comprised of $98.3 million in cash and cash equivalents and $235.1 million in marketable securities.

Current wording

As of September 30, 2025, we had $299.4 million of cash, cash equivalents, and marketable securities, comprised of $64.8 million in cash and cash equivalents and $234.5 million in marketable securities.

Previous wording

The following table represents a summary of our cash flows for the six months ended June 30, 2025 and 2024:

Current wording

The following table represents a summary of our cash flows for the nine months ended September 30, 2025 and 2024:

Previous wording

During the six months ended June 30, 2025, cash provided by operating activities was $8.7 million compared to $62.7 million of cash used in operating activities for the same period in 2024. The positive change in net cash from operating activities was primarily due to milestone revenues during 2025 and favorable movements in working capital compared to the same period in the prior year.

Current wording

During the nine months ended September 30, 2025, cash used in operating activities was $22.7 million compared to $68.5 million of cash used in operating activities for the same period in 2024. The positive change in net cash used in operating activities was primarily due to milestone revenues received during 2025.

Previous wording

Net cash provided by financing activities for the six months ended June 30, 2025 included net proceeds of $2.2 million from stock option exercises and $0.5 million from the issuance of shares of common stock under our employee stock purchase plan. Net cash provided by financing activities for the six months ended June 30, 2024 included net proceeds of $2.9 million from stock option exercises and $0.4 million from the issuance of shares of common stock in relation to our employee stock purchase plan.

Current wording

Net cash provided by financing activities for the nine months ended September 30, 2025 included net proceeds of $5.0 million from a private placement, $10.1 million from stock option exercises and $1.4 million from the issuance of shares of common stock under our employee stock purchase plan. These were partially offset by $16.2 million used for the Repurchase Program. Net cash used in financing activities for the nine months ended September 30, 2024 included $20.6 million used for the Repurchase Program partially offset by net proceeds of $8.1 million from stock option exercises and $0.9 million from the issuance of shares of common stock under our employee stock purchase plan.

Previous wording

Net cash provided by investing activities for the six months ended June 30, 2025 primarily related to net proceeds from marketable securities of $22.1 million partially offset by cash outflows of $1.2 million for expenditures for office equipment and software implementation. Net cash used in investing activities for the six month period ended June 30, 2024 primarily related to net purchases of marketable securities of $25.5 million and cash outflows of $1.8 million for expenditures for software implementation and acquisition of property and equipment in our office and laboratory spaces in Canada and the United States.

Current wording

Net cash provided by investing activities for the nine months ended September 30, 2025 primarily related to net proceeds from marketable securities of $22.9 million partially offset by cash outflows of $1.6 million for expenditures for office equipment and software implementation. Net cash provided by investing activities for the nine month period ended September 30, 2024 primarily related to net proceeds from marketable securities of $47.7 million partially offset by cash outflows of $2.8 million for expenditures for software implementation and acquisition of property and equipment in our office and laboratory spaces in Canada and the United States.

Previous wording

Additionally, on August 1, 2024, our board of directors authorized the Repurchase Program, under which we may repurchase up to $60.0 million of our common stock. As of the date of this report, there is $30.0 million of remaining capacity under the Repurchase Program. The shares may be repurchased from time to time in open market transactions, or other means in accordance with Rule 10b5-1 of the Exchange Act and Rule 10b-18 of the Exchange Act. As of June 30, 2025, we have repurchased 2,545,402 shares of our common stock under the Repurchase Program. The timing, number of shares repurchased, and prices paid for any additional shares of the stock repurchased under this program will depend on general business and market conditions as well as corporate and regulatory limitations, prevailing stock prices, and other considerations. The Repurchase Program may be suspended or discontinued at any time and does not obligate us to acquire any additional shares of common stock.

Current wording

Additionally, on August 1, 2024, our board of directors authorized the Repurchase Program, under which we may repurchase up to $60.0 million of our common stock. As of September 30, 2025, there was $14.3 million of remaining capacity under the Repurchase Program. The shares may be repurchased from time to time in open market transactions, or other means in accordance with Rule 10b5-1 of the Exchange Act and Rule 10b-18 of the Exchange Act. As of September 30, 2025, we have repurchased 3,573,735 shares of our common stock under the Repurchase Program. The timing, number of shares repurchased, and prices paid for any additional shares of the stock repurchased under this program will depend on general business and market conditions as well as corporate and regulatory limitations, prevailing stock prices, and other considerations. The Repurchase Program may be suspended or discontinued at any time and does not obligate us to acquire any additional shares of common stock.

Previous wording

Our authorized share capital consists of 1,000,000,000 shares of stock, consisting of 900,000,000 shares of common stock, par value $0.00001 per share, and 100,000,000 shares of preferred stock, par value 0.00001 per share. As of August 5, 2025, 75,166,196 shares of common stock were issued and outstanding. In addition, as of August 5, 2025, we had 4,738,673 shares of common stock issuable pursuant to 4,738,673 exercisable outstanding stock options, 4,504,648 shares of common stock issuable pursuant to 4,504,648 outstanding options that were not exercisable at that date, and 1,842,218 shares of common stock issuable upon vesting of outstanding restricted stock units.

Current wording

74,836,534 shares of common stock were issued and outstanding. In addition, as of November 4, 2025, we had 4,314,446 shares of common stock issuable pursuant to 4,314,446 exercisable outstanding stock options, 4,425,961 shares of common stock issuable pursuant to 4,425,961 outstanding options that were not exercisable at that date, and 1,947,941 shares of common stock issuable upon vesting of outstanding restricted stock units.

Previous wording

As of August 5, 2025, 855,344 Exchangeable Shares have been exchanged on a one-to-one basis for 855,344 shares of our common stock and 569,189 Exchangeable Shares are held by former Zymeworks BC shareholders and are exchangeable on a one-to-one basis, subject to adjustment, for up to 569,189 shares of our common stock.

Current wording

As of November 4, 2025, 871,349 Exchangeable Shares have been exchanged on a one-to-one basis for 871,349 shares of our common stock and 553,184 Exchangeable Shares are held by former Zymeworks BC shareholders and are exchangeable on a one-to-one basis, subject to adjustment, for up to 553,184 shares of our common stock.