TLI- and ATG-Enabled Minimization Protocol in Liver Transplantation (TEMPO-LT)

A Phase 1-2 Prospective Study to Evaluate the Safety and Feasibility of Total Lymphoid Irradiation (TLI) and Anti-Thymocyte Globulin (ATG) in Liver Transplantation Recipients to Induce Immune Tolerance

The unmet medical need in solid organ transplantation is to eliminate the lifelong requirement of powerful immune suppression drug combinations with their attendant side effects, and to prevent immune mediated rejection of the organ transplant. The proposed trial is designed to study if following a 'standard of care' deceased donor liver transplant host conditioning using Total Lymphoid Irradiation (TLI) and Anti-Tthymocyte Globulin (ATG) will result in operational tolerance and ultimately allow for immunosuppression drug minimization or cessation.

It has been hypothesized that the ATG and TLI conditioning regimen post liver transplant will be safe and well tolerated and will result in recipients successfully being withdrawn from immunosuppression within 2 years after liver transplantation. We will test the hypothesis that by using a conditioning regimen of ATG and TLI to induce this operational tolerance will allow immunosuppressive drug minimization and cessation while maintaining normal graft function and without the risk of graft rejection.

Importance of this knowledge:

Operational tolerance occurs spontaneously in a minority of liver transplant recipients; however, predictable and reproducible induction of tolerance remains an unmet need. Building on extensive experience with TLI-based tolerance induction in kidney transplantation at Stanford, this study aims to evaluate whether a non-myeloablative conditioning regimen using TLI and ATG can safely facilitate immunosuppression minimization and withdrawal in liver transplant recipients without the use of donor hematopoietic cell infusion.

Study Overview

• Status: Not yet recruiting
• Conditions: Liver Failure
• Intervention / Treatment: Drug: Anti-Thymocyte Globulin, ATG (Rabbit); Device: Total lymphoid irradiation

• Study Type: Interventional
• Enrollment (Estimated): 12
• Phase: Phase 2; Phase 1

Contacts and Locations

Study Locations

• United States
  • California
    • Stanford, California, United States, 94305
      • Stanford University
      • Contact: Study Team; Phone Number: 650-736-5138; Email: atahsin2@stanford.edu

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Undergoing liver transplantation at Stanford University
• No contraindications to Total Lymphoid Irradiation or rabbit antithymocyte globulin (rATG)

Exclusion Criteria:

• Contraindications to Total Lymphoid Irradiation (e.g. pregnancy, bone marrow suppression or disease, autoimmune disease, prior radiation in the field)
• Contraindications to rATG
• Patients with history of hepatocellular carcinoma (HCC) or other malignancies with exception of non melanoma skin cancer in remission Model of End-Stage Liver Disease (MELD) score > 25 Liver transplants with severe reperfusion syndrome (hemodynamic instability requiring 3 or more pressors after reperfusion) Liver transplant with early allograft dysfunction (Orloff criteria) Diagnosis of hepatitis B Diagnosis of hepatitis C, except for patients that have been treated and eradicated of hepatitis C Virtual and/or flow crossmatch positive (MFI added up to 8000 for each DSA with MFI>1000).

Subject has previously received or is receiving another organ for transplant other than liver Subject is currently on dialysis Recipient or donor is HIV positive Subject has received an ABO incompatible donor Subject has received a donor liver greater than 65 years of age Subject has an active infection at the time of transplant Subject will require immunosuppressive agent other than those prescribed in this study Subject is pregnant or lactating Subject is unlikely to comply with the visits scheduled in the protocol, including protocol biopsies Subject has any form of current substance use, psychiatric disorder or condition that may invalidate communication with the Investigators

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Non-Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Anti-thymocyte globulin and Total Lymphoid Irradiation (synchronous tolerance); Participants undergo a conditioning regimen with Anti-thymocyte globulin of 1.5 mg/kg ATG intravenously over 3 - 4 days immediately after liver transplant surgery and Total Lymphoid Irradiation post liver transplant surgery to induce immune tolerance, which thereby, improves graft engraftment.	Drug: Anti-Thymocyte Globulin, ATG (Rabbit); 1.5 mg/kg ATG will be administered intravenously over 3-4 days. The ATG doses will be completed within 5 days of the liver transplant.; Device: Total lymphoid irradiation; Participants will get 8 doses of TLI over 2 weeks with a total radiation dose of 960 cGy.
Experimental: Anti-thymocyte globulin and Total Lymphoid Irradiation (delayed tolerance); Participants undergo a conditioning regimen with Anti-thymocyte globulin of 1.5 mg/kg ATG intravenously over 3 - 4 days after a while after liver transplant surgery and Total Lymphoid Irradiation post liver transplant surgery to induce immune tolerance, which thereby, improves graft engraftment.	Drug: Anti-Thymocyte Globulin, ATG (Rabbit); 1.5 mg/kg ATG will be administered intravenously over 3-4 days. The ATG doses will be completed within 5 days of the liver transplant.; Device: Total lymphoid irradiation; Participants will get 8 doses of TLI over 2 weeks with a total radiation dose of 960 cGy.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
The success rate	The success rate is defined as the percentage of participants free from all immunosuppressive drugs by 18 months after the start of the conditioning regimen). This will be estimated with standard errors by the Kaplan-Meier procedure and the Greenwood formula.	After intervention through 18 months and monitored monthly up to 36 months.

Collaborators and Investigators

• Sponsor: Stanford University
• Investigators: Principal Investigator: Stephan Busque, MD, MSc, Stanford University

Study record dates

Study Major Dates

• Study Start (Estimated): August 1, 2026
• Primary Completion (Estimated): August 1, 2031
• Study Completion (Estimated): August 1, 2031

Study Registration Dates

• First Submitted: June 4, 2026
• First Submitted That Met QC Criteria: June 4, 2026
• First Posted (Actual): June 9, 2026

Study Record Updates

• Last Update Posted (Actual): June 9, 2026
• Last Update Submitted That Met QC Criteria: June 4, 2026
• Last Verified: June 1, 2026

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Digestive System Diseases; Liver Diseases; Hepatic Insufficiency; Liver Failure; Amino Acids, Peptides, and Proteins; Proteins; Antibodies; Immunoglobulins; Immunoproteins; Blood Proteins; Serum Globulins; Globulins; Biological Products; Complex Mixtures; Immune Sera; Antilymphocyte Serum
• Other Study ID Numbers: 86730

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: Yes
• Studies a U.S. FDA-regulated device product: Yes
• product manufactured in and exported from the U.S.: No