Dynamics in the expression of programmed death ligand 1 and cluster of differentiation 163 in the tumor microenvironment of uterine cervical cancer: a single-center retrospective study

Abstract

Background: Radiotherapy (RT) destroys cancer cells and activates the immune system while suppressing the immunity of tumor-associated tissues, including the tumor microenvironment (TME). However, to date, no anti-tumor therapeutic strategy that uses these immune mechanisms has been established. This study investigated changes in the immunity of the TME during standard radical RT for cervical cancer combined with external beam RT and brachytherapy and determined whether these changes affect prognosis.

Methods: Twenty-six patients who had completed radical RT for cervical cancer were categorized into the following two groups according to whether the cancer recurred and/or metastasized within 2 years after the start of treatment: treatment failure (n = 14) and treatment success (n = 12). We assessed the expression of programmed death 1, programmed death ligand 1 (PD-L1), cluster of differentiation (CD) 8, CD68, CD163, Forkhead box protein P3, and hypoxia-inducible factor-1α in the TME of cervical tissues collected periodically during treatment and evaluated the difference in expression rates of each marker between the success and failure groups and assessed its effect on prognosis.

Results: The expression levels of PD-L1 and CD163 in the TME in the treatment success group were lower than those in the treatment failure group at the midpoint during brachytherapy (p < 0.01 and p = 0.08, respectively), and the 2-year progression-free-survival (PFS) rate depended on the expression levels of PD-L1 and CD163 (p = 0.04 and p = 0.02, respectively).

Conclusions: The expression rates of CD163 and PD-L1 in the TME during brachytherapy were related to treatment response and the 2-year PFS. This study may increase our understanding of tumor-associated immunity in the TME and aid in the development of therapies targeting PD-L1 or M2 macrophages in the TME in conjunction with RT, especially brachytherapy, for cervical cancer patients.

Keywords: Brachytherapy; Cluster of differentiation 163; External beam radiotherapy; Programmed death ligand 1; Tumor microenvironment; Uterine cervical cancer.