Merck announced that the Phase 3 KEYNOTE-604 trial investigating KEYTRUDA, Merck’s anti-PD-1 therapy, in combination with chemotherapy met one of its dual primary endpoints of progression-free survival (PFS) in the first-line treatment of patients with extensive stage small cell lung cancer (ES-SCLC). In the study, treatment with KEYTRUDA in combination with chemotherapy (etoposide plus cisplatin or carboplatin) resulted in a statistically significant improvement in PFS compared to chemotherapy alone (HR=0.75 [95% CI, 0.61-0.91]), which was observed at a prior interim analysis. At the final analysis of the study, there was also an improvement in overall survival (OS) for patients treated with KEYTRUDA in combination with chemotherapy compared to chemotherapy alone; however, these OS results did not meet statistical significance per the pre-specified statistical plan (HR=0.80 [95% CI, 0.64-0.98]). The safety profile of KEYTRUDA in this trial was consistent with that observed in previously reported studies. Results will be presented at an upcoming medical meeting and discussed with regulatory authorities. In addition to KEYTRUDA’s five current indications in lung cancer, Merck is continuing to study KEYTRUDA across multiple settings and stages of lung cancer through a broad clinical program, which is comprised of more than 10,000 patients enrolled or expected to be enrolled across 20 Merck-sponsored clinical studies.