The European Medicines Agency (EMA) validated for review and granted accelerated assessment to the Marketing Authorization Application for quizartinib, an investigational oral selective FLT3 inhibitor being developed by Daiichi Sankyo for the treatment of adults with relapsed or refractory acute myeloid leukemia (AML) which is FLT3-ITD positive.

Acute myeloid leukemia is an aggressive blood and bone marrow cancer that causes uncontrolled growth and accumulation of malignant white blood cells that fail to function normally and interfere with the production of normal blood cells. [1] FLT3 is a receptor tyrosine kinase with important roles in hematopoietic stem/progenitor cell survival and proliferation and FLT3 gene mutations are one of the most common genetic abnormalities in acute myeloid leukemia.[2] Furthermore, FLT3-ITD is the most common FLT3 mutation, affecting approximately one in four patients with acute myeloid leukemia. [3][4][5][6] FLT3-ITD is a driver mutation that presents with high leukemic burden and has poor prognosis and a significant impact on disease management for patients with acute myeloid leukemia.[4][7]


The accelerated assessment of the quizartinib MAA underscores the significant unmet need for patients with relapsed/refractory FLT3-ITD Acute Myeloid Leukemia (AML)…


Patients with FLT3-ITD acute myeloid leukemia have a worse overall prognosis, including an increased incidence of relapse, an increased risk of death following relapse and a higher likelihood of relapse following hematopoietic stem cell transplantation as compared to those without this mutation.[8][9] This has led to the development of a number of small molecule tyrosine kinase inhibitors (TKI) with activity against FLT3.[2]

Validation
The validation confirms that the application is complete and commences the scientific review process by the EMA’s Committee for Medicinal Products for Human Use (CHMP). In addition, accelerated assessment is given to products expected to be of major interest for public health and therapeutic innovation and can significantly reduce the review timelines.

Marketing Authorization Application
The European Marketing Authorization Application is based on results of the pivotal phase III QuANTUM-R study of quizartinib, which was the first randomized Phase III study to show that a FLT3 inhibitor prolonged overall survival as an oral, single agent compared to chemotherapy in patients with relapsed/refractory FLT3-ITD AML.

The topline results of the phase III QuANTUM-R study were presented during the plenary program at the 23rd Congress of the European Hematology Association in June 2018.

Unmet need
“The accelerated assessment of the quizartinib Marketing Authorization Application underscores the significant unmet need for patients with relapsed/refractory FLT3-ITD acute myeloid leukemia, a very aggressive form of the disease with no approved targeted treatment options in Europe,” said Arnaud Lesegretain, Vice President, Oncology Research and Development and Head, AML Franchise, Daiichi Sankyo.

“Achieving both these milestones are significant next steps and we look forward to working with the EMA to bring this important potential new targeted treatment option to patients in the EU,” Lesegretain added.

Adverse events
In the QuANTUM-R study, the median treatment duration with quizartinib was 4 cycles of 28 days each versus 1 cycle in the salvage chemotherapy arm. Incidence of treatment-emergent adverse events was comparable between patients who received single agent quizartinib and those who received salvage chemotherapy.

The most common adverse drug reactions (>30%, any Grade) in patients treated with quizartinib included infections, bleeding, nausea, asthenic conditions, pyrexia, febrile neutropenia and vomiting, and the most common Grade ? 3 adverse drug reactions (>20%) were infection and febrile neutropenia.

The most common laboratory adverse reactions (incidence >50%) were decreased white blood cell count, decreased lymphocyte count, decreased hemoglobin, decreased neutrophil count and decreased platelet count. The safety profile observed in QuANTUM-R appears consistent with that observed at similar doses in the quizartinib clinical development program.

Other reviews
Quizartinib has been granted Breakthrough Therapy designation for the treatment of adult patients with relapsed/refractory FLT3-ITD acute myeloid leukemia, and Fast Track designation for the treatment of relapsed/refractory AML by the U.S. Food and Drug Administration (FDA).

