Identification of 5-HT2A receptor signaling pathways associated with psychedelic potential

Serotonergic psychedelics possess considerable therapeutic potential. Although 5-HT2A receptor activation mediates psychedelic effects, prototypical psychedelics activate both 5-HT2A-Gq/11 and β-arrestin2 transducers, making their respective roles unclear. To elucidate this, we develop a series of 5-HT2A-selective ligands with varying Gq efficacies, including β-arrestin-biased ligands. We show that 5-HT2A-Gq but not 5-HT2A-β-arrestin2 recruitment efficacy predicts psychedelic potential, assessed using head-twitch response (HTR) magnitude in male mice. We further show that disrupting Gq-PLC signaling attenuates the HTR and a threshold level of Gq activation is required to induce psychedelic-like effects, consistent with the fact that certain 5-HT2A partial agonists (e.g., lisuride) are non-psychedelic. Understanding the role of 5-HT2A Gq-efficacy in psychedelic-like psychopharmacology permits rational development of non-psychedelic 5-HT2A agonists. We also demonstrate that β-arrestin-biased 5-HT2A receptor agonists block psychedelic effects and induce receptor downregulation and tachyphylaxis. Overall, 5-HT2A receptor Gq-signaling can be fine-tuned to generate ligands distinct from classical psychedelics.

Safety and efficacy of arimoclomol for inclusion body myositis: a multicentre, randomised, double-blind, placebo-controlled trial

BACKGROUND

Inclusion body myositis is the most common progressive muscle wasting disease in people older than 50 years, with no effective drug treatment. Arimoclomol is an oral co-inducer of the cellular heat shock response that was safe and well-tolerated in a pilot study of inclusion body myositis, reduced key pathological markers of inclusion body myositis in two in-vitro models representing degenerative and inflammatory components of this disease, and improved disease pathology and muscle function in mutant valosin-containing protein mice. In the current study, we aimed to assess the safety, tolerability, and efficacy of arimoclomol in people with inclusion body myositis.

METHODS

This multicentre, randomised, double-blind, placebo-controlled study enrolled adults in specialist neuromuscular centres in the USA (11 centres) and UK (one centre). Eligible participants had a diagnosis of inclusion body myositis fulfilling the European Neuromuscular Centre research diagnostic criteria 2011. Participants were randomised (1:1) to receive either oral arimoclomol 400 mg or matching placebo three times daily (1200 mg/day) for 20 months. The randomisation sequence was computer generated centrally using a permuted block algorithm with randomisation numbers masked to participants and trial staff, including those assessing outcomes. The primary endpoint was the change from baseline to month 20 in the Inclusion Body Myositis Functional Rating Scale (IBMFRS) total score, assessed in all randomly assigned participants, except for those who were randomised in error and did not receive any study medication, and those who did not meet inclusion criteria. Safety analyses included all randomly assigned participants who received at least one dose of study medication. This trial is registered with ClinicalTrials.gov, number NCT02753530, and is completed.

FINDINGS

Between Aug 16, 2017 and May 22, 2019, 152 participants with inclusion body myositis were randomly assigned to arimoclomol (n=74) or placebo (n=78). One participant was randomised in error (to arimoclomol) but not treated, and another (assigned to placebo) did not meet inclusion criteria. 150 participants (114 [76%] male and 36 [24%] female) were included in the efficacy analyses, 73 in the arimoclomol group and 77 in the placebo group. 126 completed the trial on treatment (56 [77%] and 70 [90%], respectively) and the most common reason for treatment discontinuation was adverse events. At month 20, mean IBMFRS change from baseline was not statistically significantly different between arimoclomol and placebo (-3·26, 95% CI -4·15 to -2·36 in the arimoclomol group vs -2·26, -3·11 to -1·41 in the placebo group; mean difference -0·99 [95% CI -2·23 to 0·24]; p=0·12). Adverse events leading to discontinuation occurred in 13 (18%) of 73 participants in the arimoclomol group and four (5%) of 78 participants in the placebo group. Serious adverse events occurred in 11 (15%) participants in the arimoclomol group and 18 (23%) in the placebo group. Elevated transaminases three times or more of the upper limit of normal occurred in five (7%) participants in the arimoclomol group and one (1%) in the placebo group. Tubulointerstitial nephritis was observed in one (1%) participant in the arimoclomol group and none in the placebo group.

