Phase II Study of Pembrolizumab As First-Line, Single-Drug Therapy for Patients With Unresectable Cutaneous Squamous Cell Carcinomas

J Clin Oncol. 2020 Sep 10;38(26):3051-3061. doi: 10.1200/JCO.19.03357. Epub 2020 Jul 30.


Purpose: To evaluate first-line pembrolizumab monotherapy efficacy and safety in patients with unresectable cutaneous squamous cell carcinomas (CSCCs).

Patients and methods: Patients, predominantly men, with their CSSCs' immunohistochemically determined programmed cell death-ligand 1 (PD-L1) status determined (tumor proportion score threshold, 1%), received pembrolizumab (200 mg every 3 weeks). The primary endpoint was the 39-patient primary cohort's objective response rate at week 15 (ORRW15). Secondary objectives were best ORR, overall survival (OS), progression-free survival (PFS), duration of response (DOR), safety, ORR according to PD-L1 status and health-related quality of life using Functional Assessment of Cancer Therapy-General (FACT-G) score. An 18-patient expansion cohort, recruited to power the study to evaluate the ORRW15 difference between PD-L1+ and PD-L1- patients, was assessed for ORR, disease control rate, and safety, but not survival.

Results: Median age of all patients was 79 years. The primary cohort's ORRW15 was 41% (95% CI, 26% to 58%), including 13 partial and 3 complete responses. Best responses were 8 partial and 8 complete responses. At a median follow-up of 22.4 months, respective median PFS, DOR, and OS were 6.7 months, not reached, and 25.3 months, respectively. Pembrolizumab-related adverse events affected 71% of the patients, and 4 (7%) were grade ≥ 3. One death was related to rapid CSCC progression; another resulted from a fatal second aggressive head and neck squamous cell carcinoma diagnosed 15 weeks postinclusion. ORRW15 for the entire population was 42%; it was significantly higher for PD-L1+ patients (55%) versus PD-L1- patients (17%; P = .02). Responders' W15 total FACT-G score had improved (P = .025) compared with nonresponders.

Conclusion: First-line pembrolizumab monotherapy exhibited promising anti-CSCC activity, with durable responses and manageable safety. PD-L1 positivity appears to be predictive of pembrolizumab efficacy.

Trial registration: NCT02883556.

Publication types

  • Clinical Trial, Phase II
  • Multicenter Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Antibodies, Monoclonal, Humanized / adverse effects
  • Antibodies, Monoclonal, Humanized / therapeutic use*
  • Antineoplastic Agents, Immunological / adverse effects
  • Antineoplastic Agents, Immunological / therapeutic use*
  • B7-H1 Antigen / antagonists & inhibitors*
  • B7-H1 Antigen / immunology
  • Carcinoma, Squamous Cell / drug therapy*
  • Carcinoma, Squamous Cell / immunology
  • Carcinoma, Squamous Cell / mortality
  • Carcinoma, Squamous Cell / pathology
  • Disease Progression
  • Female
  • France
  • Humans
  • Immune Checkpoint Inhibitors / adverse effects
  • Immune Checkpoint Inhibitors / therapeutic use*
  • Male
  • Middle Aged
  • Progression-Free Survival
  • Quality of Life
  • Skin Neoplasms / drug therapy*
  • Skin Neoplasms / immunology
  • Skin Neoplasms / mortality
  • Skin Neoplasms / pathology
  • Time Factors


  • Antibodies, Monoclonal, Humanized
  • Antineoplastic Agents, Immunological
  • B7-H1 Antigen
  • CD274 protein, human
  • Immune Checkpoint Inhibitors
  • pembrolizumab

Associated data