Response to salvage chemotherapy after progression on immune checkpoint inhibitors in patients with recurrent and/or metastatic squamous cell carcinoma of the head and neck

Background: Immune checkpoint inhibitors (ICI) are active in patients with recurrent/metastatic squamous cell carcinoma of the head and neck (R/M SCCHN). Recent data suggest that exposure to ICI improves response to salvage chemotherapy (SCT) in advanced non–small-cell lung cancer. We evaluated response to chemotherapy in patients who had progressed on ICI in patients with R/M SCCHN. Patients and methods: A retrospective study was conducted at 4 French centres. Eligibility criteria were patients who progressed after treatment with ICI for R/M SCCHN and received SCT and for whom efficacy data were available between September 2014 and January 2018. Results: Of 232 patients treated with ICI, 82 met eligibility criteria: 84% were male. ICI was given as monotherapy in 45% of patients or as combination in 55%. SCT included taxanes (56.1%), cetuximab in combination with taxanes or platinum (50%), platinum-based regimen (36.6%). The median number of treatment lines before SCT was 2 (range 1–6). The objective response rate (ORR) to SCT was 30%. Three patients (4%) presented complete response and 22 patients (27%) had partial response. Median progression-free survival was 3.6 months and median overall survival was 7.8 months. The age at SCT, initial tumour location, number of prior chemotherapy regimens, type of chemotherapy before ICI, best response to ICI, site of relapse and Eastern Cooperative Oncology Group at SCT were not associated with response to SCT on univariate analysis. Conclusion: In R/M SCCHN, the ORR to SCT was high (30%) suggesting that exposure to ICI may increase tumour sensitivity to chemotherapy.