B7-H4

Company unveils new innovative Oncology organization, strategic vision and approach, following the Seagen acquisition in late 2023 Robust portfolio and R&D engine with 8+ potential blockbuster medicines by 2030 Multiple near- and mid-term catalysts expected to help drive long-term sustainable growth NEW YORK--(BUSINESS WIRE)-- At a meeting with the investment community today, Pfizer Inc. (NYSE: PFE) outlined its strategic priorities for the newly formed Oncology organization — and how its deep and diverse pipeline, industry-leading Oncology expertise, and anticipated near- and mid-term catalysts are expected to position the company to deliver strong growth and shareholder value. A replay of the webcast and related materials, including the presentations and a summary and transcript, will be made available on the Pfizer investor relations website at . “With the completion of the Seagen acquisition in 2023, Pfizer has significantly expanded its Oncology organization to amplify its efforts to advance new standards of care and improve outcomes for patients,” said Chris Boshoff, Chief Oncology Officer and Executive Vice President, Pfizer. “With the energy of our highly talented colleagues, the tremendous potential of our pipeline and scientific engine, and scale of the Pfizer enterprise, we believe we are poised to deliver on our vision of accelerating breakthroughs that help people with cancer globally live better and longer lives.” Boshoff continued, “We have a clear strategy focused on three core scientific modalities and four main types of cancer, where we have the deep expertise and knowledge to advance our leadership. With many significant catalysts expected through the first half of 2025 and beyond, our Oncology organization is well-positioned to be a critical driver of potential long-term sustainable sales and profit growth for Pfizer through the end of the decade.” During the event, Chris Boshoff and members of the Pfizer Oncology leadership team highlighted the company’s expanded capabilities and portfolio following the completion of the acquisition of Seagen in December 2023. Pfizer Oncology is focused on expanding its leadership in four main cancer types: breast cancer, including three main hormonal subtypes; genitourinary cancer, including prostate and urothelial cancers; hematology-oncology, including multiple myeloma and lymphomas, such as Hodgkin’s disease; and thoracic cancers, which includes lung and head and neck cancers. Pfizer’s Oncology portfolio is focused on three core scientific modalities: small molecules, antibody drug conjugates (ADCs), and bispecific antibodies, including other immuno-oncology biologics. The company is progressing a next-generation ADC platform aimed at novel targets and improved, differentiated payloads, as well as investigational advanced biologics and novel combinations of medicines. The company outlined potential significant catalysts anticipated through the first half of 2025, including: Continued focus on four recent priority indication launches, including PADCEV® (enfortumab vedotin-ejfv) in combination with pembrolizumab in locally advanced / metastatic urothelial cancer; XTANDI® (enzalutamide) in nonmetastatic castration-sensitive prostate cancer (nmCSPC) with biochemical recurrence at high-risk for metastasis; TALZENNA® (talazoparib) in combination with XTANDI in metastatic castration-resistant prostate cancer (mCRPC); and ELREXFIO™ (elranatamab-bcmm) for the treatment of adult patients with relapsed or refractory multiple myeloma who have received at least four prior lines of therapy. Seven anticipated Phase 3 readouts, including results for vepdegestrant in second-line estrogen receptor positive metastatic breast cancer (ER+ mBC) (VERITAC-2), BRAFTOVI® (encorafenib) in first-line BRAF+ metastatic colorectal cancer (BREAKWATER), sasanlimab in non-muscle invasive bladder cancer (CREST), and ELREXFIO in double-class exposed relapsed/refractory multiple myeloma (MagnetisMM-5). Six anticipated Phase 3 study starts, which includes three new trials recently initiated for key pipeline assets: atirmociclib (CDK4i) in second-line hormone receptor positive (HR+) mBC, sigvotatug vedotin (B6A; integrin beta-6 (IB6)-directed ADC) in second/third-line non-small cell lung cancer (NSCLC), and ELREXFIO in patients with multiple myeloma after their cancer progresses on anti-CD38 treatment (MagnetisMM-32 trial). Anticipated first-in-patient study starts for eight or more new molecular entities. During the meeting, Pfizer also shared new or updated clinical data from various pipeline programs, including atirmociclib, ELREXFIO, felmetatug vedotin (B7H4 ADC), mevrometostat (EZH2i), PD-L1 ADC (PF-08046054), and sigvatutag vedotin. Through its strategy, by 2030, the company anticipates 8 or more potential blockbusters and expects biologics to contribute approximately 65% of Oncology revenues, compared to approximately 6% in 2023. Prescribing Information for Pfizer Medicines Please see full Prescribing Information for PADCEV® (enfortumab vedotin). Please see full Prescribing Information for TALZENNA® (talazoparib). Please see full Prescribing Information for XTANDI® (enzalutamide). Please read full Prescribing Information, including BOXED WARNING, for ELREXFIOTM (elranatamab-bcmm). Please see full Prescribing Information for BRAFTOVI® (encorafenib). About Pfizer Oncology At Pfizer Oncology, we are at the forefront of a new era in cancer care. Our industry-leading portfolio and extensive pipeline includes game-changing mechanisms of action to attack cancer from multiple angles, including antibody-drug conjugates (ADCs), small molecules, bispecific antibodies and other immunotherapy biologics. We are focused on delivering transformative therapies in some of the world’s most common cancers, including breast cancer, genitourinary cancer, hematology-oncology, and thoracic cancers, which includes lung cancer. Driven by science, we