Polymorphisms of Multidrug Resistance Gene (MDR1) and Cyclosporine Absorption in De Novo Renal Transplant Patients

BACKGROUND

Several single nucleotide polymorphisms (SNPs) in the multidrug resistance (MDR1) gene may play a role in the interindividual variation of cyclosporine A (CsA) absorption in renal transplant patients.

METHODS

An analysis of CsA absorption measured by the dose- and weight-adjusted 4 hr area under the time-concentration curve, AUC(0-4)/mg doseCsA/kg, was conducted on day 3 after transplantation, in 69 de novo renal transplant patients who were genotyped for MDR1 SNPs. Follow-up pharmacogenomic analysis at 1 month posttransplant was performed utilizing dose- and weight-adjusted 2-hour postdose CsA concentration (C2).

RESULTS

AUC(0-4)/mg doseCsA/kg was significantly higher (P=0.024) in (C/C)3435 individuals than in a grouped population of (C/T)3435 and (T/T)3435 patients on postoperative day 3. G2677T variants were not significantly correlated with CsA absorption (P=0.084). The number of C3435-G2677 haplotypes was the best predictor of CsA exposure. At 1 month posttransplant, no correlation was seen between MDR1 SNPs and CsA exposure. The frequency of wild-type variants for C3435T and G2677T were 61% and 77.6%, respectively. SNPs at G2677T and C3435T loci were found to be in linkage disequilibrium.

CONCLUSIONS

MDR1 polymorphisms are associated with differences in CsA exposure only in the first posttransplant week.

MDR1 C3435T polymorphisms correlate with cyclosporine levels in de novo renal recipients

BACKGROUND

Single nucleotide polymorphisms (SNPs) in the multidrug resistance (MDR1) gene correlate with the intestinal function of P-glycoprotein (PGP). PGP serves as a hydrophobic export pump that extrudes cyclosporine (CsA) across the luminal membrane thus preventing CsA absorption. These genetic variants may predict CsA exposure levels in the early posttransplantation period.

METHODS

CsA absorption profiles were established in 75 renal transplant patients using total daily dose and body weight adjusted 4-hour area under the time-concentration curve, AUC(0-4)/mg dose/kg body weight, on posttransplant day 3. These patients were subsequently genotyped for C3435T and G2677T polymorphisms using real-time polymerase chain reaction. An analysis was conducted to assess the independent impact of C3435T and G2677T SNPs on CsA bioavailability.

RESULTS

C3435T polymorphisms were found to be an independent predictor of CsA AUC(0-4)/mg dose/kg levels on postoperative day 3. An inverse correlation was found between the number of T alleles and AUC values such that every T allele was associated with an approximate 15% decrement in AUC(0-4)/mg dose/kg (P = .034). A similar nonsignificant trend was observed for G2677T polymorphisms.

CONCLUSIONS

MDR1 SNPs are correlated with CsA exposure in the early post-transplant period. Polymorphisms, in conjunction with other criteria, may become a useful tool to optimize initial drug dosing in renal transplantation.

Early recurrence of primary focal segmental glomerulosclerosis in an older cadaveric renal allograft recipient resistant to plasmapheresis

We report an unusual case of recurrent primary focal segmental glomerulosclerosis in an apparent low-risk cadaveric renal allograft recipient only 2 days after transplantation, who did not respond to repeated courses of plasmapheresis.

Early adequate mycophenolic acid exposure is associated with less rejection in kidney transplantation

This study examines the importance of early mycophenolic acid (MPA) exposure in the cyclosporine- and mycophenolate mofetil (MMF)-treated kidney transplant population. We prospectively evaluated 94 first solitary kidney transplant patients treated with cyclosporine (Neoral), MMF, and prednisone. Basiliximab was also given to 72 recipients. MPA exposure was measured by HPLC using a limited sampling estimate of 12 h area under the curve (AUC [0-12]) within the first week. Efficacy was determined by the occurrence of acute rejection and toxicity by the need to reduce MMF doses within the first 3 months post-transplantation. Acute rejection was observed in 14 (15%) and MMF toxicity in 27 (29%). Receiver operator curve analysis shows that MPA AUC [0-12] on day 3 was predictive of efficacy (c = 0.72, p = 0.007) but not toxicity (c = 0.57, p = 0.285). A separate analysis of only patients on basiliximab shows that the MPA AUC [0-12] on day 3 was also predictive of efficacy (c = 0.80, p = 0.01). Therefore early adequate exposure to MPA by day 3 is associated with low acute rejection but cannot predict toxicity. Adequate MPA exposure is also important with basiliximab induction therapy.

Potential clinical implications of substitution of generic cyclosporine formulations for cyclosporine microemulsion (Neoral) in transplant recipients

Cyclosporine (CsA) is a critical-dose drug for which a minor change in absorption can have important clinical implications. Generic formulations of CsA are becoming more widely available, but standard criteria for bioequivalence require only that a single study in healthy volunteers demonstrate that mean pharmacokinetic parameters fall within 80-125% of the mean values for Neoral, the reference formulation of CsA. However, CsA absorption is known to differ between healthy volunteers and transplant patients and between different types of transplant patients, such that standard bioequivalence testing may be inadequate to ensure interchangeability of CsA formulations in all patients. The limited available clinical evidence has shown that stable renal transplant patients receiving Neoral have a significant reduction in mean CsA trough level after transfer to the Cicloral formulation. Mean pharmacokinetic values have been reported as equivalent following transfer to Gengraft in one study, but mean CsA trough fell and mean serum creatinine rose significantly in a separate trial. The only clinical outcomes data available are from a retrospective study of de novo renal transplant patients, which reported a significantly higher incidence of biopsy-proven acute rejection in patents receiving Gengraf versus Neoral (39% versus 25%, P<0.05). Until robust clinical data demonstrate that different formulations of CsA are interchangeable, it is advisable to prescribe CsA by brand, and any transfer to a different CsA formulation should be undertaken with close supervision and only at the direction of the transplant physician.

