Company: SION
Filing Date: 2025-02-07
Form Type: 424B4
Source: 0001193125-25-022709
Chunk: 172

Company: Sionna Therapeutics, Inc.
Filing Date: 2025-02-07
Form: 424B4
Chunk 172
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 SION-451 is shown in Figures 16 and 17 below. The observed PK was
consistent with BID dosing.

Figure 16. Preliminary Phase 1 PK Summary for SION-451in the SAD Portion of the Trial

(Each solid line shows mean concentration data from a dosing cohort. Dotted lines represent average PK concentration exposure targets that have the potential, based on our preclinical CFHBE model, to provide clinically meaningful benefit, if SION-451 is administered in a proprietary dual combination with either SION-2222 or SION-109, or as an add-on to SOC.)

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Figure 17. Preliminary Phase 1 PK Summary for SION-451in the MAD Portion of the Trial

(Each solid line shows mean concentration data from a dosing cohort on Day 10. Dotted lines represent average PK concentration exposure targets that have the potential, based on our preclinical CFHBE model, to provide clinically meaningful benefit, if SION-451 is administered in a proprietary dual combination with either SION-2222 or SION-109, or as an add-on to SOC.)

Phase 2 Clinical Development Plans

Based on our current clinical development strategy, we anticipate conducting a Phase 2a add-on to Trikafta proof-of-concept trial and a Phase 2 dual combination treatment trial after the completion of our ongoing Phase 1 trials of SION-719
and SION-451. Our current expectations for our clinical development strategy are depicted in Figure 18 below.

Figure 18. Our Strategic Development Plan to Advance Our Pipeline of NBD1 Stabilizers and Complementary Modulators

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Phase 2a Proof-of-ConceptClinical Trial—NBD1 stabilizer + Trikafta

Following completion of our ongoing Phase 1 clinical trials of SION-719 and
SION-451, we plan to select a lead NBD1 stabilizer and conduct a drug-drug interaction trial before initiating a Phase 2a
proof-of-concept trial in CF patients. We expect the Phase 2a trial to be a two-way crossover trial in which we enroll up to 20
trial subjects with CF who are stable on physician-prescribed Trikafta. All trial subjects would be randomly allocated to one of two trial arms and continue taking Trikafta throughout the trial. Trial subjects in “Arm A” would first
receive Trikafta in combination with our lead NBD