Venetoclax in combination with azacitidine in Japanese patients with acute myeloid leukaemia: phase 1 trial findings

Development and validation of a sensitive and fast bioanalytical LC-MS/MS assay for the quantitation of venetoclax and azacitidine in Rat Plasma: Application to pharmacokinetic study

The combination of venetoclax plus azacitidine (VTX-AZA) is FDA-approved to treat patients with acute myeloid leukemia (AML) aged ≥75 years and has become the standard of care for AML patients. However, the literature has not reported an analytical method for determining VTX-AZA in plasma samples. Therefore, developing an accurate and sensitive bioanalytical assay to quantify VTX-AZA in plasma is important. For the first time, this study describes the development of a new liquid chromatography-tandem mass spectrometry method (LC-MS/MS) for the simultaneous determination of VTX and AZC in plasma samples with its application to pharmacokinetic study in rats. The assay employs repaglinide (RPG) as an internal standard. The chromatographic separations of VTX, AZC, and RPG are achieved within 2.5 min at 25 °C on an Eclipse plus C18 column (100 mm × 2.1 mm, 1.8 μm) and an isocratic mobile phase consisted of water with 0.1 % formic acid and acetonitrile (50:50, v/v, pH 3.2) at a flow rate of 0.30 mL/min. VTX and AZC have been extracted from rat plasma using the solid-phase extraction (SPE) procedure without interference from plasma endogenous. The FDA guidelines were followed in the validation of the developed assay, and linearity in rat plasma was observed for AZC and VTX, respectively, ranging from 5 to 3000 and 5-1000 ng/mL, with r ≥ 0.998. The lower limits of detection (LLOD) were 2 ng/mL for both drugs. In addition, the inter-day and intra-day accuracy were 0.8-6.6 % and 2.2-5.7 %; the inter-day and intra-day precision were 3-6.6 % and 1.5-7.1 %, respectively. The validated assay was effectively used in a pharmacokinetic investigation including the simultaneous oral administration of 40 mg/kg of AZA and 100 mg/kg of VTX to rats. The maximum plasma concentration (Cmax) for AZC and VTX was 794 ± 99.6 ng/mL and 641 ± 96.9 ng/mL achieved at 0.5 ± 0.03 h and 6 ± 0.05 h, respectively. The AUC0-∞ for AZC and VTX was 1253 ± 252.6 and 4881 ± 745.4 ng/mL.h; respectively.

Individualized medication of venetoclax based on therapeutic drug monitoring in Chinese acute myeloid leukemia patients using an HPLC method

OBJECTIVE

The aim of this study was to establish a simple and sensitive high-performance liquid chromatography method for therapeutic drug monitoring of venetoclax (VEN) and optimize regimens.

METHODS

The analysis required the extraction of a 50 μl plasma sample and the precipitation of proteins using acetonitrile extraction. The chromatographic method employed a mobile phase of acetonitrile: 0.5% KH 2 PO 4 (pH 3.5) (60/40, v/v) on a Diamond C 18 (4.6 mm × 250 mm, 5 μm) column at a flow rate of 1.0 ml/min. The quantitative method was validated based on standards described in 'Bioanalytical Method Validation: Guidance for Industry' published by the US Food and Drug Administration (FDA).

RESULTS

The calibration curve was linear ( R2  = 0.9998) over the range of 75-4800 ng/ml, with limits of quantification of 25 ng/ml. The coefficients of intraday and interday validation, specificity, recovery, and stability all met the criteria of FDA guidance. The method was successfully applied to analyze VEN concentrations in 30 cases of acute myeloid leukemia patients. The peak concentration ( Cmax ) was 1881.19 ± 756.61 ng/ml, while the trough concentration ( Cmin ) was 1212.69 ± 767.92 ng/ml in acute myeloid leukemia patients.

CONCLUSION

Our study establishes a simple, precise, and sensitive high-performance liquid chromatography method for monitoring VEN and confirms its applicability for therapeutic drug monitoring of VEN in hematological cancers.

Overexposure to venetoclax is associated with prolonged-duration of neutropenia during venetoclax and azacitidine therapy in Japanese patients with acute myeloid leukemia

PURPOSE

An observational study was conducted to evaluate the pharmacokinetics of venetoclax and its impact on the efficacy and safety for Japanese patients with acute myeloid leukemia (AML) treated with venetoclax and azacitidine therapy.

METHODS

The association between the plasma concentration, after the first cycle of azacitidine and venetoclax therapy, and the efficacy and safety was evaluated in 33 patients with untreated or relapsed/refractory AML.

RESULTS

Full dose of venetoclax was administered to all patients. Venetoclax treatment was 28 day long in 82% of patients; the relative dose intensity of azacitidine was 82%. Trough concentration was significantly higher among patients with complete remission (CR) and CR with incomplete hematologic recovery (CRi) than those with the morphologic leukemia-free state and partial remission, and no response groups (P = 0.01). Median duration of grade 3 neutropenia was 28 days (range 8-46 days). Area under the concentration-time curve (AUC0-24) was significantly higher among patients with protracted grade 3 neutropenia (≥ 28 days) than those with a shorter duration (< 28 days) (P = 0.03); multivariate analysis revealed that a higher AUC0-24 was a significant predictor of a longer duration of neutropenia (odds ratio 54.3, P = 0.007).

