Mechanisms of cannabinoid tolerance

A cryptic pocket in CB1 drives peripheral and functional selectivity

The current opioid overdose epidemic highlights the urgent need to develop safer and more effective treatments for chronic pain1. Cannabinoid receptor type 1 (CB1) is a promising non-opioid target for pain relief, but its clinical use has been limited by centrally mediated psychoactivity and tolerance. We overcame both issues by designing peripherally restricted CB1 agonists that minimize arrestin recruitment. We achieved these goals by computationally designing positively charged derivatives of the potent CB1 agonist MDMB-Fubinaca2. We designed these ligands to occupy a cryptic pocket identified through molecular dynamics simulations-an extended binding pocket that opens rarely and leads to the conserved signalling residue D2.50 (ref. 3). We used structure determination, pharmacological assays and molecular dynamics simulations to verify the binding modes of these ligands and to determine the molecular mechanism by which they achieve this dampening of arrestin recruitment. Our lead ligand, VIP36, is highly peripherally restricted and demonstrates notable efficacy in three mouse pain models, with 100-fold dose separation between analgesic efficacy and centrally mediated side effects. VIP36 exerts analgesic efficacy through peripheral CB1 receptors and shows limited analgesic tolerance. These results show how targeting a cryptic pocket in a G-protein-coupled receptor can lead to enhanced peripheral selectivity, biased signalling, desired in vivo pharmacology and reduced adverse effects. This has substantial implications for chronic pain treatment but could also revolutionize the design of drugs targeting other G-protein-coupled receptors.

A novel injectable nanotherapeutic platform increasing the bioavailability and anti-tumor efficacy of Arachidonylcyclopropylamide on an ectopic non-small cell lung cancer xenograft model: A randomized controlled trial

Rapid progressing non-small cell lung adenocarcinoma (NSCLC) decreases treatment success. Cannabinoids emerge as drug candidates for NSCLC due to their anti-tumoral capabilities. We previously reported the controlled release of Arachidonylcyclopropylamide (ACPA) selectively targeting cannabinoid 1 (CB1) receptor in NSCLC cells in vitro. Hydrophobic polymers like polycaprolactone (PCL) offer prolonged circulation time and slower drug clearance which is suitable for hydrophobic molecules like ACPA. Thus, the extended circulation time with enhanced bioavailability and half-life of nanoparticular ACPA is crucial for its therapeutic performance in the tumor area. We assumed that a novel high technology-controlled release system increasing the bioavailability of ACPA compared to free ACPA could be transferred to the clinic when validated in vivo. Plasma profile of ACPA and ACPA-loaded PCL-based nanomedicine by LC-MS/MS and complete blood count (CBC) was assessed in wild-type Balb/c mice. Tumor growth in nanomedicine-applied NSCLC-induced athymic nude mice was assessed using bioluminescence imaging (BLI) and caliper measurements, histomorphometry, immunohistochemistry, TUNEL assay, and Western blot on days 7-21. Injectable NanoACPA increased its systemic exposure to tissues 5.5 times and maximum plasma concentration 6 times higher than free ACPA by substantially improving bioavailability. The potent effect of NanoACPA lasted for at least two days on ectopic NSCLC model through Akt/PI3K, Ras/MEK/Erk, and JNK pathways that diminished Ki-67 proliferative and promoted TUNEL apoptotic cell scores on days 7-21. The output reveals that NanoACPA platform could be a chemotherapeutic for NSCLC in the clinic following scale-up GLP/GMP-based phase trials, owing to therapeutic efficacy at a safe low dose window.

ART26.12, a novel fatty acid-binding protein 5 inhibitor, shows efficacy in multiple preclinical neuropathy models

BACKGROUND

Painful neuropathy is a pathological condition caused by numerous factors including diabetes, chemotherapy or cancer. ART26.12 is a novel fatty acid-binding protein 5 inhibitor, which our group showed could prevent and treat persistent pain in a preclinical model of oxaliplatin-induced peripheral neuropathy.

METHODS

In the current study, the efficacy of orally dosed ART26.12 was tested in multiple neuropathy models of different aetiology. Paw withdrawal threshold to von Frey monofilaments and latency to escape a cold plate were used as measurements of mechanical and cold sensitivity.

RESULTS

ART26.12 (25 and 50 mg/kg BID), dosed prior to the induction of paclitaxel-induced peripheral neuropathy (PIPN), reversed mechanical allodynia induced by paclitaxel in both male and female rats, and ART26.12 (50 mg/kg BID) prevented the induction of PIPN in female rats. ART26.12 (50 mg/kg BID) also had a protective effect on body weight in the PIPN model. ART26.12 (25 and 100 mg/kg BID) reversed mechanical allodynia when treating established streptozotocin-induced diabetic neuropathy in male rats. In a model of breast cancer-induced bone pain in female rats, ART26.12 (100 mg/kg BID) reversed mechanical allodynia within 1 h of dosing. In the same model, ART26.12 (25 mg/kg BID) reversed mechanical allodynia from day 4 of treatment.