are committed to accelerating breakthroughs that help people with cancer globally live better and longer lives. About Pfizer: Breakthroughs That Change Patients’ Lives At Pfizer, we apply science and our global resources to bring therapies to people that extend and significantly improve their lives. We strive to set the standard for quality, safety, and value in the discovery, development, and manufacture of health care products, including innovative medicines and vaccines. Every day, Pfizer colleagues work across developed and emerging markets to advance wellness, prevention, treatments, and cures that challenge the most feared diseases of our time. Consistent with our responsibility as one of the world's premier innovative biopharmaceutical companies, we collaborate with health care providers, governments, and local communities to support and expand access to reliable, affordable health care around the world. For more than 175 years, we have worked to make a difference for all who rely on us. We routinely post information that may be important to investors on our website at . In addition, to learn more, please visit us on and follow us on X at @Pfizer and @Pfizer_News, LinkedIn, YouTube and like us on Facebook at Facebook.com/Pfizer. Disclosure Notice The information contained in this release is as of February 29, 2024. The Company assumes no obligation to update forward-looking statements contained in this release as the result of new information or future events or developments. This release contains forward-looking statements about Pfizer Oncology; our anticipated operating and financial performance, including financial guidance and projections; changes to Pfizer’s commercial organization; reorganizations; business plans, strategy, goals and prospects, including our 2030 goals; expectations for our product pipeline, in-line products and product candidates, including anticipated regulatory submissions, data read-outs, study starts, approvals, launches, clinical trial results and other developing data, revenue contribution and projections, potential pricing and reimbursement, potential market dynamics, size and utilization rates, growth, performance, timing of exclusivity and potential benefits; plans for and prospects of our recent acquisition of Seagen and our ability to successfully capitalize on this opportunity; manufacturing and product supply; and other statements about our business, operations and financial results that are subject to substantial risk and uncertainties. Among other things, statements regarding revenue; anticipated operating and financial performance; the development or commercial potential of our product pipeline, in-line products, product candidates and additional indications or combinations, including expected clinical trial protocols, the potential and timing for the initiation and progress of clinical trials and data read-outs from trials; the timing and potential for the submission of applications for and receipt of regulatory approvals; the timing and potential for product launches and commercialization; expected pro labeling; potential revenue; expected breakthrough, best- or first-in-class or blockbuster status or expected market entry of our medicines; potential patients reached; potential portfolio composition; the regulatory landscape; and the competitive landscape are forward-looking and are estimates that are subject to change and subject to, among other risks, assumptions and uncertainties, the uncertainties inherent in research and development, including the ability to meet anticipated clinical endpoints, commencement and/or completion dates for our clinical trials, regulatory submission dates, regulatory approval dates and/or launch dates, as well as the possibility of unfavorable new clinical data and further analyses of existing clinical data; risks associated with interim and preliminary data; the risk that clinical trial data are subject to differing interpretations and assessments by regulatory authorities; whether regulatory authorities will be satisfied with the design of and results from our clinical studies; whether and when any drug applications, biologics license applications and/or emergency use authorization applications may be filed in any jurisdictions for any potential indication for Pfizer’s product candidates; whether and when any such applications that may be filed for any of Pfizer’s product candidates may be approved by regulatory authorities, which will depend on myriad factors, including making a determination as to whether the product's benefits outweigh its known risks and determination of the product's efficacy and, if approved, whether any such product candidates will be commercially successful; decisions by regulatory authorities impacting labeling, manufacturing processes, safety and/or other matters that could affect the availability or commercial potential of Pfizer’s product candidates, including development of products or therapies by other companies; manufacturing capabilities or capacity; uncertainties regarding the ability to obtain recommendations from vaccine technical committees and other public health authorities and uncertainties regarding the commercial impact of any such recommendations; uncertainties regarding the commercial success of Pfizer’s products and product candidates; uncertainties regarding the impact of COVID-19 on Pfizer’s business, operations and financial results; and competitive developments. A further description of risks and uncertainties can be found in Pfizer’s Annual Report on Form 10-K for the fiscal year ended December 31, 2023 and in its subsequent reports on Form 10-Q, including in the sections thereof captioned “Risk Factors” and “Forward-Looking Information and Factors That May Affect Future Results”, as well as in its subsequent reports on Form 8-K, all of which are filed with the U.S. Securities and Exchange Commission and available at and .

