Evaluating the combination of two immune system-stimulating drugs for the treatment of patients with metastatic melanoma

This phase 3 clinical trial evaluated the safety and efficacy of a combination of drugs that stimulate the immune system (interleukin-2 and the gp100 vaccine) in patients with metastatic melanoma. 

A metastasized melanoma is cancer of the pigmented cells (called ‘melanocytes’) of the skin that has spread to other tissues and organs of the body. Patients with metastatic melanoma typically have low rates of survival, but new drugs are being researched which may help to increase those rates. Interleukin-2 (Proleukin) is a drug which helps the immune system fight cancer cells the same way the body fights an infection. This drug on its own has shown to improve survival rates in patients with metastatic melanoma. A new treatment for melanoma currently being studied is the gp100 vaccine, which increases the amount of cancer killing cells in the immune system. The current study evaluated whether the combination of the two immune system-stimulating drugs has any benefits in term of survival compared to interleukin-2 alone.

This study included 185 patients with metastatic melanoma. Patients were randomly assigned to receive either interleukin-2 alone (94 patients), or the gp100 vaccine followed by interleukin-2 (91 patients). The patients completed between 1 and 10 cycles of treatment, and were given up to 12 doses in a cycle. All patients were evaluated every 6 weeks for response to the treatment (a decrease in cancer progression). Patients who received both the gp100 vaccine and interleukin-2 showed a significantly higher response to treatment (20%) than did patients who were given only interleukin-2 (10%). Progression-free survival (the time without the cancer progressing after starting treatment) was higher in patients receiving the combined treatment (2.2 months) than in patients treated with interleukin-2 alone (1.6 months). The average overall survival (defined as the time patients survived since treatment) was also higher in patients in the combined treatment group (17.8 months) than in the group receiving interleukin-2 alone (11.1 months). However, side effects such as irregular or rapid heartbeat were more common in the combined treatment group.

In summary, this study showed that the combination of the gp100 vaccine and interleukin-2 increased the response to treatment and survival rates compared to interleukin-2 alone in patients with metastatic melanoma.

This study was partly funded by Novartis, the manufacturer of Proleukin.