The effects of low-dose IL-2 on Treg adoptive cell therapy in patients with Type 1 diabetes.

Background A previous Phase I study showed that the infusion of autologous Treg cells expanded ex-vivo into recent onset Type 1 Diabetes (T1D) patients had an excellent safety profile, however, the majority of the infused Tregs could no longer be detected in the peripheral blood three months post-infusion (NCT01210664-Treg-T1D Trial). Interleukin-2 (IL-2) has been shown to enhance human Treg cell survival and expansion at low doses in vivo. Therefore, we conducted a Phase 1 study (NCT02772679-TILT trial) combining polyclonal Treg and low-dose IL-2 and assessed the impact over time on Tregs populations and other immune cells. Methods T1D Patients were treated with a single infusion of autologous polyclonal Tregs, expanded ex vivo, followed by one or two 5-day courses of recombinant human low dose IL-2 (ld-IL-2) at 0.3 x 106 to 1 x 106 units/dose. Fluorescence-based flow cytometry, Cytometry by Time Of Flight (CyTOF) and 10X Genomics single cell RNAseq were used to follow the distinct immune cell populations phenotypes over time following immunotherapy. Results Multiparametric analysis revealed that the combination therapy led to an increase in the number of infused and endogenous Tregs but also resulted in a significant increase from baseline in a subset of activated NK, Mucosal-Associated Invariant T (MAIT) cells and clonal CD8+ T populations. Conclusions These data support the hypothesis that Id-IL-2 expands exogenously administered Tregs but also can expand cytotoxic cells. These results have important implications for the use of a combination of ld-IL-2 and Tregs for the treatment of autoimmune diseases with pre-existing active immunity. Trial registration ClinicalTrials.gov NCT01210664 (Treg-T1D Trial), NCT02772679 (TILTtrial). Funding Sean N. Parker Autoimmunity Research Laboratory Fund, National Center for Research Resources.