High-throughput discovery platform for modulators of cardiac muscle proteins to treat heart failure

Project Summary This Phase I SBIR collaboration between Photonic Pharma LLC (PP) and the University of Arizona (UA) will establish proof-of-concept for an innovative drug-discovery campaign for treatment of heart failure (HF), targeting cardiac myosin-binding protein C (MyBP-C). There is an urgent need for novel therapies for HF, a major health problem affecting 1 in 30 adults in the US. MyBP-C has been identified as a therapeutic target for correcting HF. Phosphorylation affects N-terminal MyBP-C structure, affecting its binding to actin and myosin, modulating contraction and relaxation. Therefore, targeting MyBP-C with drugs that mimic phosphorylation and/or modulate its binding to actin or myosin is a promising approach to treatment of heart failure. PP has developed patented technology for fluorescent protein biosensors and high-throughput screening (HTS) based on time-resolved fluorescence lifetime (FLT) detection, seeking breakthroughs in the early phase of drug discovery with unprecedented quality, speed, and precision. UA brings expertise in MyBP-C and cardiac muscle biophysics, biochemistry, and physiology. In a new publication, this collaborative team has identified the first compounds that bind to MyBP-C and modulate its interaction with actin. The goal of this project is to demonstrate proof-of-concept that drug targeting of MyBP-C is a powerful platform for discovery of novel therapies to affect cardiac muscle protein function and ultimately patient outcomes in heart failure. Aim 1 studies will use a primary HTS assay of a 50,000-compound library of diverse and drug-like small molecules (now justified by recently completed screens on a small validation library), using a novel FRET assay, to find compounds that affect the interaction of MyBP-C-with actin. The fluorescence lifetime FRET (FLT-FRET) assay uses site-specific fluorescent probes attached to actin and MyBP-C domains C0-C2. FLT measurements provide a precise readout of protein binding and conformation. Small-molecule Hits will be evaluated to select compounds with highest affinity interactions and/or sensitivity to phosphorylation. Aim 2 studies will use secondary assays (lower throughput) to determine efficacy of Hit compounds on function. Selected compounds will be evaluated by biochemical, biophysical, and physiological assays for effects on MyBP-C function, actin binding, and contractility in cardiac cells. These novel screening strategies address the key missing aspect, early-phase structure-based drug discovery, to enable MyBP-C therapeutic development, as needed to fine- tune contractility and improve patient quality of life and survival. In Phase I we will validate the HTS assay for application to commercial-scale drug screening. In Phase II we will enhance potency and specificity with medicinal chemistry, evaluating the most promising compounds in increasingly physiological/pathological conditions for the heart failure indication. Letters from major pharmaceutical companies indicate great commercial potential for this technology, applied to this specific target and others. Our long-term goal: address the unmet need for novel heart failure therapies that are commercially validated.