There is currently no cure for any MPS disorder. Hematopoietic Stem Cell Transplantation (HSCT) is a high-risk procedure and has proven long-term benefits for MPS I, VI, and VII, but unfortunately it does not help MPS II, MPS III, and MPS VI.
The only FDA approved treatment for MPS II is Enzyme Replacement Therapy (ERT) with Elaprase by Shire pharmaceuticals, which was approved in 2006. ERT is a 3-4 hour intravenous infusion done at a qualified infusion center. It is targeted to replace iduronate-2-sulfatase (I2S), the enzyme that is deficient or absent in people with Hunter syndrome. Although it has proven to slow down the progression of the disease by lessening the GAG build-up in visceral organs (liver, spleen, heart, lungs, etc.), the medicine does not cross the Blood Brain Barrier (BBB) to treat the brain and prevent any neurological decline.
Over the last few years, there have been many scientific advancements in MPS clinical research. Very promising treatments in development include:
AGT-182: by Armagen in collaboration with Shire. A weekly 3-4 hour IV infusion that would cross the BBB.
(This study is only open to children ages 18+ with the less severe version of the disease, which is a very slim population).
Intrathecal IT-idursulfase: by Shire. A monthly infusion of the drug (in addition to the weekly IV infusion) into the Cerebral Spinal Fluid (CSF) to treat the brain. Spinal taps are very risky (especially with an active toddler) and implanted ports to the CSF have been problematic with moving out of place and high risk for infections.
(Noah was not able to make the deadline to be part of this study. It may take years to be approved by FDA).
AAV9 Gene Therapy: by Nationwide Children's Hospital. The most promising, long-lasting treatment for MPS (potentially a cure). A functional copy of the gene that makes the missing enzyme is put into the cells. It is transported by a harmless vector by IV injection that is capable of reaching the brain and is found naturally in the environment. These children would then be capable of producing the enzyme they are deficient with.
This biotechnology had amazing results in the MPS animal study and also has shown promising results in studies for other diseases such as Muscular Dystrophy, Hemophilia, and Cystic Fibrosis.
(The study is ready to go, but they lack the funding. Noah would be a perfect candidate for this clinical trial).
​
RGX-121: by Regenexbio. A similar drug to the one being studied at Nationwide Children's Hospital, but administered directly into CSF. The timeline and details for this study is unknown.
(It has not been clear if they will open their study to pediatrics).
​
SB-913: by Sangamo. A gene editing approach inserting a functional copy of the gene into a small percentage of liver cells. The liver can then produce the missing enzyme potentially at high levels inside the body, but it does not seem to treat the brain.
(This study is only open to children ages 18+ with the less severe version of the disease, which is a very slim population).
