Interaction of Antifungal Drugs with CYP3A- and OATP1B-Mediated Venetoclax Elimination

Strategies for the prophylaxis of invasive fungal diseases in acute myeloid leukemia patients undergoing Bcl-2 inhibitor venetoclax treatment

Patients with acute myeloid leukemia (AML) are at high risk of developing invasive fungal disease (IFD) with high morbidity and attributable mortality, including those who were received Venetoclax treatment. Venetoclax, a new oral Bcl-2 inhibitor, targets tumor cells' ability to induce apoptosis. It is the only one which is approved by Food and Drug Administration (FDA) for treating newly diagnosed AML patients who are 75 years of age or older and are ineligible for intensive induction chemotherapy due to existing comorbidities. It has been shown that venetoclax-based regimens raise the risk of invasive fungal diseases (IFD) for AML patients in clinical practice. Because it can lead to prolonged and profound neutropenia in AML patients, with IFD incidence rates ranging from 5.1 % to 32 %, resulting in higher mortality rates. Because of drug-drug interactions between Venetoclax and partial antifungal agents, to choose anti-fungal prophylaxis and to adjust the dosage of agents rationally for AML patients seems crucial to physicians to those who are undergoing venetoclax-based chemotherapy. Therefore, this review aims to summary the mechanism and characteristic of IFD in AML patients and provide practical clinical suggestions and details for the prophylaxis of IFD in AML patients suffering Venetoclax-based treatment.

Efficacy and safety of hypomethylating agents in the treatment of AML/MDS patients relapsed post allogenetic hematopoietic stem cell transplantation

Introduction

Acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS) constitute myeloid malignancies, and allogeneic hematopoietic stem cell transplantation (allo-HSCT) is considered as a potentially optimal approach for achieving a long term cure. However, post-allo-HSCT relapse remains a leading cause of mortality and therapeutic failure.

Methods

To evaluate the efficacy and safety of combining hypomethylating agents (HMAs) with Bcl-2 inhibitors in the treatment of AML/MDS relapse following allo-HSCT, we retrospectively collected data from 42 patients who experienced relapse between April 2012 and March 2022 at Peking University First Hospital. Among these patients, 21 underwent intensive chemotherapy (IC) alone, while the other 21 received treatment with HMAs after IC treatment, either alone or in combination with the Bcl-2 inhibitor venetoclax (VEN).

Results

The median overall survival (OS) was 9 ± 2.153 months, and the one-year OS rate was 41.5%. The overall response rate (ORR) in the chemotherapy group and the IC+HMAs ± VEN group was 52.38% (11/21) and 76.19% (16/21), respectively, with no significant difference found (P=0.107). Kaplan-Meier analysis revealed a significant difference in OS between the chemotherapy group and the IC+HMAs ± VEN group in our retrospective cohort study (P=0.041, χ2= 4.016). Additionally, a significant difference in overall survival (OS) rates was observed between the two groups for patients categorized as intermediate/high risk (P=0.008). The secondary relapse rate was 45.45% (5/11) in the IC cohort and 25% (4/16) in the IC+HMAs ± VEN group, respectively, with no significant difference identified between the two cohorts (P=0.268). Furthermore, upon assessing the risk of graft-versus-host disease (GvHD), infection, and agranulocytosis, no notable differences were observed with the use of HMAs, suggesting that HMAs did not increase the risk. In the IC+HMAs ± VEN group, 7 patients received VEN in addition to HMAs, and no significant statistical difference was found in OS when comparing patients who received HMAs alone and those who received HMA+VEN (P=0.183), also, a statistically significant difference in OS was noted between the two groups whenaccounting for competing risks (P=0.028).

Conclusions

This retrospective study highlights the efficacy of IC+HMAs ± VEN in treating AML/MDS patients experiencing relapse post allo-HSCT, improving survival rates, especially for those classified as intermediate/high risk, with favorable tolerability.

Remission rate, toxicity and pharmacokinetics of venetoclax-based induction regimens in untreated pediatric acute myeloid leukemia

The efficacy and safety of venetoclax in newly diagnosed pediatric acute myeloid leukemia (AML) are not well-established as they are in adults. Children newly diagnosed with AML were recommended for induction therapy with venetoclax and chemotherapy or hypomethylating agents (HMAs) as per for the ChiCTR1900027146 trial. Venetoclax was administered at a consistent dose of 200 mg/m2/day for 28 days, with adjustments when used concurrently with azoles. The study measured both the remission rates and the safety assessments of venetoclax. We enrolled 45 newly diagnosed pediatric patients with AML. The complete remission rates were 94.7% in the low/middle-risk group and 80.8% in the high-risk group; MRD-negative rates were 52.6% and 38.5% in the low/middle-risk group and high-risk group, respectively. Venetoclax based combination therapy was well tolerated by the majority of patients. The median duration of venetoclax dosing was 18 days (range 9-28), with hematological toxicity and infection being the most common adverse events. Venetoclax-based induction regimens demonstrated a high response rate and safety profile in newly diagnosed pediatric AML cases. This underscores the significance of venetoclax as a viable treatment option for untreated AML, extending beyond its role as salvage therapy for refractory/relapsed AML.

