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Sionna Therapeutics Announces Presentation of Preclinical Data on NBD1 Stabilizers at 46th European Cystic Fibrosis Conference

– Results from clinically predictive CFHBE model suggest NBD1 stabilizers enable multiple potential paths to full restoration of CFTR function –

Boston, MA, June 8, 2023 — Sionna Therapeutics, a life sciences company dedicated to developing highly effective and differentiated treatments for cystic fibrosis (CF), today announced the presentation of preclinical data demonstrating the activity of the company’s portfolio of compounds targeting the first nucleotide-binding domain (NBD1) of the cystic fibrosis transmembrane conductance regulator (CFTR) protein. The results are being presented at the European Cystic Fibrosis Society (ECFS) 46th European Cystic Fibrosis Conference held June 7-10 in Vienna, Austria.

“Without NBD1 stabilization, the ability to correct the CFTR protein is limited, but this has long been considered an undruggable target in CF,” said Mike Cloonan, President and Chief Executive Officer of Sionna. “Our goal is to deliver new therapies of unprecedented efficacy to patients with a development program that is anchored by NBD1 stabilizers.”

CF is caused by mutations in the CFTR gene, which codes for an epithelial ion channel that is essential for producing healthy, freely flowing mucus in the airways, digestive system, and other organs. The most common mutation in CFTR, ΔF508, causes NBD1 to unfold at body temperature and severely impairs CFTR function. Sionna is developing a portfolio of novel small molecules targeting NBD1 and complementary mechanisms.

In the poster, titled, “Novel CFTR Modulator Combinations Directly Address the ΔF508-CFTR NBD1 Stability Defect and Enable Full CFTR Correction,” Greg Hurlbut, Ph.D., Co-Founder and Senior Vice President, Discovery Research of Sionna, presents data from functional and biochemical assays that demonstrate the activity of Sionna’s NBD1 stabilizers alone and in combination with the company’s intracellular loop 4 (ICL4)- and transmembrane domain 1 (TMD1)-directed correctors, and standard-of-care CFTR modulators.

Sionna’s NBD1 stabilizers demonstrated the ability to restore ΔF508-CFTR maturation, trafficking, and function to wild-type levels when combined with mechanistically complementary agents. Data from the clinically predictive human bronchial epithelial cell (CFHBE) model suggest that NBD1 stabilizers enable multiple potential paths to full restoration of CFTR function for most people living with CF.

“For the past 14 years, our team has focused on the discovery of NBD1 stabilizers and complementary modulators that have the potential to restore wild-type function to ΔF508-CFTR,” said Dr. Hurlbut. “This research has led to a novel strategy for discovering small molecules that directly address the molecular pathology of the most common CF-causing mutation.”

Sionna is currently conducting a Phase 1 clinical trial evaluating its lead NBD1 modulator, SION-638, and has nominated two additional NBD1 modulators, SION-719 and SION-451, entering Investigational New Drug application (IND) enabling studies in the second half of 2023. The company is also advancing the development of compounds targeting complementary mechanisms including SION-109, which targets NBD1’s interface with the ICL4 region, and SION-676, which targets the TMD1 of CFTR.

About Sionna Therapeutics

Sionna Therapeutics is a life sciences company dedicated to developing highly effective and differentiated treatments for cystic fibrosis (CF) by normalizing the function of CFTR, the key protein associated with disease progression in CF. Building on over a decade of extensive research on the genetic mutations associated with CF and founded in 2019, Sionna is advancing a pipeline of small molecules engineered to correct the protein defects caused by ΔF508, the most common mutation that affects the CFTR protein. The company has a first-in-class portfolio of programs directly targeting correction of NBD1, the key and unique mechanism to enable full restoration of ΔF508-CFTR function, and complementary programs targeting ICL4 and TMD1. Sionna’s pipeline has the potential to deliver best-in-class efficacy and reach previously unachievable levels of long-term benefit for people with CF. For information about Sionna visit https://www.sionnatx.com/.

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