Phase II trial of hu14.18-IL2 for patients with metastatic melanoma

Abstract

Phase I testing of the hu14.18-IL2 immunocytokine in melanoma patients showed immune activation, reversible toxicities, and a maximal tolerated dose of 7.5 mg/m(2)/day. In this phase II study, 14 patients with measurable metastatic melanoma were scheduled to receive hu14.18-IL2 at 6 mg/m(2)/day as 4-h intravenous infusions on Days 1, 2, and 3 of each 28 day cycle. Patients with stable disease (SD) or regression following cycle 2 could receive two additional treatment cycles. The primary objective was to evaluate antitumor activity and response duration. Secondary objectives evaluated adverse events and immunologic activation. All patients received two cycles of treatment. One patient had a partial response (PR) [1 PR of 14 patients = response rate of 7.1 %; confidence interval, 0.2-33.9 %], and 4 patients had SD and received cycles 3 and 4. The PR and SD responses lasted 3-4 months. All toxicities were reversible and those resulting in dose reduction included grade 3 hypotension (2 patients) and grade 2 renal insufficiency with oliguria (1 patient). Patients had a peripheral blood lymphocytosis on Day 8 and increased C-reactive protein. While one PR in 14 patients met protocol criteria to proceed to stage 2 and enter 16 additional patients, we suspended stage 2 due to limited availability of hu14.18-IL2 at that time and the brief duration of PR and SD. We conclude that subsequent testing of hu14.18-IL2 should involve melanoma patients with minimal residual disease based on compelling preclinical data and the confirmed immune activation with some antitumor activity in this study.

Fig. 1

Antibody-dependent cell-mediated cytotoxicity (ADCC) with hu14.18-IL2 in patient serum. The M21 human melanoma target (% cytotoxicity; effector / target ratio of 50:1) was evaluated with (+) and without (−) effector PBMC from a healthy control donor in medium containing patient serum obtained pretreatment (pre) or after the initial 4 h hu14.18-IL2 infusion (4 h)

Fig. 2

Mean peripheral blood lymphocyte count (cell number per mcl ± SD) at the indicated protocol day for the 14 patients in this study. Time points are pretreatment (Pre) and at the indicated cycle (C) and day (D) of that cycle. Changes from Pre were significant for C1D3, C1D8, C2D3, C2D26 (p < 0.001), and C1D26 (p = 0.011)