Immusoft of CA, a clinical-stage biotechnology company pioneering engineered B cell therapies, has announced that the U.S. Food and Drug Administration (FDA) has granted Rare Pediatric Disease (RPD) designation to ISP-002, the company’s investigational therapy for the treatment of mucopolysaccharidosis type II (MPS II), also known as Hunter syndrome.
The FDA grants RPD designation for serious or life-threatening diseases that primarily affect children 18 years old or younger and affect fewer than 200,000 people nationwide.
MPS II is a rare, inherited lysosomal storage disorder caused by a deficiency of the enzyme iduronate-2-sulfatase (IDS), which leads to the accumulation of glycosaminoglycans in tissues and organs throughout the body. The disease primarily affects paediatric patients and is associated with progressive, multisystem involvement, including neurocognitive impairment, cardiopulmonary complications, skeletal abnormalities, and reduced life expectancy. The current standard of care is enzyme replacement therapy, which requires frequent lifelong infusions and may not achieve consistent enzyme exposure across all affected tissues.
ISP-002 is designed to deploy a patient’s own B cells as long-lived protein biofactories capable of continuously producing and secreting therapeutic levels of IDS. By leveraging the natural biology of B cells and their ability to engraft in the bone marrow, ISP-002 is intended to enable sustained systemic enzyme exposure following a single treatment. This approach aims to address limitations associated with existing therapies, including treatment burden, fluctuating enzyme levels, and challenges associated with durable tissue penetration.
Immusoft’s platform modifies autologous B cells ex vivo to produce gene-encoded medicines prior to reinfusion into the patient. Once administered, the engineered B cells are designed to persist for extended periods of time and provide continuous protein expression. The company believes this strategy represents a differentiated therapeutic modality for rare diseases that require long-term or lifelong protein replacement.
“The FDA’s Rare Pediatric Disease designation for ISP-002 recognizes the serious unmet medical need in paediatric patients with MPS II and underscores the potential of Immusoft’s platform as a novel therapeutic approach,” said Sean Ainsworth, chief executive officer of Immusoft.
“This designation supports our continued efforts to advance engineered B cell therapies designed to deliver durable protein expression while maintaining a favourable safety and tolerability profile.”
Preclinical development of Immusoft’s engineered B cell platform was supported in part by funding from the California Institute for Regenerative Medicine (CIRM), which invests in regenerative medicine research to accelerate the development of transformative therapies for patients with unmet medical needs.
ISP-002 builds on Immusoft’s growing pipeline of engineered B cell therapies using its Immune System Programming (ISP) platform. The platform is also being evaluated clinically in ISP-001, the company’s lead investigational therapy for mucopolysaccharidosis type I (MPS I), which has also received FDA Rare Pediatric Disease (RPD) designation. ISP-001 has demonstrated a favourable safety and tolerability profile, along with early evidence of pharmacodynamic activity. Successful re-dosing further underscores its progress, marking an important milestone for the cell and gene therapy field.