A phase 1 study of pembrolizumab plus ipilimumab as first-line treatment in Japanese patients with advanced non-small-cell lung cancer.

Background: Part D of the open-label, phase 1 KEYNOTE-011 study (ClinicalTrials.gov, NCT01840579) evaluated the safety and tolerability, pharmacokinetics, and antitumor activity of pembrolizumab plus ipilimumab as first-line treatment in Japanese participants with advanced NSCLC.

Methods: Eligible participants were aged ≥20 years with previously untreated stage IIIB/IV NSCLC (any tumor PD-L1 status permitted). Participants received ≤35 doses of pembrolizumab 200 mg every 3 weeks intravenously (days 1 and 22 of 6-week cycles) plus ≤18 doses of ipilimumab 1 mg/kg every 6 weeks intravenously. The primary endpoint was dose-limiting toxicities (DLTs) occurring during the DLT evaluation period (first 6 weeks of study treatment). The secondary endpoint was pembrolizumab pharmacokinetics; exploratory endpoints included evaluation of antitumor activity. Results were summarized descriptively.

Results: All 6 participants enrolled in Part D received ≥1 dose of pembrolizumab plus ipilimumab. No DLTs were observed. AEs of any cause were reported in 5 participants (83%; grade 3-4, n = 2 [33%]). No fatal AEs occurred. Two participants had AEs leading to discontinuation: grade 3 pneumonia (n = 1; not treatment-related) and grade 2 organizing pneumonia (n = 1; treatment-related). The geometric mean (% coefficient of variation) pembrolizumab maximum and minimum serum concentrations were 72.7 μg/mL (10.1%) and 8.3 μg/mL (16.2%), respectively, at cycle 1 and 86.2 μg/mL (3.6%) and 28.1 μg/mL (23.6%), respectively, at cycle 4. Objective response rate was 50% (95% CI, 12%-88%); 3 participants had PR.

Conclusion: Pembrolizumab plus ipilimumab had a manageable safety profile and showed antitumor activity in Japanese participants with previously untreated advanced NSCLC.