INTERPRETATION

Arimoclomol did not improve efficacy outcomes, relative to placebo, but had an acceptable safety profile in individuals with inclusion body myositis. This is one of the largest trials done in people with inclusion body myositis, providing data on disease progression that might be used for subsequent clinical trial design.

FUNDING

US Food and Drug Administration Office of Orphan Products Development and Orphazyme.

Identification of 5-HT2A Receptor Signaling Pathways Responsible for Psychedelic Potential

Serotonergic psychedelics possess considerable therapeutic potential. Although 5-HT2A receptor activation mediates psychedelic effects, prototypical psychedelics activate both 5-HT2A-Gq/11 and β-arrestin2 signaling, making their respective roles unclear. To elucidate this, we developed a series of 5-HT2A-selective ligands with varying Gq efficacies, including β-arrestin-biased ligands. We show that 5-HT2A-Gq but not 5-HT2A-β-arrestin2 efficacy predicts psychedelic potential, assessed using head-twitch response (HTR) magnitude in male mice. We further show that disrupting Gq-PLC signaling attenuates the HTR and a threshold level of Gq activation is required to induce psychedelic-like effects, consistent with the fact that certain 5-HT2A partial agonists (e.g., lisuride) are non-psychedelic. Understanding the role of 5-HT2A-Gq efficacy in psychedelic-like psychopharmacology permits rational development of non-psychedelic 5-HT2A agonists. We also demonstrate that β-arrestin-biased 5-HT2A receptor agonists induce receptor downregulation and tachyphylaxis, and have an anti-psychotic-like behavioral profile. Overall, 5-HT2A receptor signaling can be fine-tuned to generate ligands with properties distinct from classical psychedelics.

Phase 2 trial in acetylcholine receptor antibody-positive myasthenia gravis of transition from intravenous to subcutaneous immunoglobulin: The MGSCIg study

BACKGROUND AND PURPOSE

Data on maintenance therapy with subcutaneous immunoglobulin (SCIg) in myasthenia gravis (MG) are limited. We report on transitioning acetylcholine receptor (AChR) antibody-positive (Ab+) MG patients on stable intravenous immunoglobulin (IVIg) regimens as part of routine clinical care to SCIg 1:1.2.

METHODS

This multicenter North American open-label prospective investigator-initiated study had two components: the IVIg Stabilization Period (ISP) enrolling patients already on IVIg as part of routine clinical care (Weeks -10 to -1), followed by transition of stable MG subjects to SCIg in the Experimental Treatment Period (ETP; Weeks 0 to 12). We hypothesized that >65% of patients entering the ETP would have a stable Quantitative Myasthenia Gravis (QMG) score from Week 0 to Week 12. Secondary outcome measures included other efficacy measures, safety, tolerability, IgG levels, and treatment satisfaction.

RESULTS

We recruited 23 patients in the ISP, and 22 entered the ETP. A total of 12 subjects (54.5%) were female, and 18 (81.8%) were White, with mean age 51.4 ± 17 years. We obtained Week 12 ETP QMG data on 19 of 22; one subject withdrew from ETP owing to clinical deterioration, and two subjects withdrew due to dislike of needles. On primary analysis, 19 of 22 participants (86.4%, 95% confidence interval = 0.72-1.00) were treatment successes using last observation carried forward (p = 0.018). Secondary efficacy measures supported MG stability. SCIg was safe and well tolerated, and IgG levels were stable. Treatment satisfaction was comparable between ISP and ETP.

CONCLUSIONS

MG patients on IVIg as part of their routine clinical care remained stable on monthly IVIg dosage, and most maintained similar disease stability on SCIg.

Methotrexate Polyglutamation in a Myasthenia Gravis Clinical Trial

INTRODUCTION

Methotrexate (MTX) is an immunosuppressive and anti-inflammatory drug used to treat rheumatoid arthritis (RA) and other autoimmune conditions. MTX is transported into cells, where glutamate moieties are added and is retained as methotrexate polyglutamates (MTXPGs). In the RA literature, it has been reported that the degree of polyglutamation correlates with the anti-inflammatory effect of MTX in RA. There are no prior studies evaluating the relationship between MTXPGs and myasthenia gravis (MG) outcome measures. The objective of this study was to assess the correlation between methotrexate (MTX) polyglutamates (MTXPGs) with Myasthenia Gravis (MG) outcome measures.

