Results following completion of phase I clinical trial using ex vivo expanded CD4+CD127lo/-CD25+ polyclonal tregs for the treatment of recent-onset type 1 diabetes

Study participants with recent-onset type 1 diabetes, between the ages of 18-45, have been successfully treated with ex vivo expanded polyclonal Tregs in a JDRF-sponsored phase I clinical trial. In this clinical trial, we were able to generate therapeutically relevant numbers of sufficiently pure polyclonal CD4+CD127lo/-CD25+ Tregs for clinical use using a flow based isolation procedure. Following the completion of the trial, 14 study participants were treated with either 5x10e6, 40x10e6, 320 x10e6 or 2.6 x10e9 Tregs following an ex vivo expansion using anti-CD3/anti-CD28-coated beads plus IL-2. Cells expanded on average of 650.2 fold (range 29.8-1366.8) and expressed 76-96.9% FOXP3+ (mean 92.2%) following the 14 day expansion period. In addition, these CD4+CD127lo/-CD25+ Tregs exhibit potent suppressor activity, and maintain high CD4 (mean 97.4%; range 95-98.7%) and CD25 expression and low CD127 and CD8 (mean 0.6%; range 0.1-2.4%) expression following the clinical expansions. All anti-CD3/anti-CD28-coated beads were removed from the expansion cultures prior to infusion based on specifications approved by the FDA. Additionally, all sterility release criteria with regard to anaerobic/aerobic bacterial testing, mycoplasma, endotoxin, gram stain, KOH and fungal cultures were negative. All Tregs were manufactured at UCSF and freshly infused at either Yale University or UCSF illustrating feasibility of transport and stability overnight. This is the first study where Tregs have been cultured in the presence of deuterated glucose [D-GLUCOSE (6,6-D2, 99%)] and are able to be tracked in vivo following infusion into study participants. The tracking results, as well as mechanistic data (flow cytometry, subset analysis, pSTAT5 and cytokine analysis), from the entire phase I clinical trial will be presented.