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Abstract

  1. Top of page
  2. Abstract
  3. METHODS
  4. RESULTS
  5. DISCUSSION
  6. REFERENCES

The appropriate time point for starting immunosuppressive treatment with calcineurin inhibitors after orthotopic liver transplantation (OLT) has been a subject of debate. The aim of the study was to analyze the effects of anti-thymocyte globulin (ATG) induction therapy on rejection, renal function, infection, tumor rate, and survival. We retrospectively analyzed 391 patients after OLT who had either received calcineurin inhibitors immediately after OLT (n = 129) or after an initial short-term Thymoglobulin induction therapy (n = 262). The 1-year acute rejection rate was 14.5% vs. 31.8% in favor of ATG (P = 0.0008). Rejection grades and the need for treatment also differed significantly (7.3% vs. 23.3%; P = 0.001). Serum creatinine at transplantation was similar in both groups (1.14 mg/dL vs.1.18 mg/dL; P = NS). Postoperative hemofiltration was less frequently seen after induction therapy (P < 0.05). Reduced renal function at 1 year was commonly observed, but serum creatinine (1.26 mg/dL vs. 1.37mg/dL; P = 0.015) and glomerular filtration rate (81 mL/min vs. 75 mL/min; P = 0.02) were far better in the ATG group. Undesired side effects occurred at a similar rate in both groups. Five-year patient survival was also similar in the 2 groups (70.1% and 74.3%; P > 0.05). Short-term ATG induction therapy with delayed administration of calcineurin inhibitors led to a more favorable rejection rate and an improved clinical course in case of a rejection episode. It has beneficial effects on renal function immediately after OLT as well as later, and no additional harmful effects. Liver Transpl 13:1039–1044, 2007. © 2007 AASLD.

It took nearly 20 years for orthotopic liver transplantation (OLT) to develop into a widely used standard procedure for patients with end-stage liver disease. One of the essential aspects of this development was the introduction of cyclosporine A (CyA) in clinical immunosuppression. CyA led to far lower rejection rates than those achieved with any other drug known at the time. Several immunosuppressive agents have been developed since and are used in various regimens with calcineurin inhibitors (e.g., CyA and tacrolimus). Immunosuppressants are a fundamental aspect of nearly all treatment protocols for OLT.1 However, for more then 40 years, debate has existed regarding when immunosuppression in OLT should be initiated and what treatment should be used. The spectrum ranges from nearly all kinds of T cell–depleting antibodies and interleukin-2 receptor antibodies to simply providing no specific induction therapy, and the use of the same regimen when maintenance therapy is started.2–4

The purpose of all immunosuppressive regimens is to achieve low rejection rates on the one hand and a favorable side effect profile on the other. To accomplish this goal, it is important to decide whether induction therapy should be administered, and if so, which drugs should be administered and in what manner. A combination of different drugs and the sequence of their use might be the key to successful clinical immunosuppression.5 The aim of the present study was to analyze the effects of a short-term anti-thymocyte globulin (ATG) induction therapy combined with delayed administration of calcineurin inhibitors on rejection rates, infection, renal function, and survival compared with a classical regimen without induction therapy and immediate use of calcineurin inhibitors and corticosteroids.

METHODS

  1. Top of page
  2. Abstract
  3. METHODS
  4. RESULTS
  5. DISCUSSION
  6. REFERENCES

In a retrospective study, we analyzed 391 adult patients who had undergone their first OLT between 1997 and 2004. The patients had either received immunosuppression without induction therapy and calcineurin inhibitors immediately after surgery (group 1, n = 129) or a short-term Thymoglobulin induction therapy combined with delayed administration of calcineurin inhibitors (group 2, n = 262). The induction-free protocol was used as part of our center's participation in a multicenter study (European Liver Transplant Tacrolimus Vs. Cyclosporin Study Group, Study FG-506-01-23); the latter regimen is the standard treatment at our center. Therefore, the latter group served as matched controls.

