Sionna Therapeutics, Inc.

The round secures funding for the company through 2026. Image credit: Shutterstock/OlekStock. Sionna Therapeutics has continued raising capital, closing a $182m Series C financing round to help advance additional cystic fibrosis candidates into clinical trials. The round, which was upsized and oversubscribed according to the US company, will see Sionna forge ahead with the clinical development of assets designed to stabilise the first nucleotide-binding domain (NBD1) in patients with cystic fibrosis. The round, which follows a $111m Series B round in 2022, secures the company’s cash runway through 2026. Sionna’s lead asset is SION-638 – an NBD1 stabiliser currently in Phase I trials. The first subject was dosed in January 2024, with the company stating that target exposure was achieved at all doses. Sionna said it will now advance two NBD1 stabilisers from its second series – SION-451 and SION-719. The two candidates are slated to join SION-638 in clinical trials in 2024, according to a 6 March press release. See Also: Amylyx considers scrapping ALS drug following Phase III flop Mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene lead to cystic fibrosis. The gene codes for a transmembrane channel that produces mucus, which is usually thin and slippery in healthy individuals but thick and sticky in cystic fibrosis patients. One of the most common CFTR mutations—F508del—leads to NBD1 unfolding, which negatively affects CFTR function. Sionna says that its NBD1 stabilisers are designed to restore the function of the CFTR gene. Alongside its trio of NBD1 stabilisers, Sionna is investigating complementary mechanisms in the disease. The company’s CFTR intracellular loop 4 (ICL4) inhibitor SION-109 entered a Phase I trial in January 2024. The cystic fibrosis market is largely dominated by the Boston, Massachusetts-based Vertex Pharmaceuticals . Sionna stands to benefit from that expertise, with Vertex’s former vice president of clinical development for cystic fibrosis Charlotte McKee joining the company as chief medical officer, in 2022. Vertex’s Trifakta or Kaftrio (elexacaftor / tezacaftor / ivacaftor) drove much of the company’s revenue growth for 2023. The combo therapy, which is indicated for cystic fibrosis patients who have at least one F508del mutation, was originally US Food and Drug Administration-approved in 2019 and has since been granted label expansions . Trifakta saw sales of $8.9bn in 2023, up 16% from 2022. Vertex also has Symdeko (tezacaftor / ivacaftor), Orkambi (lumacaftor/ivacaftor), and Kalydeco (ivacaftor) as other FDA-approved therapies in the cystic fibrosis space. The company is also planning fast-track regulatory submissions for another triple therapy, involving vanzacaftor, by mid-2024 following positive Phase III results . Sionna’s CEO Mike Cloonan said: “This capital raise provides financial flexibility positioning us to execute our clinical development plan with funding through 2026 and multiple value-creating clinical readouts.”

Sionna's new financing adds momentum to its chase of Vertex in the cystic fibrosis market. Sionna Therapeutics has closed a $182 million series C, enough to last through 2026 and more than double the number of cystic fibrosis treatments in clinical development.   The midstage raise announced Wednesday is just the latest evidence that biotechs are biding their time before testing Wall Street. Sionna CEO Mike Cloonan told Fierce Biotech this will be the company’s last private financing but declined to put a timescale on when the company could go public. “We want as much clinical data as possible and we want that to put ourselves in the best position as to when we would IPO,” Cloonan said. Sionna is the latest example of the benefits of biotechs maintaining a tight therapeutic focus, be it on a single asset or disease area. The sole priority of the company—for now, at least—is developing cystic fibrosis treatments, with a lead candidate set to report interim phase 1 data in the next few months.  Sionna’s candidate is one of three NBD1 inhibitors in development with the other two set to enter the clinic before the end of the year. The plan, according to Cloonan, is for Sionna to select the best performer to take into a phase 2 trial once data on all three have been accrued.   While this NBD1 work may be Sionna’s main course, the side dishes are just as important. The first, SION‑109, is an ICL4 inhibitor that began a phase 1 trial earlier this year. The second potential add-on med, SION-676, is targeting TMD1 and is slated for the clinic in 2025. Similar to the NBD1 programs, those two will be assessed based on phase 1 data with the more compelling candidate taken into a proof-of-concept trial as a combo with the lead NBD1 asset. The new financing allows Sionna to afford all of these clinical assessments before a phase 2 trial.  “Right now, it's looking like [SION-109] could be the best combination asset just based on what we know today,” Cloonan said.  Sionna unveiled in April 2022 after closing a $111 million series B, hiring Charlotte McKee, M.D., Vertex’s former vice president of clinical development for cystic fibrosis work, as its chief medical officer. It’s a market largely dominated by Vertex, but there’s room for new entrants, with one recent estimate projecting that the global cystic fibrosis market could top $37 billion by 2030. The clear market potential plus Sionna’s multiple candidates has made it a prized option among investors, Cloonan believes.  “If we were a single shot on goal in this big market, that's more risk for an investor,” he said. “But because we have this portfolio of options … it really was attractive to the investors in terms of how they think about the risk of return.”

- Company positioned to have four compounds in clinical trials in 2024 including three NBD1 stabilizers and one ICL4 modulator - - Edd Fleming, M.D., of Enavate Sciences joins company's Board of Directors - BOSTON, March 6, 2024 /PRNewswire/ -- Sionna Therapeutics, a clinical-stage life sciences company dedicated to developing highly effective and differentiated treatments for cystic fibrosis (CF), today announced the closing of a $182 million Series C financing to support the clinical development of first-in-class small molecules designed to fully restore the function of the cystic fibrosis transmembrane conductance regulator (CFTR) protein by stabilizing the first nucleotide-binding domain (NBD1). The Series C round, which was upsized and oversubscribed, was led by Enavate Sciences with additional new investors Viking Global Investors and Perceptive Advisors, as well as participation by all existing investors including RA Capital, OrbiMed, TPG's The Rise Fund, Atlas Venture, the Cystic Fibrosis Foundation, funds and accounts advised by T. Rowe Price Associates, Inc., and Q Healthcare Holdings, LLC., a wholly owned subsidiary of QIA. Sionna also announced today that Edd Fleming, M.D., Executive Vice President of Commercialization at Enavate Sciences, is joining its Board of Directors. "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," said Mike Cloonan, President and Chief Executive Officer of Sionna. "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. We are also pleased to welcome Dr. Fleming to our Board and look forward to insights from his more than 30 years of experience in the health care industry." 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 has presented preclinical data, including data from the clinically predictive human bronchial epithelial cell (CFHBE) model, that demonstrate its NBD1 stabilizers can restore ΔF508-CFTR maturation, trafficking, and function to wild-type levels when combined with complementary modulators. A Phase 1 clinical trial of its first clinical-stage NBD1 stabilizer, SION-638, has identified doses that are generally safe and well tolerated, and target exposure (based on the CFHBE assay) was achieved at all doses, with more time above target with increasing dose. Sionna has nominated two additional NBD1 stabilizers from its second series, SION-451 and SION-719, and plans to advance both compounds to clinical trials in 2024 pending results from ongoing Good Laboratory Practice (GLP) toxicology studies. In addition, the company is continuing to advance the development of compounds targeting complementary mechanisms including SION-109, which targets NBD1's interface with the CFTR intracellular loop 4 (ICL4) region; a Phase 1 clinical trial with SION-109 began in January 2024. About Sionna Therapeutics Sionna Therapeutics is a clinical-stage 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 . Media Contact Adam Daley Berry & Company Public Relations 212.253.8881 [email protected] Investor Contact [email protected] SOURCE Sionna Therapeutics