Antibody-drug conjugates (ADCs) constitute a promising class of targeted oncology therapeutics that combine the specificity of antibodies with the potency of cytotoxic “payload” drugs. Despite considerable progress in the field, critical questions remain about ADC uptake, trafficking, and catabolism; these factors may in turn influence the safety and efficacy of an ADC. To help address these questions, we are developing linker-payloads (LPs) and ADCs containing “clickable” moieties that can participate in bioorthogonal reactions with derivatized fluorescent probes and affinity tags. Specifically, we are preparing LPs derived from spliceostatin, a spliceosome inhibitor that represents a novel mechanistic class of ADC payloads. Because the intracellular fate of spliceostatin ADCs is poorly understood, methods that enable tracking of spliceostatin ADCs in cells should aid in the design of more effective next-generation ADCs.<br/><br/>First, we designed and synthesized a clickable spliceostatin LP: an azide handle was incorporated into the LP to enable selective reaction of the LP with alkyne-bearing probes. The clickable LP was successfully conjugated to trastuzumab, and the resultant ADC was found to be potent and selective, suggesting that the azide group does not interfere with activity. In addition, a lysosomal degradation assay showed that the azide group remains with the payload species during ADC catabolism, such that a probe attached to the azide should serve as a marker for payload localization. Subsequently, we demonstrated by LC-MS that the clickable ADC reacts quantitatively with acetylene- or cyclooctyne-bearing fluorophores via the azide-alkyne “click” reaction. We have translated these fluorophore-labeling results to imaging platforms in order to investigate the time-course of ADC uptake, trafficking, and payload release, with the overall objective of gaining a deeper understanding of ADC behavior.

Development of a clickable spliceostatin antibody-drug conjugate (ADC) to probe ADC uptake and trafficking in cancer cells

249th National Meeting (2015)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.