Palbociclib and cetuximab compared with placebo and cetuximab in platinum-resistant, cetuximab-naïve, human papillomavirus-unrelated recurrent or metastatic head and neck squamous cell carcinoma: A double-blind, randomized, phase 2 trial

Objectives: This study examined whether palbociclib and cetuximab prolonged overall survival (OS) versus placebo and cetuximab. Materials and methods: In this double-blind, randomized, phase 2 trial (PALATINUS), patients with platinum-resistant, cetuximab-naïve, human papillomavirus-unrelated recurrent/metastatic head and neck squamous-cell carcinoma received cetuximab and either palbociclib (arm A) or placebo (arm B). The primary endpoint was OS; 120 patients were required to have ≥80% power to detect a hazard ratio (HR) of 0.6 (median OS of 10 months in arm A and 6 months in arm B) using a one-sided, log-rank test (P = 0.10). Results: 125 patients were randomized (arm A: 65, arm B: 60). Median follow-up was 15.9 months (IQR, 11.3–22.7). Median OS was 9.7 months in arm A and 7.8 months in arm B (HR, 0.82; 95% CI, 0.54–1.25; P = 0.18). Median progression-free survival was 3.9 months in arm A and 4.6 months in arm B (HR, 1.00; 95% CI, 0.67–1.5; P = 0.50). The most common treatment-related adverse events in arm A were rash (39 patients, 60.9%) and neutropenia (26, 40.6%; three febrile) and in arm B was rash (32, 53.3%). Conclusion: There was no significant difference in median OS with palbociclib and cetuximab versus placebo and cetuximab. Funding: Pfizer Inc (NCT02499120).