Therapeutic monitoring of cyclosporine in kidney transplantation: the Halifax experience

Appropriate dosing of an immunosuppressive agent is critical to its efficacy and tolerability. Finding a simple and effective method of monitoring cyclosporine (CsA/CyA) has been formidable despite a long history of widespread usage. Earlier reports linked CsA dosing to trough levels (C0), whereas later more elaborate systems have evaluated efficacy linked to 12-hour area-under-the-curve (AUC(0-12)) as a measure of total drug exposure. Recent work done at our center and elsewhere has shown that the 2-hour postdose concentration (C2) to be simple and more effective than the C0 or the AUC. With C2 monitoring as a guide to CsA dosing, acute rejection (AR) and nephrotoxicity (NT) can be effectively reduced. Furthermore, absorption profile as per C2 levels further emphasizes the importance of achieving the targeted peak concentration in the first week of transplantation. The C2 concentration strategy is discussed in light of newer induction agents and other immunosuppression.

An economic model of 2-hour post-dose ciclosporin monitoring in renal transplantation

BACKGROUND

Monitoring of microemulsion ciclosporin (cyclosporine; Neoral) by 2-hour post-dose drug concentrations (C2) is an accurate measure of ciclosporin absorption efficiency and exposure, and appears superior to trough (C0) monitoring for prediction of rejection risk. A predictive decision model was used to determine if this approach also reduces total treatment costs in the first 12 months after renal transplantation.

METHODS

Parameter estimates for key clinical events were derived from the literature and from prospective pharmacokinetic studies comprising 234 adult HLA-non-identical renal graft recipients at seven Canadian centres. Patients were treated with microemulsion ciclosporin (Neoral), corticosteroids and azathioprine or mycophenolate mofetil. Using the perspective of the Canadian healthcare provider, total treatment costs for the C2 versus the C0 strategy were modelled over 12 months, and then remodelled using conservative estimates to extend the timeframe to 5 years. Health resources were valued in 1999 Canadian dollars.

RESULTS

The incidence of acute rejection was estimated to be 25% at 1 year in patients monitored by C0 and 18% in those monitored by C2. Patient survival was considered to be independent of monitoring strategy, and graft loss was predicted to be 1.4% lower in the C2 group. The studies suggested no important differences in comorbidity and the costs of C0 and C2 monitoring and ambulatory-based adverse events were held equivalent. Using these inputs, the average cost per patient for the first year post-transplant was Can dollars 46,857 for C0 monitoring and Can dollars 45,306 for C2 monitoring, rising to Can dollars 146,879 and Can dollars 142,569 after 5 years. The predicted cost for initial hospitalisation was Can dollars 11,280 for C0 and Can dollars 10,806 for C2 monitoring. The cost of maintenance immunosuppressive drug use, graft loss and dialysis was Can dollars 19,098 in the C0 group and Can dollars 18,612 in the C2 group, while acute rejection treatment costs were Can dollars 2169 and Can dollars 1577, respectively. An additional Can dollars 14,310 was consumed by other events, including repeat hospitalisation, for each group. Sensitivity analysis indicated that the most influential parameters affecting savings due to C2 monitoring were a reduction in the duration of initial and follow-up hospitalisations and reduced risks of acute rejection and subsequent graft loss.

CONCLUSIONS

Compared with traditional trough concentration monitoring, ciclosporin monitoring at 2 hours post-dose produced a predicted saving of Can dollars 1551 during the first year after renal transplant. Although modelling assumptions become more restrictive over time, this projection allows a preliminary assessment of the long-term economic impact of the routine use of C2 monitoring.

Tacrolimus monitoring by simplified sparse sampling under the concentration time curve

The purpose of this study was to determine which tacrolimus pharmacokinetic parameters best predicted efficacy in kidney transplantation. Blood tacrolimus levels at 0, 1, 2, 3, and 4 hours postdose were measured in 28 kidney transplants. All received tacrolimus-based triple-drug therapy with mychophenolate mofetil and prednisone. Associations between blood concentrations at each sampling time point and the area under the curve (AUC) 0-4 were measured by Pearson's correlation coefficients. Tacrolimus dosing was based on C0 not AUC. AUC and blood concentrations at each sampling time were retrospectively compared with C0 as predictor of acute rejection and nephrotoxicity. Although tacrolimus C0 correlated with AUC0-4 (r =.86), correlations were higher with C2 and C3 (r =.96 and r =.94, respectively). C0 levels were not significantly different in six patients with acute rejection and 23 patients without. There was a trend toward lower tacrolimus C3 in patients with AR than without AR (P =.06). C2 and C3 correlate better with AUC0-4 than C0. Early tacrolimus C3 levels may be a better than C0 as a predictor of efficacy.

Importance of peak PRA in predicting the kidney transplant survival in highly sensitized patients

Do patients with high historic peak panel-reactive antibodies (PRA) remain high risk if their PRA levels fall before transplantation? We examined retrospectively 406 first and repeat kidney recipients with a peak PRA of >50%, who were transplanted from our center between January 1990 and December 2001. Univariate analysis by log-rank test was performed for variables that affect graft survival. The factors tested included current PRA, peak PRA, difference between peak and current PRA (DeltaPRA), HLA mismatch, gender, age, transplant number, and donor source. Receiver operator characteristic curves (ROC) were generated to obtain the best cutpoints for current PRA and DeltaPRA. Current PRA (P < .0001), peak PRA (P = .0004), and DeltaPRA (P = .0015) were significant predictors by univariate analysis. However, in a multivariate model, peak PRA was not significant. Current PRA (P < .0001) was significantly associated with graft survival, while DeltaPRA showed a strong trend to significance (P = .05). Current PRA of <26% and DeltaPRA of >37% were the best cutpoints for separating good and poor outcomes. This study shows that current PRA and DeltaPRA impact on graft survival in highly sensitized (>50%) patients. Sensitized patients with peak PRA >50% who subsequently have a drop in PRA to <26% are at lower risk of graft loss than those with a persistently high PRA. A fall in peak PRA of >37% at the time of transplant appears to be of benefit only in those patients who achieve a current PRA of <26%.

Basiliximab widens the therapeutic window for AUC-monitored neoral therapy early after kidney transplantation

Early adequate cyclosporine exposure has been shown to predict low acute rejection. Recently basiliximab induction has been added to immunosuppressive regimens to further reduce rejection. The aim of this study was to determine the importance of achieving the early cyclosporine therapeutic threshold with basiliximab induction. A retrospective analysis of first cadaver and nonidentical living donor transplant recipients treated with or without basiliximab induction was performed. All patients (n = 170) received neoral, mycophenolate mofetil, and prednisone. The cyclosporine absorption profile was measured on day 3. Adequate cyclosporine exposure was defined as area under the curve (AUC) 0-4: >4400 microg x h/L at day 3. The primary outcome was acute rejection (AR) within the first 6 month. In the no basiliximab (control) group, AR occurred in 22% (17/78) of recipients and was strongly associated with low cyclosporine exposure on day 3. AR occurred in 39% (9/23) with cyclosporine AUC0-4 < 4400 microg x h/L compared with 15% (8/55) with AUC0-4 > 4400 microg x h/L (P =.016). In the basiliximab group, AR occurred in only 9% (8/92) of recipients and did not correlate with cyclosporine exposure. AR occurred in 8% (2/24) with cyclosporine AUC0-4 < 4400 microg x h/L compared with 9% (6/68) with AUC0-4 > 4400 microg x h/L (P =.94). Achieving cyclosporine therapeutic targets by day 3 may not be required when anti-IL2 induction is used.

