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2736 Multicenter, Open-Label, 3-Arm Study of Gilteritinib, Gilteritinib Plus Azacitidine, or Azacitidine Alone in Newly Diagnosed FLT3 Mutated (FLT3mut+) Acute Myeloid Leukemia (AML) Patients Ineligible for Intensive Induction Chemotherapy: Findings from the Safety Cohort

Program: Oral and Poster Abstracts
Session: 616. Acute Myeloid Leukemia: Novel Therapy, excluding Transplantation: Poster II
Hematology Disease Topics & Pathways:
Diseases, Leukemia, AML, Therapies, Non-Biological, Myeloid Malignancies, pharmacology
Sunday, December 2, 2018, 6:00 PM-8:00 PM
Hall GH (San Diego Convention Center)

Jordi Esteve, MD, PhD1, Rik Schots2*, Teresa Bernal Del Castillo, MD, PhD3*, Je-Hwan Lee, MD, PhD4, Eunice S. Wang, MD5, Shira Dinner, MD6, Mark D. Minden, MD, PhD7, Olga Salamero, MD8*, Jorge Sierra, MD9, Goichi Yoshimoto, MD, PhD10*, Kamel Laribi, MD11*, Janusz Halka, MD12*, Pau Fernandez13*, Shufang Liu14*, Elizabeth Shima Rich, MD, PhD14 and Erkut Bahceci, MD14

1Hematology department, Hospital Clínic de Barcelona, Barcelona, Spain
2UZ-Brussel-VUB, Jette, Belgium
3Hospital Universitario Central de Asturias, Oviedo, Spain
4Asan Medical Center, Seoul, Korea, Republic of (South)
5Department of Medicine, Roswell Park Cancer Institute, Buffalo, NY
6Robert H. Lurie Comprehensive Cancer Center, Chicago, IL
7Princess Margaret Hospital, Toronto, Canada
8Hospital Vall D´Hebron, Barcelona, Spain
9Servicio de Hematología, Hospital de La Santa Creu i Sant Pau, Barcelona, Spain
10Kyushu University Hospital, Fukuoka, Japan
11Centre Hospitalier Du Mans, Le Mans, France
12Warmian-Masurian Cancer Center of The Ministry of the Interior and Administration’s Hospital, Warszawa, Poland
13Hospital Universitari i Politècnic La Fe, Valencia; CIBERONC, Instituto Carlos III, Madrid, Spain
14Astellas Pharma Global Development, Northbrook, IL

Background: Gilteritinib, a highly selective, potent FLT3/AXL inhibitor, showed antileukemic activity with favorable tolerability in a phase 1/2 trial of patients (pts) with FLT3mut+ relapsed/refractory AML (Perl AE, et al. Lancet Oncol. 2017). Gilteritinib plus azacitidine (AZA) synergistically induced apoptosis and inhibited growth in the MV4-11 cell line and in MV4-11 tumors (Ueno Y, et al. Blood. 2016). The safety, tolerability, and efficacy of gilteritinib alone, gilteritinib plus AZA, or AZA alone is being evaluated in pts with newly diagnosed FLT3mut+ AML ineligible for intensive induction chemotherapy; this abstract presents data from the Safety Cohort which evaluated only gilteritinib plus AZA.

Methods: Adults with newly diagnosed FLT3mut+ (FLT3-ITD or FLT3-TKD) AML are being enrolled in this ongoing clinical trial (NCT02752035). Prior to initiation of the randomized portion of the study, the appropriate gilteritinib dose for combination therapy was assessed in a Safety Cohort. Patients enrolled in this cohort received escalating doses of oral gilteritinib (80 or 120 mg/day) on Days 1–28 in combination with subcutaneous or intravenous AZA (75 mg/m2/day) on Days 1–7. Observations of dose-limiting toxicities (DLTs) were collected through Cycle 1; treatment was continued in 28-day cycles until lack of clinical benefit or unacceptable toxicity. Safety and tolerability were the primary endpoints of the Safety Cohort; antileukemic response rates (ie, complete remission [CR], CR with incomplete platelet recovery [CRp], CR with incomplete hematological recovery [CRi], partial remission [PR], and overall response rate [ORR]) were also assessed.

