Approved by the FDA in 2015, T-VEC (abbreviated from talimogene laherparepvec) is the first therapeutic cancer vaccine based on an oncolytic virus. Examples of oncolytic viruses include adenoviruses, herpes simplex virus (HSV), and vaccinia virus (VACV). T-VEC is a genetically modified version of the herpes virus used to treat advanced-stage melanoma that fails to be thoroughly surgically removed. The vaccine is injected into the tumor under the skin or in the lymph nodes. Once delivered into the tumor, T-VEC undergoes high rounds of replication inside late-stage melanoma cells, so much so the vaccine causes tumor cells to burst (literally), which attracts host immune cells to arrive at the tumor site for tumor cell elimination.
As for treatment efficacy, the 5-year relapse-free survival (RFS) for patients who received T-VEC therapy before tumor surgical removal was 22.3%. By contrast, patients who did not receive T-VEC therapy before surgery had RFS of 15.2%.14
14. Melanoma Research Alliance. "T-VEC." Curemelanoma.org website. Last updated August 2021.https://www.curemelanoma.org/patient-eng/melanoma-treatment/immunotherapy/t-vec-imlygic
