Company: SION
Filing Date: 2025-02-03
Form Type: S-1/A
Source: 0001193125-25-018825
Chunk: 158

Company: Sionna Therapeutics, Inc.
Filing Date: 2025-02-03
Form: S-1/A
Chunk 158
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 4 below:

Figure 4. Our Proprietary Pipeline of Product Candidates for the Treatment of CF

Clinical trials for galicaftor, SION-2851, and navocaftor were conducted by AbbVie or Galapagos.

We have not obtained regulatory approval for any product candidate, and it is possible that we may never obtain regulatory approval for any product
candidates we may seek to develop in the future.

115

Our Strategy Our mission is to revolutionize the current treatment paradigm for CF patients by developing novel medicines that normalize the function of the CFTR protein to deliver clinically meaningful benefit to CF patients. The key pillars of our strategy are:

| • |     | Advance our novel NBD1 stabilizers. We are evaluating SION-719 and SION-451 in ongoing Phase 1 clinical trials to                                                                                                                                  
 assess their PK profile, safety and tolerability. In preclinical studies using the CFHBE model, the combination of SION-719 or SION-451 with one of our complementary modulators or ETI showed                                                     
 increased chloride transport, which indicates improvement in in vitro CFTR activity. Given the clinically predictive nature of the CFHBE model, we believe these data indicate the potential for an NBD1-anchored dual combination to improve CFTR 
 activity, which we believe will deliver clinically meaningful benefit to CF patients. Following completion of our ongoing Phase 1 clinical trials of SION-719 and                                                                                  
 SION-451, expected in the first half of 2025, we plan to select a lead NBD1 stabilizer and conduct a drug-drug interaction trial before initiating a Phase 2a proof-of-concept trial in CF patients.                                               |

| • |     | Develop and advance our pipeline of complementary modulators for proprietary combination product development. We are                                                                                                                                     
 developing a proprietary pipeline of complementary CFTR modulators designed to work synergistically with our NBD1 stabilizers to improve CFTR function, as seen in our CFHBE model. We have several CFTR modulators in development, including galicaftor 
 (SION-2222), a TMD1-directed corrector, which has recently completed a Phase 1 clinical trial.                                                                                                                                                           |

| • |     | Build upon our NBD1-centric CF franchise through a data-driven dual combination path. Our strategy is to                                                                                                                                               
 advance multiple NBD1 stabilizers and complementary compounds through Phase 1 development, with the goal of selecting the combinations with the best potential, based