Orthogonal Temperature-Related Intensity Change (TRIC) and TR-FRET as a High-Throughput Screening Platform for the Discovery of SLIT2 Binders: A Proof-of-Concept Approach

SLIT2, a secreted glycoprotein involved in axon guidance, immune modulation, and tumor progression, remains largely unexplored as a pharmacological target due to the absence of small-molecule modulators. Here, we present a proof-of-concept high-throughput screening platform that integrates Temperature-Related Intensity Change (TRIC) technology with time-resolved Förster resonance energy transfer (TR-FRET) to identify small molecules capable of disrupting the SLIT2/ROBO1 interaction. Screening a lipid metabolism-focused compound library (653 molecules) yielded bexarotene, as the most potent small molecule SLIT2 binder reported to date, with a dissociation constant (KD) of 2.62 µM. Follow-up TR-FRET assays demonstrated dose-dependent inhibition of SLIT2/ROBO1 interaction, with relative half-maximal inhibitory concentration (relative IC50) = 77.27 ± 17.32 µM, with a maximal inhibition (Imax) of ∼40 % at 400 µM. These findings suggest a novel extracellular activity of bexarotene and validate the combined use of TRIC and TR-FRET as a scalable screening strategy for SLIT2-targeted small molecules. This platform lays the groundwork for future high-throughput discovery efforts against SLIT2 and its signaling axis.