Clinical Data
In the overall SCLC patient cohort (n=107), data at ASCO showed an ORR of 18.7 percent (95% CI, 11.8-27.4), with a complete response rate of three percent and a partial response rate of 16 percent. Median DOR was not reached (range, 2.1+ to 18.7+ months) and 73 percent of patients had a DOR of 12 months or longer. Median PFS was 2.0 months (95% CI, 1.9-2.1) with six- and 12-month PFS rates of 23.7 percent and 16.8 percent, respectively. Median OS was 8.7 months (95% CI, 5.6-12.0) with six- and 12-month OS rates of 57.5 percent and 40.2 percent, respectively.In the pre-specified, exploratory analyses based on PD-L1 status, patients whose tumors expressed PD-L1 (n=42) showed an ORR of 35.7 percent (95% CI, 21.6–52.0), with a complete response rate of five percent and a partial response rate of 31 percent. Additionally, median PFS was 2.1 months (95% CI, 2.0-8.1) with six- and 12-month PFS rates of 38.9 percent and 28.5 percent, respectively. Median OS was 14.9 months (95% CI, 5.6-NR) with six- and 12-month OS rates of 66.0 percent and 53.1 percent, respectively.In patients whose tumors did not express PD-L1 (n=50), ORR was six percent (95% CI, 1.3-16.5), with a complete response rate of two percent and a partial response rate of four percent. Median PFS was 1.9 months (95% CI, 1.6-2.0) with six- and 12-month PFS rates of 14.3 percent and 8.2 percent, respectively. Median OS was 5.9 months (95% CI, 3.3-10.1) with six- and 12-month OS rates of 48.3 percent and 30.7 percent, respectively. In other pre-specified subgroup analyses, the ORR was generally consistent across clinically relevant subgroups, including patients (n=61) who had received two or more prior lines of therapy where the ORR was 23 percent (95% CI, 13.2-35.5).The safety profile was consistent with what has been seen in previously reported studies of KEYTRUDA monotherapy in lung cancer. Treatment-related adverse events (TRAEs) occurring in 10 percent or more of patients were fatigue (14%), pruritus (12%), hypothyroidism (12%), decreased appetite (10%) and nausea (10%). Thirteen patients had grade 3-4 TRAEs; two deaths occurred due to TRAEs (pneumonia and encephalopathy). Immune-mediated adverse events and infusion reactions were reported in some patients. Hypothyroidism was the most commonly reported immune-mediated adverse event, followed by hyperthyroidism and severe skin reactions.