Core Insights - Merus N.V. (MRUS) shares have increased by 29.9% over the past three months, driven by positive interim results from a phase II study of its bispecific antibody, petosemtamab (MCLA-158), in combination with Merck's Keytruda for treating PD-L1-positive recurrent or metastatic head and neck squamous cell carcinoma (HNSCC) [1][4] Study Results - As of February 27, 2025, 45 patients were treated, with 43 deemed efficacy-evaluable, resulting in a confirmed overall response rate (ORR) of 63%, which included six complete responses and 21 partial responses [2] - The ORR varied with PD-L1 expression levels, showing a 73% ORR in patients with a combined positive score (CPS) greater than 20 and 47% in those with CPS 1–19 [2] - Median progression-free survival was reported at nine months, with an overall survival rate of 79% at 12 months [3] Safety Profile - The safety profile of the combination therapy was manageable, with no significant overlapping toxicities reported with Keytruda; treatment-related adverse events occurred in all patients, with infusion-related reactions observed in 38% [5][6] Future Prospects - The promising data suggests that the petosemtamab combination therapy could become a new standard of care for HNSCC, a cancer type with poor prognosis [6] - Merus is also conducting a registrational phase III study (LiGeR-HN1) for the combination therapy and another study (LiGeR-HN2) for petosemtamab monotherapy [7][8] Market Context - Merck's Keytruda, a leading anti-PD-1 therapy, generated $7.21 billion in sales in Q1 2025, reflecting a 6% year-over-year increase, and continues to expand into new indications and markets [8][10]

Core Insights - Merus N.V. announced interim clinical data for petosemtamab in combination with pembrolizumab, showing a 63% response rate among evaluable patients and a 79% overall survival rate at 12 months [1][2][3] Clinical Data Summary - The ongoing phase 2 trial included 45 patients, with 43 evaluable for efficacy, showing a confirmed overall response rate of 63% (27/43) [3] - The median progression-free survival was reported at 9 months, with a median follow-up of 14.3 months [3] - Among the evaluable patients, 6 achieved complete responses and 21 had partial responses, with responses observed across different PD-L1 levels [3] - The combination treatment was generally well tolerated, with 60% of patients experiencing grade ≥3 treatment-emergent adverse events [3] Future Outlook - The company anticipates sharing top-line interim readouts from one or both phase 3 trials in 2026, indicating a strong belief in the potential of petosemtamab to become a new standard of care for head and neck cancer [2][3]

UTRECHT, The Netherlands and CAMBRIDGE, Mass., May 15, 2025 (GLOBE NEWSWIRE) -- Merus N.V. (Nasdaq: MRUS) ("Merus", "the Company", "we", or "our"), an oncology company developing innovative, full-length multispecific antibodies and antibody drug conjugates (Biclonics, Triclonics and ADClonics), today announced publication on the mechanism of action of petosemtamab, a bispecific antibody targeting Epidermal Growth Factor Receptor (EGFR) and Leucine-Rich G (LGR5), in the scientific journal "Cancers", a MDPI p ...

- Petosemtamab in combination with pembrolizumab in 1L PD-L1+ r/m HNSCC phase 2 trial ongoing with clinical data update at 2025 ASCO® Annual Meeting - Based on the Company’s current operating plan, existing cash, cash equivalents and marketable securities expected to fund Merus’ operations into 2028 UTRECHT, The Netherlands and CAMBRIDGE, Mass., May 07, 2025 (GLOBE NEWSWIRE) -- Merus N.V. (Nasdaq: MRUS) (Merus, the Company, we, or our), an oncology company developing innovative, full-length multispecific an ...