A first-in-human, open-label Phase 1b and a randomised, double-blind Phase 2a clinical trial in recent-onset type 1 diabetes with AG019 as monotherapy and in combination with teplizumab

Abstract

Aims/hypothesis: We hypothesised that islet beta cell antigen presentation in the gut along with a tolerising cytokine would lead to antigen-specific tolerance in type 1 diabetes. We evaluated this in a parallel open-label Phase 1b study using oral AG019, food-grade Lactococcus lactis bacteria genetically modified to express human proinsulin and human IL-10, as a monotherapy and in a parallel, randomised, double-blind Phase 2a study using AG019 in combination with teplizumab.

Methods: Adults (18-42 years) and adolescents (12-17 years) with type 1 diabetes diagnosed within 150 days were enrolled, with documented evidence of at least one autoantibody and a stimulated peak C-peptide level >0.2 nmol/l. Participants were allocated to interventions using interactive response technology. We treated 42 people aged 12-42 years with recent-onset type 1 diabetes, 24 with Phase 1b monotherapy (open-label) and 18 with Phase 2a combination therapy. In the Phase 2a study, after treatment of the first two open-label participants, all people involved were blinded to group assignment, except for the Data Safety Monitoring Board members and the unblinded statistician. The primary endpoint was safety and tolerability based on the incidence of treatment-emergent adverse events, collected up to 6 months post treatment initiation. The secondary endpoints were pharmacokinetics, based on AG019 detection in blood and faeces, and pharmacodynamic activity. Metabolic and immune endpoints included stimulated C-peptide levels during a mixed meal tolerance test, HbA_1c levels, insulin use, and antigen-specific CD4⁺ and CD8⁺ T cell responses using an activation-induced marker assay and pooled tetramers, respectively.

Results: Data from 24 Phase 1b participants and 18 Phase 2a participants were analysed. No serious adverse events were reported and none of the participants discontinued AG019 due to treatment-emergent adverse events. No systemic exposure to AG019 bacteria, proinsulin or human IL-10 was demonstrated. In AG019 monotherapy-treated adults, metabolic variables were stabilised up to 6 months (C-peptide, insulin use) or 12 months (HbA_1c) post treatment initiation. In participants treated with AG019/teplizumab combination therapy, all measured metabolic variables stabilised or improved up to 12 months and CD8⁺ T cells with a partially exhausted phenotype were significantly increased at 6 months. Circulating preproinsulin-specific CD4⁺ and CD8⁺ T cells were detected before and after treatment, with a reduction in the frequency of preproinsulin-specific CD8⁺ T cells after treatment with monotherapy or combination therapy.

Conclusions/interpretation: Oral delivery of AG019 was well tolerated and safe as monotherapy and in combination with teplizumab. AG019 was not shown to interfere with the safety profile of teplizumab and may have additional biological effects, including changes in preproinsulin-specific T cells. These preliminary data support continuing studies with this agent alone and in combination with teplizumab or other systemic immunotherapies in type 1 diabetes.

Trial registration: ClinicalTrials.gov NCT03751007, EudraCT 2017-002871-24 FUNDING: This study was funded by Precigen ActoBio.

Keywords: AG019; Anti-CD3 monoclonal antibody; Antigen-specific immunotherapy; IL-10; Lactococcus lactis bacteria; Oral tolerance; Proinsulin; Teplizumab; Type 1 diabetes.

Fig. 1

Participant disposition. ^aA total of three single-dose participants were re-enrolled as repeat-dose participants in the different monotherapy cohorts. ^bSingle-dose participants were not included in the ITT and PP analysis sets. FU, follow-up; PD, protocol deviation; RD, repeat dose; SAF, safety analysis set; SD, single dose

Fig. 2

Concentrations of AG019 bacteria in faecal samples collected after the last day of AG019 dosing (day 56) from participants treated with (a) AG019 monotherapy or (b) AG019/teplizumab combination therapy. LLeq, L. lactis equivalents; grey area is below the limit of detection (LOD) (i.e. 9×10³ LLeq/g). Bacterial concentrations are expressed as LLeq/g and were log-transformed. Bars indicate means ± SEM. Faecal samples from 25 participants were analysed: nine AG019 monotherapy participants (five adults, four adolescents, all high-dose treated), 13 AG019/teplizumab combination therapy participants (ten adults, three adolescents) and three placebo participants (all negative; data not shown). Participants excluded from the PP analysis set are indicated in open symbols

