Gemtuzumab ozogamicin plus midostaurin in combination with standard '7 + 3' induction therapy in newly diagnosed AML: Results from the SAL-MODULE phase I study.

We conducted a phase I trial in newly diagnosed acute myeloid leukaemia (AML) to investigate the combination of two novel targeted agents, gemtuzumab ozogamicin (GO) and midostaurin, with intensive chemotherapy in FLT3-mutated AML and CBF leukaemia. Three dose levels of midostaurin and one to three sequential doses of 3 mg/m2 GO in combination with '7 + 3' induction were evaluated. Based on safety findings in 12 patients, our results show that 3 mg/m2 GO on Days 1 + 4 and 100 mg midostaurin on Days 8-21 can be safely combined with IC in newly diagnosed AML.

Quantification of midostaurin in plasma and serum by stable isotope dilution liquid chromatography-tandem mass spectrometry: Application to a cohort of patients with acute myeloid leukemia.

OBJECTIVES: Midostaurin is an oral multitargeted tyrosine kinase inhibitor for the treatment of acute myeloid leukemia (AML). Therapeutic drug monitoring of midostaurin may support its safe use when suspecting toxicity or combined with strong CYP3A4 inhibitors. METHODS: A stable isotope dilution liquid chromatography-tandem mass spectrometry method was developed and validated for the determination and quantification of midostaurin in human plasma and serum. Midostaurin serum concentrations were analyzed in 12 patients with FMS-like tyrosine kinase 3 (FLT3)-mutated AML during induction chemotherapy with cytarabine, daunorubicin, and midostaurin. Posaconazole was used as prophylaxis of invasive fungal infections. RESULTS: Linear quantification of midostaurin was demonstrated across a concentration range of 0.01-8.00 mg/L. Inter- and intraday imprecisions of the proposed method were well within ±10%. Venous blood samples were taken in nine and three patients in the first and second cycle of induction chemotherapy. Median (range) midostaurin serum concentration was 7.9 mg/L (1.5-26.1 mg/L) as determined in 37 independent serum specimens. CONCLUSION: In a real-life cohort of AML patients, interindividual variability in midostaurin serum concentrations was high, highlighting issues concerning optimal drug dosing in AML patients. A personalized dosage approach may maximize the safety of midostaurin. Prospective studies and standardization of analytical methods to support such an approach are needed.

Midostaurin drug interaction profile: a comprehensive assessment of CYP3A, CYP2B6, and CYP2C8 drug substrates, and oral contraceptives in healthy participants.

PURPOSE: Midostaurin, approved for treating FLT-3-mutated acute myeloid leukemia and advanced systemic mastocytosis, is metabolized by cytochrome P450 (CYP) 3A4 to two major metabolites, and may inhibit and/or induce CYP3A, CYP2B6, and CYP2C8. Two studies investigated the impact of midostaurin on CYP substrate drugs and oral contraceptives in healthy participants. METHODS: Using sentinel dosing for participants' safety, the effects of midostaurin at steady state following 25-day (Study 1) or 24-day (Study 2) dosing with 50 mg twice daily were evaluated on CYP substrates, midazolam (CYP3A4), bupropion (CYP2B6), and pioglitazone (CYP2C8) in Study 1; and monophasic oral contraceptives (containing ethinylestradiol [EES] and levonorgestrel [LVG]) in Study 2. RESULTS: In Study 1, midostaurin resulted in a 10% increase in midazolam peak plasma concentrations (Cmax), and 3-4% decrease in total exposures (AUC). Bupropion showed a 55% decrease in Cmax and 48-49% decrease in AUCs. Pioglitazone showed a 10% decrease in Cmax and 6% decrease in AUC. In Study 2, midostaurin resulted in a 26% increase in Cmax and 7-10% increase in AUC of EES; and a 19% increase in Cmax and 29-42% increase in AUC of LVG. Midostaurin 50 mg twice daily for 28 days ensured that steady-state concentrations of midostaurin and the active metabolites were achieved by the time of CYP substrate drugs or oral contraceptive dosing. No safety concerns were reported. CONCLUSION: Midostaurin neither inhibits nor induces CYP3A4 and CYP2C8, and weakly induces CYP2B6. Midostaurin at steady state has no clinically relevant PK interaction on hormonal contraceptives. All treatments were well tolerated.

Gilteritinib clinical activity in relapsed/refractory FLT3 mutated acute myeloid leukemia previously treated with FLT3 inhibitors.

