Midterm results of a prospective randomized comparison of two different rabbit-antithymocyte globulin induction therapies after heart transplantation

Midterm Results of a Prospective Randomized Comparison of Two Different Rabbit-Antithymocyte Globulin Induction Therapies After Heart Transplantation L.S. De Santo, A. Della Corte, G. Romano, C. Amarelli, F. Onorati, M. Torella, M. De Feo, C. Marra, C. Maiello, B. Giannolo, R. Casillo, E. Ragone, M. Grimaldi, R. Utili, and M. Cotrufo ABSTRACT This prospective randomized study compared the effects in heart transplant recipients of thymoglobulin and ATG, two rabbit polyclonal antithymocyte antibodies available for induction therapy. Among 40 patients (29 men and 11 women, mean age: 40.7 ⫾ 14 years) undergoing orthotopic heart transplantation, 20 were randomly allocated to receive induction with thymoglobulin (group A) and 20 to ATG-fresenius (group B). Comparisons between the two groups included early posttransplant (6 months) incidence of acute rejection episodes (grade ⱖ 1B), bouts of steroid-resistant rejection, time to first rejection, survival, graft atherosclerosis, infections, and malignancies. The study groups displayed similar preoperative and demographic variables. No significant difference was found with regard to actuarial survival (P ⫽ .98), freedom from rejection (P ⫽ .68), number of early rejections ⬎ 1B (P ⫽ .67), mean time to first early cardiac rejection (P ⫽ .13), number of steroid-resistant rejections (P ⫽ .69). Cytomegalovirus reactivations were more frequent among group A (65%) than group B (30%; P ⫽ .028). New infections due to cytomegalovirus occurred only in group A (four patients; 20%; P ⫽ .05). No cases of malignancies were observed at a mean follow-up of 32.8 ⫾ 8.9 months. Although thymoglobulin and ATG showed equivalent efficacy for rejection prevention, they have different immunological properties. In particular, thymoglobulin seems to be associated with a significantly higher incidence of cytomegalovirus disease/reactivation.

C

ARDIAC TRANSPLANTATION is the only therapeutic modality to achieve long-term survival for patients with end-stage heart disease.1 Several advances in posttransplant management have occurred during the last two decades, among them changes in immunosuppressive therapy, leading to significantly better long-term outcomes and widening of eligibility criteria.2 In addition to the development of new maintenance immunosuppressive agents for posttransplant therapy, such as tacrolimus and mycophenolate mofetil, different types of mono- or polyclonal antibody preparations have been introduced for perioperative prophylaxis to delay administration of cyclosporine, thus avoiding acute nephrotoxicity during the immediate postoperative period, which is often characterized by hemodynamic instability.3 Large series have shown the efficacy of this strategy to achieve low rates of early acute rejection episodes4,5 through mechanisms of complement-dependent cytolysis of the recipient lympho© 2004 by Elsevier Inc. All rights reserved. 360 Park Avenue South, New York, NY 10010-1710 Transplantation Proceedings, 36, 631– 637 (2004)

cytes, of opsonization with destruction of immune cells by the reticuloendothelial system, or by induction of apoptosis following binding to surface antigens.6,7 Among the polyclonal antibodies available for the clinical use are thymoglobulin (IMTIX-SangStat, Lyon, France) and ATG-Fresenius (Fresenius AG, Bad Homburg, Germany). Thymoglobulin, an injectable solution of purified IgG immunoglobulins with pronounced lymphocytotoxic antibody activity, is obtained by hyperimmunization of rabbits with human thymocytes. ATG-Fresenius, which is produced in From the Department of Cardio-Thoracic and Respiratory Sciences (L.S.D.S., A.D.C., G.R., C.A., F.O., M.T., M.D.F., C.M., C.M., B.G., M.C.) and Chair of Internal Medicine (R.C., E.R., M.G., R.U.), Service of Infectivological and Transplant Medicine, Second University of Naples, V Monaldi Hospital, Naples, Italy. Address reprint requests to Luca Salvatore De Santo, Viale Colli Aminei 491, 80129 Naples, Italy. E-mail: luca. [email protected] 0041-1345/04/$–see front matter doi:10.1016/j.transproceed.2004.02.053 631

