Minimization of immunosuppression in adult liver transplantation: new strategies and tools

Extended follow-up of pediatric liver transplantation patients receiving once daily calcineurin inhibitor

We describe longitudinal results in a cohort of pediatric liver transplant patients successfully minimized to once daily CNI monotherapy for longer than five yr and assess changes in liver biochemistries and liver histology. A retrospective chart review of all pediatric liver transplant patients at a single center was performed. Biopsies and serum biochemistries (AST, ALT, total bilirubin, direct bilirubin, INR, creatinine) are reported at time points: PM, five-yr, seven-yr, and nine-yr post-minimization. Biopsies were assessed for inflammation and fibrosis using Ishak and Batts grading systems. Successful minimization to daily CNI monotherapy was defined as normal liver enzymes with no episodes of rejection. Thirty-three patients have successfully remained on once daily CNI for >5 yr, and 19/33 of these patients have serial liver biopsies available for review. We report on the clinical and histological findings of these 19 patients. All 19 patients continue to have normal liver biochemistries. On post-minimization biopsies, fibrosis progressed by ≥2 stages in one patient (5.3%) despite normal liver biochemistries. Carefully selected patients can tolerate minimization to once daily CNI monotherapy as few have progression of fibrosis.

Challenges to liver transplantation and strategies to improve outcomes

Liver transplantation (LT) is a highly successful treatment for many patients with nonmalignant and malignant liver diseases. However, there is a worldwide shortage of available organs; many patients deteriorate or die while on waiting lists. We review the important clinical challenges to LT and the best use of the scarce organs. We focus on changes in indications for LT and discuss scoring systems to best match donors with recipients and optimize outcomes, particularly for the sickest patients. We also cover controversial guidelines for the use of LT in patients with hepatocellular carcinoma and cholangiocarcinoma. Strategies to increase the number of functional donor organs involve techniques to perfuse the organs before implantation. Partial LT (living donor and split liver transplantation) techniques might help to overcome organ shortages, and we discuss small-for-size syndrome. Many new developments could increase the success of this procedure, which is already one of the major achievements in medicine during the second part of the 20th century.

Belatacept treatment for two yr after liver transplantation is not associated with operational tolerance

Belatacept was recently evaluated in liver transplantation (LT) in a phase II multicenter trial, which was terminated prematurely. Patients were more than two yr post-LT at the time. As high rates of spontaneous tolerance after LT have been reported and as belatacept has marked immunomodulatory effects, we decided to maintain the belatacept patients enrolled at our center (n = 4) on MMF monotherapy. All belatacept patients on MMF monotherapy developed graft dysfunction consistent with acute rejection after a mean period of 10.3 (7-14) wk. Patients were therefore switched to triple therapy with CNI, MMF, and corticosteroids. Graft dysfunction resolved within 1-3 wk after switch. At the time of belatacept discontinuation, mean eGFR was 105.1 mL/min/1.73 m² (92.1-118.9) in belatacept patients compared to 58 mL/min/1.73 m² (36.1-98.2) in controls (p = 0.022). One yr after the switch to CNI therapy, eGFR had declined by 27.4 mL (19.2-39.3; p = 0.008). Thus, LT patients treated with belatacept show superior kidney function that declines upon institution of CNIs. MMF monotherapy following withdrawal of belatacept is associated with a high incidence of graft dysfunction. Belatacept has no obvious immunomodulatory effects in LT recipients that would be sufficient to allow drug withdrawal with a high rate of success.

Trial of complete weaning from immunosuppression for liver transplant recipients: factors predictive of tolerance

Recipients of liver transplantation (LT) may develop immunological tolerance. Factors predictive of tolerance are not clearly understood. Transplant recipients with normal liver function tests and without active viral hepatitis or autoimmune disease who presented with side effects of immunosuppression or a high risk of de novo malignancies were selected to participate in this prospective study. Twenty-four patients fulfilled the inclusion criteria and, therefore, underwent a gradual reduction of immunosuppression. Tolerance was defined as normal liver function tests after immunosuppression withdrawal. Basal clinical and immunological characteristics, including lymphocyte counts and subpopulations (T, B, natural killer, CD4(+) , CD8(+) , and regulatory T cells) and the phytohemagglutinin stimulation index (SI), were compared for tolerant and nontolerant patients. Fifteen of the 24 patients (62.5%) were tolerant at a median of 14 months (interquartile range = 8.5-22.5 months) after complete immunosuppression withdrawal. Tolerant patients had a longer median interval between transplantation and inclusion in the study (156 for tolerant patients versus 71 months for nontolerant patients, P = 0.003) and a lower median SI (7.49 for tolerant patients versus 41.73 for nontolerant patients, P = 0.01). We identified 3 groups of patients with different probabilities of tolerance: in the first group (n = 7 for an interval > 10 years and an SI < 20), 100% reached tolerance; in the second group (n = 10 for an interval > 10 years and an SI > 20 or an interval < 10 years and an SI < 20), 60% reached tolerance; and in the third group (n = 7 for an interval < 10 years and an SI > 20), 29% reached tolerance. In conclusion, a high proportion of select LT recipients can reach tolerance over the long term. Two simple basal variables-the time from transplantation and the SI-may help to identify these patients.

Posttransplant lymphoproliferative disease following liver transplantation

PURPOSE OF REVIEW

Despite contemporary immunosuppressive regimens, posttransplant lymphoproliferative disease (PTLD) remains a major complication after liver transplantation. This review highlights advances in the understanding of the pathophysiology, diagnosis, and management of PTLD in liver transplant recipients.

RECENT FINDINGS

The spectrum of PTLD after liver transplant ranges from polymorphic lymphoproliferation to high-grade monoclonal lymphoma and is usually related to outgrowth of lymphocytes infected with Epstein-Barr virus (EBV). Risk factors for PTLD include EBV-seronegativity of the recipient, young age, intensity of immunosuppression, and the first year posttransplant. Measurement of EBV load by quantitative polymerase chain reaction assays is an important aid in the surveillance and diagnosis of PTLD although the specificity for PTLD is only about 50% (specificity for EBV is ∼100%). In patients diagnosed with PTLD, management options include reduction of immunosuppression, rituximab, combination chemotherapy, and adoptive immunotherapy. Outcomes have improved because rituximab has been incorporated into treatment regimens, and immunotherapy approaches show promise.

SUMMARY

PTLD is a significant complication after liver transplantation, particularly in children. Advances in early detection approaches have aided in the diagnosis and management of PTLD, but further research to identify better predictive biomarkers is needed to improve risk-based treatment strategies.