Company: SION
Filing Date: 2025-02-07
Form Type: 424B4
Source: 0001193125-25-022709
Chunk: 55

Company: Sionna Therapeutics, Inc.
Filing Date: 2025-02-07
Form: 424B4
Chunk 55
---
 as an acquisition, that divert 
 resources or create competing priorities;                                                                                                                                                                                                     |

| • |     | collaborators may delay clinical trials, provide insufficient funding for a clinical trial program, stop a clinical trial                       
 or abandon a product candidate, repeat or conduct new clinical trials or require a new formulation of a product candidate for clinical testing; |

| • |     | collaborators could independently develop, or develop with third parties, products that compete directly or indirectly with                                                                                      
 our product candidates if the collaborators believe that competitive products are more likely to be successfully developed or can be commercialized under terms that are more economically attractive than ours; |

| • |     | a collaborator with marketing and distribution rights to one or more of our product candidates that achieve regulatory 
 approval may not commit sufficient resources to the marketing and distribution of such products;                       |

| • |     | disagreements with collaborators, including disagreements over proprietary rights, contract interpretation or the preferred                                                                                                                             
 course of development, might cause delays or termination of the research, development or commercialization of product candidates, might lead to additional responsibilities for us with respect to product candidates, or might result in litigation or 
 arbitration, any of which would be time-consuming and expensive;                                                                                                                                                                                        |

| • |     | collaborators may not properly maintain or defend our or their intellectual property rights or may use our or their                                                                           
 proprietary information in such a way as to invite litigation that could jeopardize or invalidate such intellectual property or proprietary information or expose us to potential litigation; |

| • |     | collaborators may infringe the intellectual property rights of third parties, which may expose us to litigation and 
 potential liability; and                                                                                            |

| • |     | collaborations may be terminated, including for the convenience of the collaborator and, if terminated, we could be           
 required to raise additional capital to pursue further development or commercialization of the applicable product candidates. |

41

We may not be able to negotiate future collaborations on a timely basis, on acceptable terms, or at
all. If we are unable to do so, we may have to curtail the development of any product candidate that we planned to collaborate on, reduce or delay its development program or one or more of our other development programs, delay its potential
commercialization or reduce the scope of any sales or marketing activities, or increase our expenditures and undertake development or commercialization activities at our own expense. If we elect to increase our expenditures to fund development or
commercialization activities on our own, we may need to obtain additional capital, which may not be available