Emerging evidence for adapting radiotherapy to immunotherapy

Cet article passe en revue les études pré-cliniques et cliniques sur les traitements combinant radiothérapie et immunothérapie puis identifie des stratégies pour adapter les différents paramètres de la radiothérapie (dose, nombre de fractionnements, tissus ciblés, ...) aux spécificités de l'immunothérapie et améliorer ainsi l'efficacité de la combinaison thérapeutique

Résumé en anglais

Immunotherapy has revolutionized the clinical management of many malignancies but is infrequently associated with durable objective responses when used as a standalone treatment approach, calling for the development of combinatorial regimens with superior efficacy and acceptable toxicity. Radiotherapy, the most commonly used oncological treatment, has attracted considerable attention as a combination partner for immunotherapy owing to its well-known and predictable safety profile, widespread clinical availability, and potential for immunostimulatory effects. However, numerous randomized clinical trials investigating radiotherapy–immunotherapy combinations have failed to demonstrate a therapeutic benefit compared with either modality alone. Such a lack of interaction might reflect suboptimal study design, choice of end points and/or administration of radiotherapy according to standard schedules and target volumes. Indeed, radiotherapy has empirically evolved towards radiation doses and fields that enable maximal cancer cell killing with manageable toxicity to healthy tissues, without much consideration of potential radiation-induced immunostimulatory effects. Herein, we propose the concept that successful radiotherapy–immunotherapy combinations might require modifications of standard radiotherapy regimens and target volumes to optimally sustain immune fitness and enhance the antitumour immune response in support of meaningful clinical benefits.