A randomized controlled study of tislelizumab combined with concurrent chemoradiotherapy in the treatment of locally advanced cervical cancer and the predictive value of T lymphocyte subsets for efficacy.

Abstract

2615 Background: Concurrent chemoradiotherapy (CCRT) has been the standard of care for locally advanced cervical cancer (LACC) for over 20 years. However, 30-40% of treated patients have recurrence or progression within 5 years. Methods: A total of 53 patients with LACC who were treated in the First Affiliated Hospital of Guangxi Medical University from May 2023 to November 2024 were prospectively collected and randomly divided into the CCRT group (N = 26) and the CCRT+T group (N = 27). The treatment plan was as follows: 200 mg of tislelizumab was intravenously infused on the first day of radiotherapy, once every 3 weeks, for 1 year or until disease progression or intolerable toxicity, whichever occurred first. Chemotherapy involved single-agent cisplatin at a dose of 40 mg/m 2 . External irradiation used 6MV-X-ray intensity-modulated radiotherapy with a dose of 45-50Gy/25f. Simultaneously, peripheral blood T lymphocyte subsets were detected in the enrolled patients before and at the end of radiotherapy. The primary endpoint of the study was the objective response rate, and secondary endpoints included toxicity, PFS and OS. Results: Follow-up was completed by January 2025, with a median follow-up time of 13.7 months (5.2-20.5 months) in the CCRT group and 11.2 months (5.9-20.6 months) in the CCRT+T group. The CCRT+T group had higher complete response (CR) and objective response rates (ORR) compared to the CCRT group, with CR rates of 44.4% versus 19.2% (p = 0.035) and ORR rates of 100% versus 84.6% (p = 0.046). The patients with CR were subjected to logistic regression analysis. The results of univariate and multivariate analysis showed that CD4+T cell percentage (p = 0.034) and tislelizumab use (p = 0.038) were significantly associated with CR. However, no statistical difference was observed in the OS (p = 0.414) and PFS (p = 0.716) between the two groups, as shown by the Kaplan-Meier survival curves. After treatment, the CCRT+T group had increased levels of total T cell percentage, CD4+T cell percentage, CD4/CD8, double positive T lymphocyte subset percentage, absolute T lymphocyte count, absolute CD4+T lymphocyte count, and B lymphocyte (CD19) compared to the CCRT group. Notably, the double positive T lymphocyte subset percent (p = 0.025) and absolute CD4+T lymphocyte count (p = 0.047) showed significant increases. There was no significant difference in the incidence of acute adverse reactions between the two groups (P > 0.05). Conclusions: CCRT+T demonstrated superior short-term efficacy in treating LACC compared to CCRT, although long-term efficacy necessitates further follow-up observation. The combination of tislelizumab and CCRT in the treatment of LACC can improve the levels of T cell subsets, with tolerable acute toxic and good safety. CD4+T cell percentage and tislelizumab use may be associated with CR.