Treatment of type 1 diabetes with teplizumab: clinical and immunological follow-up after 7 years from diagnosis

Abstract

Aims/hypothesis: The long-term effects of successful immune therapies for treatment of type 1 diabetes have not been well studied. The Autoimmunity-Blocking Antibody for Tolerance (AbATE) trial evaluated teplizumab, an Fc receptor non-binding humanised anti-CD3 monoclonal antibody in individuals with new-onset type 1 diabetes, and ended in 2011. Clinical drug-treated responders showed an increased frequency of 'partially exhausted' CD8⁺ T cells. We studied the clinical, immunological and metabolic status of participants after an average follow-up of 7 years.

Methods: Participants with detectable C-peptide at year 2 of AbATE returned for follow-up. C-peptide responses were assessed by 4 h mixed-meal tolerance test. Autoantibodies and HbA_1c levels were measured and average daily insulin use was obtained from patient logs. Peripheral blood mononuclear cells were analysed by flow cytometry and cytokine release.

Results: Fifty-six per cent of the original participants returned. Three of the original control group who did not return had lost all detectable C-peptide by the end of the 2 year trial. The C-peptide responses to a mixed-meal tolerance test were similar overall in the drug vs control group of participants but were significantly improved, with less loss of C-peptide, in drug-treated responders identified at 1 year. However, the improvements in C-peptide response were not associated with lower HbA_1c levels or insulin use. Drug-treated responders showed a significantly increased frequency of programmed cell death protein 1-positive central memory and anergic CD8⁺ T cells at follow-up.

Conclusions/interpretation: These findings suggest there is reduced decline in C-peptide and persistent immunological responses up to 7 years after diagnosis of diabetes in individuals who respond to teplizumab.

Trial registration: ClinicalTrials.gov NCT02067923; the protocol is available at www.immunetolerance.org (ITN027AI).

Keywords: Anergy; Anti-CD3; C-peptide; Exhaustion; T cells; Teplizumab; Type 1 diabetes.

Fig. 1

C-peptide responses following an MMTT after mean follow-up of 7 years, (a) C-peptide response (log_e [(AUC/240)+l]) of the control (n=12) and drug-treated participants (n=31) at follow-up visit 1, presented as nmol/l. Each symbol represents a participant. For comparison, the values were adjusted for duration of diabetes (difference not statistically significant, mixed model). (b) The C-peptide response AUC was examined in drug-treated responders, drug-treated non-responders and control participants at follow-up visit 1. (c) The percentage of participants with detectable levels of C-peptide at follow-up was higher in the drug-treated responders (n=10) vs control participants (n=12) and drug-treated non-responders (n=21) (p=0.009, χ² test). (d) The decrease in C-peptide response AUC, as a percentage of the response at baseline, at the follow-up visit adjusted for the duration of diabetes. (e) The C-peptide response AUC did not decline significantly between follow-up visit 1 and follow-up visit 2 (mean 0.144±0.052 vs 0.120±0.043). White circles, non-responders (n=5); black circles, responders (n=7). All data are means ± SEM; *p<0.05, **p<0.01, ***p<0.001

Fig. 2

Metabolic responses to teplizumab treatment, (a) C-peptide response (log_e [(AUC/240)+1], in nmol/l), (b) daily insulin use and (c) HbA_1c levels during the AbATE trial period (in months) and at follow-up visit 1 (f/u V1) were compared in a mixed model. Means ± SEM from the mixed model are shown; *p<0.05, **p<0.01, ***p<0.001 for comparison of drug-treated responders vs drug-treated non-responders at each time point shown; ^†p<0.05, ††p<0.001, ††† p<0.001 for comparison of drug-treated responders and control participants at each time point shown

Fig. 3

Relationship between the baseline C-peptide and the C-peptide at follow-up. The baseline C-peptide and change in C-peptide are shown for the three groups (log_e[(AUC/240)+1], in nmol/l). There was a significant relationship between the baseline C-peptide and the change for the control participants (Spearman r=−0.704, p=0.005) and drug-treated non-responders (r=−0.836, p=0.002) but not the drug-treated responders (r=−0.297, p=0.41)

Fig. 4

CD8⁺ T cell subsets during the AbATE trial period (in months) and at follow-up visit 1 (f/u V1). (a) The frequency of PD-1⁺ CD8⁺ central memory (CM) T cells was compared between the groups at the f/u V1 (p=0.018, Kruskal–Wallis test, *p<0.05 for post hoc comparisons; n=11, 19 and 8 for control participants, drug-treated non-responders and drug-treated responders, respectively). The values represent the percentage of the total CD8⁺ T cells, (b-f) Cell subsets: (b) PD-1⁺CD8⁺ T cells, (c) exhausted CD8⁺ T cells, (d) anergic CD8⁺ T cells, (e) anergic CD4⁺ T cells and (f) CD4⁺ Tregs were compared between the three groups using a mixed model with repeated measures. There was an increased frequency of anergic CD8⁺ T cells (CD8⁺PD-1⁺KLRG1⁻CD57⁻) (d) at follow-up visit 1, but not anergic CD4⁺ T cells (e) or exhausted CD8⁺ T cells (CD8⁺PD-1⁺KLRG1⁺CD57⁻) (c) in the drug-treated responders vs drug-treated non-responders. We did not find a difference in the frequency of CD4⁺ Tregs between the groups except for a decline in the drug-treated responders vs drug-treated non-responders at 2 months (f). Means ± SEM from the mixed model are shown; for (b-f), n= 9–11 for controls, 8–19 for drug treated non-responders, 5–8 for drug treated responders; *p<0.05, **p<0,01, ***p<0.001 for comparison of drug-treated responders vs drug-treated non-responders at each time point shown

Fig. 5

Cytokine responses of T cell subsets. IFNG (a) and IL2 mRNA expression (b) after 24 h was measured in CD8⁺ effector memory and PD-1⁺CD8⁺ central memory T cells stimulated with PHA, or unstimulated (expressed as ΔC_t compared with actin). Data are means ± SEM; *p<0.05, **p<0,01, ***p<0.001, paired Student’s t test. For IFNG, n=6 for control and drug-treated responder groups and n=5 for drug-treated non-responder group; for IL2, due to very low expression of IL2 in some samples, n=4 for control group and n=4 for effector memory and n=5 for PD-1⁺CD8⁺ central memory T cells for the drug-treated responder and non-responder groups

Fig. 6

Predictive value of changes in T cell subsets at the end of the trial (at 2 years) and C-peptide responses at follow-up. A direct relationship was observed between (a) frequency of PD-1⁺CD8⁺ central memory (CM) T cells (Spearman’s r=0.46, p=0.019), (b) exhausted CD8⁺ T cells (Spearman’s r=0.51, p=0.009) and (c) anergic CD4⁺ T cells (Spearman’s r=0.53, p=0.006) at the end of the treatment period (year 2) and the C-peptide responses at the follow-up among all participants