Vial Doses First Patient for Phase 1 Trial of Vial’s IL-13 x TSLP, a Novel Bispecific Antibody

• Vial’s IL13 x TSLP is a half-life-extended bispecific antibody engineered for projected quarterly-to-biannual dosing
• Preclinical data demonstrates picomolar binding affinities for both IL‑13 and TSLP, with near-complete inhibition of CCL17 secretion versus approved IL‑13 and TSLP monoclonal antibodies
• Phase 1 study will evaluate safety, tolerability, pharmacokinetics, pharmacodynamics, and proof‑of‑mechanism in healthy volunteers and patients with mild‑to‑moderate asthma
• Interim Phase 1 data readout expected in H1 2026

Vial, a clinical-stage biotechnology company, today announced that it has dosed the first patient in its Phase 1 clinical trial in Australia for Vial’s IL13 x TSLP. Vial’s IL13 x TSLP is a novel bispecific antibody in development for the treatment of mild‑to‑moderate asthma.

Vial’s IL13 x TSLP is engineered to achieve broad inhibition of Type 2 inflammation by simultaneously neutralizing IL‑13, a key effector cytokine, and the upstream alarmin TSLP. The program incorporates half‑life extension technology intended to enable convenient, infrequent dosing at projected quarterly‑to‑biannual intervals. In preclinical studies, Vial’s IL13 x TSLP demonstrated picomolar binding affinities for both targets and near‑complete inhibition of CCL17 secretion, a key pharmacodynamic marker of Type 2 pathway activation, compared with approved anti‑IL‑13 and anti‑TSLP monoclonal antibodies.

"Entering clinical stage is a pivotal milestone on our path to delivering Vial's IL13 x TSLP to people living with asthma," said Simon Burns, CEO at Vial. "Our goal is to deliver deeper, more durable control of Type 2 inflammation while substantially improving dosing convenience. We look forward to sharing clinical readouts as the program progresses."

The first‑in‑human Phase 1 trial will evaluate the safety, tolerability, pharmacokinetics, and pharmacodynamic markers of dual IL‑13 and TSLP inhibition in healthy adult volunteers and in patients with mild‑to‑moderate asthma, with exploratory endpoints relevant to establishing proof‑of‑mechanism. An interim data readout is expected later in H1 2026.

"We are pleased to lead this first‑in‑human trial of Vial’s IL13 x TSLP in healthy adults and patients with mild‑to‑moderate asthma," said Swati Khanna, Vice President of Research. "By targeting two key cytokines — IL‑13 and TSLP — this investigational therapy has the potential to address Type 2 inflammation through a differentiated mechanism, and we look forward to evaluating its clinical profile."

About Vial’s IL13xTSLP Phase 1 Study

The IL13 x TSLP Phase 1 study is a multi-site, open-label, first‑in‑human trial consisting of single ascending dose cohorts in healthy adult volunteers, followed by a randomized, placebo-controlled cohort expansion in participants with mild‑to‑moderate asthma. Primary endpoints include safety, tolerability, pharmacokinetics, and pharmacodynamic biomarkers of dual pathway inhibition. Data from this study are expected to inform dose selection and trial design for future development in asthma and other atopic or inflammatory diseases.

About Vial's IL‑13xTSLP Bispecific Antibody Program

Vial’s IL13 x TSLP is a novel bispecific antibody targeting IL‑13 and TSLP to address both the initiation and effector arms of Type 2 inflammation. Preclinical data support a potentially best‑in‑class profile characterized by picomolar dual-target binding, robust pathway inhibition, and favorable developability characteristics supporting an extended dosing interval. The program is initially being developed for mild‑to‑moderate asthma, with potential for indication expansion into other atopic and inflammatory diseases.

 Forward-Looking Statements

This press release contains forward-looking statements within the meaning of applicable securities laws. These statements include, but are not limited to, statements regarding: the anticipated initiation and timing of clinical trials; the therapeutic potential of Vial’s IL13xTSLP program; expected data readout timelines; projected dosing intervals; and plans for future clinical development. These statements involve risks and uncertainties, and actual results may differ materially from those expressed or implied. Factors that could cause differences include: unexpected safety or efficacy results observed during clinical studies; changes in regulatory requirements; the ability to enroll patients on the expected timeline; and general clinical development risks. Vial undertakes no obligation to update forward-looking statements to reflect events or circumstances arising after the date of this release, except as required by law.