MYLOTARG is currently FDA indicated for the treatment of patients with CD33-positive AML in first relapse who are 60 years of age or older and who are not considered candidates for other cytotoxic chemotherapy. CD 33+ is not required by the FDA.
There are a number of phase II studies showing effectiveness at various ages. The overall response rate (OR) for the 277 adult patients with AML (mean age: 58 years) in first relapse treated in phase 2 pivotal studies was 26% with 13% complete remission (CR) and 13% CRp (complete remission with incomplete platelet recovery). However, it is not clear that adding myelotarg to previously effective chemotherapy in a patient with a long relapse free interval is beneficial. Repeating the intially successful chemo, with a stem cell transplant consolidation is the standard approach to this situation, especially in younger patients. The only controlled studies are a single agent, in older patients, and not in combination with chemotherapy.
NCCN recommends single agent gemtuzumab in patients over age 60 and chemo with transplant or trials in younger patients.
A-L Taksin et al, High efficacy and safety profile of fractionated doses of Mylotarg as induction therapy in patients with relapsed acute myeloblastic leukemia: a prospective study of the alfa group
Leukemia (2007) 21, 66–71