BACKGROUND: The concept of real option value (ROV) suggests there is added value in treatments that extend life because they enable a patient to live long enough to benefit from future innovative treatments. Real-world evidence of this novel value element is scant, limiting its consideration in formal value assessments. OBJECTIVE: To calculate the ROV in clinical practice of ipilimumab for treatment of advanced melanoma, with evaluation of survival until availability of cancer immunotherapy (CIT). METHODS: This was a retrospective analysis of electronic health records from a US nationwide deidentified database including data from approximately 280 cancer clinics. Participants were patients with advanced or metastatic melanoma diagnosed after January 1, 2011, who initiated treatment before April 19, 2015, and were treated with first-line and second-line ipilimumab or chemotherapy, up to availability of CIT. The proportions of patients surviving and receiving CIT and overall survival by line of therapy were calculated. Baseline demographics were used to weight Kaplan-Meier curves using stabilized inverse probability of treatment weighting. ROV was estimated for patients receiving first-line or second-line ipilimumab with or without subsequent CIT and first-line or second-line chemotherapy with or without subsequent CIT. RESULTS: Overall, 721 patients were included in the study, with a total sample size of 733 (12 patients in both groups). For first-line ipilimumab, 50% of patients survived to the availability of CIT, while only 18% of first-line chemotherapy users survived to the same date. For second-line ipilimumab, 37% of patients survived to availability of CIT vs 21% of patients using second-line chemotherapy. 45% of first-line ipilimumab and 52% of second-line ipilimumab patients who survived to the availability date received CIT. ROV for first-line ipilimumab averaged 3.7 months of additional survival, while those who initiated second-line ipilimumab averaged 4.8 months. The combined estimated ROV was 3.9 months. CONCLUSIONS: This study provides real-world evidence of ROV and adds to the growing literature that may support inclusion of this novel value concept for innovative therapies alongside more traditional measures of value. Further evaluation of ROV in clinical areas with varying survival and innovation is warranted. DISCLOSURES: This study was funded by Genentech, Inc., which was involved in conducting the study. Wong and To are employees of Genentech, Inc. Veenstra, Garrison, Li, and Lee have served as consultants to Genentech, Inc. Data were presented at ISPOR 2021; May 17-20, 2021; as a virtual podium presentation.