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Cyclosporine A (CSA) and tacrolimus (FK506) are powerful immunosuppressive agents that have proven useful for antirejection therapy in patients with solid organ transplants, including kidney. However, both drugs are nephrotoxic, each producing similar histological patterns of injury to renal tubules and preglomerular arterioles, and this toxicity is a major cause of renal allograft dysfunction. A renal transplant biopsy presently represents the most reliable means of diagnosing nephrotoxicity caused by CSA or tacrolimus and distinguishing it from acute rejection. Because CSA and tacrolimus nephrotoxicity often involve arteriolar smooth muscle, whereas vascular smooth muscle is rarely involved in acute rejection, we investigated if the appearance of a smooth muscle-specific isoform of alpha-actin (SMA) in the urine of renal transplant recipients about to undergo a biopsy for graft dysfunction correlated with biopsy evidence of CSA or tacrolimus toxicity. Eighty-nine urine samples from 61 patients, plus 6 samples from healthy control subjects, were analyzed in a blinded manner by enzyme-linked immunosorbent assay using a specific anti-SMA monoclonal antibody. For the patient samples, the results of these assays were then correlated with the biopsy findings. Those 40 cases in which the biopsy showed evidence of CSA or tacrolimus nephrotoxicity had a significantly (P < 0.01) greater SMA level in the corresponding urine samples (0.089 +/- 0.126 microgram/mL; mean +/- SD) than the 49 cases without toxicity (0.018 +/- 0.027 microgram/mL) or 6 control subjects (0.003 +/- 0.007 microgram/mL), although there was considerable overlap of SMA values among these groups. The greatest SMA levels were seen in patients with CSA or tacrolimus nephrotoxicity that was likely to be relatively acute, namely those with thrombotic microangiopathy and those without previous biopsy evidence of toxicity. SMA levels correlated significantly with the estimated severity of arteriolopathy on biopsy. In patients with tubular but not arteriolar lesions of CSA or tacrolimus toxicity, the mean SMA level was not significantly greater than that in patients without toxicity. Urine SMA levels in patients with a biopsy specimen showing acute rejection were not significantly different from those in patients without rejection, and there was no correlation between urine SMA level and severity of rejection. Whereas the degree of overlap of SMA levels in patients with and without nephrotoxicity was far too great to consider this assay as a potential alternative to renal transplant biopsy for the diagnosis of nephrotoxicity, the assay may have potential as a marker for active arteriolar injury in renal transplant recipients and other patients receiving CSA or tacrolimus therapy.

Although FK 506 has been shown to effectively reverse refractory renal allograft rejection, its ability to reverse accelerated renal allograft rejection as a primary agent has not been specifically addressed. Herein evidence of the ability of FK 506 to reverse accelerated renal allograft rejection is presented. A 16-yr-old highly sensitized (PRA 75%) male underwent a second cadaveric renal transplant procedure. Despite induction immunosuppression with ATGAM, cyclosporine, azathioprine, and corticosteroids, a marked elevation in serum creatinine (1.6-->2.1 ng/dl) and reduction in urine output (4000 ml/d-->1000 ml/d) were observed on the sixth post-transplant day. Renal allograft biopsy performed at that time revealed typical features of accelerated rejection including neutrophil margination in glomerular and interstitial capillaries, and C3, IgG, and fibrin deposition in glomerular and interstitial capillaries (by immunofluorescence). FK 506 therapy was promptly instituted and ATGAM therapy discontinued. Serum creatinine peaked within 3 d of FK 506 therapy (2.5 mg/dl) and subsequently progressively dropped to 1.2 mg/dl. Repeat biopsy on FK 506 treatment day 12 revealed marked histologic improvement. Renal function remains excellent (1.3 mg/dl) 18 months after initiation of FK 506 therapy, and recurrent rejection has not been observed. This experience provides evidence that FK 506 therapy may effectively reverse accelerated renal allograft rejection, and that it provides a means for treating antibody-mediated mechanisms of allograft rejection.