Fig. 3

C-peptide mean 2 h AUC over time. (a) Absolute values in participants treated with AG019 monotherapy. (b) Percentage change from baseline in participants treated with AG019 monotherapy. (c) Absolute values in participants treated with AG019/teplizumab combination therapy and placebo. (d) Percentage change from baseline in participants treated with AG019/teplizumab combination therapy and placebo. Data are based on the PP analysis set and are means ± SEM. Pairwise comparison vs baseline (post hoc t test): *p<0.05 (in adolescents), **p<0.01 (in adolescents), ^†p<0.05 (in adults). Grey shading indicates the AG019 treatment period; blue shading indicates the AG019+teplizumab treatment period

Fig. 4

HbA_1c (a, c) and insulin use (b, d) over time in participants treated with (a, b) AG019 monotherapy or (c, d) AG019/teplizumab combination therapy and placebo. Data are based on the PP analysis set. Horizontal line for HbA_1c represents the target for glycaemic control (53 mmol/mol). Pairwise comparison vs baseline (post hoc t test): *p<0.05, **p<0.01 in adults. Data are means ± SEM. Grey shading indicates the AG019 treatment period; blue shading indicates the AG019+teplizumab treatment period

Fig. 5

Frequency of partially exhausted (EOMES⁺TIGIT⁺) CD8⁺ T cells over time in participants treated with AG019 monotherapy, AG019/teplizumab combination therapy and placebo. (a) Data per treatment group. (b) Individual data. Data are based on a subset of the PP analysis set; adults and adolescents are included together. Percentages were normalised to baseline using the log fold change and data are means ± SEM. Mixed effect analysis vs baseline: ^†p<0.05; unpaired t test vs AG019: **p<0.01. Blue lines, monotherapy; red lines, combination therapy; black lines, placebo. Grey shading indicates the AG019 treatment period; blue shading indicates the AG019+teplizumab treatment period

Fig. 6

Frequency of (a) PPI-specific CD8⁺ T cells and (b) CMV/EBV-specific CD8⁺ T cells over time in participants treated with AG019 monotherapy and AG019/teplizumab combination therapy. Data are based on the PP analysis set. Percentages were normalised to baseline using the log fold change and data are means ± SEM. Mixed effect analysis vs baseline: *p<0.05 (AG019 monotherapy), ^†p<0.05 (AG019/teplizumab combination therapy). Grey shading indicates the AG019 treatment period; blue shading indicates the AG019+teplizumab treatment period. CMV/EBV, cytomegalovirus/Epstein–Barr virus

Fig. 7

Frequency of PPI-specific (a) Tr1s and (b) memory Tregs (mTregs) in adults treated with AG019 monotherapy or AG019/teplizumab combination therapy. (a) The frequency of PPI-specific IL-10⁺ Tr1s in adults treated with AG019 monotherapy (n=3) or AG019/teplizumab combination therapy (n=5) at baseline and at month 3. Thick lines represent the mean frequency and thin lines depict the frequency of cells for each participant. (b) The frequency of PPI-specific mTregs in adults treated with monotherapy (n=4) or combination therapy (n=7) at baseline, 3 months and 6 months as described in (a). Two adult participants treated with placebo are depicted in black. The parent population for Tr1s and mTregs is total PPI-specific CD4⁺ T cells. Grey shading indicates the AG019 treatment period; blue shading indicates the AG019+teplizumab treatment period

Fig. 8

PPI-specific CD8⁺ T cells over time in clinical responders and non-responders at 6 months in (a) AG019 monotherapy and (b) AG019/teplizumab combination therapy. Data are based on a subset of the PP analysis set and are presented as means ± SEM. AG019 monotherapy responders (n=3, blue); AG019 monotherapy non-responders (n=4, grey); AG019/teplizumab combination therapy responders (n=11, red); AG019/teplizumab combination therapy non-responders (n=2, grey). Grey shading indicates the AG019 treatment period; blue shading indicates the AG019+teplizumab treatment period