Clinical management of patients diagnosed with acute myeloid leukemia treated with venetoclax in combination with hypomethylating agents after achieving a response: a real-life study

Although there is an approved indication for venetoclax and hypomethylating agents (VenHMA) and its use in different AML settings will be expanded in the following years, the management of the adverse events (AEs) lacks of harmonized algorithms during treatment of these patients. We have studied the incidence of relevant AEs of 43 patients who achieved a response to VenHMA and its management. Median overall survival of our cohort was 19 months. No patients discontinued treatment due to AEs after C3D1, Regarding severe AEs, high rates of grade 4 neutropenia (97.6%) and grade 4 thrombocytopenia (65.1%) were observed. Severe infectious AEs rate was 16%. Due to severe myelotoxicity, most patients required a progressive dose reduction of both venetoclax and hypomethylating agents during follow-up, being 87.8% at C6D1. Transfusional dependence rate was 91% and G-CSF was prescribed to 86% of the patients. Finally, there was not a significant difference in hemoglobin, platelets and absolute neutrophil count after achieving complete response comparing paired samples during follow-up, although cytopenia rate was high during initial follow-up. We conclude that dose reduction of VenHMA after achieving a response in patients diagnosed with AML is required in most patients and essential to avoid prolonged cytopenia-related adverse events and a rapid and standardized method on how to perform it might decrease the AEs rate.

Systematic Evaluation of Tyrosine Kinase Inhibitors as OATP1B1 Substrates Using a Competitive Counterflow Screen

Although the primary elimination pathway for most tyrosine kinase inhibitors (TKI) involves CYP3A4-mediated metabolism, the mechanism by which these agents are brought into hepatocytes remains unclear. In this study, we optimized and validated a competitive counterflow (CCF) assay to examine TKIs as substrates of the hepatic uptake transporter OATP1B1. The CCF method was based on the stimulated efflux of radiolabeled estradiol-17β-glucuronide under steady-state conditions in HEK293 cells engineered to overexpress OATP1B1. Of the 62 approved TKIs examined, 13 agents were identified as putative substrates of OATP1B1, and pazopanib was selected as a representative hit for further validation studies. The transport of pazopanib by OATP1B1 was confirmed by decreased activity of its target VEGFR2 in OATP1B1-overexpressing cells, but not cells lacking OATP1B1, consistent with molecular docking analyses indicating an overlapping binding orientation on OATP1B1 with the known substrate estrone-3-sulfate. In addition, the liver-to-plasma ratio of pazopanib in vivo was decreased in mice with a deficiency of the orthologous transporters, and this was accompanied by diminished pazopanib-induced hepatotoxicity, as determined by changes in the levels of liver transaminases. Our study supports the utility of CCF assays to assess substrate affinity for OATP1B1 within a large set of agents in the class of TKIs and sheds light on the mechanism by which these agents are taken up into hepatocytes in advance of metabolism.

SIGNIFICANCE

Despite the established exposure-pharmacodynamic relationships for many TKIs, the mechanisms underlying the agents' unpredictable pharmacokinetic profiles remain poorly understood. We report here that the disposition of many TKIs depends on hepatic transport by OATP1B1, a process that has toxicologic ramifications for agents that are associated with hepatotoxicity.

Darolutamide does not interfere with OATP-mediated uptake of docetaxel

The addition of darolutamide, an androgen receptor signalling inhibitor, to therapy with docetaxel has recently been approved as a strategy to treat metastatic prostate cancer. OATP1B3 is an SLC transporter that is highly expressed in prostate cancer and is responsible for the accumulation of substrates, including docetaxel, into tumours. Given that darolutamide inhibits OATP1B3 in vitro, we sought to characterise the impact of darolutamide on docetaxel pharmacokinetics. We investigated the influence of darolutamide on OATP1B3 transport using in vitro and in vivo models. We assessed the impact of darolutamide on the tumour accumulation of docetaxel in a patient-derived xenograft (PDX) model and on an OATP1B biomarker in patients. Darolutamide inhibited OATP1B3 in vitro at concentrations higher than the reported Cmax. Consistent with these findings, in vivo studies revealed that darolutamide does not influence the pharmacokinetics of Oatp1b substrates, including docetaxel. Docetaxel accumulation in PDX tumours was not decreased in the presence of darolutamide. Metastatic prostate cancer patients had similar levels of OATP1B biomarkers, regardless of treatment with darolutamide. Consistent with a low potential to inhibit OATP1B3-mediated transport in vitro, darolutamide does not significantly impede the transport of Oatp1b substrates in vivo or in patients. Our findings support combined treatment with docetaxel and darolutamide, as no OATP1B3 transporter based drug-drug interaction was identified.