A pharmacokinetic and clinical review of the potential clinical impact of using different formulations of cyclosporin A. Berlin, Germany, November 19, 2001

A meeting of 14 transplant and pharmacokinetic specialists from Europe and North America was convened in November 2001 to evaluate scientific and clinical data regarding the use of different formulations of cyclosporin A (CsA). The following consensus was achieved. (1) CsA is a critical-dose drug with a narrow therapeutic window. Clinical outcomes after transplantation are affected by the pharmacokinetic properties of CsA, particularly by its bioavailability, and by intrapatient variability in CsA exposure. (2) Standard bioequivalence criteria do not address differences in CsA pharmacokinetics between transplant recipients and healthy volunteers, or between subpopulations of transplant recipients. (3) In some circumstances, currently available formulations of CsA that meet standard bioequivalence criteria are likely to be nonequivalent with respect to pharmacokinetic characteristics. (4) The choice of CsA formulation can affect the short- and long-term clinical outcome. Currently, there is a lack of clinical comparisons between generic CsA formulations and the Neoral formulation (Novartis Pharmaceuticals Corporation, East Hanover, New Jersey). Initial retrospective data from the Collaborative Transplant Study suggest that use of generic CsA formulations may result in reduced graft survival at 1 year. (5) Management of transplant recipients by monitoring Neoral concentrations 2 hours after dosing (C(2)) reduces the incidence and severity of acute rejection compared with monitoring of trough concentrations with no increase in toxicity. C(2) monitoring has been developed based on the pharmacokinetics of Neoral only and has not been evaluated or validated for generic formulations of CsA. (6) The major costs of care after transplantation relate to the management of poor clinical outcomes and toxicity. CsA formulations with different pharmacokinetic properties may be associated with varying clinical outcomes, which would be expected to affect total health care costs. (7) The transplant physician is responsible for selecting immunosuppressive agents and formulations for his or her patients. Any switch between CsA formulations in a particular patient should take place only in a controlled setting with adequate pharmacokinetic monitoring.

Adequate early cyclosporin exposure is critical to prevent renal allograft rejection: patients monitored by absorption profiling

This study used receiver operating characteristic analysis to investigate the properties of area under the concentration-time curve during the first 4h after cyclosporin-microemulsion dosing (AUC0-4) and cyclosporin (CyA) levels immediately before and at 2 and 3h after dosing (C0, C2 and C3) to predict the risk of biopsy-proven acute rejection (AR) at 6 months. Ninety-eight kidney transplant recipients treated with CyA-microemulsion-based triple therapy immunosuppression were studied on post-transplant days 3, 5, and 7, and at increasing intervals thereafter. The most sensitive and specific predictor of AR was AUC0-4. Of the single time-point measurements, the measurement properties of C2 were closest to those of AUC0-4, and superior to those of C3. The relationship between C0 and subsequent AR was weak and did not reach statistical significance. On day 3, CyA AUC0-4 > or = 4,400 ng.h/mL and C2 > or = 1,700 ng/mL were each associated with a 92% negative predictive value for rejection in the first 6months. Pharmacokinetic measurements on or after day 5, and measurements on day 3 in patients with delayed graft function, were not predictive of AR. Adequate exposure within the first 3days post transplantation may be critically important in preventing subsequent rejection.

Systematic finger guided transrectal needle biopsies of the prostate--alternative to TRUS guided biopsies in clinical practice

OBJECTIVE

To prospectively evaluate the efficacy of a Systematic Finger Guided (SFG) approach to transrectal Prostate Needle Biopsy (PNB).

PATIENTS AND METHODS

One hundred and eighty-nine sets of SFG PNB were performed on 145 men. At least four biopsy cores were taken systematically from apex to base on each side of the prostate, including suspicious areas if present. The SFG experience was compared to a literature cohort and to 14 patients who had both SFG and TRUS guided PNB.

RESULTS

Of 111 SFG biopsy sets taken from 88 men with suspicious DRE, 53% were positive; 25%, 43% and 84% of men had a PSA of 0-4, 4.1-10 and >10 ng/ml respectively. With benign DRE's, positive biopsies were seen in 22% and 28% of those with a PSA 4.1-10 and >10 ng/ml respectively. Of 22 patients with two or more sets of SFG PNB's, 11 (50%) were positive on repeat PNB. Of the 14 patients with a mix of TRUS and SFG PNB's, six were concordant, four were positive on SFG only, and one on TRUS only (p=n.s.).

CONCLUSION

Results of SFG PNB's and TRUS PNB's are equivalent in patients with and without suspicious prostates on DRE, probably due to the systematic nature of the sampling and number of the samples taken.

Kidney transplantation in children with urinary diversion or bladder augmentation

PURPOSE

Urinary tract anomalies or dysfunction leaves the bladder unsuitable for urine drainage in a significant proportion of children presenting for kidney transplantation. We reviewed a multi-institutional experience to determine the ramifications of kidney transplantation in children with bladder augmentation or urinary diversion.

MATERIALS AND METHODS

During a 28-year period 18 boys and 12 girls 1.7 to 18 years old (mean age 12.1) received 31 kidney transplants. Cause of end stage renal disease was renal dysplasia in 8 cases, posterior urethral valves in 5, obstructive uropathy in 5, neurogenic bladder/chronic pyelonephritis in 4, spina bifida/chronic pyelonephritis in 3, prune belly syndrome in 3 and reflux in 2.

