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Keywords:

  • CMV;
  • ganciclovir;
  • graft survival;
  • preemptive therapy;
  • prophylaxis;
  • renal transplantation

Abstract

  1. Top of page
  2. Abstract
  3. Introduction
  4. Materials and Methods
  5. Statistical Procedures
  6. Results
  7. Discussion
  8. Appendix
  9. Acknowledgments
  10. References

Oral ganciclovir prophylaxis and intravenous preemptive therapy are competitive approaches to prevent cytomegalovirus (CMV) disease after renal transplantation. This trial compared efficacy, safety and long-term graft outcome in 148 renal graft recipients randomized to ganciclovir prophylaxis (N = 74) or preemptive therapy (N = 74). Hierarchical testing revealed (i) patients with CMV infection had more severe periods of impaired graft function (creatinine clearancemax-min 25.0 ± 14.2 mL/min vs. 18.1 ± 12.5 mL/min for patients without CMV infection; p = 0.02),(ii) prophylaxis reduced CMV infection by 65% (13 vs. 33 patients; p < 0.0001) but (iii) creatinine clearance at 12 months was comparable for both regimes (54.0 ± 24.9 vs. 53.1 ± 23.7 mL/min; p = 0.92). No major safety issues were observed, and patient survival at 12 months was similar in both groups (5 deaths [6.8%] vs. 4 [5.4%], p = 1.0000). Prophylaxis significantly increased long-term graft survival 4 years posttransplant (92.2% vs. 78.3%; p = 0.0425) with a number needed to treat of 7.19. Patients with donor +/recipient + CMV serostatus had the lowest rate of graft loss following prophylaxis (0.0% vs. 26.8%; p = 0.0035). In conclusion, it appears that routine oral prophylaxis may improve long-term graft survival for most renal transplant patients. Preemptive therapy can be considered in low risk patients in combination with adequate CMV monitoring.


Introduction

  1. Top of page
  2. Abstract
  3. Introduction
  4. Materials and Methods
  5. Statistical Procedures
  6. Results
  7. Discussion
  8. Appendix
  9. Acknowledgments
  10. References

Cytomegalovirus (CMV) infection and disease is the major infectious complication in renal allograft recipients (1–5). CMV is known as an independent risk factor for acute rejection and is also suspected as a cause of chronic allograft dysfunction and subsequent late-onset graft loss (6). In addition, evidence from a recent study by Sagedal et al. suggests that CMV infection increases mortality and thereby renal graft loss (7). Numerous clinical studies (8–11), registry data (12) and guidelines (13,14) underline the need for effective CMV prevention using anti-viral agents for prophylaxis in patients who are at high risk for CMV infection and disease.

As an alternative to oral general prophylaxis with ganciclovir, preemptive therapy with intravenous ganciclovir can be considered for CMV prevention (15,16). Generally, intravenous preemptive therapy limits the occurrence of drug related side effects, because the exposure to the drug is limited to transplanted patients with proven CMV viremia (17). However, potential organ damage due to asymptomatic CMV infection may occur before preemptive therapy is initiated, even in the absence of CMV disease, and there may be further damage until viral load clearance can be completed. It is unclear if an asymptomatic CMV infection can directly or indirectly impair the renal graft and thereby decrease long-term graft and patient survival (7,18). Therefore, the use of prophylaxis versus preemptive therapy for preventing CMV infection following solid organ transplantation remains contentious, with clinicians arguing for and against the merits of both the approaches (9,15,16). As most CMV infection and disease occur during the first 3 months after renal allograft transplantation (7,12), the clinical impact of providing routine prophylaxis in all patients could be substantial.

This prospective randomized clinical trial was performed to determine if CMV prevention, based on oral ganciclovir prophylaxis, is superior compared to intravenous preemptive therapy. The trial assessed the efficacy of oral prophylaxis to prevent graft exposure to CMV and the impact of asymptomatic CMV viral load on graft function during a 12-month study phase. This trial also compares the effect of both treatment approaches on long-term graft survival; patients were observed in a follow-up phase for a further 3 years starting from day 100 after transplantation (in total 4 years plus 100 days).

