TOKYO – December 3, 2018 – Astellas Pharma Inc. (TSE: 4503, President and CEO: Kenji Yasukawa, Ph.D. “Astellas”) today announced updated results from a Phase 1 study of gilteritinib in combination with induction and consolidation chemotherapy in patients newly diagnosed with FLT3 mutation-positive (FLT3mut+) Acute Myeloid Leukemia (AML). The data were presented today in an oral presentation (Abstract 564) at the 60th American Society of Hematology (ASH) Annual Meeting.

“A diagnosis of AML can be devastating for patients. It is a life-threatening disease and treatment usually needs to start as quickly as possible,” said Keith W. Pratz, M.D., of John Hopkins Sidney Kimmel Comprehensive Cancer Center, who presented the data at the ASH Annual Meeting. “Typical treatment for AML consists of induction and consolidation therapy. However, treatment options targeted for specific mutations may be important tools in physicians’ armamentarium of therapies for patients with AML. These results help advance our scientific understanding of how to potentially address these mutations in first-line treatment of AML.”

The purpose of this ongoing, open-label dose escalation/expansion Phase 1 clinical study (NCT02236013) is to assess the safety, tolerability and antitumor effects of gilteritinib when combined with induction and consolidation chemotherapy, and as single-agent maintenance therapy, in adult patients with newly diagnosed AML.1

The two-part trial first enrolled patients to successive cohorts to determine the Maximum Tolerated Dose. Patients in the dose expansion cohort received gilteritinib at the recommended expansion dose established during dose escalation.

As of October 11, 2018, 68 subjects had been enrolled in the study; 66 are included in the safety analysis set. Of these patients, 36 (54.5%) had FLT3 mutations (FLT3-ITD, n=26). During dose-escalation, two patients in the 40 mg/day cohort who had received gilteritinib on days 1-14 experienced dose-limiting toxicities (DLTs; neutropenia, thrombocytopenia, decreased ejection fraction). After the gilteritinib induction schedule change, no more DLTs occurred at this dose. Two patients in the 200 mg/day cohort experienced DLTs (neutropenia, neutropenic enterocolitis). The maximum tolerated dose and the recommended expansion dose were established at 120 mg/day.

Additional key findings include:

  • The end-of-treatment investigator-reported rate of composite complete remission (CRc) for response evaluable FLT3mut+ subjects receiving gilteritinib 120 mg on Schedule 1 (n=17) was 100%.
     
  • The CRc rate in FLT3mut+ subjects receiving Schedule 2 induction with idarubicin was 66.7%. 
     
  • Among subjects who received ≥80 mg/day gilteritinib (n=52), the CRc rate for FLT3mut+ subjects was 90.3% (n=28/31).
     
  • Median overall survival has not been reached. Median disease-free survival was 430 days (95% CI: 155, 630).
     
  • Grade ≥3 adverse events (AEs) in ≥10% of subjects were febrile neutropenia (63.6%), thrombocytopenia (19.7%), decreased platelet count (19.7%), decreased white blood cell count (19.7%), neutropenia (19.7%), decreased neutrophil count (16.7%), anemia (13.6%), and sepsis (10.6%).
     
  • Serious drug-related AEs in >1 subject were febrile neutropenia (n=11), sepsis (n=4), small intestinal obstruction, and decreased ejection fraction (both n=2).

Gilteritinib, under the brand name XOSPATA®, is approved by the U.S. Food and Drug Administration (FDA) for the treatment of adult patients who have relapsed or refractory AML with a FLT3 mutation as detected by an FDA-approved test.2 Gilteritinib is also approved by the Japan Ministry of Health, Labor and Welfare (MHLW) for relapsed or refractory AML with FLT3 mutations.