Anatomic Location Predicts Response Rates: Real World Outcomes With Over 1100 Cycles of Talimogene Laherparepvec Description: A Retrospective Review of a Prospectively Maintained Database.

Abstract

We hypothesized that anatomic location of metastatic melanoma is associated with the degree of therapeutic response to talimogene laherparepvec (TVEC). TVEC is the first FDA-approved injectable oncolytic virus to treat unresectable stage IIIB-IV metastatic melanoma patients. Previously published real-world outcomes demonstrated a 39% complete response (CR) rate to TVEC. A prospective single-center melanoma database of patients treated with TVEC from December 2015 to December 2023 was analyzed. Patients were categorized into groups based on treated anatomic sites. Patient characteristics were summarized using frequencies, means, medians, comparisons, and tests of proportions using χ 2 , Fisher exact, and Wilcoxon rank sum tests. We used unadjusted generalized estimating equation models with repeated measures to estimate relative risk ratios for local treatment response and anatomic sites. One hundred seventy-three patients were included: median age 75 years; majority male (n = 112, 64.7%) and white (n = 170, 98.3%). We analyzed 190 therapeutic plans of TVEC with a total of 1133 cycles, median 6 cycles/patient (1 to 18). Median follow-up was 41 months (11 to 107). Of the anatomic sites treated, 73 were head/neck (38.4%), 73 lower extremity (38.4%), 25 torso (13.2%), and 19 upper extremity (10%). CR was seen in 79 (41.6%), partial response (PR) in 41 (21.6%), mixed response/stable disease in 37 (19.5%), and disease progression in 33 (17.4%). In the CR group, 40 (50.6%) responses were head/neck, 24 (30.4%) lower extremity, 11 (13.9%) torso, and 4 (5.1%) upper extremity. This is the largest prospective cohort evaluating real-world outcomes of metastatic melanoma patients treated with TVEC based on anatomic location. TVEC is a well-tolerated, durable treatment for advanced-stage melanoma. Our findings demonstrate head/neck metastases have the greatest CR rate and should be considered as a possible first-line therapy in select patients.