Real-world time on treatment analysis of pembrolizumab treated recurrent/metastatic head & neck squamous cell carcinoma (R/M HNSCC) patients stratified by ECOG PS in the United States.

Abstract

e18007 Background: There is limited evidence on the real-world use of pembrolizumab therapy post-approval in 1L R/M HNSCC. The study estimated real-world time on treatment (rwToT) of pembrolizumab monotherapy and pembrolizumab + platinum + 5FU for 1L R/M HNSCC patients, stratified by ECOG PS. Methods: This retrospective study of the nationwide de-identified electronic health record (EHR)-derived Flatiron Health Advanced H&N database selected patients initiating pembrolizumab monotherapy or pembrolizumab + platinum + 5FU between 07/01/19 - 12/31/20 with follow-up until 07/31/21. Patients with prior platinum-based therapy ≤6 months, prior primary cancers, or treatment with a clinical study drug were excluded. rwToT was defined as length of time between first and last documented administration date pembrolizumab. Patients with a record of next line of therapy, death, or treatment gap ≥120 days from the last administration date were considered discontinued. Patients without a discontinuation event were censored at the end of follow up. Kaplan-Meier analysis was conducted to assess median rwToT and landmark on-treatment rates. All results were stratified by ECOG PS 0-1 (similar to KEYNOTE-048, the registrational clinical trial) and ECOG PS 2-3. Results: A total of 402 patients initiated 1L treatment with pembrolizumab therapy. Of those patients, 297 (73.9%) had a recorded ECOG PS score, majority with an ECOG PS score of 0/1 (Overall: 77.8%, pembrolizumab monotherapy: 70.5%, pembrolizumab + platinum + 5-FU: 84.1%). The median rwToT was higher among the ECOG 0/1 patients compared to ECOG 2/3 patients for both regimens (pembrolizumab monotherapy: 4.4 vs 2.2 months, pembrolizumab + platinum + 5-FU: 5.0 vs 3.5 months). Conclusions: In the real-world, treatment duration with pembrolizumab monotherapy or pembrolizumab+platinum+5-FU in 1L R/M HNSCC was similar to KEYNOTE-048, when restricted to a trial-matched population of ECOG PS 0-1 patients. Treatment duration tended to be shorter in the real-world ECOG PS 2/3 population, who are commonly excluded from clinical trials.[Table: see text]