A Study of ASP2215 (Gilteritinib) by Itself, ASP2215 Combined With Azacitidine or Azacitidine by Itself to Treat Adult Patients Who Have Recently Been Diagnosed With Acute Myeloid Leukemia With a FLT3 Gene Mutation and Who Cannot Receive Standard Chemotherapy

Event-free Survival (EFS)

EFS: time from the date of randomization until the date of documented relapse from Complete Remission (CR), treatment failure(failing to achieve CR within 6 cycles of treatment) or death from any cause, whichever occurred first. CR: bone marrow(BM) regenerating normal hematopoietic cells, morphologically leukemia-free state, absolute neutrophil count (ANC) ≥1 × 10\^9/L, platelet count ≥100 × 10\^9/L, normal marrow differential with \<5% myeloblast counts, missing/≤2% peripheral blood blast counts and being red blood cell (RBC) and platelet transfusion independent (1 week without RBC and platelet transfusion prior to the disease assessment). No evidence of extramedullary leukemia and Auer rods. Relapse: reappearance of leukemic blasts \>2% in the peripheral blood/≥ 5% myeloblasts in the BM unattributable to any other cause/new/reappearance of extramedullary leukemia.

Time frame: From the date of randomization until the date of documented relapse from CR, treatment failure or death from any cause, whichever occurred first (up to 39.7 months)

Percentage of Participants With Best Response

Best response for a participant was defined as the best measured response (in the order of CR, CR with Incomplete Platelet Recovery (CRp), CR with Incomplete Hematologic Recovery (CRi), and treatment failure) from all post-baseline visits. CR: BM regenerating normal hematopoietic cells, morphologically leukemia-free state, ANC ≥1 × 10\^9/L, platelet count ≥100 × 10\^9/L, normal marrow differential with \<5% myeloblast counts, missing/≤2% peripheral blood blast counts and being RBC and platelet transfusion independent (1 week without RBC and platelet transfusion prior to the disease assessment). No evidence of extramedullary leukemia and Auer rods. CRp: achieved CR except incomplete platelet recovery (\< 100 × 10\^9/L). CRi: achieved CR except incomplete hematological recovery with residual neutropenia \< 1 x 10\^9/L with or without complete platelet recovery. RBC and platelet transfusion independence not required.

Time frame: From the date of randomization until the date of death from any cause (up to 57 months)

Completed Remission (CR) Rate

CR rate: number of participants who achieved the best response of CR divided by the number of participants in the analysis population. Participants with unknown or missing response, or who provided no information on response at the end of treatment were included in the denominator when calculating rates. CR: BM regenerating normal hematopoietic cells, morphologically leukemia-free state, ANC ≥1 × 10\^9/L, platelet count ≥100 × 10\^9/L, normal marrow differential with \<5% myeloblast counts, missing/≤2% peripheral blood blast counts and being RBC and platelet transfusion independent(1 week without RBC and platelet transfusion prior to the disease assessment). No evidence of extramedullary leukemia and Auer rods.

Time frame: From the date of randomization until the date of death from any cause (approximately 49.7 months)

CRc Rate

CRc rate was defined as participants with best response of (CR + CRp + CRi) divided by the number of participants in the analysis population. Participants were classified as: CR: BM regenerating normal hematopoietic cells, morphologically leukemia-free state, ANC ≥1 × 10\^9/L, platelet count ≥100 × 10\^9/L, normal marrow differential with \<5% myeloblast counts, missing/≤2% peripheral blood blast counts and being RBC and platelet transfusion independent (1 week without RBC and platelet transfusion prior to the disease assessment). No evidence of extramedullary leukemia and Auer rods. CRp: achieved CR except incomplete platelet recovery (\< 100 × 10\^9/L). CRi: achieved CR except incomplete hematological recovery with residual neutropenia \< 1 x 10\^9/L with or without complete platelet recovery. RBC and platelet transfusion independence not required. Percentage of participants with CRc was reported.

Time frame: From the date of randomization until the date of death from any cause (approximately 54.5 months)

Complete Remission With Partial Hematologic Recovery (CRh)

CRh was defined as the response at a post baseline visit as CRh having bone marrow myeloblast count \< 5%, partial hematologic recovery ANC ≥ 0.5 x 10\^9/L and platelets ≥ 50 x 10\^9/L, no evidence of extramedullary leukemia and cannot be classified as CR. The blast counts in peripheral blood must be ≤ 2% or missing. CR: BM regenerating normal hematopoietic cells, morphologically leukemia-free state, ANC ≥1 × 10\^9/L, platelet count ≥100 × 10\^9/L, normal marrow differential with \<5% myeloblast counts, missing/≤2% peripheral blood blast counts and being RBC and platelet transfusion independent (1 week without RBC and platelet transfusion prior to the disease assessment). No evidence of extramedullary leukemia and Auer rods. Percentage of participants with CRh was reported.

