ESTRO 2024 - Abstract Book

S1381

Clinical - Head & neck

ESTRO 2024

Shuohan Zheng 1,2 , Ya Liu 1,2 , Zhigang Liu 3 , Jin Gao 4 , Liying Gao 5 , Ming Zhang 5 , Yuandong Cao 6,7 , Shu Zhou 6,7 , Jinbo Wu 8 , Li Xiang 8 , Zilu Huang 1,2 , Ying Wang 1,2 , Shuiqing He 1,2 , Chen Chen 1,2 , Yalan Tao 1,2 , Songran Liu 1,2 , Ping Feng 1,2 , Yunfei Xia 1,2 1 Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China, Guangdong Key Laboratory of Nasopharyngeal Carcinoma Diagnosis and Therapy, Guangdong Provincial Clinical Research Center for Cancer, Guangzhou, China. 2 Sun Yat-sen University Cancer Center, Department of Radiation Oncology, Guangzhou, China. 3 Dongguan People's Hospital (Affiliated Dongguan Hospital to Southern Medical University), Cancer Center, Dongguan, China. 4 The First Affiliated Hospital of University of Science and Technology of China, Department of Radiation Oncology, Anhui, China. 5 Gansu provincial Cancer Hospital, Department of Radiation Oncology, Lanzhou, China. 6 The First Affiliated Hospital of Nanjing Medical University, Department of Radiation Oncology, Nanjing, China. 7 Nanjing Medical University, The First School of Clinical Medicine, Nanjing, China. 8 Affiliated Hospital of Southwest Medical University, Department of Oncology, Luzhou, China

Purpose/Objective:

In the first-line treatment of metastatic nasopharyngeal carcinoma, which chemotherapy regimen is more effective when combined with immunotherapy? In this multicenter, open, randomized trial, we wanted to compare the advantages of low-dose and long-term 5-fluorouracil instead of gemcitabine in combination with the immune checkpoint inhibitor in cisplatin-based chemotherapy.

Material/Methods:

From 14 July 2021 to 18 October 2023, a total of 44 eligible patients who had never previously received systemic treatment for metastatic nasopharyngeal carcinoma were enrolled and randomized 1/1 to the treatment group and the control group at 5 partner hospitals in China. The treatment group was treated with toripalimab and low-dose, long-term 5-fluorouracil and cisplatin (PFLL arm) every 60 days, and the control group was treated with toripalimab and gemcitabine and cisplatin (GP arm) regimen every 21 days. The combination treatment of two groups was up to 6 cycles, followed by toripalimab monotherapy for a total treatment duration of 2 years, voluntary withdrawal, disease progression, or death. 21 patients were assigned to the PFLL arm and 23 patients were assigned to the GP arm. The primary endpoint was progression-free survival (PFS) as assessed according to RECIST v.1.1.

Results:

The baseline demographic and disease characteristics were generally balanced between the two arms, including sex, age, metastasis sites and numbers of metastasis. The median follow-up time was 13.5 months and 9 deaths had been reported (5 patients in the GP arm and 4 in the PFLL arm). Seven patients (33.3%) in the PFLL arm achieved complete response (CR), significantly higher than 3 patients (13.0%) in the GP arm (P=0.04). Three patients (14.3%) in the PFLL arm and 6 (26.1%) in the GP arm achieved partial response (PR). The objective response rate (ORR) was 47.6% (10/21) in the PFLL arm and 39.1% (9/23) in the GP arm. The disease control rate (DCR) was 100% (21/21) in the PFLL arm and 88.0% (20/23) in the GP arm. Both ORR and DCR had no difference between the two arms (P=0.57, P=0.09). The median PFS and overall survival (OS) of the two groups did not reach. The common treatment-emergent adverse event (TEAEs) included leukopenia (87.0% in the PFLL arm vs 85.7% in the GP arm), anemia (71.4 vs 91.0%), neutropenia (42.9 vs 82.6%), thrombocytopenia (28.6 vs 30.3%), hyponatremia (57.0 vs