Emi-Le (XMT-1660) Clinical Development - Mersana is advancing Emi-Le to address the high unmet need in post-Topo-1 TNBC, with over 40 patients enrolled in the expansion phase at two doses and plans to present initial expansion data in the second half of 2025[5] - Confirmed objective responses were observed across various tumor types including HR+BC, endometrial cancer, ovarian cancer, and ACC-1[5] - In the intermediate dose range, an ORR of 31% (8/26) was observed in evaluable patients with B7-H4 high tumors, including a 23% (3/13) ORR in TNBC and a 50% (2/4) ORR in endometrial cancer[55] - In evaluable patients with B7-H4 high post-Topo-1 TNBC in the intermediate dose range, the confirmed ORR was 23% (3/13), and 29% (2/7) in patients with ≤4 prior lines of therapy[58] - Preliminary data in the high dose range suggest potential for even greater clinical activity, with 7 out of 11 evaluable patients achieving tumor reductions of ≥30% at doses >674 mg/m2[67] XMT-2056 and Platform Collaborations - XMT-2056, an Immunosynthen STING agonist HER2 ADC, is in Phase 1 dose escalation, with plans to present initial clinical pharmacodynamic STING activation data in 2025[5] - Mersana has a global license option agreement with GSK plc for XMT-2056[5] - Mersana has a Dolasynthen research collaboration with Johnson & Johnson and an Immunosynthen research collaboration with Merck KGaA, Darmstadt, Germany[5] Safety and Tolerability - Emi-Le was observed to be generally well-tolerated, with any treatment-related adverse event (TRAE) occurring in 830% (117/141) of patients, Grade 3 TRAEs in 369% (52/141), and TRAEs leading to treatment discontinuation in 35% (5/141)[43] - The most common TRAEs were transient AST increase, generally asymptomatic and reversible proteinuria, generally low-grade fatigue and nausea[47] Market Opportunity - The global relapsed/refractory TNBC market is projected to exceed $1 billion annually starting in 2025[28] ACC-1 Clinical Activity - In patients with ACC-1, the ORR was 556% (5/9) across all doses, unselected for B7-H4 expression[94]

[Business Update and Q2 2025 Financial Results](index=1&type=section&id=Mersana%20Therapeutics%20Provides%20Business%20Update%20and%20Announces%20Second%20Quarter%202025%20Financial%20Results) Mersana Therapeutics provided a comprehensive business update, highlighting clinical progress for Emi-Le and XMT-2056, corporate actions like a reverse stock split, and detailed Q2 2025 financial performance [Business and Pipeline Update](index=1&type=section&id=Business%20and%20Pipeline%20Update) Mersana Therapeutics reported encouraging clinical data for its lead ADC, Emi-Le, and advanced its Phase 1 dose expansion, while XMT-2056 progressed and a $15 million GSK milestone was achieved [Emiltatug Ledadotin (Emi-Le; XMT-1660)](index=1&type=section&id=Emiltatug%20Ledadotin%20(Emi-Le%3B%20XMT-1660)) The company presented positive clinical data for Emi-Le, its B7-H4-directed ADC, at ASCO 2025 and ESMO Breast Cancer 2025, highlighting its activity in patients with TNBC and ACC-1, with initial data from the Phase 1 dose expansion trial anticipated in the second half of 2025 - Encouraging clinical data for Emi-Le was presented in oral sessions at both ASCO 2025 and ESMO Breast Cancer 2025, showing activity in patients with post-topo-1 TNBC and adenoid cystic carcinoma type 1 (ACC-1)[3](index=3&type=chunk)[5](index=5&type=chunk) - The Phase 1 dose expansion has enrolled over **45 patients** with TNBC across two cohorts[6](index=6&type=chunk)[7](index=7&type=chunk)[8](index=8&type=chunk) - Mersana plans to report initial clinical data from these expansion cohorts in the **second half of 2025**[3](index=3&type=chunk)[6](index=6&type=chunk)[8](index=8&type=chunk) [XMT-2056](index=2&type=section&id=XMT-2056) The Phase 1 dose escalation for XMT-2056, a HER2-targeting Immunosynthen ADC, is ongoing, with Mersana achieving a $15 million development milestone from GSK and expecting initial clinical pharmacodynamic STING activation data in the second half of 2025 - The dose escalation portion of the Phase 1 clinical trial for XMT-2056, targeting a novel HER2 epitope, is currently ongoing[9](index=9&type=chunk) - In July 2025, Mersana achieved a **$15 million** development milestone under its agreement with GSK, with payment due in **Q3 2025**[9](index=9&type=chunk) - Initial