Anti-PD-L1 durvalumab combined with cetuximab and radiotherapy in locally advanced squamous cell carcinoma of the head and neck: A phase II study.

TPS6094 Background: Head and neck squamous cell carcinoma (HNSCC) is characterized by prominent immune escape mechanisms. Potentially, the blockade of immune check points such as the PD-1/PD-L1 axis may stimulate the host T-cell activation against tumor cells and favor the FcγRIIIa-mediated, Cetuximab (CTX) induced antibody dependent cellular cytoxicity (ADCC). Durvalumab (DUR) is a humanized monoclonal IgG1, anti-PD-L1 antibody with promising activity in recurrent/metastatic HNSCC (NCT01693562). The aim of our study is to test the hypothesis that a restored ability of the host immune system via blockade of the PD1/PD-L1 axis through DUR may enhance the antitumor activity of both CTX and radiotherapy (RT) in locally advanced HNSCC, a setting with unmet needs for effective treatment options. Methods: In this open-label, multi-center, single-arm, phase II study, enrolled patients will receive RT (69.9 Gy/2.12 Gy fx in 33 fractions over 7 weeks) with concurrent CTX (400 mg/m2 1 week before RT start followed by 250 mg/m2 q1w) and DUR (1500 mg q4w starting from RT-CTX week 1) followed by adjuvant DUR (to a maximum of 6 months after completion of RT-CTX). Primary endpoint of the study is 2-year progression-free survival (PFS). Assuming a 2-year PFS of 66% based on historical data from RTOG study 0129, the experimental regimen is hypothesized to yield a 12% absolute increase at 2 years, corresponding to a hazard ratio of 0.6 (α = 0.1, power is 0.80 when the 2-year PFS is 78%). The required sample size with this design is 69 patients. A safety run-in is planned after the enrollment of first 12, 24 and 36 patients. Patients affected by high-risk ( > N2a or > T3, any N) larynx, hypopharynx and HPV negative oropharynx or HPV-positive oropharynx ( > N2b, > 10 pack/years) will be eligible. To avoid potential RT-induced chronic loco-regional immunosuppression, protocol-indications will be undertaken to restrict target volumes to sites of gross disease and subclinical high risk lymph node basins excluding areas deemed at very low risk of disease spread. For this purpose, dose-painting intensity modulated radiotherapy (IMRT) is mandatory for this study. Clinical trial information: 2016-004668-20.