Treatment of metastatic malignant melanoma

Abstract

The rapid increase in incidence of malignant melanoma has not been associated with better therapeutic options over the years. Single-agent chemotherapy or immunotherapy remain the treatments of choice when systemic therapy is offered. Dacarbazine (DTIC) is the chemotherapy of choice with a response rate of 16%. Other chemotherapies, including cisplatinum, paclitaxel, docetaxel and the DTIC analogue temozolomide, have shown activity in this disease. Based on their single-agent activity, several combination chemotherapies have been investigated with preliminary results that appeared promising. However, in randomized phase III trials the two most active chemotherapy combination regimens, cisplatin, vinblastine, and DTIC (CVD) and the Dartmouth regimen (DTIC, cisplatin, bischloroethylnitrosourea , and tamoxifen), did not prove to be superior to single-agent DTIC for overall survival. Immunotherapy with either interleukin (IL)-2 or interferon (IFN) has demonstrated response rates of 10% to 15% in appropriately selected patients. In patients who achieve a complete response, responses can be of greater durability than those with chemotherapy. However, IL-2 and IFN administration are associated with multiple side effects, and only physicians experienced in the management of such therapies should administer them. The potential benefit of combining chemotherapy with immunotherapy has led to multiple phase II trials of biochemotherapy that appeared to be associated with higher response rates and longer median survivals. However, several phase III trials have been completed that have not consistently demonstrated an improvement in either response rates or overall survival, and these approaches to therapy cannot be routinely recommended outside the context of a clinical trial. The surgical resection of isolated metastatic disease has demonstrated an important palliative benefit in those patients who present with solitary single-organ disease with the exception of the liver. Radiation has an important role in the palliative management of brain metastasis and symptomatic bony metastasis. Both stereotactic radiosurgery and whole brain radiotherapy have been used alone and in combination to benefit patients in this troubling clinical circumstance. Isolated limb perfusion and a newer technique, isolated limb infusion have demonstrated high response rates for those uncommon patients who develop recurrent disease isolated to a limb. In our opinion, if complete metastasectomy is not feasible and in the absence of brain metastases, single-agent IL-2 is a good initial treatment choice in appropriately selected patients. Single-agent chemotherapy with DTIC is the treatment of choice for patients who are not candidates for IL-2. Adoptive immunotherapy combining nonmyeloablative chemotherapy with high-dose IL-2 is a potentially promising therapeutic strategy under investigation. Targeted therapy is also an area of promising development as single agents, in combination, and combined with chemotherapy. The latter will be the focus of at least one upcoming cooperative group phase III trial.