clinical pharmacodynamic STING activation data for XMT-2056 is expected to be presented in the **second half of 2025**[9](index=9&type=chunk) [Collaborations](index=2&type=section&id=Collaborations) The company continues to support its ongoing research collaborations with Johnson & Johnson for the Dolasynthen platform and with Merck KGaA, Darmstadt, Germany for the Immunosynthen platform - Mersana continues to support its Dolasynthen research collaboration with Johnson & Johnson and its Immunosynthen research collaboration with Merck KGaA, Darmstadt, Germany[10](index=10&type=chunk) [Corporate Developments](index=2&type=section&id=Corporate%20Developments) Mersana executed a 1-for-25 reverse stock split in late July 2025, which successfully reduced the number of outstanding shares and led to regaining compliance with Nasdaq's minimum bid price requirement in August 2025 - A **1-for-25 reverse stock split** became effective on July 25, 2025, reducing outstanding common stock from approximately **124.8 million shares to 5.0 million shares**[11](index=11&type=chunk) - On August 11, 2025, the company received formal notification from Nasdaq confirming it had regained compliance with the minimum bid price requirement[12](index=12&type=chunk) [Second Quarter 2025 Financial Results](index=2&type=section&id=Second%20Quarter%202025%20Financial%20Results) For Q2 2025, Mersana reported a net loss of $24.3 million, nearly identical to the prior year, with increased collaboration revenue, decreased R&D and G&A expenses, and $77.0 million in cash and cash equivalents expected to fund operations into mid-2026 - Cash and cash equivalents were **$77.0 million** as of June 30, 2025, with capital resources expected to fund operations into **mid-2026**[13](index=13&type=chunk) Second Quarter 2025 Key Financials | Financial Metric | Q2 2025 (in millions) | Q2 2024 (in millions) | | :--- | :--- | :--- | | Collaboration Revenue | $3.1 | $2.3 | | R&D Expense | $16.2 | $17.2 | | G&A Expense | $7.4 | $10.5 | | Restructuring Expenses | $3.9 | $0 | | Net Loss | $(24.3) | $(24.3) | | Net Loss Per Share | $(4.87) | $(4.96) | - The decrease in R&D and G&A expenses was primarily related to lower headcount and related employee compensation costs[16](index=16&type=chunk) [Financial Statements](index=5&type=section&id=Financial%20Statements) The condensed consolidated financial statements detail Mersana's financial position as of June 30, 2025, and operational results for the three and six months then ended, including cash, assets, liabilities, and net loss [Selected Condensed Consolidated Balance Sheet Data](index=5&type=section&id=Selected%20Condensed%20Consolidated%20Balance%20Sheet%20Data) As of June 30, 2025, Mersana had $77.0 million in cash, cash equivalents, and marketable securities, a decrease from year-end 2024, with total assets at $84.6 million, total liabilities at $137.7 million, and a total stockholders' deficit of $53.1 million Selected Condensed Consolidated Balance Sheet Data | (in thousands) | June 30, 2025 | December 31, 2024 | | :--- | :--- | :--- | | Cash, cash equivalents and marketable securities | $76,972 | $134,620 | | Total assets | $84,573 | $144,663 | | Total liabilities | $137,719 | $154,172 | | Total stockholders' deficit | $(53,146) | $(9,509) | [Condensed Consolidated Statement of Operations](index=5&type=section&id=Condensed%20Consolidated%20Statement%20of%20Operations) For the three months ended June 30, 2025, Mersana reported collaboration revenue of $3.1 million and total operating expenses of $27.6 million, resulting in a net loss of $24.3 million, or $4.87 per share, comparable to the prior year Condensed Consolidated Statement of Operations | (in thousands, except per share data) | Three months ended June 30, 2025 | Three months ended June 30, 2024 | | :--- | :--- | :--- | | Collaboration revenue | $3,056 | $2,293 | | Research and development | $16,218 | $17,245 | | General and administrative | $7,415 | $10,503 | | Restructuring expenses | $3,940 | - | | **Total operating expenses** | **$27,573** | **$27,748** | | **Net loss** | **$(24,296)** | **$(24,268)** | | **Net loss per share — basic and diluted** | **$(4.87)** | **$(4.96)** |

