Alefacept provides sustained clinical and immunological effects in new-onset type 1 diabetes patients

Abstract

Background: Type 1 diabetes (T1D) results from destruction of pancreatic β cells by autoreactive effector T cells. We hypothesized that the immunomodulatory drug alefacept would result in targeted quantitative and qualitative changes in effector T cells and prolonged preservation of endogenous insulin secretion by the remaining β cells in patients with newly diagnosed T1D.

Methods: In a multicenter, randomized, double-blind, placebo-controlled trial, we compared alefacept (two 12-week courses of 15 mg/wk i.m., separated by a 12-week pause) with placebo in patients with recent onset of T1D. Endpoints were assessed at 24 months and included meal-stimulated C-peptide AUC, insulin use, hypoglycemic events, and immunologic responses.

Results: A total of 49 patients were enrolled. At 24 months, or 15 months after the last dose of alefacept, both the 4-hour and the 2-hour C-peptide AUCs were significantly greater in the treatment group than in the control group (P = 0.002 and 0.015, respectively). Exogenous insulin requirements were lower (P = 0.002) and rates of major hypoglycemic events were about 50% reduced (P < 0.001) in the alefacept group compared with placebo at 24 months. There was no apparent between-group difference in glycemic control or adverse events. Alefacept treatment depleted CD4+ and CD8+ central memory T cells (Tcm) and effector memory T cells (Tem) (P < 0.01), preserved Tregs, increased the ratios of Treg to Tem and Tcm (P < 0.01), and increased the percentage of PD-1+CD4+ Tem and Tcm (P < 0.01).

Conclusions: In patients with newly diagnosed T1D, two 12-week courses of alefacept preserved C-peptide secretion, reduced insulin use and hypoglycemic events, and induced favorable immunologic profiles at 24 months, well over 1 year after cessation of therapy.

Trial registration: https://clinicaltrials.gov/ NCT00965458.

Funding: NIH and Astellas.

Figure 9. Baseline CD2 expression and changes in proportions (% of parent) of PD-1–expressing T cells (memory and Treg) from baseline to 24 months in participants assigned to alefacept and placebo.

(A and B) PD-1–expressing CD4⁺ and CD8⁺ Tem cells. (C) PD-1–expressing CD4⁺ Tregs. (D) CD2 expression (mean fluorescence intensity, MFI) at baseline in CD4⁺ memory T cells. Flow populations and analyses are as described in Figures 5 and 6. Data are mean values ± SD. *P < 0.01. For all analyses, the number of evaluable subjects (n) at each time point is shown in Figure 1. C1 and C2 denote the two 12-week treatment courses. For additional details, see https://www.itntrialshare.org/T1DAL_fig9.url.

Figure 8. Changes in proportions (% of parent) of PD-1–expressing T cells (naive and central memory) from baseline to 24 months in participants assigned to alefacept and placebo.

(A and B) PD-1–expressing CD4⁺ and CD8⁺ Tn cells. (C and D) PD-1–expressing CD4⁺ and CD8⁺ Tcm. Flow populations and analyses are as described in Figures 5 and 6. Data are mean values ± SD. *P < 0.01. For all analyses, the number of evaluable subjects (n) at each time point is shown in Figure 1. C1 and C2 denote the two 12-week treatment courses. For additional details, see https://www.itntrialshare.org/T1DAL_fig8.url.

Figure 7. Changes in ratios of Tregs to memory T cells from baseline to 24 months in participants assigned to alefacept and placebo.

(A and B) Ratios of Tregs to CD4⁺ and CD8⁺ Tcm. (C and D) Ratios of Treg to CD4⁺ and CD8⁺ Tem cells. Flow populations and analyses are as described in Figures 5 and 6. Data are mean values ± SD presented as % change from baseline. *P < 0.01. For all analyses, the number of evaluable subjects (n) at each time point is shown in Figure 1. C1 and C2 denote the two 12-week treatment courses. For additional details, see https://www.itntrialshare.org/T1DAL_fig7.url.

Figure 6. Changes in lymphocyte populations from baseline to 24 months in participants assigned to alefacept and placebo.

