Tacrolimus (FK506) and mycophenolate mofetil combination therapy versus tacrolimus in adult liver transplantation

Paradox inflammatory reaction such as appendicitis epiploica and diverticulitis of the sigmoid colon under ongoing immunosuppression after previous liver transplantation (LTx)

Objective

Inflammatory reactions caused by immunosuppression appear a particular interesting disease due to its very specific and partly unclear etiopathogenesis.Based on clinical case-specific management experiences and selective references from the literature, the rare case of an acute intraabdominal inflammation as unusual complication or side effect (at the gastrointestinal [GI] tract) of the ongoing immunosuppressive medication using Mycophenolate mofetil and Tacrolimus after previous liver transplantation is to be illustrated.

Case presentation

Medical history (hx): 1) Current: A 68-years old male patient underwent abdominal CT scan because of pain in the left lower abdomen with the suspicious diagnosis of diverticulitis leading to initiation of antibiotic therapy 24 h prior to the transferral to the own hospital for adequate liver transplantation (LTx) follow-up investigation. 2) Medication contained Sitagliptin 1 × 100 mg, Omeprazol 1 × 40 mg, Mesalazin 500 mg 3 × 2, Movicol 1 (on demand), Mycophenolate mofetil 2 × 500 mg, Tacrolimus 2 × 1 mg and Hydrochlorothiazid 1 × 2.5 mg. 3) Additional diagnoses included arterial hypertension, diabetes mellitus and urinary bladder diverticle. 4) Previous surgical intervention profile comprises resection of liver segments IV/V due to HCC (2011), orthotopic liver transplantation because of HCC caused by alcohol-induced liver cirrhosis (2013) and an intervertebral disc operation (2018). Physical examination of the abdomen revealed marked tenderness in the lower left quadrant. The abdominal wall was soft and there were no defensive tension and no peritonism. The patient was in good general condition and nutritional status. He was cardiopulmonarily stable and oriented to all qualities. Diagnostic measures showed a CRP of 38.0 (normal range, < 5) mg/L and a white blood cell count within normal range. Leading diagnoses were found using abdominal CT scan, which demonstrated an extended diverticulosis and an appendicitis epiploica within the immediate subperitoneal region of the left lower abdomen with an oval fat isodense structure in the region of the sigmoid colon with surrounding inflammatory imbibition and pronounced intestinal wall. Suspicious diagnosis was the 1st episode of an uncomplicated diverticulitis of the sigmoid colon associated with an appendicitis epiploica. Therapeutic approach was given by conservative therapy with infusion therapy, analgesia as well as inital "n. p. o." and following initiation of oral nutrition. In addition, calculated antibiotic therapy with Cefuroxime and Clont was initiated. Clinical course was uneventful, with discharge on the eighth day of hospital stay with no pathological findings and substantial improvement in clinical and laboratory findings. Further advice consisted of clinical and laboratory follow-up control investigations by the family practitioner and nutritional counselling. In addition, a colonoscopy should be performed within four months.

Conclusions

The described case i) is either one of the many side effects of the immunosuppressive medication Mycophenolate mofetil and Tacrolimus listed as "colonic inflammation" and "gastrointestinal inflammation", respectively, or ii) can be considered an inflammatory response of a susceptible (gastro-)intestinal mucosa or the whole intestinal wall to microbes or microbial particles or agents caused by transplantation-associated immunosuppressive medication.

No Influence of Everolimus on Mycophenolic Acid Area Under the Concentration-Time Curve: Limited Sampling Strategy for Mycophenolic Acid in Japanese Kidney Transplant Recipients Treated With Tacrolimus, Mycophenolate Mofetil, Steroid, and Everolimus

BACKGROUND

Despite a growing need for everolimus (EVR) to reduce calcineurin inhibitor toxicity in kidney transplantation (KTx), the influence of EVR on the pharmacokinetics of mycophenolic acid (MPA), a mycophenolate mofetil (MMF) active metabolite, is obscure, and no suitable limited sampling strategy (LSS) for MPA when EVR is concomitantly present exists. We aimed to investigate the influence of EVR on MPA pharmacokinetics in KTx.

MATERIALS AND METHODS

This study complied with all principles of the Declaration of Helsinki. Twenty patients were initially administered tacrolimus, MMF, and methylprednisolone and then received EVR 4 months after KTx. Approximately 4 weeks before and after EVR administration, the estimated value of the area under the concentration-time curve for MPA from 0 to 12 hours (MPA-AUC0-12) was calculated using MPA blood concentration just before and 1, 2, 4, and 6 hours after MMF administration. We compared several MPA pharmacokinetics parameters before and after EVR addition and determined the best estimation equation for LSS of MPA-AUC0-12.

RESULTS

Although MPA-C6 per dose (MPA-C6/D) significantly decreased after EVR addition (from 3.4 [±2.2] ng/mL/g to 2.5 [±0.9] ng/mL/g), MPA-C0/D, -C1/D, -C2/D, -C4/D, and MPA-AUC0-12/D showed no significant change. MPA-AUC0-12/D did not correlate with EVR-AUC0-12/D. The best estimation equation for LSS of MPA-AUC0-12 by 2 time points was [(2.94 × C2) + (5.09 × C4) + 5.32] (R² = 0.73) and [(5.70 × C0) + (1.39 × C1) + 22.45] (R² = 0.72) before and after EVR addition, respectively.

CONCLUSIONS

EVR can be safely combined with MMF after KTx once our results have been reevaluated.

The Need to Update Endpoints and Outcome Analysis in the Rapidly Changing Field of Liver Transplantation

Liver transplantation (LT) survival rates have continued to improve over the last decades, mostly due to the reduction of mortality early after transplantation. The advancement is facilitating a liberalization of access to LT, with more patients with higher risk profiles being added to the waiting list. At the same time, the persisting organ shortage fosters strategies to rescue organs of high-risk donors. This is facilitated by novel technologies such as machine perfusion. Owing to these developments, reconsideration of the current and emerging endpoints for the assessment of the efficacy of existing and new therapies is warranted. While conventional early endpoints in LT have focused on the damage induced to the parenchyma, the fate of the bile duct and the recurrence of the underlying disease have a stronger impact on the long-term outcome. In light of this evolving landscape, we here attempt to reflect on the appropriateness of the currently used endpoints in the field of LT trials.

Anti-Tumor Potential of IMP Dehydrogenase Inhibitors: A Century-Long Story

The purine nucleotides ATP and GTP are essential precursors to DNA and RNA synthesis and fundamental for energy metabolism. Although de novo purine nucleotide biosynthesis is increased in highly proliferating cells, such as malignant tumors, it is not clear if this is merely a secondary manifestation of increased cell proliferation. Suggestive of a direct causative effect includes evidence that, in some cancer types, the rate-limiting enzyme in de novo GTP biosynthesis, inosine monophosphate dehydrogenase (IMPDH), is upregulated and that the IMPDH inhibitor, mycophenolic acid (MPA), possesses anti-tumor activity. However, historically, enthusiasm for employing IMPDH inhibitors in cancer treatment has been mitigated by their adverse effects at high treatment doses and variable response. Recent advances in our understanding of the mechanistic role of IMPDH in tumorigenesis and cancer progression, as well as the development of IMPDH inhibitors with selective actions on GTP synthesis, have prompted a reappraisal of targeting this enzyme for anti-cancer treatment. In this review, we summarize the history of IMPDH inhibitors, the development of new inhibitors as anti-cancer drugs, and future directions and strategies to overcome existing challenges.

