A Global Study of the Efficacy and Safety of Midostaurin + Chemotherapy in Newly Diagnosed Patients With FLT3 Mutation Negative (FLT3-MN) Acute Myeloid Leukemia (AML)

The purpose of this study was to confirm the preliminary evidence from early clinical trials that midostaurin may provide clinical benefit not only to AML patients with the FLT3-mutations but also in FLT3-MN (SR\<0.05) AML (FLT3 mutant to wild type signal ratio below the 0.05 clinical cut-off).

This study evaluated the efficacy and safety of midostaurin in combination with daunorubicin or idarubicin and cytarabine for induction and intermediate-dose cytarabine for consolidation, and midostaurin single agent post-consolidation therapy in newly diagnosed patients with FLT3-MN (SR\<0.05) AML.

This was a multi-center, multinational, randomized, double-blind Phase III study using a group sequential design. Subjects were stratified according to age (\<60 vs. ≥ 60 years). Subjects within each stratum were randomized in a 1:1 ratio into one of two treatment arms: Midostaurin + chemotherapy 'or' Placebo + chemotherapy.

The study consisted of the following phases:

Screening/randomization phase: Subjects had to sign informed consent form before screening for enrollment. Subjects started chemotherapy at day 1 and were randomized at day 8.

Induction phase: All subjects received at least one cycle (28 days) of induction therapy with continuous infusion cytarabine (D1 - D7) and daunorubicin or idarubicin (D1 - D3) (induction 1). Subjects who did not achieve CR or CRi with adequate blood count recovery after Induction 1 received a second cycle with intermediate-dose cytarabine (D1 - D3) and daunorubicin or idarubicin (D1 - D3) (induction 2). Subjects who did not achieve CR or CRi with adequate blood recovery after induction 2 discontinued study treatment and were followed for survival.

Consolidation phase: Subjects who achieved CR or CRi with adequate blood count recovery after induction with one or two cycles of induction proceeded to consolidation therapy with either 3 or 4 cycles respectively of intermediate-dose cytarabine (D1 - D3), or to Hematopoietic Stem Cells Transplantation (HSCT) with or without preceding consolidation cycles.

Post-consolidation phase: Subjects who maintained CR or CRi with adequate blood count recovery at the end of the consolidation phase received 12 cycles (28 days/cycle) of continuous therapy with midostaurin or placebo twice daily at 50 mg. Subjects who underwent HSCT after achieving CR or CRi with adequate blood count recovery received midostaurin or placebo twice daily 50 mg post-transplant therapy, continuously, for up to 12 cycles (28 days/cycle). Post HSCT post-consolidation therapy began \>30 days but not later than 100 days following HSCT.

Follow-up phase: All enrolled subjects were followed through the treatment period and until relapse/treatment failure, thereafter for start of new line of therapy and survival.

Eligibility Criteria:
Inclusion Criteria:

1. Diagnosis of AML (≥20% blasts in the bone marrow based on WHO 2016 classification). Patients with APL with PML-RARA are not eligible.
2. Suitability for intensive induction chemotherapy in the judgment of the investigator
3. Documented absence of an ITD and TKD activating mutation at codons D835 and I836 in the FLT3 gene, as determined by analysis in a Novartis designated laboratory using a validated clinical trial assay with clinical cutoff of 0.05 mutant to wild type signal ratio
4. Age ≥18 years
5. Laboratory values that indicate adequate organ function assessed locally at the screening visit

Exclusion Criteria:

1. Central nervous system (CNS) leukemia
2. Therapy-related secondary AML
3. Isolated extramedullary leukemia
4. Prior therapy for leukemia or myelodysplasia
5. AML after antecedent myelodysplasia (MDS) with prior cytotoxic treatment (e.g., azacytidine or decitabine)
6. Prior treatment with a FLT3 inhibitor (e.g., midostaurin, quizartinib, sorafenib)