Merck discontinues clinical development of two investigational antibodies

USA—Merck has discontinued its clinical development programs for two investigational antibodies: vibostolimab, an anti-TIGIT antibody, and favezelimab, an anti-LAG-3 antibody.

This comes a few months after the company announced that it is discontinuing a pivotal Phase 3 trial evaluating a treatment for extensive-stage small cell lung cancer.

Both drugs had been undergoing trials in combination with pembrolizumab (KEYTRUDA®), a widely used cancer treatment.

Vibostolimab was being tested in the KeyVibe program, which evaluated its combination with pembrolizumab in patients with non-small cell lung cancer (NSCLC).

This included Phase 3 trials KeyVibe-003 and KeyVibe-007, where the fixed-dose combination of vibostolimab and pembrolizumab showed disappointing results.

According to an independent Data Monitoring Committee (DMC), both trials met pre-specified futility criteria, meaning they were unlikely to meet the goal of improving overall survival.

As a result, Merck decided to discontinue these trials, as well as the KeyVibe-006 trial and other studies related to vibostolimab.

However, the safety profile of the combination was consistent with previous findings, with no new safety concerns.

The combination of both drugs led to more immune-related adverse events than pembrolizumab alone, which is typical in dual checkpoint inhibitor therapies.

In a related decision, Merck has also halted the clinical development of favezelimab, another investigational antibody.

The Phase 3 KEYFORM-008 trial, which was testing the combination of favezelimab and pembrolizumab in patients with relapsed or refractory classical Hodgkin lymphoma (cHL), will no longer enroll new patients.

While patients currently enrolled in the trial will be allowed to continue treatment until the study ends, Merck has decided to discontinue further development of favezelimab after careful analysis of the data.

 This decision comes as the company focuses its resources on other promising oncology treatments in its pipeline. Significantly, no safety concerns were raised about the favezelimab-pembrolizumab combination.

Merck emphasized that this decision reflects its commitment to prioritizing the most promising therapies in its extensive oncology pipeline.

The company continues to evaluate the data from the trials and plans to share the results with the scientific community.

Dr. Marjorie Green, Senior Vice President and Head of Oncology at Merck Research Laboratories, commented that the decision to end development of vibostolimab and favezelimab was made after thorough analysis of the trial data.

She expressed gratitude to the patients, caregivers, and investigators who contributed to the trials and reaffirmed Merck’s commitment to advancing cancer treatments with the greatest potential to improve patient outcomes.

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