• In the Phase Ib KEYNOTE-028 study of pembrolizumab in patients with PD-L1-positive relapsed small cell lung cancer, promising antitumor activity was observed, and the safety profile was consistent with previous experiences with this agent in other tumor types.
• The Phase I/II CheckMate 032 trial demonstrated durable responses with nivolumab monotherapy and nivolumab/ipilimumab in patients with progressive small cell lung cancer after at least 1 prior therapy.

At ASCO we saw 2 important and encouraging papers on checkpoint inhibitors in extensive-stage small cell lung cancer. The first evaluated pembrolizumab in patients with at least 1% PD-L1 staining (approximately one quarter of those screened) and demonstrated a 35% response rate with a predictable safety profile. An ongoing Phase II trial is evaluating this agent as maintenance treatment after chemotherapy, and another Phase I study combines pembrolizumab with chemoradiation therapy.

The second study reported at ASCO, a Phase I/II trial evaluating nivolumab alone or with ipilimumab in patients with recurrent small cell lung cancer after at least 1 prior therapy, demonstrated responses with both treatment approaches. In this cancer with a substantial incidence and mortality rate that has generally not been associated with targetable mutations, these findings are among the most encouraging we have seen in a long time.