Funded Projects

We propose to develop a safe and effective nonopioid analgesic to treat neuropathic pain that targets an isoform of the voltage-gated sodium ion channel, NaV1.7. Voltage-gated sodium channels are involved in the transmission of nociceptive signals from their site of origin in the peripheral terminals of DRG neurons to the synaptic terminals in the dorsal horn. NaV1.7 is the most abundant tetrodotoxin-sensitive sodium channel in small diameter myelinated and unmyelinated afferents, where it has been shown to modulate excitability and set the threshold for action potentials. Development of systemic NaV1.7 inhibitors has been complicated by the challenge of achieving selectivity over other NaV isoforms expressed throughout the body. We have discovered a series of potent, state-independent NaV1.7 inhibitors that exhibit >1000-fold selectivity over other human isoforms. Work conducted under this program will support advancement of a lead candidate into clinical development as a therapeutic for neuropathic pain.

Most of the 200k Americans who undergo thoracotomy each year receive opiates to reduce postoperative pain because clinicians have few non-addictive, cost-effective choices to control the severe pain patients often experience in the first two weeks after surgery. Managing pain post-thoracotomy is critical to enable patients to take deep breaths and remove (via coughing) lung secretions that otherwise significantly increase risk of pneumonia and collapsed lung, hospital re-admission and morbidity. The most severe pain associated with thoracotomy is transmitted along the intercostal nerves, but no long-term analgesic or nerve block device exists that can provide safe and effective long-term reduction of pain. A reversible, patient-controlled, non- addictive, intercostal nerve block device would reduce suffering due to thoracotomy, broken ribs and herpes zoster. In this Phase I project, the team will develop a minimally invasive thermal nerve block device that can control nerve conduction by gently warming and cooling a short nerve segment between room temperature and warm water temperature. This novel approach is based on the discovery that warm and cool temperature mechanisms of nerve block are different and additive, enabling moderate-temperature nerve block by cycling neural tissues slightly above and below body temperature. Reversible thermal nerve blocks represent a completely new approach to managing pain.  

In this study, 600 to 700 hemodialysis patients receiving chronic opioids will be randomized across the Hemodialysis Opioid Prescription Effort (HOPE) Consortium to enhanced treatment as usual, buprenorphine therapy, or buprenorphine plus mindfulness-based cognitive therapy intervention delivered by telephone and adapted for pain (MBCT-TP). The following specific aims will be assessed: Aim 1—to assess the effectiveness of buprenorphine in reducing chronic opioid use and prescriptions in hemodialysis patients on opioids at baseline, compared with an enhanced treatment as usual intervention and to assess the effectiveness of buprenorphine in improving pain intensity, quality of life measures, and hospitalizations; Aim 2—to assess the incremental effectiveness of MBCT-TP added to buprenorphine compared with buprenorphine alone on pain interference with physical, social, and mental functioning, opioid use, pain intensity, other quality of life measures, hospitalizations, and mortality.

This project will design and test optimized temporal patterns of stimulation to improve the efficacy of commercially available spinal cord stimulation (SCS) systems to treat chronic neuropathic pain. Researchers will build upon a validated biophysical model of the effects of SCS on sensory signal processing in neurons within the dorsal horn of the spinal cord to better understand how to improve the electrical stimulus patterns applied to the spinal cord. They will use sensitivity analyses to determine the robustness of stimulation patterns to variations in electrode positioning, selectivity of stimulation, and biophysical properties of the dorsal horn neural network. Researchers will demonstrate improvements from these new stimulus patterns by 1) measuring their effects on pain-related behavioral outcomes in a rat model of chronic neuropathic pain and by 2) quantifying the effects of optimized temporal patterns on spinal cord neuron activity. The outcome will be mechanistically derived and validated stimulus patterns that are significantly more efficacious than the phenomenologically derived standard of care patterns; these patterns could be implemented with either a software update or minor hardware modifications to existing SCS products.

Chronic focal neuropathic pain, which includes pain etiologies such as radiculopathy and radiculitis, focal peripheral neuropathies, and low back pain, affects as many as 25 million patients annually in the United States. Chronic focal neuropathic pain is maintained by genome-wide transcription regulation in the dorsal root ganglia (DRG) / spinal cord network. The transcription factors driving this regulation constitute a promising class of targets with the potential to alter the course of pain with a single treatment. DNA decoys are oligonucleotides that specifically inhibit the activity of certain transcription factors. AYX2 binds and inhibits Krüppel-like transcription factors (KLF) in the DRG-spinal cord. The goal of this Phase 1 proposal is to advance AYX2 toward an IND submission, allowing for human clinical trials. We propose in Aim 1 to characterize AYX2 pharmacokinetics in the cerebrospinal fluid and plasma and its distribution in the DRG, spinal cord and brain following an IT injection. With this information, AYX2 will be tested in a panel of complementary toxicology studies in Aim 2 to allow for final IND-enabling studies, supported by Phase 2 of the grant. This research will accelerate development of AYX2 as a novel drug candidate for the non-opioid treatment of pain.

