Randomized trial of two schedules of low-dose gemtuzumab ozogamicin as induction mono- therapy for newly diagnosed acute myeloid leukaemia in older patients not considered candi- dates for intensive chemotherapy. A phase II study on the EORTC and GIMEMA leukaemia groups (AML-19)

This study compared two schedules of low-dose gemtuzumab ozogamicin(GO) as induction monotherapy for untreated acute myeloid leukaemia inolder patients unfit for intensive chemotherapy, to identify the morepromising regimen for further study. Patients were randomized to receiveeither best supportive care or a course of GO according to one of twoschedules: 3 mg/m2 on days 1, 3 and 5 (arm A), or GO 6 mg/m2 on day 1 and3 mg/m2 on day 8 (arm B). Primary endpoint was the rate of disease nonprogression(DnP), defined as the proportion of patients either achieving aresponse or maintaining a stable disease following GO induction in each arm.Fifty-six patients were randomized in the two GO arms (A, n = 29; B,n = 27). The rate of DnP was 38% [90% confidence interval (CI), 23–55] inarm A, and 63% (90% CI, 45–78) in arm B. Peripheral cytopenias were themost common adverse events for both regimens. The all-cause early mortalityrate was 14% in arm A and 11% in arm B. The day 1 + 8 schedule, which wasassociated with the highest rate of DnP, met the statistical criteria to beselected as the preferred regimen for phase III comparison with bestsupportive care.