NORTHBROOK, Ill., June 22, 2017 /PRNewswire/ -- Astellas today announced that investigational data from the Phase I/II CHRYSALIS trial studying anti-leukemic activity and tolerability of gilteritinib, a FLT3/AXL inhibitor, in patients with FLT3 mutation-positive relapsed or refractory (R/R) acute myeloid leukemia (AML) were published in The Lancet Oncology.

"Although AML is an uncommon blood cancer, approximately one third of patients have FLT3 tyrosine kinase mutations, which are associated with high relapse rates and poor survival.  Once relapsed, FLT3 mutated AML is extremely difficult to treat with current therapies and rarely curable. Targeting FLT3 in the clinic has long been a therapeutic goal, but historically this has proven challenging," said Alexander E. Perl, M.D., University of Pennsylvania-Abramson Comprehensive Cancer Center. "There is a need for new agents to treat relapsed FLT3 mutated disease and it is exciting that these data for gilteritinib have been published in Lancet Oncology," added Jessica K. Altman, M.D., Robert H. Laurie Cancer Center of Northwestern University.

Mutations of the FLT3 gene in AML, including internal tandem duplications (ITD), are present in approximately one third of AML patients. These mutations lead to constitutive activation of the tyrosine kinase receptor, thereby promoting proliferation and survival of leukemia cells and contributing to a higher relapse rate and a poor prognosis to treatment. FLT3 tyrosine kinase domain (FLT3-TKD) mutations and AXL receptor tyrosine kinase domain mutations have been associated with resistance to early generation FLT3 inhibitors.

The CHRYSALIS Study, an international, multicenter, open-label, Phase I/II dose-escalation/ dose-expansion study, involved a total of 252 adults with R/R AML, including 58 with wild-type FLT3 and 191 with FLT3 mutations (FLT3-ITD, n=162; FLT3-D835, n=16; FLT3-ITD and -D835, n=13), that received oral gilteritinib (20 – 450 mg) once daily in one of seven dose-escalation (n=23) or dose-expansion (n=229) cohorts. The primary objectives were to assess the safety and tolerability and pharmacokinetics of gilteritinib; with the secondary objectives assessing anti-leukemic activity and drug-drug interactions. 

The most common Grade 3/4 adverse events were febrile neutropenia (39%; n=98/252), anemia (24%; n=61/252), thrombocytopenia (13%; n=33/252), sepsis (11%; n=28/252), and pneumonia (11%; n=27/252). Gilteritinib demonstrated inhibition of FLT3 phosphorylation at doses >80 mg/d in correlative assays. While responses were observed across all dose levels, regardless of FLT3 mutation status (overall response rate (ORR)=40%), response rate was enhanced in FLT3 mutation-positive patients at doses ≥80 mg/d (ORR=52%). Among patients with FLT3-ITD, the additional presence of FLT3-D835 did not alter response rate; patients with only FLT3-D835 responded less frequently.

Astellas is further investigating the potential benefit of gilteritinib in various AML patient populations through several planned and already initiated trials, including the Phase 3 ADMIRAL study in R/R AML.

"AML is a disease that represents a high unmet clinical need and we continue to be encouraged by the results achieved thus far with gilteritinib," said Steven Benner, M.D., senior vice president and global therapeutic area head, oncology development, Astellas. "We look forward to further investigating this potential treatment in hopes of bringing new options to patients."

The safety and efficacy of the agent discussed herein are under investigation and have not been established. There is no guarantee that the agent will receive regulatory approval and become commercially available for the uses being investigated. Information about pharmaceutical products (including products currently in development) which is included in this press release is not intended to constitute an advertisement or medical advice.

About the CHRYSALIS Study

The CHRYSALIS Study is a Phase 1/2 study with objectives of determining the safety, tolerability, pharmacokinetic profile, and anti-leukemic activity of gilteritinib (ASP2215) in patients with R/R AML. Gilteritinib showed FLT3 inhibition at doses ≥80 mg/day. A 52% overall response rate (ORR) was demonstrated regardless of prior therapy. Additionally, a 55% ORR was observed in patients who had a FLT3-ITD and 37% ORR was observed in patients who were treated with a tyrosine kinase inhibitor prior to the study. Median OS in the full analysis set was approximately 25 weeks (95% CI: 20--30), and 31 weeks (95% CI: 24-59) in FLT3+ patients receiving ≥80mg of gilteritinib.  Commonly reported adverse events judged to be related to gilteritinib were typical of those associated with acute myeloid leukemia drugs: diarrhea, fatigue, elevated aspartate aminotransferase, and increased alanine aminotransferase. A maximum post-baseline QTcF interval prolongation longer than 500 ms. was reported in 4% of subjects.

About Astellas

Astellas is a pharmaceutical company dedicated to improving the health of people around the world through the provision of innovative and reliable pharmaceutical products. For more information on Astellas, please visit our website at www.astellas.us. You can also follow us on Twitter at @AstellasUS, Facebook at www.facebook.com/AstellasUS or LinkedIn at www.linkedin.com/company/astellas-pharma.

SOURCE Astellas