Neuropathic pain conditions are exceedingly difficult to treat, and novel non-opioid analgesics are desperately needed. Receptomic and unbiased transcriptomic approaches recently identified the orphan G-protein coupled receptor (oGPCR), GPR160, as a major oGPCR whose transcript is significantly increased in the dorsal horn of the spinal cord (DH-SC) ipsilateral to nerve injury, in a model of traumatic nerve-injury induced neuropathic pain caused by constriction of the sciatic nerve in rats (CCI). De-orphanization of GPR160 led to the identification of cocaine- and amphetamine-regulated transcript peptide (CARTp) as a ligand which activates pathways crucial to persistent pain sensitization. This project will test the hypothesis that CARTp/GPR160 signaling in the spinal cord is essential for the development and maintenance of neuropathic pain states. It will also validate GPR160 as a non-opioid receptor target for therapeutic intervention in neuropathic pain, and characterize GPR160 coupling and downstream molecular signaling pathways underlying chronic neuropathic pain.

Research on optimal long-term opioid therapy (LTOT) tapering strategies has lagged behind clinical needs. Patients with end-stage renal disease (ESRD) receiving hemodialysis (HD) may be especially vulnerable. This study will adapt the Collaborative Opioid Reassessment Program (CORP) and Cooperative Pain Education and Self-Management (COPES) interventions for patients receiving HD and LTOT and test their effectiveness in a pragmatic sequential multiple assignment randomized trial (SMART) design. Initial randomization will be to compare CORP-supported taper with (CORP-B) and without (CORP) buprenorphine rotation on the six-month composite outcome of LTOT dose reduction and pain response. This design will allow determination of which of the eight adaptive treatment strategies leads to the greatest reduction in six-month opioid dose and pain interference.

Despite the pervasive use of opioid analgesics in the dialysis population and the substantial risks they engender, their efficacy is limited in treating common chronic pain conditions. Most patients receiving long-term opioid therapy continue to experience severe pain and functional limitations. To simultaneously address problems related to chronic pain and opioid use in the U.S. hemodialysis population, this study will evaluate tailored patient-centered interventions to manage pain and reduce opioid use. Patients will be assigned randomly to one of three groups over a 12-month study period: 1) pain care management (PCM) versus 2) PCM plus an online pain self-management program (PSM) that incorporates cognitive behavioral training and is delivered during dialysis sessions, versus 3) control with medication review and education. The study will also evaluate the effectiveness of offering buprenorphine by randomly assigning participants in both active treatment arms to being offered buprenorphine rotation versus continued standard opioid taper support without the option of buprenorphine.

It is unclear what changes in the brain mediate the development of chronic pain from acute pain and how chronic pain may change responses to opioid reward for the altered liability of opioid abuse under chronic pain. Preliminary studies have found that Dnmt3a, a DNA methyltransferase that catalyzes DNA methylation for gene repression, is significantly downregulated in the brain in a time-dependent manner during the development of chronic pain and after repeated opioid treatment. This project will investigate whether Dnmt3a acts as a key protein in the brain for the development of chronic pain, and whether Dnmt3a could be a novel epigenetic target for the development of new drugs and therapeutic options for the treatment of chronic pain while decreasing abuse liability of opioids.

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.

Prescriptions for narcotic pain relief after surgery result in unintended prolonged opioid use for hundreds of thousands of Americans. Nonpharmacological pain care is effective and recommended by guidelines for perioperative pain while offering a more favorable risk-benefit ratio. However, nonpharmacological pain care is rarely used as first or second-line therapy after surgery. Patient and clinician decision support interventions are effective in encouraging patient-centered and guideline-concordant care, but these strategies have not been tested pragmatically as a bundle in everyday postoperative pain care. The NOHARM trial will first confirm the feasibility of patient-facing and clinician-facing decision support components of an EHR-embedded evidence-based bundle. The investigators will test the bundle in a stepped-wedge cluster randomized trial. They will test a sustainable system strategy that could change the paradigm of perioperative pain management toward nonpharmacological options in a manner that preserves patient function, honors patient values, and maintains availability of opioids as a last resort.

Many chronic pain conditions are dependent upon activity of the sympathetic nervous system. Sympathetic blockade is used clinically in chronic pain conditions, but the clinical and preclinical evidence for this practice is incomplete. We propose that certain pathological pain conditions require intact sympathetic innervation of the sensory nervous system at the level of the dorsal root ganglion (DRG) and that release of sympathetic transmitters enhances local inflammation and leads to pain. Our preliminary data show large, rapid, and long-lasting reduction of pain behaviors and inflammatory responses following a"microsympathectomy" (mSYMPX) in both neuropathic and inflammatory pain models. Our aims are to: 1) characterize the effects of mSYMPX on pain and on local inflammation in the DRG; 2) explore the molecular mechanisms for sympathetic regulation of inflammatory responses in the DRG; and 3) assess the functional role of sympathetic transmitters in the sympathetically mediated inflammatory responses in the DRG.