A Study to Assess the Safety and Tolerability of Different Doses of AG019 Administered Alone or in Combination With Teplizumab in Participants With Recent-onset Diagnosed Type 1 Diabetes (T1D)

The purpose of this study is to assess the safety and tolerability of different doses of AG019 administered alone or in combination with teplizumab in participants with recent-onset type 1 diabetes (T1D).

This Phase 1b/2a, multi-center study will be conducted in participants with clinical recent-onset type 1 diabetes (T1D). The primary objective of this study is to assess the safety and tolerability of different doses of AG019 alone as well as AG019 in combination with teplizumab. The secondary objectives of this study are: to obtain pharmacodynamic (PD) data of AG019 alone as well as AG019 in combination with teplizumab; and to determine the potential presence of AG019 in systemic circulation (safety - systemic exposure) and the presence of L. lactis bacteria in fecal excretion (local exposure): Pharmacokinetic (PK) profile. This study consists of 2 phases: Phase 1b: this open-label part of the study will investigate the safety and tolerability of 2 different doses of AG019 in 2 age groups (18-40 years of age and 12-17 years of age). Phase 2a: this randomized, double-blind part of the study will investigate the safety and tolerability of AG019, in combination with teplizumab, in 2 age groups (18-40 years of age and 12-17 years of age).