KEYNOTE-028 is a multicohort phase 1b trial of pembrolizumab in patients with PD-L1–positive advanced solid tumors. Pembrolizumab is administered at a dose of 10 mg/kg every 2 weeks for up to 2 years or until confirmed progression or intolerable toxicity, death, withdrawal of consent, or physician decision. The primary end point was objective response rate (ORR; investigator assessed), whereas secondary end points included safety, progression-free survival (PFS), and overall survival (OS).
A total of 24 patients with pretreated extensive-stage disease (ED) small-cell lung cancer (SCLC) and tumor PD-L1 positivity were enrolled in KEYNOTE-028 and received 1 or more doses of pembrolizumab. At the data cut-off date in mid-June 2016, median follow-up duration was 9.8 months (range, 0.5-24.0 months) with 3 patients remaining on treatment.
Among 24 evaluable patients, ORR was 33% (95% confidence interval [CI], 16%-55%), including 1 complete and 7 partial responses. Median duration of response was 19.4 months (range, 3.6-20+ months). Median PFS was 1.9 months (95% CI, 2-6 months). The 6- and 12-month PFS rates were 29% and 24%, respectively. Median OS was 9.7 months (95% CI, 4.1 months to not reached). The 6- and 12-month OS rates were 66% and 38%, respectively.
No new safety concerns were noted. Sixteen of 24 (67%) patients experienced treatment-related adverse events (AEs). Two patients experienced grade 3 to 5 treatment-related AEs: 1 patient had hyperbilirubinemia (grade 3) and 1 patient experienced grade 3 asthenia and grade 5 colitis.
Researchers concluded that pembrolizumab demonstrates promising antitumor activity in patients who relapsed with PD-L1–positive ED SCLC. Responses were durable for the subset of patients who achieved objective responses with pembrolizumab.
Ott PA, et al. WCLC 2016. Abstract OA 05.01. ID 6198.