Results: A total of 15 adult pts (median age, 76 [range: 65–86]) were enrolled into the Safety Cohort (n=9, 80 mg gilteritinib; n=6, 120 mg gilteritinib); 14 pts were FLT3mut+ (ITD alone, n=10; TKD alone, n=3; ITD and TKD, n=1) and 1 pt had no FLT3 mutation. As of 25 June 2018, more than half (n=8/15; 56%, Figure) of the pts had a treatment duration of >6 mo, while 9 pts discontinued treatment (death, n=4; relapse; adverse event [AE]; physician decision; sponsor decision; subject withdrawal, n=1 each) and 6 pts remained on treatment. During the DLT observation period, 1 DLT (tumor lysis syndrome) was observed in a pt who received 80 mg gilteritinib plus AZA; no DLTs were reported in pts who received 120 mg gilteritinib plus AZA. One or more AEs were seen in all 15 pts; 12 (80%) experienced AEs considered at least possibly related to treatment. Adverse events occurring in ≥25% of pts were anemia (n=7), febrile neutropenia and nausea (n=6 each), increased ALT and AST, constipation, diarrhea, neutropenia, thrombocytopenia, and pyrexia (n=5 each), and decreased appetite, fatigue, increased blood creatinine, and hypocalcemia (n=4 each). Grade ≥3 AEs occurring in ≥25% of pts were febrile neutropenia (n=6), anemia and neutropenia (n=5 each), and thrombocytopenia (n=4). Serious AEs occurring in >2 pts were febrile neutropenia (n=5), and anemia and pyrexia (n=3 each). Of the 8 pts with fatal AEs, none of which were related to treatment, 3 occurred early in treatment: septic shock (Day 2), respiratory failure (Day 6), and cerebral hemorrhage in the setting of acute kidney injury and uremia (Day 17). None of the 13 pts with post-baseline lab data had any potentially clinically significant AST/ALT (>3 X ULN) and total bilirubin (>2 X ULN) values; none of the pts had a maximum post-baseline QTcF interval >500 msec.

Across the Safety Cohort, a composite complete remission rate of 67% (n=10/15) was observed; 4 pts achieved a best overall response of CR and 6 achieved CRi (Figure). Two additional pts (13%) achieved a best overall response of PR, giving an ORR of 80%.

One DLT from the 11 DLT evaluable pts (defined as pts who experienced a DLT, or in the absence of DLT, received at least 23 of 28 doses of gilteritinib and at least 5 of 7 doses of AZA during the DLT observation period) informed the decision to proceed to the randomized portion at a dose of 120 mg gilteritinib for the combination treatment arm.

Conclusions: Gilteritinib and AZA were generally well tolerated with no unexpected AEs. This combination therapy induced antileukemic responses in newly diagnosed FLT3mut+ AML pts unfit to receive standard induction chemotherapy. Based on these results, pts are being enrolled into the randomized portion of the study with a dose of 120 mg gilteritinib for the combination treatment arm.

Disclosures: Wang: Abbvie: Consultancy, Membership on an entity's Board of Directors or advisory committees; Pfizer: Consultancy, Membership on an entity's Board of Directors or advisory committees; Abbvie: Consultancy, Membership on an entity's Board of Directors or advisory committees; Amgen: Consultancy; Pfizer: Consultancy, Membership on an entity's Board of Directors or advisory committees; Novartis: Speakers Bureau; Novartis: Speakers Bureau; Jazz: Speakers Bureau; Jazz: Speakers Bureau; Amgen: Consultancy. Laribi: Amgen: Other: Personal fees; Takeda: Other: Grant and personal fees; Sandoz: Other: Grant; Novartis: Other: Grant and personal fees; Teva: Other: Grant; Gilead: Other: Personal fees; Hospira: Other: Grant; Roche: Other: Grant. Fernandez: Daiichi Sankyo: Consultancy, Speakers Bureau; Novartis: Research Funding, Speakers Bureau. Liu: Astellas Pharma: Employment. Rich: Astellas Pharma: Employment. Bahceci: Astellas Pharma: Employment.

*signifies non-member of ASH