Assessment of the toxicities of systemic low-dose interleukin-2 administered in conjunction with a melanoma peptide vaccine

In this phase 2 study, the authors assessed the hematologic and clinical toxicities of a melanoma peptide vaccine administered in conjunction with low-dose interleukin-2 (IL-2) therapy. Forty patients were randomized to receive a weekly vaccine paired with a regimen of subcutaneous IL-2 (3 x 10(6) IU/m(2)/day) administered daily for 6 weeks beginning either at week 1 or at week 4 of vaccine therapy. The differences in the time course of the IL-2 between the two groups permitted assessment of the cause of the toxicities, due either to IL-2 or to vaccine components. Both treatment regimens were well tolerated in the outpatient setting. Toxicities attributable to the vaccine components were principally limited to grade I injection site reactions. Systemic clinical toxicities correlated with the initiation of IL-2 therapy. These toxicities coincided temporally and in magnitude with changes in circulating eosinophil counts, suggesting that. systemic clinical toxicities and eosinophilia may have common etiologic pathways. Other minor toxicities attributable to this low-dose IL-2 regimen were clinically insignificant hepatic toxicity, mild anemia, and mild thrombocytosis. The hematologic effects of this therapy were delayed in time between the two treatment groups, without dramatic differences in magnitude, which suggests minimal modulation of the IL-2 toxicity by components of the vaccine.