Minimal Immunosuppression Research Articles

Minimization of immunosuppression in adult liver transplantation: new strategies and tools

To describe most relevant data regarding strategies to achieve immunosuppression minimization and/or complete withdrawal in liver transplantation and to discuss the development of tolerance biomarkers to predict the success of immunosuppression weaning. In clinical organ transplantation allograft tolerance has been attained through two different pathways: (1) tolerance or immunosuppression minimization has been attempted by administering induction therapies with or without infusion of donor hematopoietic cells; and (2) the availability of spontaneously tolerant liver and kidney recipients has been exploited to develop biomarkers of allograft tolerance. The use of transcriptional profiling is the most promising approach. Recent publications have identified a gene expression signature in tolerant patients. Current immunosuppressive regimens reduce acute rejection episodes but promote a number of complications that have a negative impact on patient morbidity, mortality and quality of life. In this setting, achievement of tolerance is a major goal. Although there are no reliable markers to identify tolerant patients, recent studies have found that tolerant liver recipients exhibit unique peripheral blood transcriptional patterns. The difference in expression patterns is related to the immune response and could constitute the basis of a future diagnostic test of tolerance.

Cell therapy approaches aiming at minimization of immunosuppression in solid organ transplantation

Cell transplantation or administration of cellular products has escaped preclinical experimental status and will be integrated as a substantial component of future individualized treatment modalities for a broad scope of medical fields, including transplantation tolerance, cancer immunotherapies and auto-immune diseases. Renal allograft tolerance has been successfully demonstrated using bone marrow transplantation with nonmyeloablative conditioning to induce transient hematopoietic chimerism, hereby exemplifying the immunomodulatory potential of living cells to reprogram an existing immune system to recognize and accept nonself major histocompatibility antigens expressed on the allogeneic donor organ. Strong efforts are currently undertaken to circumvent the necessity of hematopoietic chimerism induction by harnessing peripheral regulatory mechanisms. Potential candidate cell populations that bear immunomodulating and regulatory properties comprise regulatory T cells, dendritic cells and deactivated macrophages as well as stem cells of various origins, currently tested in different clinical transplantation tolerance trials. Although transplantation tolerance is still on its way to be reliably accomplished in clinical settings, use of well specified and functionally characterized cellular therapeutics with regulatory properties is now entering the field of personalized medicine for transplanted patients to benefit from minimization protocols and less severe side affects related to conventional immunosuppressive drug treatment.

Effect of Denileukin Diftitox on Pruritus and Other Skin-Related Symptoms Vs Placebo In Patients with Cutaneous T-Cell Lymphoma

AbstractAbstract 4922 Introduction.Cutaneous T-cell lymphoma (CTCL) is a heterogeneous group of non-Hodgkin's lymphomas (NHLs) that develop primarily in the skin but may progress to involve lymph nodes, blood, and visceral organs. CTCL is characterized by skin patches, plaques, tumors, and erythroderma. Pruritus is frequently associated with skin lesions in CTCL and may be severe. Some treatments have been noted to produce improvements in pruritus that appears to be independent of the response rate. Denileukin diftitox (DD, Ontak), a recombinant fusion protein targeting IL-2-receptor-expressing T lymphocytes, has demonstrated a significant effect on overall response rate with minimal immunosuppression in patients with CD25 assay-positive CTCL. For this post-hoc analysis, we used data from a randomized, double-blind, placebo-controlled, phase III clinical trial to assess the effect of DD on pruritus and overall skin condition in patients with CTCL. Patients and methods.Patients with CD25 assay-positive, stage Ia to III CTCL were randomized to receive 9 μg/kg/d DD (n=45), 18 μg/kg/d DD (n=55), or placebo (n=45). Study medications were administered on the first 5 days of a 21-day cycle for up to 8 cycles. Four grading scales were used to assess clinical signs and symptoms (Table 1). Results.Higher percentages of DD-treated patients experienced clinically significant improvements in skin-related symptoms than did patients on placebo during treatment and follow-up (Table 2). The differences between the proportions of patients in the placebo group experiencing clinically significant improvement and the proportions of those in the 18 μg/kg/d and combined DD dose groups were statistically significant for all 4 assessments. Substantially more DD-treated patients had ≥20% and ≥50% improvement in pruritus (relative to baseline) at any time than those receiving placebo; improvements were maintained for ≥6 weeks. The global skin score improvement and pruritus score improvement in both high dose and low dose groups were significantly correlated, with higher correlation in high dose group compared to low dose group (p=0.0004 vs p=0.0381). There is no correlation in placebo group for the two scores (p=0.3798). Improvement in pruritis was to some extent independent of response, as demonstrated by the proportion of agreement between tumor response and significant pruritus improvement (27% and 19% for high dose and low dose, respectively, in DD groups), based on Kappa concordance coefficient. Conclusion.Patients treated with DD, particularly at the 18-μg/kg/d dose, were more likely to experience clinically significant improvements in pruritus and other skin-related symptoms than were patients receiving placebo. DD was observed to improve pruritus independent of response. Disclosures:Kozlovski: Eisai Inc.: Employment.