Core Viewpoint - Mersana Therapeutics is making significant progress in the development of its antibody-drug conjugates (ADCs), particularly Emi-Le, with promising clinical data presented at major oncology conferences and ongoing patient enrollment in clinical trials [2][4][5]. Clinical Development - The company presented clinical data for Emi-Le at ASCO 2025 and ESMO Breast Cancer 2025, showcasing its activity in triple-negative breast cancer (TNBC) and adenoid cystic carcinoma type 1 (ACC-1) [2][4]. - Mersana is currently enrolling patients in two dose expansion cohorts for Emi-Le, with over 45 patients enrolled so far, and plans to report initial clinical data in the second half of 2025 [5][8]. Financial Performance - For Q2 2025, Mersana reported collaboration revenue of $3.1 million, an increase from $2.3 million in Q2 2024, attributed to higher revenue from partnerships with Johnson & Johnson and Merck KGaA [15][20]. - The company incurred a net loss of $24.3 million for Q2 2025, consistent with the loss of $24.3 million in Q2 2024, with a net loss per share of $4.87 compared to $4.96 in the prior year [15][20]. Cash Position - As of June 30, 2025, Mersana had cash and cash equivalents of $77.0 million, down from $134.6 million at the end of 2024 [15][18]. - The company expects its capital resources to support its operating plan commitments into mid-2026 [15]. Corporate Actions - Mersana executed a 1-for-25 reverse stock split on July 25, 2025, reducing the number of outstanding shares from approximately 124.8 million to about 5.0 million [8][10]. - The company regained compliance with Nasdaq's minimum bid price requirement as of August 11, 2025, following a closing bid price of at least $1.00 for 10 consecutive business days [11]. Collaborations - Mersana continues to advance its collaborations with Johnson & Johnson and Merck KGaA, focusing on research related to its Dolasynthen and Immunosynthen ADC platforms [7].

Company Overview - Mersana Therapeutics, Inc. is a clinical-stage biopharmaceutical company focused on developing antibody-drug conjugates (ADCs) targeting cancers with high unmet medical needs [3] - The company has proprietary platforms for cytotoxic (Dolasynthen) and immunostimulatory (Immunosynthen) ADCs, leading to a pipeline of product candidates [3] Pipeline and Product Candidates - Mersana's pipeline includes Emi-Le (emiltatug ledadotin; 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) [3] Upcoming Financial Updates - Mersana Therapeutics will provide business updates and report its financial results for the second quarter ended June 30, 2025, on August 13, 2025 [1] - A conference call and webcast will be held at 8:00 a.m. Eastern Time on the same day [1]

Core Points - Mersana Therapeutics, Inc. announced a 1-for-25 reverse stock split effective July 25, 2025, aimed at increasing the per-share market price to comply with Nasdaq listing requirements [1][2] - The reverse stock split will reduce the number of outstanding shares from approximately 124.8 million to about 5.0 million, without changing the number of authorized shares or par value [4] - The company's common stock will begin trading on a split-adjusted basis on July 28, 2025, under the existing ticker "MRSN" [3] Company Overview - Mersana Therapeutics is a clinical-stage biopharmaceutical company focused on developing antibody-drug conjugates (ADCs) for cancer treatment, addressing high unmet medical needs [1][8] - The company has proprietary ADC platforms, including Dolasynthen and Immunosynthen, with a pipeline of product candidates targeting various cancers [8] - Notable candidates in the pipeline include Emi-Le (emiltatug ledadotin) targeting B7-H4 and XMT-2056 targeting a novel epitope of HER2 [8]

Core Viewpoint - Mersana Therapeutics announced additional interim Phase 1 clinical data for emiltatug ledadotin (Emi-Le), a B7-H4-directed Dolasynthen ADC, at the ASCO 2025 Annual Meeting, highlighting its potential in treating cancers with high unmet medical need [1][3][4] Group 1: Clinical Data and Results - The presentation focused on Emi-Le's Phase 1 dose escalation and backfill cohorts for patients with triple-negative breast cancer (TNBC), hormone-receptor-positive, HER2-negative breast cancer, ovarian cancer, endometrial cancer, and adenoid cystic carcinoma type 1 (ACC-1) [2] - The confirmed objective response rate (ORR) was 31% (8 responses in 26 evaluable patients) across all enrolled tumor types with high B7-H4 expression [6][7] - In patients with ≤4 prior lines of therapy, the confirmed ORR was 44% (7 responses in 16 evaluable patients) [6][7] - For ACC-1 patients, the ORR was 56% (5 responses in 9 patients), with median progression-free survival (PFS) not yet reached [7] Group 2: Safety and Tolerability - Safety and tolerability data as of March 8, 2025, were consistent with earlier reports, showing no new safety signals [3][4] - The safety profile of Emi-Le appears differentiated from many other ADCs, particularly in late-stage TNBC and ACC-1 patients [4] Group 3: Regulatory Designations and Development Potential - The U.S. FDA granted two Fast Track designations to Emi-Le for treating advanced or metastatic TNBC and advanced or metastatic HER2 low/HER2 negative breast cancer post-topo-1 ADC [8] - The company is focusing initial expansion work on TNBC patients previously treated with topoisomerase-1 inhibitor ADCs, indicating a strategic direction in addressing high unmet needs [3][5] Group 4: Company Overview - Mersana Therapeutics is a clinical-stage biopharmaceutical company developing novel ADCs, with a pipeline that includes Emi-Le and XMT-2056, targeting various cancers [9] - The company emphasizes the urgency for new treatment options for patients, driven by its proprietary ADC platforms [9]

Summary of Mersana Therapeutics Conference Call Company Overview - **Company**: Mersana Therapeutics - **Event**: Sixth Annual Oncology Innovation Summit - **Key Participants**: Marty Huber (President and CEO), Brian Deschuytner (COO and CFO) Core Industry Insights - **Industry**: Biotechnology, specifically focused on oncology and antibody-drug conjugates (ADCs) Key Points and Arguments Data Updates and Efficacy - Mersana has provided updates on their phase one data for EMILI, an ADC targeting b7-H4, showing a differentiated safety profile with effective doses and minimal side effects like neutropenia and neuropathy [4][5] - The overall response rate (ORR) for EMILI has improved from 23% to 31% across all tumor types, indicating compelling efficacy, particularly in triple-negative breast cancer (TNBC) patients who are late-line and highly refractory [5][6] - The company is focusing on the unmet need in patients who have previously received topoisomerase (topo) inhibitors, where the response rate is typically low [6][7] Regulatory Designations - Mersana has received fast track designations for EMILI in TNBC and certain breast cancer patients post-topo, indicating regulatory recognition of the unmet need in this area [7] Upcoming Presentations - The ASCO presentation will provide additional follow-up data from the ESMO breast presentation, focusing on all enrolled tumor types and more details on non-breast cancer patients [9][10] Patient Management and Protocol Adjustments - The company has implemented protocol amendments to mitigate proteinuria, a treatment-related adverse event, allowing for continued dosing in asymptomatic patients [13][17] - Early feedback from physicians indicates satisfaction with the new protocol, as it allows for better management of patients who are responding well to treatment [17][18] Dose Expansion Strategy - Mersana is exploring high-dose regimens, with a focus on increasing exposure while managing side effects. The rationale for dose selection is based on observed tumor reductions in initial datasets [25][26] - The company aims to confirm initial responses and improve the overall response rate by avoiding treatment interruptions due to adverse events [31][32] Patient Population and Biomarkers - The target population for dose expansion includes TNBC patients with prior chemotherapy, particularly those who have received at least one prior ADC [34][36] - Mersana is using a consistent assay for b7-H4 expression across different study phases, which is crucial for identifying the appropriate patient population [37][38] Trial Design Considerations - Mersana is considering a randomized pivotal trial rather than a single-arm study, as randomized trials are preferred by regulatory agencies and provide critical control data [42][45] - The company aims for a minimum response rate of 20% in the pivotal trial, significantly higher than the 5% response rate observed in control arms of previous studies [46] Additional Important Insights - The company is aware of the challenges in enrolling patients who have previously received topo inhibitors, as many investigators are hesitant to include these patients due to the lack of consistent clinical benefits [40][41] - Mersana's approach to managing adverse events and optimizing dosing schedules reflects a commitment to improving patient outcomes in a challenging therapeutic area [18][25]

