Real-World Patient Characteristics and Time on Treatment Outcomes Among Patients Receiving First-Line Pembrolizumab in the Treatment of Recurrent/Metastatic Head and Neck Squamous Cell Carcinoma (R/M HNSCC) in the United States

Abstract

<h3>Purpose/Objective(s)</h3> In July 2019, the FDA approved pembrolizumab in combination with platinum and fluorouracil (P+C), or as monotherapy [P, in combined positive score (CPS) ≥1 population], for the first-line (1L) treatment of patients with R/M HNSCC based on KEYNOTE-048 trial results. Limited evidence exists on the real-world use of pembrolizumab therapy post-approval. The objective of this study was to assess demographic and clinical characteristics, and treatment patterns among patients initiating pembrolizumab therapy in 1L R/M HNSCC. <h3>Materials/Methods</h3> A retrospective cohort study was conducted using the Flatiron Health Advanced Head and Neck database. The study cohort included adult R/M HNSCC patients, who initiated 1L P or P+C between 07/01/2019 - 12/31/2020. Patients were excluded if they received prior platinum treatment ≤6 months of 1L pembrolizumab therapy, had other primary cancers before R/M HNSCC diagnosis, or were treated with a clinical study drug. Real-world time on treatment (rwToT) was assessed using Kaplan-Meier methods. <h3>Results</h3> A total of 402 patients initiated 1L pembrolizumab therapy, [P (n=264), P+C (n=138)]. Descriptive analyses showed differences between patients receiving P versus P+C (Table 1). Patients receiving P were older, and more likely to have a history of smoking, being HPV positive, and have higher ECOG score at 1L initiation. Other patient characteristics were similar between P versus P+C. Treatment pattern results showed that 68.2% (P: 72.0%, P+C: 60.9%) of pembrolizumab treated patients had a record of PD-L1 test before or within 30 days of 1L initiation in the data. Majority of these PD-L1 tests assessed CPS scores (71.8%) with 82.2% of patients CPS≥1 (P 85.8%, P+C 73.2%). The median 1L rwToT was 3.9 months (IQR: 1.4-8.5) for P and 4.9 months (IQR: 1.6−10.4) for P+C, consistent with the results of the KEYNOTE-048 trial [P: 3.5 months (IQR: 1.4-7.6), P+C: 5.8 months (IQR: 2.8-9.7)]. <h3>Conclusion</h3> In our real-world study, some patient differences regarding patient characteristics were observed between patients initiating P vs. P+C. Furthermore, 1L use of pembrolizumab was observed in a severe R/M HNSCC population (ECOG ≥ 2). rwTOT with P and P+C were consistent with results of the KEYNOTE-048 trial, thus validating trial results. Table 1. Baseline characteristics of patients initiating 1L P versus P+C