Safety of Antithymocyte Globulin in Patients Undergoing Liver Transplantation With Livers From Donation After Circulatory Death Donors

Background: Studies suggest that rabbit-antithymocyte globulin (rATG) decreases biliary complications (BCs) after donation-after-circulatory-death-donor liver transplantation (DCD LTx), but safety data are lacking. Objective: Our aim was to assess the safety of rATG for this indication. The secondary end point was efficacy of rATG for this indication. Methods: Adult recipients of DCD LTx were divided into 2 cohorts: protocolized use of rATG in the modern era (July 1, 2013, to December 31, 2016) and a historical control without rATG (January 1, 2005, to June 30, 2013). Incidence of infection, leukopenia, and thrombocytopenia were compared for the safety assessment, incidence of BCs, ischemic cholangiopathy (IC), and transplant outcomes for the efficacy assessment. Results: A total of 83 patients met inclusion criteria: 42 in the historical cohort and 41 in the modern cohort. The modern cohort had significantly fewer bacterial infections at 3 months (historical 54.8% vs modern 23%; P = 0.004) and 1 year (historical 62.1% vs modern 34.2%, P = 0.004). The modern cohort also had fewer fungal infections at these time points (historical 33.3% and 47.9% vs modern 15% and 15%; P = 0.001). There were no significant differences in platelet or white blood cell reduction between groups. There was a nonsignificant, but numerical, trend toward reduced IC/BC in the modern cohort at 1 year (IC: historical 30.1% vs modern 13.2%, P = 0.08; BC: historical 51% vs modern 37.5%, P = 0.13). There was no difference in graft/patient survival. Conclusion and Relevance: Our data suggest no major safety issues with rATG in DCD LTx. Our study should ease clinical apprehension surrounding rATG use for this indication. Future prospective studies are needed to further evaluate the role of rATG and its impact on efficacy end points.

Reducing Adverse Effects of Immunosuppressive Agents in Kidney Transplant Recipients

Success in solid organ transplantation with minimal complications can now be achieved for most patients, and a remarkable rate of graft and patient survival can also be expected. However, the potential for adverse events and comorbid conditions increases with longer graft survival. Although the immunosuppressive regimen is central to the outcome of the transplant recipient and directly impacts the survival of the graft, chronic use of immunosuppressive agents is associated with metabolic disturbances such as hypertension, hyperlipidemia, loss of bone density, nephrotoxicity, and diabetes, which may contribute to other comorbid conditions. In addition, changes in appearance, gingival hyperplasia, hirsutism, alopecia, and weight gain disrupt quality of life and may lead to noncompliance with the immunosuppressive regimen. New immunosuppressive medications, including mycophenolate mofetil, sirolimus, basiliximab, and daclizumab, have allowed for experimentation with new regimens designed to reduce or allow discontinuation of corticosteroids and calcineurin inhibitors. This review highlights the impact and cost of immunosuppressive side effects and the potential for new immunosuppressive regimens to reduce this substantial clinical burden in transplantation.

Clinical mycophenolic acid monitoring in liver transplant recipients

In liver transplantation, the efficacy of mycophenolate mofetil (MMF) has been confirmed in clinical trials and studies. However, therapeutic drug monitoring for mycophenolic acid (MPA) has not been fully accepted in liver transplantation as no long-term prospective study of concentration controlled vs fixed-dose prescribing of MMF has been done. This review addressed MPA measurement, pharmacokinetic variability and reasons of this variation, exposure related to acute rejection and MMF-associated side effects in liver transplant recipients. Limited sampling strategies to predict MPA area under the concentration-time curve have also been described, and the value of clinical use needs to be investigated in future. The published data suggested that a fixed-dosage MMF regimen might not be suitable and monitoring of MPA exposure seems helpful in various clinical settings of liver transplantation.

A prospective randomized open study in liver transplant recipients: daclizumab, mycophenolate mofetil, and tacrolimus versus tacrolimus and steroids

This open-label, randomized study compared the efficacy of a regimen of corticosteroids and tacrolimus (standard therapy group, n = 79) with a regimen of daclizumab induction therapy in combination with mycophenolate mofetil and tacrolimus (modified therapy group, n = 78) in primary liver transplant recipients. The primary endpoint was biopsy-proven acute rejection (BPAR) at 24 weeks. Secondary endpoints included time to rejection and patient and graft survival. The incidence of BPAR was significantly reduced in the modified therapy group compared to the standard therapy group (11.5% versus 26.6%, respectively, P = 0.017). The time to rejection was significantly shorter in the standard therapy group compared with the modified therapy group (P = 0.044). There was no significant difference between groups in patient or graft survival. Hepatitis C virus-positive patients exhibited no differences from hepatitis C virus-negative patients with respect to the incidence of BPAR. A steroid-sparing regimen of daclizumab, mycophenolate mofetil, and tacrolimus was effective and well tolerated in the prevention of BPAR in adult liver transplant recipients in comparison with a standard regimen of tacrolimus and steroids.

Thymoglobulin induction in liver transplant recipients with a tacrolimus, mycophenolate mofetil, and steroid immunosuppressive regimen: a five-year randomized prospective study

This randomized, comparative study assessed the long-term efficacy and tolerability of thymoglobulin (TMG) induction in 93 liver transplant patients with an initial regimen of tacrolimus (Tac), mycophenolate mofetil (MMF), and steroids. Forty-four patients were randomly allocated to the TMG+ group, and 49 patients were randomly allocated to the TMG- group. In both groups, Tac was given orally at the initial daily dose of 0.075 mg/kg twice daily, and MMF was given at the initial daily dose of 2 g/day. Steroid withdrawal was planned at 3 months after liver transplantation. The results were evaluated with respect to acute rejection incidence, patient and graft survival, graft function, and medical complications until 5 years or death for all patients. No significant differences were found between groups for the incidence of acute rejection at 5 years (11.4% versus 14.3%), 5-year patient survival (77.3% versus 87.8%), graft function, or postoperative renal function. One patient in the TMG- group underwent retransplantation. There was no difference between groups with respect to the incidence of medical complications, excepted for a higher rate of leukopenia in the TMG+ group, during the 5-year follow-up. In conclusion, the results of this prospective randomized study suggest that the addition of TMG to a triple immunosuppressive regimen (Tac, MMF, and steroids) did not modify the incidence of acute rejection episodes or long-term survival and was responsible for increased leukopenia rates.

Pediatric liver transplantation

In previous decades, pediatric liver transplantation has become a state-of-the-art operation with excellent success and limited mortality. Graft and patient survival have continued to improve as a result of improvements in medical, surgical and anesthetic management, organ availability, immunosuppression, and identification and treatment of postoperative complications. The utilization of split-liver grafts and living-related donors has provided more organs for pediatric patients. Newer immunosuppression regimens, including induction therapy, have had a significant impact on graft and patient survival. Future developments of pediatric liver transplantation will deal with long-term follow-up, with prevention of immunosuppression-related complications and promotion of as normal growth as possible. This review describes the state-of-the-art in pediatric liver transplantation.

