Gemtuzumab-Ozogamicin as Post-Consolidation Therapy In Elderly Patients with Acute Myeloid Leukemia: a Pilot Study

Abstract 4357

The optimal post-remission treatment for elderly patients with acute myeloid leukemia (AML) is presently unknown.

We evaluated safety and efficacy of low dose Gemtuzumab-Ozogamicin (GO) as post-remission late consolidation therapy in a cohort of 19 consecutive patients, enrolled in a pilot prospective study. Between June 1999 and February 2010 we observed 152 elderly patients, aged more than 60 years and affected by AML. One hundred and two patients (67%) were considered fit for aggressive therapy and received intensive induction and consolidation therapy including HD Ara-C, Idarubicine and Amifostine. Thirty-nine patients (38%) were over 70 years, 38% had a secondary disease, 35% unfavourable, 45% intermediate and 4 % favourable prognosis Karyotype. Those achieving successful mobilization received autologous transplant while poor mobilizers received a second consolidation with three monthly courses of GO 3 mg/sm i.v. followed by three other courses of GO administered every 3 months.

Seventy-two patients achieved CR (69%) after induction: one patiente died in CR, 5 patients had a PS ≥2 and the remaining 66 were elegible for first consolidation. Fifty of these maintained the CR status and received a second consolidation: 19 with GO, 20 with Autologous transplant, and 6 with chemotherapy alone for patient decision. Five patients with a family donor received Allogeneic Transplant and were not included in this analysis.

GO was well tolerated: no major adverse events were seen. We overall observed 18 WHO grade III/IV adverse events were all transitory and included hematological toxicity (n = 17), hypertransaminasemia (n = 1).

Eight patients (42%) relapsed after GO consolidation and received a GO reinduction: five eventually died after a median follow-up of 13 months while three are still alive with a median follow up of 10 months. Five out of 20 patients died of transplant related toxicity (25%) and 9 relapsed (45%) after autologous transplant. All nine patients died of progressive disease. Five of the 6 patients receiving chemotherapy (83%) relapsed and died.

Five years Overall survival was 22% and Disease Free Survival 29.5% in the whole cohort of patients (median follow-up: 50 mouths). The landmark analysis showed a superior outcome in patients receiving GO with a 60% 5 yrs OS and DFS (median follow-up: 60 months) in comparison with patients receiving autologous transplant (28% 5 yrs OS and DFS with median follow-up 70 months) and chemotherapy (17% 5 yrs OS and DFS with a median follow-up of 77 months) (p= 0.009). In conclusion patients receiving GO had a better outcome in comparison with patients receiving autologous transplant and chemothearapy. High percentages of poor mobilizers and transplant related mortality seem to jeopardize autologous transplant feasibility and safety in elderly patients. GO showed to be an alternative and feasible choice in our series, with a low relapse rate, and a low toxicity profile.