Sionna Therapeutics, Inc.

Previous wording

We are a clinical-stage biopharmaceutical company and have incurred significant operating losses since inception and anticipate that we will continue to incur significant operating losses for the foreseeable future. Our net losses were $26.8 million and $16.5 million for the three months ended March 31, 2026, and 2025, respectively. We had an accumulated deficit of $283.1 million as of March 31, 2026. We may never achieve or maintain profitability.

Current wording

We are a clinical-stage biopharmaceutical company and have incurred significant operating losses since inception and anticipate that we will continue to incur significant operating losses for the foreseeable future. Our net losses were $56.7 million and $34.6 million for the six months ended June 30, 2026, and 2025, respectively. We had an accumulated deficit of $313.0 million as of June 30, 2026. We may never achieve or maintain profitability.

Previous wording

We are a clinical-stage biopharmaceutical company with a limited operating history. We have incurred operating losses in each year since our inception. Our net losses were $26.8 million and $16.5 million for the three months ended March 31, 2026, and 2025, respectively. We had an accumulated deficit of $283.1 million as of March 31, 2026. Substantially all of our operating losses have resulted from costs incurred in connection with our research and development programs and from general and administrative costs associated with our operations. Our prior losses, combined with expected future losses, have had and will continue to have an adverse effect on our stockholders’ equity and working capital.

Current wording

We are a clinical-stage biopharmaceutical company with a limited operating history. We have incurred operating losses in each year since our inception. Our net losses were $56.7 million and $34.6 million for the six months ended June 30, 2026, and 2025, respectively. We had an accumulated deficit of $313.0 million as of June 30, 2026. Substantially all of our operating losses have resulted from costs incurred in connection with our research and development programs and from general and administrative costs associated with our operations. Our prior losses, combined with expected future losses, have had and will continue to have an adverse effect on our stockholders’ equity and working capital.

Previous wording

As of March 31, 2026, we had cash, cash equivalents and marketable securities of $289.9 million. We believe that, based upon our current operating plans, our existing cash, cash equivalents and marketable securities will be sufficient to fund our operations into 2028. This estimate is based on assumptions that may prove to be wrong, and we could use our available capital resources sooner than we expect. Changes may occur beyond our control that would cause us to consume our available capital before that time, including but not limited to changes in progress of our development activities, acquisitions of additional product candidates and changes in regulations. Our future capital requirements will depend on, and could increase significantly as a result of, many factors, including:

Current wording

As of June 30, 2026, we had cash, cash equivalents and marketable securities of $268.3 million. We believe that, based upon our current operating plans, our existing cash, cash equivalents and marketable securities will be sufficient to fund our operations into 2028. This estimate is based on assumptions that may prove to be wrong, and we could use our available capital resources sooner than we expect. Changes may occur beyond our control that would cause us to consume our available capital before that time, including but not limited to changes in progress of our development activities, acquisitions of additional product candidates and changes in regulations. Our future capital requirements will depend on, and could increase significantly as a result of, many factors, including:

Previous wording

To date, as an organization, we have not completed the development of any product candidates. We are substantially dependent on the success of at least one of our NBD1 stabilizer product candidates, SION-719 and SION-451, which are currently in development for the treatment of cystic fibrosis ("CF"). Our NBD1 stabilizers are being developed for use either in combination with one of our complementary modulator candidates or the standard of care. We are currently evaluating SION-719 in a Phase 2a proof-of-concept clinical trial as an add-on to the standard of care for CF and SION-451 in a Phase 1 dual combination trial with each of our two most advanced complementary modulator candidates, galicaftor (SION-2222) and SION-109.

Current wording

To date, as an organization, we have not completed the development of any product candidates. We are substantially dependent on the success of at least one of our NBD1 stabilizer product candidates, SION-719 and SION-451, which are currently in development for the treatment of cystic fibrosis ("CF"). Our NBD1 stabilizers are being developed for use either in combination with one of our complementary modulator candidates or the standard of care. We expect to report in the summer of 2026 topline data from a Phase 2a proof-of-concept clinical trial evaluating SION-719 as an add-on to the standard of care for CF and a Phase 1 trial evaluating SION-451 in dual combinations with each of galicaftor (SION-2222) and SION-109.

