Longterm Survival and Cost-Effectiveness of Immunosuppression Withdrawal After Liver Transplantation

Time since liver transplant and immunosuppression withdrawal outcomes: Systematic review and individual patient data meta-analysis

BACKGROUND & AIMS

Successful immunosuppression withdrawal (ISW) is possible for a subfraction of liver transplant (LT) recipients but the factors that define the risk of ISW failure are largely unknown. One candidate prognostic factor for ISW success or operational tolerance (OT) is longer time between LT and ISW which we term "pre-withdrawal time". To clarify the impact of pre-withdrawal time span on subsequent ISW success or failure, we conducted a systematic review with meta-analysis.

METHODS

We systematically interrogated the literature for LT recipient ISW studies reporting pre-withdrawal time. Eligible articles from Embase, Medline, and the Cochrane Central Register of Controlled Trials were used for backward and forward citation searching. Pre-withdrawal time individual patient data (IPD) was requested from authors. Pooled mean differences and time-response curves were calculated using random-effects meta-analyses.

RESULTS

We included 17 studies with 691 patients, 15 of which (620 patients) with IPD. Study-level risk of bias was heterogeneous. Mean pre-withdrawal time was greater by 427 days [95% confidence interval (CI) 67-788] in OT compared to non-OT patients. This increase was potentiated to 799 days (95% CI 369-1229) or 1074 days (95% CI 685-1463) when restricting analysis to adult or European study participants. In time-response meta-analysis for adult or European ISW candidates, likelihood of OT increased by 7% (95% CI 4-10%) per year after LT (GRADE low- and moderate-certainty of evidence, respectively).

CONCLUSIONS

Our data support the impact of pre-withdrawal time in ISW decision-making for adult and European LT recipients.

PROSPERO REGISTRATION

CRD42021272995.

Balancing immunosuppression in pediatric liver transplantation: Playing the long game

The overarching goal in the care of pediatric liver transplant recipients is to optimize allograft and patient health. Balancing immunosuppression to maintain allograft health while avoiding medication side effects is essential for long-term survival and optimal quality of life in pediatric liver transplant recipients. Utilizing precision medicine to personalize immunosuppression, which includes minimization and withdrawal, is core to this effort. The unique anatomy and physiology of the liver make it more tolerant to immune-mediated injury and a more favorable organ for immunosuppression minimization and withdrawal. However, several challenges exist. Standard biochemical values and histologic features may not reliably predict allograft health after a reduction in immunosuppression. Additionally, biochemical values alone do not reliably identify which patients can successfully develop operational tolerance, as there may be occult allograft injury despite normal liver enzymes. Finally, the durability of tolerance after successful reduction in immunosuppression remains uncertain over time. Innovative tools show promise in circumventing these challenges, but more research is needed to determine actual clinical utility. While immunosuppression-free transplant may not be a current reality for most pediatric liver transplant recipients, strategies to safely minimize immunosuppression without compromising allograft health are within reach. Each liver allograft and recipient pair requires a different degree of immune modulation, and through a structured process of minimization and withdrawal, immunosuppression can indeed be tailored in a precise, personalized way to optimize outcomes. This review focuses on the progress that has been made to individualize immunosuppression in pediatric liver transplantation to ensure optimal allograft and recipient health.

Cell transplantation-based regenerative medicine in liver diseases

This review aims to evaluate the current preclinical state of liver bioengineering, the clinical context for liver cell therapies, the cell sources, the delivery routes, and the results of clinical trials for end-stage liver disease. Different clinical settings, such as inborn errors of metabolism, acute liver failure, chronic liver disease, liver cirrhosis, and acute-on-chronic liver failure, as well as multiple cellular sources were analyzed; namely, hepatocytes, hepatic progenitor cells, biliary tree stem/progenitor cells, mesenchymal stromal cells, and macrophages. The highly heterogeneous clinical scenario of liver disease and the availability of multiple cellular sources endowed with different biological properties make this a multidisciplinary translational research challenge. Data on each individual liver disease and more accurate endpoints are urgently needed, together with a characterization of the regenerative pathways leading to potential therapeutic benefit. Here, we critically review these topics and identify related research needs and perspectives in preclinical and clinical settings.

Liver transplantation for colorectal secondaries: on the way to validation

PURPOSE OF REVIEW

Liver transplantation for nonresectable colorectal liver metastases (CRLMs) is an emerging field within transplant oncology. This review summarizes recent developments within this field.

