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Toward a life-changing new therapy

Building on our breakthroughs to alter the course of Parkinson’s disease

No disease-modifying therapies currently exist for Parkinson’s disease. Leveraging our more stable GCase85 enzyme, our gene therapy candidate, SPR301, could change that.

A genetic indication of a more debilitating condition 

Parkinson’s disease impacts the nervous system, resulting in tremors and difficulty walking or moving, as well as anxiety, depression, and cognitive impairments. Symptoms often emerge slowly and get progressively worse over the years. There is no cure, and symptomatic treatments become less effective over time.

Between 5% and 15% of people with Parkinson’s disease have mutations in the GBA1 gene. These mutations are the most common genetic risk factor for Parkinson’s disease and are associated with earlier disease onset, more severe symptoms, and an increased risk for dementia.

A new indication for a promising enzyme

The GBA1 gene is responsible for the production of the GCase enzyme, which is needed for the effective breakdown of certain substances within cells. Mutations in the GBA1 gene can lead to a critical deficiency of GCase. This in turn leads to abnormal proteins accumulating in the brain and the loss of neurons that help control body movements.

Our more stable enzyme, GCase85, could help counteract this deficiency. The enzyme was originally designed as part of our work on FLT201, our clinical-stage gene therapy program in Gaucher disease. Preclinical and early clinical data from that program show that our GCase85 has robust expression in the body that can reduce the buildup of harmful substances—revealing its potential to be part of a transformative new therapy for GBA1 Parkinson’s.

Toward a disease-modifying gene therapy

Our product candidate, SPR301, uses an AAV9 capsid, known for its broad distribution across the brain, to deliver GCase85 to areas of the brain impacted by Parkinson’s disease. In a series of preclinical studies, SPR301 demonstrated substantially higher GCase activity and greater reduction of toxic substrates than delivery of wildtype GCase, as well as a greater reduction in α-synuclein, a hallmark of Parkinson’s disease.

Based on the data from preclinical studies, we believe SPR301 has the potential to change the course of GBA1 Parkinson’s disease at doses with a favorable safety profile. We are conducting additional preclinical studies and plan to initiate a Phase 1/2 clinical trial in 2026.

Published results and data