A RANDOMIZED ACTIVE-CONTROLLED TRIAL OF MYCOPHENOLATE MOFETIL IN HEART TRANSPLANT RECIPIENTS1 : Transplantation

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Clinical Transplantation

A RANDOMIZED ACTIVE-CONTROLLED TRIAL OF MYCOPHENOLATE MOFETIL IN HEART TRANSPLANT RECIPIENTS1

Kobashigawa, Jon2,3; Miller, Leslie; Renlund, Dale; Mentzer, Robert; Alderman, Edwin; Bourge, Robert; Costanzo, Maria; Eisen, Howard; Dureau, Georges; Ratkovec, Ranae; Hummel, Manfred; Ipe, David; Johnson, Jay; Keogh, Anne; Mamelok, Richard; Mancini, Donna; Smart, Frank; Valantine, Hannah The Mycophenolate Mofetil Investigators

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Abstract

*Abbreviations: ATG, antithymocyte globulin; ICUS, intracoronary ultrasound; ISHLT, International Society for Heart and Lung Transplantation; MMF, mycophenolate mofetil; OKT3, murine monoclonal anti-CD3 antibody.

Heart transplantation is an established treatment modality for selected patients with end-stage heart disease. World wide, more than 40,000 patients have undergone heart transplantation, and approximately 3,000 new patients receive human heart allografts each year (1). Ideally, pharmacological immunosuppression after heart transplantation would prevent the morbidity and mortality associated with allograft rejection without immunosuppressive side effects or drug toxicities. When used alone, however, available immunosuppressive agents are generally incapable of preventing cardiac allograft rejection without unacceptable toxicity. Consequently, multiple drugs are used to minimize the toxicity of individual agents(2). Current practice utilizes three immunosuppressive drugs: cyclosporine (an inhibitor of calcineurin and subsequent interleukin-2 production), azathioprine (a prodrug of 6-mercaptopurine that inhibits both de novo and salvage pathways for purine biosynthesis), and corticosteroids(inhibitors of cytokine gene transcription) (3), but this regimen is associated with 1- and 5-year survival rates of only 79% and 63%, respectively (1), and no appreciable change in outcome in the past decade. After transplantation, most patients experience at least one episode of cardiac allograft rejection, many patients develop an infection requiring intravenous antibiotics (4-8), and coronary artery disease develops in the majority of cardiac allografts within 5 years (9,10). Thus, more effective and safer immunosuppressive drugs are needed to promote the long-term survival of cardiac allograft recipients.

Mycophenolate mofetil (MMF*), which is rapidly hydrolyzed after ingestion to mycophenolic acid, is a selective, noncompetitive, reversible inhibitor of inosine monophosphate dehydrogenase, a key enzyme in the de novo synthesis of guanine nucleotides (11). Unlike other marrow-derived cells and parenchymal cells that use the hypoxanthine-guanine phosphoribosyl transferase (salvage) pathway (12), activated lymphocytes rely predominantly on the de novo pathway for purine biosynthesis. This functional selectivity allows lymphocyte proliferation to be specifically targeted with less anticipated effect on erythropoiesis and neutrophil production than is seen with azathioprine(13).

MMF has been shown to be effective in inhibiting transplant rejection and in prolonging allograft survival in experimental animals(14). In human cadaveric renal transplantation, MMF decreased rejection by 50% at 1 year and decreased the use of antilymphocyte antibodies for the treatment of severe corticosteroid-resistant rejection(15). Dose ranging and refractory rejection trials in human heart transplant recipients suggest that MMF, when substituted for azathioprine in standard triple-drug therapy regimens, is well tolerated and might be more efficacious than azathioprine (13,14,16).

Given currently available in vitro, animal, and human experience(13,15) with MMF, a prospective comparison of MMF and azathioprine was undertaken in patients additionally receiving cyclosporine and corticosteroids after cardiac transplantation. First-year results, including 6-month allograft rejection and 1-year survival data, are reported.

METHODS

Six hundred and fifty patients, undergoing their first cardiac transplant at 28 heart transplant centers in Australia, Europe, and North America were enrolled in this 3-year, double-blind, active-controlled trial. All met standard acceptance criteria (17), were 18 years of age or older, and were transplanted between February 1994 and July 1995. The trial was approved by the Institutional Review Board of each participating center, and every patient gave written, informed consent. All patients were enrolled and randomized in the study before transplantation, but study drug was not initiated until the patient was able to take oral medications. Patients unable to take medications orally more than 5 days after surgery were to be withdrawn from the study.