632

rabbits hyperimmunization with an immortalized cellular line (Jurkat), contains various immunoglobulin fractions with high antilymphocyte activity. The efficacy of those two preparations has been separately assessed in several clinical studies,8 –10 which have differed with respect to the daily dosage, the duration of the induction, and the mode of administration (bolus or continuous infusion, intravenous or intramuscular). This prospective randomized study was devised to compare the immunosuppressive effects of these two rabbit polyclonal antibody preparations, using comparable administration schemes in primary cardiac transplant recipients. PATIENTS AND METHODS Study Design This trial was designed as a single-center open-label prospective study on rabbit-antithymocyte globulin induction therapy for recipients of primary heart transplants. Male or female patients undergoing first heart transplants were enrolled after giving written informed consent. The following conditions caused exclusion from the study: recipient of a second transplant; previous malignancy; pregnancy or female patient of childbearing potential not using a medically approved, effective form of contraception during the study; recent history of systemic infection, severe diarrhea, active peptic ulcer or gastro-intestinal diseases interfering with the absorption of oral immunosuppressive agents; previous treatment with antilymphocyte globulin or monoclonal antibodies; history of drug addiction, psychiatric disorder, or behavioral attitude interfering with compliance to therapy; recent enrollment in other trials of immunosuppressive drugs.

Study Population Between January 1998, and December 1999, 40 patients (29 men and 11 women), ranging between 13 and 53 years of age (mean: 40.7 ⫾ 14) underwent orthotopic heart transplantation. Patients undergoing transplantation were randomly allocated to group A, in which induction was performed with thymoglobulin (IMTIX-SangStat, Lyon, France) or group B, ATG-fresenius (Fresenius AG, Bad Homburg, Germany). Treatment assignment was recorded on cards that were placed in serially numbered sealed envelopes. The ordering of the cards within the envelopes was determined from a table of random numbers. Envelopes were opened on the day of transplantation after recipient selection. All the procedures were performed by the same group of surgeons. Graft procurement included implied cold cardioplegic arrest and preservation used Celsior solution and topical hypothermic storage. The biatrial technique described by Lower and Shumway11 was the standard procedure for allograft implantation.

Immunosuppressive Protocol As regards induction therapy, group A patients received thymoglobulin at a daily dose of 2.5 mg/kg for the first 5 postoperative days, while group B ATG-fresenius, at 2.5 mg/kg/d for 7 days. Continuous infusion of antibody via a central venous catheter was initiated upon admission to the intensive care unit. Dosage and treatment periods were performed in accordance with manufacturer’s recommendations. Onset of anaphylaxis or leukopenia (⬍2000/ mm3) or thrombocytopenia (⬍50000/mm3) mandated treatment discontinuation. Immunosuppressive therapy with steroids, aza-

DE SANTO, DELLA CORTE, ROMANO ET AL thioprine, and cyclosporine (Neoral) was the standard protocol. Intravenous methylprednisolone administration was initiated at a dosage of 500 mg during the operation, followed in the postoperative period by 125 mg every 12 hours for 2 days. After extubation oral prednisone was begun (1 mg/kg tapered to 0.1 mg/kg per day within 12 months with no attempts at complete withdrawal). The same protocol of prednisone dose tapering was employed in all patients. Azathioprine administration was initiated at a dosage of 2 mg/kg/d and adjusted to maintain the white blood cell count between 4000 and 6000/mm3. Administration of oral cyclosporine (3 mg/kg) was begun only after hemodynamic stabilization and normalization of renal function. Doses were adjusted to achieve blood levels of 300 ng/dL during the first 12 months, as measured by a whole blood radioimmunoassay. After 12 months, the cyclosporine level was maintained between 150 and 200 ␮g/dL.

