Sionna Therapeutics to Present Data at the 2026 North American Cystic Fibrosis Conference

Post hoc clinical findings and new laboratory data support a planned combination trial expected to begin in the first quarter of 2027.

Rhea-AI Summary

Sionna Therapeutics (SION) presented clinical analyses and new preclinical cystic fibrosis data at the 2026 North American Cystic Fibrosis Conference.

PreciSION CF, evaluating SION-719 added to Trikafta, did not achieve its key activity endpoint. Post hoc analyses excluding three participants with drug-exposure patterns consistent with dosing non-adherence showed a mean placebo-adjusted sweat chloride reduction of 8.6 mmol/L. Lower exposure to all three Trikafta components and a potential interaction with ivacaftor complicated interpretation. In laboratory studies, NBD1-stabilizer combinations improved CFTR protein trafficking and function up to wild-type levels in cells from donors with one or two F508del copies. Sionna expects the SION-451 + SION-2222 AscenSION CF Phase 2a trial to begin in the first quarter of 2027.

4 points · 0 major

MixediHow this balance works

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Rhea-AI gives every point it takes from this document a weight. Minor counts 1, Moderate 3 and Major 9, so one Major point outweighs several Minor ones. The bar adds up the weights on each side, and when neither side holds more than 65% of the total the balance reads Mixed.

It reads the document as published, with the same rules for every company, and it does not look at what the market expected or at how the stock traded, so a point can be objectively good on a day the stock falls.

Rhea-AI Sentiment measures something else, the tone of the wording.

How the balance worksHow Sentiment works

1 major · 3 points

Hollow bars mark forward-looking points. How the balance works

Positive

• Moderate pointPhase 1 results showed favorable safety, tolerability and pharmacokinetics, supporting advancement of SION-451 + SION-2222.
• Moderate point. Forward-looking: it has not happened yet and may not happen.AscenSION CF Phase 2a testing SION-451 + SION-2222 is expected to begin in the first quarter of 2027.
• Minor pointPost hoc analyses excluding three participants showed a mean placebo-adjusted sweat chloride reduction of 8.6 mmol/L.
• Minor pointPreclinical NBD1-stabilizer combinations improved CFTR trafficking and function up to wild-type levels across both donor groups.

Negative

• Major pointPreciSION CF did not achieve its key activity endpoint with SION-719 added to Trikafta.
• Moderate pointAll three Trikafta components had lower exposures during SION-719 treatment periods, signaling a complex four-drug interaction.
• Minor pointA potential SION-719–ivacaftor interaction may have blunted the additional benefit of NBD1 stabilization.

Key Figures

Placebo-adjusted sweat chloride reduction: 8.6 mmol/L Participants excluded from post hoc analyses: 3 participants Trial duration: 28 days +1 more

Placebo-adjusted sweat chloride reduction

8.6 mmol/L

Post hoc analyses excluding three participants with dosing non-adherence patterns

Participants excluded from post hoc analyses

3 participants

Excluded for PK patterns consistent with dosing non-adherence

Trial duration

28 days

AscenSION CF Phase 2a proof-of-concept trial

Expected trial start

First quarter of 2027

AscenSION CF Phase 2a trial

Historical Context

2 past events · Latest: Sep 14

2 events

1. Sep 14

   Program update

   24h Move

   -16.8%

   Outlined the 28-day AscenSION CF trial of the same SION-451 plus SION-2222 combination.

2. Aug 10

   Clinical results

   24h Move

   -91.2%

   Reported PreciSION CF missed its key activity endpoint and SION-719 would not advance as an add-on.

24h Move is the share-price change in the day after each event; other market factors may also have contributed.

Key Terms

cftr, f508del, post hoc, proof-of-concept

4 terms

cftr medical

"other CFTR modulators across F508del genotype groups"

CFTR is a gene that makes a protein acting like a tiny gate in cell membranes to control the flow of salt and water; when the gate works properly it helps keep mucus thin and organs functioning. Investors care because mutations in CFTR drive serious diseases and create demand for diagnostics, drugs and long-term treatment revenue; progress or setbacks in therapies, approvals or patents directly affect company value.

