Quizartinib 17.7mg tablets

Topic: 4. Acute myeloid leukemia - Clinical Background: Inhibition of FLT3 and other kinases through oral targeted agents could improve standard chemotherapy outcomes for fit AML FLT3 wild type (WT) patients. The randomized SORAML trial from the SAL group, including FLT3-ITD mutated and WT, showed that the addition of type II inhibitor sorafenib improved leukemia-free, but not overall survival (OS) among newly diagnosed fit AML patients. Quizartinib (Quiz) is a potent type II inhibitor showing complete remissions (CR) as monotherapy for relapsed/refractory. With this rationale, the PETHEMA group designed a randomized, double-blind, placebo (PBO)-controlled phase II QUIWI trial (NCT04107727). Aims: The primary objective of QUIWI trial was to compare the event-free survival (EFS) (failure to achieve CR/CRi after 1 or 2 cycles, death in CR/CRi, or relapse, whichever occurs the first) between Quiz and PBO arms. We report here a preplanned interim analysis occurring 12 months after last patient inclusion. Methods: Multicenter, randomized, PBO-controlled, double-blinded phase II clinical trial. Patients with newly diagnosed FLT3-ITD WT AML, aged 18 to 70 years, and fit for intensive chemotherapy were centrally screened for FLT3-ITD prior to randomization. The trial was conducted in two phases: an open-label safety run-in phase exploring Cytarabine 200 mg/m2 (days 1-7), Idarubicin 12 mg/m2 (days 1-3), and Quiz 60 mg/d x 14 days to establish the dose for the randomized phase. The double-blinded phase 2:1 used randomization stratified by age (<60 vs. ≥60 years old) at diagnosis. A second identical induction cycle was allowed in case of failure to achieve CR/CRi after the first cycle. Consolidation (up to 4 cycles) consisted of high dose Cytarabine on Days 1, 3, and 5 plus Quiz or PBO for 14 days. Patients with high genetic risk or intermediate with MRD positivity were recommended for allo-SCT. A 12 cycles maintenance phase with 60 mg Quiz or PBO started after the consolidation or after allo-SCT. MRD monitoring, was performed through the PETHEMA centralized platform. NPM1 and CBF patients was assessed for MRD using RT-qPCR standardized techniques, and the remaining subgroups by standardized multiparametric flow cytometry. Results: From September 2019 to November 2021, 284 Pts were enrolled in 45 Spanish PETHEMA centers, 11 of them were included in the safety run-in phase establishing 60 mg/day of Quiz or PBO for the randomized phase. 273 Pts were randomized to Quiz (n=180) or PBO (n=93). The median age was 57 y [IQR, 48 – 64 y]. Baseline pts and disease characteristics were balanced between the 2 arms. At data cutoff (February 2023), the median follow-up was 17 months. Median EFS was 16.6 mo with Quiz vs 10.6 mo with PBO (hazard ratio [HR], 0.729; 95% CI, 0.522-1.018; 2-sided P=0.062) (Figure 1A). Regarding OS, 50 out of 180 patients died in the Quiz arm, and 45 out of 93 in the PBO. Median OS was not reached with Quiz vs 15 mo with PBO (HR, 0.558; 95% CI, 0.373-0.834; P=0.004), and the 2-years OS was 63.5% with Quiz vs 47% with PBO. (Figure1B). Disease-free survival was not reached with Quiz vs 15.4 mo with PBO (HR 0.643; 95% CI 0.411-1.005; P=0.050). CR/CRi rate after 2 cycles was 76.7% in the Quiz arm and 76.4% in the PBO. CR/CRi with MRD negativity after 2 cycles was achieved in 41.5% in the Quiz arm and 41.6% in the PBO. No new safety signals were observed among Quiz arm. Summary/Conclusion: Our study suggests that the addition of Quiz to 3 + 7 may prolong OS in newly diagnosed FLT3-ITD WT AML. A large biomarker plan to clarify underlying molecular mechanisms and final analyses with longer follow-up will be reported by the end of 2023.Keywords: flt3 inhibitor, Treatment, Clinical trial, Acute myeloid leukemia

