Company: SION
Filing Date: 2025-02-03
Form Type: S-1/A
Source: 0001193125-25-018825
Chunk: 202

Company: Sionna Therapeutics, Inc.
Filing Date: 2025-02-03
Form: S-1/A
Chunk 202
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 other aspects of the clinical trial is made public as part of the registration of the clinical trial. Although sponsors are obligated to disclose the results of their clinical trials after completion, disclosure of the results can be delayed in some cases for some time. Failure to timely register a covered clinical study or to submit study results as provided for in the law can give rise to civil monetary penalties and also prevent the non-compliantparty from receiving future grant funds from the federal government. Human clinical trials are typically conducted in three sequential phases, which may overlap or be combined:

| • |     | Phase 1: The investigational drug is initially introduced into a limited population of healthy human subjects or, in                                                                                                                           
 certain indications such as cancer, patients with the target disease or condition and tested for safety, dosage tolerance, absorption, metabolism, distribution, excretion, side effects, and, if possible, to gain an early indication of its 
 effectiveness or determine optimal dosage.                                                                                                                                                                                                     |

| • |     | Phase 2: The investigational drug is administered to a limited patient population with a specified disease or condition to                                                                                                                          
 identify possible adverse effects and safety risks, to preliminarily evaluate the efficacy of the product for specific targeted diseases and to determine dosage tolerance and optimal dosage. Multiple Phase 2 clinical trials may be conducted to 
 obtain information prior to beginning Phase 3 clinical trials.                                                                                                                                                                                      |

| • |     | Phase 3: The investigational drug is administered to an expanded patient population, generally at geographically dispersed                                                                                                                            
 clinical trial sites, in well-controlled clinical trials to generate enough data to statistically evaluate the efficacy and safety of the product for approval, to establish the overall risk/benefit profile of the product, and to provide adequate 
 information for product approval and labeling of the product. Generally, two adequate and well-controlled Phase 3 clinical trials are required by the FDA for approval of an NDA.                                                                     |

Post-approval trials, sometimes referred to as Phase 4 clinical trials, may be conducted after initial marketing approval. These trials are used to gain additional experience from the treatment of patients in the intended therapeutic indication and are commonly intended to generate additional safety data regarding use of the product in a clinical setting. In certain instances, the FDA may mandate the performance of Phase 4 clinical trials as a condition of approval on an NDA. Progress reports detailing the results of the clinical trials must be submitted at least annually to the FDA and more frequently if serious adverse events occur. In addition, within 15 calendar days after the