Efficacy and safety of stereotactic radiotherapy in hepatic oligometastatic melanoma

stopping ICI due to toxicity and treated with adjuvant ICI were excluded from the study.Data cut-off was 1/12/2024.Results: 227 (104F/123M) patients were enrolled including 147 BRAF(-) pts and 96/65/66 CR/PR/SD pts.106/101/20 patients received nivolumab/pembrolizumab/combination, respectively.139 pts were treated >/= 24 months (m) and 200 in the first line.At the median follow-up of 63.4 m since the first ICI cycle, median OS was not reached, 33 pts died, and the 5-year OS rate was 86.2%. OS during ICI drug holidays in pts treated < and >/= 24 monthsMedian ICI-drug holidays duration (PFS1) was not reached, 69 (30%) pts progressed, and the 5-year PFS1 rate was 70.9% for all patients.PFS1 rate was highest in CR group and in pts treated >/= 2 years before ICI-drug holidays.After ICI-drug holidays, the objective response rate to immunotherapy reinduction was 58%.Durable objective responses were achieved on post-drug holidays immunotherapy with PFS2=50.2 m in 59 pts who were retreated with ICI. Drug holidays duration -PFS1 -in pts with objective response and stable diseaseConclusions: ICI may be safely stopped in patients who achieved objective response during metastatic melanoma treatment.The best radiological response achieved before drug holidays correlated with ICI-drug holidays duration, with the longest duration of response without treatment for the complete responders.Immunotherapy treatment duration of at least 24 months improves long-term disease control and OS.