High response rate for treatment with gemtuzumab ozogamicin and cytarabine in elderly patients with acute myeloid leukemia and favorable and intermediate-I cytogenetic risk

Abstract

Recent studies have reevaluated whether gemtuzumab ozogamicin (GO) improves the outcome of acute myeloid leukemia (AML) in elderly patients. Over 5 years, we treated 16 elderly patients with AML with GO and cytarabine. A high response rate, prolonged survival, and low toxicity were observed in the favorable and intermediate-I genetic groups of AML. Our study raises the issue about the optimal protocol for these patients.

Background: The benefit of gemtuzumab ozogamicin (GO) in combination with chemotherapy as frontline therapy in patients with acute myeloid leukemia (AML) is still debated.

Patients and methods: We evaluated the safety and efficacy of low-dose GO with cytarabine in elderly patients with newly diagnosed AML. Over the past 5 years, we have treated 16 elderly patients with AML (64-82 years) with GO (3 mg/m(2)) followed by continuous infusion of cytarabine (100 mg/m(2)) for 7 days.

Results: Complete remission (CR) was achieved in 68.8% of patients; however, this was true only in patients in the favorable or intermediate-I cytogenetic risk groups. Of the 12 patients with AML in the favorable and intermediate-I genetic groups, 11 (91.7%) achieved CR. By comparison, of all 4 patients in the intermediate-II or adverse genetic groups, none of the patients achieved CR (P = .003). The median disease-free survival and overall survival (OS) was 10.9 and 18.8 months, respectively, for patients who achieved CR. The estimated median survival was 15 months in the favorable and intermediate-I cytogenetic groups and only 4.4 months in the intermediate-II and unfavorable risk groups (P = .008). The toxicity profile was also manageable in patients with AML who were mainly older than 70 years with good performance status (PS). The 8-week mortality rate was 6.25%, which is relatively low in this high-risk group of patients. These data are in line with results from 2 randomized trials suggesting that the addition of low-dose GO should be further investigated to reevaluate its role in selected elderly patients with AML and raises the issue of the optimal protocol.