Malignant melanoma, the most serious form of skin cancer, is composed of cells derived from the foetal neural crests. Herpes simplex virus (HSV) is neurotropic virus and can therefore localise in melanoma cells. HSV variant 1716 replicates preferentially in human melanoma cell lines
In a preliminary study, Rona MacKie and colleagues tested the effects of intratumoral injection of HSV1716 into subcutaneous nodules of metastatic melanoma in five patients with advanced (stage 4) disease. For each patient, a test nodule was injected with103 pfu HSV1716, and a second nodule was injected with 1 ml sterile saline as a control. In one patient, flattening of previously palpable tumour nodules was seen 21 days after two direct injections of HSV1716. Nodules of all three patients who received two or more injections showed evidence of tumour necrosis (
MacKie comments: "This pilot study shows that HSV1716 replicates in melanoma cells, causes tumour-cell death if in direct contact with the melanoma cells, and is not toxic. The results are sufficiently encouraging to continue with higher doses of HSV1716 in patients with metastatic melanoma."