Drug therapy. Each center determined whether early rejection prophylaxis with antithymocyte globulin (ATG) or the murine monoclonal anti-CD3 antibody (OKT3) was used postoperatively in that center's patients according to standard practice at the institution. If antilymphocyte therapy was used after transplantation, ATG (10-20 mg/kg/day) or OKT3 (1-5 mg/day) was given for 5-14 days beginning on the first postoperative day. Cyclosporine was begun 2-4 days postoperatively at a dose of 2-8 mg/kg/day orally. If antilymphocyte therapy was not used after transplantation, cyclosporine was begun preoperatively at a dose of 1-4 mg/kg intravenously or 3-8 mg/kg orally.

In all patients, cyclosporine was titrated to maintain a trough level reflecting the standard target assay range at each center. Methylprednisolone(500-1000 mg) was administered intravenously pre- or intraoperatively. After surgery, methylprednisolone in a dose up to 500 mg was given within 12 hr. Oral prednisone (or an intravenous equivalent) was thereafter begun at a dose of 1 mg/kg/day and tapered to 0.3 mg/kg/day by 30 days after transplant, 0.15 mg/kg/day by 90 days after transplant, and 0.1 mg/kg/day by 180 days after transplant. Azathioprine at 4 mg/kg was given preoperatively to all patients. The use of concomitant medication for cytomegalovirus, Pneumocystis carinii, herpes simplex, peptic ulcer disease, and osteoporosis prophylaxis was according to standard institutional practice and was not controlled for in this study.

Once able to take medications orally, patients received, in addition to cyclosporine and prednisone, one active drug and one placebo drug (either MMF at 1500 mg twice daily and azathioprine placebo once daily or azathioprine 1.5-3 mg/kg/day in 50-mg capsules once daily and MMF placebo twice daily). Investigators were allowed to decrease the study medicines in the case of an adverse event. This was accomplished by decreasing the dose of both study drugs, the MMF/placebo dose in 1000 mg/day increments and the azathioprine/placebo in 50 mg/day increments simultaneously. Study drug could be increased in similar increments up to 4000 mg/day MMF/placebo and 50 mg/day azathioprine/placebo more than the initial dose for allograft rejection failing to resolve with treatment.

Follow-up of patients. Baseline assessments were completed at the time of transplantation. Information collected included demographic data, cytomegalovirus serologic status of recipient and donor, results of panel-reactive antibody test, B-cell and T-cell crossmatch, donor age, ischemic time, and a medication history. During the first year after transplant, all patients (including those who terminated early from the study) were observed for the occurrence of adverse events, laboratory abnormalities, cardiac allograft function, rejection episodes (during the first 6 months after transplant), allograft loss, infections, neoplastic diseases, and allograft coronary artery disease. The occurrence of adverse events, laboratory abnormalities, and infections were reported while patients were on study medications. The blind for patients was not broken when patients were terminated from the trial. The study was planned as a 3-year study and is still ongoing, although primary end points were assessed at 6 months for rejection and 1 year for graft loss.

The total daily doses of cyclosporine, corticosteroids, and other immunosuppressive drugs were recorded, and a study drug pill count was performed to assure compliance. Cardiac allograft ventricular function was assessed by either fractional shortening or ejection fraction at 6 and 12 months by echocardiogram, radionuclide, or contrast angiography.

Endomyocardial biopsies/rejection treatment. Endomyocardial biopsies were performed weekly for 4 weeks, every other week for 2 months, monthly for 3 months, and every other month until the anniversary of the transplant was reached. Biopsies were also performed if clinically indicated. Endomyocardial biopsies were graded by local pathologists according to International Society for Heart and Lung Transplantation (ISHLT) standardized criteria (18). Cardiac allograft rejection treatment was regimented for the first 6 months. In the absence of allograft dysfunction, ISHLT grades 1A and 1B were not treated. Grades 2, 3A, 3B, and 4 were treated with at least 3 days of oral or intravenous corticosteroids with a cumulative dose of more than 300 mg. Rejection, whether biopsy proven or presumed, was treated regardless of grade in the presence of significant allograft dysfunction. Hemodynamic compromise was defined as a pulmonary capillary wedge pressure ≥20 mmHg or 25% increase, a cardiac index ≤2.0 L/min/m2 or 25% decrease from baseline, an ejection fraction≤30%, a pulmonary artery oxygen saturation ≤60%, the presence of a new S3 gallop, or a fractional shortening ≤20% or 25% decrease from baseline. Resolution of rejection was defined as one subsequent biopsy that was grade 0 or two successive biopsies that were no greater than 1B. Rejection episodes failing to respond to initial corticosteroid treatment or accompanied by hemodynamic compromise were treated with further corticosteroids and OKT3.

