Major pathological response to neoadjuvant immune-related therapy and influence on long-term survival in patients with locally advanced oral squamous cell carcinoma.

6042 Background: In neoadjuvant immune-related therapy (NAIT) for patients with locally advanced oral squamous cell carcinoma (LAOSCC), it has been highly anticipated whether major pathological response (MPR) can translate into long-term survival benefits. The aim of this study was to demonstrate the relationship between MPR to NAIT and long-term survival in LAOSCC. Methods: Two single-arm trials were included in this study on NAIT of neoadjuvant immunochemotherapy (NAICT) with Toripalimab plus albumin paclitaxel/cisplatin (NCT04473716) or neoadjuvant immunotarget therapy (NAITT) with Camrelizumab plus Apatinib (NCT04393506) in LAOSCC patients at clinical stage III and IVA (AJCC 2018). The patients received two cycles (21 days each) of NAICT with intravenous albumin paclitaxel (260mg/m 2 ), cisplatin (75mg/m 2 ) and Toripalimab (240mg) on day 1 and day 22; or three cycles of NAITT with intravenous Camrelizumab (250mg) on d1, d15, d29, and oral Apatinib daily, initiating on d1, ending on the 5th day before surgery. Then, radical surgery and post-operative radiotherapy/chemoradiotherapy was performed. Primary tumors were assessed for the percentage of residual viable tumor that was identified on HE staining, and tumor with no more than 10% viable tumor cell was considered as MPR. Results: From April 2020 to April 2021, 40 patients received NAIT and radical surgery. The rate of CPS>10 in the biopsy and the MPR rate was 20% and 60% in the NAICT group, 24% and 40% in the NAITT group, respectively. The follow-up period ranged from 45 to 53 months. The 4-year OS and DFS rate was 90% and 85% in the NAICT group, 90% and 80% in the NAITT group. In the patients archived MPR, the 4-year OS and DFS rate was 100% and 95%, in the non-MPR patients, the 4-year OS and DFS rate was 80% and 70%. In the nine patients with CPS>10, they were all alive without local tumor recurrence or metastasis. Conclusions: NAICT and NAITT are safe and effective, the LAOSCC patients with CPS>10 or archiving MPR could have long-term survival benefit from NAIT. Clinical trial information: NCT04473716 , NCT04393506 .