Company: SION
Filing Date: 2025-01-17
Form Type: S-1
Source: 0001193125-25-008474
Chunk: 198

Company: Sionna Therapeutics, Inc.
Filing Date: 2025-01-17
Form: S-1
Chunk 198
---
, 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 of the preclinical tests, manufacturing information, analytical data and any available clinical data or literature and plans for clinical studies, among other things, to the FDA as part of an IND. An IND is a request for authorization from the FDA to grant an exemption that allows an unapproved drug to be shipped in 147

interstate commerce for use and administration in an investigational clinical trial for humans. The IND must become effective before human clinical trials may begin in the U.S. Some preclinical
testing, such as animal tests of reproductive adverse events and carcinogenicity, may continue even after the IND is submitted. An IND automatically becomes effective 30 days after receipt by the FDA, unless before that time the FDA raises concerns
or questions related to one or more proposed clinical trials and places the clinical trial on a clinical hold. A clinical hold is an order issued by the FDA to the sponsor to delay a proposed clinical investigation or to suspend an ongoing clinical
trial. Clinical holds may be imposed by the FDA when there is concern for patient safety, and may be a result of new data, findings or developments in clinical, nonclinical, and/or chemistry, manufacturing and controls or where there is non-compliance with regulatory requirements. A partial clinical hold is a delay or suspension of only part of the clinical work requested under the IND. Following issuance of a clinical hold or partial clinical
hold, an investigation (or full investigation in the case of a partial clinical hold) may only resume after the FDA has notified the sponsor that the investigation may proceed. As a