Bridget Flynn

WEANING OF IMMUNOSUPPRESSION IN LIVER TRANSPLANT RECIPIENTS

Immunosuppression has been sporadically discontinued by noncompliant liver allograft recipients for whom an additional 4 1/2 years of follow-up is provided. These anecdotal observations prompted a previously reported prospective drug withdrawal program in 59 liver recipients. This prospective series has been increased to 95 patients whose weaning was begun between June 1992 and March 1996, 8.4+/-4.4 (SD) years after liver replacement. A further 4 1/2 years follow-up was obtained of the 5 self-weaned patients. The prospectively weaned recipients (93 livers; 2 liver/kidney) had undergone transplantation under immunosuppression based on azathioprine (AZA, through 1979), cyclosporine (CsA, 1980-1989), or tacrolimus (TAC, 1989-1994). In patients on CsA or TAC based cocktails, the adjunct drugs were weaned first in the early part of the trial. Since 1994, the T cell-directed drugs were weaned first. Three of the 5 original self-weaned recipients remain well after drug-free intervals of 14 to 17 years. A fourth patient died in a vehicular accident after 11 years off immunosuppression, and the fifth patient underwent retransplantation because of hepatitis C infection after 9 drug-free years; their allografts had no histopathologic evidence of rejection. Eighteen (19%) of the 95 patients in the prospective series have been drug free for from 10 months to 4.8 years. In the total group, 18 (19%) have had biopsy proved acute rejection; 7 (7%) had a presumed acute rejection without biopsy; 37 (39%) are still weaning; and 12 (13%, all well) were withdrawn from the protocol at reduced immunosuppression because of noncompliance (n=8), recurrent PBC (n=2), pregnancy (n=1), and renal failure necessitating kidney transplantation (n=1). No patients were formally diagnosed with chronic rejection, but 3 (3%) were placed back on preexisting immunosuppression or switched from cyclosporine (CsA) to tacrolimus (TAC) because of histopathologic evidence of duct injury. Two patients with normal liver function died during the trial, both from complications of prior chronic immunosuppression. No grafts suffered permanent functional impairment and only one patient developed temporary jaundice. Long surviving liver transplant recipients are systematically overimmunosuppressed. Consequently, drug weaning, whether incomplete or complete, is an important management strategy providing it is done slowly under careful physician surveillance. Complete weaning from CsA-based regimens has been difficult. Disease recurrence during drug withdrawal was documented in 2 of 13 patients with PBC and could be a risk with other autoimmune disorders.

Weaning of immunosuppression in long-term liver transplant recipients.

Seventy-two long-surviving liver transplant recipients were evaluated prospectively, including a baseline allograft biopsy for weaning off of immunosuppression. Thirteen were removed from candidacy because of chronic rejection (n = 4), hepatitis (n = 2), patient anxiety (n = 5), or lack of cooperation by the local physician (n = 2). The other 59, aged 12-68 years, had stepwise drug weaning with weekly or biweekly monitoring of liver function tests. Their original diagnoses were PBC (n = 9), HCC (n = 1), Wilsons disease (n = 4), hepatitides (n = 15), Laennecs cirrhosis (n = 1), biliary atresia (n = 16), cystic fibrosis (n = 1), hemochromatosis (n = 1), hepatic trauma (n = 1), alpha-1-antitrypsin deficiency (n = 9), and secondary biliary cirrhosis (n = 1). Most of the patients had complications of long-term immunosuppression, of which the most significant were renal dysfunction (n = 8), squamous cell carcinoma (n = 2) or verruca vulgaris of skin (n = 9), osteoporosis and/or arthritis (n = 12), obesity (n = 3), hypertension (n = 11), and opportunistic infections (n = 2). When azathioprine was a third drug, it was stopped first. Otherwise, weaning began with prednisone, using the results of corticotropin stimulation testing as a guide. If adrenal insufficiency was diagnosed, patients reduced to < 5 mg/day prednisone were considered off of steroids. The baseline agents (azathioprine, cyclosporine, or FK506) were then gradually reduced in monthly decrements. Complete weaning was accomplished in 16 patients (27.1%) with 3-19 months drug-free follow-up, is progressing in 28 (47.4%), and failed in 15 (25.4%) without graft losses or demonstrable loss of graft function from the rejections. This and our previous experience with self-weaned and other patients off of immunosuppression indicate that a significant percentage of appropriately selected long-surviving liver recipients can unknowingly achieve drug-free graft acceptance. Such attempts should not be contemplated until 5-10 years posttransplantation and then only with careful case selection, close monitoring, and prompt reinstitution of immunosuppression when necessary.

Dendritic cell subset ratio in peripheral blood correlates with successful withdrawal of immunosuppression in liver transplant patients.

