Mersana Therapeutics, Inc.

CAMBRIDGE, Mass., April 23, 2025 (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 the following presentations related to emiltatug ledadotin (Emi-Le; XMT-1660), Mersana’s B7-H4-directed Dolasynthen ADC, will be given at the American Society of Clinical Oncology (ASCO) 2025 Annual Meeting taking place May 30-June 3, 2025 at McCormick Place, Chicago, IL: Oral Presentation Details Title: Initial Phase 1 Dose Escalation Data for Emiltatug Ledadotin (Emi-Le), a Novel B7-H4-Directed Dolasynthen Antibody-Drug Conjugate Rapid Oral Session Title: Developmental Therapeutics Date and Time: Monday, June 2, 2025 from 8:00-9:30 a.m. CT Abstract Number: 3009 Presenter: Erika Hamilton, M.D., Director Breast Cancer Research Program, Sarah Cannon Research Institute in Nashville, Tennessee This presentation will include clinical data from dose escalation and backfill cohorts across tumor types from the ongoing Phase 1 clinical trial of Emi-Le. Poster Presentation Details Title: Emiltatug Ledadotin (Emi-Le): A B7-H4-Directed Dolasynthen Antibody-Drug Conjugate (ADC) Being Investigated in Phase 1 Dose Expansion in Patients with Triple Negative Breast Cancer Who Received at Least One Prior Topoisomerase-1 Inhibitor ADC Poster Session Title: Breast Cancer - Metastatic Date and Time: Monday, June 2, 2025 from 9:00-12:00 p.m. CT Abstract Number: TPS1141 Presenter: Hyo Han, M.D., H. Lee Moffitt Cancer Center and Research Institute, Tampa, Florida This “trial-in-progress” presentation will focus on the design of the ongoing expansion portion of Mersana’s Phase 1 clinical trial of Emi-Le that is actively enrolling patients with triple negative breast cancer (TNBC) who have received one to four prior treatment lines, including at least one topoisomerase-1 inhibitor ADC. Additionally, as previously announced, an oral presentation regarding Emi-Le will be given at the ESMO Breast Cancer 2025 Annual Congress in Munich, Germany on Thursday, May 15, 2025. This presentation will focus on TNBC clinical data from dose escalation and backfill cohorts from the Phase 1 clinical trial of Emi-Le. About Emi-Le Emi-Le is a B7-H4-directed Dolasynthen ADC with a precise, target-optimized drug-to-antibody ratio (DAR 6) and a proprietary auristatin payload with controlled bystander effect. This candidate is being investigated in a Phase 1 dose escalation and expansion trial in patients with solid tumors, including breast, endometrial and ovarian cancers as well as adenoid cystic carcinoma type 1. In the initial clinical data that were reported as of a December 13, 2024 data cutoff, Emi-Le was observed to be generally well tolerated with differentiated safety and tolerability profile. Additionally, confirmed objective responses were observed across all enrolled tumor types, including in patients with triple negative breast cancer (TNBC) who had previously been treated with a topoisomerase-1 inhibitor (topo-1) ADC. The U.S. Food and Drug Administration has granted two Fast Track designations to Emi-Le for the treatment of 1) adult patients with advanced or metastatic triple-negative breast cancer, and 2) advanced or metastatic breast cancer in patients with human epidermal growth factor receptor 2 (HER2) low (IHC 1+ or IHC 2+/ISH–) or HER2-negative (IHC 0) disease, including TNBC, who have received a prior topo-1 ADC. For more information about Mersana’s ongoing Phase 1 trial of Emi-Le, please visit clinicaltrials.gov (NCT05377996). About Mersana Therapeutics Mersana 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 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). Mersana routinely posts information that may be useful to investors on the “Investors & Media” section of its website at www.mersana.com. Contact: Jason Fredette 617-498-0020 jason.fredette@mersana.com

CAMBRIDGE, Mass., April 01, 2025 (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 Phase 1 dose escalation and backfill cohort clinical data for emiltatug ledadotin (Emi-Le; XMT-1660) will be presented in an oral session at the ESMO Breast Cancer 2025 Annual Congress, which is being held from May 14-17, 2025, in Munich, Germany. Oral Presentation Details Title: Clinical Activity of Emiltatug Ledadotin (Emi-Le), a B7-H4-Directed ADC, in Patients with TNBC who Received at Least One Prior Topoisomerase-1 Inhibitor (Topo-1) ADC Session Title: Mini Oral Session 1 Date and Time: Thursday, May 15, 2025 from 8:30-10:00 a.m. CEST Abstract Number: 298MO Presenter: Erika Hamilton, M.D., Director Breast Cancer Research, Sarah Cannon Research Institute in Nashville, Tennessee About Emi-Le Emi-Le is a B7-H4-directed Dolasynthen ADC with a precise, target-optimized drug-to-antibody ratio (DAR 6) and a proprietary auristatin payload with controlled bystander effect. This candidate is being investigated in a Phase 1 dose escalation and expansion trial in patients with solid tumors, including breast, endometrial and ovarian cancers as well as adenoid cystic carcinoma type 1. In the initial clinical data that were reported as of a December 13, 2024 data cutoff, Emi-Le was observed to be generally well tolerated with differentiated safety and tolerability profile. Additionally, confirmed objective responses were observed across all enrolled tumor types, including in patients with triple negative breast cancer (TNBC) who had previously been treated with a topoisomerase-1 inhibitor (topo-1) ADC. The U.S. Food and Drug Administration has granted two Fast Track designations to Emi-Le for the treatment of 1) adult patients with advanced or metastatic triple-negative breast cancer, and 2) advanced or metastatic breast cancer in patients with human epidermal growth factor receptor 2 (HER2) low (IHC 1+ or IHC 2+/ISH–) or HER2-negative (IHC 0) disease, including TNBC, who have received a prior topo-1 ADC. For more information about Mersana’s ongoing Phase 1 trial of Emi-Le, please visit clinicaltrials.gov (NCT05377996). About Mersana Therapeutics Mersana 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 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). Mersana routinely posts information that may be useful to investors on the “Investors & Media” section of its website at www.mersana.com. Contact: Jason Fredette 617-498-0020 jason.fredette@mersana.com

Pfizer’s pipeline prioritization has now turned to a STING agonist, with an early-stage study termination of the asset, a spokesperson confirmed to Endpoints News . The company ended a Phase 1 trial of its STING agonist PF-07820435 “due to business strategy and not for safety concern with study drug,” the spokesperson said in a Thursday afternoon email. The asset remained in Pfizer’s pipeline as recently as last month’s quarterly update. The New York drug giant was testing the candidate alone and in combination with its late-stage anti-PD-1 monoclonal antibody called sasanlimab. The study enrolled nine patients with advanced solid tumors, according to an update to the US federal trials database this week. Pfizer originally planned to bring 140 patients into the trial, according to a historical record of the study. PF-07820435 was orally delivered, whereas other STING agonists in development have been delivered via other mechanisms, including antibody-drug conjugates (like at Mersana Therapeutics ) and IV-infused candidates (including at Takeda ). Pfizer has revised its pipeline multiple times in recent quarters as it undergoes billions of dollars in cost cuts, and as its new R&D and medical leadership team settle into place .