Profiling ADME attributes of Antibody-Drug Conjugates
Speaker: Cong Wei, PhD, Pfizer
Abstract: Antibody drug conjugate (ADC) is designed for preferential delivery of active pharmacological agent to the cellular target. Measuring conjugated drug of the ADCs is a desirable approach for better assessment of exposure, at the mean time the conjugation of cytotoxic agent to the antibody poses a challenge for precise quantitation of the active moieties. Conventional ligand binding assay is highly dependent on the competency of the antipayload reagents and may not always capture the heterogeneous nature of the ADC, especially when there are active metabolites of the payload. We have established a novel LC/MS strategy for measuring PK of conjugated payload. Depend on the chemistry of linkerpayload and conjugation, intact protein analysis, enzymatic cleavage or bottomup approaches are employed for characterization and quantitative measurement of conjugated active moieties. For cleavable linker based ADC, an enzymatic released protocol was applied to yield the free payload for LC/MS/MS quantitation. For noncleavable linker conjugation, drug loading profile can be analyzed by intact protein LC/MS method. An alternative approach is to identify the signature peptide which contain the conjugation after enzymatic digestion, and followed by LC/MS/MS quantitation. This conjugated payload strategy has being utilized for the development of novel linker-payloads. Overall ADME evaluation of ADC candidates requires multiple platform approach. We will present some of the cases where in vitro assays can be employed to extrapolate efficacy and toxicity profile in preclinical models.
Targeted quantitative proteomics for cancer biomarker validation via high sample throughput N-in-1 uMS
Speaker: Mary Joan Castillo, UCONN
Abstract: Recent advances in mass spectrometry (MS) instrumentation andmethodologies present rapid and reliable discovery of diseaserelevantproteins as biomarkers. Their application in the validation phase, however,is limited by their sample throughput. We leveraged the intrinsic analyte multiplexing capability of MS to sample multiplexing that breaksthrough the sample throughput bottleneck of current MS methods. We termed the new methodology as ultrathroughput MS (uMS), specificallyultrathroughput multiple reaction monitoring MS (uMRM MS), and demonstrated its application through oneexperimentquantitation of multipleserum samples containing common, lowabundanceprostate specific antigen (PSA). The novel bioanalytical platform integrates nonisotopicpeptide derivatization, single peptidelevelenrichment technique, and MRM MS analysis to perform Nin1quantitation of signature peptidesfrom lowabundantproteins. Short peptides with varying sequences and Nterminalcapping groups (termed as peptidyl reagents) were preparedfor uMS high signal yield screening. The opensourcedesign of uMRM MS technology offers facile adaptability and unprecedented potential forimproving the sample throughput in targeted proteomics quantitation using economical, signal enhancing, and structurally customizable reagentsto facilitate MSbasedvalidation of cancer protein biomarkers.