Objective response rate predicts survival in recurrent or metastatic head and neck squamous cell carcinoma treated with immune checkpoint blockade but not with targeted therapy: A retrospective multicenter study.

[BACKGROUND] It remains unknown whether the treatment response to immune checkpoint inhibitors (ICIs) or cetuximab-based chemotherapy (the EXTREME regimen) reflects the survival of patients with recurrent or metastatic head and neck squamous cell carcinoma (R/M HNSCC). A retrospective multicenter study was conducted to elucidate the relationship between objective treatment response and survival in patients with R/M HNSCC.

[METHODS] Thirteen university hospitals and cancer centers participated in this study. The clinical course of patients with R/M HNSCC treated with ICIs or the EXTREME regimen as first-line treatment was retrospectively investigated. The outcomes of interest were progression-free survival (PFS) and overall survival (OS). In addition to objective responses, adverse events were evaluated for each treatment.

[RESULTS] In total, 751 patients with R/M HNSCC were included in this retrospective study. The best response to first-line treatment was significantly associated with improved prognosis only in ICI-based therapy, not in cetuximab-based targeted therapy. ICI responders had longer PFS and OS than EXTREME responders. The median PFS was 22.9 months and the median OS was not reached in ICI responders, whereas the median PFS and OS in EXTREME responders were 5.0 and 16.9 months, respectively. In contrast, EXTREME nonresponders had longer OS than ICI nonresponders. The median OS was 11.9 and 13.0 months in ICI and EXTREME nonresponders, respectively. Immune-related adverse events were also associated with prognosis in patients treated with ICIs.

[CONCLUSIONS] This study highlights the prognostic significance of achieving an objective response with first-line ICI-based, not cetuximab-based, treatment in R/M HNSCC.