RESULTS

Of the patients 17 had augmented bladder (ileum 9, ureter 5, sigmoid 2 and stomach 1), 12 had incontinent urinary conduits (8 ileum, 6 colon) and 1 had a continent urinary reservoir. Surgical complications included 1 case each of stomal stenosis, stomal prolapse, renal artery stenosis, urine leak, enterovesical fistula and wound dehiscence. Medical complications included urinary tract infection in 21 cases and metabolic acidosis in 5. A bladder stone developed in 1 patient. There was no correlation between the incidence of symptomatic urinary tract infections and type of urinary drainage. Acidosis was more common in patients with augmented bladder (4 of 17 versus 1 of 14) but there was no correlation between the bowel segment used and the occurrence of acidosis. Graft survival was 90% at 1 year, 78% at 5 years and 60% at 10 years. Etiology of graft loss included chronic rejection in 6 cases, noncompliance in 4 and acute rejection in 1. There were no deaths.

CONCLUSIONS

Drainage of transplanted kidneys into an augmented bladder or urinary conduit is an appropriate management strategy when the native bladder is unsuitable or absent. Patients with kidney transplants drained into augmented bladder or urinary conduit are at increased risk for urine infection. Graft survival is not adversely affected compared to historical controls when a kidney transplant is drained into a urinary conduit or augmented bladder.

Approaching the therapeutic window for cyclosporine in kidney transplantation: a prospective study

Neoral dosing is traditionally based on cyclosporine (CyA) trough levels (C(0)). Four-h area under the curve (AUC(0-4)) for Neoral in the early posttransplantation period was shown previously to have a better correlation to acute rejection (AR) and CyA nephrotoxicity (CyANT), compared with C(0). An AUC(0-4) range of 4400 to 5500 microg/h per L during the first week was associated with the lowest AR and CyANT. This article describes a prospective study to assess the feasibility, safety, and efficacy of dosing Neoral solely by AUC(0-4) monitoring, regardless of C(0), in the first 3 mo after kidney transplantation. Fifty-nine kidney transplant recipients received Neoral-based triple immunosuppression. AUC(0-4) was measured on days 3, 5, 7, 10, and 14 and weeks 3, 4, 6, and 8, then monthly. Target AUC(0-4) was 4400 to 5500 microg/h per L. Dose was adjusted by percentage difference from target AUC(0-4). Ninety-four percent of AUC were performed on the scheduled day or close to it. No patients had CyANT while AUC(0-4) was in target range. Four patients had reversible CyANT with AUC(0-4) > 5500. Only 1 of 33 patients (3%) who achieved and maintained AUC(0-4) > 4400 by day 3 posttransplantation had AR, whereas 10 of 22 (45%) of those with day 3 to 5 AUC(0-4) < 4400 had AR (P: = 0.0002). In logistic regression analysis, higher early AUC(0-4) was the only significant variable associated with lower serum creatinine at 3 mo. Neoral dose monitoring by AUC(0-4) is a potentially valuable tool for optimizing Neoral immunosuppression. Attainment of a target range of 4400 to 5500 microg/h per L for AUC(0-4) early after transplantation has been demonstrated to reduce significantly the risk of AR and CyANT.

Is routine ureteric stenting needed in kidney transplantation? A randomized trial

BACKGROUND

Whether routine ureteric stenting in low-urological-risk patients reduces the risk of urological complications in kidney transplantation is not established.

METHODS

Eligible patients were recipients of single-organ renal transplants with normal lower urinary tracts. Patients were randomized intraoperatively to receive either routine stenting or stenting only in the event of technical difficulties with the anastomosis. All patients underwent Lich-Gregoire ureteroneocystostomy.

RESULTS

Between June 1994 and December 1997, 331 kidney transplants were performed at a single center, 305 patients were eligible, and 280 patients were enrolled and randomized. Donor and recipient age, sex, donor source, whether first or subsequent grafts, ureteric length, native renal disease, and immunosuppression were similar in each group. In the no-routine-stenting group 6 of 137 patients (4.4%) received stents after randomization for intraoperative events that in the surgeon's opinion required use of a stent. In an intention-to-treat analysis there was no difference between groups in the primary outcome cluster of obstruction or leak [routine stenting 5 of 143 (3.5%) vs. no routine stenting 9 of 137 (6.6%); P=0.23], or in either of these complications analyzed separately. All urological complications were successfully managed without major morbidity. Living donor organs and shorter ureteric length (after trimming) were univariate risk factors for leaks, although increasing donor age was associated with obstruction.

CONCLUSIONS

Routine ureteric stenting is unnecessary in kidney transplantation in patients at low risk for urological complications. Careful surgical technique with selective stenting of problematic anastomoses yields similar results.

Impact of absorption profiling on efficacy and safety of cyclosporin therapy in transplant recipients

The optimisation of cyclosporin therapy remains a challenge because of the very narrow therapeutic window and the highly variable pharmacokinetics of the drug. Therefore, there has been a concerted effort in the clinical transplant community to explore and test cyclosporin monitoring tools and techniques that will allow blood concentrations of cyclosporin to be maintained within the narrow therapeutic window in order to maximise efficacy and minimise toxicity. Absorption profiling is a simple and accurate technique for adjusting dosages of cyclosporin microemulsion that utilises an estimation of the rate and extent of cyclosporin absorption in order to optimise immunosuppression in the individual patient. Two estimation tools in particular are an abbreviated area under the concentration-time curve (AUC) for the first 4 hours postdose and a single sampling point at 2 hours postdose. These 2 monitoring strategies have not only been validated as an accurate estimation of cyclosporin bioavailability but have been demonstrated to significantly improve clinical outcomes in patients compared with traditional trough concentration monitoring. The evidence presented in this review demonstrates that absorption profiling results in the following clinical benefits compared with trough concentration monitoring: (i) reduced incidence of acute rejection; (ii) reduced severity of rejection episodes; (iii) reduced nephrotoxicity; and (iv) a rational basis for dosage adjustments. The optimisation of immunosuppressive therapy continues to be a major priority in the management of the organ transplant recipient. Absorption profiling is a sensitive and practical approach for optimising the dosage of cyclosporin microemulsion, and can further extend the benefits of cyclosporin immunosuppression in the individual patient.

Progress in renal transplantation

PURPOSE

The improvements in renal transplantation over the last 10 years have been one of the great success stories in medicine. We reviewed these successes with a focus on the following: changes in demographics of donors and recipients in Canada, the benefits of new immunosuppressive regimes and the efforts to minimize their toxicity and finally, our understanding of measures to circumvent chronic rejection.

MATERIALS AND METHODS

A review of current transplantation literature was performed and pertinent data presented. As well, information from the Canadian Organ Replacement Register was selected to provide an overview of changes in renal transplantation in Canada.