Pharmacokinetics, efficacy, and safety of mycophenolate mofetil in combination with standard-dose or reduced-dose tacrolimus in liver transplant recipients

The pharmacokinetics of mycophenolate mofetil (MMF) in liver transplant recipients may change because of pharmacokinetic interactions with coadministered immunosuppressants or because changes in the enterohepatic anatomy may affect biotransformation of MMF to mycophenolic acid (MPA) and enterohepatic recirculation of MPA through the hydrolysis of mycophenolate acid glucuronide to MPA in the gut. In the latter case, the choice of formulation (oral versus intravenous) could have important clinical implications. We randomized liver transplant patients (n = 60) to standard (10-15 ng/mL) or reduced (5-8 ng/mL) trough levels of tacrolimus plus intravenous MMF followed by oral MMF (1 g twice daily) with corticosteroids. Pharmacokinetic sampling was performed after the last intravenous MMF dose, after the first oral MMF dose, and at selected times over 52 weeks. The efficacy and safety of the 2 regimens were also assessed. Twenty-eight and 27 patients in the tacrolimus standard-dose and reduced-dose groups, respectively, were evaluated. No significant differences between the tacrolimus standard-dose and reduced-dose groups were seen in dose-normalized MPA values of the time to the maximum plasma concentration (1.25 versus 1.28 hours), the maximum plasma concentration (15.5 +/- 7.93 versus 13.6 +/- 7.03 microg/mL), or the area under the concentration-time curve from 0 to 12 hours (AUC(0-12); 53.0 +/- 20.6 versus 43.8 +/- 15.5 microg h/mL) at week 26 or at any other time point. No relationship was observed between the tacrolimus trough or AUC(0-12) and MPA AUC(0-12). Exposure to MPA after oral and intravenous administration was similar. Safety and efficacy were similar in the two treatment groups. In conclusion, exposure to MPA is not a function of exposure to tacrolimus. The similar safety and efficacy seen with MMF plus standard or reduced doses of tacrolimus suggest that MMF could be combined with reduced doses of tacrolimus.

Delayed introduction of reduced-dose tacrolimus, and renal function in liver transplantation: the 'ReSpECT' study

We report a multicenter, prospective, randomized, open-label trial investigating the effect of lower levels and delayed introduction of tacrolimus on renal function in liver transplant recipients. Adult patients with good renal function undergoing primary liver transplant were randomized to either: group A (standard-dose tacrolimus [target trough levels >10 ng/mL] and corticosteroids; n = 183); group B (mycophenolate mofetil [MMF] 2g/day, reduced-dose tacrolimus [target trough levels </=8 ng/mL], and corticosteroids; n = 170); group C (daclizumab induction, MMF, reduced-dose tacrolimus delayed until the fifth day posttransplant and corticosteroids, n = 172). The primary endpoint was change from baseline in estimated glomerular filtration rate (eGFR) at 52 weeks. The eGFR decreased by 23.61, 21.22 and 13.63 mL/min in groups A, B and C, respectively (A vs C, p = 0.012; A vs B, p = 0.199). Renal dialysis was required less frequently in group C versus group A (4.2% vs. 9.9%; p = 0.037). Biopsy-proven acute rejection rates were 27.6%, 29.2% and 19.0%, respectively. Patient and graft survival was similar. In conclusion, daclizumab induction, MMF, corticosteroids and delayed reduced-dose tacrolimus was associated with less nephrotoxicity than therapy with standard-dose tacrolimus and corticosteroids without compromising efficacy or tolerability.

A single center review of the use of mycophenolate mofetil in the treatment of autoimmune hepatitis

BACKGROUND & AIMS

Standard treatment for autoimmune hepatitis (AIH) involves immune suppression by using prednisone alone or in combination with azathioprine (AZA). Although this regimen achieves remission in approximately 80%, some patients are intolerant or do not respond. Mycophenolate mofetil (MMF) is a potent immunosuppressant. However, its utility in AIH is not well-defined.

METHODS

We performed a retrospective longitudinal analysis of patients with AIH.

RESULTS

We identified 128 patients with AIH: mean age, 42.8 years; 83% female; 69% white. At presentation, median AST and ALT were 227 and 261 U/L, respectively, and bridging fibrosis and cirrhosis were present in 38% and 22%, respectively. Overall, 29 patients received MMF; 12 were switched to MMF after intolerance or nonresponse to prednisone +/- AZA, whereas 17 received MMF +/- prednisone as initial therapy. The main reasons for switching to MMF were nausea/vomiting (n = 4) and failure to normalize liver enzymes (n = 3). Ten of the 29 patients who received MMF therapy (34%) discontinued MMF as a result of side effects. Sixteen (84%) of the remaining 19 patients on MMF achieved remission, which closely matched the remission rate of those who remained on prednisone +/- AZA (82%). The only independent clinical factor that predicted the eventual need for the use of MMF was absence of cirrhosis (P = .0067).

CONCLUSIONS

(1) MMF was associated with a high rate of intolerance (34%). (2) In those who could tolerate it, it was associated with a high rate of remission (84%). (3) Absence of cirrhosis on presentation was the only independent factor associated with eventual need for MMF.

Profile of health-related quality of life outcomes after liver transplantation: univariate effects and multivariate models

AIM

To test the effects of pre- and post-transplant clinical covariates on post-transplant health-related quality of life (HRQOL) score profiles in liver transplant recipients.

MATERIAL AND METHODS

HRQOL was measured before and after transplantation using the SF-36 Health Survey. Clinical data [diagnosis, model of end-stage liver disease (MELD) score, post-transplant rejection and infection episodes], pre-transplant functional performance (FP), and demographics were collected. Multivariate models for the eight SF-36 scales and two summary components were developed using multiple regression. Discriminant analysis was used to test whether the score profiles differentiated among recipients with and without hepatitis C virus (HCV) infection.

RESULTS

104 adults reported pre- and post-transplant HRQOL. Time post-transplant averaged 9+/-8 months (range 1-39). Scores on all SF-36 measures improved from pre- to post-transplant (p<0.001), and 7 of 10 models were significant (p<0.05). After controlling for pre-transplant HRQOL and time post-transplant, HCV infection had a negative effect on the role physical, bodily pain, and role emotional scales. History of a rejection episode had a negative effect on the bodily pain and vitality scales. MELD scores > or = 18 had a positive effect on the role physical scale. Pre-transplant FP and post-transplant infection episodes did not affect post-transplant HRQOL. HCV infection had a significant effect on the SF-36 score profile (canonical correlation=0.50; p<0.001).

CONCLUSIONS

Pre-transplant HCV infection, MELD score, and post-transplant rejection episodes have significant independent effects on HRQOL after liver transplantation. Their specific effects vary among the individual SF-36 scales, and HRQOL score profiles differ among HCV+ and HCV- recipients.

Immunosuppressive agents: effects on glucose and lipid metabolism

Immunosuppressive therapies are critical elements in successful organ transplantation. Although immunosuppressant drugs are essential in preventing graft rejection and graft maintenance after transplantation, their use is complicated by adverse effects, many being detrimental to graft and even patient long-term survival. Commonly used agents are associated with dysregulated glucose metabolism and dyslipidemia. This article focuses on the effects of immunosuppressive agents on glucose and lipid metabolism. Adrenal effects of these drugs, where known, also are discussed.

