What is gene therapy?

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Gene therapy has been around for decades, but it was in 2009 when a researcher named Alessandra Biffi attempted to treat a child with MLD using gene therapy at the Telethon Institute in Milan, Italy  There are many forms of gene therapy, but Dr. Biffi used a treatment called lentiviral hematopoietic  stem cell gene therapy. Dr. Biffi and her colleagues believed that they could replace the broken ARSA gene mutation that causes MLD with a working copy of the gene to start producing the arylsulfatase A enzyme. Dr. Biffi hoped the treatment would  slow down the disease’s progression. Much to Dr. Biffi and her colleague’s amazement, this pioneering gene therapy exceeded all expectations and the first children had MRIs that appeared normal two years after treatment.  

 

What is even more remarkable is how gene therapy works. To replace a broken gene, researchers need a vehicle to transport the corrected gene to our cells. That vehicle is the HIV virus, stripped of its harmful properties. You see, viruses are really good at getting inside and telling them what to do. HIV is a very efficient virus. And researchers hoped they would be able to  “infect” a patient’s cells with a repaired copy of the ARSA gene they needed to be healthy.   

 

The treatment shows great potential but, sadly, cannot be used on all patients. Moreover, since most MLD patients are diagnosed after they have symptoms, gene therapy is not as effective. One of the most important efforts of Cure MLD will be newborn screening. Identifying children at birth who will develop MLD will be crucial to defeating MLD.

 

You see, gene therapy works by slamming the brakes on a disease to halt MLD’s progression. It cannot repair the damage to the brain or central nervous system.

 

While the results of the research have been impressive, some patients treated with MLD can walk, others use walkers or wheelchairs. Moreover, it is not clear how long the therapy will stop the disease’s progression. But, the research on gene therapy for MLD has offered new hope for our community.  However, as gene therapy becomes more efficient, safe, and fast-acting, we expect to see new treatments available to a wider range of patients, possibly even symptomatic ones.

 

Watch this video featuring Dr. Biffi discussing her work to develop a gene therapy.  

https://www.youtube.com/watch?v=HWQGfBB1nQM&t=15s

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