Teresa M. Petrella, M.D., of the Sunnybrook Odette Cancer Centre in Toronto, and colleagues conducted a phase 2, multicenter study to evaluate the efficacy and safety of IL-21 in patients with metastatic melanoma. Two of the groups received either 30 µg/kg per day (30 patients) or 50 µg/kg per day (three patients) by intravenous bolus for five days of each week during weeks one, three, and five of an eight-week cycle. A third group received 50 µg/kg per day (seven patients) for five days of each week during weeks one and three of a six-week cycle.

The researchers found that treatment-related adverse events included fatigue, rash, diarrhea, nausea, and myalgia. The ORR was 22.5 percent, with nine partial responses and 16 with stable disease. Median duration of response for all responders was 5.3 months. Response was not dependent on either BRAF mutation status or IL-21 receptor expression. Overall, median progression-free survival was 4.3 months and median overall survival was 12.4 months.

"Promising antitumor activity was observed at both doses and schedules used in this trial, although the numbers treated are too small for definitive comparisons to be made," the authors write. "Responses were seen at all disease sites, including skin, lymph nodes, lung, liver, and other visceral organs."

Two study authors disclosed receiving research funding from ZymoGenetics.

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