Laryngeal transplantation: research, clinical experience, and future goals

The loss of a functional voice because of trauma or laryngectomy can have a devastating impact on a patient's self-esteem and overall quality of life. Unfortunately, even with advances in organ preservation therapy, total laryngectomy is frequently necessary in the treatment of laryngeal carcinoma. Over the past several years, the senior author initiated research into laryngeal transplantation with the goal of restoring lung-powered speech for these patients. The research led to the development of an animal model and several groundbreaking studies in this area. Investigations into the use of irradiation, single-drug and multidrug immunosuppression, and the effects of mammalian target of rapamycin (mTOR) inhibitors have produced significant insight into laryngeal allograft preservation. The laboratory research culminated in the first successful total laryngeal transplant in 1998. The patient had suffered significant laryngeal trauma and strongly desired return of laryngeal phonation. The patient has been maintained on multidrug immunosuppression with minimal difficulties. Now more than 8 years after the procedure, the patient continues to have an excellent voice and dramatically improved quality of life. Recent data suggest that altered immunosuppression schedules and the use of mTOR inhibitors may allow patients to minimize immunosuppression-related adverse effects and ameliorate the risk of developing recurrent or de novo carcinoma. These data, when considered in combination with the progress made over the past 14 years, lead us to believe that the future of laryngeal transplantation is bright.

Pharmacokinetics of mycophenolic acid in liver transplant patients after intravenous and oral administration of mycophenolate mofetil

The bioavailability of mycophenolic acid (MPA) after oral administration of mycophenolate mofetil (MMF) has been reported to be more than 90% in healthy volunteers, and in kidney and thoracic organ transplant patients. Such information is limited in liver transplant (LTx) patients. The present study compares the pharmacokinetics of MPA after intravenous (IV) and oral administrations of MMF in LTx recipients. Pharmacokinetic parameters were calculated using WinNonlin software. A total of 12 deceased donor LTx patients initially received IV MMF and were switched to oral MMF after 2-7 days (mean, 3.3 +/- 1.7) when oral feeds were started. Multiple blood samples were drawn immediately prior to and after IV or oral MMF and the plasma concentration of MPA was measured. The mean peak plasma concentrations and the area under the plasma concentration vs. time curve (AUC) were significantly higher after IV MMF compared to oral MMF (peak plasma concentrations of 10.7 +/- 2.1 microg/mL for IV vs. 4.5 +/- 2.8 microg/mL for oral; P = 0.0001; and AUC of 28.9 +/- 7.1 microg . hr/mL for IV vs. 12.8 +/- 4.2 microg . hr/mL for oral; P = 0.0001). The oral bioavailability of MPA was 48.5 +/- 18.7%. The systemic clearance, half-life, and steady state volume of distribution of MPA were 26.9 +/- 6 L/hour, 5.5 hours, and 85 liters, respectively. The terminal disposition half-life was not significantly different between the 2 routes of administration. In conclusion, during the early postoperative period, LTx recipients have MPA exposure with oral MMF of less than half that of IV MMF. Use of IV MMF immediately post-LTx may provide an immunological advantage.

Efficacy of mycofenolate mofetil for steroid-resistant acute rejection after living donor liver transplantation

AIM: To discuss the use of mycophenolate mofetil (MMF) as an immunosuppressant in steroid resistant rejection after liver transplantation.

METHODS: The clinical records of 260 adult patients who underwent living donor liver transplantation (LDLT) were reviewed. Tacrolimus and methylprednisolone were used for primary immunosuppression. Acute rejection was first treated with steroids. When steroid resistance occurred, the patient was treated with a combination of steroids and MMF. Anti-T-cell monoclonal antibody was administered to patients who were not responsive to steroids in combination with MMF.

RESULTS: A total of 90 (35%) patients developed acute rejection. The median interval time from transplantation to the first episode was 15 d. Fifty-four patients were steroid resistant. Forty-four patients were treated with MMF and the remaining 10 required anti-T-cell monoclonal antibody treatment. Progression to chronic rejection was observed in one patient. Bone marrow suppression and gastrointestinal symptoms were the most common side effects associated with MMF use. There was no significant increase in opportunistic infections.

CONCLUSION: Our results demonstrate that MMF is a potent and safe immunosuppressive agent for rescue therapy in patients with acute rejection after LDLT.

Long-term results of mycophenolate mofetil as part of immunosuppressive induction therapy after liver transplantation

BACKGROUND

The addition of mycophenolate mofetil (MMF) to the induction protocol resulted in a lower incidence of rejection episodes. However, the question whether MMF should be administered in combination with tacrolimus or cyclosporine has not been answered yet. In our study, we report on the long-term results of triple induction therapy after orthotopic liver transplantation (OLT), consisting of MMF and low-dose corticosteroids, in combination with either tacrolimus or cyclosporine.

METHODS

Between March 1996 and April 1997, 120 consecutive patients, who underwent OLT at our institution, were enrolled in this study. Of these patients, 80 received triple induction therapy consisting of cyclosporine and MMF (40) or tacrolimus and MMF (40), in combination with low-dose corticosteroids, whereas the remaining 40 patients served as 'MMF-free' control group receiving dual induction therapy with tacrolimus and corticosteroids. Besides the eight-yr follow-up of patient and graft survival, clinical data were also reviewed for episodes of rejection and infection. Additionally, the early post-operative pharmacokinetics of mycophenolic acid (MPA, immunological active metabolite of MMF) were evaluated.

RESULTS

Long-term results provided higher patient and graft survival after tacrolimus/MMF-based induction therapy than after cyclosporine/MMF-based induction therapy. However, the tacrolimus-based control protocol yielded similar results and, therefore, no significantly superior effect was observed when MMF was added. The same observation was made for incidence of rejection and infection episodes. AUC and C(max) of MPA increased in combination with tacrolimus compared with cyclosporine.

CONCLUSIONS

Although pharmacological synergy between tacrolimus and MMF was observed, MMF showed no significant beneficial effects in the immunosuppressive induction protocol, neither in combination with tacrolimus nor with cyclosporine.

Indications of mycophenolate mofetil in liver transplantation

Mycophenolate mofetil (MMF) is approved for prophylaxis of acute rejection after kidney, heart, and liver transplantation as well as for pediatric patients after kidney transplantation. MMF, a noncompetitive inhibitor of inosine monophosphate dehydrogenase (IMPDH), blocks de novo purine synthesis which leads to an effective inhibition of proliferation selectively in T and B lymphocytes, smooth muscle cells, and fibroblasts. MMF shows additional effects with inhibition of the expression of activating and adhesion molecules on the surface of lymphocytes. The beneficial safety profile with distinct side effects compared to calcineurin inhibitors (CNI) enable efficacious combination with ciclosporin or tacrolimus as de novo therapy after liver transplantation. Furthermore, recent studies show the possibility to reduce CNI induced toxicities by adding MMF to primary immunosuppression. MMF is also used to enable early steroid withdrawal after liver transplantation. MMF can increase efficacy of immunosuppressive therapy and thereby support the treatment of steroid resistant acute rejections, chronic rejections and chronic graft dysfunction.

Glomerular and tubular function following orthotopic liver transplantation in children

Since its advent, cyclosporine nephrotoxicity has been a major concern to pediatricians attending to liver transplant recipients. The aims of this study were to examine glomerular and tubular function after orthotopic liver transplantation (OLT) in children, their correlation to CsA, and how they differed according to the underlying disease.

