Comparison of acute toxicity and mortality after two different dosing regimens of high-dose interleukin-2 for patients with metastatic melanoma

We compared acute toxicity, drug exposure, in-hospital mortality, and inpatient length of stay between two currently recommended dosing protocols (from the National Comprehensive Cancer Network Guidelines) of high-dose interleukin-2 (IL-2) treatment for patients with metastatic melanoma. Patients with metastatic melanoma who received high-dose IL-2 treatment between 2003 and 2010 were identified. Chemotherapy orders, electronic medical records, paper medical charts, and patient discharge summaries were reviewed retrospectively. We identified 13 patients who had received 600,000 units/kilogram (kg)/dose and 15 patients who had received 720,000 units/kg/dose. Patients in the 720,000 units/kg/dose group had a higher rate of grade 3 and 4 bilirubin elevations (34 vs. 12 %), weight gain (any grade, 96 vs. 89 %), and thrombocytopenia (any grade, 75 vs. 65 %). Patients receiving the higher dose also experienced more dose-limiting neurotoxicity (45 vs. 23 %), large-volume diarrhea (15 vs. 0 %), and hepatotoxicity (7 vs. 0 %). There was no in-hospital mortality during treatment in either group. The average length of stay was similar between both groups (5 days, SD = 1 for both groups), and the median cumulative IL-2 exposure was similar between both groups for the first course (10.1 vs.10.5 million units/kg) and for all courses (approximately 11-12 million units/kg). Both high-dose IL-2 protocols had comparable in-hospital mortality and cumulative IL-2 exposure. The 720,000 units/kg/dose dosing scheme did not shorten the length of stay but did lead to greater acute toxicity. Therefore, as a result, we recommend 600,000 units/kg/dose when deciding between the two regimens.