Core Insights - Mersana Therapeutics, Inc. provided a business update and reported financial results for Q1 2025, focusing on the development of its antibody-drug conjugates (ADCs) targeting cancers with high unmet medical needs [2][15]. Business Update - The company is advancing the development of Emi-Le, a B7-H4-directed Dolasynthen ADC, with promising preliminary data presented at ESMO Breast Cancer 2025 [3][4]. - Encouraging clinical activity data showed an objective response rate (ORR) of 31% among evaluable patients with B7-H4 high tumors receiving intermediate doses of Emi-Le, an increase from 23% previously reported [5][7]. - The focus remains on triple-negative breast cancer (TNBC) patients, with ongoing enrollment in dose expansion cohorts [6][10]. Clinical Data - Updated clinical data from Emi-Le's Phase 1 trial indicated a median progression-free survival (PFS) of 16.0 weeks and a median overall survival (OS) of 5.7 months for patients with B7-H4 low TNBC [8]. - The company plans to report initial clinical data from the expansion portion of its Phase 1 trial in the second half of 2025 [11]. Financial Results - As of March 31, 2025, Mersana had cash and cash equivalents of $102.3 million, with net cash used in operating activities amounting to $29.3 million for Q1 2025 [15][20]. - Collaboration revenue for Q1 2025 was $2.8 million, a decrease from $9.2 million in the same period in 2024, primarily due to reduced revenue from collaboration agreements [15][16]. - The net loss for Q1 2025 was $24.1 million, or $0.19 per share, compared to a net loss of $19.3 million, or $0.16 per share, for the same period in 2024 [20][25]. Future Plans - Mersana is set to present at the American Society of Clinical Oncology (ASCO) 2025 Annual Meeting, with two presentations regarding Emi-Le planned [12]. - The company continues to support collaborations with Johnson & Johnson and Merck KGaA, focusing on the development of its ADC platforms [14].

Company Performance - Mersana Therapeutics reported a quarterly loss of $0.19 per share, which was better than the Zacks Consensus Estimate of a loss of $0.21, but worse than the loss of $0.16 per share from the previous year, indicating a 18.75% increase in loss year-over-year [1] - The company achieved an earnings surprise of 9.52% for the quarter, having previously posted a loss of $0.11 per share against an expected loss of $0.16 per share, resulting in a surprise of 31.25% [1][2] - Over the last four quarters, Mersana has surpassed consensus EPS estimates three times [2] Revenue Analysis - Mersana's revenues for the quarter ended March 2025 were $2.75 million, which missed the Zacks Consensus Estimate by 62.78% and represented a significant decline from $9.25 million in the same quarter last year [2] - The company has topped consensus revenue estimates two times over the last four quarters [2] Stock Performance and Outlook - Mersana Therapeutics shares have declined approximately 73.4% since the beginning of the year, contrasting with the S&P 500's gain of 0.2% [3] - The company's future stock performance will largely depend on management's commentary during the earnings call and the sustainability of earnings expectations [3][4] Earnings Estimates - The current consensus EPS estimate for the upcoming quarter is -$0.20, with expected revenues of $7.4 million, and for the current fiscal year, the estimate is -$0.68 on revenues of $35.38 million [7] - The trend for estimate revisions ahead of the earnings release has been favorable, leading to a Zacks Rank 2 (Buy) for the stock, suggesting it is expected to outperform the market in the near future [6] Industry Context - Mersana operates within the Medical - Biomedical and Genetics industry, which is currently ranked in the top 28% of over 250 Zacks industries, indicating a favorable industry outlook [8] - The performance of Mersana's stock may also be influenced by the overall outlook for the industry, as top-ranked industries tend to outperform lower-ranked ones significantly [8]