METHODS

An analysis was done of blood drawn from patients enrolled in the 12-month randomized, placebo-controlled study of MTX in MG study. Red blood cell MTXPGs were measured via ultra-performance liquid chromatography and tandem mass spectrometry. MTXPG was correlated to MG outcome measures using Spearman Correlation Coefficient. A two-group t-test was used to determine the difference in MTXPG based on clinical outcome responder definitions.

RESULTS

Twenty-one polyglutamate samples were analyzed of subjects on MTX while eight samples were analyzed from subjects on placebo. Pentaglutamate had the strongest correlation with the MG-ADL (0.99), while tetraglutamate had the strongest correlation with the QMG (0.54). Triglutamate had the strongest correlation with MGC (0.76).

CONCLUSION

There were variable correlations between MTXPG_1-5 and MG outcomes (rho range: 0.08 to 0.99). There are strong correlations between MTXPG and the MG-ADL, QMG, and MGC. Long chain methotrexate polyglutamates correlate better with MG outcomes.

A Randomized, Double-Blinded, Placebo-Controlled, Cross Over Study Evaluating the Efficacy and Safety of Timolol Ophthalmic Solution as an Acute Treatment of Migraine

INTRODUCTION

Daily oral beta-adrenoreceptor antagonist has been shown to be effective in preventing migraine headaches. Timolol 0.5% ophthalmic solution is a non-selective beta-adrenoreceptor antagonist, where the primary use is for glaucoma. There have been case reports that timolol is effective in aborting or improving an acute migraine headache. The objective of this study was to assess the efficacy (decrease of ≥ 50% in pain scale at 120 minutes) of timolol 0.5% ophthalmic solution compared to placebo in acute treatment of migraine headache.

METHODS

We performed a randomized, double-blind, crossover, placebo-controlled, study. Study entry criteria required subjects to have one to eight migraine episodes per month. The primary outcome was comparison of the change in a visual analog pain scale (VAS) at 120 minutes after taking the study medication. Study subjects were given a pain scale with a range of 1 (no pain) to 10 (most severe pain) to complete after onset of migraine but before administration of study drops and 120 minutes after administration of study drops. Improvement was defined as a ≥ 50% decrease in pain scale.

RESULTS

Nineteen subjects completed the study and were used for analysis. The primary outcome changes in pain scale, 120 minutes after dose, showed a similar decrease for placebo and drug with a slightly wider 95% CI for placebo. Six subjects in each arm experienced a ≥ 50% decrease in pain scale.

CONCLUSION

These results support that timolol 0.5% ophthalmic solution is not an efficacious treatment for acute migraine headache.

Methotrexate Polyglutamation in a Myasthenia Gravis Clinical Trial

Introduction. Methotrexate (MTX) is an immunosuppressive and anti-inflammatory drug used to treat rheumatoid arthritis (RA) and other autoimmune conditions. MTX is transported into cells, where glutamate moieties are added and is retained as methotrexate polyglutamates (MTXPGs). In the RA literature, it has been reported that the degree of polyglutamation correlates with the anti-inflammatory effect of MTX in RA. There are no prior studies evaluating the relationship between MTXPGs and myasthenia gravis (MG) outcome measures. The objective of this study was to assess the correlation between methotrexate (MTX) polyglutamates (MTXPGs) with Myasthenia Gravis (MG) outcome measures. Methods.xAn analysis was done of blood drawn from patients enrolled in the 12-month randomized, placebo-controlled study of MTX in MG study. Red blood cell MTXPGs were measured via ultraperformance liquid chromatography and tandem mass spectrometry. MTXPG was correlated to MG outcome measures using Spearman Correlation Coefficient. A two-group t-test was used to determine the difference in MTXPG based on clinical outcome responder definitions. Results. Twenty-one polyglutamate samples were analyzed of subjects on MTX while eight samples were analyzed from subjects on placebo. Pentaglutamate had the strongest correlation with the MG-ADL (0.99), while tetraglutamate had the strongest correlation with the QMG (0.54). Triglutamate had the strongest correlation with MGC (0.76). Conclusion. There were variable correlations between MTXPG1-5 and MG outcomes (rho range: 0.08 to 0.99). There are strong correlations between MTXPG and the MG-ADL, QMG, and MGC. Long chain methotrexate polyglutamates correlate better with MG outcomes.

