Defining the dose of gemtuzumab ozogamicin in combination with induction chemotherapy in acute myeloid leukemia: a comparison of 3 mg/m2 with 6 mg/m2 in the NCRI AML17 Trial.
Burnett A., Cavenagh J., Russell N., Hills R., Kell J., Jones G., Nielsen OJ., Khwaja A., Thomas I., Clark R., UK NCRI AML Study Group None.
Arecent source data meta-analysis of randomized trials in adults assessing the immunoconjugate gemtuzumab ozogamicin combined with standard chemotherapy in acute myeloid leukemia showed a significant survival benefit in patients without an adverse karyotype. It is not clear whether the optimal dose should be 3 mg/m(2) or 6 mg/m(2) In this study, we randomized 788 patients to a single dose of gemtuzumab ozogamicin 3 mg/m(2) or 6 mg/m(2) with the first course of induction therapy. We found that the rate of complete remission was higher with 3 mg/m(2) [82% vs 76%; odds ratio 1.46 (1.04-2.06); P=0.03], but this was balanced by a higher rate of complete remission with incomplete peripheral blood count recovery in the 6 mg/m(2) treatment (10% vs 7%) resulting in similar overall response rate [89% vs 86%; hazard ratio 1.34 (0.88-2.04); P=0.17]. There was no overall difference in relapse or survival at four years between the arms: 46% vs 54%; hazard ratio 1.17 (0.94-1.45), P=0.5, and 50% versus 47%; hazard ratio 1.10 (0.90-1.34), P=0.3, respectively. The 30- and 60-day mortality was significantly higher in the 6 mg/m(2) recipients: 7% versus 3%; hazard ratio 2.07 (1.11-3.87), P=0.02, and 9% versus 5%; hazard ratio 1.99 (1.17-3.39), P=0.01, respectively, which in addition was associated with a higher rate of veno-occlusive disease (5.6% vs 0.5%; P<0.0001). Our conclusion from this trial is that there is no advantage in using a single dose of 6 mg/m(2) of gemtuzumab ozogamicin in combination with induction chemotherapy when compared with a 3 mg/m(2) dose, with respect to response, disease-free and overall survival, either overall, or in any disease subgroup. (AML17 was registered as ISRCTN55675535).