Enrollment in dose escalation and backfill cohorts continuing in Phase 1 clinical trial of XMT-1660; expect to initiate tumor-specific expansion cohorts in the second quarter of 2024 and announce initial clinical data in mid-2024Phase 1 clinical trial of XMT-2056 restarting; plan to advance dose escalation in 2024 Continue to expect capital resources will support current operating plan commitments into 2026Conference call today at 8:00 a.m. ET CAMBRIDGE, Mass., Feb. 28, 2024 (GLOBE NEWSWIRE) -- Mersana Therapeutics, Inc. (NASDAQ: MRSN), a clinical-stage biopharmaceutical company focused on discovering and developing a pipeline of antibody-drug conjugates (ADCs) targeting cancers in areas of high unmet medical need, today provided a business update and reported financial results for the fourth quarter and full year ended December 31, 2023. “Mersana’s unwavering commitment to payload and platform innovation has enabled us to enter 2024 with differentiated clinical-stage ADC product candidates, a strong balance sheet and forward momentum,” said Martin Huber, M.D., President and Chief Executive Officer of Mersana Therapeutics. “We have made progress in the dose escalation portion of our Phase 1 clinical trial of XMT-1660 while also enrolling patients in backfill cohorts at multiple clinically relevant dose levels, setting the stage for our planned initial clinical data disclosure for this candidate in mid-2024. Over the course of this year, we also look forward to advancing dose escalation in our Phase 1 clinical trial of XMT-2056 as well as our collaborations with Johnson & Johnson and Merck KGaA.” Mersana’s Strategic Priorities and Expected Milestones XMT-1660: Mersana continues to advance its Phase 1 clinical trial of XMT-1660, the company’s lead Dolasynthen ADC candidate targeting B7-H4. The dose escalation portion of the trial is ongoing, with the company having recently escalated to a dose of 59 milligrams per meter squared. A maximum tolerated dose has not yet been established. In addition to continuing to escalate dosing, the company also is enrolling patients in backfill cohorts to optimize dose and schedule. Mersana plans to initiate tumor-specific expansion cohorts in the second quarter of 2024 and expects to share initial dose escalation and backfill cohort data in mid-2024. XMT-2056: Mersana is restarting its Phase 1 clinical trial of XMT-2056, the company's lead Immunosynthen ADC candidate targeting a novel HER2 epitope. In the fourth quarter, the company announced the lifting of a clinical hold on the Phase 1 clinical trial of XMT-2056 by the U.S. Food and Drug Administration. Mersana plans to advance dose escalation of this wholly owned product candidate in 2024. GSK plc has an exclusive global license option to co-develop and commercialize XMT-2056. Collaborations: Mersana continues to advance its Johnson & Johnson (formerly known as Janssen) and Merck KGaA, Darmstadt, Germany collaborations. The Johnson & Johnson collaboration and license agreement focuses on the discovery of novel Dolasynthen ADCs for up to three targets. The Merck KGaA, Darmstadt, Germany collaboration and license agreement focuses on the discovery of novel Immunosynthen ADCs for up to two targets. Additional Upcoming Data Presentations: At the European Society of Gynaecological Oncology (ESGO) 2024 Congress from March 7-10, 2024 in Barcelona, Spain, clinical data will be presented for Mersana’s two discontinued NaPi2b ADC product candidates: XMT-1536 (UpRi), which was developed using the company’s first-generation Dolaflexin ADC platform, and XMT-1592, which was developed using the company’s next-generation Dolasynthen ADC platform. Fourth Quarter 2023 Financial Results Cash, cash equivalents and marketable securities as of December 31, 2023 were $209.1 million. Mersana continues to expect that its capital resources will be sufficient to support its current operating plan commitments into 2026.Net cash used in operating activities for the fourth quarter of 2023 was $32.0 million. Collaboration revenue for the fourth quarter of 2023 was $10.7 million, compared to $14.7 million for the same period in 2022. The year-over-year change was primarily related to the timing of research activities for the company’s Johnson & Johnson collaboration and achievement of an early Johnson & Johnson development milestone in the fourth quarter of 2022.Research and development (R&D) expenses for the fourth quarter of 2023 were $21.5 million, compared to $45.7 million for the same period in 2022. Included in the fourth quarter of 2023 R&D expenses were $2.2 million in non-cash stock-based compensation expenses and $3.7 million of external costs related to the wind-down of UpRi-related development activities. The year-over-year