RESULTS

Despite the stable rate of transplantation in Canada, the number of new patients starting dialysis each year roughly equals the entire national renal transplant waiting list. These patients are older and have more complex co-morbidities mandating prudent use of immunosuppression so as to minimize toxicity. Standard triple therapy consists of a calcineurin inhibitor, an antimetabolite and corticosteroids. Antibody therapy is indicated in sensitized recipients and newer monoclonal humanized antibodies offer less toxicity. Nonspecific therapies are less favorable due to unwanted side effects and we can now identify subsets of patients who are most likely to benefit from specific therapy. Newer non-nephrotoxic agents hold promise for future regimens. However a paucity of large, multicenter, randomized trials, tested against standard protocols, limits their current indications. Many immunologic and non-immunologic factors influence the outcome of renal transplantation and play a role in the development in acute and chronic rejection.

CONCLUSIONS

The challenges of renal transplantation over the next 10 years are: 1) in the development of specific therapies that can be altered according to patient co-morbidities and other factors influencing outcome; 2) minimizing toxicity; 3) preventing chronic rejection; and 4) improving our national organ donation network.

Effect of recipient sensitization (peak PRA) on graft outcome in haploidentical living related kidney transplants

OBJECTIVE

To evaluate the influence of pre-transplant recipient sensitization on the outcome of 1-haploidentical live related donor (LRD) kidney transplants.

METHOD

We reviewed 141 consecutive cyclosporine-treated adult haploidentical first transplants for which panel reactive antibody (PRA) levels were available. Patients were divided into three groups according to their peak PRA levels: group I, PRA = 0 (n = 97); group II, PRA = 1-50% (n = 24); and group III, PRA = 51-100% (n = 20).

RESULTS

Differences in PRA were associated with significant differences in short- and longer-term graft survival, unrelated to patient survival. Graft survival at 1, 3, and 5 yr was only 74, 40, and 27% in group III, compared to 92, 87, and 52% in group II, and 96, 91, and 85% in group I (p < 0.001). Increasing PRA was associated with shorter time-to-graft failure. In group III, 20% lost their transplant from acute rejection in the first 6 months, versus 4% in group II and 3% in group I (p < 0.01). Graft survival in group II diverged from that of group I only after 3 yr, due to an increase in loss from chronic rejection. Hospitalization was longer in group III, in association with a significantly higher incidence of acute rejection during the first 3 months after transplantation (p < 0.02). Serum creatinine was higher in sensitized than nonsensitized patients at all time points.

CONCLUSIONS

Sensitization has a significant negative impact on the outcome of haploidentical LRD kidney transplants. Sensitized potential recipients and their potential donors should be aware of this in arriving at informed decision-making for transplantation. These patients may benefit from more sensitive cross-match testing, more intense or more novel immunosuppression, or immunomodulation to modify their immune responsiveness.

Neoral use in the renal transplant recipient

This review and critical analysis of current trends of immunosuppression management in pediatric transplantation provides evidence and support for the continued role of Neoral as an indispensable part of immunosuppressive protocols. CyA formulation influences clinical outcomes such as acute rejection, as confirmed by several multicenter studies. The CyA microemulsion formulation reduces pharmacokinetic variability and its consequent impact on outcomes over the long term. An advanced TDM strategy can improve the effectiveness and safety of immunosuppression in both de novo and maintenance renal transplant patients. There are potential risks resulting from CyA withdrawal strategies. Neoral is an indispensable part of combination protocols in renal transplantation.

Perinephric abscess presenting as chronic diarrhea

Perinephric abscess is an uncommon diagnosis with a variable presentation and high mortality. We report an unusual case of a patient with a perinephric abscess who presented with chronic diarrhea and weight loss.

Is 3-hour cyclosporine blood level superior to trough level in early post-renal transplantation period?

PURPOSE

Cyclosporine dose is traditionally based on trough blood levels. Cyclosporine trough blood level correlates poorly with acute rejection and cyclosporine nephrotoxicity after renal transplantation. We determined whether cyclosporine blood level at any other time point is superior to cyclosporine trough blood level as a predictor of acute rejection and cyclosporine nephrotoxicity.

MATERIALS AND METHODS

Cyclosporine blood level was measured before (trough), and 1, 2, 3 and 4 hours after the dose in 156 initial renal transplant cases 2 to 4 days after the initiation of cyclosporine micro-emulsion formula administration. The cylosporine micro-emulsion dose was based on cyclosporine trough blood level targeting 250 to 400 microg./l.

RESULTS

Regression analysis revealed that only delayed graft function (p = 0.007) and cyclosporine blood level after 3 hours (p = 0.008) predicted acute rejection. Mean cyclosporine trough blood level plus or minus standard error was not significantly different in patients with and without acute rejection (293+/-21 versus 294+/-11 microg./l.). Mean cyclosporine blood level after 3 hours was significantly lower in patients with acute rejection (1,156+/-90 versus 1,421+/-50, p = 0.008). Cases were divided into tertiles at levels after 3 hours (1,100 and 1,500 microg./l.). The group in which the level after 3 hours was less than 1,100 microg./l. had the highest acute rejection rate (22 of 50 patients, 44%) and a cyclosporine nephrotoxicity rate of 13% (7 of 52 patients). The group in which the level after 3 hours was 1,100 to 1,500 microg./l. had the lowest acute rejection rate (5 of 46 patients, 11%) without increased cyclosporine nephrotoxicity (7 of 52 patients, 13%). A level after 3 hours of greater than 1,500 microg./l. was associated with a rejection rate of 15% (7 of 47 patients) but significantly higher cyclosporine nephrotoxicity (16 of 52 patients, 30%).

CONCLUSIONS

Cyclosporine blood level after 3 hours in the early post-transplantation period is associated with acute rejection and cyclosporine nephrotoxicity. A cyclosporine blood level range after 3 hours of 1,100 to 1,500 microg./l. is associated with an optimal outcome. Our data suggest that cyclosporine blood level after 3 hours may represent a better method of monitoring cyclosporine micro-emulsion dose than cyclosporine trough blood level. This hypothesis must be further studied in randomized trials.

