Merck announced first-time data from the Phase 3 KEYNOTE-598 study evaluating KEYTRUDA, Merck’s anti-PD-1 therapy, in combination with ipilimumab (Yervoy®) compared with KEYTRUDA monotherapy as first-line treatment for patients with metastatic non-small cell lung cancer (NSCLC) without EGFR or ALK genomic tumor aberrations and whose tumors express PD-L1 (tumor proportion score [TPS] =50%). Results of the study showed that the addition of ipilimumab to KEYTRUDA did not improve overall survival (OS) or progression-free survival (PFS) but added toxicity compared with KEYTRUDA monotherapy in these patients. The median OS was 21.4 months for patients randomized to KEYTRUDA in combination with ipilimumab versus 21.9 months for those randomized to KEYTRUDA monotherapy (HR=1.08 [95% CI, 0.85-1.37]; p=0.74). Additionally, the median PFS was 8.2 months for patients in the combination arm versus 8.4 months for those in the KEYTRUDA monotherapy arm (HR=1.06 [95% CI, 0.86-1.30]; p=0.72). These results were presented in the Presidential Symposium at the IASLC 2020 World Conference on Lung Cancer hosted by the International Association for the Study of Lung Cancer on Jan. 29 and published in theJournal of Clinical Oncology. As previously announced in Nov. 2020, the study was discontinued due to futility based on the recommendation of an independent Data Monitoring Committee (DMC), which determined the benefit/risk profile of KEYTRUDA in combination with ipilimumab did not support continuing the trial. The DMC also advised that patients in the study discontinue treatment with ipilimumab/placebo. KEYNOTE-598 (ClinicalTrials.gov [1], NCT03302234 [2]) is a randomized, double-blind, Phase 3 trial designed to evaluate KEYTRUDA in combination with ipilimumab compared to KEYTRUDA monotherapy as first-line treatment for patients with metastatic NSCLC without EGFR or ALK genomic tumor aberrations and whose tumors express PD-L1 (TPS =50%). The dual primary endpoints are OS and PFS. Secondary endpoints include objective response rate (ORR), duration of response (DOR) and safety. The study enrolled 568 patients who were randomized 1:1 to receive KEYTRUDA (200 mg intravenously [IV] on Day 1 of each three-week cycle for up to 35 cycles) in combination with ipilimumab (1 mg/kg IV on Day 1 of each six-week cycle for up to 18 cycles); or KEYTRUDA (200 mg IV on Day 1 of each three-week cycle for up to 35 cycles) as monotherapy. Non-binding futility criteria for the study were based on restricted mean survival time (RMST), an alternative outcome measure estimated as the area under the survival curve through a fixed timepoint. The pre-specified criteria were differences in RMST for KEYTRUDA in combination with ipilimumab and KEYTRUDA monotherapy of =0.2 at the maximum observation time and =0.1 at 24 months of follow-up. As of data cut-off, the median study follow-up was 20.6 months. Findings showed the median OS was 21.4 months for patients randomized to KEYTRUDA in combination with ipilimumab (n=284) versus 21.9 months for those randomized to KEYTRUDA monotherapy (n=284) (HR=1.08 [95% CI, 0.85-1.37]; p=0.74). The differences in RMST for KEYTRUDA in combination with ipilimumab and KEYTRUDA monotherapy were -0.56 at the maximum observation time and -0.52 at 24 months, meeting the futility criteria for the trial and confirming the benefit/risk profile of the combination did not support continuing the study. Additionally, the median PFS was 8.2 months for patients randomized to KEYTRUDA in combination with ipilimumab versus 8.4 months for those randomized to KEYTRUDA monotherapy (HR=1.06 [95% CI, 0.86-1.30]; p=0.72). In both arms of the study, ORR was 45.4%; the median DOR was 16.1 months for patients randomized to KEYTRUDA in combination with ipilimumab versus 17.3 months for those randomized to KEYTRUDA monotherapy.