AACR 2019—Pembrolizumab offers new option for pretreated SCLC


  • Keren Landman, MD
  • Univadis
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Takeaway 

  • Pembrolizumab offers demonstrated promising antitumor activity with durable responses in patients with pretreated small-cell lung cancer (SCLC), according to a pooled analysis of the KEYNOTE-028 and KEYNOTE-158 trials.

Why this matters

  • Treatment options available to patients with advanced SCLC have historically been of limited survival benefit, with median duration of response (DOR) less than 2 months.
  • Of responders in this analysis (objective response rate [ORR], 19%), 61% had an estimated DOR of ≥18 months.

Study design

  • Exploratory pooled analysis of 83 patients from the SCLC cohorts of KEYNOTE-028 and KEYNOTE-158 trials, phase 1b/2 trials, respectively, of pembrolizumab in patients with PD-L1+ tumors (KEYNOTE-028) and tumors having any PD-L1 expression (KEYNOTE-158).
  • All patients had received ≥2 prior lines of therapy.
  • Funding: MSD Corp.

Key results

  • ORR was 19% (95% CI, 11%-29%) and included 2 complete responses and 14 partial responses.
  • Median PFS was 2.0 (95% CI, 1.9-3.4) months and OS was 7.7 (95% CI, 5.2-10.1) months after median 7.7 months follow-up.
    • 12-month PFS and OS: 17% and 34%, respectively.
    • 24-month PFS and OS: 13% and 21%, respectively.
  • Of 16 responders to therapy, 9 (61%) patients had an estimated DOR ≥18 months.
  • No new safety signals identified, although 6 patients had grade 3 adverse events (AEs). 
    • 2 patients had grade 5 AEs, 5 had AEs leading to discontinuation of study drug, and 20 had immune-related AEs or infusion reactions. 

Limitations

  • Retrospective, exploratory, pooled analysis of 2 single-arm studies.

Expert comment

  • In multiply relapsed SCLC, "responses are rare, long-term survival is unheard of, and the duration of response can be measured almost in minutes as opposed to in months. These findings are really stunning...and the impact on median overall survival is unprecedented in this disease," said Dr. Louis Wiener, co-chair of the AACR Annual Meeting Clinical Trials Committee and director of the Georgetown Lombardi Comprehensive Cancer Center. 

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