e22003 Background: Talimogene laherparepvec (TVEC) is an oncolytic herpes virus approved by the FDA for intralesional therapy in unresectable metastatic melanoma. However, little is known regarding the effectiveness of TVEC+checkpoint inhibition (CPI) outside of clinical trials. We present outcomes of the largest single institution experience with TVEC in the context of different immune checkpoint inhibitors. Methods: All patients with stage III-IV unresectable melanoma having received TVEC were evaluated. Patient demographics, clinicopathological characteristics, TVEC treatment response and outcomes were assessed. Final analysis included those who received TVEC adjacent to CPI with a minimum 6-month follow-up, excluding patients on clinical trials. Response was estimated by sequential measurement of injectable on-target lesions. Results: A total of 62 patients received TVEC from 2016 to 2019, of which 43 remained excluding Merkel cell carcinoma, patients on trials, and TVEC monotherapy. Of 30 patients with available treatment response data and at least 6-months follow-up, median age was 68.5 years (30-99 years), 40% were female, 16 (53.3%) stage IV. Median follow-up was 17.5 months (6-43 months). At 6 months, 20 (67.7%) patients were alive; at 1 year, 17 (56.7%) patients were alive. Eighteen patients received pembrolizumab, 7 nivolumab and 5 ipilimumab/nivolumab. Median number of TVEC doses received was 8 (3-31 doses). Median time on TVEC therapy was 4 months (1-26 months). Overall response rate for on-target lesions was 24 (80%), with complete local response (CR) in 15 (50%), partial response (PR) in 9 (30%), and progressive disease (PD) in 6 (20%). Median time to response was 6 weeks (2-17 weeks); 5 in CR, 6.5 in PR and 5.5 in PD groups. Adverse events were mostly mild and limited to constitutional symptoms. Conclusions: To our knowledge this is the largest real-world experience assessing TVEC in patients receiving CPI. Local overall response rate appears higher in comparison to historic numbers for TVEC monotherapy. The findings demonstrate that TVEC is an effective and safe treatment for metastatic melanoma and has robust outcomes in real-life clinical settings.