CONCLUSION

Overall, these preclinical data suggest that ART26.12 is a safe and efficacious therapeutic drug for continued development towards the prevention and treatment of peripheral neuropathy.

SIGNIFICANCE STATEMENT

This work now shows that ART26.12, a novel and selective inhibitor of FABP5, can prevent and treat multiple preclinical models of peripheral neuropathy. Given its excellent safety profile, further work is warranted to develop ART26.12 as a potential therapeutic tool for pain management.

Efficacy of cannabis-based medicine in the treatment of Tourette syndrome: a systematic review and meta-analysis

BACKGROUND

Tourette syndrome (TS) is a neurodevelopmental disorder characterized by motor and phonic tics. It is a condition that affects between 0.3% and 0.7% of children, and its pathophysiology remains largely elusive. TS is associated with structural and functional alterations in corticostriatal circuits and neurochemical imbalances. Even though TS is currently incurable, there are established treatment options available, including behavioral therapy and neuroleptics. The use of cannabis-based medicine for tic management is an emerging therapeutic strategy, although its efficacy is still under investigation. It is hypothesized to interact with the endogenous cannabinoid system, but further research is required to ascertain its safety and effectiveness in TS.

AIM

In our systematic review and meta-analysis, we aim to assess the effectiveness of cannabis-based medicine in the treatment of TS.

METHODS

We searched PubMed, Cochrane, Scopus, and Web of Sciences until February 2024. We included clinical trials and cohort studies investigating the efficacy of cannabis-based medicine in the treatment of TS. Data extraction focused on baseline characteristics of the included studies and efficacy outcomes, including scores on the Yale Global Tic Severity Scale (YGTSS), Premonitory Urge for Tics Scale (PUTS), and Yale-Brown Obsessive Compulsive Scale (Y-BOCS). We conducted the meta-analysis using Review Manager version 5.4. software. We compared the measurements before and after drug intake using mean difference (MD) and 95% confidence interval (CI).

RESULTS

In total, 357 articles were identified for screening, with nine studies included in the systematic review and 3 in the meta-analysis. These studies involved 401 adult patients with TS treated with cannabis. YGTSS revealed a significant reduction in total scores (MD = -23.71, 95% CI [-43.86 to -3.55], P = 0.02), PUTS revealed a significant decrease in scores (MD = -5.36, 95% CI [-8.46 to -2.27], P = 0.0007), and Y-BOCS revealed no significant difference in score reduction (MD = -6.22, 95% CI [-12.68 to 0.23], P = 0.06).

CONCLUSION

The current study indicates promising and potentially effective outcomes with the use of cannabis-based medicine in mitigating the severity of tics and premonitory urges. However, there is a need for larger, placebo-controlled studies with more representative samples to validate these findings.

Impact of Medical Cannabis on Recovery from Playing-Related Musculoskeletal Disorders in Musicians: An Observational Cohort Study

INTRODUCTION

Playing-related musculoskeletal disorders (PRMDs) are musculoskeletal symptoms that interfere with the ability to play at the level a musician is accustomed to. Musicians have an 84% lifetime prevalence of PRMD. Many types of analgesia are inappropriate for this population due to their risks, but cannabidiol (CBD) has been shown to have anti-inflammatory properties and can reduce the perception of pain. Medical cannabis has also been shown to be safer than other analgesia in terms of serious adverse events. This study explores the impact of medical cannabis for PRMD on perceptions of pain and mental health outcomes.

METHODS

Participants (n = 204) completed questionnaires at baseline and six months: the Musculoskeletal Pain Intensity and Interference Questionnaire for Musicians (MPIIQM) and Depression, Anxiety and Stress Scale (DASS-21). Participants self-selected their group: non-cannabis users (n = 42), new medical cannabis users (n = 61), and long-term medical cannabis users (n = 101). Data were analyzed using paired t-tests for within-group and ANOVA for between-group differences.

