Sanfilippo is caused by the deficiency of one of the enzymes required to degrade a complex sugar called heparan sulfate. This heparan sulfate then accumulates in all tissues (especially in the brain) causing damage.

The most promising therapeutic approaches for the treatment of Sanfilippo Syndrome are based on the replacement of either the missing enzyme (enzyme replacement therapy) or the gene responsible for making that enzyme (gene therapy). Maintaining high enough levels of the replaced enzyme, especially in the brain, is proving to be a challenge for these approaches. 

In this project, the researchers will search for enzymes that are able to degrade heparan sulfate even more efficiently than the natural enzyme present in people without Sanfilippo. These are called ‘super active’ enzymes and if successful, could increase the effectiveness of gene and enzyme replacement therapies and/or lower the dose required, thus improving their safety. This approach has been successful for conditions such as haemophilia.

The enzyme missing in Sanfilippo Syndrome Type A – sulfamidase – will be the target in this project and if successful, this approach could be applied to the other subtypes. The researchers will artificially produce in the lab thousands of variants of the sulfamidase enzyme, each with small random changes to its structure. Sophisticated high throughput screening methods will then be used to select potential ‘super active’ enzymes.

“Therapies that treat the root cause of Sanfilippo – gene therapy and enzyme replacement therapy – are so promising, but there is still more work to be done to optimise them for maximum benefit for patients. This project is exploring one way to potentially boost these approaches and allow next-generation therapies to enter clinical trials,” said Megan Donnell, Executive Director of the Sanfilippo Children’s Foundation.

Dr Alessandro Fraldi leads the Molecular Therapy research group at TIGEM. His interest includes the study of mechanisms underlying the neuropathogenesis of lysosomal storage disorders and developing new therapeutic approaches for the treatment of these disorders.

Project Update

Associate Professor Alessandro Fraldi’s project Searching for “super active” enzymes for Sanfilippo type A has been completed. The project aimed to develop a sulfamidase enzyme more effective at breaking down heparan sulfate, the complex sugar that builds up in Sanfilippo. To be able to test the most promising sulfamidase variants, the team developed a new, high-throughput screening method. The screening method relied on optimised chemical compounds that upon binding to the specific enzyme (sulfamidase in the case of Sanfilippo A) release a fluorescent product, which accumulate within cells, allowing the team to measure the activity of the enzymes in living cells in a very sensitive manner. Unfortunately, the chemistry steps to create the fluorescent compound specific for the sulfamidase proved to be more complex than expected and produced too little material, making it difficult to progress through the project. The team have since worked on new methods to optimise the synthesis of these fluorescent compounds and hope to carry on with the project outside of this grant from the Sanfilippo Children’s Foundation.

Project Summary

• Project title: Generation of “super active” variants of lysosomal enzymes to treat the CNS in Sanfilippo Syndrome
• Chief investigator: Dr. Alessandro Fraldi 
• Amount: $90, 000
• Duration: 1 year
• Location: Telethon Institute of Genetics and Medicine (TIGEM), Naples, Italy
• Status: Completed
• Start date: March 2019

View all funded projects