Survival outcomes of concurrent radiotherapy and toripalimab versus radiotherapy alone for elderly patients with postoperative head and neck squamous cell carcinoma unfit for cisplatin.

Abstract

6099 Background: For elderly patients with locally advanced head and neck squamous cell carcinoma (HNSCC), the role of postoperative concurrent chemotherapy was controversial since the intolerable toxicities and increased acute mortality, thus, radiotherapy alone was recommended. We aimed to assess if addition of toripalimab (anti-PD-1) to radiotherapy could improve treatment outcomes for this patient population. Methods: This trial was an, open-label, phase 2, randomized study.We randomly assigned (1:1) patients aged>65 years, with ECOG Performance Status(PS) of 0–2, and with postoperative Stage III-IV (AJCC 8th Staging system) HNSCC unfit for cisplatin to concurrent radiotherapy (60-66Gy) and toripalimab (240mg on D0, D21 and D42)(RT+PD-1 group) or radiotherapy alone(RT group). The primary endpoint was 2-year disease free survival (DFS). It is hypothesized to detect a difference between arms of 45%-65% in 2-year DFS. Results: Between September 2020 and May 2023, 87 patients were randomly assigned (43 in RT+PD-1 group and 44 in RT group). The median age were 71.0 years (range 66-81) for the RT+PD-1 group and 72.5 years (range 67-80 years) for RT group. In the RT+PD-1 group, 35 (81.4%) patients received at least one dose of toripalimab; 38 (88.3%) patients in the RT+PD-1 group and 36 (81.8%) patients in the RT group complete the planed radiation dose. Median follow-up was 24 months in both arms. The 2-year DFS was 55.3% with RT+PD-1 and 51.2% with RT alone (p=0.866), and the 2-year OS was 63.3% with RT+PD-1 and 78.4% with RT alone(p=0.557). In RT+PD-1 group, 18(41.8%) patients were CPS≥20%; 2-year DFS was 72.2% in patients with CPS≥20%, which was 53.8% in patients with CPS<20 (p=0.412). Conclusions: The primary objective of prolonging DFS with concurrent radiotherapy and toripalimab in elderly patients unfit for cisplatin with locally advanced HNSCC was not met. For patients with CPS≥20, further study still warranted to evaluate the benefit of toripalimab in this patient setting. Biomarker analysis is still ongoing. Clinical trial information: NCT04523883 .