BACKGROUND: Midostaurin is a multikinase inhibitor approved for the treatment of adult patients with newly diagnosed FMS-like tyrosine kinase 3 mutated (FLT3m) acute myeloid leukemia (AML). Azole antifungal medications are commonly used in AML and are known to interact with anti-cancer drugs such as midostaurin through the CYP3A pathway. However, there are no midostaurin related dose modifications recommended with strong CYP3A inhibitors.
METHODS: We retrospectively reviewed 40 patients between 2017-2022 and compared efficacy and safety outcomes in patients who received azole antifungals concurrently to those who did not receive an azole or received it sequentially to midostaurin for treatment of FLT3m AML.
RESULTS: Median age of both groups was approximately 55 years and 70% of patients harbored FLT-3 internal tandem duplication mutations. Most patients in the concurrent arm were on either posaconazole (33%) or isavuconazole (50%) for antifungal prophylaxis and micafungin (72%) for the sequential/no azole arm. Overall CR/CRi rate with concurrent versus sequential/no azole were 72% and 77%, and non-hematologic grade 3 toxicities were 22% and 40% (p = 0.21), respectively. Rates of dose reductions (6% vs. 0%, p = 0.26) and held doses (17% vs. 14%, p = 0.79) were not different between concurrent and sequential/no azole. There were no differences in the rates of new fungal infection during induction between the two groups.
CONCLUSIONS: Azoles given concurrently or sequentially with midostaurin were found to be equally safe and effective in the treatment of newly diagnosed FLT3 AML. Additional confirmatory studies are needed due to our limited sample size.

Precision medicine has revolutionized modern cancer therapeutic management by targeting specific molecular aberrations responsible for the onset and progression of tumorigenesis. ROS proto-oncogene 1 (ROS1) is a receptor tyrosine kinase (RTK) that can induce tumorigenesis through various signaling pathways, such as cell proliferation, survival, migration, and metastasis. It has emerged as a promising therapeutic target in various cancer types. However, there is very limited availability of specific ROS1 inhibitors for therapeutic purposes. Exploring repurposed drugs for rapid and effective treatment is a useful approach. In this study, we utilized an integrated approach of virtual screening and molecular dynamics (MD) simulations of repurposing existing drugs for ROS1 kinase inhibition. Using a curated library of 3648 FDA-approved drugs, virtual screening identified drugs capable of binding to ROS1 kinase domain. The results unveil two hits, Midostaurin and Alectinib with favorable binding profiles and stable interactions with the active site residues of ROS1. These hits were subjected to stability assessment through all-atom MD simulations for 200 ns. MD results showed that Midostaurin and Alectinib were stable with ROS1. Taken together, the study showed a rational framework for the selection of repurposed Midostaurin and Alectinib with ROS1 inhibitory potential for therapeutic management after further validation.

OBJECTIVE: Midostaurin, approved for FLT3-mutated acute myeloid leukemia and advanced systemic mastocytosis, is mainly metabolized by cytochrome P450 (CYP) 3A4. Midostaurin exhibited potential inhibitory effects on P-glycoprotein (P-gp), breast cancer resistance protein (BCRP), organic anion-transporting polyprotein 1B1, and CYP2D6 in in vitro studies. This study investigated the pharmacokinetic (PK) effects of midostaurin on P-gp (digoxin), BCRP (rosuvastatin) and CYP2D6 (dextromethorphan) substrates in healthy adults.
METHODS: This was an open-label, single-sequence, phase I clinical study evaluating the effect of single-dose midostaurin (100 mg) on the PK of digoxin and rosuvastatin (Arm 1), and dextromethorphan (Arm 2). Participants were followed up for safety 30 days after last dose. In addition, the effect of midostaurin on the PK of dextromethorphan metabolite (dextrorphan) was assessed in participants with functional CYP2D6 genes in Arm 2.
RESULTS: The effect of midostaurin on digoxin was minor and resulted in total exposure (AUC) and peak plasma concentration (Cmax) that were only 20% higher. The effect on rosuvastatin was mild and led to an increase in AUCs of approximately 37-48% and of 100% in Cmax. There was no increase in the primary PK parameters (AUCs and Cmax) of dextromethorphan in the presence of midostaurin. The study treatments were very well tolerated with no occurance of severe adverse events (AEs), AEs of grade ≥ 2, or deaths.
CONCLUSIONS: Midostaurin showed only a minor inhibitory effect on P-gp, a mild inhibitory effect on BCRP, and no inhibitory effect on CYP2D6. Study treatments were well tolerated in healthy adults.

Systemic mastocytosis (SM) is a rare type of myeloproliferative neoplasm characterized by abnormal proliferation and infiltration of different tissue by clonal mast cells. The uncontrolled proliferation and activation of mast cells trigger the release of vasoactive and inflammatory mediators, resulting in a cascade of systemic symptoms. Around 95% of SM arise from a gain-of-function mutation at the KIT gene, specifically at codon 816, which highlights its essential role in SM and makes it an attractive target for therapy. Although KIT-negative SM is exceptionally rare, the increased number of cases documented in the literature makes it an intriguing dimension of this disorder. The reported clinical manifestations of KIT-negative SM are widely variable, but many are similar to KIT-positive SM. KIT-targeted therapeutic options have been a game-changer in KIT-positive SM, however their role in KIT-negative SM remains controversial. This report aimed to further understand KIT-negative SM by presenting two cases of KIT-negative SM, one of which was responsive to KIT-targeted therapy, and analyzing reported cases in the existing literature.

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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.

Early induction response assessment with day-21 bone marrow (D21-BM) is commonly performed in patients with FLT3-mutated acute myeloid leukaemia (AML), where detection of residual leukaemia (RL; blasts ≥5%) typically results in the administration of a second induction course. However, whether D21-BM results predict for RL at the end of first induction has not been systematically assessed. This study evaluates the predictive role of D21-BM morphology in detecting RL following first induction. Between August 2018 and March 2022, all patients with FLT3-AML receiving 7+3 plus midostaurin, with D21-BM performed, were identified. Correlation between D21-BM morphology vs D21-BM ancillary flow/molecular results, as well as vs D28-BM end of first induction response, were retrospectively reviewed. Subsequently, D21-BMs were subjected to anonymised morphological re-assessments by independent haematopathologists (total in triplicate per patient). Of nine patients included in this study, three (33%) were designated to have RL at D21-BM, all of whom entered complete remission at D28-BM. Furthermore, only low-level measurable residual disease was detected in all three cases by flow or molecular methods at D21-BM, hence none proceeded to a second induction. Independent re-evaluations of these cases failed to correctly reassign D21-BM responses, yielding a final false positive rate of 33%. In summary, based on morphology alone, D21-BM assessment following 7+3 intensive induction plus midostaurin for FLT3-AML incorrectly designates RL in some patients; thus correlating with associated flow and molecular results is essential before concluding RL following first induction. Where remission status is unclear, repeat D28-BMs should be performed.

Aneurysmal fibrous histiocytoma (AFH) is a rare variant of cutaneous fibrous histiocytoma, with low malignant potential and infrequent metastatic progression. We present the case of a 19-year-old female with a large AFH of the neck metastatic to soft tissue and treated with radiation therapy and molecularly targeted therapy. To our knowledge, this is the first report describing either radiation therapy and palliation or the use of targeted therapy in this uncommon malignancy and can provide insight into future therapeutic strategies.

OBJECTIVE: 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.
CONCLUSIONS: 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.

OBJECTIVE: 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.
CONCLUSIONS: 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.