6MO Pembrolizumab Plus Ipilimumab or Placebo in Previously Untreated Metastatic NSCLC with PD-L1 Tumor Proportion Score ≥50%: KEYNOTE-598 3-Year Follow-Up

At protocol-specified interim analysis 1 (IA1; data cutoff Sep 1, 2020) of the phase 3 KEYNOTE-598 study (NCT03302234), adding ipilimumab (ipi) to pembrolizumab (pembro) did not improve OS (HR, 1.08) or PFS (HR, 1.06) vs placebo (pbo) + pembro in patients (pts) with previously untreated stage IV NSCLC with PD-L1 tumor proportion score (TPS) ≥50%. Per external DMC recommendation at IA1, ipi and pbo were discontinued and pembro monotherapy continued in both arms. We report 13 additional mo follow-up from IA1 and outcomes of pts who completed 35 cycles of pembro and pts who started second-course pembro.