Identification of Cyclic Peptide Antagonists of an Anti-Opioid G Protein-Coupled Receptor

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Identification of Cyclic Peptide Antagonists of an Anti-Opioid G Protein-Coupled Receptor RFA-DA-19-019 R43 Phase I SBIR PI: Sid A. labed Project Summary The highly addictive properties of opioid drugs, coupled with routine over-prescription, have resulted in a national crisis. Accidental overdose by opioids has increased over 400% in the last 15 years, from ~8,000 opioid- related overdoses to more than 30,000 in 2015. The staggering cost of the opioid health crisis to the American public exceeds $50 billion annually, highlighting the need for safer therapeutics for pain management. Drs. Kirill Martemyanov and Brock Grill at the Scripps Institute, Florida, have engineered a model system expressing a functional mammalian opioid receptor (MOR) in the model nematode Caenorhabditis elegans for discovery of opioid modulators. Using this system, they identified an orphan G Protein Coupled Receptor, GPR139, as a negative regulator of MOR signaling. In mammals, GPR139 is co-expressed with MOR in opioid-sensitive brain regions and influences MOR trafficking and signaling. Deletion of GPR139 in mice enhanced opioid-induced inhibition of neuronal firing, increased the analgesic and rewarding effects of morphine, and reduced withdrawal. Previous efforts to target GPR139, which have largely focused on identification of small molecule agonists, has failed to produce a therapeutic candidate antagonist with favorable pharmacological properties. To address this unmet need, EvoDenovo will screen an innovative library of cyclic peptides (CPs) for new GPR139 antagonists by combining two state-of-the-art C. elegans technologies exclusive to EvoDenovo: 1) InVivo Display: a high-throughput screening technology invented by EvoDenovo that can be used for peptide-based drug discovery that bypasses the necessity of peptide purification by directly feeding live recombinant E. coli clones, each expressing a different cyclic peptide, directly to nematodes expressing mammalian MOR and human GP139. This drastically reduces the cost and time for screening. 2) The anti-opioid behavior platform developed at Scripps by Drs. Martemyanov and Gril that assesses the behavioral effects of opioids and identifies pharmacological outcomes of different drugs. The combination of both platforms, assisted by an automated C. elegans movement tracking system, will yield a powerful high throughput screening engine capable of interrogating thousands of recombinant peptides within a few days, all in a unique in vivo setup. GPR139 antagonists identified using this assay would likely be missed by conventional screening protocols. EvoDenovo uses CPs instead of linear peptides. The cyclization of peptides increases gut stability by eliminating vulnerable N- and C-termini, reduces susceptibility to proteolytic hydrolysis, and enhances membrane permeability. There are 2 specific aims: Aim 1: Perform a behavioral screen for cyclic peptide antagonists of GPR139 in C. elegans. Aim 2: Validate hits generated from the C. elegans platform in mammalian cell-based assays. This Phase I proposal will provide the foundation for a Phase II SBIR which will include a larger-scale screen and follow-up on prioritizing CP hits, mammalian testing, and IND enabling studies. EvoDenovo RFA-DA-19-019/ PI: Sid A. Labed Project Summary - Page 1 of 1