Spanish biotechnology firm SpliceBio has secured $135 million in Series B funding to advance its innovative gene therapy platform targeting Stargardt disease, a genetic eye condition that leads to progressive vision loss.
The funding round was jointly led by EQT Life Sciences and Sanofi Ventures, with participation from several other prominent investors including Roche Venture Fund, New Enterprise Associates, and Novartis Venture Fund.
SpliceBio’s approach addresses a fundamental limitation in current gene therapy treatments. Traditional gene therapies utilize
adeno-associated viruses (AAVs) as delivery vehicles, but these viral vectors have limited cargo capacity, making it difficult to transport larger therapeutic genes. The company’s solution involves using two separate AAVs to deliver different segments of a large gene, which are then reassembled inside cells using specialized splicing molecules.
This technology is particularly relevant for treating Stargardt disease, which is caused by mutations in the ABCA4 gene. The size of this gene exceeds the carrying capacity of a single AAV vector. Through its dual-vector approach, SpliceBio aims to enable the production of fully functional proteins from large genes that were previously unsuitable for AAV-based gene therapy.
The company’s lead candidate, SB-007, has entered Phase 1/2 clinical trials. SpliceBio isn’t alone in pursuing this therapeutic strategy for Stargardt disease, as European competitor AAVantgarde is developing a similar program in early-stage testing.
The technology underlying SpliceBio’s platform emerged from research at Princeton University, where company co-founder and CEO Miquel Vila-Perelló conducted studies in protein design and engineering. Originally established in 2014 under the name ProteoDesign, the company has expanded its focus beyond ophthalmology to include neurological conditions and other undisclosed therapeutic areas.
Vila-Perelló emphasized the significance of attracting high-caliber investors, stating that their support validates both the company’s programs and its unique protein splicing platform’s potential to develop treatments for previously untreatable conditions. The latest funding follows the company’s €50 million Series A round completed in 2022.
The investment in SpliceBio represents part of a broader trend in gene and cell therapy funding. According to BioPharma Dive’s tracking of approximately two dozen investment firms, the sector has attracted over $1.1 billion in venture capital during 2025. Notably, half of these investments have been “megarounds” exceeding $100 million, continuing a pattern seen in recent years.
This substantial funding reflects ongoing investor confidence in novel approaches to gene therapy, particularly those addressing current technological limitations. The ability to deliver larger genes could potentially expand the range of treatable genetic conditions, opening new possibilities in genetic medicine.
SpliceBio’s dual-vector technology offers an alternative to other approaches being used in the field, such as the development of shortened versions of therapeutic proteins. This method has been employed by companies like Sarepta Therapeutics in treating Duchenne muscular dystrophy, where the full-length dystrophin gene exceeds AAV capacity. However, such truncated proteins may not function as effectively as their complete counterparts.
The company plans to use the new funding to advance its clinical program in Stargardt disease while continuing to develop its platform technology for application in other therapeutic areas. This investment positions SpliceBio to further validate its approach to overcoming one of gene therapy’s most significant technical challenges.
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