Funded Projects

Patients with severe, intractable chronic pain primarily receive treatment with opioids, and non-opioid treatment options are urgently needed. These patients may be candidates for treatment using other types of pain medications administered via intrathecal injection—that is, injection directly into the fluid-filled space between the membranes surrounding the brain and spinal cord. Intrathecal injection requires much lower medication doses than systemic administration. Centrexion Therapeutics Corporation seeks to develop CNTX-3100, a highly selective and highly potent novel small molecule that activates the nociception receptor (NOPr), for intrathecal administration using a pump approved by the U.S. Food and Drug Administration. In animal studies, such NOPr agonists had powerful analgesic effects when delivered directly to the spinal cord by intrathecal administration. CNTX-3100 has ideal properties for intrathecal delivery and in animal studies provided pain relief and a safety profile that was superior to intrathecally administered morphine. This project will scale up the drug, develop a formulation that ensures a stable product for intrathecal delivery, and conduct preclinical toxicity studies to prepare for a Phase 1 clinical trial.

Efforts to identify non-opioid analgesics for treatment of chronic pain have identified a protein, carbonic anhydrase-8 (CA8), in pain-sensing nerve cells in the spinal cord (dorsal root ganglion cells) whose expression regulates analgesic responses. Gene therapy delivering CA8 to dorsal root ganglion cells through clinically relevant routes of administration functions as a “local anesthetic” that induces long-lasting pain relief in animal models of chronic pain. This project will further develop CA8 gene therapy with the goal of treating chronic knee osteoarthritis pain. It will assess several gene therapy constructs to determine the doses needed, safety, efficacy, and specificity to nerve cells for each construct. It will then select the safest and most effective construct that can be administered via the least invasive route for further development. The project will include all steps necessary to identify one candidate gene therapy construct that will be suitable to begin clinical trials in patients with chronic knee osteoarthritis pain.

Although opioid-based analgesics have been proven effective in reducing the intensity of pain for many neuropathic pain conditions, their clinical utility is grossly limited due to the substantial risks involved in such therapy, including nausea, constipation, physical dependence, tolerance, and respiratory depression. Cumulative evidence suggests that human Mas-related G protein-coupled receptor X1 (MRGPRX1) is a promising target for pain with limited side effects due to its restricted expression in nociceptors within the peripheral nervous system; however, direct activation of MRGPRX1 at peripheral terminals is expected to induce itch side effects, limiting the therapeutic utility of orthosteric MRGPRX1 agonists. This finding led to the exploration of positive allosteric modulators (PAMs) of MRGPRX1 to potentiate the effects of the endogenous agonists at the central terminals of sensory neurons without activating peripheral MRGPRX1. An intrathecal injection of a prototype MRGPRX1 PAM, ML382, effectively attenuated evoked, persistent, and spontaneous pain without causing itch side effects. The goal of this study is to develop a CNS-penetrant small-molecule MRGPRX1 PAM that can be given orally to treat neuropathic pain conditions.

Pain signals originate predominantly in a subset of peripheral sensory neurons that harbor a distinct subset of voltage-gated sodium (NaV) channels; however, current NaV channel blockers, such as local anesthetics, are non-selective and also block NaV channels vital for function of the heart, muscle, and central nervous system. Genetic studies have identified human NaV1.7, NaV1.8, and NaV1.9 channel subtypes as key players in pain signaling and as major contributors to action potential generation in peripheral neurons. ProTx-II is a highly potent and moderately selective peptide toxin that inhibits human NaV1.7 activation. This study will optimize ProTx-II selectivity, potency, and stability by exploiting the new structures of ProTx-II—human NaV1.7 channel complexes, advances in rational peptide optimization, and rigorous potency and efficacy screens to generate high-affinity, selective inhibitors of human NaV1.7, NaV1.8, and NaV1.9 channels that can define a new class of biologics to treat pain.

The development of non-addictive pain therapeutics can help counter opioid addiction and benefit patients, including those who suffer from neuropathic pain, in particular diabetic neuropathic pain (DNP). This project’s goal is to develop a safe, efficacious, and non-addictive small-molecule drug that activates Kv7 voltage-gated potassium channels to address overactive neuronal activity in DNP. Researchers will discover Kv7 activators that favor Kv7 isoforms altered in DNP and found in dorsal root ganglia, decrease off-target side effects observed with the use of earlier non-biased Kv7 activators, and optimize the absorption, distribution, metabolism, excretion, and toxicity profiles of these activators. This screening paradigm is intended to establish a clinic-ready, well-tolerated, and widely effective product to treat neuropathic pain.