Company: SION
Filing Date: 2025-02-07
Form Type: 424B4
Source: 0001193125-25-022709
Chunk: 36

Company: Sionna Therapeutics, Inc.
Filing Date: 2025-02-07
Form: 424B4
Chunk 36
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 predictive of clinical outcomes for approved CFTR modulators. In preclinical studies
using our CFHBE model, the combination of either SION-719 or SION-451 with one of our complementary modulators or the components of Trikafta showed significant improvement in in vitro CFTR activity and
the potential for restoration of CFTR function to wild-type levels. However, we have not yet replicated such results in clinical trials, and our product candidates may fail to show the desired safety and efficacy at the dose ranges we have
identified using our CFHBE model. Positive results in our preclinical studies using our CFHBE model may not be predictive of the results in clinical trials and may fail to be replicated in clinical trials.

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

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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.

Targeting the NBD1 domain of the CFTR protein is novel, and we do not know whether we will be able to successfully develop any products.

Our NBD1 stabilizer product candidates target the NBD1
domain of the CFTR protein, which is a novel target. Other companies have discontinued programs targeting NBD1 as they were unable to develop compounds that could successfully bind to NBD1. We intend to develop one of our NBD1 stabilizers as a
combination therapy with either one of our complementary modulators, galicaftor or SION-109, or as an add-on to the current standard of care. Given the novelty of our
product candidates and the inherent risk in developing a combination or add-on therapy, we may not be able to successfully develop any products.

While products modulating the CFTR protein have been approved by the FDA and comparable