Merck Unveils Promising Phase 3 Results, Vibostolimab and Pembrolizumab Team Up Against Small Cell Lung Cancer

Merck, operating as MSD in markets outside the U.S. and Canada, has announced the termination of its Phase 3 KeyVibe-008 clinical trial. This decision follows a recommendation from an independent Data Monitoring Committee (DMC) after a pre-planned analysis revealed that the trial did not meet its primary endpoint for overall survival (OS), as it reached the pre-specified futility criteria.

The KeyVibe-008 trial was investigating a fixed-dose combination of vibostolimab, an anti-TIGIT antibody, and pembrolizumab (KEYTRUDA®), Merck’s renowned anti-PD-1 therapy, against atezolizumab combined with chemotherapy for the first-line treatment of patients with extensive-stage small cell lung cancer (ES-SCLC). Concerns were further raised as patients receiving the investigational combination experienced a higher incidence of adverse events (AEs), including immune-related AEs, compared to those in the control group.

In light of this development, Merck is in the process of informing study investigators and advising patients to discontinue treatment with the fixed-dose combination. Patients will be provided with the option to transition to treatment with atezolizumab. A thorough analysis of the study data is currently underway, and Merck plans to share the findings with the scientific community.

Dr. Marjorie Green, senior vice president and head of oncology, global clinical development, Merck Research Laboratories, “Small cell lung cancer remains a difficult disease to treat, as evident by the seven percent five-year survival rate and limited advancements in treatment options. Innovative research plays a critical role in improving our understanding to help patients achieve better outcomes, and while we hoped the results would be different, we remain committed to investigating novel approaches to treat this debilitating disease. We are extremely grateful to all of the patients, caregivers and investigators for their participation in this study.”

Merck is intensifying its commitment to lung cancer treatment through a comprehensive clinical development program that focuses on innovative therapies and earlier stages of the disease. The company is advancing several registration-enabling studies aimed at providing new options for patients.

In a significant collaboration with Daiichi Sankyo, Merck has announced the dosing of the first patient in the IDeate-Lung02 Phase 3 trial. This study is set to evaluate the safety and efficacy of ifinatamab deruxtecan (I-DXd) in patients with relapsed small cell lung cancer (SCLC) compared to the physician's choice of chemotherapy.

Furthermore, Merck and Daiichi Sankyo have broadened their global co-development and co-commercialization agreement to include Merck's investigational therapy MK-6070. This delta-like ligand 3 (DLL3) targeting T-cell engager is currently being studied in a Phase 1/2 clinical trial (NCT04471727). The partnership aims to explore potential combinations of MK-6070 with I-DXd in specific SCLC patient populations.

Merck is also continuing its investigations into the fixed-dose combination of vibostolimab and pembrolizumab in lung cancer. Ongoing Phase 3 studies—KeyVibe-003, KeyVibe-006, and KeyVibe-007—are regularly reviewed by external data monitoring committees, which have not recommended any modifications so far. Comprehensive safety monitoring continues for these studies as they progress.