Abstract CT115: Updated survival results of the KEYNOTE-040 study of pembrolizumab vs standard-of-care chemotherapy for recurrent or metastatic head and neck squamous cell carcinoma

Background: It was known that survival data were outstanding on several patients (pts) when the final analysis of the multinational, open-label, phase 3 KEYNOTE-040 study (NCT02252042) of pembro vs SOC for recurrent or metastatic head and neck squamous cell carcinoma (R/M HNSCC) was performed. This abstract presents OS and PFS data using the same data cutoff date but with full survival acquisition. Methods: 495 pts with SCC of the oral cavity, oropharynx, hypopharynx, or larynx who had recurrence or PD after a platinum-containing regimen were randomized 1:1 to pembro 200 mg Q3W for 24 mo or investigator's choice of methotrexate, docetaxel, or cetuximab. Primary end point was OS in the ITT population. Key secondary end points included OS in the PD-L1 combined positive score (CPS) ≥1 population and PFS in the ITT and CPS ≥1 populations. OS and PFS in the PD-L1 tumor proportion score (TPS) ≥50% population were prespecified exploratory end points. Response was assessed per RECIST v1.1 by blinded, independent central review. Results: With full acquisition of survival data, HR was 0.80 (95% CI, 0.65-0.98) (nominal P = 0.0161) for OS and 0.96 (95% CI, 0.79-1.16) (nominal P = 0.33) for PFS in the ITT population. Median (95% CI) OS was 8.4 mo (6.4-9.4) for pembro vs 6.9 mo (5.9-8.0) for SOC; median PFS was 2.1 mo (2.1-2.3) vs 2.3 mo (2.1-2.8). Pembro benefit was greater in pts with PD-L1 CPS ≥1 and TPS ≥50% (Table). Conclusions: Pembro provided a clinically meaningful prolongation of OS compared with SOC in pts with R/M HNSCC. With full acquisition of survival data and compared with the previous analysis, the HR for OS decreased from 0.81 to 0.80, and the P value decreased from 0.0204 to 0.0161. There continued to be an enhanced benefit for pembro in pts with PD-L1–expressing tumors. Along with previously presented safety data, these results provide stronger support for the benefit of pembro in pts with R/M HNSCC. Table. OS and PFS in the PD-L1 CPS ≥1 and TPS ≥50% Populations CPS ≥1TPS ≥50%Pembron = 196SOCn = 191Pembro n = 64SOCn = 65OSMedian (95% CI), mo8.7 (6.9-11.4)7.1 (5.7-8.3)11.6(8.3-19.5)6.6(4.8-9.2)HR (95% CI)0.74 (0.58-0.93)0.53 (0.35-0.81)Pa0.00490.0014PFSMedian (95% CI), mo2.2 (2.1-3.0)2.3 (2.1-3.0)3.5(2.1-6.3)2.1(2.0-2.4)HR (95% CI)0.86 (0.69-1.06)0.58 (0.39-0.86)Pa0.080.003aNominal one-sided P value stratified by the randomization stratification factors. Citation Format: Denis Soulieres, Ezra Cohen, Christophe Le Tourneau, Jose Dinis, Lisa Licitra, Myung-Ju Ahn, Ainara Soria, Jean-Pascal Machiels, Nicolas Mach, Ranee Mehra, Barbara Burtness, Pingye Zhang, Jonathan Cheng, Ramona Swaby, Kevin J. Harrington. Updated survival results of the KEYNOTE-040 study of pembrolizumab vs standard-of-care chemotherapy for recurrent or metastatic head and neck squamous cell carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr CT115.