Company: SION
Filing Date: 2025-02-03
Form Type: S-1/A
Source: 0001193125-25-018825
Chunk: 199

Company: Sionna Therapeutics, Inc.
Filing Date: 2025-02-03
Form: S-1/A
Chunk 199
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 the following:

| • |     | completion of extensive nonclinical, or preclinical, laboratory tests, animal studies and formulation studies in compliance 
 with the FDA’s Good Laboratory Practice (“GLP”) regulations;                                                                |

| • |     | submission to the FDA of an IND, which must become effective before human clinical trials may begin and must be updated 
 annually and when certain changes are made;                                                                             |

| • |     | approval by an institutional review board (“IRB”) or independent ethics committee (“IEC”) at each 
 clinical site before each trial may be initiated at that site;                                    |

| • |     | performance of adequate and well-controlled human clinical trials in accordance with Good Clinical Practices                                                             
 (“GCP”) requirements and other clinical trial-related regulations to establish the safety and efficacy of the investigational drug product for each proposed indication; |

| • |     | preparation and submission to the FDA of an NDA after completion of all pivotal trials, together with the payment of 
 application user fees, as applicable;                                                                                |

| • |     | a determination by the FDA within 60 days of its receipt of an NDA to accept the marketing application for review; |

| • |     | satisfactory completion of an FDA advisory committee review, if applicable; |

| • |     | satisfactory completion of one or more FDA inspections of the manufacturing facility or facilities at which the product is                                                                  
 produced to assess compliance with cGMP requirements and to assure that the facilities, methods and controls are adequate to preserve the product’s identity, strength, quality and purity; |

| • |     | satisfactory completion of FDA audits of clinical trial sites to assure compliance with GCPs and the integrity of the 
 clinical data; and                                                                                                    |

| • |     | FDA review and approval of the NDA. |

Preclinical Studies Before testing any drug product candidate, including our product candidates, in humans, the product candidate must undergo rigorous preclinical testing. Preclinical studies include laboratory evaluations of the product’s chemistry, purity, toxicity, formulation, and stability as well as in vitroand animal studies to assess potential safety and efficacy and in some cases to establish the rationale for therapeutic use. The conduct of preclinical studies is subject to federal regulations and requirements, including GLP regulations for safety and toxicology studies. The IND and IRB Process Prior to beginning the first clinical trial with a product candidate in the U.S., we must submit an IND to the FDA. An IND sponsor must submit a protocol for each clinical trial, the results