Company: SION
Filing Date: 2025-02-03
Form Type: S-1/A
Source: 0001193125-25-018825
Chunk: 171

Company: Sionna Therapeutics, Inc.
Filing Date: 2025-02-03
Form: S-1/A
Chunk 171
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 vitroCFTR protein activity
of

126

F508del-CFTR to wild-type, or normal, levels. This was a more than 1.5-fold improvement in CFTR protein activity compared to the improvement in such activity observed with ETI at E in the same experiment. Based on predicted exposure levels in the CFHBE model, we believe co-administering SION-719 or SION-451 with a complementary modulator has the potential to achieve clinically meaningful benefit in CF patients.

In addition, we have nominated two NBD1 stabilizers with differentiated profiles as development candidates.

SION-719and SION-451

Phase 1 Clinical Development

We
initiated Phase 1 SAD and MAD clinical trials of SION-719 and SION-451 in healthy subjects in July 2024 and August 2024, respectively. These trials are randomized,
doubled-blinded, placebo-controlled trials designed to evaluate safety, tolerability and PK of each product candidate. Both trials are being conducted in Australia. In a Part C of each Phase 1 trial, we plan to evaluate the effect of food on the PK
of each product candidate and the bioequivalence of a tablet formation compared to the oral suspension administered in the Phase 1 SAD and MAD trials. We intend to enroll up to 120 healthy volunteers in each trial. We expect topline data for these
trials in the first half of 2025.

Interim Phase 1 Trial Data for SION-719

As of January 14, 2025, over 60 healthy subjects have been dosed in the Phase 1 clinical trial of SION-719. The
trial was designed to enroll eight subjects, randomized 3:1 active:placebo, in each dosing cohort. Five SAD cohorts have been completed, evaluating single doses of 20 mg, 40 mg, 80 mg, 160 mg and 20 mg taken with food to provide a preliminary
assessment of the effect of food on PK. Three MAD cohorts have been completed, evaluating 20 mg, 40 mg and 80 mg of SION-719 twice daily over 10 dosing days, and the next MAD cohort will evaluate 160 mg
twice daily over 10 dosing days. We plan to continue enrolling healthy subjects in the trial. All data remain blinded to individual subject treatment assignment, with the exception of selected individual subjects unblinded for administrative
and study planning purposes according to