Rejection Diagnosis and Treatment Rejection was assessed by routine endomyocardial biopsy: weekly for the first 2 months, then every 2 weeks during the third month. Further endomyocardial biopsies were performed as dictated by the patient’s clinical condition. The International Society of Heart and Lung Transplantation (ISHLT) grading system was used at histology examination.12 Rejection episodes of grade 3A or greater were treated with 1000 mg/d methylprednisolone sodium succinate intravenously for 3 consecutive days. Steroid resistant rejections (need for more than two “pulses” of steroid therapy) were treated by switching from cyclosporine to tacrolimus (FK506) and/or by a 9-day course of OKT3 (5 mg/d).

Infection Prophylaxis The study population received prophylactic amoxicillin plus clavulanic acid (2.2 g preoperatively, then every 8 hours) for the first 48 hours. Fungal infection prophylaxis included oral administration of nystatin and mouthwashes with amphotericin B suspension. Antiviral prophylaxis used 400-mg acyclovir administration every 12 hours for 2 months; hyperimmunglobulins were not used in any patient.

Surveillance for Infection Patients were screened for bacterial infections through routine bacterial cultures from blood, urine, and tracheobronchial secretions when the body temperature exceeded 38°C. Pretransplant assessment of viral infection in both the recipient and the donor was based on serology (IgG and IgM) for cytomegalovirus (CMV), herpes simplex, varicella zoster, and Epstein-Barr virus. Posttransplant surveillance of CMV infection was performed by monitoring blood early antigen (pp-65) at the time of each visit during the first 3 months, and then monthly up to the sixth month. When the results were positive (ⱖ10 cells/2 ⫻ 105 polymorphonuclear leukocytes [PMN]), preemptive therapy was delivered with intravenous ganciclovir (5 mg/kg twice daily, with dosage adjustment according to renal function) for 15 days, followed by oral ganciclovir for 1 month.

Surveillance of Graft Atherosclerosis The protocol for graft atherosclerosis surveillance included coronary angiography at 1, 3, and 5 years after transplantation. Further angiograms were performed as dictated by the patient’s clinical conditions and/or echocardiographic findings.

RABBIT-ANTITHYMOCYTE GLOBULIN INDUCTION THERAPIES Table 1. Comparison Between the Two Groups as to Recipient Characteristics

Age Weight Male sex Diagnosis Idiopathic Ischemic Other UNOS status 1 PRA % PVR CMV⫹

Group A

Group B

P

38.9 ⫾ 14.6 68.3 ⫾ 10 12 (60%)

42.5 ⫾ 13.5 73.3 ⫾ 11.6 17 (85%)

.423 .153 .08

10 (50%) 4 (20%) 6 (30%) 7 (35%) 2% 2.8 ⫾ 1.4 16 (80%)

10 (50%) 6 (30%) 4 (20%) 3 (15%) 4% 3.0 ⫾ 1.8 14 (70%)

.352 .137 .56 .78 .38

PRA % ⫽ mean preoperative rate of panel reactive antibodies and pulmonary vascular resistances; PVR ⫽ pulmonary vascular resistences (in WU).

Data Collection Clinical and laboratory data were prospectively entered into a computerized database. Preoperative data including etiology, age, weight, and United Network of Organ Sharing (UNOS) status were collected for each patient. Age, total ischemic time, and level of inotropic support at graft harvesting were entered for each donor. In particular, high inotropic support was defined as dobutamine or dopamine ⬎10 ␮g/kg/min and/or infusion of norepinephrine regardless of dosage. The data set included the number of rejection episodes (ISHLT severity ⱖ 1B) in the first 6 months after transplantation, the time between transplantation and the first rejection episode, as well as the occurrence of steroid-resistant rejections, of infection episodes, of CMV disease (or reactivation), of graft atherosclerosis, of malignancies, and of deaths. The appearance of major or minor side effects caused by induction antibodies as well as the need for withdrawal due to anaphylaxis or leukopenia or thrombocytopenia were also recorded.

