Orphan Drug Designation for MPS II builds on Immusoft’s clinical progress in MPS I and supports expansion of its engineered B cell platform across multiple indications

SAN FRANCISCO, Dec. 15, 2025 /PRNewswire/ — Immusoft of CA, a clinical-stage biotechnology company pioneering engineered B cell therapies, today announced that the U.S. Food and Drug Administration (FDA) has granted Orphan Drug Designation to ISP-002, the Company’s investigational engineered B cell therapy for the treatment of mucopolysaccharidosis type II (MPS II), also known as Hunter syndrome, a rare and life-threatening lysosomal storage disorder.

MPS II is caused by a deficiency of the enzyme iduronate-2-sulfatase (IDS), which leads to the progressive accumulation of glycosaminoglycans throughout the body. The disease results in multi-system pathology, including skeletal abnormalities, cardiopulmonary complications, and reduced life expectancy. While enzyme replacement therapies are available, they require lifelong, frequent infusions and patients continue to face significant unmet needs related to treatment burden, durability of enzyme exposure, and long-term disease control.

ISP-002 leverages Immusoft’s proprietary engineered B cell platform, which programs a patient’s own B cells to continuously produce therapeutic enzymes inside the body. By enabling sustained enzyme production, the approach has the potential to be a paradigm shift in the treatment of genetic diseases, while addressing key limitations associated with approved therapeutic approaches and investigational gene therapies.

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