OPT101 Phase 1b in adults with type 1 diabetes
A completed, placebo-controlled Phase 1b study of the CD154-derived peptide OPT101 in 24 adults with T1D. Results posted 10 August 2026 show a small safety dataset and no C-peptide advantage over placebo.
Primary endpoints
- Number of treatment-related adverse events (CTCAE v4.0) over 42 days
Results so far
Results posted 10 August 2026. 24 participants started (8 per arm); 18 completed. One treatment-related adverse event in each OPT101 dose group and none on placebo; no deaths. Posted end-of-study mixed-meal C-peptide means were 0.03 ng/mL (1.1 mg/kg), 0.07 ng/mL (2.8 mg/kg) and 0.16 ng/mL (placebo). That is not a C-peptide preservation signal. HbA1c change (mmol/mol) was also not better on drug. Do not treat completion, or the conference Th40 immunophenotyping abstract, as efficacy.
The full picture
This Phase 1b study asked whether repeated infusions of OPT101 are tolerable in adults with T1D and whether any early metabolic signal appears. The registry now has posted results. Safety looks acceptable in a tiny sample. The posted C-peptide and glucose tables do not support a claim that OPT101 preserves beta cells.