Safety and Efficacy of Cetuximab-Based Salvage Chemotherapy After Checkpoint Inhibitors in Head and Neck Cancer.

BACKGROUND: There are still few data on the activity and safety of cetuximab-based salvage chemotherapy after immunotherapy (SCAI) in patients with squamous cell cancer of the head and neck (SCCHN).
MATERIALS AND METHODS: This was a retrospective study of patients with SCCHN who received cetuximab-based SCAI after programmed cell death protein 1 or programmed cell death ligand 1(PD[L]1) inhibitors. Overall response rate (ORR) and disease control rate (DCR) with SCAI and with last chemotherapy before immunotherapy (LCBI) by RECIST 1.1, percentage change from baseline in target lesions (PCTL), progression-free survival (PFS), overall survival (OS), treatment compliance, and toxicity were evaluated.
RESULTS: Between March 2016 and November 2019, 23 patients were identified. SCAI consisted of cetuximab-based combinations (3-weekly cisplatin-5FU-cetuximab [n = 2], weekly paclitaxel-cetuximab [n = 17], weekly cisplatin-cetuximab [n = 2], weekly carboplatin-paclitaxel-cetuximab [n = 2]). ORR was 56.5% (11 partial response, 2 complete response). DCR was 78.3%. Among 13 objective responders, median best PCTL was -53.5% (range, -30% to -100%). Median OS and PFS were 12 months and 6 months, respectively. In 10 patients receiving LCBI, ORR to LCBI was 40%, whereas ORR to SCAI achieved 60%. In LCBI-treated patients, median PFS with LCBI was 8 months and median PFS and OS with SCAI were 7 months and 12 months, respectively. Reduced dose intensity of the chemotherapy and cetuximab components occurred in 82.6% and 52.2% of the patients. Grade 1 or 2 adverse events (AEs) occurred in all patients. Grade 3 or 4 AEs developed in 65%, being grade 3 in all of them except in one patient (grade 4 neutropenia). There were no treatment-related deaths.
CONCLUSION: Cetuximab-based salvage chemotherapy after PD(L)1 inhibitors associated with high response rates and deep tumor reductions with a manageable safety profile. Subsequent lines of therapy may explain the long survival achieved in our series. These results invite to design studies to elucidate the best therapeutic sequence in patients with SCCHN in the immunotherapy era. IMPLICATIONS FOR PRACTICE: Cetuximab-based salvage chemotherapy (SCAI) achieved high response rates in patients with recurrent/metastatic squamous cell cancer of the head and neck (SCCHN) after progression to PD-1/PD-L1 inhibitors. Objective response rate was higher than and progression-free survival was comparable to that of chemotherapy administered before immunotherapy (IO). In most patients, SCAI consisted of weekly, well-tolerated regimens. These observations have implications for current practice because of the limited evidence to date in SCCHN and the scant therapeutic options in this disease and invite to elucidate which may be the best treatment sequence for patients with head and neck cancer in the IO era.