Background: PD-1 (programmed cell death protein-1) inhibitors combination with chemotherapy has a significant efficacy and approved indications in the first-line treatment of head and neck squamous cell carcinoma (HNSCC), but the efficacy of these combination therapies in locally advanced hypopharyngeal squamous cell carcinoma (HPSCC) remains unexplored. We conducted a single-arm, phase II trial to assess the efficacy and safety of toripalimab (a novel PD-1 inhibitor) combined with chemotherapy as induction treatment in locally advanced HPSCC. Methods: Patients with locally advanced HPSCC (cT1N+M0 or T2-4NanyM0, AJCC 8.0) were eligible. All patients received 2 cycles of intravenous docetaxel (75mg/m²), cisplatin (75mg/m²) and toripalimab (240mg) on day 1 every 21 days, followed by radical surgery or concurrent chemoradiotherapy (CCRT) with cisplatin (100mg/m², q21d). The primary endpoint was objective response rate (ORR) assessed by investigators per RECIST v1.1. Secondary endpoints were major pathologic response (MPR), 2 year disease-free survival (DFS) rate in patients received surgery, 2 year progression-free survival (PFS) rate in patients received CCRT and 2 year overall survival (OS) rate in all patients. Results: From July 2020 to January 2023, 34 patients (median age: 59, range: 46-72, male: 100%, stag IV: 100%) were enrolled. Patients with stage IVA an IVB disease were 19 (19/34, 55.9%) and 15 (15/34, 44.1%), respectively. 33 patients completed 2 cycles induction treatment and efficacy evaluation (1 patient dropped out). The evaluated ORR was 54.5%, including 3 pts achieving complete response and 15 achieving partial response. PD-L1 status (combined positive score, CPS) were known in 8 patients, ORR were 80% (4/5) and 66.7% (4/6) in patients with CPS≥20 and CPS≥1, respectively, 2 patients with CPS＜1 had stable disease. Treatment-related grade 3-4 adverse events occurred in 45.5% (15/33) of patients, leukopenia (42.4%) and neutropenia (3.1%). Immune-related AEs were acceptable, 1 patient (1/33, 3.0%) experienced grade 2 interstitial pneumonia and 2 patients (2/33, 6.1%) experienced grade 1 rash. In the following treatment, 27 patients (27/33, 81.8%) performed CCRT. 4 patients (4/33, 12.1%) underwent surgery followed by CCRT and 2 patients (2/33, 6.1%) refused further treatment. Among these 17 patients finished CCRT and radiological assessment, 9 patients (9/17, 52.9%) had complete response, 7 patients (7/17, 41.2%) had partial response and 1 patient (1/17, 5.9%) had progressive disease. Survival data are not mature by cut-off date. Conclusions: Induction therapy of toripalimab combined with docetaxel and cisplatin was well tolerated and highly efficient for locally advanced HPSCC. Clinical trial information: NCT04296747.