Improvement of Remission Duration with Low-Dose Post-Remissional Gemtuzumab Ozogamicin (GO) in Elderly Patients with Acute Myeloid Leukemia

The prognosis for elderly patients with acute myeloid leukaemia (AML) is dismal. Intensive chemotherapy is offered only to fit patients. The complete remission is obtained usually in 50% of the patients. The remission duration is short and the majority of patients will relapse within one year, with a poor quality of life. In this study we have evaluated the outcome of sixty-eight elderly patients (mean age 69.2 years) with AML or high-risk myelodysplasia (HR-MDS) treated with an induction program with fludarabine (30 mg/sqm/day for 4 days), cytarabine (1 gr/sqm/day for 4 days) and interspaced continuous infusion of idarubicin (12 mg/sqm/day on days 1,3,5), followed by lenograstim (FLAIG). Thirty-six patients (53%) were in CR after the first course. Thirty-four received a second reduced outpatient course. To account for the “guarantee time” required to survive the induction and retain the CR until the beginning of the post-remissional treatment, we used a landmark analysis at three months from CR to evaluate the disease-free survival (DFS), therefore excluding from the analysis early relapses and deaths in CR. In the first cohort, 13 patients received a post-remissional treatment with thioguanine and weekly cytarabine until relapse. In the second cohort, 14 patients received gemtuzumab ozogamicin (GO) at 3 mg/sqm every 3 months for 1 year or until relapse. The two cohorts were comparable for age, WHO classification, karyotype and CD33 expression. No difference in the median overall survival (OS) was observed between the two cohorts (7.4 vs. 12.3 months; p=0.1).. The landmark analysis showed an improvement of the DFS in patients receiving a post-remissional treatment with GO in confront to those treated with maintenance chemotherapy. (12.5 vs. 6.73 months; p=0.04). Although not influencing survival, the prolongation of DFS without hospitalisation or complications may improve the quality of life of elderly AML patients. The post-remissional therapy with low-dose GO deserves further evaluation in prospective randomized studies.