Funded Projects

Chronic pain affects an estimated 100 million Americans, or one third of the U.S. population, and it is the primary reason Americans are on disability. Although many treatments are available for pain, the most potent class of analgesics relies on opioid analogs, whose limitations and well-known adverse effects have contributed to the present opioid crisis. New pharmacotherapies for pain management are sorely needed. MTX1604, a synthetic endomorphin analog, has emerged as a highly effective analgesic that exhibits reduced reward potential and respiratory suppression, and a robust duration of efficacy in a variety of validated animal models of acute, neuropathic, inflammatory, post-operative, and visceral pain. This project will generate additional preclinical characterization data of MTX1604 and advance clinical development toward FDA approval. If successful, this medication development project could offer patients a novel non-addictive, potent, and safe analgesic and thus have a direct impact on the opioid crisis.

The adverse effects of morphine and other mu-opioid receptor (MOR) agonists are linked to the ?-arrestin pathway, while analgesia is tied to the G-protein pathway. Pathway specific or “biased” drug development can target G-protein specific agonists that avoid the negative consequences of ?-arrestin signaling activation and produce analgesia. Highly “biased” MOR agonists have promise as effective analgesics but devoid of opioid-induced adverse effects. Preclinical studies compared two compounds, MEB-1166 and MEB-1170, against Oliceridine and morphine. Both compounds displayed no respiratory depression, even at high doses, while morphine and Oliceridine significantly reduced respiratory function. In contrast to morphine, neither MEB-1166 nor MEB-1170 produced conditioned place preference, suggesting an absence of abuse liability. This study will characterize the pharmaceutical and pharmacological profiles and perform liability studies for these compounds.

Methadone is useful in the treatment of opioid dependence; however, methadone misuse and methadone-related fatalities have increased. Ensysce has created two complementary, novel technologies that can be applied to methadone. Their Trypsin Activated Abuse Protection (TAAP™) prodrugs are “enzyme-activated” to release clinically effective opioid drugs only when taken orally and exposed to the correct physiologic conditions, such as exposure to trypsin in the small bowel. Their multi-pill abuse resistance (MPAR™) feature involves in situ bioregulation of opioid delivery from the TAAP™ systems, enabling control over oral multi-dose pharmacokinetic profiles. It is envisaged that an R-methadone-TAAP™ prodrug would demonstrate similar reduced addiction liability as with other opioid-TAAP products. The objective of this proposal is to develop an R-methadone-TAAP™/MPAR™ drug through Phase 1 clinical studies and to translate R-methadone-TAAP™/MPAR™ results into humans, to ultimately reduce the misuse and oral overdose potential of methadone.

This project proposes to develop novel Gpr151 antagonists to facilitate long-term abstinence in opioid-dependent individuals. Gpr151 is an orphan G-protein coupled receptor that is expressed almost exclusively in the medial habenula and co-localizes with ?-opioid receptors to regulate the inhibitory effects of opioids on habenular neurons. Mice with a null mutation in Gpr151 (Gpr151-/- mice) are resistant to the stimulant and rewarding effects of opioids and self-administer lower quantities of oxycodone. Based on this preliminary work, the study will seek to identify Gpr151 antagonists through a variety of methods and optimize them for potency, selectivity, drug metabolism, pharmacokinetics, and brain penetration properties. The study will evaluate effects of those with the most favorable drug-like physiochemical properties on electrophysiological responses of medial habenula to opioid drugs and assess the in vivo efficacy of these novel antagonists in wild-type and Gpr151-/- mice.

Extended-release naltrexone (XR-NTX) reduces overdose risk; however, transitioning to XR-NTX requires detoxification, which is a major hurdle. Non-opioid detoxification with an alpha-2 adrenergic receptor agonist, such as lofexidine, may shorten detoxification time, but it does not reduce the subjective effects of withdrawal. Pregabalin potentiates the activity of glutamic acid decarboxylase, inhibits calcium influx and release of excitatory neurotransmitters, raises GABA levels, and is approved for neuropathic pain, for fibromyalgia, and as an adjunctive therapy for adults with partial onset seizures. The study will test whether pregabalin can be combined with lofexidine to better reduce the subjective effects of opioid withdrawal than lofexidine alone and increase the proportion of patients that transition to XR-NTX. Such a dosing combination could lower the detoxification hurdle for patients who are interested in antagonist treatment or who are in settings where it is unavailable or difficult to access.

