Immunological Reset to Enable Access to Hla-compatible Kidney Transplantation in Highly Sensitized Patients (RESET)

Overview

The purpose of this clinical trial is to evaluate whether a temporary reprogramming of the immune system can help highly sensitized (hyperimmunized) patients with end-stage kidney disease safely receive a compatible kidney transplant. Patients who are highly sensitized have developed an extremely high level of antibodies against human leukocyte antigens (HLA), often due to previous transplants, pregnancies, or blood transfusions. This condition makes it nearly impossible for them to find a compatible organ donor, leaving them stuck on dialysis indefinitely. This study tests an innovative strategy using Autologous Hematopoietic Stem Cell Transplantation (AHSCT). The procedure involves an intensive conditioning regimen using a combination of medications (cyclophosphamide, thymoglobulin, and rituximab) to deeply clear out the patient's existing mature immune cells. This is followed by the reinfusion of the patient's own previously collected and purified blood stem cells (CD34+ cells) to rebuild the immune system from scratch. The investigators hypothesize that this procedure will eliminate the "immunological memory" cells responsible for producing the problematic anti-HLA antibodies, resetting the immune system to a "naive" or inactive state. This immune reset is expected to eliminate or significantly lower circulating HLA antibodies, creating a critical window of opportunity for these patients to successfully receive a compatible kidney transplant from the deceased-donor waiting list.

This single-center, open-label, non-randomized phase Ib/II pilot study will evaluate the safety, feasibility, and immunological effects of autologous hematopoietic stem cell transplantation (AHSCT) in highly sensitized patients awaiting kidney transplantation. A total of 10 hyperimmunized patients on the kidney transplant waiting list will be enrolled in two sequential phases. In Phase 1, four participants will undergo AHSCT with close safety monitoring during a 12-month follow-up period. In the absence of severe adverse events, participants will be reactivated on the deceased-donor kidney transplant waiting list at 6 months post-AHSCT. Following safety evaluation of the initial cohort, an additional six participants will be enrolled in Phase 2 to further assess the efficacy and safety of the strategy. The intervention includes a non-myeloablative lymphodepletion and stem cell mobilization regimen followed by collection, CD34+ selection, and reinfusion of autologous hematopoietic progenitor cells. After AHSCT, eligible participants may undergo deceased-donor kidney transplantation following confirmation of HLA compatibility by standard crossmatch techniques. Kidney transplant recipients will receive standard-of-care induction and maintenance immunosuppressive therapy according to institutional clinical practice. The study also includes longitudinal immunological monitoring to characterize adaptive immune reconstitution and anti-HLA responses after AHSCT and kidney transplantation. Peripheral blood and bone marrow samples will be collected at predefined time points to evaluate T- and B-cell memory compartments, donor-specific antibodies, and pathogen-specific immune responses. Primary objectives include assessment of safety and feasibility, as well as evaluation of changes in sensitization status and access to HLA-compatible kidney transplantation following AHSCT.