Previous wording

The current treatment paradigm in CF for all patients with the F508del mutation is based on a combination of drug therapies. We are currently evaluating SION-719 in combination with the standard of care in a Phase 2a proof-of-concept trial in CF patients, which we initiated in October 2025. We are also currently evaluating SION-451 in dual combinations with our two most advanced complementary modulator candidates, SION-2222 and SION-109, in a Phase 1 trial in healthy volunteers. The development of a proprietary dual combination is our prioritized development path. In either development scenario, the use of our product candidates in combination with each other or with an approved product may subject us to risks that we would not face if our product candidates were being developed to be administered as a monotherapy.

Current wording

The current treatment paradigm in CF for all patients with the F508del mutation is based on a combination of drug therapies. We expect to report in the summer of 2026 topline data from a Phase 2a proof-of-concept trial in CF patients evaluating SION-719 in combination with the standard of care and a Phase 1 trial evaluating SION-451 in dual combinations with SION-2222 and SION-109. The development of a proprietary dual combination is our prioritized development path. In either development scenario, the use of our product candidates in combination with each other or with an approved product may subject us to risks that we would not face if our product candidates were being developed to be administered as a monotherapy.

Previous wording

Further, others, including regulatory agencies, may not accept or agree with our assumptions, estimates, calculations, conclusions or analyses or may interpret or weigh the importance of data differently, which could impact the value of the particular program, the approvability or commercialization of the particular product candidate or product and our company in general. In addition, the information we choose to publicly disclose regarding a particular study or clinical trial is based on what is typically extensive information, and investors or others may not agree with what we determine is material or otherwise appropriate information to include in our disclosure. If the interim, topline or preliminary data that we report differ from actual results, or if others, including regulatory authorities, disagree with the conclusions reached, our ability to obtain approval for, and commercialize, our product candidates may be harmed, which could harm our business, operating results, prospects or financial condition.

Current wording

Further, others, including regulatory agencies, may not accept or agree with our assumptions, estimates, calculations, conclusions or analyses or may interpret or weigh the importance of data differently, which could impact the value of the particular program, the approvability or commercialization of the particular product candidate or product and our company in general. In addition, the information we choose to publicly disclose regarding a particular study or clinical trial is based on what is typically extensive information, and investors or others may not agree with what we determine is material or otherwise appropriate information to

Previous wording

Even in the absence of obtaining Fast Track and/or Breakthrough Therapy Designations, a sponsor can seek priority review at the time of submitting a marketing application. The FDA may designate a product for priority review if it is a product that treats a serious condition and, if approved, would provide a significant improvement in safety or effectiveness when compared with other available therapies. Significant improvement may be illustrated by evidence of increased effectiveness in the treatment of a condition, elimination or substantial reduction of a treatment-limiting adverse reaction, documented enhancement of patient compliance that may lead to improvement in serious outcomes, or evidence of safety and effectiveness in a new subpopulation. A priority review designation is intended to direct overall attention and resources to the evaluation of such applications, and to shorten the FDA’s goal for taking action on a marketing application from ten months to six months from FDA’s acceptance of the application for review. Priority review designation may be rescinded if a product no longer meets the qualifying criteria.

Current wording

ten months to six months from FDA’s acceptance of the application for review. Priority review designation may be rescinded if a product no longer meets the qualifying criteria.

