Can Adjuvant Atezolizumab Improve Outcomes in Locally Advanced Squamous Cell Carcinoma of the Head and Neck?

Immune checkpoint inhibitors (ICIs) have been shown to improve survival in patients with recurrent and/or metastatic squamous cell carcinoma of the head and neck (SCCHN), but their use in locally advanced SCCHN has been less successful. Two previous clinical trials evaluating the addition of ICIs to concurrent definitive chemoradiation failed to demonstrate improvements in progression-free or event-free survival (EFS; Lancet Oncol 2021; 22:450, Lancet Oncol 2024; 25:572). Now, investigators report results from a study of adjuvant ICI therapy.

In this multinational, phase 3 trial, 406 patients who had undergone multimodal definitive treatment for high-risk locally advanced SCCHN were randomized to receive either atezolizumab (1200 mg) or placebo every 3 weeks for up to 1 year. Approximately 62% of patients had received primary nonsurgical management (chemoradiation or induction chemotherapy followed by radiation or chemoradiation); the remainder had received surgery followed by radiation or chemoradiation, or induction chemotherapy followed by surgery with or without radiation.

At a median follow-up of 46.5 months, median EFS (the primary endpoint) was not significantly different between the atezolizumab and placebo groups (59.5 and 52.7 months); this finding was consistent across subgroups. Overall survival rates at 24 months were also similar (82.0% and 79.2%). Treatment-related adverse events were manageable and consistent with previously known profiles.