A phase I study of an outpatient regimen of recombinant human interleukin-2 and alpha-2a-interferon in patients with solid tumors

This study was undertaken to define the maximum tolerated dose (MTD) of recombinant interleukin-2 (IL-2) that could be combined with a fixed dose of alpha-2a-interferon (alpha-IFN) in an outpatient setting. The schedule called for IL-2 to be given by a 2-hour intravenous infusion 5 days a week for 4 weeks. The alpha-IFN was given at a dose of 6 x 10(6) U/m2/d intramuscularly 3 days per week (Monday, Wednesday, and Friday). The IL-2 dose was escalated in four dose levels from 1 to 4 x 10(6) U/m2/d. The MTD in this study of 17 patients was at the fourth dose level of IL-2 (4 x 10(6) U/m2/d). In addition to the usual IL-2 toxicities, debilitating fatigue limited outpatient administration of this dose. Although the response rate was low, with partial responses seen in only 1 of 15 patients, 2 of 5 patients with melanoma treated at the higher dose levels had objective tumor shrinkage with one partial and one minor response. Thus, an IL-2 dose of 3 x 10(6) U/m2/d combined with a recombinant alpha-2a-IFN dose of 6 x 10(6) U/m2/d is recommended for Phase II studies.