Abstract

The introduction of immune checkpoint inhibitors (ICI), such as anti-PD1, anti-PDL1 and anti-CTLA4, has shown clinically significant benefit in prospective randomized clinical trials across many tumor types. In recurrent/metastatic head and neck squamous cell cancer ICIs have overall response rates ~13-18%. The realization that radiotherapy may induce out-of-field immune-related effects, known as abscopal, by acting as an “in-situ”vaccine has led the research to combined radioimmunotherapy studies. In this short review we follow the abscopal effect from its first case report to the present and contemplate on how the delivery of radiotherapy could be optimized to maximize the probability of its occurrence.

Keywords

immune-mediated responses, normal organs, tumors, abscopal effect, nivolumab, oropharyngeal and hypopharyngeal cancer, distant metastatic, neoantigens, in-situ vaccination, necrosis, radioimmunotherapy interventions, synergism, Treg cells, randomization