COVID-19 pandemic and potential risks to study participants and study staff.

Antirejection medicines, also known as immunosuppressive drugs, are prescribed to organ transplant recipients to prevent their bodies from rejecting the new organ. Some organ transplant recipients can stop taking anti-rejection medicines without rejecting their transplanted organ (this is called 'tolerance'). The purpose of this study will collect samples and data from 'tolerant' liver or kidney transplant recipients in order to find out:

The purpose of this study is to collect samples and data in order to find out:

• How long liver or kidney transplant recipients can remain tolerant;
• What happens in the tolerant recipient's body over time; and
• If there are patterns in the body that are linked to tolerance.

This is a multi-center, prospective, observational study in which operationally tolerant recipients of liver or kidney allografts will be followed longitudinally, with annual collections of clinical data and biological samples. All participants will be followed for the duration of the study, regardless of changes in their tolerance status.

Participants will be recruited by three main pathways:

1. Tolerant participants from current and past Immune Tolerance Network (ITN) trials, including those who have already completed trial participation and those who are anticipated to complete trial participation,
2. Tolerant participants referred by ITN affiliated investigators, academic and community transplant physicians and directly through outreach to transplant affinity groups such as the National Kidney Foundation (NKF), and
3. Tolerant participants from the general transplant community who are reachable through general contact channels such as the ITN website, word-of-mouth referrals from existing participants, and social media.

Inclusion Criteria:

• Recipient of single organ liver or kidney allograft from a living or deceased donor;

• At screening, operationally tolerant, as defined by:

  • Absence of any immunosuppressive therapy for ≥52 weeks prior to the screening visit, and
  • No evidence of allograft rejection in the 52 weeks prior to the screening visit, based on the allograft recipient's medical history.

• Normal allograft function, defined as:

  • For liver transplant recipients: Liver function tests (ALT, GGT) both less than or equal to the upper limit of normal (ULN); and,
  • For kidney transplant recipients: Serum creatinine value corresponds to an estimated GFR > 45 ml/min/1.73 m^2.

• Receiving regular follow-up for a kidney or liver transplant by a local physician:

  --Participants must be willing to allow the study team to contact and share medical information with this local physician.

• Ability to sign informed consent.

Exclusion Criteria:

• Current malignancy requiring recent surgery, ongoing chemotherapy, or radiation;
• Transplant of another organ;
• Current drug or alcohol dependency;
• Any medical condition that in the opinion of the principal investigator would interfere with safe completion of the trial; and
• Inability to comply with the study visit schedule and required assessments.

Operationally tolerant recipients of liver or kidney allografts

The plan is to share data upon completion of the study in: Immunology Database and Analysis Portal (ImmPort), a long-term archive of clinical and mechanistic data from DAIT-funded grants and contracts.

On average, within 24 months after database lock for the trial.

Open access.

Up to 3.7 years.

Only adverse events that met serious criteria were collected for this study.

Inclusion: A serious adverse event (SAE) that occurred:

• within 24 hours after a protocol-mandated blood draw, or
• if an SAE occurred more than 24 hours after a protocol-mandated blood draw and was deemed as a possibly or definitely association with a protocol-mandated blood draw.

Participants in the "Enrolled, Not Eligible" Arm/Group did not undergo any protocol mandated blood draws and are not represented.

The study team ended the study early due to the COVID-19 pandemic on March 24, 2020.