Previous wording

Our reliance on CDMOs for manufacturing activities reduces our control over these activities, but does not relieve us of our responsibility to ensure compliance with all required regulations. In particular, we do not have control over a supplier’s or manufacturer’s compliance with laws, regulations and applicable cGMP standards or similar regulatory requirements and other laws and regulations, such as those related to environmental health and safety matters. If our CDMOs cannot successfully manufacture material that conforms to our specifications and the strict regulatory requirements of the FDA or comparable foreign regulatory authorities, we may be unable to obtain regulatory approval of our potential future marketing applications. In addition, although we conduct routine qualification audits and have quality agreements in place with our CDMOs, we have no direct operational control over their ability to maintain adequate quality control, quality assurance and qualified personnel. Our CDMOs may face manufacturing or quality control problems causing production and shipment delays, or CDMOs may fail to maintain compliance with the applicable cGMP requirements. The facilities used by our CDMOs are subject to continual review and periodic inspections by the FDA and comparable foreign regulatory authorities. If the FDA or a comparable foreign regulatory authority finds deficiencies with or does not approve these facilities for the manufacture of our product candidates or if it withdraws any such approval in the future, we may need to find alternative manufacturing facilities, which would significantly impact our ability to develop, obtain regulatory approval for or market our product candidates, if approved. Our failure, or the failure of our third-party manufacturers, to comply with applicable regulations could result in sanctions being imposed on us, including clinical holds, fines, injunctions, civil penalties, delays, suspension or withdrawal of approvals, license revocation, seizures or recalls of product candidates or drugs, operating restrictions and criminal prosecutions, any of which could significantly and adversely affect supply of our products.

Current wording

Our reliance on CDMOs for manufacturing activities reduces our control over these activities, but does not relieve us of our responsibility to ensure compliance with all required regulations. In particular, we do not have control over a supplier’s or manufacturer’s compliance with laws, regulations and applicable cGMP standards or similar regulatory requirements and other laws and regulations, such as those related to environmental health and safety matters. If our CDMOs cannot successfully manufacture material that conforms to our specifications and the strict regulatory requirements of the FDA or comparable foreign regulatory authorities, we may be unable to obtain regulatory approval of our potential future marketing applications. Although we conduct routine qualification audits and have quality agreements in place with our CDMOs, we have no direct operational control over their ability to maintain adequate quality control, quality assurance and qualified personnel. Our CDMOs may face manufacturing or quality control problems causing production and shipment delays, or CDMOs may fail to maintain compliance with the applicable cGMP requirements. The facilities used by our CDMOs are subject to continual review and periodic inspections by the FDA and comparable foreign regulatory authorities. If the FDA or a comparable foreign regulatory authority finds deficiencies with or does not approve these facilities for the manufacture of our product candidates or if it withdraws any such approval in the future, we may need to find alternative manufacturing facilities, which would significantly impact our ability to develop, obtain regulatory approval for or market our product candidates, if approved. Our failure, or the failure of our third-party manufacturers, to comply with applicable regulations could result in sanctions being imposed on us, including clinical holds, fines, injunctions, civil penalties, delays, suspension or withdrawal of approvals, license revocation, seizures or recalls of product candidates or drugs, operating restrictions and criminal prosecutions, any of which could significantly and adversely affect supply of our products.

Previous wording

Our use of foreign CROs and CDMOs in some jurisdictions may be or may become subject to U.S. legislation, sanctions, tariffs, trade restrictions and/or other regulatory requirements, which may increase the cost of and cause delays in the procurement or supply of materials for, or manufacture of, our product candidates or have an adverse effect on our ability to secure significant commitments from governments to purchase our potential therapies. For example, legislation recently signed into law, known as the BIOSECURE Act, implements a prohibition on U.S. government contracts, grants, and loans from being used towards biotechnology equipment and services produced or provided by certain identified Chinese biotechnology companies and authorizes the U.S. government to name additional Chinese biotechnology companies of concern. By December 18, 2026, the Director of the Office of Management and Budget ("OMB"), will publish a full list of "biotechnology companies of concern" based on recommendations from key federal Secretaries and Directors, including Defense, Justice, HHS, Commerce, National Intelligence, Homeland Security, State, and National Cyber. The Director of OMB will thereafter review and update that list at least annually, based on recommendations from those key federal Secretaries and Directors. We have an agreement with a Chinese biotechnology company, pursuant to which it may manufacture certain of our clinical trial materials from time to time. This Chinese company was initially identified as a "biotechnology company of concern" in an earlier proposed version of the BIOSECURE Act, but that legislation did not pass, and the company is not named in the final law; however, it could be added in the future. The BIOSECURE Act has the potential to severely restrict the ability of companies, including us, to work with certain Chinese biotechnology companies of concern without losing the ability to contract with, or otherwise receive funding from, the U.S. government. Additionally, our use of foreign CROs and CDMOs, including those located in China, may be subject to unanticipated changes in the geopolitical landscape that could have negative impacts on our business operations.

