Population-Based Characterization of the Pharmacokinetics and Food Effect of ANAVEX3-71, a Novel Sigma-1 Receptor and Allosteric M1 Muscarinic Receptor Agonist in Development for Treatment of Frontotemporal Dementia, Schizophrenia, and Alzheimer Disease

Pharmacokinetic (PK) data from 28 subjects who received 5-200-mg single ascending doses of ANAVEX3-71, formerly AF710B, were analyzed to characterize the PK of ANAVEX3-71 and its M8 metabolite. PK data from 12 subjects who received 160 mg ANAVEX3-71 under fed and fasted conditions were analyzed to characterize the effect of food on the PK of the drug and its M8 metabolite. PK was characterized using the standard 2-stage approach and the nonlinear mixed-effects modeling approach. Dose proportionality was determined using the power model. Two- and 3-compartment linear PK models were tested for the characterization of the PK of ANAVEX3-71 and its M8 metabolite. The PK of ANAVEX3-71 is linear, dose proportional, and time invariant. The drug is rapidly eliminated with a mean (standard deviation) apparent terminal elimination half-life of 3.56 (4.09) hours, while the M8 metabolite was eliminated with a mean (standard deviation) apparent terminal elimination half-life of 6.59 (1.64) hours. The population PK model was used to investigate the effects of covariates on the PK of ANAVEX3-71 and M8. Age, weight, and creatinine clearance were not explanatory of the variability in apparent clearance and apparent volume of the central compartment of ANAVEX3-71. Food had no effect on the PK of ANAVEX3-71 and its M8 metabolite.

Concentration-QTc Relationship from a Single Ascending Dose Study of ANAVEX3-71, a Novel Sigma-1 Receptor and Allosteric M1 Muscarinic Receptor Agonist in Development for the Treatment of Frontotemporal Dementia, Schizophrenia, and Alzheimer's Disease

This is the cardiodynamic evaluation of a single ascending dose study in healthy participants with the primary objective of assessing the effect of ANAVEX3-71, formerly AF710B, on ECG parameters. Twelve-lead ECGs were obtained at 3 time points within 1 hour prior to dosing to establish a baseline and then serially postdose. Concentration-QTc analysis of plasma concentrations of ANAVEX3-71 and metabolite M8 was conducted. ANAVEX3-71 at the studied doses did not have a clinically relevant effect on heart rate or on the PR and QRS intervals. ANAVEX3-71 alone was retained in the primary model due to small fit differences between models which included the metabolite M8. The estimated population slope of the concentration-QTcF relationship was small and slightly negative: -0.017 ms per µg/L, with a small treatment effect-specific intercept of -0.49 ms. An effect on the placebo-corrected, change-from-baseline QTc exceeding 10 ms can be excluded within the full observed ranges of plasma concentrations of ANAVEX3-71 and M8 up to ∼996 and ∼58 µg/L, respectively. The results from this cardiodynamic evaluation demonstrated that ANAVEX3-71 at single ascending doses of 5-200 mg had no clinically relevant effects on any of the studied ECG parameters.

Effects of the sigma-1 receptor agonist blarcamesine in a murine model of fragile X syndrome: neurobehavioral phenotypes and receptor occupancy

Fragile X syndrome (FXS), a disorder of synaptic development and function, is the most prevalent genetic form of intellectual disability and autism spectrum disorder. FXS mouse models display clinically-relevant phenotypes, such as increased anxiety and hyperactivity. Despite their availability, so far advances in drug development have not yielded new treatments. Therefore, testing novel drugs that can ameliorate FXS' cognitive and behavioral impairments is imperative. ANAVEX2-73 (blarcamesine) is a sigma-1 receptor (S1R) agonist with a strong safety record and preliminary efficacy evidence in patients with Alzheimer's disease and Rett syndrome, other synaptic neurodegenerative and neurodevelopmental disorders. S1R's role in calcium homeostasis and mitochondrial function, cellular functions related to synaptic function, makes blarcamesine a potential drug candidate for FXS. Administration of blarcamesine in 2-month-old FXS and wild type mice for 2 weeks led to normalization in two key neurobehavioral phenotypes: open field test (hyperactivity) and contextual fear conditioning (associative learning). Furthermore, there was improvement in marble-burying (anxiety, perseverative behavior). It also restored levels of BDNF, a converging point of many synaptic regulators, in the hippocampus. Positron emission tomography (PET) and ex vivo autoradiographic studies, using the highly selective S1R PET ligand [18F]FTC-146, demonstrated the drug's dose-dependent receptor occupancy. Subsequent analyses also showed a wide but variable brain regional distribution of S1Rs, which was preserved in FXS mice. Altogether, these neurobehavioral, biochemical, and imaging data demonstrates doses that yield measurable receptor occupancy are effective for improving the synaptic and behavioral phenotype in FXS mice. The present findings support the viability of S1R as a therapeutic target in FXS, and the clinical potential of blarcamesine in FXS and other neurodevelopmental disorders.

