Tag Archive for: Quizartinib

The Importance of the FLT3 Mutation In AML

The Importance of the FLT3 Mutation In AML from Patient Empowerment Network on Vimeo.

What do acute myeloid leukemia (AML) patients need to  know about FLT3 mutation? Dr. Naval Daver from the University of Texas MD Anderson Cancer Center discusses considerations about the mutation. Learn about the incidence of the FLT3 mutation, risk of relapse, and treatment options.

[ACT]IVATION TIP from Dr. Daver: “ it is very important to know the status of the FLT3 the mutation, both in diagnosis to see if one would benefit by the addition of the FLT3 inhibitor to the frontline induction chemo as well as in relapse because this would open up the option for FLT3  inhibitor targeted therapies, which would probably have the best chance of response and long-term outcomes. 

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Dr. Daver, for AML with a FLT3 mutation, what have we learned, and what is currently being investigated?

Dr. Naval Daver:

AML with the FLT3 mutation is very important from both prognostic and from therapy perspective, prognostically, this is considered to be one of the high-risk mutations, it’s also one of the most frequent mutations in AML in, seen in about 30 to 35 percent of younger and about 15 to 20 percent of older patients with AML, and these patients often have very prolific disease, elevated white count leukocytosis. And without the addition of FLT3 inhibitors, there is a high risk of relapse and a short overall survival. 

Over the last 15 years, a number of targeted therapies called the FLT3 inhibitors have emerged, these started with the first-generation FLT3 inhibitors drugs, such as lestaurtinib and sorafenib (Nexavar), now we have the second-generation FLT3 inhibitors, this includes drugs like gilteritinib (Xospata), quizartinib, and crenolanib which are more potent, specific, and better tolerated.

The first study that showed that the incorporation of FLT3 inhibitors improves outcome was a study called RATIFY Study, this is a frontline study looking at newly diagnosed FLT3 mutated younger patients where we added the FLT3 inhibitor midostaurin (Rydapt or Tauritmo), which is the first-generation FLT3 inhibitor to the standard induction chemo versus a placebo, added to standard induction chemo, induction chemo being standard of care to that time and this showed that in the addition of FLT3 inhibitor to induction chemo did improve remission rates and overall survival as compared to induction, and led to the approval of the FLT3 inhibitor midostaurin in the frontline setting. 

Since then, two other FLT3 inhibitors, second-generation potent FLT3 inhibitors drugs called gilteritinib, and lestaurtinib have also been evaluated. Gilteritinib, in a relapsed setting where single-agent gilteritinib, has given 50 to 60 percent response rates and has been extremely well-tolerated and much better than any other salvage treatment in the FLT3 space that we have ever seen, and in the frontline setting quizartinib and second-generation inhibitor also very recently, just a few months ago, there was data showing the combination of his art with intensive chemotherapy improved survival as compared to intensive chemotherapy alone. 

And so we think we are…they will be a third for the inhibitor to get approved, so there’s been a lot of progress overall in the three space, and there are other newer FLT3 inhibitors also in early clinical investigation that we think could eventually be as part or even better, the activation point related to this question is that, for the inhibitors have dramatically improved outcomes, both in the frontline setting when added to traditional backbone intensive chemotherapy as well as potentially lower intensity therapy, as well as in the relapsed refractory setting, and it is very important to know the status of the FLT3 the mutation, both in diagnosis to see if one would benefit by the addition of the FLT3 inhibitor to the frontline induction chemo as well as in relapse because this would open up the option for FLT3  inhibitor targeted therapies, which would probably have the best chance of response and long-term outcomes. 

