This insertion enables local expression of GM-CSF at the tumor site, recruiting antigen-presenting cells (APCs) such as dendritic cells (DCs) and inducing downstream T-cell activation.316 In addition to melanoma, T-VEC’s effects on breast cancer, sarcoma, and head and neck squamous cell carcinoma are being evaluated in clinical trials, with initial results reported.317–319. The gene discussed is CSF2; the disease is melanoma.