f508del medical

"across F508del genotype groups demonstrated the potential"

f508del (also written ΔF508 or F508del) is a specific genetic mutation in the CFTR gene that removes the amino acid phenylalanine at protein position 508. The deletion causes the CFTR protein to misfold and be retained and degraded inside cells rather than reaching the cell surface as a functional chloride channel, producing the characteristic ion-transport defect seen in cystic fibrosis and making it a primary target for therapies called correctors and potentiators.

post hoc technical

"previously disclosed post hoc analyses of the PreciSION CF Phase 2a trial"

Post hoc means “after the fact” and describes conclusions or analyses made only after seeing results rather than set up beforehand. Investors should treat post hoc findings like noticing a pattern after the game has been played — they can suggest possibilities but are prone to coincidence or bias and often require rigorous, preplanned testing to be trusted. Overreliance on post hoc reasoning can lead to bad bets or misreading a company’s prospects.

proof-of-concept medical

"Phase 2a proof-of-concept trial assessing sweat chloride"

A proof-of-concept is a demonstration that shows a new idea or method can work as intended, serving as a small-scale test before full development. For investors, it signals that a concept has been successfully tested in principle, reducing uncertainty about whether it can be practically implemented. This helps determine if further investment or effort is justified to develop the idea further.

AI-generated analysis. How Rhea-AI works. Not financial advice.

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Previously disclosed post hoc PreciSION CF analyses of SION-719 support advancement of SION-451 + SION-2222 into the AscenSION CF Phase 2a proof-of-concept trial

New preclinical data evaluating NBD1 stabilizers in combination with other CFTR modulators across F508del genotype groups demonstrated the potential of NBD1 stabilizer-based combinations to benefit a broad population of people with CF

WALTHAM, Mass., Oct. 08, 2026 (GLOBE NEWSWIRE) -- Sionna Therapeutics, Inc. (Nasdaq: SION), a clinical-stage biopharmaceutical company on a mission to develop novel medicines for cystic fibrosis (CF), today announced data being presented at the 2026 North American Cystic Fibrosis Conference (NACFC) being held in Atlanta, Georgia on October 7-10, 2026.

Details of the presentation and posters are as follows:

Presentation Title: NBD1 is a novel target in Cystic Fibrosis, Clinical Learnings and Research Data
Presenters: Gregory S. Sawicki, M.D., M.P.H., Director of the Cystic Fibrosis Center at Boston Children's Hospital and Associate Professor of Pediatrics at Harvard Medical School and Steve Altmann, M.S., Director of Research, Sionna Therapeutics
Session Title: S09 - Approaches to Increasing CFTR Expression & Function
Date and Time: Thursday, October 8th, 2026, 4:30 p.m. – 6:30 p.m. ET

Presentation Summary:
The oral presentation by Dr. Sawicki is a summary of the previously disclosed post hoc analyses of the PreciSION CF Phase 2a trial evaluating NBD1 stabilizer SION-719 when added to Trikafta. Although the trial did not achieve its key activity endpoint, post hoc analyses excluding three participants with PK patterns consistent with dosing non-adherence showed a mean placebo-adjusted sweat chloride reduction of 8.6 mmol/L. The analyses also identified lower exposures of all three Trikafta components during SION-719 treatment periods, signaling a complex four-drug interaction. In addition, there was a potential interaction between the NBD1 stabilizer SION-719, and the potentiator, ivacaftor, that may have blunted the additional benefit of NBD1 stabilization. The Company believes these findings alongside the nonclinical data presented by Steve Altmann are consistent with NBD1 biological activity. Taken together with favorable Phase 1 safety, tolerability and PK results, these data support advancing SION-451 + SION-2222 into AscenSION CF, an open-label, 28-day Phase 2a proof-of-concept trial assessing sweat chloride, safety and PK in adults with CF homozygous for F508del. The trial is expected to begin in the first quarter of 2027.

Poster Title: Assessing the effect of NBD1 stabilizers SION-451 and SION-719 in combination with other CFTR modulators on primary human bronchial epithelial cells from F508del/F508del and F508del/null donors
Authors: S. Altmann, S. Bercury, J. Foley, Z. Gao, A. Hunnicutt, Liao, A. Madanjian, M. Munson, G. Topalov, G. Hurlbut.
Poster Number: 295

Poster Summary: Sionna conducted preclinical experiments to assess the effects of Sionna’s clinical-stage NBD1 stabilizers, SION-451 and SION-719, in combination with complementary modulators, including SION-2222 (TMD1-directed modulator) and SION-109 (ICL4-directed modulator), across primary CF human bronchial epithelial (CFHBE) cells from donors with either one or two copies of F508del. Across both donor groups, NBD1-stabilizer combinations demonstrated improved CFTR trafficking and function up to wild-type levels, supporting their potential to benefit a broad population of people with CF.