(A) CD4⁺ Tcm (CD4⁺ CD127⁺ FoxP3^– CD45RA^– CD45RO⁺ CCR7⁺). (B) CD8⁺ Tcm (CD8⁺ CD45RA^– CD45RO⁺ CCR7⁺). (C) CD4⁺ Tem (CD4⁺ CD127⁺ FoxP3^– CD45RA^– CD45RO⁺ CCR7^–). (D) CD8⁺ Tem (CD8⁺ CD45RA^– CD45RO⁺ CCR7^–). Data were analyzed as described in Figure 5 and are mean values ± SD. Percent change from baseline is presented for T cell subsets as % of CD4⁺ non-Treg or CD8⁺ T cells in B–D. *P < 0.01. For all analyses, the number of evaluable subjects (n) at each time point is shown in Figure 1. C1 and C2 denote the two 12-week treatment courses. For additional details, see https://www.itntrialshare.org/T1DAL_fig6.url.

Figure 5. Baseline CD2 expression and changes in lymphocyte populations from baseline to 24 months in participants assigned to alefacept and placebo.

(A) CD2 expression (mean fluorescence intensity, MFI) at baseline on studied T cell subpopulations. (B) CD4⁺ Tn cells (CD4⁺ CD127⁺ FoxP3^– CD45RA⁺ CD45RO^– CCR7⁺). (C) CD8⁺ Tn cells (CD8⁺ CD45RA⁺ CD45RO^– CCR7⁺). (D) CD4⁺ Tregs (CD4⁺ CD127^–/lo FoxP3⁺). Flow cytometry data were log-transformed and analyzed by repeated measures ANOVA, and P values were calculated to compare the differences of least square means between treatment groups at every visit. Data are mean values ± SD. Percent change from baseline is presented for T cell subsets as % of CD4⁺ non-Treg or CD8⁺ T cells in B–D. *P < 0.01. For all analyses, the number of evaluable subjects (n) at each time point is shown in Figure 1. C1 and C2 denote the two 12-week treatment courses. For additional details, see https://www.itntrialshare.org/T1DAL_fig5.url.

Figure 3. Responder analysis based on thresholds of preservation of baseline C-peptide secretion at 2 years.

The % change in 4-hour C-peptide AUC from baseline to 2 years was plotted for each subject as a function of age (blue, younger subjects; red, older subjects); top, alefacept arm; bottom, placebo arm. Subjects to the right of the dotted line (>0% change) are denoted complete responders; subjects to the right of the broken line (<50% decrease from baseline) are partial responders. In the alefacept arm, subjects to the left of the solid line (>40% decrease) are classified as worst responders (n = 9) for comparison with complete responders (n = 9). For additional details, see https://www.itntrialshare.org/T1DAL_fig3.url.

Figure 1. CONSORT diagram showing allocation and disposition of study subjects in the T1DAL trial.

Figure 4. Changes in lymphocyte absolute cell counts from baseline to 24 months.

(A) Total CD4⁺ T cells. (B) Total CD8⁺ T cells. Data are mean values ± 95% CI. For all analyses, the number of evaluable subjects (N) at each time point is shown in Figure 1. For additional details, see https://www.itntrialshare.org/T1DAL_fig4.url.

Figure 2. Clinical responses from baseline to 24 months in participants assigned to alefacept and placebo in the ITT sample.

(A) Change in 4-hour C-peptide AUC. *P = 0.019, **P = 0.002. (B) Change in HbA1c. (C) Change in exogenous insulin requirements. *P = 0.020, **P = 0.002. Data were analyzed by fitting ANCOVA models with adjustment for baseline levels and plotted as unadjusted means ± 95% CI. P-values are 2-sided. (D) Rate of major hypoglycemic events. Event rates between the 2 groups were compared using Poisson regression. *P < 0.001. For all analyses, the number of evaluable subjects (n) at each time point is shown in Figure 1. C1 and C2 denote the two 12-week treatment courses. For additional details, see https://www.itntrialshare.org/T1DAL_fig2.url.