Study Endpoints and Statistical Analysis The primary efficacy assessment included comparisons between the two groups of patients with regard to early posttransplant (6 months) incidence of acute rejection episodes (grade ⱖ 1B), bouts of steroid-resistant rejection, and time to first rejection. Other endpoints were survival, graft atherosclerosis, infections, and malignancies. Data were expressed as mean values and standard deviations. Categorical variables were compared by Fischer exact test or Mann-Whitney U test when appropriate; for continuous variables a two-tailed Student t test or Wilcoxon rank-sum test. Table 2. Comparison Between the Two Groups as to Donor Characteristics

Age Cause of death Trauma Vascular Other High dosage of IS D/R size mismatch Ischemia time CMV D⫹/R⫺

Group A

Group B

P

31.2 ⫾ 10.9

33.5 ⫾ 10.6

.504

10 (50%) 8 (40%) 2 (10%) 5 (25%) 3 (15%) 175.6 ⫾ 38.1 2 (10%)

.353

11 (55%) 6 (30%) 3 (15%) 8 (40%) 1 (5%) 167.4 ⫾ 54 1 (5%)

D/R ⫽ donor/recipient; IS ⫽ inotropic support.

633 Table 3. Comparison Between the Two Groups as to Maintenance Immunosuppression (See Text, Methods Section, for Description of Criteria Employed in Therapy Adjustment) Group A (mean ⫾ SD)

CYS blood concentration 1 week 174.8 ⫾ 86.2 1 month 320.8 ⫾ 103.0 2 months 320.2 ⫾ 184.6 3 months 275.0 ⫾ 105.5 6 months 239.0 ⫾ 111.6 12 months 301.4 ⫾ 108.6 24 months 233.4 ⫾ 82.4 36 months 176.6 ⫾ 95.7 WBC count 1 month 5700.0 ⫾ 1332.7 2 months 6189.5 ⫾ 989.9 3 months 5636.8 ⫾ 902.7 6 months 4911.5 ⫾ 1013.7 12 months 3956.3 ⫾ 953.7 24 months 4021.5 ⫾ 631.3 36 months 5846.3 ⫾ 1081.7

Group B (mean ⫾ SD)

P

145.5 ⫾ 43.9 305.74 ⫾ 156.5 312.7 ⫾ 95.9 291.2 ⫾ 105.6 217.7 ⫾ 82.9 272.8 ⫾ 51.7 193.0 ⫾ 49.6 168.8 ⫾ 102.3

.195 .727 .876 .640 .509 .306 .076 .652

5494 ⫾ 400.9 6657 ⫾ 256.7 6191.0 ⫾ 1330.5 5086.3 ⫾ 411.3 4398.9 ⫾ 359.4 4455.2 ⫾ 702.9 5336.6 ⫾ 846.3

.828 .752 .427 .151 .423 .428 .542

CYS ⫽ cyclosporine; WBC ⫽ white blood count.

One-way ANOVA for repeated measurements was performed to analyze blood levels and mean cyclosporine dosages. Analyses on survival and freedom from events times were performed with the Kaplan-Meier method. Differences in actuarial data were analyzed by log-rank tests. The level of statistical significance was established at 95% (P ⬍ .05). The analysis used a SPSS 10.1 statistical program.

RESULTS

The results presented in this paper have been obtained at a mean follow-up of 32.8 ⫾ 8.9 months (range 5.1 to 45.8 months). The length of the follow-up did not differ significantly between the two study groups (33.3 ⫾ 9.1 in group A, 32.4 ⫾ 8.9 in group B, P ⫽ .75). All patients had been followed to this time. Demographics

Tables 1 and 2 report donor and recipient characteristics in both treatment groups, respectively. The recipients proved to show similar age, weight, sex, pretransplant cardiac diagnosis, UNOS status, preoperative rate of panel reactive antibodies, and pulmonary vascular resistances in both groups. No statistical difference was observed with regard to donor age, cause of death, percentage of high inotropic support at harvesting (as defined above), donor-recipient body surface area matching, and total postretrieval cold ischemia time. Survival

.25 .302 .582 .50

The overall actuarial survival rate at 1 and 3 years was 95% with no difference between the two groups (P ⫽ .98): one patient belonging to group A died at 5.15 months after transplantation due to multiple-organ failure following a pulmonary infection due to Nocardia and Aspergillus fu-

