The US Food and Drug Administration (FDA) has granted an orphan drug designation to ArmaGen Inc.’s GT-184 for the treatment of mucopolysaccharidosis type IIIA, also known as Sanfilippo Syndrome A or MPS IIIA.
"We are very pleased to receive FDA orphan drug designation for AGT-184, as this designation is an important regulatory milestone for the Company as we work to develop a potential treatment option for patients suffering from this rare and life-threatening disease," said Mathias Schmidt, PhD, chief executive officer of ArmaGen, in a recent statement
. "This moment represents a transformational period in the Company's evolution as we prepare to leverage our clinically validated BBB platform to advance additional pipeline assets."
AGT-184 is an IgG-SGSH fusion protein, where the IgG domain is a human anti-insulin receptor monoclonal antibody. By binding to endogenous insulin receptors present on the blood-brain barrier (BBB), the insulin receptor antibody domain triggers transport of the AGT-184 fusion protein across the BBB.
The applicability of ArmaGen’s “Trojan Horse” approach to MPS IIIA proved effective in an MPSIIIA mouse model in which a surrogate version of AGT-184 (AGT-m184) showed activity in both central nervous system (CNS) and somatic organs. The mice were treated 3 times per week for the duration of 6 weeks with AGT-m184.
At the end of the 6-week study, a 70% reduction in brain heparan sulfate levels was observed in mice treated with the investigative therapy, providing direct evidence that the fusion protein successfully crossed the BBB to deliver the SGSH enzyme payload into the brain. Additionally, an 85% reduction in liver heparan sulfate levels was observed in comparison with the control, providing evidence of somatic or peripheral activity of the IgG-SGSH fusion protein. These findings
MPS IIIA is a severe, progressive disorder that affects the central nervous system. Individuals with MPS IIA are unable to break down heparan sulfate. The condition arises from a deficiency in the gene encoding for the enzyme N-sulfoglucosamine sulfohydrolase, which leads to an accumulation of complex sugar polymers within the brain. This leads to progressive intellectual disability and developmental regression.