ASCO 2020 – Adding pembrolizumab boosts PFS in extensive-stage SCLC


  • Kelli Whitlock Burton
  • Oncology Conference reports
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Takeaway

  • Adding pembrolizumab to chemotherapy with etoposide and platinum (EP) offered significantly better PFS than placebo+EP as firstline treatment for extensive-stage small-cell lung cancer (ES-SCLC).

Why this matters

  • The standard treatment for ES-SCLC is chemotherapy with EP, even though response rates with the therapy are not durable and median OS is approximately 10 months.

Study design

  • International, randomized, double-blind, placebo-controlled, phase 3 KEYNOTE-604 study.
  • 453 patients with untreated ES-SCLC received pembrolizumab with EP (n=228) or placebo+EP (n=225).
  • Funding: Merck & Co., Inc., Kenilworth, NJ, USA.

Key results

  • Median PFS:
    • 4.5 months with pembrolizumab+EP vs
    • 4.3 months with placebo+EP. 
  • 12-month PFS estimates:
    • 13.6% with pembrolizumab+EP vs 
    • 3.1% with placebo+EP.
  • PFS was significantly better with pembrolizumab+EP (HR, 0.75; P=.0023).
  • Median OS was not significantly different between groups (HR, 0.80; P=.0164).
  • Objective response rate:
    • 70.6% (95% CI, 64.2%-76.4%) with pembrolizumab+EP vs
    • 61.8% (95% CI, 55.1-68.2) with placebo+EP.
  • Median duration of response:
    • 4.2 months with pembrolizumab vs
    • 3.7 months with placebo.
  • At 1 year, the estimated proportion of ongoing responses was 19.3% with pembrolizumab vs 3.3% with placebo.
  • Rate of adverse events was similar between groups.

Limitations

  • Highly selected clinical trial population.
  • Results presented at a conference without peer review.