Materials and Methods

  1. Top of page
  2. Abstract
  3. Introduction
  4. Materials and Methods
  5. Statistical Procedures
  6. Results
  7. Discussion
  8. Appendix
  9. Acknowledgments
  10. References

This prospective, randomized, multicenter, open-label clinical trial was performed at three transplant centers in Germany. The study protocol was approved by the ethics committees at Hannover Medical School and the University of Luebeck and was carried out according to the Helsinki Declaration and good clinical practice guidelines. The clinical trial was registered at ClinicalTrials.gov Identifier NCT 00373165.

Renal graft recipients were centrally randomized into either study group by phone (ClinIT AG, Freiburg, Germany). Patients were stratified by CMV serostatus and presence of anti-thymocyte globulin or OKT 3 induction therapy. All patients were adults, at risk for CMV disease with donor or recipient or both being positive CMV IgG serostatus, but currently negative for CMV viral load. Other eligibility criteria were an absolute neutrophil count >1000 cells/μL, thrombocytes >50 000 cells/μL prior to randomization and a standardized immunosuppressive combination therapy including a calcineurin inhibitor, mycophenolate mofetil and steroids. Patients were excluded if they were hypersensitive to ganciclovir or had a significant gastrointestinal disease that could affect drug absorption. Women who were pregnant, lactating or considered at risk of pregnancy, were not eligible. Every patient was informed about the nature and aim of the study, and written informed consent was obtained.

The prophylaxis group received 1000 mg ganciclovir peroral three times a day starting within 48 h after transplantation, until day 90. Temporary prophylaxis with 5 mg/kg body weight intravenous ganciclovir per day was initially allowed for patients who could not take oral medication. All patients were regularly monitored for CMV viral load in plasma using Cobas® Amplicor® CMV-Monitor (Roche Diagnostics GmbH, Mannheim, Germany), a quantitative CMV PCR test (19,20). Monitoring was performed once weekly at weeks 1–4, every 2 weeks at weeks 5–12, every month at weeks 13–24 and every 3 months at weeks 25–52 or additionally, as clinically indicated. All treatment decisions regarding the initiation and finalization of intravenous preemptive therapy were based on CMV-Monitor results. Patients in either group who were tested positive by CMV-Monitor (≥ 400 CMV DNA copies/mL) at any time after transplantation, received 5 mg/kg body weight intravenous ganciclovir preemptive therapy twice a day for at least 10 days, until CMV DNA was <100 copies/mL on two consecutive assessments. Thereafter, secondary prophylaxis was given using 1000 mg oral ganciclovir three times a day for at least 14 days. Every reoccurrence of CMV infection was treated with intravenous preemptive therapy followed by oral secondary prophylaxis. Patients with impaired renal function below 70 mL/min creatinine clearance received adjusted daily total doses of intravenous and oral ganciclovir according to the manufacturer's recommendations (50–69 mL/min = 1500 mg per oral/5.0 mg/kg IV; 25–59 mL/min = 1000 mg per oral/2.5 mg/kg IV; 10–24 mL/min = 750 mg per oral/1.25 mg/kg IV; <10 mL/min = 500 mg per oral, 3 times a week/1.25 mg/kg IV three times a week).

After 12 months, patients could complete a further written informed consent to participate in a long-term follow-up program. CMV manifestations were defined based on standardized criteria as latent CMV infection (asymptomatic CMV IgG positive serostatus), active CMV infection (asymptomatic CMV viral load proven by CMV-Monitor ≥400 CMV DNA copies/mL), symptomatic CMV disease as CMV syndrome (unspecific clinical symptoms and CMV viral load) and CMV tissue invasive disease (proven CMV-related organ dysfunction or failure and CMV viral load), respectively.

