9590 Background: Until recently, most patients (pts) with SLN+ MEL underwent CLND, a procedure mandated in published trials of adjuvant anti-PD-1 therapy to date. Following MSLT-II, this practice has dramatically changed with most pts now undergoing surveillance or adjuvant therapy without CLND. In addition, pts with in-transit/satellite MEL were excluded or not reported in these prior adjuvant studies. Our aim was to explore real-world outcomes of adjuvant NIVO in these pts. Methods: We carried out a single center retrospective analysis of stage 3 MEL pts who received adjuvant NIVO. Results: 32 pts with SLN+ MEL who did not undergo a CLND and started adjuvant NIVO within 3 months of surgery were included. Median age was 60 (26-77); per AJCC v7, 12 pts had Stage 3A, 11 stage 3B, and 9 pts had Stage 3C MEL. One was acral MEL; 18 had an ulcerated primary. 6 pts had BRAF-mutant MEL, 20 had BRAF-WT, and 6 unknown. NIVO treatment was 240 mg Q2wks or 480 mg Q4wks, up to one year. 21 pts developed grade 1/2 immune-related adverse events (irAEs), and 1 pt stopped NIVO due to toxicity (fatigue). With median follow-up of 7 months, only 1 pt had a recurrence, which was in the in SLN+ nodal basin; pt was rendered disease-free with surgery. The relapse-free rate (RFS) rate at 1 year was 95% (95% CI, 71-100). Of 21 pts with in-transit/satellite recurrent MEL (median age 68 [29-84]) who started adjuvant NIVO (no prior drug treatment), 5 had BRAF-mutant MEL, 14 BRAF-WT, 2 unknown; two were acral-lentiginous. 3 pts had recurrences: 2 regional and 1 distant mets, treated with surgery, TVEC, or BRAF-targeted therapy. Median follow-up was 8 months from NIVO start; 1-year RFS was 72% (95% CI 32-91). 15 pts developed irAEs; in 12, these were grade 1-2 and in 3, were grade 3 that led to discontinuation. Conclusions: While preliminary, these findings suggest that adjuvant anti-PD-1 therapy may be effective in SLN+ pts who forego CLND prior to adjuvant treatment, as 1-year RFS rate appears similar to rates in the published adjuvant anti-PD-1 trials that mandated CLND. This therapy may be similarly effective in pts with resected in-transit/satellite stage 3 melanoma. Further follow-up will be presented.