PATIENTS AND METHODS

Glomerular and tubular function was examined in 28 patients aged 7 months to 14 yr at the time of transplantation (mean 4.0 +/- 3.6), retrospectively examining creatinine clearance, tubular phosphate reabsorption (TRP), calcium/creatinine ratio, sodium excretion fraction, and protein/creatinine ratio. The group with metabolic disease and an underlying tubulopathy was compared with the group with liver disease only. The effect of CsA trough levels and cumulated dose on these indices was examined, as was the effect of antihypertensives on creatinine clearance. Both glomerular and tubular functions improved significantly following liver transplantation. In patients on CsA (n = 21), CrCl decreased significantly at 1 month post-OLT (42.6 +/- 26.6 mL/min/1.73 m(2)) when compared with pretransplantation, and 3, 12 and 60 months post-OLT (p < 0.05). It improved between 12 and 60 months post-OLT (p < 0.05). It was correlated with cyclosporine trough levels (p < 0.03), and with total dose of CsA at 12 months. This was not true for patients on tacrolimus (n = 7). Overall pretransplant TRP was below normal (73.7% +/- 19.6), which was significantly lower than the values at years 2, 3, and 5 post-OLT (p < 0.05), owing mainly to the metabolic group which recovered normal proximal tubular function by the end of the second week post-OLT. Calcium/creatinine ratio was significantly worse in the group with liver disease only (p < 0.01). Protein/creatinine ratio normalized rapidly in both groups. Urinary sodium excretion fraction (FENa) was very abnormal in the early postoperative phase, normalizing thereafter in both groups. Kidney function improved after liver transplantation in patients with and without pre-existing kidney dysfunction. Overall, creatinine clearance was correlated to CsA trough levels suggesting CsA did not have an irreversible 'sclerosing' effect in the medium term. Combined antihypertensive therapy using nifedipine and enalapril may be the optimal choice for patients requiring medical management of their hypertension, although the observed effect on creatinine clearance did not reach statistical significance in this study. Tubular dysfunction is frequent in both groups of patients, pre- and post-transplant, and may contribute to bone mineral density as well as to metabolic disturbances in this population.

Mycophenolate mofetil (Cellcept)

Mycophenolate mofetil (MMF) is a new immunosuppressive drug designed to inhibit inosine monophosphate dehydrogenase (IMPDH). IMPDH is a key enzyme in the purine synthesis pathway of lymphocytes. IMPDH is crucially important for the proliferative responses of human T- and B-lymphocytes. Therefore, inhibition of IMPDH leads to selective lymphocyte suppression. Following successful testing in different in vitro and animal models, MMF entered clinical trials, where it has been used in combination with cyclosporin and steroids. MMF has rapid and complete absorption following oral administration. Pilot studies suggested a significant reduction in the incidence of rejection at doses of 1-3 g/day. These data led to the initiation of 3 pivotal trials, in which MMF was compared against different standard immunosuppressive protocols. Nearly 1500 patients were enrolled in these 3 randomised, double-blind, multicentre studies of the addition of MMF to standard immunosuppressive protocols for the prevention of acute renal allograft rejection. After six months, the rate of biopsy-proven rejection was significantly reduced. The adverse event profile resembles that of triple therapy with azathioprine: primarily involving the gastrointestinal (GI) tract, the haematopoietic system and the occurrence of opportunistic infections. MMF affords improved immunosuppressive therapy following renal, and probably other solid organ, transplantation. It is licensed for the prevention of acute renal allograft rejection in most countries around the world.

Tacrolimus in liver transplantation

Tacrolimus has been in clinical use for ten years. It was launched in a hail of publicity following the successful treatment of cases with apparently irreversible rejection using conventional immunosuppressive therapies. Since that time, the overall experience with the drug has increased considerably. The purpose of this article is to review tacrolimus comprehensively, including evidence derived from major clinical trials, to enable the reader to become familiar with its clinical role, including a comparison with its main competitor, cyclosporin. Tacrolimus was discovered in 1984, it predominantly acts via inhibition of T-cell mediated immunity, and to a lesser extent B-cell humoral immunity. The agent was introduced into clinical medicine in 1989 and was soon shown to be a highly effective immunosuppressive agent, receiving approval in 1994 by the Food and Drug Administration (FDA) for primary immunosuppression in adult and paediatric liver transplantation. Tacrolimus has proved to be a major development in transplantation. Whilst the available data have been hindered to some extent by deficiencies of trial design in the major studies, there is still more comparative clinical data available for tacrolimus than for any of its predecessors. The overall balance of risk benefit is considered by many to be tipped in favour of tacrolimus; it is likely that with more long-term follow-up results becoming available in liver and other solid organ transplants, the benefits will appear clearer.

Two-dose Daclizumab Induction Therapy in 209 Liver Transplants: A Single-Center Analysis

BACKGROUND

Patient and graft survival after liver transplantation are adversely affected by early posttransplant renal dysfunction. Therefore, our immunosuppressive strategies should be as "renal sparing" as possible. This is the largest published series to date using daclizumab induction therapy in a renal-sparing regimen.

METHODS

This is a retrospective, nonrandomized study comparing 209 adult liver transplants with daclizumab induction to 115 transplants with no induction.

RESULTS

Patient and graft survival were similar, despite higher pretransplant acuity of illness and older age in the induction group. Acute rejection within the first 6 months occurred less commonly in the induction group (25.4% vs. 39.1%, P=0.01), despite significantly delayed initiation and lower doses of a calcineurin inhibitor. Mycophenolate mofetil was used more commonly in induction patients, but the efficacy of daclizumab in preventing rejection was independent of this. Patients with a pretransplant creatinine concentration 1.5 mg/dL or less had less rejection if they received induction. Renal function worsened in noninduction patients but showed sustained improvement throughout follow-up in induction patients with a pretransplant creatinine concentration greater than 1.5 mg/dL. Induction therapy provided better rejection prophylaxis among those requiring temporary calcineurin inhibitor cessation because of renal dysfunction. The incidences of histologic hepatitis C recurrence and cytomegalovirus infection were similar in each group.

CONCLUSIONS

Liver recipients with and without pretransplant renal dysfunction have less acute rejection with daclizumab induction therapy. This is not associated with an increased risk of over-immunosuppression. Sustained renal improvement in recipients with pretransplant renal dysfunction is possible with daclizumab induction.

Four-year follow-up of a prospective randomized trial of mycophenolate mofetil with cyclosporine microemulsion or tacrolimus following liver transplantation

BACKGROUND

This is a 4-yr follow-up of a trial using mycophenolate mofetil (MMF) induction in orthotopic liver transplantation (OLT). The goal of this study was to evaluate a multidrug approach that would reduce both early and long-term morbidity related to immunosuppression while maintaining an acceptable freedom from rejection.

METHODS

This was a prospective, randomized, intent to treat study designed to compare the primary endpoints of rejection and infection, and secondary endpoints of liver function, renal function, bone marrow function, cardiovascular risk factors, and the recurrence of hepatitis C. Ninety-nine consecutive patients with end stage liver disease who underwent OLT were randomized to receive either cyclosporine microemulsion (N) (50 patients) or tacrolimus (FK) (49 patients) starting on postoperative day 2, with MMF and an identical steroid taper begun preoperatively.

