Merus Reports Promising Results for Bispecific Antibody in Head and Neck Cancer

Merus, a biopharmaceutical company specializing in innovative antibody therapeutics, has announced encouraging data from its phase 2 trial of petosemtamab, a bispecific antibody targeting EGFR and LGR5, in combination with Merck's Keytruda for the treatment of recurrent or metastatic head and neck squamous cell carcinoma (HNSCC).

Impressive Survival and Response Rates

The phase 2 trial, which evaluated 45 patients with PD-L1-positive HNSCC, demonstrated a 79% 12-month survival rate, a figure that Merus CEO Bill Lundberg described as "unprecedented" in the context of head and neck cancer literature. The study also reported a 63% overall response rate among 43 evaluable patients, including six complete responses.

Median progression-free survival was nine months, with the study yet to reach the median duration of response and overall survival at the data cutoff. These results compare favorably to historical data for Keytruda monotherapy, which showed a 19% response rate and 51% 12-month survival in a registrational trial.

Potential for Accelerated Approval

Merus executives expressed optimism about the possibility of seeking accelerated approval for petosemtamab based on these early results. CEO Lundberg stated, "We do believe that there's a real opportunity ... for there to be a potential accelerated approval based on an early endpoint such as ORR with confirmation coming from survival in the same setting."

The company is currently conducting two phase 3 registration trials, which are expected to be "substantially enrolled" by the end of the year. This terminology, which aligns with FDA criteria for accelerated approval, has fueled speculation about a potential filing before the pivotal trial readout in 2026.

Market Response and Future Outlook

The announcement of these promising results led to a significant market response, with Merus shares jumping 13% in premarket trading, rising above $47 on a $2.8 billion market cap. William Blair analysts have reinforced their belief that petosemtamab has a "best-in-disease profile."

As Merus continues to advance its clinical program for petosemtamab, the biopharmaceutical industry will be closely watching the development of this potentially transformative treatment for head and neck cancer patients.