Trial to Assess the Efficacy of Midostaurin (PKC412) in Patients With c-KIT or FLT3-ITD Mutated t(8;21) AML

AML patients displaying t(8;21) have a relatively favourable outcome. Nevertheless, only approximately 50% of patients carrying this cytogenetic aberration are alive at 5 years. This suggests that some patients have more aggressive leukemic phenotypes and indicates the need for treatment optimization with novel therapies.

The mutated KIT gene as well as the FLT3-ITD mutation have recently been identified as factors most likely to explain the heterogeneous clinical outcomes within the group of t(8;21) AML. The FLT3 and c-KIT genes encode type III receptor tyrosine kinases (RTK) with important and partly redundant functions in early hematopoietic stem cells. Various activating mutations have been described for both genes. For c-KIT, the incidence ranges from 17 to 48% depending on the source population and type of mutations determined. It has been consistently shown that in AMLs with t(8;21), mutated c-KIT is associated with a dramatically increased risk of relapse and reduced overall survival compared to their unmutated counterparts. The FLT3-ITD mutation has a similar negative effect on prognosis in the patient group of t(8;21) mutated AMLs as c-KIT.

PKC412 (midostaurin) is known to inhibit the c-KIT RTK activity as well as the FLT3 kinase, both in patients with ITD and TKD mutations. It should therefore be possible to abrogate the negative impact of pathologically increased c-KIT or FLT3-ITD activity on relapse and overall survival by using midostaurin in this patient population. Aim of the proposed clinical trial is to prove the efficacy of midostaurin in c-KIT or FLT3-ITD mutated t(8;21)- AMLs in an open-label one-arm design.

Inclusion criteria

• Diagnosis of c-KIT mutated t(8;21) AML i.e.

• >20% myeloid blasts in bone marrow and/or peripheral blood at initial diagnosis
• Plus cytogenetic diagnosis of aberration t(8;21)/AML1-ETO
• Plus mutation of c-KIT gene (mut-KIT17 or mut-KIT8) or FLT3-ITD mutation or both c-KIT and FLT3-ITD mutations
• Chemoresponsive disease as determined by early bone marrow assessment on day 14-16 after first cycle of induction therapy with cytarabine in combination with daunorubicine or idarubicine, or mitoxantrone- Fit for further intensive chemotherapy
• Age 18-65 years
• ECOG performance status of 0-2
• Life expectancy of at least 12 weeks

Exclusion criteria

• Primary refractory or previously relapsed AML
• Non-eligibility for high-dose cytarabine based consolidation, e.g. intolerance to cytarabine
• Inability to swallow oral medications
• Symptomatic congestive heart failure
• Bilirubin >2.5 x upper limit of normal