Allograft coronary artery disease: assessment and diagnosis. Quantitative angiography and intracoronary ultrasound (ICUS) were scheduled at 1-8 weeks after transplant (baseline) and at 12 months. The angiography and ICUS images were evaluated and measured by a separate core angiography laboratory (Stanford University) and a core ICUS laboratory (University of California, Los Angeles, CA), whose members were blinded to the treatment group.

Coronary angiography was performed before ICUS examination using a minimum of four projections of the left coronary system and two projections of the right coronary artery. Nitroglycerin administration was generally sublingual or intracoronary, before coronary angiography. Incremental nitroglycerin administration was intracoronary before ICUS imaging. The nitroglycerin protocol used at baseline assessment was reproduced at the 12-month angiographic and ICUS follow-up study. Cine film recording used a 6- to 8-inch image intensifier mode. The recordings of 7- or 8-French contrast-filled catheters provided scaling factors for measuring luminal diameters via computerized vessel edge detection software. Each clinical site laboratory was required to image a calibration grid in the procedure rooms planned for these studies, to assess pin cushion distortion. All films were then transferred to the angiographic core laboratory.

ICUS imaging began immediately upon accessing a selected coronary artery with 30-MHz probes (4.3 French, CVIS, Sunnyvale, CA; 3.5 French, Hewlett-Packard, Palo Alto, CA). ICUS imaging of the most distal position was documented with cineangiography and contrast injection, and a continuous 30-second slow pullback was performed. Recorded videotape images were analyzed at the core imaging laboratory by morphometric analysis(19), using 10 evenly spaced positions from the ICUS pullback. All measurements were recorded during diastole on Super-VHS video and analyzed by computerized planimetry. The following measurements (mean of the 10 positions) were obtained: (1) maximal intimal thickness; (2) intimal area; (3) intimal index=intimal area ÷ (lumen area + intimal area); (4) maximum/minimum diameters of lumen; (5) lumen area; and (6) degree of vessel wall involvement. Two blinded observers performed the measurements from selected frames at baseline and 1 year. Changes in intimal thickness, indices, and lumen dimensions were assessed, with each patient serving as his/her own control.

Statistical analysis. Analysis of efficacy was based on two populations: (1) all enrolled patients and (2) the subset of patients receiving at least a single dose of study medication (treated population). Both analyses were prespecified in the study protocol. The treated population was analyzed due to the fact that 72 enrolled patients (11%) were withdrawn from the study in the perioperative period and did not receive study medication largely due to a transient inability to take or absorb oral study medication. Unlike the circumstance for azathioprine, an intravenous form of MMF was not available when the present study commenced. In addition, the different color of MMF if given via a nasogastric tube would have led to inadvertent unblinding. Analyses in both populations included both on-study and posttermination information.

The primary end points were: (1) proportion of patients who died or who were retransplanted and (2) proportion of patients with first biopsy-proven rejection with hemodynamic compromise or retransplantation or death. The study was designed with adequate power to demonstrate statistical equivalence for the graft loss (death/retransplantation) end point and statistical superiority for MMF for the primary rejection end point. Secondary end points included: (3) proportion of patients with first treated biopsy-proven rejection or presumptive rejection (i.e., treated rejection in the absence of a positive biopsy); (4) proportion of patients with first biopsy-proven rejection or presumptive rejection treated with OKT3 or ATG; (5) proportion of patients with new development or progression of coronary artery disease as assessed by qualitative angiography; (6) average change in luminal diameter from baseline measured by quantitative angiography; (7) average change in the mean coronary artery maximal intimal thickness, intimal area, and intimal index from baseline measured by ICUS; and (8) maintenance dose of corticosteroids and cyclosporine at 6 and 12 months after transplant. Supplemental posthoc end points proposed by the Steering Committee included:(9) proportion of patients with first biopsy-proven rejection of moderate grade (grade 3A or greater); (10) proportion of patients with first biopsy-proven rejection with redefined hemodynamic compromise criteria; and(11) average change in coronary artery lumen area from baseline measured by ICUS. The above end points were all analyzed for 6 months after transplant except for end points 1, 5, 6, 7, and 11, which were analyzed during the 12 months after transplant.

Statistical analysis for patient death or retransplantation at 1 year was accomplished using the one-sided 97.5% confidence interval and a Mantel-Haenszel-type statistic adjusted by the investigator and weighted proportional to the sample size (20). The Cochran-Mantel-Haenszel chi-square test, stratified by investigator(21), was performed for end points with categorical data. For continuous data, analysis of variance or covariance with treatment, investigator, and treatment by investigator factors was used. Baseline measurements were considered as covariates in analysis of covariance. Time-to-event analyses were performed using log-rank statistics, and the Cox proportional hazard regression methodology was used to account for treatment effects and other clinically relevant risk factors(22). The Kaplan-Meier method was used to plot time-to-event data. Comparability of treatment groups at baseline was assessed using a two-factor analysis of variance for continuous variables and the Cochran-Mantel-Haenszel chi-square test, stratified by investigator for categorical variables. Adverse events and opportunistic infections were classified using a standard thesaurus of preferred terms and were summarized descriptively. A posthoc subset of selected adverse events were analyzed using the Fisher exact test.