Gilteritinib is approved for the treatment of relapsed/refractory (R/R) acute myeloid leukemia (AML) with an FLT3-mutation (FLT3mut+ ). However, the gilteritinib phase 3 ADMIRAL study (Perl et al NEJM 2019) was conducted prior to widespread adoption of either midostaurin as a component of standard intensive induction and consolidation or posttransplant FLT3 inhibitor maintenance. We performed a retrospective analysis using data from 11 US centers and where we identified 113 patients who received gilteritinib alone or as combination therapy for the treatment of R/R FLT3mut+ AML. The composite complete remission (CR) rate (CRc, defined as CR + CRi + CR with incomplete platelet recovery [CRp]) was 48.7% (n = 55). The CRc rate after treatment with gilteritinib in patients who were treated with only prior 7+3 and midostaurin with or without consolidation was 58% with a median survival of 7.8 months. Survival was longest in patients who obtained a CR, particularly a cMRD (clinical minimal or measurable residual disease) negative response; this remained significant after censoring at the time of stem cell transplant. The mitogen-activated protein kinase pathway activating mutations that are known for gilteritinib resistance (NRAS, KRAS, and PTPN11) had lower CRc (35% vs. 60.5%) and lower median overall survival than patients' whose leukemia did not express these mutations (4.9 months vs. 7.8 months) (HR 2.4; 95% CI 1. 5.4) p value <.01.

Use of midostaurin in mixed phenotype acute leukemia with FLT3 mutation: A case series.

Mixed phenotype acute leukemia (MPAL) is a rare type of acute leukemia where blasts present phenotypes from more than one lineage. A poor prognostic has been associated with this disease, and limited data are currently available to guide the choice of therapy. Regarding FLT3-positive MPAL, only one case treated with midostaurin has been published to date. Here, we report the successful use of midostaurin to treat three FLT3-positive MPAL T/myeloid and B/myeloid patients. Midostaurin was successfully added to intensive induction (two patients) and consolidation chemotherapy (three patients) without significant adverse events requiring a dose adjustment or discontinuation. The therapy received resulted in complete remission for two patients and complete remission with an incomplete hematologic recovery for the third. All patients proceeded to HSCT and stayed in remission after an extended follow-up respectively at 28, 31, and 11 months later. These results suggest that the addition of midostaurin during induction and consolidation therapy may represent a treatment option for FLT3-positive MPAL.

The safety profile of FLT3 inhibitors in the treatment of newly diagnosed or relapsed/refractory acute myeloid leukemia.

INTRODUCTION: FLT3 inhibitors are important drugs in the therapy of FLT3 positive acute myeloid leukemia (AML). Midostaurin was registered in combination with chemotherapy to treat newly diagnosed AML. Gilteritinib and quizartinib demonstrate effectiveness in a randomized trial in relapsed/refractory AML. Several promising FLT3 inhibitors are being evaluated in clinical research. AREAS COVERED: This review will report the safety of FLT3 inhibitors that are registered for acute myeloid leukemia induction and rescue therapy. EXPERT OPINION: In the near future, it is possible that all the FLT3 positive non M3-AML patients will receive a FLT3 inhibitor. Therapy adherence and strategies to mitigate adverse events must be pursued. The treatment with FLT3 inhibitors may be optimized in terms of toxicities with a rational evaluation of antifungal prophylaxis and concomitant therapy, cardiology monitoring, and keeping in mind rare adverse events. Future studies on unfit patients, special populations, and maintenance settings are warranted, together with post-market studies and real-life experiences. Whenever new FLT3 inhibitors will come to the clinic, we could face a scenario in which profound knowledge of effectiveness, toxicities, and off-target effects will be relevant to choose the best drug for each patient.

Clonal evolution of acute myeloid leukemia with FLT3-ITD mutation under treatment with midostaurin.

In the international randomized phase 3 RATIFY (Randomized AML Trial In FLT3 in patients less than 60 Years old) trial, the multikinase inhibitor midostaurin significantly improved overall and event-free survival in patients 18 to 59 years of age with FLT3-mutated acute myeloid leukemia (AML). However, only 59% of patients in the midostaurin arm achieved protocol-specified complete remission (CR), and almost half of patients achieving CR relapsed. To explore underlying mechanisms of resistance, we studied patterns of clonal evolution in patients with FLT3-internal tandem duplications (ITD)-positive AML who were entered in the RATIFY or German-Austrian Acute Myeloid Leukemia Study Group 16-10 trial and received treatment with midostaurin. To this end, paired samples from 54 patients obtained at time of diagnosis and at time of either relapsed or refractory disease were analyzed using conventional Genescan-based testing for FLT3-ITD and whole exome sequencing. At the time of disease resistance or progression, almost half of the patients (46%) became FLT3-ITD negative but acquired mutations in signaling pathways (eg, MAPK), thereby providing a new proliferative advantage. In cases with FLT3-ITD persistence, the selection of resistant ITD clones was found in 11% as potential drivers of disease. In 32% of cases, no FLT3-ITD mutational change was observed, suggesting either resistance mechanisms bypassing FLT3 inhibition or loss of midostaurin inhibitory activity because of inadequate drug levels. In summary, our study provides novel insights into the clonal evolution and resistance mechanisms of FLT3-ITD-mutated AML under treatment with midostaurin in combination with intensive chemotherapy.