A precision medicine framework using artificial intelligence for the identification and confirmation of genomic biomarkers of response to an Alzheimer's disease therapy: Analysis of the blarcamesine (ANAVEX2-73) Phase 2a clinical study

INTRODUCTION

The search for drugs to treat Alzheimer's disease (AD) has failed to yield effective therapies. Here we report the first genome-wide search for biomarkers associated with therapeutic response in AD. Blarcamesine (ANAVEX2-73), a selective sigma-1 receptor (SIGMAR1) agonist, was studied in a 57-week Phase 2a trial (NCT02244541). The study was extended for a further 208 weeks (NCT02756858) after meeting its primary safety endpoint.

METHODS

Safety, clinical features, pharmacokinetic, and efficacy, measured by changes in the Mini-Mental State Examination (MMSE) and the Alzheimer's Disease Cooperative Study-Activities of Daily Living scale (ADCS-ADL), were recorded. Whole exome and transcriptome sequences were obtained for 21 patients. The relationship between all available patient data and efficacy outcome measures was analyzed with unsupervised formal concept analysis (FCA), integrated in the Knowledge Extraction and Management (KEM) environment.

RESULTS

Biomarkers with a significant impact on clinical outcomes were identified at week 57: mean plasma concentration of blarcamesine (slope MMSE:P < .041), genomic variants SIGMAR1 p.Gln2Pro (ΔMMSE:P < .039; ΔADCS-ADL:P < .063) and COMT p.Leu146fs (ΔMMSE:P < .039; ΔADCS-ADL:P < .063), and baseline MMSE score (slope MMSE:P < .015). Their combined impact on drug response was confirmed at week 148 with linear mixed effect models.

DISCUSSION

Confirmatory Phase 2b/3 clinical studies of these patient selection markers are ongoing. This FCA/KEM analysis is a template for the identification of patient selection markers in early therapeutic development for neurologic disorders.

ANAVEX®2-73 (blarcamesine), a Sigma-1 receptor agonist, ameliorates neurologic impairments in a mouse model of Rett syndrome

Rett syndrome (RTT) is a severe neurodevelopmental disorder that is associated in most cases with mutations in the transcriptional regulator MECP2. At present, there are no effective treatments for the disorder. Despite recent advances in RTT genetics and neurobiology, most drug development programs have focused on compounds targeting the IGF-1 pathway and no pivotal trial has been completed as yet. Thus, testing novel drugs that can ameliorate RTT's clinical manifestations is a high priority. ANAVEX2-73 (blarcamesine) is a Sigma-1 receptor agonist and muscarinic receptor modulator with a strong safety record and preliminary evidence of efficacy in patients with Alzheimer's disease. Its role in calcium homeostasis and mitochondrial function, cellular functions that underlie pathological processes and compensatory mechanisms in RTT, makes blarcamesine an intriguing drug candidate for this disorder. Mice deficient in MeCP2 have a range of physiological and neurological abnormalities that mimic the human syndrome. We tested blarcamesine in female heterozygous mice carrying one null allele of Mecp2 (HET) using a two-tier approach, with age-appropriate tests. Administration of the drug to younger and older adult mice resulted in improvement in multiple motor, sensory, and autonomic phenotypes of relevance to RTT. The latter included motor coordination and balance, acoustic and visual responses, hindlimb clasping, and apnea in expiration. In line with previous animal and human studies, blarcamesine also showed a good safety profile in this mouse model of RTT. Clinical studies in RTT with blarcamesine are ongoing.