Background: A study was performed by 17 different U.S. liver transplantation centers to determine the safety and efficacy of conversion from cyclosporine to tacrolimus for chronic allograft rejection., Methods: Ninety-one patients were converted to tacrolimus a mean of 319 days after liver transplantation. The indication for conversion was ongoing chronic rejection confirmed by biochemical and histologic criteria. Patients were followed for a mean of 251 days until the end of the study., Results: Sixty-four patients (70.3%) were alive with their initial hepatic allograft at the conclusion of the study period and were defined as the responder group. Twenty-seven patients (29.7%) failed to respond to treatment, and 20 of them required a second liver graft. The actuarial graft survival for the total patient group was 69.9% and 48.5% at 1 and 2 years, respectively. The actuarial patient survival at 1 and 2 years was 84.4% and 81.2%, respectively. Two significant positive prognostic factors were identified. Patients with a total bilirubin of < or = 10 mg/dl at the time of conversion had a significantly better graft and patient survival than patients converted with a total bilirubin > 10 mg/dl (P=0.00002 and P=0.00125, respectively). The time between liver transplantation and conversion also affected graft and patient survival. Patients converted to tacrolimus < or = 90 days after transplantation had a 1-year actuarial graft and patient survival of 51.9% and 65.9%, respectively, compared with 73.2% and 87.7% for those converted > 90 days after transplantation. The mean total bilirubin level for the responder group was 7.1 mg/dl at the time of conversion and decreased significantly to a mean of 3.4 mg/dl at the end of the study (P=0.0018). Thirteen patients (14.3%) died during the study. Sepsis was the major contributing cause of death in most of these patients., Conclusions: Our results suggest that conversion to tacrolimus for chronic rejection after orthotopic liver transplantation represents an effective therapeutic option. Conversion to tacrolimus before development of elevated total bilirubin levels showed a significant impact on long-term outcome.

Unlabelled: Protocol biopsies were performed to define the histologic response to tacrolimus therapy in patients with refractory acute renal allograft rejection. Renal allograft biopsies were performed at defined intervals after initiation of tacrolimus therapy. Protocol biopsies were performed before tacrolimus therapy (within 48 hr of initiation of therapy) and after 1 week of therapy. If the 1-week biopsy did not show rejection reversal, repeat protocol biopsies were obtained at 1- to 2-week intervals, until histologic reversal was observed. Additional biopsies were obtained at 4 weeks and at 8-12 weeks after initiation of tacrolimus therapy. Indicated biopsies were also performed to evaluate increases in serum creatinine. A total of 92 biopsies were performed in 23 patients (average 4.0 biopsies/ patient). Biopsies were performed in each patient immediately before starting tacrolimus therapy (23 biopsies), and 69 biopsies (3.0 biopsies/patient) were performed during tacrolimus therapy. Rejection diagnosis was based on strict Banff criteria. Pretacrolimus biopsies demonstrated mild acute rejection in 64% of patients and moderate acute rejection in 36%. One week after initiation of tacrolimus therapy, protocol biopsies revealed the following: no rejection (60%), improvement (13%), no change (20%), and worsening rejection (7%). Histologic changes at 1 week did not correlate with changes in renal function, as 63% of patients that showed histologic improvement or reversal during the first 2 weeks of therapy did not show improvement in serum creatinine. A lack of histologic improvement (or worsening) at 1 week was demonstrated in a significant proportion of patients (27%); increased tacrolimus dosing provided rejection reversal or improvement in 1-2 weeks in each of these patients. Recurrent rejection was diagnosed on eight biopsies in seven patients, however six episodes were diagnosed by protocol biopsies alone (i.e., in the absence of an elevation in serum creatinine). Delayed improvement in renal function, despite histologic reversal, was likely due to physiologic effects of tacrolimus (i.e., afferent arteriolar vasoconstriction), as histologic evidence of tacrolimus toxicity was not observed during the first 2 weeks of therapy. Histologic evidence of tacrolimus nephrotoxicity (nodular arteriolar hyalinosis) was found in 21% (15 of 69) of biopsies in 39% of patients (9 of 23) at a median time of 60 days (range 12-150 days). Tacrolimus dose and blood levels (by IMx assay) did not correlate with development of clinically silent or clinically evident nephrotoxicity., In Conclusion: 1) protocol biopsies provide information that allows individualization of tacrolimus rejection therapy, 2) histologic resolution of rejection often precedes biochemical improvement, 3) histologic evidence of tacrolimus nephrotoxicity is seldom observed in the first 2 weeks of therapy, and 4) clinically silent recurrent rejection and clinically silent tacrolimus nephrotoxicity are observed with significant frequency during tacrolimus therapy for refractory renal allograft rejection.