Neoral monitoring by simplified sparse sampling area under the concentration-time curve: its relationship to acute rejection and cyclosporine nephrotoxicity early after kidney transplantation

BACKGROUND

Cyclosporine (CsA) dosing is traditionally based on trough blood levels (C0) rather than area under the concentration-time curve (AUC), although AUC correlates better with posttransplantation clinical events. For Neoral, AUC based on limited sampling correlates closely with full 12-hr AUC. The purpose of our study was to correlate C0 with AUC based on CsA levels at 0, 1, 2, 3, and 4 hr after dose (PK0-4) and to compare this AUC with C0 in predicting acute rejection (AR) and acute cyclosporine nephrotoxicity (CsANT) in de novo first kidney transplant patients.

METHODS

PK0-4 was done 2-4 days after starting Neoral for 156 patients. All received CsA-based triple-drug immunosuppression without antibody induction. AUC was calculated as projected 12-hr (AUC0-12) and actual 4-hr (AUC0-4) from the PK0-4 using the parallel trapezoid rule. Neoral dosing was based on C0 not AUC. AUC was retrospectively compared with C0 as a predictor of AR and CsANT during the first 90 days.

RESULTS

C0 correlated poorly with AUC0-12 and AUC0-4 (r=0.61 and r=0.42). C0 (mean+/-SEM) levels were not significantly different in 34 patients with and 109 without AR (293+/-21 vs. 294+/-11 microg/L, P=0.95). AUC0-12 and AUC0-4 were significantly lower in patients with than without AR (AUC0-12 9090+/-598 vs. 10608+/-336 microg x h/L, P=0.01; AUC0-4 3934+/-306 vs. 4802+/-166 microg.h/L, P=0.006). In stepwise regression analysis only AUC0-12 or AUC0-4 (P=0.03/P=0.02) and delayed graft function (P=0.007) predicted AR. AUC0-12, AUC0-4, and C0 were all significantly higher in patients with CsANT than without CsANT (AUC0-12 11746+/-650 vs. 10023+/-301 microg x h/L, P=0.01; AUC0-4 5270+/-358 vs. 4474+/-150 microg x h/L, P=0.01; C0 343+/-18 vs. 287+/-10 microg/L, P=0.01), but in stepwise regression analysis C0 was not an independent predictor of CsANT. Patients with AUC0-12 in the range of 9500 to 11500 microg x h/L or AUC0-4 between 4400 and 5500 microg x h/L had the lowest incidence of AR (13% and 7%, respectively) without significantly higher risk for CsANT.

CONCLUSION

C0 correlates poorly with AUC based on PK0-4. Early AUC based on PK0-4 is more closely associated with AR and CsANT than is C0. Our data suggest that a target AUC0-12 of 9500-11500 or AUC0-4 of 4400-5500 microg x h/L may provide optimal Neoral immunosuppression.

The morbidity of prolonged wound drainage after kidney transplantation

PURPOSE

The consequences of prolonged wound drainage, defined as extravasation of more than 50 ml. fluid daily for more than 1 week through a drain or wound after renal transplantation, have not been well described in the literature. We examine the association of prolonged wound drainage with other clinical events, and its impact on hospitalization, and patient and graft survival.

MATERIALS AND METHODS

We prospectively documented prolonged wound drainage in 392 recipients of cadaver and live renal transplants from July 1993 to December 1997. Potential risk factors, associated outcomes within the first 6 months and effect on length of hospital stay due to prolonged wound drainage were determined.

RESULTS

Prolonged wound drainage was significantly associated with pre-transplantation weight, weight gain by post-transplantation day 3, delayed graft function and continuous ambulatory peritoneal dialysis on univariate analysis but only with delayed graft function (odds ratio 2.8, 95% confidence intervals 1.4 to 5.6) on multivariate analysis. Post-transplantation lymphoceles (5.2, 9 to 14), wound infection (27, 5.7 to 130) and wound dehiscence (5.8, 1.7 to 20) were associated with prolonged wound drainage. Patients with prolonged wound drainage stayed 8.7 additional days during the first hospitalization and overall 11.3 additional days during the first 6 months after transplantation independent of other co-morbid events, such as delayed graft function, rejection or cytomegalovirus disease.

CONCLUSIONS

Prolonged wound drainage is an important post-renal transplantation event that impacts patient outcomes and hospital resource use. Efforts to prevent this complication should be considered.

Safety and tolerability of cyclosporine and cyclosporine microemulsion during 18 months of follow-up in stable renal transplant recipients: a report of the Canadian Neoral Renal Study Group

BACKGROUND

There has been concern that the increased drug exposure associated with treatment with cyclosporine microemulsion (CsA-ME) would lead to an increase in adverse events.

METHODS

The long-term safety and tolerability of conventional cyclosporine (CsA) and CsA-ME were compared in a randomized, multicenter, pharmacoepidemiologic study involving 1097 stable renal transplant patients after 18 months of follow-up.

RESULTS

No significant difference was seen in change in serum creatinine or calculated creatinine clearance between the two groups. Episodes of deterioration in renal function (change in serum creatinine > or = 20%) were categorized with the following results for CsA-ME versus CsA, respectively: acute rejection, 4.5% vs. 4.5%; chronic rejection, 8% vs. 11%; CsA nephrotoxicity, 12% vs. 7% (P=0.008); transient changes, 17% vs. 12%; other causes, 4% vs. 6%. During the first 6 months of the study, a transient increase in the incidence of gastrointestinal and neurological adverse events was seen in the CsA-ME group compared with the CsA group. Up to 18 months, patients in the CsA group reported significantly fewer hearing and vestibular disorders, but more cardiovascular problems than those in the CsA-ME group (P=0.035).

CONCLUSIONS

Tolerance to CsA and CsA-ME was similar. Renal function over 18 months was not adversely affected by the increased drug exposure with CsA-ME, although there was a transient increase in nephrotoxicity. The frequency of acute and chronic rejection did not change.

A randomized, prospective multicenter pharmacoepidemiologic study of cyclosporine microemulsion in stable renal graft recipients. Report of the Canadian Neoral Renal Transplantation Study Group

BACKGROUND

The safety, tolerability, and pharmacokinetics of conventional cyclosporine (ConCsA) and cyclosporine microemulsion (MeCsA) were compared under conditions of normal clinical practice in a prospective, randomized, concentration-controlled, pharmacoepidemiologic study.

METHODS

Between September 1994 and March 1995, 1097 stable renal transplant recipients in 14 Canadian centers were randomized 2:1 to treatment with MeCsA or ConCsA. Patients were commenced on each study drug at a dose equal to their previous therapy with ConCsA, and the dose was adjusted to maintain predose whole blood cyclosporine concentrations within the therapeutic range established for each center. Prednisone and azathioprine were continued unless dose adjustment was required for clinical reasons.

