Interleukin-2 for the treatment of advanced acute myelogenous leukemia patients with limited disease: updated experience with 20 cases.

Since 1988 we have treated a first group of 14 patients with recombinant interleukin-2 (rIL-2), which was previously published, and 6 other consecutive patients affected by refractory or relapsed acute myelogenous leukemia (AML) with >5% and < or = 30% bone marrow blasts, but not suitable for further chemotherapy. The rIL-2 schedule consisted of four 5-day high-dose cycles administered by continuous infusion with a 72-hour rest period between each cycle. Patients who achieved a response received a lower dose of subcutaneous rIL-2 maintenance treatment administered for 5 days every month. Following high-dose rIL-2, 11/20 patients (55%) obtained a complete remission (CR). Six remain in persistent CR after a median follow-up time of 50 months (9, 33, 49, 51, 52, 87 months, respectively); the length of remission is the longest in the natural history of the disease for each individual patient. One patient with stable disease at the end of rIL-2 induction is alive and well, with a stable number of blasts in the bone marrow, 18 months later. These 7 patients continue maintenance treatment with subcutaneous rIL-2. Close clinical and laboratory monitoring reveal that side effects are acceptable and no toxic deaths have been recorded. This update confirms the feasibility and antileukemic activity of high dose rIL-2 in advanced AML patients with limited disease, and suggests a potential clinical role of prolonged rIL-2 maintenance treatment.