Funded Projects

Opioid use disorders (OUD) are a national public health emergency with more than 115 fatal overdoses occurring each day in the U.S. and an economic burden of more than $78 billion a year. Several medications are available for treating OUD, but their access is limited and efficacy is often sub-optimal. It is thus urgent to develop new, affordable strategies for the effective treatment of OUD. Immunopharmacotherapy has emerged as a promising treatment approach against OUD that relies on the induction of drug-specific antibodies to neutralize circulating drug molecules and reduce or cancel their effects. Several groups have attempted to apply this strategy with mixed results, suggesting that novel immunization platforms must be tested to further improve vaccine efficacy against OUD. This project will fabricate novel nanoparticle-based vaccines against OUD that are likely to boost their immunogenicity and lead to a more robust and effective immune response against the target opioid. The broad impact of this project resides in the rational design of nanoparticle-based vaccines that are safe and effective against opioids. This novel nanoparticle-based immunization strategy can be applied to the development of next-generation vaccines against a range of OUD and other substance use disorders.

Naltrexone (NTX) has proven to be an important, safe, and effective therapy for helping patients overcome opioid use disorders (OUD) and for preventing overdose. Unfortunately, the therapeutic potential of NTX has been blunted by poor adherence. To combat this issue, a system must be developed to deliver NTX for longer durations than currently available and with a more patient-friendly format. To address this problem, we will develop a long-acting and bioabsorbable NTX subcutaneous implant for the treatment of OUD. The proposed research will (a) determine the optimal chemical preparation of NTX inside the implant, (b) optimize the composition and porosity of the drug delivery substrate, and (c) refine the surgical procedure and instrumentation to be used during implantation. Once the safety and efficacy of this novel NTX implant is established, we will conduct the necessary clinical trials. The proposed study is highly relevant to and complementary of other efforts, either in consideration or already deployed to stem the tide of the lingering opioid crisis. If successful, this solution has the potential to enhance health, lengthen life, and reduce illness and disability for those suffering from OUD.

Opioids have been significantly over-prescribed and are associated with numerous deaths, resulting in the nation’s current opioid crisis. The FDA recently approved the ?2 adrenergic agonist lofexidine as a non-addictive, non-opioid treatment for opioid use disorder (OUD), but there is a continued, urgent need to develop additional pharmacological alternatives to address both pain and OUD. The psychoactive, natural product, Mitragyna speciosa (kratom), has triggered significant interest in this space because Mitragynine, its main alkaloid, can interact with both mu opioid and ?2 receptors, offering a totally new approach for treating OUD. This project involves the synthesis and research of a series of Mitragynine analogs to better understand the pharmacological mechanisms that underlie Mitragynine’s opioid and adrenergic activities. If successful, this project will result in templates for the design of novel opioid receptor ligands. This advance would greatly improve the knowledge of interactions of these structurally novel compounds with opioid receptors and facilitate the development of these ligands as treatments for OUD.

There are no FDA-approved medications for stimulant use disorders, and therapies for opioid use disorders remain suboptimal in ways that are now a focus of national attention. Thus, there is a clear need to identify new targets and explore new approaches for addiction medication development. Several lines of evidence suggest that PTPRD (receptor type protein tyrosine phosphatase D) may be a promising target for development of pharmacotherapeutics to treat not only stimulant use disorders but opioid use disorders as well. This research will focus on improving existing PTPRD ligands, identifying their effects on the dopamine and opioid systems, and moving the best novel, patentable PTPRD ligands toward human studies. If successful, this project will generate novel, well-tolerated, and bioavailable PTPRD ligands that display in vitro potency, selectivity and stability, and in vivo modulation of both cocaine and opioid-mediated reward at doses that present no significant toxicity.

To address the need for novel therapeutics for opioid use disorder (OUD), this research group identified ghrelin as an endogenous regulator of the mesocorticostriatal circuit, which contributes to the enhanced motivational attributes of addictive drugs and drug-associated cues. Ghrelin binds to the growth hormone secretagogue receptor 1? (GHS1?R) to transduce several physiological and behavioral processes, including the reward-related effects of opioid agonists. Systemic administration of a GHS1?R antagonist/inverse agonist dose-dependently attenuated self-administration of the addictive opioid analgesic oxycodone as well as oxycodone-seeking. This project proposes to employ a suite of validated rodent OUD models to define the preclinical profile for PF5190457, a selective GHS1?R antagonist/inverse agonist. PF5190457’s abuse liability, ability to suppress withdrawal and relapse-like behaviors, drug metabolism and pharmacokinetics, and brain penetrability in rats will be assessed. Phase 1 clinical studies in non–treatment seeking OUD participants will follow to assess the safety and tolerability of PF5190457.

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.

The expansion of opioid prescribing in recent years to better treat pain has markedly increased their usage and availability and fueled an epidemic of abuse. Up to 80 percent of addicts reported initiating their habit through prescriptions drugs. Decreasing opioid prescriptions would lower opioid exposure, with fewer people receiving the drugs and less drug available for diversion. Study investigators have identified a novel target in the brain, distinct from any of the traditional opioid receptors capable of mediating potent analgesia without the reward behavior and side effects seen with traditional opioids. They targeted this site with a series of arylepoxamides and have identified a clinical candidate (MP1000) and backup compound. MP1000 is a potent analgesic in a range of thermal, inflammatory, and neuropathic analgesic assays. It fails to show reward behavior and does not produce respiratory depression at doses 5-fold greater than its analgesic ED50. Chronic administration does not produce physical dependence or withdrawal when challenged with an antagonist. It shows no cross tolerance to morphine and can be co-administered to subjects already on opioids for pain to lower their opioid usage (i.e., opioid sparing), facilitating the eventual discontinuation of the opioid. If successful, this project could lead to the development of a viable alternative to current opioid-based analgesics with reduced side effects (such as reward and respiratory depression) compared to opioids.

Levo-alpha-acetylmethadol (LAAM) offers numerous behavioral and clinical advantages for select opioid use disorder (OUD) patients who do not respond to standard treatment. While LAAM was withdrawn from the market despite being approved for OUD treatment, this project seeks to develop novel, patentable, convenient dosage forms of LAAM, including novel LAAM oral dosage formulations and novel buccal film formulations of LAAM. Morphology, mechanical property, drug release kinetics, and stability of the oral dosage and buccal film formulations will be characterized to determine the instant release or steady release of LAAM, respectively. The two lead LAAM formulations with adequate release and stability profiles will be chosen through optimization studies both in vitro and in vivo. A human pharmacokinetic/pharmacodynamic study will then be carried out on the two selected formulations.