RESULTS

Ninety of 99 patients (N 46, FK 44) completed the 4-yr follow-up. The overall 4-yr patient and graft survivals were 93 and 89%, respectively. There was no significant difference in 4-yr patient (N 96% vs. FK 90%, p = ns) or graft (N, 90% vs. FK, 88%, p = ns) survival between groups. The 4-yr rejection rate was not significantly different in either arm (N = 34%, FK = 24%; p = 0.28). There were no differences in infection rates in either arm. The patients with hepatitis C had no differences in the viral titers or Knodell biopsy scores between groups. However, in the hepatitis C subgroup (37 patients), the FK patients had a significantly lower rejection rate (p = 0.0097) and a significantly lower clinically recurrent hepatitis C rate (p = 0.05) than the N patients. No difference was seen in the percent of patients weaned off of steroids after 4 yr (N 51%, FK 49%). There were no differences in the incidences of diabetes mellitus and hypertension. When renal dysfunction was analyzed, a significant difference in the number of patients whose creatinine had increased twofold since transplant was seen (N 63%, FK 38%, p = 0.04).

CONCLUSIONS

Use of MMF induction and maintenance following OLT in conjunction with either N or FK and an identical steroid taper, resulted in an acceptable long-term incidence of rejection and infection, without an increase in long-term graft or patient morbidity.

Long-term efficacy and safety of mycophenolate mofetil in liver transplant recipients with calcineurin inhibitor-induced renal dysfunction

Long-term survival after orthotopic liver transplantation (OLT) is mainly influenced by adverse events caused by immunosuppression. Several studies have shown the efficacy of mycophenolate mofetil (MMF) in improving calcineurin inhibitor (CI)-induced nephrotoxicity with concomitant reduction or withdrawal of CI. In this prospective study we assessed the long-term effect and safety of MMF. Thirty-two OLT recipients with significant renal impairment due to either cyclosporine A ( n=25) or tacrolimus ( n=7) were enrolled in this study. CIs were reduced stepwise by at least 70%. Mean serum creatinine had decreased from 2.63+/-0.39 to 1.74+/-0.34 mg/dl after 1 month, and this improvement was maintained within a follow-up period of 4.8+/-0.6 (range 3.1-6.0) years, without major immunological or non-immunological side effects. Of all participants, 88% showed a significant reduction, and 41% even a normalization, in their serum creatinine level. In addition, MMF conversion, within 6 months of OLT, appears to be crucial in order to improve or even normalize renal function. This study demonstrates the long-term efficacy and safety of MMF in OLT recipients with CI-induced nephropathy.

Long-term efficacy and safety of mycophenolate mofetil in liver transplant recipients with calcineurin inhibitor-induced renal dysfunction

Long-term survival after orthotopic liver transplantation (OLT) is mainly influenced by adverse events caused by immunosuppression. Several studies have shown the efficacy of mycophenolate mofetil (MMF) in improving calcineurin inhibitor (CI)-induced nephrotoxicity with concomitant reduction or withdrawal of CI. In this prospective study we assessed the long-term effect and safety of MMF. Thirty-two OLT recipients with significant renal impairment due to either cyclosporine A ( n=25) or tacrolimus ( n=7) were enrolled in this study. CIs were reduced stepwise by at least 70%. Mean serum creatinine had decreased from 2.63+/-0.39 to 1.74+/-0.34 mg/dl after 1 month, and this improvement was maintained within a follow-up period of 4.8+/-0.6 (range 3.1-6.0) years, without major immunological or non-immunological side effects. Of all participants, 88% showed a significant reduction, and 41% even a normalization, in their serum creatinine level. In addition, MMF conversion, within 6 months of OLT, appears to be crucial in order to improve or even normalize renal function. This study demonstrates the long-term efficacy and safety of MMF in OLT recipients with CI-induced nephropathy.

Renal function after liver transplantation: calcineurin inhibitor nephrotoxicity

Renal failure, mainly due to calcineurin inhibitor (CNI) nephrotoxicity, is the most common complication following orthotopic liver transplantation (ltx). The aim of this study was to evaluate the incidence and course of renal failure in adult ltx patients. Severe acute renal failure in early postoperative period due to impaired hemodynamics and CNI nephrotoxicity, occurred in 14 patients, 3 of whom required dialysis. The creatinine clearance after ltx showed a tendency to decrease, but there was no statistically significant difference (P >.05) in the change in serum creatinine clearance levels between patients treated with tacrolimus (TAC) versus Cyclosporine (CsA) during the first 2 years of follow-up. Fourteen patients required conversion of their regimen because of CNI nephrotoxicity namely, dose reduction (n = 7) or discontinuation of CNI therapy with the replacement by mycophenolate mofetil (MMF) (n = 5) or SRL (n = 5). Dose reduction or CNI withdrawal significantly improved the creatinine clearance (P <.05) without affecting lives graft function. No episode of acute rejection was observed after conversion. Neither conversion of CsA to TAC nor the reverse maneuver significantly influenced the serum creatinine level (P >.05). Reduction of the CNI dose or CNI discontinuation or replacement with MMF or SRL in patients with stable liver but impaired renal function is safe, resulting in a significant improvement in renal function.

Experimental limb transplantation, part i: identification of an effective tapered triple combination immunosuppressive regime

Limb transplantation was performed across the Brown Norway to Fischer 344 histocompatibility barrier in rats to evaluate the effects of triple combination immunosuppressive therapeutic regimens. Sixty rats were divided into five groups: group I (F344 to F344) isograft controls group II (BN to F344) allograft controls received no immunosuppressive treatment. Groups III and V (BN to F344) received various exposures to tacrolimus (TRL), mycophenolate mofetil (MMF) and prednisolone (Pred) for two weeks: namely, group III: TRL 0.5 mg/kg/d; MMF 10 mg/kg/d; Pred 0.5 mg/kg/d; group IV: TRL 2 mg/kg/d, MMF 15 mg/kg/d, Pred 0.5 mg/kg/d; and group V: TRL 3 mg/kg/d; MMF 20 mg/kg/d; Pred 0.5 mg/kg/d. After 2 weeks, group III and V animals underwent a simultaneous 20% taper of Pred and MMF each further week such that by week 7 the animals were only on TRL. At this time TRL was tapered at the same rate (20% every week) to a maintenance dose of 0.6 mg/kg/d. Evidence of rejection was sought by daily visual observation for swelling, redness, erythema, edema, or skin necrosis. Salvage treatment was used only if rejection occurred after the first 7 weeks, namely, reversing to 100% of the initial TRL dose in that group for 2 weeks with a subsequent taper. Skin and muscle biopsies were obtained from grafted limbs on day 3, 13, 24, 35, and at the endpoint (9 months or uncontrollable rejection). There was no rejection in group I, while all animals showed acute rejection as expected in group II. All group III rats displayed a similar though delayed acute rejection, showing that the regimen was not therapeutic. Rats in group IV displayed the best results, namely, 10 of 12 (83%) with no rejection or side effects at 9 months. Rats in group V displayed numerous, unacceptable side effects due to overtreatment with a 1-month mortality rate of 50%. This study shows that low-dose TRL in combination with MMF and Pred may achieve excellent long-term results of composite tissue transplants. TRL can be used alone as maintenance therapy following an initial loading dose and a tapering period. Rejection is easily reversed by only temporarily increasing the TRL dose.

