LC-Q-TOF-MS driven identification of potential degradation impurities of venetoclax, mechanistic explanation on degradation pathway and establishment of a quantitative analytical assay method

Dhruvisha Pokar,Pinaki Sengupta,Amit Kumar Sahu

doi:10.1186/s40543-020-00252-4

Abstract

Venetoclax is a selective orally active Bcl-2 protein inhibitor very recently approved by USFDA to treat chronic lymphocytic leukemia and other hematological malignancies. Postmarketing surveillance of any drug depends on its acceptability based on risk to benefit ratio. When risk outweighs the benefits, withdrawal of an already marketed drug is warranted. Presence of impurity is the primary cause of increased risk in a drug substance or drug product. With the discovery of newer molecules, it is of great importance to establish advanced analytical techniques for quantification of the drugs as well as their related impurities to address the prospective regulatory queries even if it is already in the market. In this study, a quantitative analytical assay method has been developed and validated for quantification of venetoclax in presence of its degradation impurities. A stress study was performed to examine the stability of the drug in hydrolytic, oxidative, thermolytic and photolytic environments. Venetoclax was found to be prone to degradation in acidic hydrolytic and oxidative stress conditions. Three new degradation impurities have been identified and characterized with the help of LC-Q-TOF-MS with accurate mass measurement and their putative structures have been proposed. Furthermore, for the first time, a possible degradation pathway has been established with mechanistic explanation. Moreover, the analytical method developed in this study will be of immense help for routine analysis of quality control and stability study samples of venetoclax in industry and research laboratories.

Highlights

Venetoclax (VEN) is a selective, novel, and orally active B-cell lymphoma 2 (Bcl-2) protein inhibitor very recently approved by the United States Food and Drug Administration (USFDA) to treat chronic lymphocytic leukemia and other hematological malignancies (Mato et al 2018).Chemically VEN belongs to biaryl acylsulfonamide class of anticancer molecule indicated for the treatment in adult cancer patients with 17p deletion or tumor suppression gene TP53 mutation or chemo-immunotherapy resistance
In this study, a quantitative high performance liquid chromatography (HPLC) assay method has been established for quantification of VEN in presence of their degradation impurities
Stress study of VEN was performed by using different ICH recommended stresses including hydrolysis, oxidation, thermolysis and photolysis

Summary

Introduction

Venetoclax (VEN) is a selective, novel, and orally active B-cell lymphoma 2 (Bcl-2) protein inhibitor very recently approved by the United States Food and Drug Administration (USFDA) to treat chronic lymphocytic leukemia and other hematological malignancies (Mato et al 2018).Chemically VEN belongs to biaryl acylsulfonamide class of anticancer molecule indicated for the treatment in adult cancer patients with 17p deletion (chromosome abnormality) or tumor suppression gene TP53 mutation or chemo-immunotherapy resistance. Forced degradation is a strategy employed to cause stress decomposition of a molecule to generate degradation impurities for their subsequent identification It is carried out at conditions more severe than accelerated conditions, which further help in evaluating the stability of a molecule (Inturi et al 2018; Blessy et al 2014). Assessment of degradation impurities through stress testing is an obvious requirement in a drug development program that helps in understanding the degradation behavior of a drug (Brümmer 2011; Sengupta et al 2018). It provides physicochemical and stereochemical stability of bulk drug and its formulation. Among all the sophisticated techniques chromatographic retention assisted mass spectrometry including Q-TOF is considered an excellent tool in characterization of unknown drug-related impurities with high selectivity and sensitivity (Watkins 2020; Chang et al 2018; Kitagawa 2019)

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