Company: SION
Filing Date: 2025-01-17
Form Type: S-1
Source: 0001193125-25-008474
Chunk: 200

Company: Sionna Therapeutics, Inc.
Filing Date: 2025-01-17
Form: S-1
Chunk 200
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Regulatory
authorities, the IRB or the sponsor may suspend a clinical trial at any time on various grounds, including a finding that the subjects are being exposed to an unacceptable health risk or that the trial is unlikely to meet its stated objectives. Some
studies also include oversight by an independent

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group of qualified experts organized by the clinical study sponsor, known as a data and safety monitoring board (“DSMB”), which provides authorization for whether or not a study may move forward at designated check points based on access to certain data from the study and may halt the clinical trial if it determines that there is an unacceptable safety or health risk for subjects or other grounds, such as no demonstration of efficacy. Information about certain clinical trials must be submitted within specific timeframes to the National Institutes of Health (“NIH”) for public dissemination on their www.clinicaltrials.govwebsite. Information related to the investigational product, patient population, phase of investigation, study sites and investigators and 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