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 recombina nt interleukin-2 (rIL-2), which was previously published, and 6 other consecutive patients affected by refractory or relapsed acute myelogen ous leukemia (AML) with >5% and less than or equal to 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 in fusion with a 72-hour rest period between each cycle. Patients who ach ieved a response received a lower dose of subcutaneous rIL-2 maintenan ce treatment administered for 5 days every month. Following high-dose rIL-2, 11/20 patients (55%) obtained a complete remission (CR). Six re main in persistent CR after a median follow-up time of 50 months (9, 3 3, 49, 51, 52, 87 months, respectively); the length of remission is th e longest in the natural history of the disease for each individual pa tient. One patient with stable disease at the end of rIL-2 induction i s alive and well, with a stable number of blasts in the bone marrow, 1 8 months later. These 7 patients continue maintenance treatment with s ubcutaneous rIL-2. Close clinical and laboratory monitoring reveal tha t side effects are acceptable and no toxic deaths have been recorded. This update confirms the feasibility and anti-leukemic activity of hig h dose rIL-2 in advanced AML patients with limited disease, and sugges ts a potential clinical role of prolonged rIL-2 maintenance treatment.