Pharmacokinetic Boosting of Kinase Inhibitors

(1) Introduction: Pharmacokinetic boosting of kinase inhibitors can be a strategy to enhance drug exposure and to reduce dose and associated treatment costs. Most kinase inhibitors are predominantly metabolized by CYP3A4, enabling boosting using CYP3A4 inhibition. Kinase inhibitors with food enhanced absorption can be boosted using food optimized intake schedules. The aim of this narrative review is to provide answers to the following questions: Which different boosting strategies can be useful in boosting kinase inhibitors? Which kinase inhibitors are potential candidates for either CYP3A4 or food boosting? Which clinical studies on CYP3A4 or food boosting have been published or are ongoing? (2) Methods: PubMed was searched for boosting studies of kinase inhibitors. (3) Results/Discussion: This review describes 13 studies on exposure boosting of kinase inhibitors. Boosting strategies included cobicistat, ritonavir, itraconazole, ketoconazole, posaconazole, grapefruit juice and food. Clinical trial design for conducting pharmacokinetic boosting trials and risk management is discussed. (4) Conclusion: Pharmacokinetic boosting of kinase inhibitors is a promising, rapidly evolving and already partly proven strategy to increase drug exposure and to potentially reduce treatment costs. Therapeutic drug monitoring can be of added value in guiding boosted regimens.

Machine Learning Models Identify New Inhibitors for Human OATP1B1

The uptake transporter OATP1B1 (SLC01B1) is largely localized to the sinusoidal membrane of hepatocytes and is a known victim of unwanted drug-drug interactions. Computational models are useful for identifying potential substrates and/or inhibitors of clinically relevant transporters. Our goal was to generate OATP1B1 in vitro inhibition data for [3H] estrone-3-sulfate (E3S) transport in CHO cells and use it to build machine learning models to facilitate a comparison of seven different classification models (Deep learning, Adaboosted decision trees, Bernoulli naïve bayes, k-nearest neighbors (knn), random forest, support vector classifier (SVC), logistic regression (lreg), and XGBoost (xgb)] using ECFP6 fingerprints to perform 5-fold, nested cross validation. In addition, we compared models using 3D pharmacophores, simple chemical descriptors alone or plus ECFP6, as well as ECFP4 and ECFP8 fingerprints. Several machine learning algorithms (SVC, lreg, xgb, and knn) had excellent nested cross validation statistics, particularly for accuracy, AUC, and specificity. An external test set containing 207 unique compounds not in the training set demonstrated that at every threshold SVC outperformed the other algorithms based on a rank normalized score. A prospective validation test set was chosen using prediction scores from the SVC models with ECFP fingerprints and were tested in vitro with 15 of 19 compounds (84% accuracy) predicted as active (≥20% inhibition) showed inhibition. Of these compounds, six (abamectin, asiaticoside, berbamine, doramectin, mobocertinib, and umbralisib) appear to be novel inhibitors of OATP1B1 not previously reported. These validated machine learning models can now be used to make predictions for drug-drug interactions for human OATP1B1 alongside other machine learning models for important drug transporters in our MegaTrans software.

The Growing Role of the BH3 Mimetic Drug Venetoclax in the Therapy of Acute Myeloid Leukemia

Despite recent progress, acute myeloid leukemia (AML) remains a disease associated with poor prognosis, particularly in older AML patients unfit to tolerate intensive chemotherapy treatment. The development and introduction in the therapy of Venetoclax (VEN), a potent BH3 mimetic targeting the antiapoptotic protein BCL-2, inducing apoptosis of leukemic cells, has shown to be a promising treatment for newly diagnosed, relapsed, and refractory AML patients ineligible for induction chemotherapy. Combination treatments using Ventoclax and a hypomethylating agent (azacitidine or decitabine) or low-intensity chemotherapy have shown in newly diagnosed patients variable response rates, with highly responsive patients with NPM1, IDH1-IDH2, TET2, and RUNX1 mutations and with scarcely responsive patients with FLT3, TP53 and ASXL1 mutations, complex karyotypes, and secondary AMLs. Patients with refractory/relapsing disease are less responsive to Venetoclax-based regimens. However, in the majority of patients, the responses have only a limited duration, and the development of resistance is frequently observed. Therefore, understanding the resistance mechanisms is crucial for developing new strategies and identifying rational drug combination regimens. In this context, two strategies seem to be promising: (i) triplet therapies based on the combined administration of Venetoclax, a hypomethylating agent (or low-dose chemotherapy), and an agent targeting a specific genetic alteration of leukemic cells (i.e., FLT3 inhibitors in FLT3-mutated AMLs) or an altered signaling pathway; (ii) combination therapies based on the administration of two BH3 mimetics (i.e., BCL-2 +MCL-1 mimetics) and a hypomethylating agent.