Starting at 6 hours after transplantation, group 2 received rabbit anti-human thymocyte immunoglobulin (Thymoglobulin, Merieux, Lyon, France) at a dose of 2.5 mg/kg body weight administered intravenously as a daily infusion over a 6-hour period. This induction therapy was continued for 3 days. Starting on the evening of the third day after ATG administration, CyA (Neoral, Novartis Pharma, Basel, Switzerland) was administered orally at a dose of 8 mg/kg per day in 2 doses, and the dosage was adjusted to obtain a trough whole blood target level of 100–150 ng/mL. In group 1, the patients received, immediately after OLT, either CyA in the same manner and dosage as in group 2, or tacrolimus (Prograf, Fujisawa, Germany) at a dose of 0.15 mg/kg per day orally in 2 doses; the dose was adjusted to achieve a trough whole blood target level of 10–12 ng/mL. The target levels, administration, and monitoring of calcineurin inhibitors were identical for patients who took part in studies and those who did not.

All patients received an intravenous bolus of 40 mg dexamethasone, which was provided intraoperatively and tapered to 4 mg by day 5. Twenty milligrams of prednisolone was administered orally thereafter. The dosage was decreased by 5 mg on a monthly basis to a dose of 5 mg per day. After 3–6 months, corticosteroids were usually withdrawn from patients without cholestatic or autoimmune liver disease, so long-term maintenance immunosuppression consisted of calcineurin inhibitor monotherapy.

All patients received an antiviral prophylaxis at a daily dose of 1 g acyclovir (Zovirax, GlaxoSmithKline S.p.A, Parma, Italy) in 4 equal doses. It was administered intravenously for the first week after OLT. No antibiotic or fungal prophylaxis was provided.

During hospitalization, complete laboratory investigations were performed daily. Patients underwent daily ultrasound examination until the fifth postoperative day. Additionally, they had weekly screenings for cytomegalovirus, herpes simplex, Epstein-Barr virus, varicella zoster, and human immunodeficiency virus by enzyme-linked immunosorbent assay and screening for hepatitis A, B, and C virus by chemoluminescent microparticle immunoassay. This screening was repeated during outpatient follow-up.

For the assessment of postoperative renal function, we used serum creatinine levels and the glomerular filtration rate (GFR) calculated by the Modification of Diet in Renal Disease method6 at the time of transplantation and 1 year later. Additionally, we calculated the renal function ratio (serum creatinine at 1 year:serum creatinine at transplantation; GFR at 1 year:GFR at transplantation) as an intrapersonal control of the individual development of kidney function. Furthermore, we determined the total number of patients who had severe renal failure, which was defined as the need for hemofiltration on more then 2 consecutive days during the postoperative stay in the intensive care unit.

The outpatient follow-up investigations were usually performed every week during the first month after discharge, twice a month during the second and third months, once a month during the next 3 months, and every 2 or 3 months thereafter, regardless of the duration of the observation period after transplantation. Patients were free to visit the doctor at any time in the event of a specific problem. A complete laboratory investigation was performed at each visit. All patients were available for follow-up. The diagnosis of acute rejection had to be proven by histological investigation during the hospital stay as well as during follow-up. A fine-needle biopsy was performed in the event of ambiguous fever and indisposition, an increase in bilirubin and transaminase levels with more than a 10% increase in liver parameters on more than 2 consecutive days, or an excessive increase at 2 controls. Rejection was categorized in accordance with the BANFF criteria.7

All results are expressed as mean ± SD. Statistical analyses were performed by the χ2 test for differences in categorical data and the t test for continuous variables. Patient and graft survival curves and freedom from acute rejection episodes were calculated with the Kaplan-Meier method. A probability value of P < 0.05 was considered to be statistically significant.

RESULTS

  1. Top of page
  2. Abstract
  3. METHODS
  4. RESULTS
  5. DISCUSSION
  6. REFERENCES

Preliminary analyses showed no difference in the characteristics or outcome between patients receiving cyclosporine or tacrolimus (Table 1). Therefore, all of these were assigned to group 1 for further calculation, which resulted in a 1:2 ratio between group 1 and group 2. The duration of follow-up in the group without induction therapy was 51 ± 33 months, while patients in the 3-day ATG group were followed for 37 ± 22 months (P < 0.05). The demographic data showed no statistically significant difference; the distribution of primary liver disease was also similar in the 2 groups (Table 2).

Table 1. Patient Characteristics and Outcome for CyA Vs. FK 506
CharacteristicCyA (n = 39)FK 506 (n = 90)P value
  • Abbreviations: CyA, cyclosporine A; OLT, orthotopic liver transplantation; GFR, glomerular filtration rate.