Midostaurin in combination with chemotherapy is most effective in patients with acute myeloid leukemia presenting with high FLT3-ITD allelic ratio who proceed to allogeneic stem cell transplantation while in first complete remission.

OBJECTIVES: Midostaurin, a multikinase and FLT3 inhibitor, is the first non-chemotherapy agent approved and widely adopted for the treatment of FLT3-ITD acute myeloid leukemia (AML). Yet, its role in improving survival of patients referred to allogeneic stem cell transplantation (allo-SCT) in first complete remission (CR1) needs to be defined. METHODS: This multicenter study retrospectively evaluated the outcome of 119 FLT3-ITD AML patients [59 (49.6%) males and 60 females] intensively treated between 2015 and 2019 at five Israeli centers. In our cohort, allo-SCT in CR1 was widely implemented (47%) and patient stratification was based on the current allelic ratio (AR) cutoff of 0.5. RESULTS: Ninety-eight patients (82.3%) achieved CR1/CR with incomplete count recovery (CRi). Death during induction was reported in 7 (5.9%) patients. In multivariate analysis, midostaurin use and allo-SCT in CR1 were the most significant factors affecting overall survival (OS). Midostaurin incorporation in chemotherapy regimens significantly improved CR + CRi rates (P = .002), reduced relapse rates (P = .02), and was remarkably advantageous for high-AR patients (2-year OS 82%). In low-AR patients, the midostaurin effect was much less prominent. CONCLUSIONS: Our results demonstrate benefits of midostaurin incorporation in intensive chemotherapy regimens, particularly for high-AR AML patients to whom it should be offered along with allo-SCT in CR1.

A Phase II Study of Midostaurin and 5-Azacitidine for Untreated Elderly and Unfit Patients With FLT3 Wild-type Acute Myelogenous Leukemia.

BACKGROUND: Midostaurin, a multikinase inhibitor, is approved for treatment of FLT3-mutant acute myeloid leukemia (AML). A phase I study established that midostaurin 75 mg orally twice daily for 14 days with standard dose azacitidine was safe and tolerable in elderly patients with AML. Herein, we report the phase II expansion cohort of previously untreated elderly or unfit patients with AML. PATIENTS AND METHODS: Primary objectives were to further describe the toxicity profile and determine the response rate in untreated patients with AML. Patients received midostaurin 75 mg orally twice daily on days 8 to 21 in combination with intravenous azacitidine at 75 mg/m2 on days 1 to 7. Plasma inhibitory activity assay for FLT3 was performed pretreatment and on day 8 and day 15 of each cycle. RESULTS: Twenty-six patients (median age, 74 years; range, 59-85 years) with FLT3 wild-type AML were accrued. Patients received a median of 2 cycles of therapy (range, 1-10 cycles). Seven (29%) of 24 evaluable patients achieved a clinical response (4 complete response; 1 complete response with incomplete count recovery; and 2 partial response). The median overall survival was 244 days (95% confidence interval, 203-467 days). Hematologic, infectious, and gastrointestinal toxicities were comparable to similar studies. Peripheral blood FLT3 wild-type phosphorylation declined to 8% to 55% of pretreatment by day 15 of cycle 1 (7 patients) and declined with subsequent cycles (< 10% baseline) in 2 patients who were analyzed after cycle 3. CONCLUSION: Multiple cycles of azacitidine and midostaurin were not well-tolerated, but persistent inhibition of FLT3 wild-type phosphorylation suggest intermittent dosing of midostaurin should be considered in future low-intensity regimens for FLT3-mutant AML.

Midostaurin and cyclosporine drug interaction: A case report.

WHAT IS KNOWN AND OBJECTIVE: Allogeneic stem cell transplantation patients are often on immunosuppression including calcineurin inhibitors post-transplant for prevention of graft-versus-host disease. Recent data suggested that addition of midostaurin, a FLT-3 mutant kinase inhibitor, maintenance can reduce risk of relapse by 46% at 18 months post-transplant. CASE DESCRIPTION: Patient is a post-allogenetic stem cell transplant patient started on midostaurin for maintenance therapy. Patient had stable serum levels of cyclosporine with a sudden 70% increase in serum level shortly after starting midostaurin. Patient had no other medication changes or laboratory abnormalities that would suggest the change was caused by alternate factors. WHAT IS NEW AND CONCLUSION: This data suggest that midostaurin and cyclosporine have a possible previously unidentified drug interaction leading to elevation immunosuppression serum levels that need to be accounted for in practice.

