The ProTreg21 Protocol: Phase I/IIa Regulatory T cell Therapy Clinical Trial in Deceased-Donor Kidney Transplantation

Long-term maintenance immunosuppression post kidney transplantation is associated with infection, malignancy, cardiovascular morbidity, and chronic nephrotoxicity. Adoptive autologous regulatory T-cell therapy may permit safer immunosuppression minimisation, but experience in deceased kidney transplantation remains limited.

ProTreg21 is a single-centre, open-label, controlled phase I/IIa trial using a 3+3 single-ascending-dose design. Eligible adults aged 18-70 years undergoing primary deceased- donor kidney transplantation will receive low-dose rabbit anti-thymocyte globulin (Thymoglobulin; 1.5 mg/kg on days 0 and 1) and standard of care immunosuppression. In addition, participants in the investigational arm will receive a single infusion of ex-vivo expanded autologous polyclonal regulatory T cells (Treg02) at ascending doses of 0.5 × 106, 1 × 106, 3 × 106 cells/kg on day 16 (±2 days). The primary objective is to evaluate safety and tolerability; the primary endpoint is a protocol-defined Treg02 related defined dose-limiting toxicity within 14 days after infusion. Feasibility and longer-term safety will be secondary outcomes, whereas biopsy proven acute rejection, graft function, infection, malignancy, immunosuppression reduction, and immune biomarkers through week 60 will be exploratory outcomes.

Here we describe the approved trial protocol; no trial results are reported.

ProTreg21 will establish whether Treg02 can be manufactured and administered safely following deceased donor kidney transplantation and will provide exploratory data to inform subsequent efficacy trials.