Current wording

Our use of foreign CROs and CDMOs in some jurisdictions may be or may become subject to U.S. legislation, sanctions, tariffs, trade restrictions and/or other regulatory requirements, which may increase the cost of and cause delays in the procurement or supply of materials for, or manufacture of, our product candidates or have an adverse effect on our ability to secure significant commitments from governments to purchase our potential therapies. For example, legislation recently signed into law, known as the BIOSECURE Act, implements a prohibition on U.S. government contracts, grants, and loans from being used towards biotechnology equipment and services produced or provided by "biotechnology companies of concern." By December 18, 2026, the Director of the Office of Management and Budget ("OMB"), will publish a full list of biotechnology companies of concern based on recommendations from key federal Secretaries and Directors, including Defense, Justice, HHS, Commerce, National Intelligence, Homeland Security, State, and National Cyber. The Director of OMB will thereafter review and update that list at least annually, based on recommendations from those key federal Secretaries and Directors. We have an agreement with a Chinese biotechnology company, pursuant to which it may manufacture certain of our clinical trial materials from time to time. On June 8, 2026, the Department of Defense added this Chinese company to the Section 1260H list, which may result in the company being designated a biotechnology company of concern under the BIOSECURE Act once OMB publishes its list. The company has disputed its inclusion on the 1260H list and has stated it intends to pursue available remedies to contest the designation. The outcome of any such challenge is uncertain. The BIOSECURE Act has the potential to severely restrict the ability of companies, including us, to work with certain Chinese biotechnology companies of concern without losing the ability to contract with, or otherwise receive funding from, the U.S. government. If the company with which we have an agreement is ultimately designated as a biotechnology company of concern, we may need to transition to alternative suppliers, which could be costly, time-consuming and disruptive to our clinical development programs. Additionally, our use of foreign CROs and CDMOs, including those located in China, may be subject to unanticipated changes in the geopolitical landscape that could have negative impacts on our business operations.

Previous wording

While no third parties to our knowledge have initiated legal proceedings against us to date, as our current and future product candidates progress toward commercialization, the possibility of a patent infringement claim against us increases. We cannot provide any assurance that our current and future product candidates do not infringe other parties’ patents or other proprietary rights, and competitors or other parties may assert that we infringe their proprietary rights in any event. We may become party to, or threatened with, adversarial proceedings or litigation regarding intellectual property rights with respect to our current and future product candidates, including infringement, interference or derivation proceedings, post-grant review andinter partes review before the USPTO or similar adversarial proceedings or litigation in other jurisdictions. Even if we believe such claims are without merit, a court of competent jurisdiction could hold that these third-party patents are valid, enforceable and infringed, which could have a negative impact on our ability to commercialize our product candidates or any future product candidates. In order to successfully challenge the validity of any such U.S. patent in federal court, we would need to overcome a presumption of validity. As this burden is high and requires us to present clear and convincing evidence as to the invalidity of any such U.S. patent claim, there is no assurance that a court of competent jurisdiction would agree with us and invalidate the claims of any such U.S. patent. Similarly, the burdens on us to invalidate patent claims in foreign jurisdiction may vary substantially and courts in those jurisdictions may not agree with us that the claims are invalid. The outcome of proceedings involving assertions of infringement, invalidity and unenforceability during patent litigation is unpredictable. Furthermore, if a patent holder believes that one of our product candidates infringes its patent, the patent holder may sue us even if we have received patent protection for our intellectual property. Moreover, we may face patent infringement claims from non-practicing entities that have no relevant revenue and against whom our own patent portfolio may thus have no deterrent effect. If a patent infringement suit were threatened or brought against us, we could be forced to stop or delay manufacturing or sales of the drug or product candidate that is the subject of the actual or threatened suit. Moreover, given the vast number of patents in our field of intellectual property, we cannot be certain that our current and future product candidates do not or will not infringe existing patents or that we will not infringe patents that may be granted in the future.

