Merus N.V. and Mersana Therapeutics are making strides in cancer treatment with their respective investigational therapies, petosemtamab and Emi-Le. Recent data and regulatory advancements highlight the potential of these drugs in addressing unmet needs in head and neck cancer and breast cancer.
Petosemtamab Shows Clinically Meaningful Activity in HNSCC
Merus N.V. (Nasdaq: MRUS) presented interim clinical data for petosemtamab in treating recurrent/metastatic head and neck squamous cell carcinoma (HNSCC). The data, presented at the European Society for Medical Oncology (ESMO®) Asia Congress, demonstrated clinically meaningful activity in previously treated patients.
In the 1500 mg Q2W cohort (75 evaluable patients):
- 36% confirmed overall response rate, including 4 complete responses
- Median duration of response of 6.2 months
- Overall survival of 11.4 months
In the 1100 mg Q2W cohort (27 evaluable patients):
- 19% overall response rate, including 2 complete responses
The drug showed a manageable safety profile with infusion-related reactions primarily occurring on day 1 of cycle 1. Clinical trials are ongoing, including phase 3 studies in HNSCC and expanded evaluation in metastatic colorectal cancer, with additional data updates planned for 2025.
Fabian Zohren, M.D., Ph.D., Chief Medical Officer of Merus, stated, "Petosemtamab clinical data in r/m HNSCC continues to demonstrate potentially practice changing efficacy and safety, both as monotherapy in 2L+ and in combination with pembrolizumab in 1L PD-L1 expressing HNSCC."
Emi-Le Receives Fast Track Designation for HER2-Negative Breast Cancer
Mersana Therapeutics, Inc. (NASDAQ: MRSN) announced positive initial Phase 1 clinical data for Emi-Le, the company's lead Dolasynthen ADC candidate targeting B7-H4, from 130 patients who were enrolled in dose escalation and backfill cohorts as of a December 13, 2024 data cutoff. The company also announced that Emi-Le had received a second Fast Track designation from the U.S. Food and Drug Administration (FDA) for HER2-negative breast cancer patients who have previously been treated with at least one topo-1 ADC.
The expansion portion of the company's Phase 1 clinical trial continues at a dose of 67.4 mg/m² administered every four weeks in patients with TNBC who had received one to four prior lines of therapy, including at least one topo-1 ADC. In parallel, the company continues to explore higher doses in dose escalation and backfill cohorts to identify a second dose for expansion.
Martin Huber, M.D., President and Chief Executive Officer of Mersana Therapeutics, said, "We made significant progress advancing the clinical development of Emi-Le in 2024. With promising monotherapy activity reported in patients across multiple tumors, including those with heavily pretreated triple-negative breast cancer, as well as a differentiated tolerability profile that may enable combination approaches, we believe Emi-Le offers us unique development opportunities that are unavailable to other B7-H4 ADCs."