MEK inhibition enhances the response to tyrosine kinase inhibitors in acute myeloid leukemia.

FMS-like tyrosine kinase 3 (FLT3) is a key driver of acute myeloid leukemia (AML). Several tyrosine kinase inhibitors (TKIs) targeting FLT3 have been evaluated clinically, but their effects are limited when used in monotherapy due to the emergence of drug-resistance. Thus, a better understanding of drug-resistance pathways could be a good strategy to explore and evaluate new combinational therapies for AML. Here, we used phosphoproteomics to identify differentially-phosphorylated proteins in patients with AML and TKI resistance. We then studied resistance mechanisms in vitro and evaluated the efficacy and safety of rational combinational therapy in vitro, ex vivo and in vivo in mice. Proteomic and immunohistochemical studies showed the sustained activation of ERK1/2 in bone marrow samples of patients with AML after developing resistance to FLT3 inhibitors, which was identified as a common resistance pathway. We examined the concomitant inhibition of MEK-ERK1/2 and FLT3 as a strategy to overcome drug-resistance, finding that the MEK inhibitor trametinib remained potent in TKI-resistant cells and exerted strong synergy when combined with the TKI midostaurin in cells with mutated and wild-type FLT3. Importantly, this combination was not toxic to CD34+ cells from healthy donors, but produced survival improvements in vivo when compared with single therapy groups. Thus, our data point to trametinib plus midostaurin as a potentially beneficial therapy in patients with AML.

Midostaurin in combination with intensive chemotherapy is safe and associated with improved remission rates and higher transplantation rates in first remission-a multi-center historical control study.

The addition of midostaurin, a FLT3-inhibitor, to intensive chemotherapy (IC) was previously shown to improve outcome of younger patients with FLT3-mutated AML. The toxicity and efficacy of adding midostaurin to IC in patients not originally included in the RATIFY study or with intensified daunorubicin dosing are unknown. We conducted a retrospective, multi-center, historical-control study to characterize the safety and efficacy of adding midostaurin to IC in a "real-world" setting. Sixty-nine adult patients were included in the analysis (midostaurin n = 34, historical controls n = 35) with a mean follow-up of 18.4 (± 15) months. Median age of patients was 60 (range 26-82) years; 32% and 20% of patients were > 65 and 70 years, respectively. No differences in baseline characteristics were noted between the groups. Midostaurin was administered with 90 mg/m2 daunorubicin in 29% of patients; One-third of patients experienced dose reductions/interruptions during midostaurin therapy. Overall toxicity was comparable between the midostaurin and control groups.CR/CRi rates were higher in patients treated with midostaurin compared with controls (80% vs. 57%, p = 0.047) and significantly more patients in the midostaurin group were transplanted in first remission (95% vs. 68%, p = 0.04).Median OS and DFS were higher in the midostaurin vs. control group (not reached vs. 11 months (p = 0.085) and 13 vs. 6 months (p = 0.09), respectively). In our analysis, midostaurin was not associated with increased toxicity including in older patients, in those with secondary AML or when administered with intensified daunorubicin dosage. Higher remission rates in the midostaurin group and increased transplantation rates in first CR were associated with a trend towards better outcomes.

Sorafenib plus intensive chemotherapy improves survival in patients with newly diagnosed, FLT3-internal tandem duplication mutation-positive acute myeloid leukemia.

BACKGROUND: The addition of midostaurin to induction chemotherapy improves survival in younger patients with newly diagnosed, FLT3-mutated acute myeloid leukemia (AML). Sorafenib is a potent multikinase inhibitor with efficacy when given as monotherapy. The authors investigated whether the addition of sorafenib to intensive induction chemotherapy improves outcomes in patients with FLT3-internal tandem duplication (ITD)-mutated AML. METHODS: In total, 183 patients who were newly diagnosed with FLT3-ITD-mutated AML between February 2001 and December 2017 were identified. Of these, 79 patients (43%) underwent intensive chemotherapy with the addition of sorafenib, and 104 (57%) received intensive chemotherapy alone. Propensity score matching identified 42 patients in each cohort. RESULTS: The overall response rate was 98% in the sorafenib cohort and 83% in the intensive chemotherapy cohort (P = .057). The median follow-up was 54 months. The median event-free survival was 35 months in the sorafenib cohort and 8 months in the intensive chemotherapy cohort (P = .019), and the median overall survival was 42 and 13 months, respectively (P = .026). With censoring at the time of allogeneic stem cell transplantation, the median event-free survival was 31 and 8 months in the sorafenib and intensive therapy cohorts, respectively (P = .031), and the median overall survival was not reached and 10 months, respectively (P = .001). Multivariate Cox proportional hazards models confirmed that treatment with sorafenib was a favorable prognostic factor (P = .009; hazard ratio, 0.558; 95% CI, 0.360-0.865). CONCLUSIONS: The addition of sorafenib improves survival in patients with FLT3-ITD-mutated AML regardless of whether they undergo allogeneic stem cell transplantation.

