The Current State of Drug Repurposing and Rare Diseases: An Interview with Paul Trippier

Paul Tripper is an Associate Professor of Medicinal Chemistry at the University of Nebraska Medical Center (UNMC, NE, USA) and an Editorial Board member of Future Drug Discovery. Here, he speaks to Managing Editor Francesca Lake about drug repurposing, focusing on the key challenges, its application to rare diseases and what we can look forward to in the future

Patient-Derived Induced Pluripotent Stem Cell Models for Phenotypic Screening in the Neuronal Ceroid Lipofuscinoses

Batten disease or neuronal ceroid lipofuscinosis (NCL) is a group of rare, fatal, inherited neurodegenerative lysosomal storage disorders. Numerous genes (CLN1-CLN8, CLN10-CLN14) were identified in which mutations can lead to NCL; however, the underlying pathophysiology remains elusive. Despite this, the NCLs share some of the same features and symptoms but vary in respect to severity and onset of symptoms by age. Some common symptoms include the progressive loss of vision, mental and motor deterioration, epileptic seizures, premature death, and in the rare adult-onset, dementia. Currently, all forms of NCL are fatal, and no curative treatments are available. Induced pluripotent stem cells (iPSCs) can differentiate into any cell type of the human body. Cells reprogrammed from a patient have the advantage of acquiring disease pathogenesis along with recapitulation of disease-associated phenotypes. They serve as practical model systems to shed new light on disease mechanisms and provide a phenotypic screening platform to enable drug discovery. Herein, we provide an overview of available iPSC models for a number of different NCLs. More specifically, we highlight findings in these models that may spur target identification and drug development

Aldo-Keto Reductases and Cancer Drug Resistance

Human aldo-keto reductases (AKRs) catalyze the NADPH-dependent reduction of carbonyl groups to alcohols for conjugation reactions to proceed. They are implicated in resistance to cancer chemotherapeutic agents either because they are directly involved in their metabolism or help eradicate the cellular stress created by these agents (e.g., reactive oxygen species and lipid peroxides). Furthermore, this cellular stress activates the Nuclear factor-erythroid 2 p45-related factor 2 (NRF2)-Kelch-like ECH-associated protein 1 pathway. As many human AKR genes are upregulated by the NRF2 transcription factor, this leads to a feed-forward mechanism to enhance drug resistance. Resistance to major classes of chemotherapeutic agents (anthracyclines, mitomycin, cis-platin, antitubulin agents, vinca alkaloids, and cyclophosphamide) occurs by this mechanism. Human AKRs also catalyze the synthesis of androgens and estrogens and the elimination of progestogens and are involved in hormonal-dependent malignancies. They are upregulated by antihormonal therapy providing a second mechanism for cancer drug resistance and/or syndergize the effects of existing drugs. SIGNIFICANCE STATEMENT: Aldo-keot reductases (AKRs) are overexpressed in a large number of human tumors and mediate resistance to cancer chemotherapeutics and antihormonal therapies. Existing drugs and new agents in development may surmount this resistance by acting as specific AKR isoforms or AKR pan-inhibitors to improve clinical outcome

Synthesis of Neurolysin Modulators for Stroke and Cancer Treatment

Neurolysin (Nln) is a neutral metalloendopeptidase, which is an enzyme that breaks down peptide bonds in amino acids whilst ultilizing a metal catalyst1. Nln inactivates several neuro/cerberotoxic neuropeptides such as neurotensin, substance P, and bradykinin2. These neuropeptides can cause harm to the brain as they respond to inflammation during an ischemic stroke3,4. The peptides generated by Nln are neuro/cerebroprotective which aids in its ability to protect the brain in an ischemic stroke victim2. The goal of our lab is to discover a potent neurolysin activator in order to develop a drug that protect victims from brain damage and disability following an ischemic stroke. To begin this process, our lab successfully designed, synthesized, and established the structure-activity relationships of several potential neurolysin activators via a preliminary neurolysin activation assay on several targeted compounds. Secondary amine analogs were created and synthesized to test their neurolysin activation potential. The goals of this experiment are to resynthesize these compounds to gather additional NMR and HPLC data and to optimize the reaction to obtain a pure compound with a substantial yield.https://digitalcommons.unmc.edu/surp2022/1007/thumbnail.jp

Investigating the Anti-tumorigenic Properties of Synthetic Inhibitors of B7-H3 in Group 3 Medulloblastoma

Medulloblastomas (MB) are devastating brain tumors originating in the cerebellum most commonly in children. There are four distinct subgroups of medulloblastoma: WNT (wingless), SHH (sonic hedgehog), group 3, and group 4. The most malignant tumors possess an aggressive phenotype characterized by c-Myc amplification and deletions to chromosome 17p; they belong to group 3. Prior investigations into the significance of genes on 17p revealed that miR-1253, which is found on locus 17p13.3, is significantly downregulated in medulloblastoma and has important tumor suppressive properties. Amongst its oncogenic targets is B7-H3 (CD276), a highly deregulated oncoprotein that attenuates the immune response to MB tumors. We chose to elucidate the oncogenic properties of B7-H3 in group 3 MB using synthetic inhibitors. After screening 100,000 different compounds for: 1) docking ability, 2) oral bioavailability, 3) potential CNS activity, and 4) number of metabolic side reactions, we selected two N-terminal inhibitors: B7-H3-Ni1 and B7-H3-Ni3. In HDMB03 cells (with c-Myc amplification and i17q), we found an IC50 of 3.7 M for B7-H3-Ni1 and no discernible effect of B7-H3-Ni3. We confirmed CD276 expression inhibition using B7-H3-Ni1 via Western blotting and concurrently noted elevations in cleaved PARP (apoptosis) and reduction in p-Akt (proliferation marker), providing us preliminary insights into the mechanism of inhibition. Notably, a remarkable decline in migration and wound healing and abrogation of colony formation were observed with B7-H3-Ni1. Collectively, our findings substantiate the inhibitory properties of B7-H3-Ni1 in vitro, potentially serving as a therapeutic agent for in vivo group 3 MB tumors.https://digitalcommons.unmc.edu/surp2021/1049/thumbnail.jp