De novo non-alcoholic fatty liver disease following orthotopic liver transplantation

Non-alcoholic fatty liver disease (NAFLD) is an increasingly recognized clinico-pathologic entity typically associated with obesity, type II diabetes and hyperlipidemia. It has been noted to recur after orthotopic liver transplantation (OLT). We report four patients who developed de novo NAFLD within 3 months of OLT without the typical predisposing factors of diabetes mellitus or obesity. Three of the four patients underwent OLT for hepatitis C-related cirrhosis, and the other for alcoholic cirrhosis. Examination of the liver explants revealed no evidence of steatosis. No surreptitious alcohol use or a drug-induced process could be identified in these patients. Treatment of recurrent hepatitis C infection in one patient with interferon and ribavirin led to sustained suppression of the viral RNA to undetectable levels, but no improvement in histology or liver enzymes. All four patients had histologic evidence of preservation injury on the initial post-OLT biopsies, but the significance of this finding in relationship to the development of NAFLD is unknown. NAFLD can develop without any of the known predisposing conditions after transplantation, and this raises further questions about the pathogenesis of this condition.

Tacrolimus and mycophenolate mofetil provide effective immunosuppression in rat laryngeal transplantation

OBJECTIVES/HYPOTHESIS

Tacrolimus is efficacious in several transplantation settings. Some studies have demonstrated improved results using combination therapy with mycophenolate mofetil. Our primary objective was to evaluate the efficacy and optimal dosing of tacrolimus in preventing rejection, using an established rat model of laryngeal transplantation. Further, the ability of mycophenolate to allow lower dosing of tacrolimus while achieving equivalent immunosuppression was investigated.

STUDY DESIGN

A dosage efficacy study with 10 experimental arms was conducted.

METHODS

Dosage groups were 0.1, 0.2, 0.3, and 0.6 mg/kg tacrolimus alone and 0.1 mg/kg tacrolimus combined with 15 mg/kg mycophenolate mofetil, 0.1 mg/kg tacrolimus combined with 30 mg/kg mycophenolate mofetil, 0.1 mg/kg tacrolimus combined with 40 mg/kg mycophenolate mofetil, 0.2 mg/kg tacrolimus combined with 15 mg/kg mycophenolate mofetil, 0.2 mg/kg tacrolimus combined with 30 mg/kg mycophenolate mofetil (30 d only), and 0.2 mg/kg tacrolimus combined with 40 mg/kg mycophenolate mofetil. Each group contained 8 to 10 rats. Grafts were harvested for histopathological analysis on day 15 or 30 after transplantation. Histopathological appearance of the graft was blindly graded according to an established scale. Dosage groups were compared on rejection score using Wilcoxon's rank sum test and the Jonckheere-Terpstra test for trend.

RESULTS

There was a significant association between increasing dose of tacrolimus and decreasing rejection score at both 15 and 30 days (P <.001). In the groups treated with 0.1 mg/kg T, an increasing dose of mycophenolate was associated with lower rejection scores at both 15 and 30 days (P =.001). In the group treated with 0.2 mg/kg T, there was no evidence that the addition of mycophenolate resulted in lower rejection at 15 days. However, at 30 days, combination therapy with increasing doses of mycophenolate was associated with decreasing rejection score (P =.002).

CONCLUSIONS

Tacrolimus is an effective immunosuppressive agent for laryngeal transplantation. Mycophenolate mofetil allows lower doses of tacrolimus to be used while preserving graft viability in the early post-transplantation period.

Mycophenolatemofetil for immunosuppression after liver transplantation: a follow-up study of 191 patients

BACKGROUND

Mycophenolatemofetil (MMF) combined with calcineurin inhibitors (CNIs) as immunosuppression after orthotopic liver transplantation (OLT) is still under discussion. We retrospectively investigated the immunosuppressive potency of MMF for treatment of steroid-resistant acute rejection (AR) or chronic rejection (CR), chronic graft dysfunction, and CNI-induced toxicity in patients after OLT.

METHODS

Between 1988 and 2001 we performed 1386 OLTs in 1258 patients. Since 1995, 191 patients have received MMF after OLT for steroid-resistant AR or CR, chronic graft dysfunction (115 patients), and CNI-induced toxicity (76 patients). The mean follow-up time was 56 months.

RESULTS

Of 47 patients with steroid-resistant AR, 12 had been treated with OKT3, without resolving the rejection. Overall, bilirubin and transaminases decreased significantly within 2 weeks after the addition of MMF, and liver function normalized in 38 patients. Five of eight patients with CR demonstrated stable liver function after a follow-up of 55+/-8 months; 52 of 60 patients with chronic graft dysfunction improved within 3 months; and 46 of 59 patients with CNI-induced nephrotoxicity improved after MMF treatment and a reduction of CNIs (with a significant decrease in serum creatinine within 2 weeks and an increase of creatinine clearance within 3 months). Clinical symptoms improved in 10 of 12 patients with neurotoxicity and four of five patients with hepatotoxicity. Side effects of MMF, such as gastrointestinal disorders or bone marrow toxicity, occurred in 60 patients (31.4%). The incidence of infections did not increase. Patient survival was 93%, and graft survival was 88.2%.

CONCLUSIONS

MMF is a potent and safe immunosuppressive agent in OLT recipients for rescue therapy in AR, CR, or chronic graft dysfunction and helps to reduce the serious toxic side effects of CNIs.

Therapy for acute rejection in pediatric organ transplant recipients

Despite the availability of potent immunosuppressive drugs, rejection after organ transplantation in children remains a serious concern, and may lead to significant morbidity, graft loss, and death of the patient. Acute graft rejection in pediatric recipients is first treated with methylprednisolone pulses, followed by progressive taper of corticosteroid doses. After control of the rejection episode, baseline immunosuppression has to be adjusted and closely monitored since rejection (especially late episodes, occurring more than 6 months after transplantation) may be due to a lack of compliance or sub-therapeutic drug concentrations. The management of corticosteroid resistant rejection is not standardized, and depends on the transplanted organ and previous immunosuppressive regimen. In patients experiencing corticosteroid resistant acute rejection while on a cyclosporine-based immunosuppressive regimen, cyclosporine is generally changed to tacrolimus. In case of tacrolimus-based immunosuppression, tacrolimus blood levels may be increased, and/or mycophenolate mofetil (which nowadays tends to replace azathioprine) or sirolimus may be added, although pharmacodynamic data and clinical studies with these agents are still scarce in pediatric recipients. The use of antithymocyte globulins or monoclonal anti-CD3 antibodies, muromonab CD3 (OKT3) is hampered by numerous adverse effects, including a significant risk of over-immunosuppression. These therapies are nowadays indicated in very selected cases. Other treatments such as plasmapheresis and high dose immunoglobulins may be useful in difficult cases. In patients with refractory rejection despite therapeutic escalation, the risks of over-immunosuppression, including opportunistic infections and malignancies (especially the Epstein-Barr virus related post-transplant lymphoproliferative disease) have to be balanced with the consequences of graft loss due to rejection. Detransplantation or retransplantation may, in some instances, be preferable to severe infectious or tumoral complications.