RECENT FINDINGS

More stringent selection criteria can yield 5-year survival rates that are similar to conventional indications for liver transplantation. Response to chemotherapy, low carcinoembryonic antigen levels, limited tumor volume and stable disease with observation time exceeding 12 months are fundamental requirements in this context. Radiomic analysis of pre transplant PET/computed tomography scans to determine metabolic tumor volume (MTV) in the liver seems particularly promising with regards to prediction of a favorable tumor biology. MTV values below 70 cm3 are associated with excellent long-term survival after transplantation, whereas the MTV threshold for liver resection seem far smaller. Recent studies put into question whether technical nonresectability per se is a valid inclusion criterion for liver transplantation. In patients with high hepatic tumor burden, but otherwise favorable prognostic features as assessed by the Oslo score, liver transplantation could possibly give a clinically relevant survival benefit compared with liver resection.

SUMMARY

Liver transplantation is feasible treatment option in highly selected patients with nonresectable CRLMs. Robust and stringent selection criteria should be applied according to international consensus guidelines.

Outcome and safety of a surveillance biopsy guided personalized immunosuppression program after liver transplantation

Graft survival beyond year 1 has not changed after orthotopic liver transplantation (OLT) over the last decades. Likewise, OLT causes comorbidities such as infection, renal impairment and cancer. We evaluated our single-center real-world individualized immunosuppression program after OLT, based on 211 baseline surveillance biopsies (svLbx) without any procedural complications. Patients were classified as low, intermediate and high rejection risk based on graft injury in svLbx and anti-HLA donor-specific antibodies. While 32% of patients had minimal histological inflammation, 57% showed histological inflammation and 23% advanced fibrosis (>F2), which was not predicted by lab parameters. IS was modified in 79% of patients after svLbx. After immunosuppression reduction in 69 patients, only 5 patients showed ALT elevations and three of these patients had a biopsy-proven acute rejection, two of them related to lethal comorbidities. The rate of liver enzyme elevation including rejection was not significantly increased compared to a svLbx control cohort prior to the initiation of our structured program. Immunosuppression reduction led to significantly better kidney function compared to this control cohort. In conclusion, a biopsy guided personalized immunosuppression protocol after OLT can identify patients requiring lower immunosuppression or patients with graft injury in which IS should not be further reduced.

Clinical parameters and biomarkers predicting spontaneous operational tolerance after liver transplantation: A scoping review

Indefinite allograft acceptance after immunosuppression withdrawal (ISW), also known as operational tolerance (OT), can occur spontaneously after liver transplantation (LT), but reliable and reproducible prognosis of OT versus non-OT outcomes remains elusive. To prime this, systematic extraction of OT-predictive factors from the literature is crucial. We provide the first comprehensive identification and synthesis of clinical parameters and biomarkers predicting spontaneous OT in non-autoimmune/non-replicative viral LT recipients selected for ISW. We searched Embase, Medline, the Cochrane Central Register of Controlled Trials, clinicaltrials.gov, and the World Health Organization International Clinical Trials Registry Platform for articles, conference abstracts, and ongoing trials. We contacted principal investigators of stand-alone abstracts and ongoing trials for unpublished data and screened citations and references of eligible articles. Twenty-three articles reporting on 11 completed ISW studies, 13 abstracts, and five trial registry entries were included. Longer time between LT and ISW was the only clinical parameter that may increase the incidence of OT. Prognostic biomarkers conspicuously differed between pediatric and adult ISW candidates. These included allograft gene expression patterns and peripheral blood immune exhaustion markers for adults, and histological allograft scores for children. Our results will foster cross-validation efforts to facilitate safe and harmonized candidate selection for successful ISW.

Access to Liver Transplantation for Hepatocellular Carcinoma: Does Candidate Age Matter?

BACKGROUND

Liver transplantation (LT) offers an effective alternative treatment for unresectable hepatocellular carcinoma (HCC). Despite its growing acceptance and longer life expectancy rates, survival data in older patients are conflicting and consensus guidelines are lacking in terms of a cut-off age range for operations.

STUDY DESIGN

We explored our prospectively maintained institutional database to identify patients diagnosed with HCC between January 1, 2002 and December 31, 2019. Long-term oncologic outcomes were analyzed in patients undergoing LT or hepatic resection, with patient age considered as the primary variable.

RESULTS

In total, 1,629 patients with HCC were identified, of whom 700 were considered for curative operations (LT, n = 538; resection, n = 162). Patients older than 65 years were less likely to be considered for LT (p < 0.01), although there were no age-related differences in the de-listing rate among age groups (p = 0.90). Older patients had overall survival (OS) outcomes comparable with younger patients after LT (3-year OS: 85.5% vs 84%; 5-year OS: 73.9% vs 77%; p = 0.26). Long-term survival was lower in the group who underwent resection, however, older patients still demonstrated equivalent OS outcomes (3-year OS: 59% vs 64.8%; 5-year OS: 44.8% vs 49%; p = 0.13). There were no differences in the development of local or distant metastatic disease between groups.