Quizartinib in FLT3-ITD-Positive AML


I generally think of treatments for AML as old, meaning they were around when I was diagnosed in 1992, or new ones that were developed after that. In the first 25 or so years since I was diagnosed, there were very few new treatments. In the last 5-7 years, however, there have been several new treatments. There are targeted treatments like, Ivosidenib (which I wrote about in November: Ivosidenib and Azacitidine for IDH1-Mutated AML) as well as Ventoclax which is used with a number of different drugs (Azacitidine, Decitibine and low dose Ara C). This post is about a new (to the U.S. anyway) drug, Quizartinib, which is used in AML patients who have a specific mutation FLT3 (fms-like tyrosine kinase 3), specifically a FLT3-ITD (internal tandem duplication) mutation. 

Overview of FLT-3 

There are two different mutations in the FLT3 gene, ITD and tyrosine kinase domain mutations (TKD). The most common mutation in AML is in the FLT3 gene. About 30% of AML patients have an FlT3 mutation, with FLT3-ITD mutations more common than FLT3-TKD ones. Some of the existing drugs for FLT3 mutations treat both. Midostaurin (Rydapt) and Gilteritinib (Xospata) are used in patients with either FLT3 mutation. Quizartinib is only used to treat patients with a FLT3-ITD mutation. 

Current Study of Quizartinib 

The current study, the results of which were presented at the 2022 European Hematology Association (EHA) Annual Meeting in Vienna, tested standard chemotherapy with Quizartinib or with a placebo, followed by maintenance with Quizartinib or placebo for 3 years. More than 500 patients with a FLT3-ITD mutation were treated in the trial. Quizartinib or a placebo were added to the “7+3” standard induction therapy, which consists of 7 days of cytarabine (Ara-C) plus 3 days of daunorubicin or idarubicin. Patients who were in remission after induction either went on to up to 4 rounds of high dose cytarabine consolidation with Quizartinib or placebo and/or an allogeneic (donor) stem cell transplant, followed by up to 3 years of maintenance therapy with Quizartinib or placebo. 

The patients who received Quizartinib had a median overall survival of more than double the patients who received the placebo. Almost all patients in both arms experienced side effects of the treatment (emergent adverse events or AEs). This is not a surprise, most patients treated for AML have significant side effects. Patients who received Quizartinib had more side effects, in particular there was a higher incidence of significant neutropenia (low white counts) and more patients who received Quizartinib discontinued treatment because of adverse events. There were 56 treatment related deaths in the trial, somewhat more in those who received Quizartinib. 

Quizartinib looks like a promising treatment for FLT3-ITD AML patients. I believe that this is the only randomized (Phase III) trial that has been completed of a drug that treats mutations in the FLT-3 gene along with standard chemotherapy. It will be interesting to see how it compares to other drugs for patients with FLT-3 mutations. On the downside, it is only used for FLT3-ITD mutations, unlike Midostaurin and Gilteritinib. 

Further Reading 

Quizartinib Doubles Overall Survival in FLT3-ITD-Positive AML, article from Medscape on the trial of Quizartinib and Chemotherapy, June 13, 2022. 

Quizartinib Prolonged Survival VS Placebo Plus Intensive Induction and Consolidation Therapy Followed by Single-Agent Continuation in Patients Aged 18-75 Years With Newly Diagnosed FLT3-ITD+ AML, from 2022 European Hematology Association (EHA) Annual Meeting in Vienna. 

Daiichi Sankyo’s survival data mean it may finally be ready to compete with Novartis’, Astellas’ marketed AML meds, an article from Fierce Biotech, which covers the biotechnology industry. 

Xospata FDA Approval History, from Drugs.com, gives a history of the FDA approval of Xospata (gilteritinib). 

Overcoming Resistance: FLT3 Inhibitors Past, Present, Future and the Challenge of Cure, Capelli, D.; Menotti, D.; Fiorentini, A.; Saraceni, F.; Olivieri, A. Cancers 2022, 14, 4315. A long journal article on treating FLT-3 AML (I have not read all of it). 

FLT3 Inhibitor Quizartinib Improves Survival in AML reports on an older study showing patients with relapsed/refractory FLT3-ITD-positive AML have improved survival with Quizartinib, given as a single agent compared with standard-of-care chemotherapy. Medscape, July 02, 2018.