European Medicines Agency review of midostaurin (Rydapt) for the treatment of adult patients with acute myeloid leukaemia and systemic mastocytosis.

On 18 September 2017, a marketing authorisation valid through the European Union (EU) was issued for midostaurin in combination with standard daunorubicin and cytarabine induction and high-dose cytarabine consolidation chemotherapy and for patients in complete response followed by midostaurin single agent maintenance therapy, for adult patients with newly diagnosed acute myeloid leukaemia (AML) who are Fms-like tyrosine kinase 3 mutation positive and as monotherapy for the treatment of adult patients with aggressive systemic mastocytosis (ASM), systemic mastocytosis with associated haematological neoplasm (SM-AHN) or mast cell leukaemia (MCL). The recommended dose of midostaurin is 50 mg orally twice daily for AML and 100 mg orally twice daily for ASM, SM-AHN and MCL. Midostaurin was evaluated in two pivotal studies. Study A2301 (RATIFY) included 717 patients with AML. Overall survival (OS) was statistically significantly different between the two groups, and the median OS was 74.7 months in the midostaurin+daunorubicin+cytarabine group and 25.6 months in the placebo+daunorubicin+cytarabine group (HR 0.774; 95% CI 0.629 to 0.953; p=0.0078). Study D2201 included 116 patients with ASM, SM-AHN or MCL. An overall response rate, by IWG-MRT/ECNM (international working group - myelofibrosis research and treatment/European competence network on mastocytosis) criteria of 28.3% was observed in all patients and 60.0%, 20.8% and 33.3% in patients with ASM, SM-AHN and MCL respectively. The most common adverse drug reactions (ADRs) with midostaurin treatment in AML were febrile neutropenia, nausea, exfoliative dermatitis, vomiting, headache, petechiae and fever. In ASM, SM-AHN, MCL the most common ADRs were nausea, vomiting, diarrhoea, peripheral oedema and fatigue. The objective of this paper is to summarise the scientific review of the application leading to regulatory approval in the EU.

Cost Effectiveness of Midostaurin in the Treatment of Newly Diagnosed FLT3-Mutated Acute Myeloid Leukemia in the United States.

OBJECTIVES: The aim of this study was to assess the cost effectiveness of midostaurin + cytarabine + daunorubicin (midostaurin arm) versus placebo + cytarabine + daunorubicin (placebo arm) in the treatment of adult patients with newly diagnosed FLT3-mutated acute myeloid leukemia (AML) who are eligible for standard cytarabine + daunorubicin chemotherapy, from a US third-party payer perspective. METHODS: A lifetime partitioned survival model with four health states (active disease, complete remission [CR], relapse, and death) was constructed. Efficacy inputs (time to CR or death, time to relapse or death, and overall survival) were estimated using data from the RATIFY trial (NCT00651261). Costs (inflated to 2016 US dollars) included treatment, drug monitoring, stem cell transplantation (SCT), adverse events costs, and medical costs associated with health states. Incremental costs per quality-adjusted life-year (QALY) and life-year (LY) gained were estimated. Deterministic (DSA) and probabilistic sensitivity analyses (and PSA) were performed to assess model robustness. RESULTS: In the base case, patients in the midostaurin arm incurred higher total direct costs over a lifetime compared with the placebo arm ($4,043,470 vs. $3,959,741), resulting in an incremental cost of $83,729; however, the midostaurin arm had better effectiveness, with 1.59 more LYs and 1.37 more QALYs. These led to a base-case incremental cost-effectiveness ratio (ICER) of $52,596 per LY, or $61,167 per QALY. Results were robust in the DSA. In the PSA, the probability of the midostaurin arm being cost-effective compared with the placebo arm was 65.9%, at a willingness to pay of $150,000/QALY. CONCLUSIONS: This analysis suggests that midostaurin is a cost-effective treatment for adult patients with newly diagnosed FLT3-mutated AML, from a US third-party payer perspective.