A multicenter trial was conducted to evaluate the efficacy and safety of tacrolimus in the treatment of refractory renal allograft rejection. Renal transplant recipients experiencing biopsy-proven recurrent acute allograft rejection were eligible if the current rejection episode was refractory to corticosteroids. A total of 73 patients were enrolled, of whom 59 (81%) had previously received at least one course of antilymphocyte antibody as rejection therapy. One-year follow-up was available in 93% of patients. Median time to tacrolimus rescue therapy was 75 days after transplantation (range, 18-1448 days). Therapeutic responses to tacrolimus included improvement in 78% of patients, stabilization in 11%, and progressive deterioration in 11%. The risk of experiencing progressive deterioration was related to the pretacrolimus serum creatinine level: serum creatinine < or = mg/dl, 3%; 3.1-5 mg/dl, 16% (P < 0.04); > 5 mg/dl, 23% (P < 0.02). Twelve-month (from the time of initiation of tacrolimus therapy) actuarial patient and graft survival rates were 93% and 75%. Graft loss occurred in 19 patients (25%) at a median time of 108 days. Fourteen episodes of recurrent rejection were diagnosed in 10 patients (14%), at a median time of 101 days. Eleven episodes of recurrent rejection were treated (three patients underwent transplant nephrectomy), with resolution achieved in nine patients. Antilymphocyte antibody therapy was not used to treat recurrent rejection. Serum creatinine values improved during tacrolimus therapy: median serum creatinine level before tacrolimus, 3.2 mg/dl; median at 1 year after tacrolimus, 1.8 mg/dl. Twelve infections were documented in 11 patients (15%), including cytomegalovirus infection in three patients (4%). Posttransplant lymphoproliferative disorder was diagnosed in a single patient. Tacrolimus whole blood levels averaged 15.0 +/- 9.9 ng/ml at day 7 of tacrolimus therapy and 9.4 +/- 5.1 ng/ml at 1 year, and were consistent among individual centers. Treatment outcome did not correlate with tacrolimus blood levels. The most commonly observed adverse events were neurological and gastrointestinal. Seventy-four percent of patients received tacrolimus for at least 1 year. Tacrolimus therapy was discontinued in 18% of patients for rejection (11% for progressive, unrelenting rejection, and 7% for recurrent rejection). Tacrolimus therapy was discontinued in 8% of patients due to adverse events. In conclusion, tacrolimus rescue therapy provides (1) prompt, effective reversal of refractory renal allograft rejection, (2) good long-term renal allograft function, (3) a low incidence of recurrent rejection, and (4) an acceptable safety profile in renal allograft recipients experiencing refractory rejection.

