A phase II randomized trial with autologous polyclonal expanded regulatory T cells in children with new onset type 1 diabetes

CD4+CD25hiCD127lo/-FOXP3+ regulatory T cells (Tregs) play a key role in preventing autoimmunity. In autoimmune type 1 diabetes (T1D), adoptive transfer of autologous polyclonal Tregs has been shown to be safe in adults in Phase I clinical trials. We explored factors contributing to efficacy of autologous polyclonal expanded Tregs (expTregs) in a randomized Phase II multi-center, double-blind, clinical trial in 110 treated children and adolescents with new-onset T1D (Sanford/Lisata Therapeutics T-Rex Phase II trial) randomized 1:1:1 to high- (24*10^6 cells/kg) or low- (1*10^6 cells/kg) dose treatments or to matching placebo. Cytometry, bulk and single-cell RNA-sequencing were performed on selected expTregs and peripheral blood samples from participants. The single doses of expTregs were safe but did not prevent the decline in residual beta cell function over one year compared to placebo (P = 0.94 low dose, P = 0.21 high dose), regardless of age or baseline C-peptide. ExpTregs were highly activated and suppressive in vitro. A transient increase of activated memory Tregs was detectable one week after infusion in the high dose cohort suggesting effective transfer of expTregs. However, in vitro fold expansion of expTregs varied across participants even when accounting for age and lower fold expansion and its associated gene signature were linked with better C-peptide preservation regardless of Treg dose. These results suggest that a single dose of polyclonal expTregs does not alter progression in T1D; instead, Treg quality may be an important factor.

CD4+CD25hiCD127lo/-FOXP3+调节性T细胞（regulatory T cells，Tregs）在预防自身免疫疾病中发挥关键作用。在自身免疫性1型糖尿病（type 1 diabetes，T1D）中，成人自体多克隆Tregs过继转移疗法已在I期临床试验中被证实安全性良好。本研究针对110例新发T1D儿童及青少年受试者，开展了一项随机、多中心、双盲II期临床试验（Sanford/Lisata Therapeutics T-Rex II期临床试验），以1:1:1的比例将受试者随机分配至高剂量组（24×10^6细胞/千克）、低剂量组（1×10^6细胞/千克）及匹配安慰剂组，旨在探究影响自体多克隆扩增Tregs（expanded Tregs，expTregs）疗效的相关因素。研究人员对筛选获得的expTregs及受试者外周血样本开展了流式细胞术、批量RNA测序与单细胞RNA测序分析。结果显示，单次输注expTregs安全性良好，但与安慰剂组相比，未能在一年内延缓残余β细胞功能的衰退（低剂量组P=0.94，高剂量组P=0.21），且该结果不受受试者年龄或基线C肽水平的影响。expTregs在体外呈现高度活化状态且具备较强的抑制功能。高剂量组受试者在输注后一周可检测到活化记忆性Tregs的一过性升高，提示expTregs成功完成了体内转输。然而，即便校正年龄因素后，不同受试者的expTregs体外扩增倍数仍存在显著差异；且无论Tregs输注剂量如何，较低的扩增倍数及其相关基因特征均与更好的C肽保留水平相关。上述结果表明，单次输注多克隆expTregs无法改变T1D的疾病进展；相较而言，Tregs的质量或为影响疗效的关键因素。