Improving homology modeling of G-protein coupled receptors through multiple-template derived conserved inter-residue interactions

Evidenced by the three-rounds of G-protein coupled receptors (GPCR) Dock competitions, improving homology modeling methods of helical transmembrane proteins including the GPCRs, based on templates of low sequence identity, remains an eminent challenge. Current approaches addressing this challenge adopt the philosophy of "modeling first, refinement next". In the present work, we developed an alternative modeling approach through the novel application of available multiple templates. First, conserved inter-residue interactions are derived from each additional template through conservation analysis of each template-target pairwise alignment. Then, these interactions are converted into distance restraints and incorporated in the homology modeling process. This approach was applied to modeling of the human β2 adrenergic receptor using the bovin rhodopsin and the human protease-activated receptor 1 as templates and improved model quality was demonstrated compared to the homology model generated by standard single-template and multiple-template methods. This method of "refined restraints first, modeling next", provides a fast and complementary way to the current modeling approaches. It allows rational identification and implementation of additional conserved distance restraints extracted from multiple templates and/or experimental data, and has the potential to be applicable to modeling of all helical transmembrane proteins.

Molecular dynamics simulations of detonation instability

After making modifications to the reactive empirical bond-order potential for molecular dynamics (MD) of Brenner et al. [Phys. Rev. Lett.70, 2174 (1993); 76, 2202(E) (1996)] in order to make the model behave in a more conventional manner, we discover that the updated model exhibits detonation instability, a first for MD. The instability is analyzed in terms of the accepted theory.

Interaction potential for atomic simulations of conventional high explosives

In an effort to develop a chemically reactive interaction potential suitable for application to the study of conventional, organic explosives, we have modified the diatomic AB potential of Brenner et al. [Phys. Rev. Lett. 70, 2174 (1993); 76, 2202(E) (1996)] such that it exhibits improved detonation characteristics. In particular, equilibrium molecular dynamics (MD) calculations of the modified potential demonstrate that the detonation products have an essentially diatomic, rather than polymeric, composition and that the detonation Hugoniot has the classic, concave-upward form. Nonequilibrium MD calculations reveal the separation of scales between chemical and hydrodynamic effects essential to the Zel'dovitch, von Neumann, and Döring theory.

Influence of interatomic bonding potentials on detonation properties

The dependences of the macroscopic detonation properties of a two-dimensional (2D) diatomic (AB) molecular system on the fundamental molecular properties were investigated. This includes examining the detonation velocity, reaction zone thickness, and critical width as functions of the exothermicity (Q) of the gas-phase reaction [AB --> (1/2)(A(2) + B(2))] and the gas-phase dissociation energy (D(e)(AB)) for AB --> A + B . Following previous work, molecular dynamics (MD) simulations with a reactive empirical bond-order potential were used to characterize the shock-induced response of a diatomic AB molecular solid, which exothermically reacts to produce A2 and B2 gaseous products. Nonequilibrium MD simulations reveal that there is a linear dependence between the square of the detonation velocity and both of these molecular parameters. The detonation velocities were shown to be consistent with the Chapman-Jouguet (CJ) model, demonstrating that these dependences arise from how the equation of state of the products and reactants are affected. Equilibrium MD simulations of microcanonical ensembles were used to determine the CJ states for varying Q 's, and radial distribution functions characterize the atomic structure. The character of this material near the CJ conditions was found to be somewhat unusual, consisting of polyatomic clusters rather than discrete molecular species. It was also found that there was a minimum value of Q and a maximum value of (D(e)(AB)) for which a pseudo-one-dimensional detonation could not be sustained. The reaction zone of this material was characterized under both equilibrium (CJ) and transient (underdriven) conditions. The basic structure is consistent with the Zeldovich-von Neumann-Döring model, with a sharp shock rise and a reaction zone that extends to 200-300 Angstrom. The underdriven systems show a buildup process which requires an extensive time to approach equilibrium conditions. The rate stick failure diameter (critical width in 2D) was also found to depend on Q and (D(e)(AB)). The dependence on Q could be explained in terms of the reaction zone properties.