Graft versus host desease as a rare and seriously side effect of anti-PD-1 inhibitor immunotherapy

of patients with focal treatment by stereotactic radiotherapy (SBRT) of hepatic lesions.Methods: A retrospective evaluation of hepatic oligometatases treated by SBRTat 2 centres in France between 2007 and 2020 with a maximum of 3 lesions before treatment.The primary objective was to assess local control (LC) of melanoma metastases after SBRT treatment.Efficacy and toxicity data were collected.Results: Sixteen patients were treated.Of these, 5 patients showed oligoprogression (30%), 1 patient showed oligopersistence under treatment (6%) and 6 patients showed oligorecurrence (35%).The melanomas were cutaneous (10; 59%), mucosal (1; 6%), uveal (2; 12%) or of unknown origin (4; 24%).Nine patients (53%) received concomitant treatment with irradiation, 7 with immunotherapy (78%) and 2 with anti BRAF and MEK targeted therapy (22%).Of the patients without concomitant treatment: 3 had already been treated with immunotherapy, 5 had not received immunotherapy (prior to unavailability or contraindication).The median duration of treatment before irradiation was 14 months (5 to 52 months).The median dose received was 45 Gy in 3 fractions (27 to 54 Gy). 4 patients experienced grade 1 or 2 nausea or abdominal pain.No patient experienced a grade 3 adverse event.After a median followup of 29 months (5 -81 months), 2 patients had a relapse of the treated lesion (12%), 11 patients had distant relapses (65%).The best response obtained per lesion treated was a complete response in 9 patients (53%), a partial response in 3 patients (18%), 3 stabilisations (18%) and 2 progressions (12%) according to RECIST1.1 criteria.Mean progression-free survival was 16 months (3 to 50 months) and overall survival 59 months (17 to 182 months).Six patients died during follow-up (35%), all due to melanoma progression.Conclusions: Our study suggests that hepatic radiotherapy provides good local control of treated hepatic lesions, with good tolerability in patients with hepatic metastatic melanoma with or without associated systemic therapy.Further randomised studies are needed to establish the role of radiotherapy in therapeutic strategies for patients with hepatic metastatic melanoma.