All tests of hypothesis, other than for graft loss, were two-sided with the standard null hypothesis of no difference between treatments versus the two-sided alternative. The significance level was defined asP<0.05 and marginal significance was defined asP<0.10.

RESULTS

There were 650 patients (327 MMF and 323 azathioprine patients) who were enrolled and randomized in the study. Data analyses were performed separately on the 650 enrolled patients and on those 578 treated patients (289 in both the MMF and azathioprine groups) who received at least one dose of study medication. Baseline demographics between the MMF and azathioprine groups were similar in both the enrolled-patient and treated-patient populations(Table 1).

T1-16
Table 1:
Patient Demographics in Enrolled, Treated, and Nontreated Patientsa

Baseline demographics were also similar among the 72 patients (38 MMF and 34 azathioprine patients) who were withdrawn before receiving study medications (Table 1). During the 12 months after transplant, 40 of these patients (56%) died or received a retransplant. There was some imbalance observed in these deaths because 24 (63%) had been randomized previously to MMF, and 16 patients (47%) had been assigned to azathioprine (P=0.163). There were no major differences in the cause of death between the MMF and azathioprine groups except for early posttransplant organ failures. Ten patients died secondary to graft failure or multiple organ failure that occurred within 10 days of transplant, of which 8 were in the MMF group and 2 were in the azathioprine group.

Survival. In the enrolled patients, there was no significant difference in mortality between the MMF group and the azathioprine group within the first 12 months after transplant. There were 42 deaths/retransplants in the MMF group (12.8%) and 49 deaths/retransplants in the azathioprine group (15.2%) (P=0.460). Only four patients (two in each group) underwent retransplantation during the first postoperative year.

In the treated patients, mortality was significantly lower in the MMF group compared with the azathioprine group at 12 months. There were 18 deaths in the MMF group (6.2%) compared with 33 deaths in the azathioprine group(11.4%), representing a 45% reduction in mortality (Fig. 1,P=0.031). The causes of death are presented in Table 2. Death due to rejection or infection/sepsis accounted for 9 MMF and 19 azathioprine deaths. There was one retransplant performed among the patients who received study drug; however, this patient died within 1 month after retransplant.

F1-16
Figure 1:
One-year survival of the MMF and azathioprine (Aza) groups in the treated-patient population. Patients receiving MMF had significantly greater survival.
T2-16
Table 2:
Causes of death in the treated patients

Rejection. In the enrolled patients, the numbers of patients with treated rejection (any ISHLT biopsy grade), biopsy-proven rejection ≥ grade 3A, any rejection treated with OKT3 or ATG, and biopsy-proven rejection with hemodynamic compromise or death/retransplant at 6 months after transplant were not statistically different between the MMF and azathioprine groups (see Table 3), but the proportion of patients was numerically lower in all categories in the MMF patients.

T3-16
Table 3:
Treated rejection in study patients during 6 months after transplanta

In the treated patients, the MMF group had significantly more patients who were rejection-free (biopsy proven or presumed) at 6 months compared with the azathioprine group (34.3% versus 26.3%, respectively;P=0.039) (Fig. 2). For specific treated rejection grades, there was a trend for the MMF group to have fewer patients with any rejection treated with OKT3 or ATG (P=0.061) and fewer patients with biopsy-proven rejection ≥ grade 3A (posthoc end point,P=0.055) (Table 3). Biopsy-proven rejection with hemodynamic compromise or death/retransplant at 6 months after transplant in the treated patients was similar in the MMF and azathioprine groups: 92 patients (32%) versus 100 patients (35%), respectively(P=0.339). However, the definition of hemodynamic compromise was broad, and the incidence was much higher than recently reported (5%) in a multicenter database (23), which used more restrictive criteria for hemodynamic compromise. The hemodynamic compromise criteria of pulmonary capillary wedge pressure, cardiac index, pulmonary artery saturation, and S3 gallop were deleted as these parameters are more likely to be influenced by primary changes in intravascular volume or state of peripheral vasoactivity. Therefore, hemodynamic compromise criteria included only an ejection fraction of ≤30%, a fractional shortening of ≤20% (or a 25% decrease from baseline), or the necessity for inotropic support. Using this more specific posthoc definition, there was significantly less biopsy-proven rejection with hemodynamic compromise or death/retransplant in the MMF group compared with the azathioprine group: 33 MMF patients (11.4%) versus 50 azathioprine patients (17.3%); P=0.045(Table 3). In this analysis, patients who died or were retransplanted before experiencing rejection with hemodynamic compromise were included as having met this end point. If such patients were excluded from this analysis, there would remain 19 MMF and 38 azathioprine patients with hemodynamically compromising rejection. In the follow-up of these patients during the 12 months after transplant, there were no deaths in the 19 MMF patients compared with 12 deaths in the 38 azathioprine patients (32%).

