Combined Falling Drop/Open Port Sampling Interface System for Automated Flow Injection Mass Spectrometry.

The aim of this work was to demonstrate and to evaluate the analytical performance of a combined falling drop/open port sampling interface (OPSI) system as a simple noncontact, no-carryover, automated system for flow injection analysis with mass spectrometry. The falling sample drops were introduced into the OPSI using a widely available autosampler platform utilizing low cost disposable pipet tips and conventional disposable microtiter well plates. The volume of the drops that fell onto the OPSI was in the 7-15 µL range with an injected sample volume of several hundred nanoliters. Sample drop height, positioning of the internal capillary on the sampling end of the probe, and carrier solvent flow rate were optimized for maximum signal. Sample throughput, signal reproducibility, matrix effects, and quantitative analysis capability of the system were established using the drug molecule propranolol and its isotope labeled internal standard in water, unprocessed river water and two commercially available buffer matrices. A sample-to-sample throughput of ∼45 s with a ∼4.5 s base-to-base flow injection peak profile was obtained in these experiments. In addition, quantitation with minimally processed rat plasma samples was demonstrated with three different statin drugs (atorvastatin, rosuvastatin, and fluvastatin). Direct characterization capability of unprocessed samples was demonstrated by the analysis of neat vegetable oils. Employing the autosampler system for spatially resolved liquid extraction surface sampling exemplified by the analysis of propranolol and its hydroxypropranolol glucuronide phase II metabolites from a rat thin tissue section was also illustrated.

Compound Property Optimization in Drug Discovery Using Quantitative Surface Sampling Micro Liquid Chromatography with Tandem Mass Spectrometry.

Surface sampling micro liquid chromatography tandem mass spectrometry (SSµLC-MS/MS) was explored as a quantitative tissue distribution technique for probing compound properties in drug discovery. A method was developed for creating standard curves using surrogate tissue sections from blank tissue homogenate spiked with compounds. The resulting standard curves showed good linearity and high sensitivity. The accuracy and precision of standards met acceptance criteria of ±30%. A new approach was proposed based on an experimental and mathematical method for tissue extraction efficiency evaluation by means of consecutively sampling a location on tissue twice by SSµLC-MS/MS. The observed extraction efficiency ranged from 69% to 82% with acceptable variation for the test compounds. Good agreement in extraction efficiency was observed between surrogate tissue sections and incurred tissue sections. This method was successfully applied to two case studies in which tissue distribution was instrumental in advancing project teams' understanding of compound properties.

An integrated outsourcing practice of nonclinical LC-MS bioanalysis and toxicokinetics at Novartis small molecule drug development.

With decommissioning of internal regulated bioanalytical (BA) and toxicokinetic (TK) capabilities, Novartis has relied on external service providers (ESPs) for all nonclinical LC-MS BA and majority of the associated TK work since 2017. This paper outlines an integrated outsourcing practice of the Novartis nonclinical LC-MS BA/TK group, which covers the roles and responsibilities of Novartis nonclinical LC-MS BA/TK expert scientific monitors, selection of ESPs for Novartis nonclinical LC-MS BA/TK studies, qualification of BA/TK ESPs, study conduct and completion, ESP oversight and evaluation, issue mitigation, and future perspectives.

Bioanalytical Challenges in Support of Complex Modalities of Antibody-Based Therapeutics.

Antibody-based therapeutic classes are evolving from monoclonal antibodies to antibody derivatives with complex structures to achieve advanced therapeutic effect. These antibody derivatives may contain multiple functional domains and are often vulnerable to in vivo biotransformation. Understanding the pharmacokinetics of these antibody derivatives requires a sophisticated bioanalytical approach to carefully characterize the whole drug and each functional domain with respect to quantity, functionality enabled by biotransformation, and corresponding immune responses. Ligand binding assays and liquid chromatography-mass spectrometry assays are predominantly used in bioanalytical support of monoclonal antibodies and are continuously used for antibody derivatives such as antibody drug conjugate and bispecific antibodies. However, they become increasingly cumbersome in coping with increased complexity of drug modality and associated biotransformation. In this mini-review, we examined the current pharmacokinetic assays in the literature for antibody drug conjugate and bispecific antibodies, and presented our view of promising bioanalytical technologies to address the distinct bioanalytical needs of complex modalities.

Dixon's Q-test and Student's t-test to assess analog internal standard response in nonregulated LC-MS/MS bioanalysis.

Aim: In bioanalytical assays, analyte response is normalized to an internal standard response. When the internal standard works well, it compensates for processing and detection variability. However, in case the internal standard introduces additional variability, due to addition errors or other issues, scientists need to identify this. Results: A new method, using a Q-test for outliers and a t-test to compare internal standard response from different sample types, is applied to 15 cases. The results show that the Q-test/t-test, which uses confidence level rather than arbitrary cut-points, is more discerning of deviations compared with widely used methods. Conclusion: This work may improve the quality of and rationale for the internal standard response monitoring method.

IQ consortium perspective: complementary LBA and LC-MS in protein therapeutics bioanalysis and biotransformation assessment.

Increasingly diverse large molecule modalities have driven the need for complex bioanalysis and biotransformation assessment involving both traditional ligand-binding assays (LBA) and more recent hybrid immunoaffinity LC-MS platforms. Given the scientific expertise in LBA and LC-MS typically resides in different functions within the industry, this has presented operational challenges for an integrated approach for bioanalysis and biotransformation assessment. Encouragingly, over time, the industry has recognized the complementary value of the two platforms. This has not been an easy transition as organizational structures vary widely within the industry. However, there are tremendous benefits in adopting fully integrated strategies for biopharma. This IQ consortium paper presents current perspectives across the biopharma industry. It highlights the technical and operational challenges in current large molecule bioanalysis, the value of collaborations across LBA and LC-MS, and scientific expertise for fully integrated strategies for bioanalysis and biotransformation.