Merck announces positive results from phase 2 trial evaluating coformulation of vibostolimab, pembrolizumab in lung cancer patients

Data presented at ESMO I-O showed that vibostolimab/pembrolizumab plus docetaxel extended median progression-free survival (PFS) by 2.4 months compared to those treated with docetaxel alone, though the results did not reach statistical significance (5.6 months vs. 3.2 months; HR=0.77 [95% CI, 0.53-1.13]; p=0.0910). Vibostolimab/pembrolizumab alone did not show an improvement in median PFS compared to docetaxel alone (2.7 months vs. 3.2 months; HR=1.40 [95% CI, 0.96-2.02]; p=0.9622).

“This study was designed to evaluate a coformulation of vibostolimab and pembrolizumab in a population of patients who are heavily pre-treated and have progressed following treatment with standard of care therapies, often leaving them with limited treatment options and a poor prognosis,” said Dr. Scot Ebbinghaus, vice president, global clinical development, Merck Research Laboratories. “We will leverage our evolving understanding of novel combinations and coformulations to help inform our comprehensive research program evaluating this coformulation across a wide range of tumor types.”

Data from key secondary endpoints, including overall survival (OS), overall response rate (ORR) and duration of response (DOR) were also presented. Vibostolimab/pembrolizumab plus docetaxel improved OS compared with docetaxel alone, though these results did not reach statistical significance (HR=0.76 [95% CI, 0.50-1.15]). Vibostolimab/pembrolizumab alone did not show an improvement in OS compared to docetaxel alone (HR=1.05 [95% CI, 0.70-1.58). The median OS for vibostolimab/pembrolizumab plus docetaxel was 10.2 months (95% CI, 8.6-14.9), 7.5 months (95% CI, 5.2-13.4) for vibostolimab/pembrolizumab alone and 8.8 months (95% CI, 6.4-11.1) for docetaxel. The ORR for patients receiving vibostolimab/pembrolizumab plus docetaxel was 29.9% (95% CI, 20.5-40.6), 6.0% (95% CI, 2.0-13.5) for vibostolimab/pembrolizumab alone and 15.3% (95% CI, 8.4-24.7) for docetaxel. Median DOR was 6.5 months (range, 2.1+ to 15.4+ months) for the vibostolimab/pembrolizumab plus docetaxel arm. Median DOR was not reached for the vibostolimab/pembrolizumab arm (range, 2.6+ to 6.2+ months) and for the docetaxel arm (range, 1.6 to 11.1+ months).

The safety profile of vibostolimab/pembrolizumab was consistent with that observed for vibostolimab and pembrolizumab in previously reported studies, with no new safety signals observed. Immune-mediated adverse events and infusion reactions occurred in 29.4% of patients who received vibostolimab/pembrolizumab plus docetaxel, 20.5% of those who received vibostolimab/pembrolizumab alone and 12% of those who received docetaxel alone. There were four treatment-related deaths in the vibostolimab/pembrolizumab plus docetaxel arm of the study, and one in each of the vibostolimab/pembrolizumab and docetaxel only arms. In the vibostolimab/pembrolizumab only arm of the study, there was a lower incidence of treatment-related adverse events (TRAEs) of any grade compared to the docetaxel only arm (60.2% vs. 89.2%), and 96.5% of patients in the vibostolimab/pembrolizumab plus docetaxel arm had TRAEs. 

Vibostolimab is Merck’s investigational anti-TIGIT antibody that restores antitumor activity by blocking the TIGIT receptor from binding to its ligands (CD112 and CD155), thereby activating T lymphocytes that help destroy tumor cells. Merck has an extensive clinical development program evaluating the safety and efficacy of the vibostolimab/pembrolizumab coformulation alone and in combination with other agents in over 4,000 patients. Ongoing Phase 3 studies in lung cancer include KeyVibe-003, KeyVibe-006, KeyVibe-007 and KeyVibe-008, as well as KeyVibe-010 in melanoma.