Time frame: From the date of randomization until the date of death from any cause (up to 49.7 months)

CR/CRh Rate

CR/CRh rate: number of participants who achieved CR or CRh divided by the number of participants in the analysis population. CR/CRh: CR/CRh if it fulfilled criteria for CR or CRh at the visit. CR: BM regenerating normal hematopoietic cells, morphologically leukemia-free state, ANC ≥1 × 10\^9/L, platelet count ≥100 × 10\^9/L, normal marrow differential with \<5% myeloblast counts, missing/≤2% peripheral blood blast counts and being RBC and platelet transfusion independent (1 week without RBC and platelet transfusion prior to the disease assessment). No evidence of extramedullary leukemia and Auer rods. CRh: response at a post baseline visit as CRh having bone marrow myeloblast count \< 5%, partial hematologic recovery ANC ≥ 0.5 x 10\^9/L and platelets ≥ 50 x 10\^9/L, no evidence of extramedullary leukemia and cannot be classified as CR. The blast counts in peripheral blood must be ≤ 2% or missing. Percentage of participants with CR/CRh was reported.

Time frame: From the date of randomization until the date of death from any cause (up to 49.7 months)

Percentage of Participants With Transfusion Conversion Rate

Transfusion conversion rate was defined as the number of participants who were transfusion dependent at baseline period but became transfusion independent at post-baseline period divided by the total number of participants who were transfusion dependent at baseline period.

Time frame: From baseline up to 57 months

Percentage of Participants With Transfusion Maintenance Rate

Transfusion maintenance rate was defined as the number of participants who were transfusion independent at baseline period and remained transfusion independent post-baseline period divided by the total number of participants who were transfusion independent at baseline period.

Time frame: From baseline up to 57 months

Leukemia-free Survival (LFS)

LFS: time from the date of first CRc (CR + CRp + CRi) until the date of documented relapse (excluding relapse from PR) or death for participants who achieved CRc. CR: BM regenerating normal hematopoietic cells, morphologically leukemia-free state, ANC ≥1 × 10\^9/L, platelet count ≥100 × 10\^9/L, normal marrow differential with \<5% myeloblast counts, missing/≤2% peripheral blood blast counts and being RBC and platelet transfusion independent (1 week without RBC and platelet transfusion prior to the disease assessment). No evidence of extramedullary leukemia and Auer rods. CRp: achieved CR except incomplete platelet recovery (\< 100 × 10\^9/L). CRi: achieved CR except incomplete hematological recovery with residual neutropenia \< 1 x 10\^9/L with or without complete platelet recovery. RBC and platelet transfusion independence not required. CRc: fulfilled criteria for CR, CRp or CRi. Based on KM estimates.

Time frame: From first day of achieving first CRc to the first day of confirmed relapse/death (up to 54.5 months)

Duration of Remission

Duration of remission included CRc, CR, CRh, CR/CRh, and response duration \[CRc + PR\]. Duration of CRc, CR, CRh: the time from the date of first CRc until the date of first documented relapse for participants who achieved CRc, CR, and CRh, respectively. CR/CRh: fulfilled criteria for CR or CRh at the visit. CRh: marrow blasts \<5%, ANC ≥0.5×10\^9/L, platelets ≥50×10\^9/L, not meeting CR criteria. PR: If marrow myeloblasts between \<5% and 25% and ≤2% or missing peripheral blood blast and a decrease from baseline of at least 50% in the marrow myeloblasts and no evidence of extramedullary leukemia, the response was classified as PR. If marrow myeloblasts \<5% and ≤2% or missing peripheral blood blast and no evidence of extramedullary leukemia, the response was classified as PR even with Auer rods.

Time frame: From first day of achieving first response to the first day of confirmed relapse/death (up to 56.4 months)

Change From Baseline in Brief Fatigue Inventory (BFI)

The BFI was a tool to assess fatigue severity and impact on daily function in cancer participants over 24 hours. It included 9 items. A global fatigue score was computed by averaging the scores of the 9 items measured on the numeric rating scale. Scores were calculated if ≥5 of 9 items were answered. A higher score indicates a higher degree of fatigue. The first 3 rate fatigue from 0 (no fatigue) to 10 (worst imaginable), with higher scores indicating worse outcomes. The remaining 6 assess how fatigue interferes with daily activities from 0 (no interference) to 10 (completely interferes). A global fatigue score (0-10) was the average of all items, with higher scores indicating worse fatigue. Overall BFI score is reported.

Time frame: From baseline to 31 months

Number of Participants With Treatment Emergent Adverse Events (TEAEs)

An AE was defined as any untoward medical occurrence in a participant, temporally associated with the use of a medicinal product, whether or not considered related to the medicinal product. An AE could therefore be any unfavorable \& unintended sign (including an abnormal laboratory finding), symptom, or disease (new or exacerbated) temporally associated with the use of a medicinal product. TEAE was defined as an adverse event observed after starting administration of the study drug until 30 days from the last study treatment

Time frame: From first dose up to end of study duration (101 months)

Number of Participants With Eastern Cooperative Oncology Group (ECOG) Performance Scores

ECOG performance scores at each assessment time were be provided by treatment group. Negative change scores indicated an improvement and positive scores indicate a decline in performance. The grades were defined as follows: 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.

Time frame: From baseline to end of treatment (up to 57 months)