FK 506 has proven to be an effective immunosuppressive agent in liver transplantation, but its role in renal transplantation remains to be defined. Since the initial availability of FK 506 for treatment of refractory renal allograft rejection, we have applied an aggressive approach consisting of institution of rescue therapy at an early point in the rejection process combined with assiduous monitoring of FK 506 blood levels and the histologic response to therapy. A total of 17 adult patients were treated for refractory renal allograft rejection with this approach. Median follow-up was 9 months post-initiation of FK 506 therapy. Median time to first rejection was 26 d post-transplant, and median time to FK 506 rescue therapy was 113 d post-transplant. Sixteen of 17 patients received either ATGAM or OKT3 induction therapy. Prior to FK 506 rescue therapy, patients received the following antirejection therapy: corticosteroids 40 + 21 mg/kg (prednisone or Solumedrol), OKT3 (median 14 d), ATGAM (3 patients, 14 d each). FK 506 rescue therapy was successful in reversing the rejection process in all 17 patients. Fifteen patients (88%) demonstrated rapid reversal of rejection (i.e. reversal within 14 d), whereas three patients demonstrated delayed reversal. Nine month actuarial patient and graft survivals were 92% and 84%. When censored for documented noncompliance, nine month actuarial graft survival was 92%. Good long-term renal function was observed (pre-FK 506 baseline creatinine 2.1 +/- 0.5 mg/dl, current serum creatinine 2.1 +/- 0.6 mg/dl. Six recurrent rejection episodes occurred in 5 patients (29%) with a median time to recurrent rejection of 59 d post-initiation of FK 506 rescue therapy. Each recurrent rejection episode was successfully treated by corticosteroids and/or increased FK 506 dose. CMV disease and lymphoma were not observed. Histologic evidence of FK 506 nephrotoxicity (hyaline necrosis in preglomerular arterioles) was observed in 6 patients 30% (median time to diagnosis 49 d). FK 506 blood levels (whole blood TDX) between 10 and 20 ng/ml provided effective reversal in most patients. Current FK 506 dose and blood levels are 0.18 +/- 0.09 mg/kg/d and 7 +/- 2 ng/dl). FK 506 rescue therapy also allowed aggressive reductions in prednisone dose: (mean current prednisone dose 0.08 +/- 0.05 mg/kg/d). In conclusion, an aggressive approach toward FK 506 rescue: 1) provides prompt, effective reversal of refractory renal allograft rejection, 2) good long-term renal allograft function, 3) balanced immunosuppression with respect to recurrent rejection, opportunistic infection and PTLD, 4) acceptable toxicity, and 5) aggressive reduction in corticosteroid dosing. Based on these findings, FK 506 rescue therapy is now the treatment of choice in our program for renal allograft rejection episodes that occur following antilymphocyte antibody therapy.

Twelve patients who experienced steroid-resistant rejection after primary liver transplantation while receiving cyclosporine-based therapy were converted to tacrolimus without receiving OKT3 or additional steroids. The indications for conversion were ongoing biopsy-confirmed rejection. All patients had received one course of high-dose intravenous steroids, which failed to reverse the rejection episode. No other antirejection therapy was given. Tacrolimus was initiated to reverse rejection and for maintenance therapy. The tacrolimus target level was 15-20 ng/ml (whole blood, IMX). All 12 patients had rapid reversal of the rejection episode and did not experience recurrent rejection (mean follow-up: 8.2 +/- 1.2 months). The mean bilirubin level dropped from 6.1 mg/dl at the initiation of tacrolimus therapy to 4.4 mg/dl by day 7 of therapy, 2.5 mg/dl by day 14, and 1.5 mg/dl by day 21 (P < 0.003). Serum glutamic pyruvic transaminase demonstrated a similar response. The serum creatinine level was unchanged at 1.5 mg/dl. No major adverse reactions were noted in this group of patients. Patient and graft survival rates were 100%. Four of the eight patients with a follow-up of >4 months are no longer receiving steroid therapy. Tacrolimus is effective as the primary therapy for the treatment of steroid-resistant rejection and provides a rapid and sustained biochemical response. Patients with mild to moderate rejection may be safely converted from cyclosporine to tacrolimus without an additional steroid bolus or OKT3 therapy. Early "preemptive" conversion to tacrolimus prior to the use of additional steroids or OKT3 may decrease overall rejection therapy requirements. This approach has promise for improved graft survival and fewer infectious and immunologic complications.