SION - 1Q26; Both Phase IIa PreciSION & Phase I Dual Combo Studies Remain On-Track For Summer 2026 (Aug/Sep) - We See 2-3x Potential Upside On Positive Results

Research evidence excerpt

SION - 1Q26; Both Phase IIa PreciSION & Phase I Dual Combo Studies Remain On-Track For Summer 2026 (Aug/Sep) - We See 2-3x Potential Upside On Positive Results

May 12, 2026

Yatin Suneja yatin.suneja@guggenheimpartners.com SION - 1Q26; Both Phase IIa PreciSION & Phase I

212 518 9565 Dual Combo Studies Remain On-Track For Summer

Min Lee, Ph.D.

min.lee@guggenheimpartners.com 2026 (Aug/Sep) - We See 2-3x Potential Upside On

212 823 6744 Positive Results Eddie Hickman, Ph.D.

eddie.hickman@guggenheimpartners.com

212 518 9904 Key Message: This morning, SION announced 1Q26 earnings. The company ended

Delma Caiati, M.D., Ph.D. 1Q26 with $289.9MM in cash and guided cash runway until 2028. Key updates are:

delma.caiati@guggenheimpartners.com (1) Phase IIa PreciSION study (n~16) has recently completed patient enrollment, and

617 859 4606 the company has reiterated topline readout guidance for summer 2026 (we think

around mid-Aug/Sept timeframe; LPI occurred post-Trikafta run-in, before first pbo- Iris Gao, Ph.D.

iris.gao@guggenheimpartners.com randomization; See note HERE), with the goal of detecting ≥10 mmol/L SwCl

212 518 9013 improvement in F508del/F508del CF patients. Given the robust preclinical evidence

of NBD1 stabilization, we are optimistic that SION can accomplish this 10 mmol/L

efficacy (Importantly, Alyftrek has only achieved ~3 mmol/L SwCl improvement in

a similar target CF patient pool); and (2) Phase I dual combo study (n~24) in HVs is

SION BUY alsomappingongoing,exposureswith thebackgoalto oftheevaluatingCFHBE assaysafety,totolerability,predict CFTRand functionalPK, then subsequentlyrescue. Data

Sionna Therapeutics, Inc. readout is also on-track for summer 2026. These readouts could collectively de-risk the