A preclinical and phase I clinical study of ex vivo-expanded amyloid beta-specific human regulatory T cells in Alzheimer's disease

Introduction: Despite advancements in adoptive regulatory T cell (Treg) therapy, its application in Alzheimer's disease (AD) remains constrained by challenges in ex vivo Treg selection and expansion with antigen specificity. Our previous findings demonstrated the bystander suppressive immunomodulatory mechanism of ex vivo expanded amyloid β-specific mouse Tregs in AD models, prompting inquiry into the efficacy of ex vivo expanded human Tregs in AD. Methods: We developed an effective ex vivo expansion method for manufacturing amyloid β-specific human Tregs (Aβ-hTreg) and evaluated their safety and efficacy in 3xTg mouse models of AD and a phase 1 clinical trial with six AD patients. The phenotype of Aβ-hTreg was analyzed using single-cell transcriptomics. The clinical trial involved intravenous administration of Aβ-hTreg, with three patients receiving a low dose and three receiving a high dose. Exploratory assessments of effectiveness, including cognitive tasks and functional evaluations, were conducted ninety days post-treatment. Results: Behavioral spatial learning and memory impairment, neuroinflammatory and amyloid pathology were dramatically ameliorated by single intrathecal administration of ex vivo expanded Aβ−hTreg to 3xTg AD mice. Single cell transcriptomics analysis revealed alterations in five key genes within a cluster of Tregs under antigen-specific manufacturing conditions. In the clinical trial with six AD patients, dose-limiting toxicity was experienced by none of the participants within five days of receiving GMP-grade Aβ-hTreg (VT301), indicating its good tolerability. Although exploratory assessments of effectiveness did not reach statistically significant values among the groups, these findings offer valuable insights for AD treatment and management, guiding the planning of the next phase of clinical trials. Discussion: This study suggests that hTregs may modulate Alzheimer's disease pathology by suppressing neuroinflammation, while VT301 shows promise as a safe treatment option. However, further research is necessary to confirm its clinical efficacy and optimize treatment strategies. Trial registration: Title: A Study of Possibility of Using Regulatory T Cells (VT301) for Treatment of Alzheimer's Disease, ClinicalTrials.gov NCT05016427, Study approval date: Ministry of Food and Drug Safety of the Republic of Korea (MFDS) - August 31st, 2020, Institutional Review Board (IRB) of Seoul National University Hospital, Republic of Korea - September 29th, 2020, The date of first patient enrollment: December 7th, 2020. https://clinicaltrials.gov/study/NCT05016427