With Positive Results in Fabry Disease, Sangamo Heading for Phase III

Fabry Disease

Sangamo Therapeutics announced positive preliminary findings from its ongoing Phase I/II STAAR clinical trial on the effectiveness of gene therapy candidate isaralgagene civaparvovec (ST-920) in treating Fabry disease.

ST-920 is administered as a one-time infusion without the need for preconditioning. It is currently being evaluated in participants undergoing enzyme replacement therapy (ERT) for Fabry disease who are ERT pseudo-naive (or off ERT for at least six months) and are ERT-naive. The patients' ages range from 22 to 48 years. 

The initial results are based on data available as of its September 17 cutoff date, including four patients on the first two dose cohorts of ST-920 (0.5e13 vg/kg and 1e13 vg/kg). The study consists of six participants in total, with the fifth patient, who is part of the third dose cohort (3e13 vg/kg), dosed after the cutoff, and the sixth still undergoing the screening process also for the third cohort.

The results for the four patients show an above normal alpha-galactosidase. Activity was maintained up to one year for the first patient treated and 14 weeks for the latest treated participant. An activity of 2- to 15-fold above mean normal was also observed during the period. The patients also did not report any treatment-linked adverse events above Grade 1 (mild), nor any liver enzyme elevations. 

Fabry disease is a rare lysosomal storage disorder caused by mutations in the galactosidase alpha gene, leading to low alpha-galactosidase A activity. The latter is essential to metabolize globotriaosylceramide, which can cause severe damage to the body's vital organs if it accumulates. It can harm the nerves, eyes, heart, kidney, skin and gut. 

Those diagnosed with the disease typically experience low heat tolerance, inability to sweat, vision problems, skin blemishes, neuropathic pain, tingling in the extremities, mood disorders, gastrointestinal problems and heart failure. Current treatments involve a series of infusions that only manage some symptoms but do not really treat the disease.

"We are encouraged by these early yet promising results, particularly that the first three treated patients dosed all reported improvements in their ability to sweat, which is noteworthy as this limits a person’s capability to tolerate strenuous tasks and exercise," said Dr. Rob Schott, M.D., M.P.H., F.A.C.C., the head of development at Sangamo. "As we continue with this study, we hope to further understand the potential treatment effect over the longer-term and in more patients, while we initiate plans for a Phase III trial."

The U.S. Food and Drug Administration has granted ST-920 an Orphan Drug designation. The European Medicines Agency (EMA) also gave it an Orphan Medicinal Product designation.

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