Merus (MRUS) Investor Update summary

Clinical Data and Efficacy Update

• Interim Phase II data for petosemtamab in second-line plus recurrent/metastatic HNSCC show a 36% overall response rate, median progression-free survival of 4.9–5.2 months, and median overall survival of 11.4–12.5 months, with four complete responses among 27 responders.

• Median duration of response was 6.2 months, with responses deepening over time and one complete response ongoing for over 3 years as of July 2024.

• Efficacy was observed in both HPV-positive and negative subgroups, including in HPV-positive disease where EGFR antibodies typically show no activity.

• The safety profile remains favorable, with manageable infusion-related reactions reduced by updated administration protocols and no new safety signals identified.

• The 1,500 mg biweekly dose is the recommended Phase III dose, with higher target engagement and manageable adverse events.

Commercial and Market Opportunity

• Petosemtamab is positioned as a potential new standard of care in second-line plus HNSCC, with a market opportunity exceeding $5 billion annually by 2028 in the G7 markets.

• The asset shows promise as both monotherapy and in combination with pembrolizumab, with a 67% response rate in PD-L1 positive disease in combination.

• Expansion into colorectal cancer is underway, targeting both first-line and third-line plus settings, with interim data expected in 2025.

• The technology platform and strong IP position support long-term exclusivity, with patents extending potentially beyond 2040.

• Cash position of $783M as of 3Q24, expected to fund operations into 2028.

Clinical Development and Regulatory Status

• Two Phase III registration trials in HNSCC are ongoing, with accelerated site activation and enrollment aiming for substantial completion by end of 2025.

• The FDA has granted Breakthrough Therapy Designation for petosemtamab in second-line and later HNSCC post-platinum and anti-PD-1/PD-L1 therapy.

• The company is planning a clinical data update for petosemtamab plus pembrolizumab in first-line PD-L1 positive HNSCC in 2025.

• Expansion into metastatic colorectal cancer includes ongoing and planned phase 2 trials in multiple lines, with initial data expected in 2025.

• The development strategy includes robust trial design, stratification for key prognostic factors, and benchmarks against KEYNOTE-048 and LEAP-010 trials.