Phase II study of tislelizumab combined with concurrent chemoradiotherapy for locally advanced cervical cancer.

e17523 Background: Concurrent chemoradiotherapy (CRT) is the standard treatment for locally advanced cervical cancer (LACC). However, local recurrence and distant metastasis are the main modes of treatment failure in LACC, especially for patients with stage IIIA ~IVA as well as patients with large masses (>4cm) and regional lymph node metastasis. This study aimed to evaluate the efficacy and safety of tislelizumab (anti-PD-1 antibody) combined with concurrent chemoradiotherapy for locally advanced cervical cancer. Methods: Eligible patients were age 18-75 years, ECOG performance status of 0-1 and untreated cervical cancer (2018 FIGO stage IIIA, IIIB, IVA, or cervical tumor diameter > 4cm with regional lymph node metastasis, or paracervical invasion with regional lymph node metastasis). All patients received CRT plus tislelizumab 200mg Q3W for 1 year or disease progression or intolerable toxicity. The CRT includes at least 4 cycles of cisplatin 40mg/m 2 QW + EBRT 45~50Gy/25f then BT 28~30Gy/4~5f. The primary endpoint was tumor regression ratio before brachytherapy. Secondary endpoints were 3-month and 6-month objective response rate (ORR), 1-year and 3-year OS and PFS, safety. Results: From August 24, 2022 to February 4, 2024, 30 patients were enrolled. 25 patients completed CRT and were available for evaluation. The median age was 59 years (range 40-75). The tumor regression ratio before brachytherapy was 90.6%. The ORR at 3 and 6 months were 100%, The OS and PFS rate at 1 year were 100%. The main adverse effect was neutropenia (36% for grade 3-4 and 20% for grade 1-2). Radiation enteritis incidence was 64% and were grade 1-2. Other adverse effect such as nausea, vomiting, and dizziness occurred during CRT and could be alleviated after symptomatic treatment. No immune-related adverse events were observed. Conclusions: Our results suggest that Tislelizumab combined with concurrent chemoradiotherapy showed valuable antitumor activity and controllable safety in LACC. We will keep strictly implementing our study protocol for further PFS and OS. Clinical trial information: NCT05588219 .