What is enzyme replacement therapy?
As of January 2021, all spots have been filled in the Emolden Study clinical trial. The trial is now closed and they are no longer recruiting participants.
Enzyme replacement therapies (or ERT) have shown tremendous promise in treating a number of lysosomal storage disorders like Pompe, Gaucher, Batten and Fabry diseases. Remember, MLD is a leukodystrophy and lysosomal storage disorder. ERT is used to treat genetic disorders just like MLD where there is an insufficient amount of enzyme produced. For the ERT, a functional enzyme is produced in the laboratory by cells that have been genetically modified. The cells are then harvested and the enzyme is purified before being given to the patient.
The clinical trial - The Embolden Study - is an enzyme replacement therapy that requires weekly infusions in the hospital and a surgery of a device to infuse the treatment to the brain and central nervous. The treatment is not expected to be a cure. However, researchers hope it can slow down the disease’s progression and help patients preserve function.
You may have heard about gene therapy in the news, and researchers have long believed gene therapy held great promise for MLD patients. MLD was one of the first diseases to be treated with gene therapy
What is gene therapy?
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.
To learn more about the Orchard Therapeutics’ gene therapy trial, please have your doctor contact Dr. Francesca Fumagalli at Fumagalli.Francesca@hsr.it. Please note the gene therapy clinical trial may require travel to Milan, Italy. You can watch this video featuring the Price family and hear about their remarkable journey.
At the end of 2020, Orchard Therapeutics' MLD gene therapy, Libmeldy, was approved for commercial use in the European Union (EU). They have also begun the process of bringing gene therapy to the United States. Just recently, a pre-approval access site was opened up in Minnesota. Additionally, a late-juvenile arm of the trial in Italy is now actively recruiting (you can find the eligibility criteria here). Learn more about Orchard Therapeutics' updates by visiting their website here.