Determination of the endogenous OATP1B biomarkers glycochenodeoxycholate-3-sulfate and chenodeoxycholate-24-glucuronide in human and mouse plasma by a validated UHPLC-MS/MS method

Glycochenodeoxycholate-3-sulfate (GCDCA-S) and chenodeoxycholate-24-glucuronide (CDCA-24G) are bile acid metabolites that potentially serve as endogenous biomarkers for drug-drug interactions mediated by the hepatic uptake transporters OATP1B1 and OATP1B3. We developed and validated a novel UHPLC-MS/MS method for the quantitative determination of GCDCA-S and CDCA-24G in mouse and human plasma with a lower limit of quantitation of 0.5 ng/mL. Chromatographic separation was achieved on an Accucore aQ column (50 mm × 2.1 mm, dp = 2.6 μm) maintained at 20 °C and a gradient mobile phase comprising 2 mM ammonium acetate in water and methanol. The extraction recoveries of GCDCA-S and CDCA-24G were >80 %, and linear (r2 > 0.99) calibration curves ranged 0.5-100 ng/mL (CDCA-24G and GCDCA-S in mouse plasma) or 0.5-1000 ng/mL (GCDCA-S in mouse plasma). Values for precision (CV < 11.6 %) and accuracy bias (10.9 %) of analyte-spiked quality control samples verified that water was an acceptable matrix to prepare calibrators. This method was successfully applied to establish baseline activity of OATP1B1/OATP1B3 in humans and mice and establish the in vivo effects of OATP1B1/OATP1B3 inhibitors rifampin and micafungin.

Itraconazole-Induced Increases in Gilteritinib Exposure Are Mediated by CYP3A and OATP1B

Gilteritinib, an FDA-approved tyrosine kinase inhibitor approved for the treatment of relapsed/refractory FLT3-mutated acute myeloid leukemia, is primarily eliminated via CYP3A4-mediated metabolism, a pathway that is sensitive to the co-administration of known CYP3A4 inhibitors, such as itraconazole. However, the precise mechanism by which itraconazole and other CYP3A-modulating drugs affect the absorption and disposition of gilteritinib remains unclear. In the present investigation, we demonstrate that pretreatment with itraconazole is associated with a significant increase in the systemic exposure to gilteritinib in mice, recapitulating the observed clinical drug–drug interaction. However, the plasma levels of gilteritinib were only modestly increased in CYP3A-deficient mice and not further influenced by itraconazole. Ensuing in vitro and in vivo studies revealed that gilteritinib is a transported substrate of OATP1B-type transporters, that gilteritinib exposure is increased in mice with OATP1B2 deficiency, and that the ability of itraconazole to inhibit OATP1B-type transport in vivo is contingent on its metabolism by CYP3A isoforms. These findings provide new insight into the pharmacokinetic properties of gilteritinib and into the molecular mechanisms underlying drug–drug interactions with itraconazole.

Safe administration and pharmacokinetic monitoring of crushed venetoclax tablets with posaconazole and clarithromycin via percutaneous endoscopic gastrostomy tube in a patient with acute myeloid leukemia

PURPOSE

Leukemic stem cells in acute myeloid leukemia (AML) express high B cell lymphoma 2 (BCL2) levels, which contribute to leukemic cell survival and resistance to therapy. Venetoclax-a BCL-2 inhibitor-is indicated for the treatment of AML, which may also target leukemic stem cells; however, it is only available as a tablet. There are no reports of venetoclax use in patients who cannot take oral drugs; therefore, the efficacy, safety, and pharmacokinetics (PK) of venetoclax administered through a gastrostomy tube is unknown.

CASE PRESENTATION

We report, for the first time, a case of relapsed Japanese AML patient treated with crushed venetoclax tablets through a percutaneous endoscopic gastrostomy (PEG) tube because of esophageal stricture due to complications of stem cell transplantation. The patient was also taking posaconazole and clarithromycin concomitantly. We evaluated the plasma concentrations of venetoclax administered through a PEG tube. Time to maximum concentration, maximum plasma concentration, and the area under the plasma concentration-time curve were similar to the previously reported PK parameters after oral administration of intact venetoclax tablets in Japanese patients with AML. The clinical course passed safely without the occurrence of unexpected adverse events during the administration of crushed venetoclax tablets in combination with azacitidine.

CONCLUSIONS

The PK parameters of the crushed administered venetoclax via PEG tube was similar to the previously reported PK parameters of the orally administered venetoclax. Therefore, administration of crushed venetoclax tablets through a PEG tube could be an alternate route for patients who have difficulty with oral administration.