Orchard Therapeutics Reports Early Positive Neurocognitive Outcomes for OTL-201 in MPS-IIIA

Orchard Therapeutics has reported early clinical findings, including the first neurocognitive data, from its ongoing proof-of-concept study of OTL-201, an investigational hematopoietic stem cell (HSC) gene therapy for mucopolysaccharidosis type IIIA (MPS-IIIA).

The study involved five patients aged 6 to 24 months at the time of OTL-201 administration. All participants achieved sustained engraftment of gene-corrected cells and supraphysiological levels of the SGSH enzyme in leukocytes, which were sustained through the last follow-up visit. SGSH levels in cerebrospinal fluid were within or above the normal range by six months post-treatment.

Early neurocognitive outcomes indicate that four out of the five patients have demonstrated a gain of cognitive skills in line with the development of healthy children. One patient showed a marked improvement compared to the natural history of the disease at 18 months of follow-up. Three additional patients are currently within the normal developmental quotient (DQ) range, although longer follow-up is needed.

Treatment with OTL-201 was generally well-tolerated. Six serious adverse events (SAEs) have been reported to date, with some attributed to conditioning or leukapheresis. No signs of insertional oncogenesis or clonal dominance have been observed to date.