Spanish biotechnology firm SpliceBio has secured $135 million in Series B funding to advance its innovative gene therapy program targeting Stargardt disease, marking a significant milestone in the company’s development of next-generation genetic treatments.
The funding round, announced Wednesday, 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 technology addresses a fundamental limitation in current gene therapy approaches. Traditional gene therapies rely on
adeno-associated viruses (AAVs) to deliver genetic material into cells, but these viral vectors have limited cargo capacity. This size constraint has prevented effective treatment of conditions requiring larger genes, forcing companies to develop compromised solutions.
The company’s novel approach utilizes a dual AAV system, where two separate viral vectors carry different portions of a large gene. Once inside cells, specialized splicing molecules help reconstruct the complete protein from these segments. This technique is particularly relevant for treating Stargardt disease, which is caused by mutations in the ABCA4 gene – too large to fit within a single AAV vector.
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 also developing a similar program in early clinical stages.
The technology underlying SpliceBio’s platform emerged from research at Princeton University, where CEO and co-founder Miquel Vila-Perelló conducted studies in protein design and engineering. The company, which began operations in 2014 under the name ProteoDesign, is expanding its pipeline to include programs in ophthalmology, neurology, and other undisclosed therapeutic areas.
Vila-Perelló emphasized the significance of securing backing from major 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. This latest funding follows the company’s €50 million Series A round completed in 2022.
The investment represents part of a broader trend in gene and cell therapy financing during 2025. According to BioPharma Dive’s tracking of approximately two dozen investment firms, genetic medicine startups have accumulated over $1.1 billion in venture funding this year. Notably, half of these investments have been “megarounds” exceeding $100 million, continuing an established pattern in the sector.
The development of dual AAV technology could potentially overcome one of gene therapy’s most significant technical barriers. Current limitations are particularly evident in conditions like Duchenne muscular dystrophy, where companies such as Sarepta Therapeutics have had to develop shortened versions of the dystrophin gene due to AAV packaging constraints. These abbreviated versions may not provide optimal therapeutic benefit compared to full-length proteins.
SpliceBio’s technology might offer a solution to this challenge by enabling the delivery of complete genes through its innovative splitting and reassembly approach. This advancement could expand the range of genetic conditions amenable to gene therapy treatment, particularly those involving larger genes that have previously been difficult to address with conventional AAV vectors.
The substantial funding round demonstrates continued investor confidence in novel gene therapy approaches, despite broader market challenges in the biotech sector. It also highlights the industry’s ongoing efforts to overcome technical limitations that have
historically restricted the scope of genetic medicine.
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