Therapeutic Implications of UVB Irradiation in Cancer by Enhancing Anti‐Tumor Immunity^†

Abstract

The UVB irradiation is well known for its impact on the development of skin cancer. However, low UVB irradiation plays a protective role against various human diseases including cancer through its effect on tumor suppression. This article summarizes the key findings of the paper by Park et al., which describes a novel molecular mechanism of moderate UVB irradiation in suppressing the growth of melanoma and colorectal cancer. Key observations in this article are that moderate UVB irradiation can enhance tumor immunity by (1) increased infiltration of CD4+ and CD8+ T cells; (2) increased infiltration of CD103+ conventional type 1 dendritic cells (cDC1); and (3) a significant decrease of M2 tumor associate macrophages (TAMs) into the tumor. The authors further identified the role of Batf3 transcription factor in moderate UVB irradiation‐mediated anti‐tumor immune response. Deletion of Batf3 transcription factor reversed the tumor suppressive effect with decreased CD103+ cDC1 cell infiltration. This pre‐clinical study provides a very novel mechanistic insight into the utilization of moderate UVB irradiation for the management of melanoma and colorectal cancer. This study further provides the direction of new future research to explore moderate UVB irradiation in combination with checkpoint blockade antibodies to enhance immunotherapeutic response against various solid tumors.