(1056-A) Re-imagining Drug Discovery using Automated Ambient Mass Spectrometry

Abstract: The early drug discovery workflow relies heavily on high-throughput experimentation, both in terms of organic synthesis as well as analysis of complex biosamples. The identification of new biological targets through large-scale biospecimen studies, the generation of large sets of drug candidates and their rapid bioactivity screening, as well as the in vitro and cell-based confirmation of hits followed by lead optimization, all rely on high-throughput strategies which are typically spread out across diverse technologies in specialized facilities. The efficiency of this workflow could benefit from the consolidation of these activities in a single closed-loop platform. Mass spectrometry (MS) is an attractive technique to achieve such consolidation due to the inherent speed of mass analysis, however this advantage is rarely fully utilized due to the widespread use of sample purification approaches (e.g. chromatography) prior to MS.

Here we describe an automated system that achieves the consolidation of the early drug discovery pipeline by leveraging the advantages of desorption electrospray ionization (DESI), an ambient ionization technique that allows for the rapid and direct analysis of complex samples, both in qualitative and quantitative manner, without any need for workup. This system results from the combination of custom and commercial software, robotics, and analytical instrumentation, and it is capable of achieving throughputs better than 1 Hz using high-density arrays (up to 6,144 samples per array) and 50-nL samples ( < 5 ng analyte). More significantly, inherent reaction acceleration in the DESI microdroplets allows reaction time to be reduced to milliseconds.

The workflow of this platform involves automated sample preparation or manipulation using a fluid handling workstation, generation of microarrays on PTFE-coated slides using a pin-tool, automated transfer and analysis of spotted slides using high-throughput DESI-MS, and real-time processing of the spectral data. This methodology has been extensively demonstrated for the screening of organic reactions for identification of optimal synthesis conditions and the selective late-stage functionalization of complex molecules, as well as label-free quantitative biological assays using purified targets (e.g. enzymes, receptors), cell cultures, microorganisms, or tissue biopsies, all without sample cleanup. Examples of all these capabilities will be provided and framed within the overall context of drug discovery, where the untargeted analysis of biospecimens using DESI-MS led to the identification of the sulfotransferase 2B1b as a potential enzymatic target for prostate cancer, and the same ambient MS technology was utilized for the kinetic characterization of this enzyme, a large-scale inhibitor screening campaign and the subsequent cell-based hit confirmation, as well as synthetic strategies towards lead optimization.

This presentation will showcase both the original iteration of this automated platform, developed throughout the DARPA Make It program, as well as a new-generation system built within the ASPIRE initiative of the US National Center for Advancing Translational Sciences.