Updated Survival Analysis of KEYNOTE-024: Pembrolizumab vs Platinum-Based Chemotherapy in Previously Untreated, Advanced NSCLC


Key Points

  • Updated findings indicate continued overall survival benefit of pembrolizumab vs chemotherapy.
  • The significant survival benefit was consistent across analyses, adjusting for patient crossover from chemotherapy to pembrolizumab.   

As reported in the Journal of Clinical Oncology by Reck et al, an updated analysis of the phase III KEYNOTE-024 trial indicates continued overall survival benefit of first-line pembrolizumab vs platinum-based chemotherapy in patients with advanced non–small cell lung cancer (NSCLC) with a programmed cell death ligand 1 (PD-L1) tumor proportion score ≥ 50% and no EGFR/ALK aberrations. The primary analysis of the study indicated significant benefits of pembrolizumab in progression-free survival—the primary endpoint—as well as overall survival.

Analysis Details

In the open-label trial, 305 patients were randomly assigned to pembrolizumab at 200 mg every 3 weeks for up to 2 years (n = 154) or investigator’s choice of platinum-based chemotherapy for 4 to 6 cycles (n = 151). The trial was stopped early on the basis of the data and safety monitoring committee recommendation to allow for the use of pembrolizumab in patients randomly assigned to chemotherapy.

As part of the study protocol, patients treated with chemotherapy were permitted to cross over to pembrolizumab on study. The current analysis examined the effects of on-study crossover using 3 methods: simplified two-stage method, rank-preserving structural failure time, and inverse probability of censoring weighting.

Updated Survival Analysis

At data cutoff in July 2017 for the current analysis, median follow-up was 25.2 months.

Median overall survival was 30.0 months in the pembrolizumab group vs 14.2 months in the chemotherapy group (hazard ratio [HR] = 0.63, 95% confidence interval [CI] = 0.47–0.86). During the study, 82 patients being treated with chemotherapy crossed over to treatment with pembrolizumab. When adjusted for crossover using the two-stage method, the adjusted hazard ratio for overall survival for pembrolizumab vs chemotherapy was 0.49 (95% CI = 0.34–0.69). Similar results were observed on analysis adjusting for crossover using rank-preserving structural failure time (adjusted HR = 0.52, 95% CI = 0.33–0.75) and inverse probability of censoring weighting (adjusted HR = 0.52, 95% CI = 0.33–0.80).

The investigators concluded, “With prolonged follow-up, first-line pembrolizumab monotherapy continues to demonstrate an [overall survival] benefit over chemotherapy in patients with previously untreated, advanced NSCLC without EGFR/ALK aberrations, despite crossover from the control arm to pembrolizumab as subsequent therapy.”

Martin Reck, MD, PhD, of LungenClinic Grosshansdorf, is the corresponding author for the Journal of Clinical Oncology article.

Disclosure: The study was supported by Merck Sharp & Dohme, a subsidiary of Merck & Co, Inc. The study authors’ full disclosures can be found at

The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.