26P Efficacy and safety of tislelizumab combined with concurrent chemoradiotherapy for high risk locally advanced cervical cancer

Concurrent chemoradiotherapy (CRT) is the standard treatment for new diagnosis locally advanced cervical cancer (LACC). However, local recurrence and distant metastasis are the main modes of CRT failure in LACC, especially for the patient with high risk such as stage IIIA ∼IVA, tumour with large masses (>4cm) or regional lymph node metastasis. Here is a prospective, single-arm, phase II study aims to evaluate the efficacy and safety of tislelizumab (anti-pd-1 antibodies) combined with concurrent chemoradiotherapy for high risk LACC. Eligible patients were age 18-75 years with ECOG PS 0-1, histologically confirmed cervical cancer with 2018 FIGO stage IIIA, IIIB, IVA or cervical tumors > 4cm with regional lymph node metastasis, or paracervical invasion with regional lymph node metastasis, and without received prior systemic therapy, surgery or radiation. All patients received CRT combined with tislelizumab 200mg Q3W for 1 year or until disease progression or intolerable toxicity. The CRT includes at least 4 cycles of cisplatin 40mg/m2/W + EBRT 45∼50Gy/25f then BT 28∼30Gy/4∼5f. The primary endpoint was tumor regression ratio after EBRT. Secondary endpoints were 3-month and 6-month ORR after CRT, 1-year and 3-year OS and PFS, safety. Until Feb,28, 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 after EBRT was 90.6%. The 3 and 6-months ORR after CRT were 100% and 100%. The 1-year PFS rate was 100%. The main adverse effect was neutropenia including 36% for grades 3-4 and 20% for grades 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. Our results suggest that Tislelizumab combined with concurrent chemoradiotherapy showed valuable antitumor activity and controllable safety in high risk LACC. The combination regimens can be one of the treatment options for these patients.