Company: SION
Filing Date: 2025-01-17
Form Type: S-1
Source: 0001193125-25-008474
Chunk: 170

Company: Sionna Therapeutics, Inc.
Filing Date: 2025-01-17
Form: S-1
Chunk 170
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 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. 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 the clinical trial protocol.

SION-719 was generally well tolerated at all dose levels administered based on interim Phase 1 clinical data as of the data cutoff date of January 14,
2025. There were no serious adverse events (“SAEs”). Most treatment-emergent adverse events (“TEAEs”) were mild to moderate (Grade 1 or Grade 2). No TEAEs led to the discontinuation of trial drug. The most common TEAEs, occurring
in >1 subject, were headache, hypoglycemia and diarrhea. All TEAEs occurring in >1 subject were Grade 1 or Grade 2, except a single Grade 4 hypoglycemia TEAE in a placebo subject in a SAD cohort. There were no TEAEs related to liver function
tests. No dose-limiting TEAEs or safety trends of concern have been observed.

Increasing exposure was observed with increasing single and multiple
doses. The concentration targets for SION-719 as an add-on to SOC and as part of a dual combination with SION-2222 or