The presentation and poster are available under the “Scientific Presentations” section within the Science page of Sionna’s website at https://www.sionnatx.com/our-science/.  

About Sionna Therapeutics
Sionna Therapeutics is a clinical-stage biopharmaceutical company on a mission to revolutionize the current treatment paradigm for cystic fibrosis (CF) by developing novel medicines that improve the function of the cystic fibrosis transmembrane conductance regulator (CFTR) protein. Sionna’s goal is to deliver differentiated medicines for people living with CF that can restore their CFTR function to as close to normal as possible by directly stabilizing CFTR’s nucleotide binding domain 1 (NBD1), which Sionna believes is central to potentially unlocking meaningful improvements in clinical outcomes and quality of life for people with CF. For more information about Sionna, visit www.sionnatx.com.

Cautionary Note Regarding Forward-Looking Statements
This press release contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995, as amended, including, without limitation, implied and express statements about Sionna’s beliefs and expectations regarding: its goal of transforming the treatment paradigm for CF; its interpretation of the results of the PreciSION CF trial and the impact of potential confounding factors on the interpretation of those results; the potential for NBD1 stabilization to improve CFTR function and produce clinical benefit, including beliefs about biological activity of SION-719 in PreciSION CF and the translatability of preclinical and in vitro assay data to clinical outcomes; the objectives, design, timing, initiation and conduct of a planned Phase 2a proof-of-concept trial of SION-451 + SION-2222; the therapeutic potential, clinical benefits and safety of SION-451 + SION-2222; and other statements that are not historical facts.

In some cases, forward-looking statements can be identified by terms such as “may,” “will,” “should,” “would,” “expect,” “plan,” “anticipate,” “could,” “intend,” “target,” “project,” “believe,” “estimate,” “predict,” “potential” or “continue,” or the negative of these terms or other similar expressions. Any forward-looking statements are based on management’s current expectations and beliefs and are subject to risks, uncertainties and important factors that may cause actual events or results to differ materially, including uncertainties inherent in developing product candidates; interpreting the PreciSION CF results and potential confounding factors; the inherent limitations of post hoc analyses, which are exploratory and may not reliably predict future outcomes; the risk that in vitro and preclinical data may not translate to clinical benefit; the risk that results observed with one compound may not be predictive of results with a different compound or combination; and designing and conducting the planned Phase 2a trial.   Additional risks include the Company’s ability to demonstrate that its candidates are safe and effective; obtain regulatory feedback or approvals; achieve anticipated restructuring savings and runway extension; retain key personnel and capabilities following the workforce reduction; secure sufficient funding; and respond to general economic, industry and market conditions.   These risks and uncertainties are described in “Risk Factors” in Sionna’s most recent Quarterly Report on Form 10-Q and subsequent filings with the Securities and Exchange Commission. The events and circumstances reflected in the forward-looking statements may not be achieved or occur.   Any forward-looking statements represent Sionna’s views only as of today and should not be relied upon as representing its views as of any subsequent date. Sionna disclaims any obligation to update any forward-looking statements except as required by law. No representations or warranties, express or implied, are made about the accuracy of any such forward-looking statements.

Investor & Media Contact 
Juliet Labadorf 
ir@sionnatx.com 
media@sionnatx.com

FAQ

AI-generated questions and answers. How Rhea-AI works. Not financial advice.

What did Sionna's PreciSION CF trial show for SION-719 added to Trikafta?

The trial did not achieve its key activity endpoint, but post hoc analyses excluding three participants showed a mean placebo-adjusted sweat chloride reduction of 8.6 mmol/L. Those participants had pharmacokinetic patterns—patterns of drug exposure—consistent with dosing non-adherence.

What is the design of Sionna's planned AscenSION CF trial?

AscenSION CF is an open-label, 28-day Phase 2a proof-of-concept trial of SION-451 + SION-2222 in adults with cystic fibrosis who have two copies of F508del. It will assess sweat chloride, safety and pharmacokinetics, or drug exposure. Sionna expects it to begin in the first quarter of 2027.