Mozart Therapeutics Announces Positive Interim Phase 1 Data in Adults with Stage 3 Type I Diabetes

MTX-101 demonstrated decreases in self-reactive pathogenic T cells, improved β cell viability, and—at higher dose levels—numeric increase of C-peptide production

SEATTLE and BRISBANE, Australia, April 23, 2026 /PRNewswire/ -- Mozart Therapeutics, the leading developer of CD8 Treg network modulators for the treatment of autoimmune disease, today announced the release of interim Phase 1b (Ph1b) patient data for their lead program, MTX-101, in development for the treatment of type 1 diabetes (T1D). In a series of presentations at the 21st Immunology of Diabetes Society (IDS) Congress—April 20‒24; Brisbane, Australia—the Company provided a comprehensive update on the MTX-101 program, including results from the completed Ph1a study in healthy adults, pre-clinical description of the CD8 Treg network in adolescents with T1D, and Ph1b proof-of-mechanism data in adults with T1D. The program update culminated with an invited oral presentation which revealed new data from the ongoing Ph1b study in adults with T1D (NCT06324604).

Oral Presentation Highlights:
Interim data were presented on n=5 adults with Stage 3 T1D. The Ph1b study randomized participants to receive MTX-101 administered at 0.05 mg/kg (n=2) or 0.15 mg/kg (n=3). All 5 patients showed selective activation and proliferation of CD8 Treg, a reduction in the prevalence of pathogenic CD4 and CD8 T cells in peripheral blood, and reduced responses to autoantigen restimulation—collectively demonstrating proof-of-mechanism. T1D is characterized by a marked and highly-predictable decline in C-peptide, an indicator of β cell function and insulin release, over time. In contrast, the Ph1b study participants who received a single dose of MTX-101 at the higher dose level maintained or increased C-peptide values compared to baseline through end-of-study (EOS; approximately 20 weeks). For reference, in a meta-analysis of 21 clinical studies in patients with newly-diagnosed T1D, the 246 patients receiving placebo experienced declines in C-peptide of ~17% at 12 weeks and ~37% at 26 weeks.

The 5 participants ranged in age from 30‒39 years, were 6‒252 months (median: 36 months) from initial T1D diagnosis, and all presented with at least 1 T1D autoantibody at study entry; n=3 had ≥1 comorbid autoimmune diagnoses. Participants were required to have C-peptide ≥0.2nmol/L at screening. Treatment-emergent adverse events were mostly transient and generally mild or moderate in severity or consistent with other immunomodulatory therapies.

Collectively, these data illustrate for the first time the effects of selective modulation of the CD8 Treg network in patients and support the development of MTX-101 as a novel targeted approach to restoring immune homeostasis in patients with Stage 3 T1D.

"The rich nature of this interim analysis unveils key insights into how restoring CD8 Treg function might translate into disease-modifying clinical benefit for T1D. I am really looking forward to the MTX-101 Phase 2 study next year," said Professor John Wentworth, M.D.; Endocrinologist, The Royal Melbourne Hospital Department of Diabetes and Endocrinology; Senior Clinical Research Fellow, St Vincent's Institute of Medical Research; Director, ANZ Type 1 Diabetes TrialNet. "We want to express our deepest gratitude for all the patients and the staff at the clinical sites, all of whom are absolutely critical for advancing novel therapeutics for treating Stage 3 T1D."

"We are excited about the encouraging dataset from the Ph1b interim analysis demonstrating MTX–101 selectively modulates a novel regulatory pathway that translates into a meaningful impact on a key clinical biomarker, offering promise for patients with Stage 3 T1D," said Katie Fanning, President and CEO of Mozart Therapeutics. "These findings support our plans to complete the Ph1b study and initiate enrollment in a global Phase 2 study early in 2027."

Posters can be accessed from the Mozart Therapeutics website.

About MTX-101
MTX-101 is an antigen-agnostic bispecific antibody targeting inhibitory KIR and CD8 expressed on regulatory CD8 T cells. This autoimmune checkpoint inhibitor aims to restore the intrinsic functions of CD8 Treg, acting early in the autoimmune disease process to suppress and eliminate pathogenic T cells, halt downstream inflammation, and prevent tissue destruction.

About Mozart Therapeutics
Mozart Therapeutics and Mozart Therapeutics Australia, Pty LTD are focused on developing first-in-class disease-modifying therapies for autoimmune and inflammatory diseases, utilizing a novel approach to restoring immune system homeostasis by targeting the CD8 Treg network. The company global headquarters is in Seattle, WA, with a subsidiary in Brisbane, QLD, that is responsible for the ongoing Phase 1 study in Australia. For more information, visit www.mozart-tx.com and follow the company on LinkedIn @Mozart-tx.

SOURCE Mozart Therapeutics