Statistical Procedures

  1. Top of page
  2. Abstract
  3. Introduction
  4. Materials and Methods
  5. Statistical Procedures
  6. Results
  7. Discussion
  8. Appendix
  9. Acknowledgments
  10. References

Sample size was based on the number of patients required to show a 20% difference in calculated creatinine clearance between treatment groups. For the primary endpoint analysis a hierarchical test procedure, including three steps, with an α-level of 5% for each step was used. Step 1: The absolute difference between the highest and the lowest level of creatinine clearance from 1 month after transplantation to the end of the 12-month study phase was compared for patients with and without active CMV infection. This was performed for all patients irrespective of their treatment group using the Wilcoxon rank-sum test. Step 2: The incidence of active CMV infection within the first 12 months was compared between the two treatment groups using Kaplan–Meier methods (21) and the log-rank test. Step 3: The creatinine clearance after 12 months was compared between treatment groups using the Wilcoxon rank-sum test. This stepwise procedure allowed the examination of the effect of CMV infection on graft function, to what extent prophylaxis prevented the onset of active CMV infection and if prophylaxis improved graft function at 12 months.

The intent-to-treat population of randomized and treated patients with at least one assessment, plus one CMV-Monitor result after baseline, was used for the primary endpoint analysis with the 3-step-hierachical test procedure. If at least one step of the hierarchical testing reached significance, secondary endpoints were prospectively analyzed as defined in the statistical analysis plan. Secondary endpoints were differences between study groups regarding the following parameters: the frequency of CMV infection, CMV syndromes or diseases within 12 months, patient survival (Fisher's exact test), the number of CMV related rehospitalizations (Wilcoxon rank-sum test), the time to graft loss both uncensored and censored for death (Kaplan-Meier methods and log-rank test) by treatment group and by patients with or without CMV infection. Sub analyses by risk subgroups (donor (D)/recipient (R) CMV serostatus) were also performed. For the analysis of graft loss, all remaining patients in the intent-to-treat population beyond 100 days post transplantation were included to prevent bias due to early complications after grafting (e.g. death and graft loss), similar to the analysis performed by Sagedal et al. (7). Patients who did not either reach the endpoint or complete the 4-year follow-up were censored.

Safety analysis was based primarily on the incidence of serious adverse events and the evaluation of myelotoxicity. Comparisons between treatment groups were made using the Fisher's exact test for the safety population, which included all randomized patients who took at least one dose of study medication.

Results

  1. Top of page
  2. Abstract
  3. Introduction
  4. Materials and Methods
  5. Statistical Procedures
  6. Results
  7. Discussion
  8. Appendix
  9. Acknowledgments
  10. References

Patient characteristics

Between November 2000 and September 2002, a total of 148 renal graft recipients were included into the study, 74 patients each in the prophylaxis and in the preemptive therapy group. All 148 patients were analyzed for safety. One hundred thirty-eight patients were eligible for the intent-to-treat population for the primary endpoint analysis—73 in the prophylaxis and 65 in the preemptive therapy group (10 patients were excluded as no CMV-Monitor test data were available after baseline). One hundred thirty patients were available for the 4-year analysis of graft loss from day 100—66 in the prophylaxis and 64 in the preemptive therapy group. Eight patients were lost during the first 100 days after transplantation primarily due to graft loss or death. The total number of early deaths or loss of transplant within 100 days was four deaths (2 events of heart failure, and 2 events of sepsis and liver failure) and two transplants lost (graft thrombosis, acute rejection) in the prophylaxis group and two deaths (both myocardial infarction) and four transplants lost (2 events of acute rejection, 1 event of graft embolism and 1 unknown reason) in the preemptive group. Demographic and background characteristics are summarized in Table 1. During the initial 12-month study period the mean (± SD) number of CMV-Monitor tests per patient in the intent-to-treat population (N = 138) was 12.51 ± 3.13 (N = 73) and 12.43 ± 3.24 (N = 65) for the prophylaxis and the preemptive therapy groups, respectively. The mean frequencies of CMV-Monitor tests per patient during the first 3 months after renal allograft transplantation were 8.51 ± 1.50 (N = 73) and 8.40 ± 1.49 (N = 65) for the prophylaxis and the preemptive therapy groups, respectively.

