KEYNOTE-689: Phase 3 study of adjuvant and neoadjuvant pembrolizumab combined with standard of care (SOC) in patients with resectable, locally advanced head and neck squamous cell carcinoma.

TPS6090 Background: Evidence of efficacy and pathological response at the time of surgery was reported in two phase 2 studies (NCT02296684 and NCT02641093) of preoperative pembrolizumab in patients with high-risk, resectable, locally advanced (LA) head and neck squamous cell carcinoma (HNSCC). The randomized, open-label, phase 3 KEYNOTE-689 trial ( NCT03765918) will evaluate efficacy and safety of pembrolizumab as neoadjuvant and adjuvant therapy in combination with SOC (radiotherapy ± cisplatin) in patients with previously untreated, resectable LA HNSCC. Methods: Patients with newly diagnosed LA HNSCC will be randomly assigned 1:1 to two treatment arms. Patients in arm A will receive neoadjuvant pembrolizumab (200 mg Q3W for two cycles) followed by surgical resection then SOC plus adjuvant pembrolizumab (15 cycles). Patients in arm B will undergo only surgical resection followed by adjuvant SOC. Eligibility criteria will include age ≥18 years; newly diagnosed, resectable, stage III/IVA HNSCC (AJCC Cancer Staging Manual, 8th edition); and ECOG performance status 0-1. Randomization will be stratified by primary tumor site (oropharynx/oral cavity vs larynx vs hypopharynx), tumor stage (III vs IVA), and HPV p16 status (oropharynx p16 positive vs oropharynx p16 negative or larynx/hypopharynx/oral cavity). Treatment will continue until disease progression, unacceptable toxicity, or decision to withdraw. Patients in arm A will undergo the first radiologic imaging assessment after two cycles of neoadjuvant pembrolizumab and before surgery. In both arms, postoperative imaging will be performed 12 weeks after SOC, then every 3 months until the end of year 3, and then every 6 months until the end of year 5. Dual primary end points are major pathological response, defined as ≤10% invasive squamous cell carcinoma within resected primary tumor and sampled regional lymph nodes per blinded central pathology, and event-free survival. Secondary end points include overall survival, pathological complete response, and safety and tolerability. Recruitment is ongoing and will continue until ~600 patients are enrolled. Clinical trial information: NCT03765918.