Neoadjuvant Trial with Toripalimab, Albumin Paclitaxel, and Cisplatin on Pathological Response in Locally Advanced Resectable Oral Squamous Cell Carcinoma (illuminate Trial).

e18067 Background: In patients with locally advanced resectable oral squamous cell carcinoma (OSCC), major pathological response (MPR) to neoadjuvant therapy may translate into improved survival. The combination of anti-PD-1 and chemotherapy as neoadjuvant protocol has not been well reported in OSCC. Methods: The prospective single arm trial (NCT04473716) was performed to evaluate the neoadjuvant therapy with anti-PD-1 (Toripalimab) and chemotherapy (albumin paclitaxel/cisplatin) in OSCC patients at clinical stage III and IVA (AJCC 2018). The patients received two cycles (21 days each) of intravenous albumin paclitaxel (260mg/m2), cisplatin (75mg/m2) and Toripalimab (240mg) on day 1 and day 22. Radical surgery was performed within two weeks after neoadjuvant therapy. Post-operative radiotherapy/chemoradiotherapy was performed within 1.5 months after surgery. The primary endpoints were MPR and safety. Primary tumors were assessed for the percentage of residual viable tumor cells on HE staining, and tumor with no more than 10% viable tumor cell was considered as MPR. Results: From Nov. 2020 to Apr. 2021, 20 patients were enrolled, including 16 males and 4 females, at clinical stage III (16) and IVA (4). They aged from 19 to 75 (median 54) years . The primary tumor site was eight tongue, six mouth floor, three gingiva, two retromolar trigone and one buccal mucosa. The neoadjuvant therapy was well-tolerated with low incidence of grade 3-4 adverse events (AEs) including 5% grade 4 neutropenia, 10% grade 3 leukopenia, 5% grade 3 neutropenia, hypokalemia, vomiting, and rash each. Common grade 1-2 AEs included baldness/rash/itch/pain/fatigue, AST/ALT/uric acid elevation, nausea/vomiting/diarrhea, hyperbilirubinemia, proteinuria, neutropenia/leukopenia. All AEs were relieved after expectant treatment, the subsequent standard treatment was not delayed. According to pathological evaluation, the MPR rate was 60% (12/20), including 30% (6/20) pCR. According to RECIST 1.1, radiological evaluation on neoadjuvant therapy showed two CR, ten PR, seven SD and one PD. It was significantly consistent between pathological and radiological evaluation in linear regression analysis ( P＜0.0001). Combined positive score (CPS) of PD-L1 expression in biopsy was evaluated in 19 patients, MPR was archived in all 4 patients with CPS≥10, in 6 out of 8 patients (75%) with CPS≥1, and in 5 out of 11 patients (45.5%) with CPS < 1. Conclusions: Neoadjuvant therapy with combination of Toripalimab, albumin paclitaxel, and cisplatin in resectable OSCC patients is safe and well-tolerated, with high MPR rate. Clinical trial information: NCT04473716.