Table 1. Demographic and background characteristics (safety and ITT populations)
CharacteristicGeneral prophylaxis using oral ganciclovir Safety population (N = 74)Preemptive therapy using i.v. ganciclovir Safety population (N = 74)
  1. All plus/minus values are means ± SD.

  2. Blood pressure values = mmHg.; ITT = intent-to-treat; D+= donor CMV IgG positive; D−= donor CMV IgG negative; R+= recipient CMV IgG positive; R−= recipient CMV IgG negative; ATG = anti-thymocyte globulin.

Recipient age—years48.3 ± 12.450.9 ± 12.4
Donor age—years48.8 ± 16.148.6 ± 14.8
Male sex—no. (%)44 (59.5%)38 (51.3%)
Caucasian—no. (%)72 (97.3%)72 (97.3%)
Body weight—kg72.1 ± 14.874.6 ± 14.3
Systolic blood pressure147.8 ± 22.4145.2 ± 23.8
Diastolic blood pressure83.6 ± 14.182.6 ± 15.7
Stratification for ATG8 (10.8%)8 (10.8%)
Mean HLA-mismatch1.97 ± 1.332.65 ± 1.46
Treatment for rejection14 (18.9%)21 (28.4%)
Diabetes7 (9.5%)2 (2.7%)
Underlying causes of kidney disease—no. (%)
 Glomerulonephritis22 (29.8%)17 (23.0%)
 Pyelonephritis/interstitial nephritis3 (4.0%)3 (4.0%)
 Nephrosclerosis6 (8.1%)11 (14.8%)
 Diabetic glomerulosclerosis6 (8.1%)0 (0.0%)
 Polycystic kidney disease12 (16.2%)7 (9.5%)
 Others25 (33.8%)36 (48.7%)
 
CharacteristicITT population (N = 73)ITT population (N = 65)
 
Age—years48.5 ± 12.450.8 ± 12.5
Male sex—no. (%)43 (58.9%)35 (53.8%)
Body weight—kg72.1 ± 14.974.3 ± 14.1
Systolic blood pressure147.6 ± 22.5146.5 ± 23.8
Diastolic blood pressure83.5 ± 14.283.1 ± 16.2
Stratification for ATG8 (11.0%)7 (10.8%)
Mean HLA-Mismatch1.98 ± 1.332.56 ± 1.37
Treatment for rejection14 (19.2%)18 (27.7%)
Diabetes7 (9.6%)1 (1.5%)
CMV status donor/recipient—no. (%)
 D+/R+36 (49.3%)29 (44.6%)
 D+/R−22 (30.1%)22 (33.8%)
 D−/R+15 (20.6%)14 (21.6%)
 D−/R−0 (0.0%)0 (0.0%)

