Remarkable Result for Ambit and Astellas AML Drug

Final results of a Phase II study of quizartinib were presented at the American Society of Hematology meeting in Atlanta which suggest that drug could be a good option to treat patients with treatment-resistant acute myeloid leukaemia (AML).

In the clinical study, the majority of participants carried a mutation in a gene called FLT3-ITD.  The FLT3 mutation, Mark Levis noted, is a “power switch” that leukaemia cells use to spread more aggressively, which helps them to grow back immediately after chemotherapy.

Levis added that the only way to treat this “is to find a way to turn the switch off – a feat that has eluded researchers” in the past.  While patients with the FLT3-ITD mutation can achieve remission with standard chemotherapy, they tend to relapse quickly.  Additionally, an important treatment option is a stem cell transplant, but only if the patient is in some form of remission, otherwise, failure rates are high.

Quizartinib is designed to ‘switch off’ the mutated FLT3 enzyme.  The Phase II study was conducted among 333 patients divided into two cohorts.  In the second cohort, involving 137 patients (99 with mutation and 38 without), a complete remission rate of 44% was observed in patients with the FLT3-ITD mutation with a median duration of response of 11.3 weeks and median overall survival of 23.1 weeks.  Even in those patients without the mutation, researchers observed a 34% complete response rate.

Quizartinib, is “the first and only single-agent drug that has produced a clinical benefit in AML patients with this deadly mutation who have failed previous therapy” Levis noted.  He commented that the number of patients “bridged to a stem cell transplant was very significant;” of the aforementioned 137 patients, 47 were able to receive a transplant after responding to quizartinib and 18 had survived 60 weeks after treatment with no disease recurrence.

The results of the trial were described as remarkable and Dr Levis said the Phase III clinical trials “will hopefully lead to the approval of quizartinib to make it accessible to those patients who previously had no hope for a cure.”

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