Induction chemoimmunotherapy followed by radiotherapy in locally advanced head and neck squamous cell carcinoma: A real-world study.

131 Background: Patients with locally advanced head and neck squamous cell cancers (LAHNSCC) present poor prognosis despite multi-disciplinary comprehensive treatment, and novel treatment strategies are urgently needed. Recently, several phase II clinical trials reported encouraging pathological complete response rate of induction chemoimmunotherapy (IC+ICI) in LAHNSCC, suggesting potentially long-term survival benefits. Therefore, we conducted this real-world study to compare the efficacy of IC+ICI followed by radiotherapy (RT) versus induction chemotherapy (IC) followed by RT in LAHNSCC. Methods: We retrospectively included patients with LAHNSCC from Sun Yat-sen University Cancer center database treated with IC+ICI followed by RT or IC followed by RT between 1/2018-12/2021. Survival outcomes and adverse effects (AEs) were compared between the two groups. Results: A total of 262 patients were included: 128 (48.9%) in the IC+ICI group, and 134 (51.1%) in the IC group. Median age for the whole cohort was 60 (53–66) years, and the male-to-female ratio is 8.9:1. Most patients (84.4%) had stage IV disease. The median follow-up time was 26.7 (IQR 25.8-29.6) months. Marginally significant higher objective response rate (ORR) was observed in the IC+ICI group than that in the IC group (81.25% vs 72.39%, P=0.09). Patients in the IC+ICI group had significantly better results than those in the IC group in 2-year overall survival (OS; 88.9% vs. 71.5%, P<0.001), disease-free survival (DFS; 77.5% vs. 58.3%, P=0.005), locoregional relapse-free survival (LRRFS; 78.4% vs. 59.7%, P=0.009) and distant metastasis-free survival (DMFS; 87.5% vs. 64.6%, P<0.001). Multivariate analysis confirmed that combining immunotherapy in the induction stage was an independent prognostic factor for OS (HR 0.40, 95%CI 0.19-0.84), DFS (HR 0.45, 95%CI 0.28-0.72), LRRFS (HR 0.56, 95%CI 0.31-0.99), and DMFS (HR 0.37, 95%CI 0.19-0.73). The incidences of G3/4 AEs between the IC+ICI group and the IC group were comparable during the induction stage (6.25% vs 12.69%, P = 0.076) as well as the radiotherapy stage (14.06% vs 14.18%, P = 0.978). Conclusions: This study firstly reported that IC+ICI followed by RT was superior to IC followed by RT in long-term survival outcome in LAHNSCC.