CONCLUSIONS

Although older candidates were less likely to be considered for LT in the management of HCC, judicious matching can lead to OS data comparable with their younger counterparts. Previous age misconceptions need to be challenged without the concern of worse long-term oncologic outcomes after surgery.

A Large-Scale Bank of Organ Donor Bone Marrow and Matched Mesenchymal Stem Cells for Promoting Immunomodulation and Transplant Tolerance

Induction of immune tolerance for solid organ and vascular composite allografts is the Holy Grail for transplantation medicine. This would obviate the need for life-long immunosuppression which is associated with serious adverse outcomes, such as infections, cancers, and renal failure. Currently the most promising means of tolerance induction is through establishing a mixed chimeric state by transplantation of donor hematopoietic stem cells; however, with the exception of living donor renal transplantation, the mixed chimerism approach has not achieved durable immune tolerance on a large scale in preclinical or clinical trials with other solid organs or vascular composite allotransplants (VCA). Ossium Health has established a bank of cryopreserved bone marrow (BM), termed "hematopoietic progenitor cell (HPC), Marrow," recovered from deceased organ donor vertebral bodies. This new source for hematopoietic cell transplant will be a valuable resource for treating hematological malignancies as well as for inducing transplant tolerance. In addition, we have discovered and developed a large source of mesenchymal stem (stromal) cells (MSC) tightly associated with the vertebral body bone fragment byproduct of the HPC, Marrow recovery process. Thus, these vertebral bone adherent MSC (vBA-MSC) are matched to the banked BM obtained from each donor, as opposed to third-party MSC, which enhances safety and potentially efficacy. Isolation and characterization of vBA-MSC from over 30 donors has demonstrated that the cells are no different than traditional BM-MSC; however, their abundance is >1,000-fold higher than obtainable from living donor BM aspirates. Based on our own unpublished data as well as reports published by others, MSC facilitate chimerism, especially at limiting hematopoietic stem and progenitor cell (HSPC) numbers and increase safety by controlling and/or preventing graft-vs.-host-disease (GvHD). Thus, vBA-MSC have the potential to facilitate mixed chimerism, promote complementary peripheral immunomodulatory functions and increase safety of BM infusions. Both HPC, Marrow and vBA-MSC have potential use in current VCA and solid organ transplant (SOT) tolerance clinical protocols that are amenable to "delayed tolerance." Current trials with HPC, Marrow are planned with subsequent phases to include vBA-MSC for tolerance of both VCA and SOT.

The Revolution in Indication for Liver Transplantation: Will Liver Metastatic Disease Overcome the End-Stage Liver Disease in the Next Future?

Indications for liver transplantation (LT) have constantly been evolving during the last few decades due to a better understanding of liver diseases and innovative therapies. Likewise, also the underlying causes of liver disease have changed. In the setting of transplant oncology, recent developments have pushed the boundaries of oncological indications for LT outside hepatocellular carcinoma (HCC), especially for secondary liver tumors, such as neuroendocrine and colorectal cancer. In the next years, as more evidence emerges, LT could become the standard treatment for well-selected metastatic liver tumors. In this manuscript, we review and summarize the available evidence for LT in liver tumors beyond HCC with a focus on metastatic liver malignancies, highlighting the importance of these new concepts for future implications.

Pregnancy Weight Gain as a Predictor of Fetal Wellbeing in Liver Transplant Recipients

BACKGROUND Gestational weight gain (GWG) is an important index influencing perinatal outcomes. Inappropriate weight gain during pregnancy is strongly associated with multiple pregnancy complications. In pregnant liver transplant recipients whose risk of adverse pregnancy outcomes is already high, this aspect may be even more significant. The present study analyzed the gestational weight gain in female liver transplant recipients and its effect on neonatal complications. MATERIAL AND METHODS A cohort study of retrospective data was performed in the 1st Department of Obstetrics and Gynecology, Medical University of Warsaw. There were 23 patients who fulfilled all inclusion criteria. The gestational weight gain was analyzed in the context of pre-pregnancy BMI, immunosuppression, and perinatal outcomes. RESULTS The preterm delivery rate was 39.13% and GWG increased according to the duration of pregnancy. The model adjusted to week of delivery revealed no association between weight gain and the length of pregnancy (p=0.82). GWG in liver transplant recipients did not affect hypotrophy incidence, adverse perinatal outcomes, or caesarian delivery rate. A positive correlation between GWG and neonatal birth weight was observed (p=0.06). One patient, with coexisting PIH, had a stillbirth at 23 weeks. In all other cases, the 5-min Apgar score was 10 points. CONCLUSIONS Current obstetrical recommendations do not consider patients with chronic diseases undergoing immunosuppressive treatment. Proper counselling and preparing liver transplant recipients for pregnancy, especially optimizing maternal pre-pregnancy BMI, may be an important element in improving perinatal outcomes by lowering the risk of maternal complications. GWG itself is not relevant as a predictor of term gestation, but it might be important in achieving eutrophic fetus growth.

