Radiotherapy Improves Antitumor Immunity by Inducing Immunogenic Cell Death in Breast Cancer Patients.

[BACKGROUND] Radiotherapy, a significant cancer treatment, stimulates localized tumor cell death and causes immune modulation. Increasing data has indicated that radiation strengthens tumor-related immunity.

[AIM OF THE STUDY] The aim of this work was to investigate the effect of radiotherapy on soluble forms of the primary immune checkpoints CTLA-4, PD-1 and PD-L1 in patients with breast cancer.

[PATIENTS AND METHODS] The study was conducted on70 subjects were separated into 2 groups: Group I included 40 patients with breast cancer who received fractionated radiation. Group II: Includes 30 healthy females free from any disease as control group, age and gender matched the patients' group. ELISA was used to assay CTLA-4, PD-1 and PD-L1.

[RESULTS] The current study revealed that soluble PD-1 and PD-L1 are significantly elevated in sera of patients with breast cancer pre radiotherapy treatment and significantly higher than in control group. Exposure to radiotherapy significantly drops PD-1 levels and brings its levels in patients closer to those of healthy individuals but not affects PD-L1 levels. Soluble CTLA-4 is insignificantly elevated in sera of breast cancer patients pre radiotherapy treatment and significantly decreased post radiotherapy.

[CONCLUSION] Radiotherapy can enhance immune recognition of the tumor cells by dropping the primary immune checkpoints PD-1 and CTLA-4 in breast cancer patients and improve response to immune checkpoints inhibition.