RESULTS

The mean cyclosporine concentration was comparable in both treatment groups at all time points throughout the 6 months of follow-up. The mean dose of cyclosporine was 3.6 mg/kg/day in both treatment groups at entry to the study, and declined by 0.3% and by 2.8% in patients receiving ConCsA and MeCsA, respectively. The nature and severity of adverse events were similar in both treatment groups, but there was a transient increase in neurological and gastrointestinal complications in the group receiving MeCsA within the first month after conversion (P<0.05). Serum creatinine and creatinine clearance did not change in either treatment group throughout the study. Biopsy-proven acute rejection occurred in three patients (0.8%) receiving ConCsA and in seven patients (0.9%) receiving MeCsA, with non-histologically proven acute rejection in an additional three patients (0.8%) receiving ConCsA and five patients (0.6%) receiving MeCsA (P=NS). Serum creatinine rose transiently in 35 patients (9.8%) receiving ConCsA and 138 patients (18.7%) receiving MeCsA (P<0.05) and resolved either spontaneously or after a reduction in the cyclosporine dose. One graft was lost in the MeCsA group due to irreversible rejection, and seven patients died, three in the group receiving ConCsA and four of those receiving MeCsA (P=NS). Absorption of cyclosporine was more rapid and complete from MeCsA than from ConCsA during the first 4 hr of the dosing interval, resulting in almost 40% greater exposure to the drug (P<0.001). There was close correlation between area under the time-concentration curve (AUC) over the first 4 hr of the 12-hr dosage interval and AUC over the entire 12-hr dosage interval for both formulations, making AUC over the first 4 hr a good predictor of total cyclosporine exposure. Using this parameter, patients with low absorption randomized to receive MeCsA showed a marked increase in drug exposure by months 3 and 6, whereas there was no change in those who continued on ConCsA. A limited sampling strategy utilizing samples at the predose and postdose trough levels provided an excellent correlation with drug exposure, particularly for patients receiving MeCsA (r2=0.94 MeCsA vs. r2=0.89 ConCsA).

CONCLUSIONS

MeCsA appears to be a safe and effective therapy in stable renal transplant patients and provides superior and more consistent absorption of cyclosporine when compared with ConCsA. Transient toxicity after conversion to MeCsA occurs in some patients, and may reflect the increased exposure to cyclosporine. Use of a limited sampling approach combining trough and 2-hr postdose concentrations may provide an effective way to monitor this exposure.

Kidney transplantation, the Halifax experience

In the absence of a national kidney sharing system in Canada, virtually all the cadaver kidneys we transplant come from donors within the 4 provinces we serve. Currently the only criteria we use for recipient selection of cadaver kidneys, apart from ABO blood group matching and a negative anti-T-cell crossmatch, are good HLA match and transplant wait-list seniority. All transplant recipients receive CsA-based immunosuppression. Antibody induction is used only for repeat transplants and pediatric transplants. Recipients of first cadaver kidney transplants with zero HLA-DR mismatches have significantly better graft survival than those with mismatches. Graft and patient survival rates for first cadaver transplants continue to improve within the CsA era, and are comparable to those seen in centers routinely using antibody induction and routine sequential quadruple immunosuppression. Chronic graft nephropathy continues to be the most important cause of graft loss after the first year, unchanged over the past 2 decades, followed closely by death with a functioning kidney. The latter is a more important cause of loss in recipients older than age 60, and in recipients of HLA-identical live donor transplants. Repeat cadaver transplant recipients have a 5-year graft survival rate today equivalent to that seen with first cadaver transplants. Graft loss from acute rejection is modest, but kidneys requiring rescue therapy for steroid-resistant rejection have significantly poorer one- and 5-year graft survival and ultimately are lost from rejection. Patients with HLA-identical live-related donor transplants have better long-term survival with CsA than with azathioprine due to a decrease in graft loss from chronic rejection. Pre-transplant sensitization has an adverse effect on graft survival for haploidentical but not HLA identical live-related transplants. Patients over age 60 have equivalent graft survival to younger recipients for at least 7 years, and should not be precluded from receiving transplants by age alone. Prolonged CIT > 24 hours is associated with a significantly increased incidence and duration of ATN and need for dialysis, significantly increased early and late graft loss from acute and chronic rejection respectively, significantly reduced QALY's, and significantly higher early and late costs of transplantation.

Effect of calcium-channel blockers on cyclosporine clearance and use in renal transplant patients

OBJECTIVE

To determine the effect of calcium-channel blockers (CCBs) on cyclosporine dose, clearance, and cost, and their effect on kidney graft function and survival in patients who underwent kidney transplant.

DESIGN

A total of 176 adults receiving 177 transplants were studied retrospectively. Patients were stratified as follows: no CCB (n = 57), diltiazem (n = 13), nifedipine (n = 37), and verapamil (n = 70). Patients received cyclosporine 3-4 mg/kg by continuous infusion for 5 days followed by cyclosporine 10 mg/kg/d po to maintain initial whole blood concentrations of 300-400 ng/mL. Clearance of intravenously administered cyclosporine was calculated following at least 48 hours of the same dose by continuous infusion. The amount and cost of cyclosporine used during the first 10 days of oral therapy were also calculated.

RESULTS

Patients receiving diltiazem, but not verapamil or nifedipine, had decreased clearance of intravenously administered cyclosporine compared with that of the mean control group. The mean clearance of intravenously administered cyclosporine +/- SD in patients receiving no CCB was 5.1 +/- 1.5 mL/min/kg, diltiazem was 3.7 +/- 0.8 mL/min/kg, nifedipine was 6.4 +/- 1.9 mL/min/kg, and verapamil was 5.2 +/- 2.2 mL/min/kg. The amount and cost of 10 days of oral cyclosporine therapy was decreased in the verapamil group (5.7 +/- 1.5 g and $257 +/- 69) compared with that of the control group (6.7 +/- 1.6 g and $304 +/- 72) (p < 0.001). There was no significant difference among the groups with respect to immediate graft function, 1-year serum creatinine concentration, or 1-year graft survival.

CONCLUSIONS

Diltiazem decreased the clearance of intravenously administered cyclosporine. Although verapamil did not decrease the clearance of intravenously administered cyclosporine, it allowed a significant reduction in oral cyclosporine cost without apparent adverse effects on graft function. Further work is needed to determine the effect of CCBs on cyclosporine pharmacokinetics, especially with respect to their metabolism by gut and hepatic cytochrome P-450 enzymes, and their effect on patient outcome.

