A retrospective study of pembrolizumab plus chemotherapy for head and neck cancer patients: influence of response in combination phase on subsequent maintenance phase.

Abstract

Background: Pembrolizumab plus chemotherapy is considered one of the standard treatment regimens for patients with recurrent or metastatic head and neck squamous cell carcinoma (R/M HNSCC). The regimen comprises up to 6 cycles of pembrolizumab-chemotherapy combination phase and subsequent pembrolizumab maintenance phase. Pembrolizumab-chemotherapy combination confers high response rate, creating favorable conditions for pembrolizumab maintenance phase. This study examined the influence of response in the combination phase on the efficacy in subsequent maintenance phase.

Methods: We retrospectively reviewed the medical records of patients with R/M HNSCC who received pembrolizumab plus chemotherapy as a first-line regimen at Tohoku University Hospital, Sendai, Japan. Progression-free survival (PFS) was analyzed when it was divided into the combination and maintenance phases.

Results: A total of 44 patients were enrolled. The best overall response was observed in the combination phase in all patients, and the overall response rate was 46.3%. The median PFS was 5.8 months (95% CI: 4.9-7.1). PFS differed significantly according to the response. When analyzed separately, the PFS only in the maintenance phase differed depending on the response of partial response (PR) or stable disease (SD). There was no difference in the number of chemotherapy cycles between patients with PR and SD. Univariate and multivariate analyses showed that the response in the combination phase was significantly associated with PFS in the maintenance phase.

Conclusion: In the pembrolizumab plus chemotherapy regimen for patients with R/M HNSCC, the response in the combination phase may be associated with PFS in the maintenance phase.