SION - Weekend Reading - Revisiting Our Scenario Analysis for Upcoming preciSION Readout in August

Research evidence excerpt

SION - Weekend Reading - Revisiting Our Scenario Analysis for Upcoming preciSION Readout in August

July 24, 2026

Yatin Suneja yatin.suneja@guggenheimpartners.com SION - Weekend Reading - Revisiting Our Scenario

212 518 9565 Analysis for Upcoming preciSION Readout in August

Min Lee, Ph.D.

min.lee@guggenheimpartners.com

212 823 6744 Key Message: Ahead of the upcoming Phase II preciSION readout in the next 2-4

weeks, we wanted to compile a handful of questions from the buy-side in regards to the Eddie Hickman, Ph.D.

eddie.hickman@guggenheimpartners.com study design, expectations, and the potential stock reaction. Please refer to our recent

212 518 9904 deep dive (SION - Previewing preciSION Study - Is NBD1 Stabilization Truly a Birth of

a New Paradigm or Just Another Mirage in the Cystic Fibrosis Treatment Landscape?) Delma Caiati, M.D., Ph.D. for our detailed analysis. Consistent with mgmt guidance and remarks from KOLs and delma.caiati@guggenheimpartners.com

617 859 4606 CF Foundation, we think ~10 mmol/L improvement in SwCl is a highly competitive

outcome that would not only validate the NBD1 biology and the company's CFHBE assay

Iris Gao, Ph.D. but would also imply there is plenty of room for improvement for Trikafta-controlled CF iris.gao@guggenheimpartners.com

patients. We reiterate our BUY rating, PT remains $50. Happy Friday! 212 518 9013

Most Common Questions From the Buy-side

1. Bar for success for SwCl? Mgmt continues to anchor towards 10 mmol/L figure,

but what is the acceptable range?Above 10 mmol/L would be a clear success SION BUY that validates NBD1 biology and synergistic potential with Trikafta. 8 mmol/L would Sionna Therapeutics, Inc. still represent best-in-disease SwCl improvement in homozygous CF patients already Sector: Biotechnology