Abstract licence: CC BY-NC-ND

Mutations in FMS-related receptor tyrosine kinase 3 (FLT3) are among the most common alterations in acute myeloid leukemia (AML), present in ≈30% of newly diagnosed AML cases. Internal tandem duplications (ITD) in FLT3 (FLT3-ITD) occur in ≈25% of newly diagnosed AML cases and are associated with unfavorable outcomes. Quizartinib (formerly AC220) is a novel, second-generation, highly potent, and selective type II FLT3 inhibitor. Quizartinib is approved in Japan as monotherapy for the treatment of adult patients with FLT3-ITD-positive relapsed/refractory (R/R) AML. Quizartinib is also approved in the United States, Japan, Europe, and United Kingdom in combination with chemotherapy during induction and consolidation, and as maintenance monotherapy (but, in the United States, not after allogeneic hematopoietic cell transplantation [allo-HCT]), for the treatment of adult patients with newly diagnosed FLT3-ITD-positive AML. In this review, we summarize preclinical studies that established quizartinib as a potent and selective type II FLT3 inhibitor as well as early and pivotal phase 3 clinical studies (QuANTUM-R and QuANTUM-First) that led to the approvals of quizartinib. We also summarize mechanisms of resistance to quizartinib along with its safety profile. Furthermore, we review the ongoing post hoc analyses of the QuANTUM-First data elucidating the impact of allo-HCT, the presence of measurable residual disease, and number and length of ITD on the clinical outcomes of quizartinib. We also describe the impact of quizartinib on patient-reported outcomes. Finally, we highlight some of the ongoing studies that test quizartinib in patients with FLT3-ITD-positive AML, patients with FLT3-ITD-negative AML, in both the first-line and R/R settings, in patients fit or unfit for intensive chemotherapy, including studies for quizartinib-based combination with other compounds such as decitabine and venetoclax. Future research should aim to further optimize the clinical value of quizartinib and explore its use in additional clinical settings, which could be achieved by testing quizartinib with other drugs, better characterization of the mechanisms of resistance, identification of the role of quizartinib as a maintenance therapy after allo-HCT, and investigating quizartinib in patients with FLT3-ITD-negative AML.

Abstract licence: CC BY-NC-ND

FLT3 mutations are among the most common genetic alterations in acute myeloid leukemia (AML) and are associated with poor prognosis. Significant advancements have been made in developing FLT3 inhibitors (FLT3Is), such as quizartinib, which have improved treatment outcomes in both newly diagnosed and relapsed/refractory AML. Resistance to FLT3Is remains a major clinical challenge, driven by diverse mechanisms including FLT3 point mutations, cellular escape pathways, and the influence of the bone marrow microenvironment. Sustained STAT5 phosphorylation, AXL upregulation, and CXCR4 signaling have been identified as key factors in FLT3I resistance. Additionally, metabolic adaptations have been shown to support the survival of FLT3I-resistant cells. Ongoing clinical trials are investigating various combination regimens, including quizartinib with chemotherapy, Bcl-2 inhibitors, hypomethylating agents, and immune-modulatory drugs, with promising preliminary results. The European LeukemiaNet 2022 guidelines recommend incorporating FLT3Is into treatment regimens; however, questions remain regarding the best timing for the administration of each FLT3I. Additional studies are required to determine the optimal FLT3I-based combinations, reduce resistance emergence, and improve outcomes. This review highlights the current state of FLT3I therapy, ongoing challenges with resistance, and future directions in optimizing treatment for FLT3-mutated AML, focusing on quizartinib.

Abstract licence: CC BY-NC

BACKGROUND: Despite initial success with FLT3 inhibitors (FLT3is), outcomes for FLT3-ITD acute myeloid leukemia (AML) patients remain unsatisfactory, underscoring the need for more effective treatment options. Epigenetic modifications, such as histone acetylation, contribute to AML's onset and persistence, advocating the potential for epigenetic therapies. However, the poor specificity of pan-histone deacetylase inhibitors (HDACis) leads to undesirable adverse effects, prompting the need for isoform-specific HDACis. This study aims to explore the antileukemic activities and mechanisms of IHCH9033, a novel class I HDACi, alone or combined with FLT3i in FLT3-ITD AML. METHODS: The viability of AML cell lines and primary AML cells treated with HDACis alone or in combination with FLT3i was detected by MTT or CCK8 assay. Flow cytometry was utilized to examine cell apoptosis, cell cycle progression and ROS production. RNA sequencing analysis, RT-qPCR, western blotting, and co-immunoprecipitation assays were employed to elucidate the molecule mechanisms. The in vivo anti-leukemia efficacy was tested in xenografted mice models derived from FLT3-ITD cell lines and primary AML patients. RESULTS: Here, we identified IHCH9033, a novel selective class I HDACi, which exhibited an increased antitumor effect in FLT3-ITD AML through effectively eliminating leukemia burden and overcoming resistance to FLT3i. Mechanically, IHCH9033 selectively inhibited DNA repair in FLT3-ITD AML cells, leading to the accumulation of DNA damage that eventually resulted in cell cycle arrest and apoptosis. Additionally, IHCH9033 induced HSP90 acetylation, FLT3 ubiquitination, and proteasomal degradation of FLT3, thereby inhibiting FLT3 downstream signaling. Notably, IHCH9033 maintained its potency in both FLT3i-resistant AML cell lines and primary-resistant patient samples, and exerted strong synergy with the FLT3i quizartinib, leading to tumor regression in FLT3-ITD/TKD AML xenografts. In patient-derived xenografts, the treatment with IHCH9033, both alone and in combination, led to nearly complete eradication of the AML burden, without significant adverse effects. CONCLUSIONS: Our study shows that IHCH9033, a novel class I HDACi with a desirable pharmacological profile, is a promising drug candidate for FLT3-ITD AML, and suggests a strategy of combining class I HDACis and FLT3is in AML clinical trials to increase efficacy and overcome resistance, thus potentially providing a curative treatment option.

Abstract licence: CC BY