RESULTS

At six months, there was no difference (p = 0.579) in cannabidiol dose between new (24.87 ± 12.86 mg) and long-term users (21.48 ± 12.50 mg). There was a difference in tetrahydrocannabinol (THC) dose (p = 0.003) between new (3.74 ± 4.22 mg) and long-term users (4.41 ± 5.18 mg). At six months, new cannabis users had a significant reduction in pain intensity as measured by The Musculoskeletal Pain Intensity and Interference Questionnaire for Musicians (MPIIQM40) (p = 0.002). Non-users (p = 0.035), new users (p = 0.002), and long-term cannabis users (p = 0.009) all had significant reductions in pain interference (MPIIQM50) at six months. At six months, non-cannabis (p = 0.022) and long-term cannabis users (p = 0.001) had an improvement in DASS-21. The change in pain intensity was the only difference between groups, F(2, 201) = 3.845, p = 0.023. This difference was between long-term (0.83 ± 0.79) and new users (-2.61 ± 7.15). No serious adverse events occurred, and a minority experienced tiredness, cough, and dry mouth.

DISCUSSION/CONCLUSIONS

This practice-based evidence demonstrated that the multidimensional approach to care provided by the Musicians' Clinics of Canada benefited all groups at six months. Medical cannabis significantly reduced pain intensity in new users of medical cannabis with PRMD, and all groups saw improvements in pain interference. In keeping with prior studies, medical cannabis seems to be effective at reducing perceptions of pain, including for PRMD. CBD/THC dosing was within guideline recommendations, and no patients experienced any serious adverse events. Limitations include multiple factors impacting patients' decisions to opt in or out of medical cannabis. These include cost, comorbidities, and disease chronicity. In conclusion, medical cannabis reduces pain intensity in new users, and when combined with a multidimensional approach to care, patients with PRMD can see improvements in pain as well as mental wellbeing.

Tolerability of High-Dose Oral Δ9-THC: Implications for Human Laboratory Study Design

Background: Δ9-tetrahydrocannabinol (THC), the primary intoxicating compound in cannabis, has been tested extensively in controlled administration human studies. Some studies require a high THC dose that may induce adverse events (AEs), such as those testing novel treatments for cannabinoid overdose. Although there are ethical concerns related to administering high THC doses, there is no systematic analysis on studies utilizing these doses. In this review, we examine studies that administered oral THC doses ≥30 mg ("high-dose THC"), focusing on reported tolerability, subjective effects, and pharmacokinetics (PK), with the objective to inform the design of future studies. Methods: A comprehensive PubMed search was performed to identify studies meeting pre-specified criteria. Results: Our search identified 27 publications from 17 high-dose oral THC laboratory studies, with single doses up to 90 mg and multiple doses up to 210 mg per day. The maximum plasma THC concentration (Cmax) appeared to increase in a dose-proportional manner over this dose range. All high-dose THC studies enrolled participants with previous cannabis experience, although current use ranged from nonusers to regular cannabis users. High-dose THC was generally well tolerated with transient mild to moderate AE, including nausea and vomiting, anxiety, paranoia, and sedation. There were occasional participant withdrawals due to AEs, but there were no serious AE. Participants with frequent cannabis use tolerated high-dose THC best. Conclusion: Although based on limited data, THC was generally adequately tolerated with single oral doses of at least 50 mg in a controlled laboratory setting in healthy participants with past cannabis experience.

Sex differences in acute delta-9-tetrahydrocannabinol (Δ9-THC) response and tolerance as a function of mouse strain

Cannabinoids are increasingly used to alleviate pain; however, tolerance to their antinociceptive effects, including those of delta-9-tetrahydrocannabinol (Δ9-THC), may limit their therapeutic utility. With more women than men using medical cannabis for pain relief, it is crucial to understand how sex influences cannabinoid-mediated antinociception and tolerance. Though studies in rats consistently find females are more sensitive to the acute antinociceptive effects of cannabinoids, our work with mice consistently finds the converse. The present study examined whether our observed sex differences in Δ9-THC-induced antinociception and tolerance are consistent across multiple mouse strains or are strain-dependent. Male and female C57BL/6J (B6), DBA/2, AKR, and CBA/J mice were assessed for differences in acute Δ9-THC-induced antinociception and hypothermia prior to and following seven days of once-daily Δ9-THC administration. Consistent with our previous findings, male B6 mice were more sensitive to the acute antinociceptive effects of Δ9-THC than female littermates, an effect which dissipated with age. B6 males had decreased cannabinoid expression in the PAG compared to females. While DBA and CBA female mice showed increased Δ9-THC-antinociception compared to male littermates at 30 and 10 mg/kg Δ9-THC, respectively, these differences were less pronounced at higher doses, revealing that dose of Δ9-THC may also be important. Overall, CBA mice were more sensitive to Δ9-THC-induced antinociception while AKR mice were less responsive. These studies highlight the therapeutic potential of Δ9-THC in pain management and underscore the importance of considering not only Δ9-THC dose as a function of sex, but potentially genetic differences when evaluating their clinical utility.