Nathalie Cholet

Polytherapy with a combination of three repurposed drugs (PXT3003) down-regulates Pmp22 over-expression and improves myelination, axonal and functional parameters in models of CMT1A neuropathy

Charcot-Marie-Tooth disease type 1A (CMT1A) is the most common inherited sensory and motor peripheral neuropathy. It is caused by PMP22 overexpression which leads to defects of peripheral myelination, loss of long axons, and progressive impairment then disability. There is no treatment available despite observations that monotherapeutic interventions slow progression in rodent models. We thus hypothesized that a polytherapeutic approach using several drugs, previously approved for other diseases, could be beneficial by simultaneously targeting PMP22 and pathways important for myelination and axonal integrity. A combination of drugs for CMT1A polytherapy was chosen from a group of authorised drugs for unrelated diseases using a systems biology approach, followed by pharmacological safety considerations. Testing and proof of synergism of these drugs were performed in a co-culture model of DRG neurons and Schwann cells derived from a Pmp22 transgenic rat model of CMT1A. Their ability to lower Pmp22 mRNA in Schwann cells relative to house-keeping genes or to a second myelin transcript (Mpz) was assessed in a clonal cell line expressing these genes. Finally in vivo efficacy of the combination was tested in two models: CMT1A transgenic rats, and mice that recover from a nerve crush injury, a model to assess neuroprotection and regeneration. Combination of (RS)-baclofen, naltrexone hydrochloride and D-sorbitol, termed PXT3003, improved myelination in the Pmp22 transgenic co-culture cellular model, and moderately down-regulated Pmp22 mRNA expression in Schwannoma cells. In both in vitro systems, the combination of drugs was revealed to possess synergistic effects, which provided the rationale for in vivo clinical testing of rodent models. In Pmp22 transgenic CMT1A rats, PXT3003 down-regulated the Pmp22 to Mpz mRNA ratio, improved myelination of small fibres, increased nerve conduction and ameliorated the clinical phenotype. PXT3003 also improved axonal regeneration and remyelination in the murine nerve crush model. Based on these observations in preclinical models, a clinical trial of PTX3003 in CMT1A, a neglected orphan disease, is warranted. If the efficacy of PTX3003 is confirmed, rational polytherapy based on novel combinations of existing non-toxic drugs with pleiotropic effects may represent a promising approach for rapid drug development.

Combining two repurposed drugs as a promising approach for Alzheimer's disease therapy

Alzheimer disease (AD) represents a major medical problem where mono-therapeutic interventions demonstrated only a limited efficacy so far. We explored the possibility of developing a combinational therapy that might prevent the degradation of neuronal and endothelial structures in this disease. We argued that the distorted balance between excitatory (glutamate) and inhibitory (GABA/glycine) systems constitutes a therapeutic target for such intervention. We found that a combination of two approved drugs – acamprosate and baclofen – synergistically protected neurons and endothelial structures in vitro against amyloid-beta (Aβ) oligomers. The neuroprotective effects of these drugs were mediated by modulation of targets in GABA/glycinergic and glutamatergic pathways. In vivo, the combination alleviated cognitive deficits in the acute Aβ25–35 peptide injection model and in the mouse mutant APP transgenic model. Several patterns altered in AD were also synergistically normalised. Our results open up the possibility for a promising therapeutic approach for AD by combining repurposed drugs.

Combination of acamprosate and baclofen as a promising therapeutic approach for Parkinson's disease.

Parkinson’s disease (PD) is a progressive neurodegenerative disorder characterised by the loss of dopaminergic nigrostriatal neurons but which involves the loss of additional neurotransmitter pathways. Mono- or polytherapeutic interventions in PD patients have declining efficacy long-term and no influence on disease progression. The systematic analysis of available genetic and functional data as well as the substantial overlap between Alzheimer’s disease (AD) and PD features led us to repurpose and explore the effectiveness of a combination therapy (ABC) with two drugs – acamprosate and baclofen – that was already effective in AD animal models, for the treatment of PD. We showed in vitro that ABC strongly and synergistically protected neuronal cells from oxidative stress in the oxygen and glucose deprivation model, as well as dopaminergic neurons from cell death in the 6-hydroxydopamine (6-OHDA) rat model. Furthermore, we showed that ABC normalised altered motor symptoms in vivo in 6-OHDA-treated rats, acting by protecting dopaminergic cell bodies and their striatal terminals. Interestingly, ABC also restored a normal behaviour pattern in lesioned rats suggesting a symptomatic effect, and did not negatively interact with L-dopa. Our results demonstrate the potential value of combining repurposed drugs as a promising new strategy to treat this debilitating disease.

PXT864 COMBINATION RESTORES COGNITIVE DEFICITS OF ALZHEIMER’S MICE, EVEN IN ANIMALS WITH ADVANCED DISEASE THAT LOST RESPONSIVENESS TO DONEPEZIL

after treatment. Student t-test was used to compare the different groups of animals. Animals were visually and histologically inspected for tumor formation. Results: Treatment of eSCs and mSCs by a less-invasive intravenous route in the MPTP PD rodent model provided augmentation in motor abilities at early (10 days post-treatment) and later (3 months post-treatment) time points. Also, this treatment was deemed to be safe from teratomas. Conclusions: Motor impairment observed in MPTP-induced PD mice ameliorates after the treatment with NPs, and this is more evident several days after the therapy. Therefore, peripheral administration of NPs could be a promising therapy to treat motor impairment associated to PD.

A COMBINATION OF ACAMPROSATE AND BACLOFEN (PXT864) SYNERGIZES WITH STANDARDS OF CARE FOR THE TREATMENT OF ALZHEIMER’S DISEASE

Background:Enhancing the efficacy of drugs targeting cognitive decline in Alzheimer disease (AD), together with improving their safety, has been a long-term goal of therapeutic development. Currently approved standards of care (SOCs) exhibit transient efficacy and their use is accompanied by undesirable side effects. Thus, drug combination therapies, particularly those applying low doses, may represent next generation therapies for AD. Methods:We previously demonstrated the synergistic effectiveness of a combination therapy (known as PXT864) consisting of two repurposed drugs – acamprosate and baclofen – in AD models. As patients are usually treated with a SOC, we investigated whether the efficacy of these SOCs at inactive doses is improved by combining them with low or inactive doses of PXT864. To this end, we assessed the efficacy of PXT864 combined with the SOCs, donepezil or memantine, on different cellular and behavioral endpoints in an in vitro neuronal primary culture model intoxicated with oligomeric b-amyloid peptides (Ab), and an in vivo intracebroventricular Ab-injection mouse model. Results:We found that tri-therapy with PXT864+donepezil or PXT864+memantine synergistically protected neuronal cells against Ab toxicity with a higher protective effect than the individual drugs alone. In AD model animals, doses of individual drugs selected for their inactivity, and binary combinations of such doses of individual drugs, were totally ineffective whereas the tri-therapeutic combination synergistically alleviated cognitive deficits. Conclusions:These findings highlight the value of using repurposed drugs combined with low doses of existing SOC therapeutics, and emphasize the value of network pharmacology approach that allows to discover combinations with new mechanisms of action.