Helping to End Addiction Long-term (HEAL): Probe/Drug Lead Production

National Center For Advancing Translational Sciences

Investigators

Linked publications & trials

Abstract

HEAL Compound Library (created by ETB) With nearly 3,000 small molecules, the HEAL Target and Compound Library is the first to assemble known and potentially novel targets related to addiction, pain, and overdose in one collection. The library can be made available for meritorious HEAL-related assays through NCATS DPI in pre-spotted plates. Adenylyl Cyclase 1 (AC1) Inhibitors as Opioid Alternatives for Chronic and Inflammatory Pain Neuronal adenylyl cyclase type I (AC1) is a highly expressed enzyme in neuronal tissues associated with pain processing and neuronal plasticity. Preclinical studies showed that AC1 could be a promising target to treat chronic and inflammatory pain. This project is focused on the development and mechanistic characterization of AC1selective, CNS penetrant small molecule inhibitors as a nonopioid treatment for chronic pain. The team successfully miniaturized the cAMP HTRF assay for 1536-well plates. Over 56,000 compounds have been screened thus far; 65 select hits were sent to the collaborator for confirmation. Data analysis is ongoing. The AC1 team is set to collaborate with NCI to screen the Natural Products Library (a copy is housed at NCATS) as well. Identification of Brain-Permeant Small Molecule Modulators of GAL1R Receptor Mu-opioid receptors (MOR) mediate the analgesic and addictive effects of opioids. Galanin (a neuropeptide) exerts analgesic effects by acting on galanin 1 receptor (Gal1R) localized in the spinal cord. Galanin counteracts the addictive effects of opioids by acting on Gal1R that forms complexes with MOR localized in the mesencephalon; furthermore, Gal1R mediates the dopaminergic effects of opioids. This project is looking for potent and selective Gal1R ligands with the ability to cross the blood-brain barrier (BBB) and provide strong analgesia with low abuse liability when combined with opioids. With the publication of the Gal1R crystal structure, the team conducted structural modeling of lead compounds. Structure-activity-relationship (SAR) studies are underway after the completion of multiple screens and hit validation: the team made 50 analogs to date, and analog purification is in progress. Additionally, the team screened over 150,000 natural products fractions from the NCI Natural Products Library; follow-up testing on the hits is ongoing. High Throughput Screen to Identify Glutamate Carboxypeptidase II (GCPII) Brain-Penetrable-Inhibitors for the Treatment of Pain GCPII is a membrane-bound, zinc metalloenzyme that catalyzes the hydrolysis of neuropeptide N-acetyl-aspartate-glutamate (NAAG) to N-acetyl-aspartate (NAA) and glutamate. Inhibition of GCPII in the brain results in increased extracellular NAAG and decreased extracellular glutamate. These effects diminish glutamate transmission, which is associated with pain sensation and transmission, and no inhibitors have moved into the clinic yet. This project is focused on the identification of brain penetrable, small molecule inhibitors of GCPII. The team completed the proposed screening (over 30,000 compounds plus virtual screening). Batches of compounds were shipped to the collaborator for validation. Newly synthesized hits and SAR analogs are being tested. Some of the recent hits failed to confirm with fresh powders, but expanded screening is underway. The collaborator is in the process of obtaining a CNS-focused library, and a copy of it will be sent to NCATS for a future screen. Development of Gpr151 Modulators for the Treatment of Opioid Dependence This collaboration is developing novel Gpr151 modulators to facilitate long-term abstinence in opioid-dependent individuals. Gpr151 is an orphan G-protein coupled receptor expressed in the central nervous system (CNS), medial habenula, and immune system. With two stages of HTS complete (over 52,150 compounds screened), the team cherry-picked promising, efficacious hits for follow-up and cross-validation. The collaborator is in the process of validating these hits, and new analogs from the collaborator are being tested. NCATS is optimizing another assay as well. The team also screened over 150,000 natural products from the NCI Natural Products Library, and follow-up testing is in progress. Optimization of Allosteric Regulators of the NaV1.7 Sodium Channel for Chemotherapy-induced Peripheral Neuropathy (CIPN) Long-term use of opioids to treat chronic pain caused by CIPN can result in tolerance and addiction. There is a need for safe, non-addictive drugs for those that suffer from neuropathic pain. The project team is optimizing a novel lead series of NaV1.7 sodium channel allosteric regulators, such that one lead reaches the stage of a clinical candidate. After the completion of HTS, SAR studies and assessment of hERG activity are ongoing; the team synthesized hundreds of analogs based on top hits from HTS and virtual screening. The team is optimizing select analogs to find the best balance of potency, cytotoxicity, microsomal stability, PK, and hERG activity. Two hundred compounds will be assessed in a HT patch clamp assay as well. Npr1 Antagonists for Pain and Itch Pain and itch are considered nociceptive stimuli and produce aversive unpleasant sensations. Opioids, which are often used to control pain, can elicit strong pruriceptive responses. Alternatives to opioids for treatment of pain would reduce the pruritic burden caused by their use. The overall goal of this project is to develop hNpr1 antagonists with higher potencies and greater selectivity as candidates to treat itch at the level of neural transmission. The project team is analyzing a short list of previously identified chemotype representatives for initial testing. They will screen the NCI Natural Products Library and other libraries at NCATS (including HEAL). Chemical Modulators of the PIEZO2 Mechanoreceptor for the Study and Treatment of Pain PIEZO2 (a stretch-gated ion channel) was identified as a novel pain target. Human subjects with inherited loss-of-function mutations in this gene fail to develop mechanical allodynia. Its suggested that topical PlEZO2 antagonists may be effective for treating this type of pain. PIEZO2 loss-of-function has been linked to chronic itch as well, implying that a topical PIEZO2 agonist may be an effective itch treatment. The goal of this collaboration is to characterize small molecule probes for PIEZO2. The team engineered and characterized a stable, mechanically excitable HEK cell line that expresses different genes for HTS. Once HTS is complete, hits will be validated and optimized. Leads will be tested in animal models to demonstrate target engagement and efficacy. A proof-of-concept study is also underway to see if antibodies can restrict function when targeting separate regions of the channel. Substance P Antibody Development Blocking the interaction between inflammatory neuropeptides and their receptors is an approach for treating chronic pain and migraine. Small molecule antagonists have failed due to multiple receptors per peptide; however, theres been success using antibodies to block the function of CGRP, an inflammatory neuropeptide. Unfortunately, these antibodies do not cross the BBB. This project aims to develop cell-based assays and identify BBB-penetrant, functional antibodies to neuropeptides with roles in chronic pain and migraine. The team tested custom anti-Substance P antibody but found low affinity. Additional panning and multimerization is being explored to increase activity for Substance P nanobodies. 5-HT7 Receptor Agonists as Novel Treatments for Pain, Opioid-Induced Hyperalgesia, and Opioid Use Disorder G-coupled 5-HT7 serotonin receptor (5-HT7R) is a novel molecular target for pain. This project evaluated known agonists and furthered their preclinical development through pharmacokinetic (PK) studies. It was completed in FY21