A phase II study of interleukin-2 in 49 patients with relapsed or refractory acute leukemia

In this report we present the results of a multicenter phase II study of hi gh-dose recombinant Interleukin-2 (rIL-2) in patients with refractory or re lapsed acute leukemia. Forty-nine patients with acute myeloid leukemia (AML : 30 patients) or acute lymphoblastic leukemia (ALL: 19 patients) were incl uded. Median age was 30 years (range: 4-71). Four patients were treated for primary refractory disease and 45 for relapsed disease (16 patients > 2(nd ) relapse). Twenty-four patients (49 %) had previously received bone marrow transplantation (allogeneic: 5, autologous: 19). Patients were scheduled t o receive three 5-day cycles of rIL-2 given every other week. rIL-2 was adm inistered as bolus LV. infusion of 8 x 10(6) UI/m(2)every 8 hours during cy cle I and every 12 hours during cycles 2 and 3. Patients received a mean of 76 % of rIL-2 planned dose. Main toxicity was h ematologic (grade IV thrombopenia: 84 %). Hemodynamic and metabolic toxicit ies lead to treatment discontinuation in 10 patients (20 %). Strong immune activation was achieved including a significant increase in activated T-cel ls and Lymphokine-Activating-Killer cell (LAK) activity. Twenty-seven out o f 30 AML patients could be evaluated for response: 2 (7 %) achieved complet e remission (CR) which lasted 3 and 4 months. No response was observed in t he 18 assessable ALL patients, most of whom (77 %) presented absolute drug resistance. These results show that this high dose rIL-2 regimen induces si gnificant biological effects and provides some anti-leukemic activity in pa tients with advanced leukemia Considering the severe toxicity observed and the Limited remission rate achieved here, rIL-2 does not appear to be a val uable therapeutic option for such patients. However, the undoubted anti-leu kemic activity of this cytokine invites further investigation especially in the minimal residual disease situation.