Radiation Therapy Plus Anti-Programmed Death Ligand 1 Immunotherapy: A Review on Overall Survival.

PURPOSE: To analyze current preclinical trials and early clinical trials on the effects of concomitant anti-programmed death ligand 1 (anti-PD-L1) immunotherapy and radiation therapy on progression-free survival (PFS) and overall survival (OS) for advanced melanoma and metastatic non-small cell lung cancer (NSCLC) patients.

METHODS: A literature review was conducted to find current articles about radiation and anti-PD-L1 combinatorial therapy to gain knowledge about T-lymphocyte (T-cell) mediated immune responses, preclinical mouse tumor trials, and early clinical trials.

RESULTS: Several preclinical studies involving mice tumor strains and 2 early clinical trials observed an increase in PFS and OS when testing radiation therapy given in combination with anti-PD-L1 immunotherapy. Abscopal effects of tumor regression and control were notable in some studies.

DISCUSSION: Low doses of radiation enhance the immune system by increasing T-cell activity. Radiation also increases levels of PD-L1 that inhibit tumor-fighting capabilities of T-cells. Anti-PD-L1 immunotherapy given in combination with radiation therapy has been tested in preclinical studies and hypothesized to increase PFS and OS in patients with advanced melanoma and metastatic NSCLC.

CONCLUSION: Anti-PD-L1 immunotherapy boosts the immune effects of radiation therapy on tumor regression by eradicating the limiting effects of PD-L1 on the immune system. The combination therapies have the potential to benefit metastatic patients who qualify for the treatment.