634

DE SANTO, DELLA CORTE, ROMANO ET AL

Fig 1. Kaplan-Meier actuarial freedom from rejection ⬎1B in patients treated with thymoglobulin (group A) and ATG-Fresenius (group B).

migatus. One group B patient died at 5.64 months after a cerebrovascular accident. Rejection

Table 3 shows no significant differences in the maintenance immunosuppressive regimen at several fixed times (up to 36 months posttransplantation). Acute rejection grade 1B or higher was observed at biopsy of five patients in group A and four in group B (P ⫽ .50). The number of early (within 6 months) rejection of grade higher than 1B was three in each group (P ⫽ .67). The actuarial rate of freedom from a rejection episode is shown in Fig 1 (P ⫽ .68). The mean time to first cardiac rejection was 2.22 ⫾ 1.5 months in the thymoglobulin group and 0.55 ⫾ 0.4 months in the ATG group (P ⫽ .13). The number of acute rejection episodes requiring one or more courses of steroid pulse therapy (grade 3A) was two in group A and two in group B (P ⫽ .69). One patient in group A developed steroid-resistant rejection, undergoing rescue treatment with OKT3. Infections

Infections represented the most frequent posttransplant complications in our series, namely an overall incidence of

25%. With regard to bacterial and fungal infections, six episodes occurred in four patients in group A and three in three group B patients. No significant differences were observed between the two study groups in terms of actuarial freedom from bacterial or fungal infection rates (P ⫽ .29). One patient developed Staphylococcal mediastinitis, while six patients experienced low respiratory tract infections, namely, Streptococcus pneumoniae in one, S aureus in one, Legionella pneumophila in two, and Nocardia asteroides in two. Two of the five patients who developed bacterial pneumonia subsequently developed fungal pneumonia (both belonged to group A): the first, a fatal Aspergillus pneumonia following Nocardia infection; the second, Candida pneumonia 6 months after an initial Legionella pneumonia, the former cured by Amphotericin B treatment. Among viral infections, CMV reactivation was observed in 13 patients belonging to group A (65%) and six in group B (30%; P ⫽ .028). The entire study population showed three CMV mismatches: one in group A and two in group B (P ⫽ .50). Signs and symptoms of CMV disease (fever, leukopenia, pneumonia) occurred only in group A (four patients; 20%; P ⫽ .05). No significant difference was observed in terms of incidence of CMV disease between high- (R⫺/ D⫹) and low-risk patients (33% vs 8.1%; P ⫽ .28).

RABBIT-ANTITHYMOCYTE GLOBULIN INDUCTION THERAPIES

Malignancies and Graft Atherosclerosis

No cases of malignancies or lymphoproliferative diseases were observed throughout the study period. Due to the short follow-up of 3 years after transplantation, no difference was detected in the incidence of graft atherosclerosis of any degree: two of nine patients in group A, two of seven patients in group B (P ⫽ .61). Adverse Reactions to Induction Therapy

Major adverse reactions, such as leukopenia or thrombocytopenia, requiring withdrawal of the induction therapy were observed in one patient in group A and one in group B. Minor adverse effects developed in two patients in group A (fever with rigors in one, headache and cutaneous rash in another) and one in group B (fever). In all three cases the reaction was self-limiting; none was withdrawn from therapy. DISCUSSION

During the last decade many studies have been sought to compare antibody preparations commercially available for posttransplant induction therapy. In particular, most studies compared the results obtained with anti-CD3 murine monoclonal antibodies (Orthoclone, OKT3) with horse or rabbit polyclonal reagents.13–16 OKT3 proved to be a more aggressive therapy, resulting in higher rates of lymphoproliferative disorders,15 of adverse reactions, and of viral infections.16 Recently, Bourdage et al17 compared the in vitro properties of different types of antithymocyte immunoglobulin. They demonstrated that antithymocyte immunoglobulins obtained from the same animal species can have different immunosuppressive characteristics depending on the immunogen and the elicited types of antibodies. To our knowledge only three studies have compared thymoglobulin and ATG, the two principal available rabbit polyclonal antithymocyte antibodies.18 –20 The results of these studies were not comparable on meta-analysis. The main evidence emerging from the present prospective randomized study is that the two rabbit-antithymocyte globulin have different immunosuppressive effects when employed for induction therapy. Although the incidence of acute rejection episodes was not different between patients treated with thymoglobulin versus ATG, the incidence of early postoperative viral infections was significantly higher among the thymoglobulin group. The former finding is consistent with both the retrospective analysis of 49 patients performed by Krogsgaard and coworkers,18 and the prospective comparison by Leger and Pavie,19 in which, however, a surprisingly higher rate of rejections was observed than that reported in the literature. On the contrary, in a retrospective analysis of 484 patients Zuckermann et al20 claimed better prevention of rejection with the use of thymoglobulin, despite a fourfold greater daily dosage of ATG-fresenius. Indeed, due to the retrospective design and the length of the study period, the two groups belonged to different eras and the difference in rejection incidence

