Gaucher disease is a genetic condition caused by mutations in the GBA gene and the resulting deficiency in the beta-glucocerebrosidase enzyme for which this gene encodes.
The current treatments available for Gaucher disease do not address the underlying cause of the disease, but help manage its symptoms. But there are several experimental treatments being developed to tackle the cause of the disease and provide a permanent solution.
Gene therapy
Gene therapy is an emerging field of therapeutics designed to treat a disease by either replacing the faulty or missing gene with a healthy one or “silencing” a gene that may be causing problems. Gene therapy for Gaucher disease uses the first approach.
Three experimental gene therapies for Gaucher disease are in various stages of development. They are FLT-200 by Freeline Therapeutics, AVR-RD-02 by Avrobio and AAV9-GBA by University College London and Apollo Therapeutics.
All three aim to deliver a healthy copy of the GBA gene to the cells using genetically modified viruses that are harmless. FLT-200 and AAV9-GBA use a modified adeno-associated virus for gene delivery; AVR-RD-02 uses a lentiviral vector to carry the healthy GBA gene to its target cells.
Small-molecule chaperone therapy
A new approach to restoring beta-glucocerebrosidase activity in patients with Gaucher disease is through the help of small molecules that serve as chaperones. Proper folding of a protein is essential for its correct functioning. Chaperones are small molecules that guide this folding process.
Ambroxol is a small molecule chaperone that improves the folding of the beta-glucocerebrosidase enzyme and enhances its activity. A recent study showed that ambroxol activity may be dependent on the type of GBA mutation and the cell type. A new Phase 2 study (NCT03950050) is evaluating the efficacy of ambroxol in type 1 Gaucher disease patients who did not respond well to enzyme replacement therapy. The study aims to enroll 60 participants, ages 18 to 75, in Israel.
Arimoclomol is a chaperone therapy candidate being developed by Orphazyme. Arimoclomol does not directly correct the folding of beta-glucocerebrosidase. Instead, it triggers the production of a natural chaperone called heat-shock protein 70 (HSP70), which helps the enzyme fold and function correctly and clear the buildup of glucocerebroside. A Phase 2 clinical trial (NCT03746587) is assessing three different oral doses of Arimoclomol in patients with type 1 and type 3 Gaucher disease. The trial is recruiting up to 40 participants ages 4–60 in India.
Two small molecules, NCGC758 and NCGC607, have shown promising results in increasing beta-glucocerebrosidase activity and lowering the accumulation of glucocerebroside when tested in cells grown in the laboratory.
Stem cell therapy
Stem cell therapy is a type of regenerative medicine approach in which damaged cells are replaced by a specific type of stem cells to repair the damaged tissue. Progressive neurodegeneration, or breakdown, of cells and tissues in the brain is seen in patients with Gaucher disease. Stem cell therapy research to replenish these dead cells and slow neurodegeneration is underway.
Researchers from Cincinnati Children’s Hospital Medical Center recently tested the efficacy of stem cell transplantation to regenerate brain tissues and improve function in a mouse model of Gaucher disease. The team transplanted neural progenitor cells derived from induced pluripotent stem cells (iPSCs) into the mice through their veins (intravenously). Neural progenitor cells are a type of brain cells that become nerve cells and other cells in the brain and spinal cord. The transplantation was successful as observed by the presence of these cells in different parts of the mouse brain. Neurodegeneration and inflammation were reduced in the transplanted regions of the brain. The mice also lived longer, indicating a high potential for stem cell therapy in treating Gaucher disease.
Gene therapy, in combination with stem cell therapy, is another approach being evaluated to treat Gaucher disease. Stem cells obtained from patients are modified in the laboratory using gene therapy vectors, as in the case of AAV-RD-02, to express healthy, functional copies of the GBA gene. The modified stem cells are grown in the laboratory first to increase their numbers, then reintroduced into the patient. Preclinical studies in mouse models using this approach have shown promising results.
Immunotherapy
A recent study showed that a small protein called C5aR1 promotes the activation of the pro-inflammatory molecule C5a following glucocerebroside accumulation in Gaucher disease patients. C5a triggers inflammation and causes organ and tissue damage. In a mouse model of Gaucher disease, the inhibition of C5a was able to protect the mice from developing an inflammatory response and cleared accumulation of glucocerebroside from the body, improving chances of survival. Based on these findings, researchers plan to test the anti-C5 monoclonal antibody therapy Soliris (eculizumab) by Alexion as a potential therapeutic candidate for Gaucher disease.
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