An open-label, single-center phase II trial of cadonilimab (an anti-PD-1/CTLA-4 bispecific antibody) in combination with platinum-based dual-drug neoadjuvant chemotherapy for locally advanced, resectable head and neck squamous cell carcinoma.

6044 Background: Consensus on neoadjuvant treatment strategies for resectable head and neck squamous cell carcinoma (HNSCC) is not proposed currently. Preclinical and clinical findings suggested that PD-1/CTLA-4 bispecific antibodies may have synergistic anti-tumor activity. This study aimed to explore the safety and activity of cadonilimab in combination with platinum-based dual-drug neoadjuvant chemotherapy in locally advanced, resectable HNSCC. Methods: In this open-label phase II trial, eligible patients with untreated locally advanced, resectable HNSCC (T2N2-3M0、T3-4N0-3M0; stage III-IV, AJCC 8th Edition) were enrolled to receive cadonilimab (10 mg/kg) and platinum-based dual-drug docetaxel (75 mg/m2) plus cisplatin (60 mg/m2) on day 1 of each 21-day cycle for three cycles, followed by surgery and postoperative adjuvant therapy. The primary endpoint was objective response rate (ORR) per RECIST1.1. Secondary endpoints included pathologic complete response (pCR), safety, disease-free survival (DFS), and overall survival (OS). Results: Between July 2023 and December 2023, 24 patients were enrolled (median age, 55 years range 34–69; 21 men 87.5%), tumors were located in the oral cavity (10/24, 41.7%), hypopharynx (8/24, 33.3%) and larynx (6/24, 25.0%), 20 (83.3%) patients were clinical T3/4 while 10 patients (41.7%) ≥N2 . After completion of neoadjuvant therapy, the ORR was 87.5% (21/24). Of the 24 patients, 12 (50.0%) patients reached pCR. Treatment-related adverse events (TRAEs) occurred in 14 (58.3%) patients. Grade 3-4 TRAEs were reported in 4 (16.7%) patients, including rash (12.5%), pruritus (12.5%) and Guillain-Barre syndrome (4.2%). DFS and OS data were not yet mature as of the cutoff date (January 1,2024). Conclusions: Cadonilimab plus platinum-based dual-drug neoadjuvant chemotherapy achieved favorable ORR and pCR with manageable toxicities in patients with HNSCC. Follow-up is still underway to obtain long-term survival data. Clinical trial information: NCT06023875 .