decline in R&D expenses was primarily related to reduced manufacturing and clinical costs related to UpRi and XMT-2056 and reduced employee compensation costs, partially offset by increased clinical costs related to XMT-1660.General and administrative (G&A) expenses for the fourth quarter of 2023 were $10.1 million, compared to $14.8 million during the same period in 2022. Included in the fourth quarter of 2023 G&A expenses were $1.9 million in non-cash stock-based compensation expenses. The year-over-year decline in G&A expenses was primarily related to reduced consulting and professional services fees and reduced employee compensation as a result of the restructuring plan announced by the company in July 2023.Net loss for the fourth quarter of 2023 was $19.5 million, or $0.16 per share, compared to a net loss of $44.9 million, or $0.44 per share, for the same period in 2022. Full Year 2023 Financial Results Net cash used in operating activities for full year 2023 was $168.9 million.Collaboration revenue for the full year 2023 was $36.9 million, compared to $26.6 million for 2022. The year-over-year increase was primarily related to increased collaboration revenue recognized under the company’s Merck KGaA agreements and early development milestones achieved under its Johnson & Johnson agreement, partially offset by the timing of research activities under the Johnson & Johnson agreement. R&D expenses for the full year 2023 were $148.3 million, compared to $173.4 million for the full year 2022. Included in 2023 R&D expenses were $11.0 million in non-cash stock-based compensation expenses. The decline in R&D expenses was primarily related to reduced manufacturing and clinical costs related to UpRi and XMT-2056 and manufacturing costs for the company’s Dolasynthen platform, partially offset by increased clinical costs related to XMT-1660.G&A expenses for the full year 2023 were $59.5 million, compared to $57.0 million for the full year 2022. Included in 2023 G&A expenses were $10.1 million in non-cash stock-based compensation expenses. The year-over-year change in G&A expenses was primarily related to increased headcount in the first half of 2023 prior to the restructuring that was initiated in July 2023.Mersana incurred $8.7 million in restructuring expenses in the second half of 2023 related primarily to severance-related costs and contract termination expenses.Net loss for the full year 2023 was $171.7 million, or $1.48 per share, compared to a net loss of $204.2 million, or $2.18 per share, for the full year 2022. Conference Call ReminderMersana will host a conference call today at 8:00 a.m. ET to discuss business updates and its financial results for the fourth quarter and full year of 2023. To access the call, please dial 877-270-2148 (domestic) or 412-902-6510 (international). A live webcast of the presentation will be available on the Investors & Media section of the Mersana website at www.mersana.com, and a replay of the webcast will be available in the same location following the conference call for approximately 90 days. About Mersana TherapeuticsMersana Therapeutics is a clinical-stage biopharmaceutical company focused on the development of novel antibody-drug conjugates (ADCs) and driven by the knowledge that patients are waiting for new treatment options. The company has developed proprietary cytotoxic (Dolasynthen) and immunostimulatory (Immunosynthen) ADC platforms that are generating a pipeline of wholly-owned and partnered product candidates with the potential to treat a range of cancers. Its pipeline includes XMT-1660, a Dolasynthen ADC targeting B7-H4, and XMT-2056, an Immunosynthen ADC targeting a novel epitope of human epidermal growth factor receptor 2 (HER2). Mersana routinely posts information that may be useful to investors on the “Investors & Media” section of its website at www.mersana.com. Forward-Looking StatementsThis press release contains “forward-looking” statements and information within the meaning of the Private Securities Litigation Reform Act of 1995. These statements may be identified by words such as “aims,” “anticipates,” “believes,” “could,” “estimates,” “expects,” “forecasts,” “goal,” “intends,” “may,” “plans,” “possible,” “potential,” “seeks,” “will” and variations of these words or similar expressions, although not all forward-looking statements contain these words. Forward-looking statements in this press release include, but are not limited to, statements concerning Mersana’s strategic priorities; its plans regarding the clinical development of XMT-1660 and XMT-2056, including with respect to the resumption of Mersana’s Phase 1 clinical trial of XMT-2056 and the progress and design of the clinical trials of these product candidates; Mersana’s