  • *

    Data refer to patients alive at 1 year (34 patients in CyA group vs. 78 patients in group FK 506).

Gender (M:F)74:2666:34NS
Recipient age (yr)49 ± 1152 ± 9NS
Underlying disease   
 Alcoholic cirrhosis38%29%NS
 Virus-induced cirrhosis15%21%NS
 Hepatocellular carcinoma30%24%NS
 Other cirrhosis17%26%NS
Median follow-up median (months)50.150.8NS
Acute rejection at 1 year33%31%NS
Infection rate55%53%NS
Hemofiltration rate23%26%NS
Serum creatinine (mg/dL) (mean ± SD)   
 At OLT1.15 ± 0.421.15 ± 0.46NS
 After 1 year*1.37 ± 0.461.36 ± 0.56NS
GFR (mL/min) (mean ± SD)   
 At OLT97 ± 3794 ± 27NS
 After 1 year*77 ± 2376 ± 20NS
Table 2. Patient Characteristics
CharacteristicGroup 1 (n = 129)Group 2 (n = 262)P value
Sex (M:F)68:3271:29NS
Recipient age (yr) (mean ± SD)51.2 ± 1051.1 ± 10NS
Underlying disease   
 Alcoholic cirrhosis32%36%NS
 Virus-induced cirrhosis20%25%NS
 Hepatocellular carcinoma26%18%NS
 Cholestatic disease5%9%NS
 Other cirrhosis17%12%NS

The overall 1-year acute rejection rate was 14.5% (n = 38) in the group that received ATG induction therapy and 31.8% (n = 41) in the group that did not (P = 0.0008; Fig. 1). The proportion of severe acute rejections was not equally distributed (group 1, 12%, vs. group 2, 3%), but the difference was not statistically significant. The clinical presentation of acute rejection episodes differed significantly: 23.3% of patients (n = 30) required treatment in group 1, whereas 7.3% of patients (n = 19) required treatment in group 2 (P = 0.001). Furthermore, 9.3% (n = 12) of rejections in the cohort without induction therapy required ATG as rescue therapy to treat severe rejection (n = 8) or corticosteroid-resistant rejection episodes (n = 4). On the other hand, no patient required repetitive administration of ATG after induction therapy, and no corticosteroid-resistant rejection was observed. This demonstrates the significant superiority of the induction protocol with respect to the need of treatment for acute rejection episodes, particularly the need for Thymoglobulin (P = 0.001). Nearly the same number of patients were successfully treated with corticosteroid bolus therapy (32% group 1 vs. 34% group 2, P > 0.5). The number of patients whose maintenance immunosuppression was merely adjusted did not differ significantly in the 2 groups (18% in group 1 vs. 10% in group 2, P = 0.5). Furthermore, the rate of chronic rejection was also similar: 3.1% in group 1 vs. 3.8% in group 2. A late modification of the immunosuppressive regimen after more than a mean of 2 years by introducing rapamycin instead of calcineurin inhibitors as a result of impaired renal function was done in 11% of patients (n = 14) after immediate calcineurin inhibitors use and 16% of patients (n = 41; P = NS) after ATG induction therapy.

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Figure 1. Acute rejection.

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Serum creatinine at transplantation was 1.14 ± 0.45 in group 1 and 1.18 ± 0.55 in group 2; the difference was not statistically significant. The difference in GFR levels also did not achieve statistical significance. A reduction of renal function at 1 year was observed in both groups, but serum creatinine, GFR, and the renal function ratio were far better in group 2 (Table 3). To avoid bias in the assessment of renal function parameters after 1 year because more patients received perioperative hemofiltration in group 1, we performed a subanalysis that excluded patients who underwent hemofiltration in either group. At 1 year after OLT, serum creatinine levels were 1.24 ± 0.3 mg/dL vs. 1.33 ± 0.5 mg/dL (P = 0.03), while GFR was 83 ± 23 mL/min vs. 78 ± 22 mL/min (P = 0.05), with both parameters in favor of patients who had undergone induction therapy and delayed use of calcineurin inhibitors.

Table 3. Renal Function
Renal parameterGroup 1 (n = 129)Group 2 (n = 262)P value
  • Abbreviations: OLT, orthotopic liver transplantation; GFR, glomerular filtration rate.

