Mersana Therapeutics Announces Upcoming Emi-Le Oral and Poster Presentations at ASCO 2025 Annual Meeting

Rhea-AI Summary

Mersana Therapeutics (NASDAQ: MRSN) announced upcoming presentations of their B7-H4-directed Dolasynthen ADC, emiltatug ledadotin (Emi-Le), at the ASCO 2025 Annual Meeting from May 30-June 3, 2025. The presentations include:

1. An oral presentation on Phase 1 dose escalation data across tumor types by Dr. Erika Hamilton on June 2, 2025

2. A poster presentation on the ongoing Phase 1 dose expansion trial in triple negative breast cancer (TNBC) patients by Dr. Hyo Han

Initial clinical data from December 2024 showed Emi-Le was generally well tolerated with confirmed objective responses across all enrolled tumor types. The FDA has granted two Fast Track designations for Emi-Le: one for advanced/metastatic TNBC and another for HER2 low/negative breast cancer patients who received prior topo-1 ADC treatment.

Positive

• FDA granted two Fast Track designations for Emi-Le, potentially accelerating approval process
• Initial clinical data showed confirmed objective responses across all enrolled tumor types
• Demonstrated efficacy in TNBC patients previously treated with topo-1 ADC, indicating potential for second-line treatment

Negative

• Still in early Phase 1 clinical trials, indicating long path to potential commercialization
• Multiple competitors in the ADC space for breast cancer treatment

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

FAQ

What are the key findings from Mersana's (MRSN) Emi-Le Phase 1 trial as of December 2024?

The initial data showed Emi-Le was generally well tolerated with a differentiated safety profile and confirmed objective responses across all enrolled tumor types, including TNBC patients previously treated with topo-1 ADC.

What Fast Track designations has the FDA granted to Mersana's (MRSN) Emi-Le?

The FDA granted two Fast Track designations: 1) for advanced/metastatic TNBC and 2) for advanced/metastatic breast cancer in HER2 low/negative patients who received prior topo-1 ADC treatment.

When and where will Mersana (MRSN) present the Emi-Le clinical data at ASCO 2025?

The oral presentation will be on June 2, 2025, from 8:00-9:30 a.m. CT at McCormick Place, Chicago, with additional poster presentation from 9:00-12:00 p.m. CT the same day.

What types of cancers is Mersana's (MRSN) Emi-Le being investigated for?

Emi-Le is being investigated for solid tumors, including breast, endometrial and ovarian cancers, as well as adenoid cystic carcinoma type 1.