LC-MS multi-attribute method for characterization of biologics

(mAbs), are complex protein molecules produced from mammalian tissue culture cells through recombinant DNA technology. As a result of naturally-occurring molecular heterogeneity as well as chemical and enzymatic modifications during manufacture, process, and storage, there are many product quality attributes (PQAs) presenting in therapeutic proteins. These PQAs can potentially include: product-related structural heterogeneity related to glycosylation profile, disulfide bond pattern, and higher order structure; product-related degradants and impurities, such as deamidation, oxidation, sequence variants; and process-related impurities and residuals, such as host cell protein (HCP), host cell DNA, and residual protein A [1]. Regulatory agencies have recently recommended a Quality by Design (QbD) approach for the manufacturing of therapeutic molecules [2-5], which requires in-depth understanding of these PQAs at the molecular level to ensure that the drug products meet the desired safety and efficacy profiles [6]. The QbD guidelines require development of a quality target product profile (QTPP) that identifies critical quality attributes (CQAs) and implementation of control strategies to ensure that the QTPP is achieved. QTPP is a prospective summary of the quality characteristics of a drug product to be achieved to ensure the desired quality, safety and efficacy [2]. QTPP describes the design criteria for the product and forms the basis for determination of the CQAs, critical process parameters (CPPs), and control strategy. A CQA is a physical, chemical, biological, or microbiological property or characteristic that should be within an appropriate limit, range, or distribution to ensure the desired product quality [2]. A CQA is identified based on the severity of harm to a patient resulting from failure to meet that quality attribute. Analytical methods to identify and quantify these PQAs, especially CQAs, are essential for the development of QTPP and implementation of control strategies. Conventionally, a panel of analytical techniques such as size-exclusion chromatography (SEC), ion-exchange chromatography (IEX), hydrophobic-interaction chromatography (HIC), or capillary electrophoresis (CE) is typically used to monitor product quality consistency as well as product variants and impurities at the intact protein level [7-9]. Although these chromatographic and electrophoretic methods widely are used as release assays for biologics [10], they cannot directly monitor biologically relevant PQAs at the molecular level, which does not align with QbD principles. The complexity of biologics attributes and the implementation of QbD strategies demand a multi-attribute method (MAM) that can monitor multiple biologics PQAs at the molecular level in a single assay. Coupling liquid chromatography (LC) to high resolution and high accuracy mass spectrometry (MS) techniques, LC-MS based peptide mapping has become a MAM approach that can identify and quantify multiple attributes JOURNAL OF APPLIED BIOANALYSIS, April 2017, p. 21-25. http://dx.doi.org/10.17145/jab.17.003 (ISSN 2405-710X) Vol. 3, No. 2