planned data presentations, including with respect to its Phase 1 clinical trial of XMT-1660; Mersana’s cash runway; Mersana’s collaborations with third parties; and the development and potential of Mersana’s product candidates, platforms, technology and pipeline of ADC candidates. Mersana may not actually achieve the plans, intentions or expectations disclosed in these forward-looking statements, and you should not place undue reliance on these forward-looking statements. Actual results or events could differ materially from the plans, intentions and expectations disclosed in these forward-looking statements as a result of various factors, including, among other things, uncertainties inherent in research and development, in the advancement, progression and completion of clinical trials and in the clinical development of Mersana’s product candidates, including XMT-1660 and XMT-2056; the risk that Mersana may face delays in resuming its Phase 1 clinical trial of XMT-2056; the risk that Mersana may not realize the intended benefits of its platforms, technology and collaborations; and other important factors, any of which could cause Mersana’s actual results to differ from those contained in the forward-looking statements, that are described in greater detail in the section entitled “Risk Factors” in Mersana’s Quarterly Report on Form 10-Q filed with the Securities and Exchange Commission (“SEC”) on November 7, 2023, as well as in other filings Mersana may make with the SEC in the future. Any forward-looking statements contained in this press release speak only as of the date hereof, and Mersana expressly disclaims any obligation to update any forward-looking statements contained herein, whether because of any new information, future events, changed circumstances or otherwise, except as otherwise required by law. Mersana Therapeutics, Inc.Selected Condensed Consolidated Balance Sheet Data(in thousands and unaudited) December 31,2023 December 31,2022 Cash, cash equivalents and marketable securities$209,084 $280,712Working capital(1) 150,420 227,686Total assets 226,060 334,340Total stockholders' equity 36,904 92,057 (1) The company defines working capital as current assets less current liabilities. Mersana Therapeutics, Inc.Condensed Consolidated Statement of Operations(in thousands, except share and per share data, and unaudited) Three months ended Year ended December 31,2023 December 31,2022 December 31,2023 December 31,2022 Collaboration revenue$10,701 $14,688 $36,855 $26,581 Operating expenses: Research and development 21,495 45,709 148,269 173,385 General and administrative 10,134 14,805 59,543 56,963 Restructuring expenses 499 — 8,713 — Total operating expenses 32,128 60,514 216,525 230,348 Total other income (expense), net 1,883 902 8,000 (445)Net loss$(19,544) $(44,924) $(171,670) $(204,212)Net loss per share — basic and diluted$(0.16) $(0.44) $(1.48) $(2.18)Weighted-average number of common shares — basic and diluted 120,614,350 101,014,142 116,112,891 93,654,243 Contact:Jason Fredette617-498-0020jason.fredette@mersana.com

CAMBRIDGE, Mass., Feb. 27, 2024 (GLOBE NEWSWIRE) -- Mersana Therapeutics, Inc. (NASDAQ: MRSN), a clinical-stage biopharmaceutical company focused on discovering and developing a pipeline of antibody-drug conjugates (ADCs) targeting cancers in areas of high unmet medical need, today announced that members of management will present at the following upcoming investor conferences: TD Cowen 44th Annual Health Care Conference Format:Panel discussionDate/Time:Tuesday, March 5, 2024, at 9:10 a.m. Eastern Time Leerink Global Biopharma Conference Format:Fireside chatDate/Time:Tuesday, March 12, 2024, at 8:40 a.m. Eastern Time Live webcasts of these events will be available on the Investors & Media section of Mersana’s website at www.mersana.com. Archived replays will be available for approximately 90 days following the events. About Mersana TherapeuticsMersana Therapeutics is a clinical-stage biopharmaceutical company focused on the development of novel antibody-drug conjugates (ADCs) and driven by the knowledge that patients are waiting for new treatment options. The company has developed proprietary cytotoxic (Dolasynthen) and immunostimulatory (Immunosynthen) ADC platforms that are generating a pipeline of wholly-owned and partnered product candidates with the potential to treat a range of cancers. Its pipeline includes XMT-1660, a Dolasynthen ADC targeting B7-H4, and XMT-2056, an Immunosynthen ADC targeting a novel epitope of human epidermal growth factor receptor 2 (HER2). Mersana routinely posts information that may be useful to investors on the “Investors & Media” section of its website at www.mersana.com. Contact:Jason Fredette617-498-0020jason.fredette@mersana.com