Sex-specific Gene Expression in Flupirtine-Treated Cln3Δex7/8 Mouse Brain

Gene expression is a powerful tool to understand structure-function relationships in the nervous system. This study reports global gene expression changes induced by flupirtine in brain of male and female Cln3Δex7/8 mice, exposing potential flupirtine targets at the molecular level. Gene expression analysis of male and female Cln3Δex7/8 mouse brain was determined following oral administration of flupirtine for 14 weeks, using Mouse Genome 430 2.0 array Chips and an Affymetrix platform. Fifty-six genes in males and 79 in females were differentially expressed in flupirtine- versus vehicle-treated Cln3Δex7/8 mouse brain. Flupirtine altered several pathways in Cln3Δex7/8 mouse brain: apoptosis, the complement cascade, NF-kB, and p38α MAPK signaling pathways. Gene-gene network analysis highlighted networks and processes functionally pertinent to flupirtine treatment. These encompassed neurodegeneration, neuro-inflammation, and implicated neurological disorders such as Alzheimer and Parkinson disease. Flupirtine mediates its action in males and females through distinctive actionable targets in the same pathways. This work consolidates the groundwork for considering flupirtine as a treatment option in human CLN3 disease

Flupirtine Derivatives as Potential Treatment for the Neuronal Ceroid Lipofuscinoses

OBJECTIVE: Neuronal Ceroid Lipofuscinoses (NCL) are fatal inherited neurodegenerative diseases with established neuronal cell death and increased ceramide levels in brain, hence, a need for disease-modifying drug candidates, with potential to enhance growth, reduce apoptosis and lower ceramide in neuronal precursor PC12 cells and human NCL cell lines using enhanced flupirtine aromatic carbamate derivatives in vitro. METHODS: Aromatic carbamate derivatives were tested by establishing growth curves under pro-apoptotic conditions and activity evaluated by trypan blue and JC-1 staining, as well as a drop in pro-apoptotic ceramide in neuronal precursor PC12 cells following siRNA knockdown of the RESULTS: Retigabine, the benzyl-derivatized carbamate and an allyl carbamate derivative were neuroprotective in CLN3-defective PC12 cells and rescued CLN1-/CLN2-/CLN3-/CLN6-/CLN8 patient-derived lymphoblasts from diminished growth and accelerated apoptosis. All drugs decreased ceramide in CLN1-/CLN2-/CLN3-/CLN6-/CLN8 patient-derived lymphoblasts. Increased INTERPRETATION: These findings establish that compounds analogous to flupirtine demonstrate anti-apoptotic activity with potential for treatment of NCL disease and use of ceramide as a marker for these diseases

Exogenous Flupirtine as Potential Treatment for CLN3 Disease

CLN3 disease is a fatal neurodegenerative disorder affecting children. Hallmarks include brain atrophy, accelerated neuronal apoptosis, and ceramide elevation. Treatment regimens are supportive, highlighting the importance of novel, disease-modifying drugs. Flupirtine and its new allyl carbamate derivative (compound 6) confer neuroprotective effects in CLN3-deficient cells. This study lays the groundwork for investigating beneficial effects in Cln3Δex7/8 mice. WT/Cln3Δex7/8 mice received flupirtine/compound 6/vehicle for 14 weeks. Short-term effect of flupirtine or compound 6 was tested using a battery of behavioral testing. For flupirtine, gene expression profiles, astrogliosis, and neuronal cell counts were determined. Flupirtine improved neurobehavioral parameters in open field, pole climbing, and Morris water maze tests in Cln3Δex7/8 mice. Several anti-apoptotic markers and ceramide synthesis/degradation enzymes expression was dysregulated in Cln3Δex7/8 mice. Flupirtine reduced astrogliosis in hippocampus and motor cortex of male and female Cln3Δex7/8 mice. Flupirtine increased neuronal cell counts in male mice. The newly synthesized compound 6 showed promising results in open field and pole climbing. In conclusion, flupirtine improved behavioral, neuropathological and biochemical parameters in Cln3Δex7/8 mice, paving the way for potential therapies for CLN3 disease

Effects of antiplatelet therapy on stroke risk by brain imaging features of intracerebral haemorrhage and cerebral small vessel diseases: subgroup analyses of the RESTART randomised, open-label trial

Background Findings from the RESTART trial suggest that starting antiplatelet therapy might reduce the risk of recurrent symptomatic intracerebral haemorrhage compared with avoiding antiplatelet therapy. Brain imaging features of intracerebral haemorrhage and cerebral small vessel diseases (such as cerebral microbleeds) are associated with greater risks of recurrent intracerebral haemorrhage. We did subgroup analyses of the RESTART trial to explore whether these brain imaging features modify the effects of antiplatelet therapy

Boronic acids in medicinal chemistry: anticancer, antibacterial and antiviral applications

In 2003, bortezomib, a first-in-class therapeutic, gained approval from the US Federal Drug Administration for the treatment of relapsed multiple myeloma and mantle cell lymphoma. Approval in the UK, for multiple myeloma, followed in 2006. Bortezomib contains a boronic acid, a functional group that has become increasingly more commonplace within the medicinal chemistry literature. The introduction of this drug has sparked a renewed interest in the investigation of boronic acids as drugs for a wide range of diseases. This review will guide the reader through the most recent developments in this field, by considering in turn, the biological target's amenable to the action of boronic acids