  • *

    Data refer to patients alive at 1 year (112 in group 1 vs. 220 in group 2).

Hemofiltration rate, n (%)32 (25%)43 (16%)0.046
Serum creatinine (mg/mL), (mean ± SD)   
 At OLT1.14 ± 0.451.18 ± 0.550.199
 After 1 year*1.37 ± 0.531.26 ± 0.340.015
GFR (mL/min), (mean ± SD)   
 At OLT94 ± 3096 ± 480.336
 After 1 year*75 ± 2181 ± 230.020
Serum creatinine ratio, (mean ± SD)   
Creatinine 1 year*/creatinine OLT1.31 ± 0.601.18 ± 0.470.021
GFR ratio, (mean ± SD)   
GFR 1 year*/GFR OLT0.86 ± 0.340.96 ± 0.470.019

In the perioperative phase, 50.3% (n = 70) of patients in group 1 had 1 or more bacterial and/or fungal infection, whereas the infection rate in group 2 was 41.6% (n = 109; P = 0.2). During the observation period, the rate of viral infection was 7.3% (n = 19) after ATG induction therapy and 7.0% (n = 9) after induction-free immunosuppression (P > 0.5).

Five-year patient survival was 70.1% in group 1 and 74.3% in group 2 (Fig. 2). There was no statistically significant difference in graft survival at the same time point: 68.0% for transplant recipients immediately treated with calcineurin inhibitors and 71.8% for those who received induction therapy. The major risk factor for mortality was postoperative infection, which led to death in 39.5% of patients in group 1 and 35.0% of patients in group 2. The rates of tumor recurrence and de novo malignancies were 5.4% vs. 1.9% and 2.3% vs. 0.8%, respectively; the frequency was a little higher in group 1, but the difference was not statistically significant. The rate of posttransplantation lymphoproliferative disease was increased after ATG induction therapy compared with the induction-free protocol (2.3% vs. 0.9%) but did not reach statistical significance. The same was true for the distribution of other causes of death during the follow-up period (Table 4).

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Figure 2. Patient survival.

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Table 4. Causes of Death During Follow-up
Cause of deathGroup 1 (n = 129)Group 2 (n = 292)P value
Primary nonfunction3 (2.3%)4 (1.5%)NS
Vascular complication4 (3.1%)9 (3.4%)NS
Acute rejection2 (0.8%)1 (0.8%)NS
Sepsis17 (13.2%)21 (8.0%)NS
Hepatitis recurrence2 (1.6%)5 (1.8%)NS
Tumor recurrence7 (5.4%)5 (1.9%)NS
De novo malignancies3 (2.3%)2 (0.8%)NS
Other6 (4.7%)12 (4.6%)NS

DISCUSSION

  1. Top of page
  2. Abstract
  3. METHODS
  4. RESULTS
  5. DISCUSSION
  6. REFERENCES

The use of induction therapy in liver transplantation is not as common as in other solid organ transplantations. Nevertheless, about 20% of liver transplant recipients receive induction therapy. ATG is viewed with caution because it is liable to cause severe side effects and to promote perioperative complications, such as infection.8, 9 However, because the adequacy of this drug has been proven in several studies, it is better to find an appropriate regimen for its application than to altogether abandon its use in the clinical setting.10, 11

To gain more information on this subject, we analyzed patients who received no ATG induction therapy for several reasons, such as participation in immunosuppressive studies, and compared them with matched patients who received induction therapy and subsequently calcineurin inhibitors. The demographics of the 2 groups did not differ greatly. The difference in the duration of follow-up was due to the disproportionately large number of patients in group 1 at the beginning of the observation period. This imbalance was compensated by the 2:1 ratio in favor of group 2, which permitted twice the number of observations in the first year after OLT (i.e., the time period of specific interest).

The acute rejection rate was far higher in the group that received no ATG. Published rates of acute rejection after induction therapy within the first 6 months and 1 year after transplantation vary widely, from 6% to 37%.5, 12 However, independent of the results of induction-free immunosuppressive protocols in different centers, the additional use of ATG improved the inner-center rejection rates.10, 13 Worthy of note is the fact that despite the nearly identical distribution of rejections in the BANFF classification, the episodes differed greatly in terms of their clinical presentation. Notably, 24% of patients in group 1 and 50% in group 2 needed no specific therapy, even in low-grade rejection episodes. This highly relevant difference in the posttreatment clinical course is further underlined by the fact that the frequency of corticosteroid-resistant rejection and the need for ATG rescue therapy were clearly in favor of the induction protocol. In contrast, chronic rejection was of no importance during the observation period and did not differ between the groups.