635

barely reached statistical significance when the analysis was performed between concurrent subgroups of patients. Moreover, the groups were not homogeneous with respect to risk factors (most importantly, recipient age was significantly lower among the ATG group). Bourdage and Hamlin17 have shown that ATG-fresenius shows less powerful blocking of CD4 in vitro compared with other antithymocyte preparations, including thymoglobulin. Nevertheless, in our clinical experience using the same daily dosage, thymoglobulin (administered during the first 5 postoperative days) and ATG-fresenius (continued until the postoperative day 7) showed equivalent efficacy to prevent acute rejection. Our study population was homogeneous in terms of major risk factors for mortality, acute rejection, and other morbidities; the maintenance immunosuppressive regimen was similar as well. Greater knowledge of the effects of rabbit antithymocyte globulins on humoral immunity and on regulation networks will be necessary to accurately interprete the results. The importance of differences in the schemes of administration (eg, different dosages and duration of therapy) must be further investigated as well. Interestingly, Mu ¨ller21 observed a significantly decreased number of B cells in renal transplant recipients receiving thymoglobulin compared to ATG-fresenius. In contrast other authors10 have suggested a possibility of early acute humoral rejection after induction therapy with thymoglobulin; however, the reagent was administered at 2.5 mg/kg for the first postoperative day, followed by 1.5 mg/kg/d for the next 4 days. A major criticism for induction therapies is the increased incidence of early postoperative opportunistic infections, in particular CMV disease. In the above cited work by Krogsgaard and colleagues,18 thymoglobulin caused a higher incidence of CMV reactivation; however, the validity of the conclusion was limited by inclusion in the control group of patients who received ATG-fresenius, ATGAM or no induction therapy. On the contrary, Leger and Pavie19 reported a higher rate of infections among ATG-Fresenius–treated patients. In the study by Zuckermann et al, viral infections as well as CMV reactivations, occurred more often in the thymoglobulin group, but there was no difference in the rate of appearance of CMV disease in CMV negative recipients (high risk) probably due to the prophylactic use of anti-CMV hyperimmunoglobulin.20,22 In our study there was no difference between the two groups with regard to bacterial or fungal infections; the overall incidence of infective complications was similar to that reported in most large series. A significantly higher incidence of CMV reactivations was recorded in patients treated with thymoglobulin; furthermore, all cases of primary CMV infection were observed in the thymoglobulin group. Again the reported stronger suppression of CD4 by thymoglobulin17 may explain its marked tendency to favor CMV reactivation, which requires the action of effectormemory CD4(⫹) T cells23,24: the development of CMV infections has already been found to be associated with significant reduction of CD4(⫹) T-cells in renal transplant recipients.25