Financial Performance - The company reported net losses of $24.1 million for Q1 2025, compared to $19.3 million for Q1 2024, with an accumulated deficit of $919.7 million as of March 31, 2025[151]. - Collaboration revenue decreased by $6.5 million, from $9.2 million for the three months ended March 31, 2024 to $2.8 million for the three months ended March 31, 2025[172]. - Net loss increased by $4.8 million, from $19.3 million for the three months ended March 31, 2024 to $24.1 million for the same period in 2025[171]. - Net cash used in operating activities was $29.3 million for the three months ended March 31, 2025, compared to $32.7 million for the same period in 2024[181]. - Total operating expenses decreased by $2.98 million, from $30.2 million for the three months ended March 31, 2024 to $27.3 million for the same period in 2025[171]. - Research and development expenses totaled $18.3 million for the three months ended March 31, 2025, a decrease of $0.3 million from $18.7 million in the same period of 2024[173]. - General and administrative expenses decreased by $2.6 million, from $11.6 million for the three months ended March 31, 2024 to $8.9 million for the same period in 2025[175]. Cash Position - As of March 31, 2025, the company had cash and cash equivalents of $102.3 million, which is expected to fund operations into mid-2026[151]. - Net cash provided by investing activities was $27.0 million in Q1 2025, a significant improvement from net cash used of $72.5 million in Q1 2024, primarily due to maturities of marketable securities[183]. - Net cash used in financing activities was $3.1 million in Q1 2025, down from net cash provided of $5.8 million in Q1 2024, mainly due to debt principal payments[184]. - The company anticipates increased cash expenditures related to ongoing development, clinical trials, and potential commercialization of product candidates[185]. - As of March 31, 2025, the company has borrowed $25.0 million under the New Credit Facility, with $5.2 million of principal repaid[180]. - The company may need to raise additional funds through equity offerings, debt financings, or strategic collaborations, with no assurance of success in obtaining sufficient funding[186][189]. Clinical Development - The ongoing Phase 1 clinical trial of Emi-Le has shown a confirmed objective response rate (ORR) of 31% among evaluable patients with "B7-H4 high" tumor expression, an increase from the previous 23% reported[144]. - The company plans to report initial clinical data from the expansion portion of the Phase 1 trial of Emi-Le in the second half of 2025[145]. - The company is currently enrolling patients in the dose escalation portion of the Phase 1 trial of XMT-2056, with initial pharmacodynamic data expected in 2025[145]. - The company has entered into a global collaboration with GSK for the co-development and commercialization of XMT-2056, which targets a novel HER2 epitope[149]. - The company is focusing on advancing the clinical development of Emi-Le and XMT-2056 while reducing research activities and internal pipeline development efforts[146]. Restructuring and Cost Management - The company has implemented a strategic restructuring plan, reducing approximately 55% of its employee base, expected to be completed by Q3 2025, incurring estimated costs of $4-5 million[146][147]. - The company has discontinued the development of upifitimab rilsodotin (XMT-1536) and completed the related restructuring by December 31, 2023[148]. - Significant external costs for manufacturing and clinical trials are incurred, with total research and development costs at $18.3 million for the three months ended March 31, 2025[162]. - The company expects to incur significant research and development expenses over the next several years as it continues clinical development and manufacturing efforts[166]. Market and Risk Factors - The interest rate on the New Credit Facility is sensitive to changes, with a principal balance of $19.8 million outstanding as of March 31, 2025[195]. - The company is exposed to market risk related to interest rates, but believes that a 100 basis points change would not materially affect the fair market value of its investment portfolio[194]. - There were no material changes to contractual obligations during the three months ended March 31, 2025[192].