YolTech Presented Proof-of-Concept Data from Clinical Trial of YOLT-202 in PiZZ Alpha-1 Antitrypsin Deficiency (AATD) Patients at European Respiratory Society Congress 2026

Single administration of YOLT-202 demonstrated increased AAT levels above the protective threshold and reaching lower limit of normal range; maintained durable AAT expression for six months following treatment

Corrected M-AAT accounted for up to 93.4% of circulating AAT in the 45mg cohort and up to 98.7% in the 35mg cohort

Well-tolerated safety profile across evaluated dose levels

SHANGHAI – September 7, 2026 - YolTech Therapeutics, a late clinical-stage biotechnology company pioneering in vivo gene-editing therapies, today announced that positive proof-of-concept data from the first-in-human investigator-initiated trial (IIT, NCT07193615) of YOLT-202 in patients with severe PiZZ alpha-1 antitrypsin deficiency (AATD) were presented in a Late Breaker presentation at the European Respiratory Society (ERS) Congress, taking place September 5-9, 2026, in Barcelona, Spain.

YOLT-202 is an in vivo gene-editing therapy that corrects PiZ mutation to PiM for the treatment of AATD.

Data from the four patients treated with a single-dose of YOLT-202 support a generally well-tolerated safety profile and demonstrate efficacy resulting in robust, dose-dependent increases in serum AAT levels, accompanied by reductions in circulating pathogenic Z-AAT protein. Increased AAT expression was sustained through up to six months of follow-up.

“Patients living with PiZZ AATD urgently need therapies that address the underlying genetic cause of disease rather than simply managing its symptoms,” said Simon Alexander Krooss, M.D., Ph.D., Hannover Medical School, Germany, and presenter of the Late Breaking data at ESR. “What makes these early YOLT-202 data particularly compelling is the convergence of multiple indicators of therapeutic activity following a single administration, including precise correction of the disease-causing mutation in the liver, substantial increases in functional AAT production, and reductions in pathogenic Z-AAT protein. The durability of expression observed through six months, together with a favorable safety profile and biopsy-confirmed editing, provides encouraging evidence that this approach has the potential to alter the course of disease and meaningfully improve outcomes for patients with AATD.”

YOLT-202 ERS Data

YOLT-202 is being evaluated in a Phase I open-label, single-dose escalation trial evaluating its safety and pharmacodynamic activity in AATD patients. Previously reported early data showed dose-dependent serum alpha-1-antitrypsin (AAT) increases above the protective threshold of 11 μM, with the 45mg dose achieving normal levels (>20 μM) and corrected M-AAT exceeding 95%, along with a favorable safety profile.

Based on the data presented, four patients have been treated across the 35mg (n=1) and 45mg (n=3) dose cohorts and followed for up to six months. Data from the 55mg dose cohort are pending.

Key data from the four evaluable patients include:

·        A single 45mg dose increased mean total AAT levels from approximately 5 μM at baseline to ~20 μM by Week 4, exceeding the 11 μM protective threshold and reaching the lower limit of normal range by Month 5, with levels maintained above the protective threshold through Month 6.

·        A single 35mg dose increased AAT levels from approximately 5 μM at baseline to ~11 μM by Week 2 and ~15 μM by Month 2, with levels maintained above the protective threshold through Month 6.

·        Dose-dependent increases in circulating AAT were observed across the 35mg and 45mg cohorts.

·        Corrected M-AAT comprised 93.4% of circulating AAT at Week 3 in patients receiving 45mg of YOLT-202. Corrected M-AAT comprised 98.7% of circulating AAT at Week 3 in the patient receiving 35mg of YOLT-202.

·        Liver biopsy analysis (not part of the study protocol) demonstrated up to 57% target-site editing efficiency, with no detectable bystander edits or off-target editing events.

·        Transient ALT elevations peaked at approximately 60-75 U/L and returned toward or below the upper limits of normal range by Day 21. Transient AST elevations peaked at approximately 45-55 U/L and trended toward normal range by Day 21. Bilirubin remained normal throughout follow-up.

“These data represent an important clinical validation of both YOLT-202 and the broader promise of in vivo base editing,” said Yuxuan Wu, Ph.D., Co-Founder and Chief Executive Officer of YolTech Therapeutics. “In just four patients treated to date, we have observed durable, dose-dependent increases in AAT levels above the protective threshold, substantial reductions in disease-causing Z-AAT protein, and direct correction of the target mutation at the source of disease following a single treatment. We believe these findings provide compelling proof-of-concept for our platform and reinforce the potential of YOLT-202 to become a first-in-class, one-time therapy capable of addressing both the liver and lung manifestations of AATD.”

About YOLT-202

YOLT-202 is an in vivo gene-editing therapy that corrects PiZ mutation to PiM for the treatment of AATD. Utilizing YolTech’s proprietary adenine base editor, YOLT-202 is engineered to achieve on-target editing with minimal bystander activity. The U.S. Food and Drug Administration (FDA) has granted Regenerative Medicine Advanced Therapy (RMAT) and Orphan Drug designations to YOLT-202 for the treatment of AATD.

About PiZZ (AATD)

PiZZ AATD is a severe, progressive genetic disease stemming from PiZ mutations in the SERPINA1 gene, which cause AAT proteins to misfold and accumulate in the liver and drastically reduce functional circulating AAT, leading to irreversible emphysema and liver complications such as fibrosis and cirrhosis. Largely underdiagnosed, this condition is currently managed with lifelong recurring plasma AAT infusions that merely relieve symptoms without correcting the genetic root, creating an urgent unmet clinical need for curative therapies targeting the underlying disease driver.  The rapidly expanding global AATD treatment market further underscores the critical demand for innovative disease-modifying gene-editing therapeutics for affected patients.

About YolTech Therapeutics

YolTech Therapeutics is a clinical-stage biotechnology company pioneering next-generation in vivo gene editing medicines for patients with serious genetic, cardiometabolic and autoimmune diseases. The company has built a fully integrated platform that combines HEPDONE™, its proprietary gene editing technologies, with AI-enabled discovery capabilities and targeted lipid nanoparticle (LNP) delivery systems designed to enable precise, one-time treatments with the potential for lifelong benefit. YolTech is advancing a broad portfolio of wholly owned and partnered programs spanning rare genetic diseases, cardiovascular and metabolic disorders, and autoimmune diseases, with multiple assets in clinical development. Founded on the vision of redefining genetic medicine through precision in vivo editing, YolTech is committed to developing transformative therapies that address the underlying cause of disease and improve outcomes for patients worldwide. 

Contacts:

Investor Contact: investors@yoltx.com

Company Contact: info@yoltx.com