September 4, 2013
Dr Giuseppina Andreotti (scientific research council) and Dr Maria Vittoria Cubellis (coordinator), are working on the project Pharmacological chaperones to cure genetic diseases: development of drugs and identification of new targets (Telethon Foundation, Italy). In this interview, they will explain which are the problems they will tackle, how they will do so, and how it will help IRDiRC to reach its goals.
Interview of Dr Giuseppina Andreotti and Dr Maria Vittoria Cubellis
IRDiRC: What is the main problem that you will tackle?
Dr G. Andreotti and Dr M.V. Cubellis: We are interested in developing pharmacological chaperones (PC) to cure rare diseases. PC are small molecules which can be administered orally, reach difficult tissues such as the brain and have low cost. They stabilize proteins that are weakened by a mutation. We believe that these drugs have a vast field of application because the majority of mutations causing diseases affect protein stability and not functional sites.
IRDiRC: What is the concrete solution that you have selected? What are the steps? At what stage are you today?
Dr G. Andreotti and Dr M.V. Cubellis: We chose two model systems. The first is represented by Fabry disease, a lysosomal storage disorder. For this disease there are two therapies, the enzymatic replacement (ERT), which has already been approved, and the therapy with pharmacological chaperones, which is in clinical trial. The second system is represented by a disorder of glysosylation, a disease with no cure at present.
The first step of our job consists in the identification of the mutations which can be responsive to chaperones. It is important to realize that not all genotypes for any given disease can be treated with chaperones.
In the case of Fabry disease we have developed a method to predict in silico which mutations are responsive. We have described   and tested  this method and we have produced a user-friendly web-application to help clinician Choose Eligible Patients for the therapy with pharmacological chaperones (fabry_cep) . The user can introduce any missense/nonsense mutation in the coding sequence, learn whether it is has been tested and gain access to appropriate reference literature. In the absence of experimental data structural, functional and evolutionary analysis provides a prediction and the probability that a given mutation is responsive to pharmacological chaperons.
The second step of our job is represented by assays in vitro. Expressing and purifying specific mutants is expensive, therefore we are developing a method to test tiny amounts of un-purified proteins.
The third step consists in finding new chaperones for Fabry disease. The drug that is in clinical trial at present is administered to the patients every other day. The reason is that this molecule is an inhibitor of the enzymatic activity beside being a stabilizer. We believe that a second generation drug should be represented by stabilizers that are not inhibitors. We have a collaborator in Spain, Dr H. Pérez-Sánchez, Computer Science Department, Catholic University of Murcia (Spain) and we have started a project to seek such an improved drug.
As far as the disorder of glycosylation is concerned, we are at very preliminary stage. In fact, the enzyme responsible for the disease, phospho-mannomutaseII has been poorly characterized. Since the ultimate target of the drug is the protein product of the affected gene, we started characterizing phospho-mannomutaseII . We focused on the disease associated mutation encountered in Europe most frequently p.F119L/p.R141H-PMM2 .
Bioinformatics analysis is preliminary to all our experiments. This allows us to focus on experiments that have a high probability of success and cuts the costs. Moreover we try to find collaborations, both in terms of expertise and in terms of sharing equipments, this also cuts costs and time.
IRDiRC: What can the patients, the clinicians or other stakeholders expect at the end of the project?
Dr G. Andreotti and Dr M.V. Cubellis: At present we have already provided a tool to help clinicians choose the most appropriate therapy for Fabry patients (fabry_cep) . By the end of the project we could provide a new molecule which can be tested as a second generation pharmacological chaperone for Fabry disease.
We are checking the feasibility of the therapy with PC for the disorder of glysosylation type1A. We have tests in vitro and we are moving to tests in cellula.
IRDiRC: How is your project contributing to reaching the goals of IRDiRC by 2020?
Dr G. Andreotti and Dr M.V. Cubellis: We meet some of the IRDiRC objectives and in particular:
- Using in-silico medicine for improving disease management and prediction.
- Understanding disease.
IRDiRC: Where does this project position itself in this particular field at the international level?
Dr G. Andreotti and Dr M.V. Cubellis: Recent findings suggest that the approved therapy for Fabry disease might have a limited beneficial effect for patients and a high economical impact for health services . Some patients might be switched to the therapy with chaperones. Unfortunately more than 400 mutations have been described and only a percentage of them, which can be estimated around 50%, can be treated. Clinical trials should be carried in principle for every mutation , but this poses a big problem. For this reason our effort to predict in silico or to test in vitro mutants might have a big impact.
Therapies for the disorder of glycosylation are at their infancy and we believe that a precise characterization of damages at biochemical level is necessary.
Dr Giuseppina Andreotti and Dr Maria Vittoria Cubellis on behalf of Telethon Foundation, Italy.
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