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

National Center For Advancing Translational Sciences

Investigators

Linked publications, trials & patents

Abstract

HEAL Compound Library 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; select hits from 30 different chemotypes were confirmed active by our collaborator. BBB permeability and PK assays on these chemotypes are complete; the team is following-up on the top chemotypes. The team also screened the first release of the NCI Natural Products Library (a copy is housed at NCATS) and will work on follow-up testing next. Identification of Brain-Permeant Small Molecule Modulators of GAL1R Receptor 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. The team identified two selective agonist chemotypes and one positive allosteric modulator. Structure-activity-relationship (SAR) studies are underway: the team made over 50 analogs to date, and analog purification is in progress. Additionally, we screened over 150,000 natural products fractions from the NCI Natural Products Library; confirmation testing is complete, and there are plans to screen the next release of this library. High Throughput Screen to Identify Glutamate Carboxypeptidase II (GCPII) Brain-Penetrable-Inhibitors for the Treatment of Pain 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 developed a 384-well GCPII Dual Stream Liquid Chromatography with Tandem Mass Spectrometry (LC/MS/MS) assay for this project. It led to the establishment of a MS-based HTS group at NCATS. The team screened over 149,000 compounds to date, and compounds were shipped to the collaborator for validation in their radioactivity-based assay. Some of the recent hits failed to confirm with fresh powders, but expanded and follow-up screening are underway. Development of Gpr151 Modulators for the Treatment of Opioid Dependence Gpr151 is an orphan G-protein coupled receptor expressed in the central nervous system (CNS), medial habenula, and immune system. The team developed primary, counter, orthogonal, and electrophysiology assays for this project. With multiple stages of HTS complete (over 76,000 compounds screened), the team cherry-picked promising, efficacious hits for follow-up and cross-validation. Five lead chemotypes were generated, and early SAR studies are underway. Leads will be validated in the collaborators animal addiction model. The team also screened over 150,000 natural products from the NCI Natural Products Library, and confirmation testing is complete; the next release of this library will be screened. To date, this project has identified first-in-class GPR151 modulators and accelerated further understanding of GPR151. Optimization of Allosteric Regulators of the NaV1.7 Sodium Channel for Chemotherapy-induced Peripheral Neuropathy (CIPN) 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. The team synthesized hundreds of analogs based on top hits from HTS and structurally distinct hits from virtual screening. We developed rDRG, human iPSC-derived nociceptors, and hERG assays to support medicinal chemistry efforts. The team designed and synthesized novel and orally bioavailable bicyclic heteroaryl regulators that blocked SUMOylation of CRMP2. We are optimizing select analogs to find the best balance of potency, cytotoxicity, microsomal stability, pharmacokinetics (PK), and hERG activity. Two hundred compounds are being 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 screened five of NCATS libraries in addition to the NCI Natural Products Library. We are evaluating over 80 million data points and establishing cherry pick criteria to select the best hits from the primary screens. Chemical Modulators of the PIEZO2 Mechanoreceptor for the Study and Treatment of Pain PIEZO2 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 team engineered and characterized a stable, mechanically excitable HEK cell line that expresses different genes for HTS. An eHEK cell line expressing PIEZO1 for selective counterscreening was also developed. Screening of an optimized and miniaturized 1536-well agonist assay is complete, and HTS is underway. (An antagonist assay is currently being optimized.) Hits will be validated and optimized once HTS is complete. 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. The project was halted because it was difficult to obtain high-affinity neutralizing antibodies or nanobodies.