Data from Phase 3 MORPHO trial selected for press briefing and to be presented as oral session during the 2023 European Hematology Association (EHA) Hybrid Congress

Exploratory results demonstrated improvement of relapse-free survival (RFS) in a subgroup of patients with measurable residual disease (MRD)

TOKYO and ROCKVILLE, Md., June 9, 2023 – Astellas Pharma Inc. (TSE: 4503, President and CEO: Naoki Okamura, “Astellas”) and the Blood and Marrow Transplant Clinical Trials Network (BMT CTN) today presented data from the Phase 3 MORPHO clinical trial which demonstrated favorable results in subgroups of FMS-like tyrosine kinase 3 (FLT3)-internal tandem duplication (ITD) mutated acute myeloid leukemia (AML) patients, including a subgroup of patients with detectable measurable residual disease (MRD). The data were shared during the 2023 European Hematology Association (EHA) Hybrid Congress Press Briefing, taking place in Frankfurt, Germany, and will also be presented as an oral session on June 11.

These data from the Phase 3 MORPHO trial, which evaluated gilteritinib as a maintenance therapy following allogeneic hematopoietic stem cell transplantation (HSCT) for patients with FLT3-ITD AML, did not demonstrate statistically significant improvement of relapse-free survival (RFS) in the entire cohort (Hazard Ratio [HR] for gilteritinib versus placebo 0.68; P=0.0518). However, there was clinical improvement of RFS in a subgroup of patients with detectable MRD (gilteritinib [72.4%] vs placebo [57.4%] at 2 years with HR: 0.515; 95% Confidence Interval [CI], 0.316-0.838; nominal P=0.0065) compared to patients without detectable MRD (HR: 1.213; 95% CI, 0.616-2.387; nominal P=0.575). In exploratory analysis, gilteritinib showed favorable RFS for the approximate 50% of patients with detectable MRD pre- or post-HSCT, compared to those without detectable MRD. In addition, RFS in the North American sub-population showed a HR of 0.397 (P=0.0022) for gilteritinib versus placebo. Further analysis is being conducted to understand regional results across the study population.

“While we are continuing to conduct a thorough assessment of the full data set from our Phase 3 MORPHO trial, we are encouraged by these data which explore the potential of gilteritinib in a maintenance setting,” said Ahsan Arozullah, M.D., M.P.H., Senior Vice President and Head of Oncology Development, Astellas. “AML patients with a FLT3-ITD mutation often face worse outcomes than those with other mutations and have restricted post-HSCT treatment options with unmet need. With these findings, we remain focused on sharing updates with the scientific community to inform continued innovation for the AML community.”

"As the AML treatment landscape continues to evolve, the exploration of prognostic indicators like MRD, which may be used to guide the management of AML, is vital to advance science and patient care,” said Mary M. Horowitz, M.D., Principal Investigator of the BMT CTN Data and Coordinating Center. “We look forward to continuing our collaboration with Astellas to explore innovative approaches for those impacted by AML.”

The Phase 3 MORPHO trial is a randomized, double-blind, placebo-controlled, multi-center trial that compares gilteritinib to placebo as maintenance therapy over a period of two years following HSCT in 356 patients with FLT3-ITD mutated AML and in remission after induction therapy. The study did not meet its pre-defined primary endpoint of RFS and key secondary endpoint of overall survival or patients treated with gilteritinib compared to placebo. The most frequent treatment-emergent adverse events (TEAEs) were decrease in neutrophil count, diarrhea and nausea, which were generally consistent with previous studies of gilteritinib. In FLT3-ITD AML patients, TEAEs associated with gilteritinib compared to placebo were neutrophil decrease (42.1% versus 15.8%) and increased incidence of chronic graft-versus-host disease (GVHD) (52.2% versus 42.1%). Additional data and sub-analyses will be submitted for publication and for consideration at upcoming medical meetings.

Gilteritinib is a FLT3 inhibitor with demonstrated activity against FLT3-ITD, a common driver mutation that presents with a high disease burden and poor prognosis, and FLT3-tyrosine kinase domain (TKD) mutations. Gilteritinib is available as XOSPATA® in the U.S., Japan, China and selected European countries for the treatment of adult patients who have relapsed or refractory FLT3+ AML.


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