F2-16
Figure 2:
Freedom from rejection or allograft loss in heart transplant recipients in the MMF and azathioprine (Aza) groups of the treated-patient population. MMF was associated with a greater freedom from rejection and allograft loss (P value by log-rank statistic).

Allograft coronary artery disease. In the subset of enrolled patients who had both baseline and 12-month angiographic or ICUS studies, there were no significant differences between the MMF and the azathioprine groups in the angiographic or ICUS end points. The results of the treated patients are described below.

Coronary angiography: There were 193 MMF and 183 azathioprine patients with evaluable baseline and 12-month cineangiograms. There was no significant difference between the two groups in the development of new coronary artery disease or the progression of preexisting coronary artery disease: six MMF patients (3.1%) compared with nine azathioprine patients(4.9%); P=0.328. There was also no significant difference in the mean change in coronary artery diameter from baseline to 12 months after transplant between the two groups: vessel shrinkage of 0.11±0.02 mm in MMF patients compared with vessel shrinkage of 0.12±0.02 mm in azathioprine patients; P=0.701.

ICUS: There were 102 MMF and 94 azathioprine patients with evaluable baseline and 12-month ICUS studies. There was no difference in the change in ICUS measures of intimal thickness including maximal intimal thickness, intimal index, and intimal area from baseline to the 12-month study between the two groups (Table 4). The number of patients with a change in maximal intimal thickness >0.3 mm between the baseline and 12-month studies was quite small and also not different between the two groups: six MMF patients compared with five azathioprine patients. Although a posthoc end point, there was a significant benefit of MMF treatment compared with azathioprine in the mean change in lumen area from baseline to 12 months after transplant, with an increase of 0.33±0.30 mm2 in MMF patients compared with a decrease of 0.81±0.29 mm2 in the azathioprine patients (P=0.007;Table 4). The use of angiotensin-converting enzyme inhibitors and 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitors were similarly distributed between the two groups.

T4-16
Table 4:
ICUS measurements in the treated patients

Study medications and withdrawals. In the treated patients, the mean dose of maintenance prednisone was determined by protocol and was not different at 6 and 12 months after transplant in the MMF and azathioprine groups (10.9±0.4 and 8.0±0.3 mg/day versus 10.9±0.5 and 7.9±0.3 mg/day, respectively). Cyclosporine trough concentration levels were performed according to the assay used at each institution. The levels were grouped as below range, low-mid range, mid-high range, or above range for each assay and were similar between groups at 6 and 12 months after transplant. The average daily dose of study medications during the 12 months after transplant was 2.72 g/day for MMF patients and 1.92 mg/kg/day for azathioprine patients.

In the enrolled patients, withdrawal from the study was large and included 131 MMF patients (40.1%) and 138 azathioprine patients (42.7%). The reasons for withdrawal were similar in the two groups and are seen inTable 5. Many of the patients whose reasons for withdrawal were termed "other" were patients who voluntarily withdrew consent, who remained intubated, or who were otherwise unable to take oral medications. Among the treated patients, reasons for withdrawal were similar and included 93 MMF patients (32.2%) and 104 azathioprine patients (36.0%). The reasons for withdrawal were similar in both groups except there were more patients in the azathioprine group compared with the MMF group (six versus one) who withdrew from the study due to the need for medication prohibited by protocol.

T5-16
Table 5:
Reasons for withdrawal from the study in the enrolled- and treated-patient populations

Adverse events. Among the treated patients, the following adverse events were noted.

Side effects: The MMF patients experienced significantly more diarrhea(45.3% versus 34.3%; P=0.008) and esophagitis (7.3% versus 2.8%; P=0.021) during the study, but significantly more leukopenia was seen in the azathioprine patients (39.1% versus 30.4%;P=0.036). More hemoptysis was seen in the MMF group; however, the number of patients with such episodes were small and the episodes were categorized as mild, not requiring medications or medical evaluation(Table 6).

T6-16
Table 6:
Selected adverse events in the treated patients

Malignancy: The development of lymphoma or nonlymphoma malignancy was not different between the MMF and azathioprine groups (2 and 18 MMF patients versus 6 and 15 azathioprine patients, respectively) (Table 6).

