Merus Announces Publication of an Abstract on Petosemtamab with Pembrolizumab as 1L treatment of r/m HNSCC at the 2024 ASCO Annual Meeting

-   60% response rate observed among 10 evaluable patients

-   Favorable safety profile in 26 patients enrolled as of the abstract cutoff date, with no significant overlapping toxicities observed

-   Conference call on Tuesday, May 28 at 8:00 a.m. ET to discuss full ASCO data set

UTRECHT, The Netherlands and CAMBRIDGE, Mass., May 23, 2024 (GLOBE NEWSWIRE) -- Merus N.V. (Nasdaq: MRUS) (Merus, the Company, we, or our), a clinical-stage oncology company developing innovative, full-length multispecific antibodies (Biclonics and Triclonics), today announced the publication of an abstract regarding petosemtamab in combination with pembrolizumab on the 2024 American Society of Clinical Oncology (ASCO) Annual Meeting website. The abstract presents interim clinical data from a cohort of 26 patients enrolled as of the abstract cutoff date, evaluating the combination in first line (1L) recurrent/metastatic (r/m) head and neck squamous cell carcinoma (HNSCC) for presentation at the 2024 ASCO Annual Meeting taking place in Chicago, May 31-June 4, 2024.

The full dataset for these patients will be discussed on a conference call on Tuesday, May 28 at 8:00 a.m. ET.

“We believe petosemtamab continues to demonstrate potential best in class safety and efficacy in head and neck cancer. We are encouraged with the well tolerated safety profile of the combination of petosemtamab and pembrolizumab, particularly with a low rate of Grade 3 or greater adverse events, and a low rate of infusion-related reactions observed,” said Bill Lundberg, M.D., President, Chief Executive Officer of Merus. “These data in the abstract provide encouraging efficacy albeit from an early cutoff date, with less mature data. And we look forward to our conference call, Tuesday May 28, to discuss the more mature clinical update from a later cutoff date where the response rate further improved.”

Petosemtamab (MCLA-158: EGFR x LGR5 Biclonics): Solid Tumors

Rapid oral presentation title: Petosemtamab (MCLA-158) with pembrolizumab as first-line (1L) treatment of recurrent/metastatic (r/m) head and neck squamous cell carcinoma (HNSCC): Phase 2 study.
Observations in the abstract include:  

• As of a November 6, 2023 data cutoff date, 26 patients (pts) were treated; with 24 continuing therapy
  • 10 pts were evaluable for response (≥2 cycles and ≥1 post-baseline scan, or early progressive disease [PD]) and 6 responses were observed. This included 1 confirmed complete response, 2 confirmed partial responses, and 3 unconfirmed partial responses (2 confirmed as of the abstract submission and the 3^rd also subsequently confirmed) by Response Evaluation Criteria in Solid Tumors v1.1
  • The combination was well tolerated and no significant overlapping toxicities were observed. Treatment-emergent adverse events were reported in all patients, most were Grade 1 or 2 in severity. Infusion related reactions (composite term) were reported in 26.9% (all Grades) of which 3.8% were Grade 3, and all occurred during first infusion and resolved.