CONCLUSION

Plasma concentrations of venetoclax were variable in Japanese patients with AML. Higher plasma concentrations were associated with CR/CRi and protracted grade 3 neutropenia. Therefore, it is essential to adjust the duration of venetoclax administration based on individual pharmacokinetic data to limit total drug exposure, reduce severe neutropenia, and achieve higher efficacy.

Plasma Venetoclax Concentrations in Patients with Acute Myeloid Leukemia Treated with CYP3A4 Inhibitors

Venetoclax (VEN) is used in patients with acute myeloid leukemia (AML) and is primarily metabolized by CYP3A4, a major drug-metabolizing enzyme. Patients with AML simultaneously administered VEN and CYP3A4 inhibitors require a more appropriate management of drug-drug interactions (DDIs). Here, we report two cases of patients with AML (54-year-old man and 22-year-old woman) administrated VEN and CYP3A4 inhibitors, such as posaconazole, cyclosporine, or danazol. In the first case, we evaluated the appropriateness of timing for adjusting VEN dosage subsequent to the cessation of posaconazole. Consequently, modifying the VEN dosage in conjunction with the cessation of Posaconazole simultaneously may result in elevated plasma VEN levels. In the second case, plasma VEN concentrations were markedly elevated when co-administered with several CYP3A4 inhibitors. Additionally, in vitro assays were conducted for reverse translational studies to analyze CYP3A4 inhibition. CYP3A4 inhibition by combinatorial administration of cyclosporine A and danazol was demonstrated in vitro, which potentially explains the increasing plasma VEN concentrations observed in clinical settings. Although the acquisition of therapeutic effects is a major priority for patients, frequent therapeutic drug monitoring and dosage adjustments considering DDIs would be important factors in chemotherapy.

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.

Determination of Venetoclax Concentration in Plasma Using High-Performance Liquid Chromatography

Venetoclax is an oral B-cell lymphoma-2 protein inhibitor. It is a key drug for the treatment of chronic lymphocytic leukemia and acute myeloid leukemia. However, venetoclax is administered at a fixed dose, irrespective of body surface area or weight. Furthermore, the plasma concentration of venetoclax varies widely between individuals and is influenced by diet. Therefore, individualized dosing using therapeutic drug monitoring (TDM) may help to optimize treatment in clinical practice. In this study, we aimed to develop a simple method to determine venetoclax concentrations in plasma. The analysis required the extraction of a 50-μL plasma sample and precipitation of proteins using acetonitrile extraction. Venetoclax and the internal standard (12.5-μg/mL ibrutinib) were separated by high-performance liquid chromatography (HPLC). The calibration curve was linear over the plasma venetoclax concentration range 0.25-10 μg/mL with a coefficient of determination (r2) of 0.9999. The coefficients of intra-day and inter-day validation were 0.8-4.1% and 1.3-3.3%, respectively. The assay accuracy was -2.8 to 1.6%, and the recovery was >97.2%. These results demonstrate a very simple, novel and sensitive HPLC-UV-based method for determining the concentration of plasma venetoclax, and confirm its applicability to the TDM of venetoclax in a clinical setting.

Venetoclax plus azacitidine in Japanese patients with untreated acute myeloid leukemia ineligible for intensive chemotherapy

Background

The phase 3 VIALE-A trial (NCT02993523) reported that venetoclax-azacitidine significantly prolonged overall survival compared with placebo-azacitidine in patients with newly diagnosed acute myeloid leukemia ineligible for intensive chemotherapy. Herein, efficacy and safety of venetoclax-azacitidine are analyzed in the Japanese subgroup of VIALE-A patients.

Methods

Eligible Japanese patients were randomized 2:1 to venetoclax-azacitidine (N = 24) or placebo-azacitidine (N = 13). Primary endpoints for Japan were overall survival and complete response (CR) + CR with incomplete hematologic recovery (CRi). Venetoclax (target dose 400 mg) was given orally once daily. Azacitidine (75 mg/m²) was administered subcutaneously or intravenously on Days 1–7 of each 28-day cycle.

Results

Median follow-up was 16.3 months (range, 1.0–20.3). Median overall survival was not reached with venetoclax-azacitidine (hazard ratio 0.409 and 95% confidence interval: 0.151, 1.109); overall survival estimate was higher with venetoclax-azacitidine than placebo-azacitidine at 12 (67 and 46%) and 18 months (57 and 31%), respectively. CR and CRi rates were 67% with venetoclax-azacitidine and 15% with placebo-azacitidine. Most common any-grade adverse events were febrile neutropenia (79 and 39%), thrombocytopenia (54 and 77%), constipation (54 and 54%) and decreased appetite (54 and 38%) in the venetoclax-azacitidine and placebo-azacitidine arms, respectively. Only 1 patient in the venetoclax-azacitidine arm, and no patients in the placebo-azacitidine arm, had grade 4 febrile neutropenia that led to treatment discontinuation.

Conclusions

This Japanese subgroup analysis of VIALE-A demonstrates comparable safety and efficacy outcomes compared with the global study and supports venetoclax-azacitidine as first-line standard-of-care for Japanese treatment-naive patients with acute myeloid leukemia who are ineligible for intensive chemotherapy.