Clinical and Histological Response to Talimogene Laherparepvec Therapy in Advanced Melanoma: Impact on Overall Survival

Abstract

Background: Talimogene Laherparepvec (T-VEC) is an FDA-approved oncolytic herpes virus therapy used for unresectable stage IIIB through IV metastatic melanoma. However, the correlation between clinical complete response (cCR) and pathologic complete response (pCR) in T-VEC-treated patients is understudied. Study Design: We conducted a retrospective study from a prospectively maintained IRB-approved melanoma single center database in patients treated with T-VEC from October 2015 to April 2022. Patients were categorized into three groups: cCR with pCR, cCR without pCR, and less than cCR. The primary endpoint was overall survival. We used descriptive statistics, Chi-Square tests, and Wilcoxon Rank Sum tests to compare key covariates among exposure groups. We used survival analysis to compare survival curves and reported hazard ratio of death, 95% confidence intervals (CI) across exposure groups. Results: We included 116 patients with a median overall survival of 22.7 months, interquartile range (IQR) (14.8, 39.3). The majority were male (69.0%) and white (97.4%), with a median age of 74.5 years. Over half of (n=60, 51.6%) patients achieved cCR. Distribution among the groups was as follows: cCR with pCR (35.3%), cCR without pCR (16.3%), and less than cCR (48.4%). Median overall survival time (IQR) was 26.5 months (18.6, 36.0) for cCR with pCR, 22.7 months (14.4, 35.5) for cCR without pCR, and 17.8 months (9.2, 47.0) for less than cCR(log-rank p-value = 0.0033). Conclusion: Patients achieving cCR with pCR following T-VEC therapy have the most favorable overall survival outcomes. Those with cCR without pCR have inferior survival, while less than cCR patients have the poorest overall survival outcomes. These findings emphasize the importance of histological confirmation and provide insights for optimizing TVEC therapy in advanced melanoma patients.