Opportunistic infections: The MMF group had more opportunistic infections(53.3% versus 43.6%; P=0.025) compared with the azathioprine group. Specifically, the MMF group had more herpes simplex (20.8% versus 14.5%; P=0.063) and herpes zoster (10.7% versus 5.9%;P=0.049) compared with the azathioprine group. Cytomegalovirus infection (viremia/syndrome, tissue invasion) was not significantly different between the MMF and azathioprine groups (Table 6).

DISCUSSION

Previous studies in heart transplant patients have shown that MMF can reverse recurrent and refractory rejection (13,24,25). In addition, animal studies have demonstrated that MMF can decrease intimal proliferation in transplant models of allograft arteriopathy (26). Mechanistically, MMF selectively inhibits the de novo pathway for purine biosynthesis in activated lymphocytes, whereas azathioprine nonselectively inhibits the de novo and salvage pathways (27,28). An agent such as MMF with a narrow range of target cells in the immune system would be predicted to provide more optimal balance in immunosupression by inhibiting those cells involved in allograft rejection, yet allowing uninhibited cells to provide important defenses against infection. These studies provided the rationale to embark upon a prospectively randomized double-blind active-controlled trial to assess the efficacy of MMF in heart transplant recipients. This is the first such trial of maintenance immuno-suppression comparing any current or new immunosuppressive agent in the heart transplant recipients.

In this study, 72 of the 650 enrolled patients never received study drug. By chance, there was a higher mortality in the patients randomized to MMF in these 72 patients, with most of the difference being accounted for by patients who died within 10 days of surgery. This may have obscured the potential effects of MMF in the enrolled patients. Given the similarity of distribution of patients with respect to baseline characteristics in the 578 treated as well as the 650 enrolled patients and because inferences based on data from treated patients would be more clinically meaningful than those based on data from untreated patients (who subsequently received azathioprine), analysis of the treated-patient population was performed. This is consistent with recent opinions and examples in the clinical trial literature (29-32). Because the study was blinded, the decision to withdraw a patient could not have been influenced by treatment assignment, thus the 578 treated patients retain the randomization.

The treated-patient population demonstrated a significant (45%) reduction in mortality at 1 year in those patients who received MMF instead of azathioprine, in combination with cyclosporine and corticosteroids. The lower mortality in the MMF group seemed to be mostly due to a decrease in death related to the use of immunosupression (rejection, infection/sepsis). MMF may improve survival because it is either more potent or more selective in altering T- and B-cell function than azathioprine in heart transplant recipients. Alternatively, MMF may provide more synergy with concomitantly administered cyclosporine and/or corticosteroids than azathioprine. These differences may provide the basis for the demonstrated benefit of MMF in both the renal (15,33,34) and the presently described cardiac transplant populations.

Although there were no significant differences in the original primary end points relating to allograft rejection in the enrolled patients, there were significant differences seen in the treated patients. In the treated patients, the MMF group had more subjects who were rejection free (never treated for rejection) than the azathioprine group. Less rejection therapy in the MMF group likely accounts for the decreased number of deaths due to infection/sepsis. With respect to specific rejection grades, there was a trend for the MMF group to have fewer patients with rejection treated with OKT3 or ATG and fewer patients with rejection ≥ grade 3A (posthoc end point), suggesting that MMF decreases the severity of rejection episodes. MMF also decreased the development of rejection with hemodynamic compromise(posthoc end point), which has a high reported short-term mortality of approximately 40% as reported by a recent multicenter study(23). Similarly, in the present study, there was a 32%(12/38 patients) mortality at 12 months in the azathioprine group in contrast to no deaths (0/19 patients) in the MMF group in these patients with hemodynamically compromising rejection.

The present study demonstrated no angiographic or ICUS (measured by intimal thickness) benefit of MMF over azathioprine on allograft coronary artery disease at 1 year. The lack of difference between the MMF and azathioprine groups with respect to intimal thickness may be due to the short follow-up. The ICUS results revealed less baseline intimal thickness than a recent report of a trial of pravastatin in heart transplant patients, which also used morphometric analysis for the ICUS measurements(35). That study revealed twice the baseline maximal intimal thickness and intimal index compared with the current study. This suggests very little preexisting donor coronary artery disease and/or healthier donors in the present study patients. With this lower risk population, a larger patient population and/or more follow-up time may be needed to show a difference in the development of intimal thickness between the two groups.

The ICUS results revealed a significant benefit MMF over azathioprine a maintaining lumen area (posthoc end point) from baseline to 1 year. Shrinkage of the luminal area as seen in the azathioprine group is common in the arteries of cardiac allografts and is felt to be due to constrictive remodeling of the coronary artery vessels possibly due to a response to injury (36). The mechanism by which MMF may abrogate this constrictive remodeling process requires further study.

