Prospects for gene therapy and lymphokine therapy for metastatic melanoma

Conventional treatment of cancer, especially for patients with metastatic melanoma tumor, is often ineffective. Immunotherapy and recently introduced gene therapy have revolutionized the treatments of patients with metastatic melanoma tumor. Use of biological response modifiers, such as interleukins and interferons, have been found to enhance therapeutic benefits to patients with malignant melanoma. Initial studies with a high-dose interleukin-2 (IL-2) therapy have proved effective in patients with melanoma tumor, although a variety of systemic toxicities were observed. A low-dose IL-2 continuous infusion has shown a similar response in patients with melanoma tumor, but produced lesser toxicity. The low-dose IL-2 therapy has been studied with an adoptive transfer combined with either autologous lymphokine activated killer cells or autologous tumor infiltrating lymphocytes (TIL). IL-2 in combination with chemotherapeutic agents such as flavone acetic acid, dacarbazine, and cyclophosphamide have also been studied in patients with metastatic melanoma. Results have shown a moderate response in patients with metastatic melanoma. TIL therapy, however, has been shown to result in higher objective regression due to potent tumor-specific killing and tumor-specific targeting characters of the TIL. The tumor targeting nature of the TIL creates the possibility of using TIL as a vehicle to deliver gene product specifically to tumor tissue. Safety and toxicity of gene-transduced TIL were addressed by the use of neomycin-resistant, gene-transduced TIL in patients with metastatic melanoma. We also investigated the use of vaccinia oncolysate therapy by using the viral oncolysate prepared with IL-2 gene encoded vaccinia virus. Preliminary studies with murine hepatic metastases colon model have shown encouraging results.