Twelve month graft function and efficacy of CMV prevention

In the intent-to-treat population (N = 138) decreases in graft function (creatinine clearancemax−min [mL/min] [mean ± SD]) were more severe in patients with CMV infection (25.0 ± 14.2 mL/min, N = 39) compared with patients without CMV infection (18.1 ± 12.5 mL/min, N = 87, p = 0.02). The incidence of CMV infection with prophylaxis (13/73) compared with preemptive therapy (33/65) was reduced by 65% over 12 months (p < 0.0001), and the mean ± SD maximum viral load was higher in the preemptive group (25 448.4 ± 45 912 CMV DNA copies/mL) than in the prophylaxis group (6837.7 ± 8998, p = 0.3172), but the difference was not significant. The mean ± SD duration of CMV infections was similar in both treatment groups at 34.82 ± 18.24 days in the prophylaxis group and 38.79 ± 26.61 in the preemptive therapy group. Prophylaxis was associated with a significantly longer mean time to first CMV infection (p < 0.0001) (Figure 1A) and only three patients experienced CMV infection within the first 3 months posttransplantation compared with 32 patients in the preemptive therapy group. For both study groups new CMV infections effectively stopped 180 days post transplantation. Comparable results within the treatment groups were seen in the D+/R−, D+/R+ and D−/R+ subgroups (Figures 1B–D). As expected from these results the proportion of patients requiring intravenous treatment during the first 12 months was substantially lower in the prophylaxis group (N = 13) than in the preemptive therapy group (N = 29) (17.8% vs. 44.6%, p < 0.0001), but for both groups the mean duration of intravenous treatment until negative viral load was nearly the same (prophylaxis 20.6 ± 10.4 days vs. preemptive therapy 21.8 ± 11.1 days, p = 0.9179) and there was no evidence for CMV strains resistant to ganciclovir or apparent treatment failures due to other reasons. CMV related rehospitalizations were lower in the prophylaxis (N = 5) compared with the preemptive therapy group (N = 12) (6.8% vs. 18.5%, p = 0.04). Hospitalizations were due to both CMV syndromes (0 vs. 5 patients (7.7%), p = 0.02) and tissue invasive diseases (4 (5.5%) vs. 12 patients (18.5%), p = 0.03) (affecting the bowel, kidney and lungs). The average time to CMV tissue invasive disease was 135.3 ± 12.4 days for prophylaxis and 39.4 ± 9.5 days for preemptive therapy (during the first 3 months after renal allograft transplantation, no events occurred for the prophylaxis group and 9 occurred for the preemptive therapy group). No coincidence of CMV infection and acute rejection episodes was found, and biopsy proven acute rejection rates were nearly the same in the prophylaxis (14 patients) and preemptive therapy group (18 patients) at month 12. Graft function based on creatinine clearance was not improved at 12 months for prophylaxis patients (N = 69) compared with preemptive therapy patients (N = 60) (54.0 ± 24.9 vs. 53.1 ± 23.7 mL/min, p = 0.92).

image

Figure 1. Kaplan–Meier curves showing time to first active CMV infection during 12 months after grafting. (A) CMV infection in the full intent-to-treat (ITT) population; (B) CMV infections in donor CMV IgG positive (D+) and recipient CMV IgG negative (R−) patients; (C) CMV infections in donor and recipient CMV IgG positive patients (D+/R+); (D) CMV infections in donor CMV IgG negative (D−) and recipient CMV IgG positive patients (R+). The p-values are from the log-rank test. IV-PT = intravenous preemptive therapy, O-GP = oral ganciclovir prophylaxis.

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Long-term graft function

Four-year data in patients available from the intent-to-treat population beyond 100 days post transplantation (N = 130) with CMV infection revealed a greater incidence of graft loss (uncensored for death) when compared with patients without CMV infection (a 25.0% failure rate [11 failed] vs. 9.0% [7 failed]; p = 0.0117; Figure 2A). This was also observed if patients were censored for death (17.0% [7 failed] with CMV infection compared with 6.7% [5 failed] without CMV infection [p = 0.0564; Figure 2C]), but statistical significance was not reached. This was explained by more deaths with adequate graft function in patients with CMV infection (p = 0.0143) (data not shown). Patients uncensored for death with a lower incidence of CMV infections due to prophylaxis had less graft loss compared with those in the preemptive group (7.8%[5 failed] vs. 21.7%[13 failed], p = 0.0425), Figure 2B, and again, statistical significance was not reached if patients were censored for death (with prophylaxis 4.8%[3 failed] compared to 16.1% [9 failed] in the preemptive group, p = 0.0621), Figure 2D. The number needed to treat to prevent one graft failure was 7.19 for prophylaxis uncensored for death. Similar findings showing a reduced graft loss with prophylaxis were observed at 2 and 3 years posttransplantation (data not shown). Analysis of failure rates according to donor and recipient CMV IgG serostatus (Figures 2A–D, Table inserts) also resulted in lower rates of graft loss for all subgroups with prophylaxis. Of specific clinical importance may be the failure rate in the most frequent D+/R+ subpopulation, with 0.0% graft loss in the prophylaxis group compared to 26.8% (7 failed) in the preemptive group (p = 0.0035), Figure 2B. This result was confirmed if D+/R+ patients were analyzed censored for death (0.0% graft loss after prophylaxis vs. 20.8%[5 failed] in the preemptive group [p = 0.0126]), Figure 2D.

