Cytokeratin 18 Non-invasive Biomarker for Rejection in Liver Transplant Patients

Cellular rejection following liver transplantation is of worldwide occurrence and a major cause of morbidity affecting 15 to 20 percent of liver transplantation recipients. Elevation of serum aminotransferase may be suspicious of rejection and typically precedes clinical symptoms of fever and jaundice. However, such clinical signs as well biochemical parameters are neither specific nor sensitive for detection of rejection or its degree of severity.

The current standard of care remains a liver biopsy for confirmation of transplant rejection. While significant procedural advances have been made, liver biopsy is an invasive procedure, requiring sedation, and has a small but definite risk of complications including mortality. Developing noninvasive biomarkers which could mitigate the need for an invasive liver biopsy remains a major national and international research focus in the field of hepatology. This could also lay the foundation for early non-invasive longitudinal tracking of rejection and help in decreasing graft failure.

Cytokeratin 18 is a cytoskeletal protein found in hepatocytes and is thought to be a major intermediate filament protein linked to the morphological changes of cell death. During hepatocyte apoptosis, cytokeratin 18 is cleaved by caspases. The resulting novel neo-epitope occurs specifically during apoptosis and represents apoptotic cell death. M30 a monoclonal antibody recognizes this cleaved epitope (CK-18) and thus serves as a novel biomarker for apoptosis. Apoptosis is a known event in rejection. Several mechanisms have been postulated to lead to apoptosis during rejection which include granule-exocytosis pathway, the Fas-mediated pathway and induction by cytokines. Additionally, there appears to be a significant co-relation between the grade of rejection and severity of apoptosis.

These observations lead us into the exciting possibility that CK-18 measurements could prove to be a very valuable noninvasive biomarker for hepatic cellular rejection and could pave the path towards predictive models tracking rejection and its progression. The purpose of this research study is to collect blood samples to be tested for measuring CK-18 levels, assess certain other markers in the blood, and assess the history.

Approximately 105 patients will be enrolled in this study at Saint Louis University.

This is a prospective study that includes three specific cohorts of subjects as follows (no randomization of subjects):

1. Post-transplant patients undergoing standard-of-care liver biopsy (Biopsy arm).
2. Stable post-liver transplantation patients without rejection (Stable post-liver transplant arm).
3. Healthy non-transplant control patients without liver disease (Healthy arm).

Each participant will be assigned a unique participant ID at the time of enrollment. All participants' data and samples collected will be saved by this unique participant ID. All blood samples will be labeled with a study number and sent for assessment of CK-18 levels and other markers to understand rejection.

A participant may spend less than one hour on this research study (the time it takes to give consent, review medical information, and have their blood drawn).

Reviewing their medical records will collect Information about participants (age, race, gender) and their health. The research team will try to take the research blood sample when participants already have a blood test done for their regular health checks, but there may be times when the participant must have blood drawn just for the study.

The blood sample required for this research study will be collected as follows, depending on the participant category may fall into:

1. If the participant is a healthy patient or a participant who underwent liver transplantation and is stable post-transplantation with no symptoms and signs of rejection. In that case, the research sample will be collected with the standard of care lab work they will have as a part of routine healthcare. If such is not possible, the Participant may need to get an extra stick.
2. If a participant is undergoing a liver biopsy. In that case, an intravenous line is usually placed as a standard of care at participating centers at the time of liver biopsy - especially in the pediatric population. Research blood would be collected during line placement or with standard-of-care lab work.

If such cannot be obtained, then the research-only blood sample would be collected. There may be times when the research team is unable to get adequate blood for our research study at this time, which is when participants may need to have additional blood drawn for the study.

Participants may be re-enrolled in the study more than once if they qualify. Participants will be asked if they are willing to participate each time and will be re-consented each time.

• If a participant has a liver transplant after completing participation in the healthy arm, the Participant may be eligible for re-enrollment in the study under other arms (Stable post-liver transplant arm or biopsy arm).
• If a participant has an episode of rejection and is scheduled for liver biopsy after completing participation in the stable post-liver transplant arm, the participant may be eligible for re-enrollment in the study under the biopsy arm since this study captures the rejection events.
• If a participant has a subsequent episode of rejection and is scheduled for another liver biopsy after completing participation in the biopsy arm, the Participant may be eligible for re-enrollment in the study under the liver biopsy arm since this study captures the rejection events.
• If a participant get stable in the study doctor's opinion after completing participation in the biopsy arm. The participant may be eligible for re-enrollment in the study under the stable post-liver transplant arm.