Quizartinib also has been granted Orphan Drug designation by both the FDA and the European Commission (EC) for the treatment of acute myeloid leukemia and by the Japan Ministry of Health, Labour and Welfare (MHLW) for the treatment of FLT3-mutated acute myeloid leukemia.

Clinical trial
QuANTUM-R: An Open-label Study of Quizartinib Monotherapy vs. Salvage Chemotherapy in Acute Myeloid Leukemia (AML) Subjects Who Are FLT3-ITD Positive – NCT02039726

References
[1] Leukemia & Lymphoma Society. Facts 2015-2016. 2016. Online. Last accessed November 5, 2018
[2] Small D. Am Soc Hematol Educ Program. 2006;178-184.
Small D. FLT3 mutations: biology and treatment. Hematology Am Soc Hematol Educ Program. 2006:178-84. [PubMed][Article]
[3] Schneider F, Hoster E, Schneider S, Dufour A, Benthaus T, Kakadia PM, Bohlander SK, Braess J, et al. Age-dependent frequencies of NPM1 mutations and FLT3-ITD in patients with normal karyotype AML (NK-AML).Ann Hematol. 2012 Jan;91(1):9-18. doi: 10.1007/s00277-011-1280-6. Epub 2011 Jul 9.[Pubmed][Article]
[4] Santos FP, Jones D, Qiao W, Cortes JE, Ravandi F, Estey EE, Verma D, Kantarjian H, Borthakur G. Prognostic value of FLT3 mutations among different cytogenetic subgroups in acute myeloid leukemia. Cancer. 2011 May 15;117(10):2145-55. doi: 10.1002/cncr.25670. Epub 2010 Nov 29.[PubMed][Article]
[5] Kainz B, Heintel D, Marculescu R, Schwarzinger I, Sperr W, Le T, Weltermann A, Fonatsch C, Haas OA, et al. Variable prognostic value of FLT3 internal tandem duplications in patients with de novo AML and a normal karyotype, t(15;17), t(8;21) or inv(16).Hematol J. 2002;3(6):283-9.[PubMed]
[6] Kottaridis PD, Gale RE, Frew ME, Harrison G, Langabeer SE, Belton AA, Walker H, Wheatley K, et al. The presence of a FLT3 internal tandem duplication in patients with acute myeloid leukemia (AML) adds important prognostic information to cytogenetic risk group and response to the first cycle of chemotherapy: analysis of 854 patients from the United Kingdom Medical Research Council AML 10 and 12 trials. Blood. 2001 Sep 15;98(6):1752-9.[PubMed][Article]
[7] Zarrinkar PP, Gunawardane RN, Cramer MD, Gardner MF, Brigham D, Belli B, Karaman MW, Pratz KW, et al. AC220 is a uniquely potent and selective inhibitor of FLT3 for the treatment of acute myeloid leukemia (AML). Blood. 2009 Oct 1;114(14):2984-92. doi: 10.1182/blood-2009-05-222034. Epub 2009 Aug 4.[PubMed][Article]
[8] Wagner K, Damm F, Thol F, G?hring G, G?rlich K, Heuser M, Sch?fer I, Schlegelberger B, et al. FLT3-internal tandem duplication and age are the major prognostic factors in patients with relapsed acute myeloid leukemia with normal karyotype. Haematologica. 2011 May;96(5):681-6. doi: 10.3324/haematol.2010.034074. Epub 2011 Jan 17.[PubMed][Article]
[9] Brunet S, Labopin M, Esteve J, Cornelissen J, Soci? G, Iori AP, Verdonck LF, Volin L,et al. Impact of FLT3 internal tandem duplication on the outcome of related and unrelated hematopoietic transplantation for adult acute myeloid leukemia in first remission: a retrospective analysis. J Clin Oncol. 2012 Mar 1;30(7):735-41. doi: 10.1200/JCO.2011.36.9868. Epub 2012 Jan 30.[PubMed][Article]


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