image

Figure 2. Kaplan–Meier curves showing time to graft loss (uncensored and censored for death) during 4 years after grafting. (A) Graft loss according to presence or absence of CMV infection uncensored for death; (B) Graft loss according to treatment group uncensored for death; (C) Graft loss according to presence or absence of CMV infection censored for death; (D) Graft loss according to treatment group censored for death. Patients of the intent-to-treat population beyond 100 days posttransplantation are included (in total 4 years plus 100 days). The p-values are from the log-rank test. IV-PT = intravenous preemptive therapy; O-GP = oral ganciclovir prophylaxis.

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Tolerability

Safety data are presented in Table 2 for the safety population (N = 148). Leucopenia was observed more frequently in patients treated with ganciclovir prophylaxis (p = 0.0045) but neutropenia was not (p = 1.0000), whereas patients in the preemptive therapy group had a higher incidence of CMV related adverse events (15 vs. 33 events). The number of patients with a serious adverse event leading to withdrawal at 12 months was one patient with prophylaxis and three patients with preemptive therapy. Overall patient survival at 12 months was not different in both groups (p = 1.0000). As expected, the mean ± SD total dose and total days of treatment with ganciclovir were higher in the prophylaxis group (57 639 ± 26 615 mg and 105 ± 43.6 days) than in the preemptive therapy group (19 526 ± 22 649 mg and 52 ± 47.9 days). The mean ± SD total dose of secondary oral prophylaxis was 16 294 ± 22 473 mg in the preemptive therapy group.

Table 2. Overall safety at 12 months (safety population)
 Patients with a serious adverse eventp-Value
General prophylaxis using oral ganciclovirPreemptive therapy using intravenous ganciclovir
Nno. (%)Nno. (%)
  1. All p-values were obtained using the Fisher's exact test.

  2. Leucopoenia = <2 × 109/L; neutropenia = <1 × 109/L; thrombopenia = <50 × 109/L; anemia = hemoglobin <10 mg/dL.

All patients7442 (56.8)7439 (52.7)0.7413
Patients with myelotoxicity (serious adverse event)
 All patients
   Leucopenia7411 (14.9)741 (1.3)0.0045
   Neutropenia741 (1.4)740 (0.0)1.0000
   Thrombopenia743 (4.1)743 (4.1)1.0000
   Anemia74 8 (11.0)747 (9.5)1.0000
Patient survival
 Patients died745 (6.8)744 (5.4)1.0000

Discussion

  1. Top of page
  2. Abstract
  3. Introduction
  4. Materials and Methods
  5. Statistical Procedures
  6. Results
  7. Discussion
  8. Appendix
  9. Acknowledgments
  10. References

