The neoadjuvant paradigm reinvigorated: a review of pre-surgical immunotherapy in HNSCC.

Background: There remains up to a 50% recurrence rate in advanced p16 neck squamous cell carcinoma with current standard of care treatment. In an attempt to improve survival, multiple trials administering induction or neoadjuvant chemotherapy have been conducted but none demonstrated improved overall survival. The established efficacy of immune checkpoint inhibitors in the recurrent and metastatic setting has produced widespread interest in their neoadjuvant use. Purpose: To survey the landscape of active neoadjuvant immunotherapy trials in head and neck squamous cell carcinoma and summarize and synthesize currently available outcomes from these trials. Conclusions: Neoadjuvant immunotherapy has proven safe and well tolerated in head and neck squamous cell carcinoma with encouraging efficacy results, including relatively high rates of pathologic response. Ongoing studies offer an opportunity to study immune responses in vivo. PD-L1 positivity, high tumor mutational burden and infiltration of NK cells, CD8, CD26 and Tim3 positive lymphocytes at time of surgery have been correlated with pathologic responses. We await updated reports of disease free survival and overall survival data and results of ongoing phase III studies utilizing neoadjuvant immunotherapy to determine if this treatment paradigm will have a place in the standard of care treatment in head and neck squamous cell carcinoma.