Company: SION
Filing Date: 2025-01-17
Form Type: S-1
Source: 0001193125-25-008474
Chunk: 156

Company: Sionna Therapeutics, Inc.
Filing Date: 2025-01-17
Form: S-1
Chunk 156
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| • |     | Galicaftor (SION-2222) and SION-2851 are TMD1-directed CFTR correctors. Galicaftor was generally well-tolerated in Phase 1                                                                                                                  
 and Phase 2 trials, and improvement in sweat chloride as a monotherapy and improvements in sweat chloride and lung function as a combination therapy with navocaftor were observed. SION-2851 has completed a Phase 1 single ascending dose 
 (“SAD”) trial in healthy volunteers.                                                                                                                                                                                                        |

| • |     | SION-109, an ICL4-directed CFTR corrector, has been evaluated in a recently                                                                                                                                                                       
 completed Phase 1 clinical trial in healthy volunteers. SION-109 was generally well tolerated at all dose levels administered in all parts of this Phase 1 trial. The target exposure for SION-109 as part of a dual combination with SION-451 or 
 SION-719 was achieved with single and multiple dose.                                                                                                                                                                                              |

| • |     | Navocaftor (SION-3067), a potentiator, has been evaluated in Phase 2 trials, in which it demonstrated potential as a 
 combination therapy.                                                                                                 |

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Figure 3 below captures the targeted binding locations within the CFTR structure for our pipeline of
NBD1 stabilizers and complementary modulators.

Figure 3. Our Multi-Prong Approach to Potentially Improving CFTR Function

Our current portfolio of programs is summarized in Figure 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.

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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