There were more reports of gastrointestinal symptoms in the MMF group, which were usually well tolerated and resolved with reduction in study medications. A previous report on 17 heart transplant patients continued on MMF therapy for a mean of 33 months found comparatively low levels of gastrointestinal difficulties, which were well tolerated with reduction in doses (14). The gastrointestinal side effects in the present study were less than those reported in the recent trials of MMF in kidney transplant recipients (15), despite the use of 40-50% higher MMF doses. MMF treatment was associated with more viral opportunistic infections (mostly herpes simplex and herpes zoster) and less rejection, suggestive of a greater immunosuppressive state. However, the immunosuppressive effect of MMF seemed to be selective, because a reduction in rejection was not associated with an increase in death from infection or an increase in lymphoma or other cancers.

A large withdrawal rate from both the MMF and azathioprine groups was seen in both the enrolled and treated patients. Approximately one third of the patients initially randomized to MMF were changed back to azathioprine during the first year after transplant. Many of these withdrawals may have been avoided with more experience with the drug's side effects or if intravenous MMF had been available to prevent the early withdrawals in those patients not able to take medications orally. This large withdrawal in the MMF group and the subsequent crossover of MMF-assigned patients to azathioprine may have decreased the observed efficacy in the MMF group, and therefore the current results may have underestimated the benefit potential of MMF. Autopsies were not routinely performed, which may have underestimated the amount and severity of allograft coronary artery disease, specifically in those patients who died before their first-year angiogram. Because the mortality rates were quite low and more patients died in the azathioprine group, it is unlikely that a bias toward MMF would be seen.

In conclusion, there was a significant reduction in first-year mortality(45% reduction) in patients treated with MMF (a subset of the enrolled group) compared with azathioprine, both in combination with cyclosporine and corticosteroids. The MMF group also demonstrated a reduction in the number of patients with any treated rejection, which included rejection requiring OKT3 or ATG and the posthoc end points of rejection ≥ grade 3A and rejection with hemodynamic compromise. In this study, side effects seemed to be tolerable (with more diarrhea and mild hemoptysis in the MMF group but more leukopenia in the azathioprine group), and there was no increase in malignancy in those patients treated with MMF. The MMF group did have more opportunistic infections, which included mostly herpes simplex and herpes zoster. There was a benefit of MMF over azathioprine on the posthoc end point of coronary artery lumen area at 1 year; however, longer study observation time may be necessary to show a difference in coronary artery intimal thickness between the two groups.

Acknowledgments. The members of the study group are (listed by center):

