Trial results for the Phase 3 study NCT05224141, investigating atezolizumab in combination with chemotherapy for first-line treatment of Extensive-Stage Small Cell Lung Cancer (ES-SCLC), were posted on ClinicalTrials.gov on 2025-05-30. The study compared atezolizumab with a pembrolizumab/vibostolimab co-formulation, with atezolizumab demonstrating a numerically longer median overall survival of 12.9 months compared to 11.5 months for the comparator.
Background
The study, titled 'Pembrolizumab/Vibostolimab (MK-7684A) or Atezolizumab in Combination With Chemotherapy in First Line Treatment of Extensive-Stage Small Cell Lung Cancer (MK-7684A-008/KEYVIBE-008)', aimed to evaluate the combination of pembrolizumab/vibostolimab with etoposide/platinum chemotherapy compared to atezolizumab with etoposide/platinum chemotherapy in the first-line treatment of ES-SCLC.
Trial design
The KEYVIBE-008 study (NCT05224141) was a Phase 3 trial that enrolled 460 participants with Extensive-Stage Small Cell Lung Cancer. The study evaluated two treatment arms: one receiving a fixed dose pembrolizumab/vibostolimab co-formulation (MK-7684A) combined with etoposide/platinum chemotherapy, followed by MK-7684A; and the other receiving atezolizumab combined with etoposide/platinum chemotherapy, followed by atezolizumab. The primary hypothesis was to assess the superiority of MK-7684A over atezolizumab with respect to overall survival.
Key results
The trial results provided key measurements for several outcomes:
- Overall Survival (OS): The median OS for the pembrolizumab/vibostolimab group was 11.5 months, compared to 12.9 months for the atezolizumab group. A statistical analysis yielded a Hazard Ratio (HR) of 1.26 (95.0% Confidence Interval: 1.0 to 1.59) with a p-value of 0.9762.
- Progression-Free Survival (PFS): The median PFS was 5.3 months for the pembrolizumab/vibostolimab group and 4.5 months for the atezolizumab group. The Hazard Ratio (HR) was 1.01 (95.0% Confidence Interval: 0.82 to 1.23) with a p-value of 0.5316.
- Objective Response Rate (ORR): The ORR was 71.7 Percentage of Participants for the pembrolizumab/vibostolimab group and 74.8 Percentage of Participants for the atezolizumab group. The percent difference was -3.1 (95.0% Confidence Interval: -11.1 to 4.9).
- Duration of Response (DOR): The median DOR was 4.2 months for the pembrolizumab/vibostolimab group and 3.9 months for the atezolizumab group.
Statistical analyses were stratified by ECOG performance status (0 vs. 1), LDH (≤ULN vs. >ULN), liver metastasis (Yes or No), and brain metastasis (Yes or No).
What this means
The results of the KEYVIBE-008 trial indicate that the primary hypothesis of superiority for pembrolizumab/vibostolimab over atezolizumab in terms of overall survival was not met. While atezolizumab showed a numerically longer median overall survival of 12.9 months compared to 11.5 months for pembrolizumab/vibostolimab, the statistical analysis for OS yielded a high p-value of 0.9762, suggesting no statistically significant difference between the two regimens for this outcome. Similarly, for progression-free survival, objective response rate, and duration of response, the observed numerical differences between the two treatment arms did not demonstrate statistical significance, with p-values of 0.5316 for PFS and a 95% CI for ORR percent difference spanning zero. These findings suggest that neither regimen demonstrated a statistically significant advantage over the other in this first-line treatment setting for ES-SCLC.
Source
The information regarding these trial results was obtained from ClinicalTrials.gov, a public database of clinical studies. The results for study NCT05224141, titled 'Pembrolizumab/Vibostolimab (MK-7684A) or Atezolizumab in Combination With Chemotherapy in First Line Treatment of Extensive-Stage Small Cell Lung Cancer (MK-7684A-008/KEYVIBE-008)', were posted on 2025-05-30 on clinicaltrials.gov.