Prognostic factors in metastatic nonseminomatous germ cell tumours

OBJECTIVE

To determine predictors of prognostic significance for patients with nonseminomatous testicular cancer (NSTC) who have advanced disease at the time of presentation.

DESIGN

A chart review with a mean patient follow-up of 5.5 years (range from 0.75 to 13 years).

SETTING

University hospitals in Halifax.

PATIENTS

All patients with NSTC, stages II-B, II-C and III. Patients were excluded if the follow-up status at the time the study closed could not be determined. Thirty-three patients were included in the study. Current patient status was determined from the clinical charts and personal communication with the patients or their physicians.

INTERVENTIONS

All patients received cisplatinum-based chemotherapy. The extent of the disease was assessed by chest radiography or lung tomography, bone scanning, abdominal computed tomography or lymphangiography.

MAIN OUTCOME MEASURES

Correlation between levels of beta-human chorionic gonadotropin (BHCG) and alpha-fetoprotein (AFP), comparison of duration of symptoms before initial treatment, response to treatment and survival, and relationship between stage, tumour volume and survival.

RESULTS

The 3-year overall survival rate was 76%. Seven of 18 patients with symptoms for more than 16 weeks died of disease (p < 0.01). Overall complete response was seen in 27 of 33 patients. All initial nonresponders died. A survival rate of 93% was seen among initial complete responders (p < 0.01). All seven patients with persistent elevation of BHCG levels (p < 0.001) and the two patients with persistent elevation of AFP levels (p < 0.01) after the second course of chemotherapy died.

CONCLUSIONS

A symptomatic interval of more than 16 weeks, poor response to initial treatment, bulky retroperitoneal disease, larger volume lung disease and persistently elevated levels of BHCG and AFP were all indicators of poor prognosis.

Fate of renal allografts transplanted in patients with urinary diversion

Fifty-five kidneys were transplanted into 50 patients with supravesical urinary diversion at 16 transplant centers between 1970 and 1991. Of the 32 males and 18 females, 40 were adults (> or = 18 years) and 10 were less than 18 years old at the time of first transplant. Mean follow-up was 7.8 years. At last follow-up, 94% of recipients were alive and 73% of the kidneys were functioning. Fifteen kidneys were lost: 9 to rejection, 3 to noncompliance, and 3 patients died with a functioning kidney. Ten (18%) transplants were followed by surgical complications. Twenty-four (44%) were followed by medical complications of which urinary tract infection was most common. Recipients age 18 or younger had more urinary tract infections than older patients. No patient had urinary stones and no patient required medical treatment for metabolic abnormalities. We conclude that drainage of kidney transplants into a supravesical urinary diversion is an effective treatment for end-stage renal disease patients without adequate urinary bladders.

Early prediction of renal allograft loss beyond one year

Despite significant improvements in the results of renal transplantation since the introduction of cyclosporin, graft loss beyond the 1st year remains a significant and unresolved problem. In a retrospective analysis, 348 cyclosporin-treated renal transplant recipients with a functioning graft at 12 months were studied. Forty-eight patients in whom graft failure occurred in the 2nd and 3rd years were compared to 300 patients who maintained graft function beyond this time. Both groups were comparable with respect to donor and recipient features. Factors reflecting recipient immunological responsiveness--sensitization, previous transplantation and early rejection episodes--continued to affect graft survival beyond the 1st year. Surprisingly, there was a higher incidence of prior transfusion in the group with graft failure in the 2nd and 3rd years than in those with longer function (65% vs 24%). Serum creatinine levels at 3 and 6 months were also predictive of graft loss amongst patients with a functional graft at 1 year. It remains to be answered whether new immunosuppressive drugs and strategies will overcome these risks for late graft loss.

Reduction by combination prophylactic therapy with CMV hyperimmune globulin and acyclovir of the risk of primary CMV disease in renal transplant recipients

CMV-seronegative recipients of kidneys from CMV-seropositive donors (D+/R+) are at highest risk for developing clinical CMV disease. Even with routine prophylactic use of low-dose acyclovir we had a CMV disease incidence of 26% (5/19) in these patients. Published studies using either acyclovir or CMV hyperimmune globulin (HIG) alone as prophylaxis have also shown clinical disease in 20-30% of D+/R+ patients--less than controls but still significantly greater than in comparable CMV+ recipients (R+). The purpose of this study was to determine whether the risk of primary CMV disease in D+/R- patients was reduced by prophylaxis with combined CMV-HIG and low-dose acyclovir as follows: CMV-HIG (Immuno) 1 ml/kg i.v. immediately prior to transplantation and at 3-week intervals for 6 months; acyclovir 600 mg/day p.o. for 3 months. A total of 361 consecutive renal transplants were studied prospectively. All D+/R- pts (n = 73) received CMV-HIG and acyclovir, the others (91 D+/R+, 74 D-/R+, 123 D-/R-) received only low-dose acyclovir. The incidence of clinical CMV disease, CMV-related graft loss, graft and patient survival, and the influence of ALG and OKT-3 were analyzed and compared between groups. Of the 361 patients only 18 (5%) developed CMV disease, with 5 CMV-related graft losses. CMV disease occurred in only 10% of the D+/R- patients, lower than in previously reported studies. Significantly the incidence was as low as in CMV+ recipients of kidneys from both CMV+ (6%) and CMV- (7%) donors. Use of OKT-3 for steroid-resistant rejection increased the risk of developing CMV disease: 11/50 (22%) receiving OKT-3 developed CMV disease vs. only 7/311 (2%) who did not (P < 0.001); 11/18 (61%) with CMV disease had received OKT-3. ALG induction immunosuppression did not increase the risk of CMV in patients who subsequently received OKT-3. No patient developed CMV disease after discontinuing prophylaxis. There were no complications related to either CMV-HIG or acyclovir use. Compared with all other patients, the D+/R- group had superior graft survival at 1 and 3 years (94% vs. 87% and 86% vs. 74%, P < 0.05) but similar patient survival. Combined CMV-HIG and low-dose acyclovir appear to be better than either agent alone in preventing primary CMV disease in CMV- patients who receive CMV+ kidneys. Low-dose oral acyclovir (600 mg/day) may be as effective in preventing CMV disease as higher-dose prophylactic regimens, at least when accompanied by CMV-HIG.(ABSTRACT TRUNCATED AT 400 WORDS)