Human dendritic cell (DC) subsets appear to play distinct roles in the induction and regulation of immune responses. While monocytoid DC (DC1) induce T‐helper (Th) 1‐type responses, plasmacytoid DC (DC2) have been reported to selectively induce Th2 responses. In blood, their precursors (p) can be identified as HLA‐DR+ lineage– cells that are further characterized as CD11c+ CD123–/lo (IL‐3Rα–/lo) (pDC1) or as CD11c– CD123hi (pDC2) by rare event, flow cytometric analysis. We compared the incidences of pDC1 and pDC2 in peripheral blood mononuclear cell populations isolated from normal healthy controls and from 3 groups of clinically stable liver transplant patients. Group A had been successfully withdrawn from immunosuppression, whereas group B were undergoing prospective drug weaning and on minimal anti‐rejection therapy. In group C, drug withdrawal had either failed or never been attempted and patients were on maintenance immunosuppression. Assessment of DC subsets and the pDC2 : pDC1 ratio showed good intra‐and interassay reproducibility. Compared with patients in group C, those in groups A and B demonstrated a significantly higher relative incidence of pDC2 and a lower incidence of pDC1 – similar to those values observed in normal healthy controls. Moreover, the pDC2 : pDC1 ratio was significantly higher in patients undergoing (successful) weaning and in those off immunosuppression compared with patients on maintenance immunosuppression.

Use of Alemtuzumab and Tacrolimus Monotherapy for Cadaveric Liver Transplantation: With Particular Reference to Hepatitis C Virus

We have proposed that the mechanisms of alloengraftment and variable acquired tolerance can be facilitated by minimum posttransplant immunosuppression. It was further suggested that the efficacy of minimalistic treatment could be enhanced by preoperative recipient conditioning with an antilymphoid antibody preparation. A total of 76 adults (38 hepatitis C virus [HCV]−, 38 HCV+) were infused with 30 mg alemtuzumab before primary cadaveric liver transplantation and maintained afterward on daily monotherapy unless breakthrough rejection mandated additional agents. In stable patients, the intervals between tacrolimus doses were lengthened (“spaced weaning”) after approximately 4 months. Eighty-four contemporaneous nonlymphoid-depleted liver recipients (58 HCV−, 26 HCV+) were treated with conventional postoperative immunosuppression. The overall incidence of rejection was similar with the two strategies of immunosuppression. With follow-ups of 14 to 22 months, patient and primary graft survival in HCV− cases are 97% and 90%, respectively, with alemtuzumab depletion plus minimal immunosuppression versus 71% and 70%, respectively, under conventional immunosuppression. In HCV+ recipients, current patient and graft survival in the alemtuzumab-pretreated group are 71% and 70% versus 65% and 54%, respectively, under conventional treatment. With both strategies of immunosuppression, the adverse effect of preexisting HCV on survival parameters and graft function already was significant at the 1-year milestone, but its extent was not evident until the second year. With or without HCV, 62% of the 64 surviving lymphoid-depleted patients are on spaced immunosuppression, and four patients receive no immunosuppression. Lymphoid depletion with alemtuzumab and minimalistic maintenance immunosuppression is a practical strategy of liver transplantation in HCV− recipients but not HCV+ recipients.

Immunosuppression for liver transplantation in HCV-infected patients: mechanism-based principles.

We retrospectively analyzed 42 hepatitis C virus (HCV)‐infected patients who underwent cadaveric liver transplantation under two strategies of immunosuppression: (1) daily tacrolimus (TAC) throughout and an initial cycle of high‐dose prednisone (PRED) with subsequent gradual steroid weaning, or (2) intraoperative antithymocyte globulin (ATG) and daily TAC that was later space weaned. After 36 ± 4 months, patient and graft survival in the first group was 18/19 (94.7%) with no examples of clinically serious HCV recurrence. In the second group, the three‐year patient survival was 12/23 (52%), and graft survival was 9/23 (39%); accelerated recurrent hepatitis was the principal cause of the poor results. The data were interpreted in the context of a recently proposed immunologic paradigm that is equally applicable to transplantation and viral immunity. In the framework of this paradigm, the disparate hepatitis outcomes reflected different equilibria reached under the two immunosuppression regimens between the relative kinetics of viral distribution (systemically and in the liver) and the slowly recovering HCV‐specific T‐cell response. As a corollary, the aims of treatment of the HCV‐infected liver recipients should be to predict, monitor, and equilibrate beneficial balances between virus distribution and the absence of an immunopathologic antiviral T‐cell response. In this view, favorable equilibria were accomplished in the nonweaned group of patients but not in the weaned group. In conclusion, since the anti‐HCV response is unleashed when immunosuppression is weaned, treatment protocols that minimize disease recurrence in HCV‐infected allograft recipients must balance the desire to reduce immunosuppression or induce allotolerance with the need to prevent antiviral immunopathology. (Liver Transpl 2005;11:1343–1352.)

Risks and benefits of weaning immunosuppression in liver transplant recipients: Long-term follow-up

THE MORBIDITY arising from the chronic use of .1. anti-rejection medications is an incentive to establish the lowest posSIble level of immunosuppression necessary to maintain stable graft function. The finding that freedom from immunosuppression was sporadically possible in longsurviving recipients of liver allografts and the concurrent evidence that chimerism was uniformly demonstrable in such tolerant patients! have led to a prospective trial of complete drug weaning. In our initial experience, it was shown that significant reductions in medication or their discontinuance could be safely accomplished in liver,: and even in a handful of living-related kidney recipients who have been drug free for as long as 30 years.3 However, the danger of consequent allograft rejection has not been completely assessed and guidelines for judicious weaning need to be clarified. We present here further follow-up on our previously reported weaning trial in liver allograft recipients2 and results from additiona.l patients subsequently entered.