636

As to graft atherosclerosis, the substrate of chronic rejection, we observed both treatment groups to show comparable incidences of vasculopathy upon angiography: the overall rate was consistent with the results of the largest series.26,27 It has been shown that up to 50% of heart transplant recipient have some degree of graft atherosclerosis within 3 years after the operation.28 CMV infections29 and multiple early acute rejection episodes30 have been proposed to be predisposing factors for this complication. Therefore the benefits and risks of an induction antibody preparation may not only affect early outcomes, but also influence long-term morbidity and cardiac-related mortality. Longer follow-up (⬎5 years) is necessary to detect possible differences between the study groups in terms of chronic rejection. As to the supposed role of polyclonal antibodies in the increased risk of malignancies or lymphoproliferative diseases, no cases of malignancies were observed at our follow-up of 32.8 ⫾ 8.9 months. Zuckermann et al20 retrospectively observed an earlier incidence of malignancies among patients treated with thymoglobulin which were the most recent group in that study compared with ATG, despite the latter group having higher induction therapy dosages, similar malignancy rates, and longer follow-up. Therefore, a real concern about the use of thymoglobulin may be an even more increased incidence of malignancies in the long-term follow-up. In conclusion, the present prospective randomized study demonstrated that although thymoglobulin and ATG-Fresenius at the same dosages have shown equivalent efficacy in rejection prevention, they have distinct immunological properties and are therefore associated with different rates of CMV reactivations/infections. In particular, in our series thymoglobulin resulted in a significantly higher risk of CMV reactivation. The effects on late survival and long-term freedom from events needs to be further assessed in a larger series and with a longer follow-up time. Limitations of the Study

The main limitation in our study is the relatively low number of enrolled patients, which could have negatively affected the power of the study results, namely the failure to statistically show the observed tendency toward an earlier occurrence of acute rejection episodes among patients treated with ATG than those who received thymoglobulin. However, the entire study population was treated during a concentrated time period, thus achieving a uniformity of methods between the two groups. Indeed, series encompassing different eras may be biased by advances in diagnostic, prophylactic and therapeutic techniques. This study is to our knowledge the only prospective randomized comparison between the effects of thymoglobulin and ATGfresenius. REFERENCES 1. Hosenpud JD, Bennet LE, Keck BM: The Registry of the International Society for Heart and Lung Transplantation: seventeenth official report—2000. J Heart Lung Transplant 19:909, 2000

DE SANTO, DELLA CORTE, ROMANO ET AL 2. Joun R, Rajasinghe HA, Chen JM, et al: Long-term outcomes after cardiac transplantation: an experience based on different eras of immunosuppressive therapy. Ann Thorac Surg 72:440, 2001 3. Spratt P, Esmore D, Baron D, et al: Effects of low-dose cyclosporin A on toxicity and rejection in cardiac transplantation. Transplant Proc 19:2847, 1987 4. Carrier M, Jenicek M, Pelletier LC: Value of monoclonal antibody OKT3 in solid organ transplantation: a meta-analysis. Transplant Proc 24:2586, 1992 5. Carrier M, White M, Perrault LP, et al: A 10-year experience with intravenous thymoglobuline in induction of immunosuppression following heart transplantation. J Heart Lung Transplant 18:1218, 1999 6. Bonnefoy-Berard N, Revillard JP: Mechanisms of immunosuppression induced by antithymocyte globulins and OKT3. J Heart Lung Transplant 15:435, 1996 7. Genestier L, Fournel S, Flacher M, et al: Induction of Fas(Apo-1, CD95)-mediated apoptosis of activated lymphocytes by policlonal antithymocyte globulins. Blood 91:2360, 1998 8. Beaufigeau M, Dumesnil D, Carrier M, et al: Seven-year experience with rabbit antithymocyte globulin after cardiac transplantation at the Montreal Heart Institute. Transplant Proc 29:10S, 1997 9. Lavee J, Bar-Zohar D, Har-Zahav Y, et al: Immunosuppression induction with rabbit antithymocyte globulin in heart transplantation patients: 6-year experience at the Sheba Medical Center. Transplant Proc 32:737, 2000 10. Chien NC, Lin FL, Chou NK, et al: Rabbit antithymocyte globulin induction immunosuppression in heart transplantation. Transplant Proc 32:2380, 2000 11. Lower RR, Shumway NE: Studies on the orthotopic homotransplantations of the canine heart. Surg Forum 11:18, 1960 12. Billingham ME, Cary NRB, Hammond ME, et al: A working formulation for the standardization of nomenclature in the diagnosis of heart and lung rejection: heart rejection study group. J Heart Transplant 9:587, 1990 13. Kormos RL, Herlan DB, Armitage JM, et al: Monoclonal versus polyclonal antibody therapy for prophylaxis against rejection after heart transplantation. J Heart Transplant 9:1, 1990 14. Renlund DG, O’Connell JB, Gilbert EM, et al: A prospective comparison of murine monoclonal CD-3 (OKT3) antibodybased and equine antithymocyte globulin-based rejection prophylaxis in cardiac transplantation. Decreased rejection and less corticosteroid use with OKT3. Transplantation 47:599, 1989 15. Swinnen LJ, Costanzo-Nordin MR, Fisher SG, et al: Increased incidence of lymphoproliferative disorders after immunosuppression with the monoclonal antibody OKT3 in cardiac-transplant recipients. N Engl J Med 323:1723, 1990 16. Mcdonalnd PS, Mundy J, Keogh AM, et al: A prospective randomised study of prophylactic OKT3 versus equine antithymocyte globulin after heart transplantation. Increased morbidity with OKT3. Transplantation 55:110, 1993 17. Bourdage JS, Hamlin DM: Comparative polyclonal antithymocyte globulin and antilymphocyte/antilymphoblast globulin anti-CD antigen analysis by flow cytometry. Transplantation 59:1194, 1995 18. Krogsgaard K, Boesgaard S, Aldershvile J, et al: Cytomegalovirus infection rate among heart transplant patients in relation to anti-thymocyte immunoglobulin induction therapy. Scand J Infect Dis 26:239, 1994 19. Leger PH, Pavie A: Comparison de deux globulines antithymocytaires, Fresenius et Merieux, en tranplantation cardiaque. In Cabrol C, Gandjbakhch I, Pavie A (eds): Les Journees Hospital de la Pitie. Paris: 1994. 1995, p 103 20. Zuckermann AO, Grimm M, Czerny M, et al: Improved long-term results with thymoglobuline induction therapy after cardiac transplantation; a comparison of two different rabbitantithymocyte globulines. Transplantation 69:1890, 2000

