Pembrolizumab Monotherapy Versus Pembrolizumab Plus Chemotherapy in Patients With Head and Neck Squamous Cell Carcinoma

Background/Aim: Pembrolizumab monotherapy and pembrolizumab with chemotherapy (combination therapy) are standard treatments for recurrent and metastatic head and neck squamous cell carcinoma (R/M-HNSCC). This study aimed to explore which of the two, pembrolizumab monotherapy or combination therapy is superior for long-term use. Patients and Methods: Participants of the study were 139 patients with histologically confirmed squamous cell carcinoma who had been treated with pembrolizumab monotherapy or combination therapy at the Kyushu University and related facilities. We analysed differences regarding long-term survival rate and adverse events (AEs) between the pembrolizumab monotherapy and combination therapy groups. Results: The overall 2-year progression-free survival and 2-year overall survival were 28.6% and 41.8%, respectively; these results were not significantly different between the two groups. Patients in the monotherapy group with AEs had a significantly better prognosis than those without AEs (in both the monotherapy and combination therapy groups). In the combination therapy group, there was no difference in prognosis between those with AEs and those without AEs (p=0.636). Conclusion: Considering the treatment of R/M-HNSCC from a long-term perspective, we identified that it is better to use pembrolizumab as monotherapy than to use it in combination with chemotherapy. Combination therapy did not improve prognosis; moreover, it can also cause additional adverse effects.