Ambit Biosciences presents data from Phase 2 ACE study of quizartinib for treatment of AML

Ambit Biosciences Corporation (Nasdaq: AMBI) announced today data from the Phase 2 ACE study of quizartinib (AC220), a FLT3 inhibitor, were featured in multiple presentations at the 18^th Congress of the European Hematology Association in Stockholm, Sweden.

Data presented included analyses of patients with relapsed or refractory acute myeloid leukemia (AML) from a Phase 2 clinical trial of quizartinib as monotherapy. In the study, quizartinib was administered orally, once a day, in 28-day treatment cycles until disease progression, elective hematopoietic stem cell transplantation (HSCT) or unacceptable toxicity. Based on the positive data from the Phase 2 clinical trial, as well as ongoing discussions with the Food and Drug Administration (FDA), Ambit is planning to initiate a Phase 3 clinical trial in FLT3-ITD positive patients with relapsed or refractory AML in early 2014.

Data Presentations

High Response Rate and Bridging to Hematopoietic Stem Cell Transplantation With Quizartinib (AC220) in Patients With FLT3-ITD– Positive Relapsed/Refractory Acute Myeloid Leukemia (AML)
Mark J. Levis, M.D., Ph.D., Department of Oncology, Johns Hopkins University School of Medicine, Baltimore, Md.

Data from 136 FLT3-ITD positive patients, aged 18 years or older, with either relapsed disease or who were refractory to second-line chemotherapy or HSCT, were presented. Of the patients treated, 35 percent were successfully bridged to a potentially curative HSCT, with the greatest proportion receiving a HSCT after achieving a CRi (complete remission with incomplete hematologic recovery) with quizartinib. Additionally, 33 percent of patients who were bridged to HCST after achieving a CRi were still alive after one year, with multiple patients alive after more than two years. 

Additional key findings presented include:

• Forty-six percent of FLT3-ITD positive patients achieved a composite complete response (CRc: complete remission (CR) + complete remission with incomplete platelet recovery (CRp) + complete remission with incomplete hematologic recovery (CRi)), including five percent of patients who achieved either a CR or CRp
• Median overall survival for the 47 FLT3-ITD positive patients who were bridged to a subsequent HSCT was 34.1 weeks, compared to 24.1 weeks for the 56 patients who achieved either a CRc or PR but did not undergo a subsequent  HSCT
• Median overall survival for the 33 FLT3-ITD positive patients who did not achieve at least a PR to quizartinib and did not undergo a subsequent HSCT was 8.9 weeks
• Twenty percent (27/136) FLT3-ITD positive patients remained alive for more than 12 months and were classified as long-term survivors
• All but one of the long-term survivors achieved at least a PR to quizartinib, with 63 percent (17/27) proceeding to a HSCT after quizartinib
• Ten of the 27 long-term survivors did not undergo a subsequent HSCT and had a median treatment duration of 53.5 weeks
• Quizartinib was generally well tolerated with manageable toxicity which included a grade 3 QTcF prolongation of 20 percent and no grade 4 QTcF prolongation events

Efficacy and Safety of Quizartinib (AC220) in Patients Age ≥60 Years with FLT3-ITD Positive Relapsed/Refractory Acute Myeloid Leukemia (AML)
Hartmut Dohner, M.D., Department of Internal Medicine III, University Hospital of Ulm, Ulm, Germany

Data from 110 FLT3-ITD positive patients, aged 60 years or older, who relapsed within one year or were refractory to first-line therapy were presented. Of the patients treated, 57 percent achieved a CRc, with seven percent having either a CR or CRp, with a median survival of 25.3 weeks. Additionally, 16 patients (15 percent) remained alive for more than 12 months and were classified as long-term survivors.

Additional key findings presented include:

• Of the 104 FLT3-ITD positive patients who lived at least 28 days to be assessed for response, the median overall survival for the 84 patients who achieved either a CRc or partial response (PR) to quizartinib is  31.1 weeks, compared to 11.8 weeks for the 20 patients who did not achieve at least a PR to quizartinib
• Median overall survival was 25.3 weeks for all patients, with a median of 22.7 weeks for patients age 70 years or older
• All patients who were long-term survivors achieved either a CRc or PR to quizartinib, with 52.1 weeks as median duration of treatment
• Quizartinib was generally well tolerated, with a 30-day mortality rate of five percent

SOURCE Ambit Biosciences Corporation