RABBIT-ANTITHYMOCYTE GLOBULIN INDUCTION THERAPIES 21. Mu ¨ller TF: Long-term T cell dynamics following the use of polyclonal and monoclonal antibodies. Graft 21:15, 1999 22. Balk AH, Weimar W, Rothbarth PH, et al: Passive immunization against cytomegalovirus in allograft recipients. The Rotterdam heart transplant program experience. Infection 21:195, 1993 23. Gamadia LE, Remmerswaal EB, Weel JF, et al. Primary immune responses to human cytomegalovirus: a critical role for IFN-gamma-producing CD4⫹ T cells in protection against CMVdisease. Blood 101:2686, 2003 24. Sester M, Sester U, Gartner BC, et al: Dominance of virus-specific CD8 T cells in human primary cytomegalovirus infection. J Am Soc Nephrol 13:2577, 2002 25. Essa S, Pacsa AS, Raghupathy R, et al: CD4(⫹) T cell levels are decreased during active CMV infection in kidney transplant recipients. FEMS Immunol Med Microbiol 34:17, 2002 26. John R, Rajasinghe H, Chen JM, et al: Impact of current management practices on early and late death in more than 500

637 consecutive cardiac transplant recipients. Ann Surg 232:302, 2000 27. McGiffin DC, Kirklin JK, Naftel DC, et al: Competing outcomes after heart transplantation: a comparison of eras and outcomes. J Heart Lung Transplant 16:190, 1997 28. Gao SZ, Schroeder JS, Aldermann EL, et al: Prevalence of accelerated coronary artery disease in heart transplant survivors: comparison of cyclosporine and azathioprine regimens. Circulation 80:S100, 1989 29. Koskinen PK, Nieminen MS, Krogerus LA, et al: Cytomegalovirus infection accelerates cardiac allograft vasculopathy: correlation between angiographic and endomyocardial biopsy findings in heart transplant recipients. Transplant Int 6:341, 1993 30. Zerbe T, Uretsky B, Kormos R, et al: Graft atherosclerosis: effects of cellular rejection and human lymphocyte antigen. J Heart Lung Transplant 11:S104, 1992