First patient treated in dose-expansion portion of SpliceBio's phase 1/2 ASTRA clinical trial

SpliceBio has dosed the first patient in the Part B dose-expansion portion of its phase 1/2 ASTRA clinical trial (NCT06942572) evaluating SB-007 for the treatment of Stargardt disease.

SB-007 is an investigational dual adeno-associated virus (AAV) gene therapy designed to restore expression of a functional, full-length ABCA4 protein in the retina, with the potential to treat patients with all ABCA4 mutations. The company stated its proprietary protein splicing intein platform uses 2 AAV serotype 8 (AAV8) vectors to overcome the size limitations of conventional AAVs. Once inside the target cells in the retina, the transgenes are expressed and undergo protein trans-splicing to reconstitute the full-length native ABCA4 protein.¹

Additionally, in preclinical models, SB-007 demonstrated robust pharmacological activity, durable retinal expression, and a favorable safety profile.

Robert MacLaren, MD, PhD, professor of ophthalmology at the University of Oxford and National Health Service gene and cell therapy research lead at Oxford University Hospitals NHS Foundation Trust, commented on SB-007, saying, “The use of 2 viral vectors that recombine once inside retinal cells is a unique approach to restoring the large gene needed in Stargardt disease, and dual vectors might have implications for treating other retinal degeneration. This unique gene therapy modality has the potential to slow or even halt progression of this debilitating disease, which is the most common cause of inherited blindness in children. We are delighted to have treated the first patient here in Oxford, in the critical second phase of the trial.”

ASTRA is a multicenter, global clinical trial designed to evaluate the safety, tolerability, and efficacy of SB-007, enrolling approximately 57 patients aged 12 to 65 with Stargardt disease into Part B. Part A of the study evaluated 3 dose levels of subretinal SB-007 in an open-label, dose-escalation design, while Part B is randomized, controlled, and masked and will evaluate 2 dose levels of subretinal SB-007 compared to an untreated control group, with a follow-up of 96 weeks. The primary endpoint of the trial is safety and tolerability, assessed by the incidence and severity of ocular and non-ocular adverse events.

The U.S. Food and Drug Administration (FDA) recently granted Fast Track designation to SB-007 after it previously received Orphan Drug designation in the US and Europe.

In addition to ASTRA, SpliceBio is also actively enrolling patients in its POLARIS trial, a natural history study monitoring disease progression and endpoints in Stargardt disease patients. According to the company, the aim is to identify the right patients and the right tests to measure for future clinical trials of a novel gene therapy to treat Stargardt disease.

References:

1. SpliceBio Initiates Dose-Expansion Portion of Phase 1/2 ASTRA Clinical Trial for SB-007, a Dual-AAV Gene Therapy for Stargardt Disease. Published January 8, 2026. Accessed January 9, 2026. https://splice.bio/splicebio-initiates-dose-expansion-portion-of-phase-1-2-astra-for-sb-007/

2. SpliceBio Announces U.S. FDA IND Clearance of SB-007 to Commence Phase 1/2 Clinical Study in Patients with Stargardt Disease. Published December 12, 2024. Accessed January 9, 2026. https://splice.bio/splicebio-announces-u-s-fda-ind-clearance-of-sb-007-to-commence-phase-1-2-clinical-study-in-patients-with-stargardt-disease/