De novo AML patients with favourable–intermediate karyotype may benefit from the addition of low-dose gemtuzumab ozogamicin (GO) to fludarabine, Ara-C and idarubicin (FLAI): a contribution to the reopened “GO question”

We report the final results of a prospective trial testing the combination of fludarabine, Ara-C and idarubicin (FLAI) followed by low-dose gemtuzumab ozogamicin (FLAI-GO) in 85 patients aged 60 years or more with CD33+ acute myeloid leukaemia (AML). Median age was 68 years (60–82); karyotype was unfavourable in 21 patients (24 %), intermediate in 63 (74 %) and favourable in 1 (2 %). There were five therapy-related deaths. Of the 80 evaluable patients, 47 achieved complete response (CR) (58 %); CR rates were 65 and 32 % in good-intermediate/poor karyotype patients, respectively. Median length of CR was 7 months (3–76). The cumulative incidence of relapse was 84 % with an actuarial survival of 50.3 % at 1 year and 14.4 % at 2 years. The study control population is an unselected consecutive historic cohort of 104 patients treated with the FLAI regimen, who were matched for age and prognostic factors. CR rates after FLAI-GO and FLAI were comparable. However, patients with de novo AML and intermediate–favourable karyotype receiving GO had a significantly lower risk of relapse at 2 years as compared to patients not receiving GO (n = 77) (40 vs 80 %, p = 0.01) and significantly better disease-free survival (p = 0.018) and overall survival (p = 0.022).