Merck's immunotherapy drug, KEYTRUDA (pembrolizumab), has gained FDA approval for a new treatment approach for adult patients with resectable locally advanced head and neck squamous cell carcinoma (HNSCC), specifically those whose tumors show a certain level of PD-L1 expression . This innovative regimen involves using KEYTRUDA as a neoadjuvant treatment (given before surgery to shrink the tumor), continued as an adjuvant treatment (given after surgery in combination with standard radiation therapy, with or without cisplatin), and then as a single agent. This approval is based on the significant results from the Phase 3 KEYNOTE-689 trial, which demonstrated that this multi-stage KEYTRUDA regimen reduced the risk of event-free survival (EFS) events (such as disease recurrence, progression, or death) by 30% compared to standard care alone. While offering a promising new treatment paradigm, it's crucial to note that KEYTRUDA can cause immune-mediated adverse reactions, which can be severe or even fatal, as the drug works by modulating the body's immune system.