Radiotherapy and immune checkpoints inhibitors for advanced melanoma

Abstract

Introduction: The therapeutic landscape of metastatic melanoma drastically changed after the introduction of targeted therapies and immunotherapy, in particular immune checkpoints inhibitors (ICI). In recent years, positive effects on the immune system associated to radiotherapy (RT) were discovered, and radiation has been tested in combination with ICI in both pre-clinical and clinical studies (many of them still ongoing). We here summarize the rationale and the preliminary clinical results of this approach.

Materials and methods: In the first part of this review article, redacted with narrative non-systematic methodology, we describe the clinical results of immune checkpoints blockade in melanoma as well as the biological basis for the combination of ICI with RT; in the second part, we systematically review scientific publications reporting on the clinical results of the combination of ICI and RT for advanced melanoma.

Results: The biological and mechanistic rationale behind the combination of ICI and radiation is well supported by several preclinical findings. Retrospective observational series and few prospective trials support the potential synergistic effect between radiation and ICI for metastatic melanoma.

Conclusion: RT may potentiate anti-melanoma activity of ICI by enhancing response on both target and non-target lesions. Several prospective trials are ongoing with the aim of further exploring this combination in the clinical setting, hopefully confirming initial observations and opening a new therapeutic window for advanced melanoma patients.

Keywords: Immunotherapy; Melanoma; Radiotherapy; Stereotactic radiotherapy.