Current wording

While no third parties to our knowledge have initiated legal proceedings against us to date, as our current and future product candidates progress toward commercialization, the possibility of a patent infringement claim against us increases. We cannot provide any assurance that our current and future product candidates do not infringe other parties’ patents or other proprietary rights, and competitors or other parties may assert that we infringe their proprietary rights in any event. We may become party to, or threatened with, adversarial proceedings or litigation regarding intellectual property rights with respect to our current and future product candidates, including infringement, interference or derivation proceedings, post-grant review andinter partes review before the USPTO or similar adversarial proceedings or litigation in other jurisdictions. We are currently in settlement discussions with a third party regarding a trademark opposition in Peru, which we do not consider to be material. Even if we believe such claims are without merit, a court of competent jurisdiction could hold that these third-party patents are valid, enforceable and infringed, which could have a negative impact on our ability to commercialize our product candidates or any future product candidates. In order to successfully challenge the validity of any such U.S. patent in federal court, we would need to overcome a presumption of validity. As this burden is high and requires us to present clear and convincing evidence as to the invalidity of any such U.S. patent claim, there is no assurance that a court of competent jurisdiction would agree with us and invalidate the claims of any such U.S. patent. Similarly, the burdens on us to invalidate patent claims in foreign jurisdiction may vary substantially and courts in those jurisdictions may not agree with us that the claims are invalid. The outcome of proceedings involving assertions of infringement, invalidity and unenforceability during patent litigation is unpredictable. Furthermore, if a patent holder believes that one of our product candidates infringes its patent, the patent holder may sue us even if we have received patent protection for our intellectual property. Moreover, we may face patent infringement claims from non-practicing entities that have no relevant revenue and against whom our own patent portfolio may thus have no deterrent effect. If a patent infringement suit were threatened or brought against us, we could be forced to stop or delay manufacturing or sales of the drug or product candidate that is the subject of the actual or threatened suit. Moreover, given the vast number of patents in our field of intellectual property, we cannot be certain that our current and future product candidates do not or will not infringe existing patents or that we will not infringe patents that may be granted in the future.

Previous wording

The U.S. has recently taken steps intended to reduce drug prices and establish and communicate most-favored-nation price targets to pharmaceutical manufacturers to bring prices for American patients in line with comparably developed nations. Several large pharmaceutical companies have already started to voluntarily reduce their pricing on select drugs indexed to lower prices around the globe. In addition, at the state level, legislatures have increasingly passed legislation and implemented regulations with similar goals, as well as laws designed to control pharmaceutical and biotherapeutic product pricing, including restrictions on pricing or reimbursement at the state government level, limitations on discounts to patients, marketing cost disclosure and transparency measures, restrictions or other limitations on patient assistance, and, in some cases, policies to encourage importation from other countries (subject to federal approval) and bulk purchasing.

