Argonaute protein and microRNA
Argonaute protein. Molecular model of human argonaute-2 protein complexed with microRNA (micro ribonucleic acid). This protein is part of the RNA-induced silencing complex (RISC). RISC plays a role in gene regulation and defence against viral infection.

SpliceBio has completed an oversubscribed, more than $56 million (€50 million), series A financing to support development of its novel gene therapy delivery technology and its first treatment. The proceeds from the financing, the largest Series A round for a Spanish biotech company, will enable the company to build a pipeline of Protein Splicing gene therapy programs, while advancing its lead program in Stargardt disease to the clinic.

The financing was co-led by UCB Ventures and existing shareholder Ysios Capital and joined by new investors New Enterprise Associates (NEA), Gilde Healthcare, Novartis Venture Fund, and existing shareholder Asabys Partners. The Company was seeded in 2020 by Ysios Capital and Asabys Partners.

Miquel Vila-Perelló, co-founder and chief executive officer of SpliceBio, said, “We are very pleased to attract this outstanding syndicate of institutional and corporate investors which validates our approach to developing next generation gene therapies. I am excited to lead an exceptional team as we continue to build our platform and advance our pipeline of gene therapy programs into the clinic.”

Adeno-associated viruses (AAV) are currently the vector of choice, however, their small packaging capacity is a major challenge for the development of new gene therapies.

SpliceBio’s Protein Splicing platform aims to enable delivery of large genes with AAV vectors. The platform is based on technology developed in the Muir Lab at Princeton University after more than 20 years of pioneering intein and protein engineering research.

Inteins are a family of proteins that carry out protein splicing, a multi-step biochemical reaction comprised of both the cleavage and formation of peptide bonds. In SpliceBio’s novel approach, engineered inteins catalyze highly efficient protein trans-splicing to reconstitute the desired full-length therapeutic protein in vivo. In short, the genes are delivered in separate packages, put back together, and then the inteins are shorn off.

Since the 1990s, SpliceBio co-founders have been pioneering research with inteins. However, inteins found in nature presented several limitations for use as therapeutics. SpliceBio co-founders at Princeton University developed a new generation of these molecules that overcome the limitations of natural inteins and are designed for therapeutic use—engineered split inteins.

Stargardt disease is the most common form of juvenile macular dystrophy and affects more than 80,000 people in U.S. and E.U. The disease is caused by a loss of function mutation in the ABCA4 gene, which at 6.8 kb is too large for single AAV vectors.

The company will focus its efforts on ophthalmology as well as other disease areas of significant unmet patient need. The platform has been validated in several other organs beyond the retina.

Following the closing of the financing, the Board of SpliceBio chaired by Jean Philippe Combal will include: Erica Whittaker, UCB Ventures; Joël Jean-Mairet, Ysios Capital; Ed Mathers, NEA; Arthur Franken, Gilde Healthcare; Beat Steffen, Novartis Venture Fund; and Vila- Perelló, CEO.

Whittaker, Vice President and Head of UCB Ventures, said, “We are delighted to support SpliceBio in the development of its innovative platform to create treatments for patients suffering from genetic diseases not currently addressable by existing gene therapy approaches.”

Jean-Mairet, Managing Partner at Ysios Capital, added, “We are proud to have been involved with the Company since its early days and are very impressed with the progress achieved to date. SpliceBio’s platform represents an unprecedented opportunity to expand the universe of diseases that can be addressed with gene therapy. This financing is also a testament to the growing potential of the biotech hub in Barcelona.”

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