Efficacy and safety of quizartinib in Japanese patients with FLT3-ITD positive relapsed or refractory acute myeloid leukemia in an open-label, phase 2 study

• Published in: International journal of hematology 2019-12, Vol.110 (6), p.665-674
• Main Authors: Takahashi, Takeshi, Usuki, Kensuke, Matsue, Kosei, Ohno, Hitoshi, Sakura, Toru, Imanaka, Ryota, Murakami, Masato, Ohwada, Shoichi, Takagi, Taiga, Sakajiri, Sakura
• Format: Article
• Language: English
• Subjects: Acute myeloid leukemia; Aged; Arrhythmia; Benzothiazoles - adverse effects; Benzothiazoles - pharmacology; Benzothiazoles - therapeutic use; Confidence intervals; Effectiveness; Female; Flt3 protein; fms-Like Tyrosine Kinase 3 - genetics; Hematology; Humans; Japan; Kinases; Leukemia; Leukemia, Myeloid, Acute - complications; Leukemia, Myeloid, Acute - drug therapy; Leukemia, Myeloid, Acute - mortality; Male; Medicine; Medicine & Public Health; Middle Aged; Mutation; Myeloid leukemia; Neutropenia; Oncology; Original Article; Patients; Phenylurea Compounds - adverse effects; Phenylurea Compounds - pharmacology; Phenylurea Compounds - therapeutic use; Protein Kinase Inhibitors - therapeutic use; Protein-tyrosine kinase; Remission; Remission Induction - methods; Safety; Salvage Therapy - adverse effects; Salvage Therapy - methods; Salvage Therapy - mortality; Survival; Treatment Outcome; Tyrosine
• ISSN: 0925-5710; 1865-3774
• DOI: 10.1007/s12185-019-02727-6

FMS-like tyrosine kinase 3 ( FLT3 ) internal tandem duplication (ITD) mutations in patients with acute myeloid leukemia (AML) are associated with early relapse and poor survival. This multicenter, single-arm, two-stage phase 2 study (NCT02984995) was conducted to evaluate the efficacy and safety of quizartinib hydrochloride (initial dose 20/30 mg/day), an oral, highly potent, selective FLT3 inhibitor in Japanese patients (median age 65 years) with FLT3 -ITD positive relapsed/refractory (R/R) AML. The composite complete remission (CRc) rate (primary endpoint) was 53.8% (90% confidence interval 36.2–70.8%) for evaluable patients in the efficacy analysis set. The median duration of CRc and overall survival was 16.1 weeks and 34.1 weeks, respectively. The most frequent treatment-emergent adverse events (TEAEs) were febrile neutropenia (43.2%), platelet count decreased (37.8%), and QT prolonged (35.1%). Two (5.4%) patients experienced TEAEs associated with treatment discontinuation. All serious TEAEs (45.9%), except febrile neutropenia (16.2%), were reported in ≤ 2 patients. The incidence of QTcF 451–480 ms and 481–500 ms was 37.8% and 2.7%, respectively. No QTcF > 500 ms, events of torsade de pointes or arrhythmia with clinical symptoms were reported. Quizartinib monotherapy was well tolerated and resulted in clinically meaningful reductions in blast count in Japanese patients with FLT3 -ITD R/R AML.