The fundraising was spearheaded by Enavate Sciences, with Viking Global Investors and Perceptive Advisors joining as new investors.
The financing round also saw contributions from all current stakeholders, including RA Capital, OrbiMed, TPG’s The Rise Fund, Atlas Venture, the Cystic Fibrosis Foundation, and funds advised by T. Rowe Price Associates as well as Q Healthcare Holdings.
These funds will be utilised to execute the clinical trials of small molecules that can reinstate the function of the cystic fibrosis transmembrane conductance regulator (CFTR) protein.
Cystic fibrosis is a genetic disorder caused by mutations in the CFTR gene, which is crucial for the production of healthy mucus in various organs.
The most prevalent mutation, ΔF508, leads to the malfunction of CFTR by causing the unfolding of the first nucleotide-binding domain (NBD1).
Sionna’s preclinical data, including results from the human bronchial epithelial cell model, have shown that its NBD1 stabilisers can bring ΔF508-CFTR function up to par with the wild-type protein when used with other modulators.
The company’s first clinical-stage NBD1 stabiliser, SION-638, has undergone a Phase I clinical trial, revealing doses that are safe and well-tolerated.
The trial also achieved target exposure at all doses, with increased duration above target at higher doses.
Sionna is planning to bring two more NBD1 stabilisers, SION-451 and SION-719, to clinical trials this year, pending the outcomes of ongoing toxicology studies.
Additionally, Sionna is progressing with the development of compounds targeting complementary mechanisms. This includes SION-109, which interacts with the intracellular loop 4 (ICL4) region of NBD1. A Phase I clinical trial for SION-109 commenced in January 2024.
In conjunction with the funding, Enavate Sciences Commercialization executive vice-president Edd Fleming will join Sionna’s board of directors.
Sionna president and CEO Mike Cloonan said: “We have deep experience in CF and a sharp focus on advancing the development of novel small molecules targeting NBD1 and complementary modulators that enable the potential for full restoration of CFTR function for most people living with CF.
“We are encouraged by the strong interest and validation from the excellent investors in our upsized Series C financing.
“This capital raise provides financial flexibility positioning us to execute our clinical development plan with funding through 2026 and multiple value-creating clinical readouts.”