  • Alfred Hospital, Australia: Assoc. Professor Donald S. Esmore, MBBS, FRACS, FRCS(Edin CT); Dr. Peter Bergin, MBBS, FRACP; Dr. Meroula Richardson, MBBS, FRACP; Louise Macfarlane, RN; Bronwyn Levvey, RN.
  • Alton Oschner Medical Foundation: Frank W. Smart, MD; Hector O. Ventura, MD; Dwight Stapleton, MD; Mandeep Mehra, MD; Francesca Vial, RN; Olga Rosales.
  • Baylor College of Medicine: H. David Short III, MD; James B. Young, MD; Guillermo Torre, MD, PhD; Beth Cocanougher-Short, RN, BSN; Susan McRee, RN, BSN.
  • Brigham and Women's Hospital: Paul J. Hauptman, MD; Laura Gavrilles, BS; Caroline Collins, RN, BSN.
  • Columbia-Presbyterian Medical Center: Donna Mancini, MD; Keith Aaronson, MD; Ronald Drusin, MD; Stefano Ravalli, MD; Lisa Donchez, RN.
  • Deutsches Herzzentrum Berlin, Germany: Roland Hetzer, MD; Manfred Hummel, MD; Onnen Grauhan, MD.
  • Harefield Hospital, England: Dr. Nicholas R. Banner, FRCP; Professor Magdi Yacoug, FRCS.
  • Hopital Henri Mondor, France: Daniel Loisance, Valerie Baladier, Christophe Benrenutti.
  • Hospices Civils de Lyon Hospital, France: Professor Georges Dureau; Boissonnat Pascale, MD.
  • Kiel University Hospital, Germany: Stephan Hirt, MD; Angelina Costard-Jäckle, MD; Heidi Bottcher, MD; Max Pichlmeier, MD; Gustav Steinhoff, MD; Axel Haverich, MD.
  • Medical College of Wisconsin: Jeffrey D. Hosenpud, MD; Ron Siegel, MD; Michael P. Cinquegrani, MD.
  • Oregon Health Sciences University: Ranae M. Ratkovec, MD; Ray E. Hershberger, MD; Andrew C. Kao, MD; Douglas J. Norman, MD; Adnan Cobanoglu, MD; Mark J, Morton, MD.
  • Roche Pharmaceutical: Richard Mamelok, MD; David Ipe, MS; Henry Hulter, MD.
  • Rush Presbyterian-St. Luke's Medical Center: Maria Costanzo, MD; Alain Heroux, MD; Maryl Johnson, MD; Walter Kao, MD; Elaine Winkel, MD; Jeannie O'Sullivan, RN.
  • St. Louis University: Leslie Miller, MD; Thomas Donahue, MD; Thomas Wolford, MD; Mary Rawlings, RN; Mary Gilbert, RN; Lawrence Mcbride, MD.
  • St. Vincent's Hospital, Australia: Anne Keogh, MBBS, MD FRACP; Phillip Spratt, MBBS, FRACS, FRCP (EDIN); Peter Macdonald, MBBS, PhD, FRACP; Julie Mundy, MBBS (QLD), FRACS; Cate McCosker, BA; Annemarie Kaan, RN, CTNC.
  • Stanford University School of Medicine: Hannah Valantine, MD; Sharon Hunt, MD; Edward Stinson, MD; Joan Miller, MD.
  • Tampa General Hospital: Samuel S. Weinstein, MD; Raghavendra Vijayanagar, MD, FACS; Sjonne Mabbott, MS, ARNP; Mark Weston, MD.
  • Temple University School of Medicine: Howard Eisen, MD; Paula Pavelchak, RN; Valluvan Jeevanandam, MD; Terri Cianci-Hayes, RN; Alfred A. Bove, MD, PhD; Marie Droogan, RN, MS; Ileana Pina, MD.
  • University of Alabama at Birmingham: Robert C. Bourge, MD; James K. Kirklin, MD; David C. McGiffin, MD; Raymond L. Benza, MD; Cecelia Levio, RN; Beth Dean, RN; Charlotte Wheeler, BS; Richard Griffin, RN; Bonita Peoples, RN; Natali Wood, RN.
  • University of California, Los Angeles: Jon A. Kobashigawa, MD; Elaine Albanese, RN; Jaime D. Moriguchi, MD; Nobuyuki Kawata, MD; Alex Sabad, BA; Judith Cassem, BS; Hillel Laks, MD.
  • University of Colorado Health Sciences Center: JoAnn Lindenfeld, MD; William Abraham, MD; Michael Bristow, MD, PhD; Brian Lowes, MD; Eugene Wolfel, MD; Lawrence Zisman, MD.
  • University of Florida, Gainesville: Roger M. Mills, Jr., MD; Dana D. Leach, RN.
  • University of Michigan Medical Center: John M. Nicklas, MD; Francis D. Pagani, MD, PhD; Christopher B. Schooley, DO; G. Michael Deeb, MD; Angela R. Larkin.
  • University of Minnesota: Spencer H. Kubo, MD; Alan J. Bank, MD; Gary S. Francis, MD; Sara J. Shumway, MD; Kathleen Mullen, RN.
  • University of Utah Medical Center, LDS Hospital and The Salt Lake City Veterans Affairs Medical Center: Dale G. Renlund, MD; David O. Taylor, MD; Abdallah Kfoury, MD; Diane Dunn-Darger, RN; Beverly Campbell, RN; Marshal L. Edison, RN.
  • The university of Western Ontario, Canada: Alan H. Menkis, MD; F. Neal McKenzie, MD; Richard J. Novick, MD; Anne-Marie Powell, RN; Peter W. Pflugfelder, MD; William J. Kostuk, MD.
  • University of Wisconsin-Madison Medical School: Robert Mentzer, MD; William Miller, MD; Mary Michalski, RN; Ann Marie Hoffman, RN; Linda Jacobs, RN; Jan Yakey, RN; Charles Canver, MD; Robert Love, MD.
  • Vanderbilt Transplant Center: Stacy F. Davis, MD; Holley Cully, RN, BSN; William B. Hillegass, Jr., MD, MPH; Vijay Kumar Misra, MD; Paul Robert Myers, MD, PhD; John R. Wilson, MD; Greg Chapman, MD; Walter Merrill, MD; Geraldine Miller, MD; Stephen Dummer, MD; James B. Atkinson, MD; Richard N, Pierson III, MD; Xiaoming Zhao, MD.
  • Angiography Core Laboratory (Stanford University): Edwin L. Alderman, MD; Anne Schwarzkopf, BA; William Sanders, MSEE.
  • ICUS core Laboratory (University of California, Los Angeles): Jay Johnson, MD; Lianne Wener, BS; Jeffrey Carr, MD; Lawrence Yeatman, MD.

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