Merus N.V. (NASDAQ: MRUS) Q1 2025 Earnings Call | 05/23/2025

Key Highlights

• ASCO 2025 Presentation: The call discussed data to be presented at the ASCO 2025 Annual Meeting on June 2, 2025, highlighting positive results from the Phase 2 trial.
• Company Overview: Merus is an oncology-focused company with a proprietary BiClonix and Triclonix antibody platform. They recently received FDA approval for Bizangri.
• Petosemtamab: This is a BiClonix antibody targeting EGFR and LGR5. It acts through three mechanisms: EGFR inhibition, LGR5-mediated EGFR degradation, and ADCC-enhanced immune response.

Prior Clinical Data Recap

• ASMO Asia: Petosemtamab monotherapy (1500mg every two weeks) in 75 efficacy-evaluated patients with second-line plus R/M HNSCC showed a confirmed overall response rate (ORR) of 36%, median duration of response (DOR) of 6.2 months, median progression-free survival (PFS) of 4.9 months, and median overall survival (OS) of 11.4 months. The monotherapy safety profile was favorable.
• ASCO 2024: Early data on petosemtamab + pembrolizumab in first-line setting (24 patients) showed an ORR of 67% (including one complete response). The combination was well-tolerated.

ASCO 2025 Data Update: Petosemtamab + Pembrolizumab in First-Line R/M HNSCC (PD-L1 Positive)

• Study Design: Patients had PD-L1 positive, treatment-naive R/M HNSCC. Petosemtamab (1500mg biweekly) + pembrolizumab (400mg every six weeks) was administered until progression/toxicity.
• Data Cutoff: February 27, 2025 (median follow-up: 14.3 months). 43 patients were evaluable for efficacy.
• Patient Characteristics: Median age 64, mostly male (78%), ECOG PS 0/1 (36%/64%), typical primary tumor locations, and all PD-L1 positive. 18% were P16-positive.
• Treatment Duration: Median exposure to petosemtamab was 8.3 months.
• Safety: The combination was well-tolerated with no significant overlapping toxicities. EGFR antibody-associated toxicities (skin, GI) were lower than with standard EGFR therapies. Infusion-related reactions (38% all grades, 7% Grade 3) were mainly during the first infusion and resolved. No related Grade 5 adverse events.
• Efficacy:
  • ORR: 63% (27/43 patients). The lower bound of the 95% confidence interval was 49%, significantly higher than historical pembrolizumab monotherapy (19%) and pembrolizumab + chemotherapy (37%).
  • Complete Response (CR): 6 patients achieved CR (including conversions from PR/SD).
  • Time to Response: Median 1.9 months.
  • DOR: Not reached (14 responders still on therapy).
  • PFS: Median 9 months (approximately three times longer than historical pembrolizumab monotherapy).
  • OS: Not reached. 12-month OS rate was 79%, dramatically higher than historical pembrolizumab monotherapy (51%).
• Key Conclusions:
  • Confirmed significant impact on ORR in a larger population.
  • Strong internal consistency across multiple efficacy endpoints.
  • Petosemtamab + pembrolizumab shows dramatically greater efficacy than pembrolizumab alone.
  • Favorable safety profile.

Ongoing Phase 3 Trials and Commercial Opportunity

• Trial Enrollment: Both Phase 3 trials have over 120 sites activated and are expected to be substantially enrolled by the end of 2025.
• Patent Estate: Strong patent protection for platform technology, petosemtamab composition of matter, methods of treatment, combination therapy, etc., potentially extending exclusivity beyond 2040.
• Market Opportunity: H&N cancer is a large and growing market. The first-line setting treats approximately 55,000 patients globally (17,000 in the US). Later-line settings treat approximately 22,000 globally per year. The current market is estimated at around $4 billion in 2024.
• Commercial Strategy: Petosemtamab is positioned as a potential first-in-class and best-in-class chemo-free standard of care in R/M HNSCC.