Calcineurin inhibitor-induced chronic nephrotoxicity in liver transplant patients is reversible using rapamycin as the primary immunosuppressive agent

The purpose of this study was to determine whether calcineurin inhibitor (CNI)-induced chronic nephrotoxicity in liver transplant patients is reversible by replacement of the CNI with rapamycin as the primary immunosuppressive agent. CNIs, while providing potent immunosuppression for liver transplant patients, exhibit nephrotoxicity as a major side-effect. Whereas acute CNI-induced nephrotoxicity is reversible by withdrawal of the CNI, chronic nephrotoxicity due to CNIs is a progressive process thought to be irreversible. Eight liver transplant patients with CNI-induced chronic nephrotoxicity were converted to rapamycin as the primary immunosuppressive agent. The CNI was either discontinued (four patients) or the dosage lowered to maintain a subtherapeutic level (four patients). Renal function as assessed by serum creatinine was measured before and after conversion to rapamycin. Two patients progressed to dialysis dependence following conversion to rapamycin. These two patients had been on CNIs for a mean of 112 months (range 93-131 months) prior to conversion to rapamycin. Five patients experienced improvement in renal function. These patients had been on calcineurin inhibitors for a mean of 60 months (range 42-75 months) prior to conversion. One patient with chronic nephrolithiasis as a contributing factor to his renal dysfunction has progressed to dialysis dependence despite conversion to rapamycin following exposure to a CNI for 24 months. In the five patients with improved renal function, serum creatinine levels decreased significantly (2.4 +/- 0.3 mg/dL to 1.5 +/- 0.1 mg/dL, p < 0.05) by a mean of 7.2 months (range 5-10 months) after conversion from CNI to rapamycin-based immunosuppression. Liver function remained stable after conversion to rapamycin. CNI-induced chronic nephrotoxicity can be reversed upon withdrawal of the CNI. Rapamycin is an effective replacement agent as primary immunosuppressive therapy following withdrawal of CNIs in liver transplant patients with CNI-induced chronic nephrotoxicity.

Single-agent immunosuppression after liver transplantation: what is possible?

Orthotopic liver transplantation is a life saving and life enhancing procedure. The development of immunosuppressive drugs has contributed to the high rate of success in terms of both patient and graft survival. However, the considerable adverse effects of these therapies are affecting long-term outcomes of transplant recipients. Complications related to immunosuppression are responsible for the majority of deaths in patients surviving more than 1 year. Therefore, the search for an optimal immunosuppressive regimen has become of paramount importance. The liver has proved to be an 'immunologically privileged' organ, capable in several animal models to be accepted as an allograft without any intervention on the immune system of the recipient. In some human liver allografts acceptance of the new organ is recognised after withdrawal of immunosuppressants, but prior identification of such individuals is not yet possible, thus negating this management option. Graft-recipient interaction is peculiar in liver transplantation: acute cellular rejection does not always need to be treated, and if it is not severe, appears to be associated with a better survival of both patient and graft. In the last decade there has been an evolution of immunosuppressive protocols, driven by empirical observation and a deeper understanding of immunological events after transplant. However, most modifications have been made because of the necessity to reduce long-term drug related morbidity and mortality. Withdrawal of corticosteroids has proven to be safely achievable in most patients, with no deleterious effects on patient or graft survival but with a great benefit in terms of reduction of incidence of metabolic and cardiovascular complications. Long-term 'steroid-free' regimens are therefore now widely used. Patients with stable graft function can be easily maintained using a single drug usually after 6 or 12 months and usually with a calcineurin inhibitor. The more evolved step of using monotherapy ab initio has also proven to be effective in a few studies and needs to be explored further. In the future new strategies will be designed to help the development of tolerance of the allograft, selectively stimulating instead of suppressing the immune reaction of the recipient.

The impact of novel immunosuppressive agents on infections in organ transplant recipients and the interactions of these agents with antimicrobials

Several of the new immunosuppressive agents that are used to treat transplant recipients possess in vitro activity against specific pathogens, enhance the activity of antimicrobial agents, or have unique drug interactions with antimicrobial agents. Mycophenolate mofetil may have a protective effect against Pneumocystis carinii; it also enhances the activity of ganciclovir and has strong antiviral activity against human immunodeficiency virus type 1. High doses of mycophenolate mofetil have been associated with a higher frequency of tissue-invasive cytomegalovirus disease but not with asymptomatic cytomegalovirus infection. Rapamycin exhibits potent in vitro fungicidal activity against Cryptococcus neoformans and several pathogenic fungi in transplant recipients; however, it is not known whether its immunosuppressive effect in organ transplant recipients outweighs its antifungal activity. Recognition of the unique characteristics of these agents and the evolving spectrum of opportunistic infections has implications for the differential diagnosis, management, and prophylaxis of infections in organ transplant recipients in the modern immunosuppressive era.

Options for induction immunosuppression in liver transplant recipients

Immunosuppression administered in the early postoperative period following liver transplantation plays a crucial role in the survival of the graft and the patient. The introduction of cyclosporin was an important landmark in transplantation, and to this day, calcineurin inhibitors form the basis of most induction immunosuppression regimens. New drugs are being developed which are more specifically targeted to prevention of rejection, and multiple drug combinations have been proposed as a means of reducing the adverse effects of individual drugs. Azathioprine and the newer antimetabolite mycophenolate mofetil have been added to calcineurin inhibitor-based regimens with varying amounts of success. Antibody induction has evolved as a potent form of immunosuppression as well as a means of avoiding certain adverse effects, particularly nephrotoxicity. The numerous adverse effects encountered with polyclonal preparations have been reduced with the development of more specific monoclonal antibodies such as muromonab CD3 (OKT3) or interleukin (IL)-2 receptor (IL-2R) antagonists. The anti-IL-2R antibody preparations basiliximab and daclizumab have shown excellent early results due to their potent yet highly targeted immunosuppressive effect and minimal adverse effects. Further study is needed to determine the most appropriate dosage, timing and patient population for these new drugs in the setting of liver transplantation. Although a number of different induction regimens have been described, no single protocol is suitable for all liver transplant recipients. Rather, certain regimens have advantages that could favour their use in a specific subgroup of patients. A number of clinical trials are underway to identify new, more specific drugs and combinations which could be useful in induction immunosuppression.

Comparative efficacy of mycophenolate sodium (MPS) and mycophenolate mofetil (MMF) with and without cyclosporine in rat transplantation models

BACKGROUND

ERL is the enteric-coated sodium salt of mycophenolic acid, presently in clinical development. The drug substance mycophenolate sodium (MPS) was evaluated in rat transplantation models and compared with mycophenolate mofetil (MMF) for therapeutic window and synergy with cyclosporine (CsA).

METHODS

Allotransplantation was performed in the Dark Agouti-to-Lewis (DA-to-Lewis; kidney, heart, and aorta) and Brown Norway-to-Lewis (BN-to-Lewis; kidney) strain combinations, and hamster heart xenotransplantation was performed in athymic and euthymic Lewis rats. The compounds were administered daily orally, starting the day of transplantation.

RESULTS

In kidney and heart transplantation the minimal efficacious dose of CsA was 5.0 mg/kg/d. For MPS this dose was 10 mg/kg/d in BN-to-Lewis kidney transplantation, 20 mg/kg/d in DA-to-Lewis heart transplantation, and 10 mg/kg/d in hamster-to-athymic rat heart transplantation. At these doses the first signs of adverse effects were evident, indicating a narrow therapeutic window. No window was established for MMF in these models or for MPS in DA-to-Lewis kidney transplantation. There was no potential synergy between CsA and MPS or MMF regarding efficacy, but fewer side effects were noted in efficacious combinations, in particular for MPS. In aorta transplantation, MPS and MMF dose-dependently inhibited intima thickening. The combination of 20 mg/kg/d MPS and 10 mg/kg/d CsA gave long-term survival of hamster-to-rat xenografts.

CONCLUSIONS

Despite the overall comparable efficacy and narrow therapeutic window of MPS and MMF when given alone, MPS apparently is better tolerated than MMF in some of the transplant models. The combination of these agents with CsA allows fine-tuning between optimal immunosuppression and adverse side effects.