A Study of ASP2215 (Gilteritinib), Administered as Maintenance Therapy Following Induction/Consolidation Therapy for Subjects With FMS-like Tyrosine Kinase 3 (FLT3/ITD) Acute Myeloid Leukemia (AML) in First Complete Remission

RFS was defined as the time from the date of randomization until the date of documented relapse or death from any cause, whichever occurred first. Relapse after complete remission (CR) \[including complete remission with incomplete platelet recovery (CRp) and Complete remission with incomplete hematologic recovery (CRi)\], was defined as bone marrow blasts 5% or higher (not attributable to regenerating bone marrow), any circulating blasts, any extra-medullary blast foci as per Revised International Working Group (IWG) criteria. Participants were classified as: CRi, if they fulfilled all the criteria for CR except for incomplete hematological recovery with residual neutropenia \< 1 × 10\^9/L with or without complete platelet recovery. RBC and platelet transfusion independence was not required. CRp, if they achieved CR except for incomplete platelet recovery (\< 100 × 10\^9/L). RFS was estimated using Kaplan-Meier estimates. hazard ratio (HR), cox proportional hazards model (CHM)

Time frame: From the date of randomization until the date of documented relapse, or death; (Median time on study drug was 427 days for gilteritinib group and 212 days for placebo group)

Population: The full analysis set (FAS) consisted of all participants who were randomized.

MRD was measured from bone marrow samples. FLT3/ITD mutation ratio was measured in relation to total FLT3. For a participant with multiple ITD mutations, the overall FLT3/ITD mutation ratio was calculated from the sum of all ITD mutations. Absence of Minimal Residual Disease (MRD) is defined as log10-transformed overall FLT3/ITD mutation ratio ≤ -4.

Time frame: Baseline and months 3, 6, 12, 24/EoT

Population: FAS population with available data at specified time point.

EFS was defined as the time from the date of randomization until the date of documented relapse or discontinuation of the treatment, or initiation of other anti-leukemic treatment or death from any cause, whichever occurred first. Relapse after CR (including CRp and CRi), was defined as bone marrow blasts 5% or higher (not attributable to regenerating bone marrow), any circulating blasts, any extra-medullary blast foci as per Revised IWG criteria. Participants were classified as: CRi, if they fulfilled all the criteria for CR except for incomplete hematological recovery with residual neutropenia \< 1 × 10\^9/L with or without complete platelet recovery. RBC and platelet transfusion independence was not required. CRp, if they achieved CR except for incomplete platelet recovery (\< 100 × 10\^9/L). EFS was estimated using Kaplan-Meier's method.

Time frame: From date of randomization until the date of documented relapse or discontinuation of the treatment, or initiation of other anti-leukemic treatment or death from any cause; (Median time on study drug was 427 days for gilteritinib and 212 days for Placebo)

Population: FAS Population

An AE is any untoward medical occurrence in a participant administered a study drug, which does not necessarily have to have a causal relationship with treatment. It can, be any unfavorable and unintended sign, symptom or disease (new or exacerbated) temporally associated with the use of a medicinal product whether considered related to the medicinal product. An AE is considered serious if, it results in results in death, is life-threatening (an AE is considered life-threatening if, its occurrence places the participant at immediate risk of death, results in persistent or significant disability/incapacity or substantial disruption of the ability to conduct normal life functions, results in congenital anomaly or birth defect, Requires inpatient hospitalization (except for planned procedures as allowed per study) or leads to prolongation of hospitalization. TEAE was defined as an AE observed after starting administration of the study drug through 30 days after the last dose.

Time frame: From first dose date up to 30 days after last dose or data cut-off date 25-May 2021 (Maximum treatment duration was 744 days)

Population: The safety analysis set (SAF) consisted of all randomized participants who received at least one dose of study drug.

ECOG performance status was measured on an 6 point scale. 0-Fully active, able to carry on all pre-disease performance without restriction. 1. Restricted in physically strenuous activity but ambulatory and able to carry out work of a light or sedentary nature, e.g., light house work, office work. 2. Ambulatory and capable of all self-care but unable to carry out any work activities. Up and about more than 50% of waking hours. 3. Capable of only limited self-care, confined to bed or chair more than 50% of waking hours. 4. Completely disabled. Cannot carry on any self-care. Totally confined to bed or chair. 5. Dead. Number of participants with ECOG PS was reported. ECOG PS grades with zero participants were not reported.

Time frame: Months 1, 2, 3, 4, 5, 6, 8, 10. 12, 14, 16, 18, 20, 22 and 24/EoT

Population: Safety population with available data at specified time point.

OS was defined as the time from the date of randomization until the date of death from any cause. OS was estimated using Kaplan-Meiers method.

Time frame: From the date of randomization until the date of death from any cause; (Median time on study drug was 427 days for gilteritinib group and 212 days for placebo group)

Population: FAS Population