This study found that prophylactic oral ganciclovir therapy reduces the incidence of CMV infection and prolongs the time to first CMV infection, and that prevention of active CMV infection by prophylaxis may have a beneficial effect on long-term graft function and was associated with maintained renal graft survival 4 years after transplantation. This underlines the chronic nature of allograft dysfunction, which seemed to be prevented in patients with CMV prophylaxis; although no confirmatory histological data are available. Results were reproducible for the donor (D)/recipient (R) CMV IgG subgroups, and there was no evidence for a higher incidence of late-onset CMV infection or disease with prophylaxis compared to preemptive therapy, as recently discussed by Singh (16), or of ganciclovir resistance. The results also support recent data by Sagedal et al. (7), where early onset of CMV infection after transplantation was associated with reduced long-term graft survival and suggest that routine prevention of asymptomatic CMV infection during the first 3 months postrenal transplantation may have a significant positive impact on overall long-term clinical outcome. When deaths with a functioning graft were excluded from the long-term analysis of graft survival, statistical significance for prevention of graft loss by prophylaxis was not reached; although a very strong trend was still observed. For patients with adequate graft function, death was more common with CMV infection. Active CMV infection does appear to be a major contributor to chronic allograft dysfunction and possible mechanisms have been discussed elsewhere (12,22–24). Well-established methods to identify subclinical graft impairment following CMV infection or patients at risk of early graft loss, are currently unavailable. Preliminary proteomic analysis (25–28) based on collected urine samples was performed in the current study (data not shown). This indicated the potential for diagnostic protein patterns, which might reflect chronic graft dysfunction and subsequent transplant damage induced by active CMV infection. Supportive evidence for a possible protective effect of prophylaxis against CMV induced graft alterations was also observed (29). A confirmatory study is ongoing.

After ganciclovir prophylaxis was completed, the CMV infection rate in the D+/R− group was much higher than in all other subgroups indicating that prolonged prophylaxis, i.e. for 180 days, could be considered for these patients. Late onset CMV infections after 180 days post transplantation were few in either study group. D+/R+ patients had an over 50% CMV infection rate during the first 90 days in the preemptive therapy group which was markedly reduced below 10% with prophylaxis, and there was no subsequent graft loss observed 4 years post transplantation. Prophylaxis was also associated with a reduced incidence of rehospitalization and as graft survival was prolonged, ganciclovir prophylaxis may save costs for retransplantation and dialysis when compared to preemptive therapy and may further reduce graft shortage. A decreased rejection rate due to ganciclovir prophylaxis was not observed and was not an explanation for the reduced hospitalization. Also CMV triggered rejection episodes could not be identified as a possible explanation for the different graft failure rates, as rejection rates were comparable in both study groups. Overall tolerability was good for both treatment regimens—no patients died due to CMV disease, and there were no major safety issues. Withdrawals for serious adverse events were low overall and higher for patients in the preemptive therapy group.

In the current study a hierarchical testing was performed for the primary endpoint analysis regarding (i) impact of CMV infection on graft function, (ii) incidence of CMV infection and (iii) creatinine clearance in both study groups at month 12. From this hierarchical procedure, where the next step can only be analyzed if the preceding step is statistically significant, graft function measured by creatinine clearance was impaired significantly during active virus replication but graft function at 12 months was similar between the treatment groups. As statistical significance was not reached for the last step of the hierarchical test, this suggests that creatinine clearance may be a poor predictor for chronic allograft dysfunction (30,31). The hierarchical testing also revealed the validity of testing the secondary endpoints (including graft survival) as CMV infection did result in periods of poorer graft function and prophylaxis did reduce the incidence of CMV infection. Known limitations relating to open label studies were addressed using central treatment allocation (CTA) with electronic randomization procedures ensuring an equal chance of patients being assigned to either study group. Thus, bias in study group allocation by investigators was prevented. Quality assurance by CTA was completed with a standardized documentation process using electronic case report forms for data capture. As intensified immunosuppression could conceivably lead to a higher risk for CMV infection, patients were treated according to a standardized protocol and stratified by induction therapy. Patients were also stratified for CMV IgG donor/recipient serostatus. Donor and recipient characteristics (i.e. by age or by gender) were controlled by randomization; this was also true for underlying causes of renal disease or racial differences. It is unlikely that the differences seen in responses between the treatment groups could be related to demographic differences in patient groups. The immunosuppressive regimen used in the study was a commonly used combination therapy (including a calcineurin inhibitor, mycophenolate mofetil and steroids) and was the standard of care at the participating transplant centers. After completion of the 12-month study phase, immunosuppressive therapy was routinely continued and the immunosuppressive protocol maintained during long-term follow-up according to clinical needs. Therefore, changes in immunosuppressive therapy in the long-term were expected to be limited, and to have little impact on comparisons of graft survival between treatment groups. Every effort was made to control for compounding factors in the long-term analysis, but as patients were treated over extended periods it was not feasible to control for any undetermined factors which could influence graft survival.

