Signaling pathways and their protein target constituents (e.g. kinases) have become important therapeutic targets in many disease areas. Traditional selectivity profiling for kinase inhibitors has relied upon screening panels of recombinant enzymes in biochemical assay formats. Recent studies have highlighted the importance of using cellular assays to better approximate true biological selectivity. We have developed a portfolio of CellSensor beta-lactamase transcriptional reporter gene assays that can be used to screen for perturbagens of various endogenous signaling pathways. Here we describe a multi-pathway profiling approach for generating compound-pathway selectivity maps. To demonstrate the utility of this approach, we have screened 32 known compounds across a diverse panel of 12 key signaling pathways and generated the first comprehensive cellular pathway selectivity profiles of several clinically approved kinase and other well-known bioactive inhibitors. Selectivity score comparisons identified several kinase inhibitors that were more promiscuous than predicted by traditional biochemical profiling methods. For example, we identified effects of sorafenib on the JAK/STAT pathway and demonstrated the potential therapeutic indication of sorafenib in treating leukemia/myeloproliferative disorder patients harboring TEL-JAK2 or JAK2V617F mutations. Our results indicate that multi-pathway profiling can efficiently characterize both on and off-pathway compound activities, revealing potential novel pathways and opportunities for drug repositioning purposes and/or safety liabilities in one profiling campaign.

Trk receptor tyrosine kinases are required for signal transduction initiated by neurotrophins leading to cell proliferation, differentiation, survival and death. Alterations in Trk kinase activity have been linked to various diseases. To address the need for cell-based assays for screening and studying the selectivity of Trk kinase modulators, we developed high-throughput cell-based assays for Trk receptor kinases using nuclear factor of activated T-cells (NFAT) beta-lactamase reporter lines stably expressing full length human Trk kinases. These assays were functionally validated with cognate neurotrophin(s), inhibitors and TRK RNAi oligos and demonstrated for their utility in identifying potent and selective modulators of Trk receptor kinases.