Current wording

The U.S. has recently taken steps intended to reduce drug prices and establish and communicate most-favored-nation price targets to pharmaceutical manufacturers to bring prices for American patients in line with comparably developed nations, including recently proposed most-favored-nation Medicare reimbursement models issued by the Centers for Medicare and Medicaid Services. In addition, several large pharmaceutical companies have already started to voluntarily reduce their pricing on select drugs indexed to lower prices around the globe. At the state level, legislatures have increasingly passed legislation and implemented regulations with similar goals, as well as laws designed to control pharmaceutical and biotherapeutic product pricing, including restrictions on pricing or reimbursement at the state government level, limitations on discounts to patients, marketing cost disclosure and transparency measures, restrictions or other limitations on patient assistance, and, in some cases, policies to encourage importation from other countries (subject to federal approval) and bulk purchasing.

Previous wording

Our estimates of the potential market opportunity for our product candidates include several key assumptions, based on our industry knowledge, industry publications and third-party research reports. These assumptions include the number of patients who have CF, as well as the estimated reimbursement levels for each product candidate, if approved. While we believe our assumptions and the data underlying our estimates are reasonable, we have not independently verified the accuracy of the third-party data on which we have based our assumptions and estimates, and these assumptions and estimates may not be correct and the conditions supporting our assumptions or estimates may change at any time, including as a result of factors outside our control, thereby reducing the predictive accuracy of these underlying factors. Further, new studies may change the estimated incidence or prevalence of these diseases, and the potentially addressable patient population for our product candidates may not ultimately be amenable to treatment with our product candidates. If the actual market for any product candidates we may develop is smaller than we estimate, our revenues, if any, may be limited and it may be more difficult for us to achieve or maintain profitability.

Current wording

Our estimates of the potential market opportunity for our product candidates include several key assumptions, based on our industry knowledge, industry publications and third-party research reports. These assumptions include the number of patients who have CF, as well as the estimated reimbursement levels for each product candidate, if approved. While we believe our assumptions and the data underlying our estimates are reasonable, we have not independently verified the accuracy of the third-party data on which we have based our assumptions and estimates, and these assumptions and estimates may not be correct and the conditions supporting our assumptions or estimates may change at any time, including as a result of factors outside our control, thereby reducing the predictive accuracy of these underlying factors. Further, new studies may change the estimated incidence or prevalence of these diseases, and the potentially addressable patient population for our product candidates may not ultimately be amenable to treatment with our product candidates.

Previous wording

We cannot predict if investors will find our common stock less attractive because we will rely on these exemptions. If some investors find our common stock less attractive as a result, there may be a less active trading market for our common stock and our stock price may be more volatile. We will remain an emerging growth company until the earlier of (1) the last day of the fiscal year (a) following the fifth anniversary of the closing of our initial public offering, (b) in which we have total annual gross revenue of at least $1.235 billion or (c) in which we are deemed to be a large accelerated filer, which means, among other conditions, that the market value of our common stock that is held by non-affiliates exceeds $700 million as of the last business day of our most recently completed second fiscal quarter, and (2) the date on which we have issued more than $1.0 billion in non-convertible debt during the prior three-year period.

Current wording

We will remain an emerging growth company until the earlier of (1) the last day of the fiscal year (a) following the fifth anniversary of the closing of our initial public offering, (b) in which we have total annual gross revenue of at least $1.235 billion or (c) in which we are deemed to be a large accelerated filer, which means, among other conditions, that the market value of our common stock that is held by non-affiliates exceeds $700 million as of the last business day of our most recently completed second fiscal quarter, and (2) the date on which we have issued more than $1.0 billion in non-convertible debt during the prior three-year period. Under

Previous wording

Under Section 107(b) of the JOBS Act, emerging growth companies can delay adopting new or revised accounting standards until such time as those standards apply to private companies, and we expect to rely on this exemption. Even after we no longer qualify as an emerging growth company, we may, under certain circumstances, still qualify as a “smaller reporting company,” which would allow us to take advantage of many of the same exemptions from disclosure requirements, including reduced disclosure obligations regarding executive compensation in our periodic reports and proxy statements.

Current wording

Section 107(b) of the JOBS Act, emerging growth companies can delay adopting new or revised accounting standards until such time as those standards apply to private companies, and we rely on this exemption.