In conclusion this trial is the first direct head-to-head comparison of oral ganciclovir CMV prophylaxis versus intravenous preemptive therapy and provides 4-year data indicating potential benefits of CMV prophylaxis on CMV infection and graft survival. The trial also provides further evidence supporting the use of universal prophylaxis to reduce CMV infection in recipients of solid organ transplants (32–35). A recent 12-month comparison of prophylactic versus preemptive oral therapy for CMV infection using valganciclovir (the ester prodrug of ganciclovir) in renal graft recipients (36) also revealed a reduced overall occurrence and delayed onset of CMV DNAemia with prophylaxis compared with preemptive therapy. Prophylaxis has also been suggested as beneficial in preventing both the direct and indirect effects of CMV infection in transplant recipients (37). Hence, routine oral prophylaxis may be considered for most renal transplant patients at risk for CMV infection (38). Patients at high risk (D+/R− CMV serostatus) may need either prolonged prophylaxis for complete prevention of CMV infection or CMV monitoring for preemptive therapy after prophylaxis has been completed. Preemptive therapy should only be considered in CMV low risk patients in combination with adequate CMV monitoring.

Appendix

  1. Top of page
  2. Abstract
  3. Introduction
  4. Materials and Methods
  5. Statistical Procedures
  6. Results
  7. Discussion
  8. Appendix
  9. Acknowledgments
  10. References

The study group was as follows:

Volker Kliem, Michael Burg (Lower Saxony Center for Nephrology, Hann. Muenden, Germany); Lutz Fricke, Thomas Wollbrink (University of Luebeck School of Medicine, Luebeck, Germany); Joerg Radermacher (Minden General Hospital, Minden, and Hannover Medical School, Hannover, Germany); Harald Mischak, Stefan Wittke (Mosaiques Diagnostics und Therapeutics AG, Hannover, Germany); Keith Dawes, Rolf-Rainer Dries (PRA International, Mannheim, Germany); Max Horneck, Martina Becker-Seemann (ClinIT AG, Freiburg, Germany); Waldemar Braun, Carmen Theek, Jenni Reifenberger, Stefan Loth (IFE Europe GmbH, Essen, Germany); Frank Rohde (Roche Pharma AG, Grenzach-Wyhlen, Germany).

Acknowledgments

  1. Top of page
  2. Abstract
  3. Introduction
  4. Materials and Methods
  5. Statistical Procedures
  6. Results
  7. Discussion
  8. Appendix
  9. Acknowledgments
  10. References

The authors would like to thank Waldemar Braun at IFE Europe GmbH for statistical advice.

The study was supported in part by Roche Pharma AG, Grenzach-Wyhlen, Germany. F. Rohde is an employee of Roche Pharma AG. V. Kliem, L. Fricke, M. Burg and J. Radermacher have received honoraria for providing advice to, and speaking for, Roche Pharma AG. All authors have attended advisory board and investigator meetings sponsored by Roche Pharma AG.

References

  1. Top of page
  2. Abstract
  3. Introduction
  4. Materials and Methods
  5. Statistical Procedures
  6. Results
  7. Discussion
  8. Appendix
  9. Acknowledgments
  10. References
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