Kidney function at the time of OLT was similar in the 2 groups and declined greatly within the first year after OLT. However, renal parameters were better in patients who had received induction therapy. Early events such as the hemodialysis rate and late renal function tests such as GFR at 1 year are positively influenced by this immunosuppressive regimen. The advantage of the delayed use of calcineurin inhibitors, as shown in other studies, was clearly confirmed by our findings.14–16 However, this benefit may not have been entirely due to the later administration of calcineurin inhibitors, which are known to be nephrotoxic, particularly immediately after transplantation—a time when the kidneys are highly susceptible to harmful substances. Thymoglobulin itself appears to prevent early renal impairment by suppressing the release of proinflammatory mediators that play an important role in the development acute renal failure.17, 18 Thus, the kidney-protective effects of an immunosuppressive protocol of this type may be attributed to a combination of several factors.

Perioperative infection rates revealed no specific regimen to be better in terms of lower septic complications or improved survival. Infection is an independent risk factor for survival, regardless of the immunosuppressive regimen used. The overall infection rate was comparable to those registered at other centers.16, 19

Five-year patient and graft survival were favorable in both groups and showed no statistically significant difference during follow-up. The differences in the rates of de novo malignancies and tumor recurrences were not statistically significant between patients who received ATG and those who did not. In contrast to some studies in which ATG was administered for a prolonged period of time,9, 20 malignant tumors were not found particularly frequently in our investigation.

In conclusion, our results show that 3-day ATG induction therapy with delayed use of calcineurin inhibitors is a good option. Compared with an induction-free protocol, this regimen provides an excellent rejection rate and a far better clinical course for patients who experience acute rejection. A 3-day ATG induction therapy with subsequent administration of calcineurin inhibitors has beneficial effects on renal function immediately after OLT as well as later on, while causing no further adverse effects. Tailored treatment consisting of a combination of different drugs administered sequentially appears to be one of the key aspects of a successful immunosuppressive regimen. Our results demonstrate the superiority of a specific treatment regiment in terms of simple rejection rates, as well as underline the importance of other criteria in the assessment of the efficacy of immunosuppressive protocol.

REFERENCES

  1. Top of page
  2. Abstract
  3. METHODS
  4. RESULTS
  5. DISCUSSION
  6. REFERENCES
  • 1
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  • 2
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    Guitard J, Cointault O, Kamar N, Muscari F, Lavayssiere L, Suc B, et al. Acute renal failure following liver transplantation with induction therapy. Clin Nephrol 2006; 65: 103112.
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    Tchervenkov JI, Tzimas GN, Cantarovich M, Barkun JS, Metrakos P. The impact of thymoglobulin on renal function and calcineurin inhibitor initiation in recipients of orthotopic liver transplant: a retrospective analysis of 298 consecutive patients. Transplant Proc 2004; 36: 17471752.
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    Mueller TF. Thymoglobulin: an immunologic overview. Curr Opin Organ Transpl 2003; 4: 305512.
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    Goggins WC, Pascual MA, Powelson JA, Magee C, Tolkoff-Rubin N, Farrell ML, et al. A prospective, randomized, clinical trial of intraoperative versus postoperative thymoglobulin in adult cadaveric renal transplant recipients. Transplantation 2003 15; 76: 798802.
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    Neuhaus P, Klupp J, Langrehr JM, Neumann U, Gebhardt A, Pratschke J, et al. Quadruple tacrolimus-based induction therapy including azathioprine and ALG does not significantly improve outcome after liver transplantation when compared with standard induction with tacrolimus and steroids: results of a prospective, randomized trial. Transplantation 2000; 69: 23432353.
  • 20
    Jonas S, Rayes N, Neumann U, Neuhaus R, Bechstein WO, Guckelberger O, et al. De novo malignancies after liver transplantation using tacrolimus-based protocols or cyclosporine-based quadruple immunosuppression with an interleukin-2 receptor antibody or antithymocyte globulin. Cancer 1997; 80: 11411150.