COVID-19, liver transplant, and immunosuppression: Allies or foes?

Liver transplant (LT) recipients are considered at a particularly high risk for developing critical COVID‐19 infection. To date, available data are heterogeneous and scarce and mortality in LT recipients seems to be higher compared to normal population, but whether this is caused by altered immunological status, immunosuppression (IS), or underlying comorbidities has not yet been fully clarified. Some evidences show that IS might play a role in the pathophysiology of this new disease. We searched all available data regarding LT recipients infected by COVID‐19, focusing on the role of IS. To date, 244 LT recipients have been reported as COVID‐19‐positive. Trends among transplant physicians are to reduce overall IS, especially antimetabolite drugs, but the current available observations are still not enough to build strong evidences for recommendation and IS should be meticulously tailored case by case.

The utility of early post-liver transplantation model for end-stage liver disease score in prediction of long-term mortality

Background:

Little is known about the prognostic ability of post-liver transplantation (LT) model for end-stage liver disease (MELD) score measurement in assessing long-term outcomes. The aim of the present study was to investigate this possible relationship.

Methods:

In this retrospective cohort study, the medical records of LT recipients operated under a LT program were reviewed. The accuracy of post-operation MELD score for predicting mortality was evaluated based on receiver operating characteristic (ROC) curves. Univariate and Cox proportional hazard regression models were used to assess the risk factors associated with mortality.

Results:

Eight hundred twenty-six consecutive LT recipients were included in the study. The areas under the ROC curve on postoperative days (POD) 5 and 9 for predicting 1-year mortality were 0.712 (95% confidence interval [CI] 0.614-0.811) and 0.682 (95%CI 0.571-0.798), respectively. A cutoff point of 14.5 was obtained for MELD score on POD5 that significantly differentiated between survivors and non-survivors with a sensitivity of 69.8% (95%CI 50.7-83.1) and a specificity of 57.2% (95%CI 50.6-63.6). In the Cox multivariate analysis, factors including MELD score on POD5 (hazard ratio [HR] 1.83, 95%CI 1.07-3.12; P=0.026), pre-transplant MELD (HR 1.064, 95%CI 1.025-1.104; P=0.001) and operation duration (min) (HR 1.004, 95%CI 1.003-1.006; P=0.013) were identified as independent risk factors for predicting overall survival.

Conclusion:

The immediate postoperative MELD scores after LT may be of value in predicting mortality and could be used as a tool for postoperative risk assessment of patients.

De novo malignancies after liver transplantation: The effect of immunosuppression-personal data and review of literature

BACKGROUND

Immunosuppression has undoubtedly raised the overall positive outcomes in the post-operative management of solid organ transplantation. However, long-term exposure to immunosuppression is associated with critical systemic morbidities. De novo malignancies following orthotopic liver transplants (OLTs) are a serious threat in pediatric and adult transplant individuals. Data from different experiences were reported and compared to assess the connection between immunosuppression and de novo malignancies in liver transplant patients.

AIM

To study the role of immunosuppression on the incidence of de novo malignancies in liver transplant recipients.

METHODS

A systematic literature examination about de novo malignancies and immunosuppression weaning in adult and pediatric OLT recipients was described in the present review. Worldwide data were collected from highly qualified institutions performing OLTs. Patient follow-up, immunosuppression discontinuation and incidence of de novo malignancies were reported. Likewise, the review assesses the differences in adult and pediatric recipients by describing the adopted immunosuppression regimens and the different type of diagnosed solid and blood malignancy.

RESULTS

Emerging evidence suggests that the liver is an immunologically privileged organ able to support immunosuppression discontinuation in carefully selected recipients. Malignancies are often detected in liver transplant patients undergoing daily immunosuppression regimens. Post-transplant lymphoproliferative diseases and skin tumors are the most detected de novo malignancies in the pediatric and adult OLT population, respectively. To date, immunosuppression withdrawal has been achieved in up to 40% and 60% of well-selected adult and pediatric recipients, respectively. In both populations, a clear benefit of immunosuppression weaning protocols on de novo malignancies is difficult to ascertain because data have not been specified in most of the clinical experiences.

CONCLUSION

The selected populations of tolerant pediatric and adult liver transplant recipients greatly benefit from immunosuppression weaning. There is still no strong clinical evidence on the usefulness of immunosuppression withdrawal in OLT recipients on malignancies. An interesting focus is represented by the complete reconstitution of the immunological pathways that could help in decreasing the incidence of de novo malignancies and may also help in treating liver transplant patients suffering from cancer.