In collaboration with Eolas Therapeutics and the NIH Blueprint Neurotherapeutics Network, AstraZeneca has developed a novel compound for treatment of opioid use disorder, AZD4041, which targets orexin 1 (OX1) receptors in the brain. In animal studies, AZD4041 reduced the motivation to consume opioids or nicotine, reduced relapse-like drug-seeking behaviors, and showed a favorable safety profile. The compound also has proven to be safe in an initial Phase 1 clinical trial in healthy human volunteers. This project will further evaluate the safety (e.g., respiratory depression profile) of AZD4041 in human volunteers, using multiple and increasing doses. Upon successful completion of these studies, the compound will be tested in a proof-of-concept efficacy study in patients with opioid use disorder. If this is successful, the compound will advance to larger Phase 2 and Phase 3 pivotal clinical trial to tests its effectiveness in the treatment of opioid use disorder.

A recent FDA public meeting identified sleep disturbance as a primary contributor to opioid use disorder (OUD) treatment failure. Suvorexant (SUVO; Belsomra®) is a dual orexin receptor antagonist that is FDA-approved for insomnia, with low addiction liability, that improves sleep continuity with a single dose, has an extremely safe and mild side-effect profile, has clear interactions with the opioid system, and has not yet been evaluated in OUD patients. The hypothesis is that SUVO will improve total sleep time during withdrawal, have no addiction liability, and be more efficacious than trazodone, a common OUD-associated insomnia medication. Primary outcomes will be objective sleep measures and addiction liability. Secondary measures will include objective, biological, and self-report measures of opioid withdrawal severity, treatment retention, craving, and stress. Results will advance the treatment of OUD, the understanding of sleep and opioids, and the use of SUVO in clinical populations.

There is a need for pharmacologic treatment options for opioid use disorder (OUD) that do not pose addiction liability and do not require complete withdrawal from opioids prior to treatment. Nonclinical studies support a role for the orexin system in drug seeking; compounds that selectively block signaling at the orexin-1 receptor (OX1R) reduce drug use. C4X3256, a non-opioid, highly selective OX1R antagonist, has a long residence time at the OX1R along with reduced intravenous self-administration and cue-induced reinstatement in animal models of nicotine addiction, suggesting it could be an addiction treatment. Proposed studies will move C4X3256 from preclinical development through Phase I testing in subjects with OUD. The clinical, preclinical, and supporting pharmaceutical development studies proposed will allow C4X3256 to move to Phase II studies.

Opioids can be effective analgesics but can also be fatal due to opioid-induced respiratory depression after overdose. This project will use cutting-edge molecular, physiological, behavioral, and imaging techniques to better understand and distinguish opioid-induced respiratory depression and opioid-mediated analgesia. Nerve cell-specific, single-cell transcriptomic analysis will be used to identify functional markers expressed in nerve cells that play a specific role in opioid-induced respiratory depression, but not opioid analgesia. This research study will help to identify novel therapeutic targets that could selectively rescue opioid-induced respiratory depression while maintaining the beneficial pain-relieving effects of opioids. 

Exposure to opioid analgesics during medical care is a key driver of the opioid epidemic. Such exposures are widespread. Yet opioids remain essential first-line agents in treating pain, and it remains vital that pain be appropriately managed. Non-opioid pain treatments help to resolve the opioid/pain conflict. This project will examine the opioid-sparing and pain-relieving potential of a novel, non-pharmacological treatment for pain, using the effects of green light exposure to reduce pain and thereby reduce the quantity of opioids needed for pain relief.