4-Log Ex-Vivo T-Lymphocyte Depleted Myeloablative HLA-Matched Sibling Transplants; a Platform for Adoptive Immunotherapy

AbstractAbstract 2091▪Allogeneic hematopoietic stem cell transplantation (HSCT) strategies must serve as platforms for adoptive cellular immunotherapy if the graft-versus-leukemia (GVL) effect is to be fully exploited. In sequential clinical trials at the National Institutes of Health we have used ex-vivo T cell depletion to develop an HSCT with minimal graft versus host disease (GvHD) prophylaxis followed by elective donor lymphocyte infusion on day 90. T-cell depletion creates the lymphodepleted environment for preferential homeostatic expansion of adoptively infused cells, while minimization of post-transplant immunosuppression promotes expansion of the adoptively transfused cells. Since non-engraftment is a limiting complication with extreme T lymphocyte depletion and reduced GvHD prophylaxis, we measured lineage-specific chimerism and clinical outcomes utilizing our optimized approach. Thirty-six patients with hematologic malignancies underwent allogeneic HSCT with a graft from their HLA-identical siblings. The median age was 43 years (range 16–68), 50% were males. Transplant indications were AML(17), ALL (7), MDS (6), CML (2), CLL (2), NHL (1) and CMMoL (1). 50% were standard risk and 50% were high risk. Subjects received myeloablative conditioning regimen with cyclophosphamide (60 mg/kg/dose × 2), fludarabine (25 mg/m2/dose × 5) and total body irradiation (12 Gy divided in 8 fractions, with lung shielding to 6 Gy). Subjects 55 years of age and older received 4 Gy divided in 8 fractions without lung shielding. G-CSF mobilized peripheral blood stem cells from the donor were CD34+ selected by the Miltenyi CliniMacs system, with infusion of a target CD34+ dose of 6 × 106/kg (range 3 to 10 × 106/kg) and a fixed CD3+ dose of 5 × 104/kg. Low-dose cyclosporine till day 21 was the sole GVHD prophylaxis. Delayed lymphocyte add back (5 × 106 CD3+/kg) was given at day 90 in the absence of significant GvHD. CD3+ and myeloid chimerism analysis were performed sequentially on peripheral blood with early lymphocyte add back in cases with falling chimerism. Day 200 overall survival (the primary study endpoint) was 84%. One patient, who was postpartum, failed to engraft and required a second transplant. 34/36 subjects achieved complete donor (>95%) myeloid chimerism by day 14 and the median time to complete donor CD3+ chimerism was 45 days. The incidence of acute GVHD grade II, III and IV were 23%, 2.9% and 0%, respectively. The incidence of chronic GVHD was 34.3%. At a median follow up of 3.7 years, Kaplan-Meier estimates of relapse, nonrelapse mortality and overall survival were 32%, 31% and 46% respectively. In conclusion, transplants utilizing this approach have acceptable engraftment and clinical outcomes and may serve as an ideal platform for adoptive cellular immunotherapy. [Display omitted] Disclosures:No relevant conflicts of interest to declare.

Cost-Effective Immunosuppressive Options for Solid Organ Transplantation: A Guide to Lower Cost for the Renal Transplant Recipient in the USA

Of the numerous risks associated with immunotherapy for the prevention of rejection, cost is perhaps the most universal. In the USA and some other countries, the costs of immunosuppression make transplantation unavailable for some medically viable transplant candidates, and for others who receive a transplant, the long-term costs are economically crippling. Minimization and tapering of immunosuppression, use of generics, manipulation of metabolism, infection surveillance instead of prophylaxis, and advantageous routes of administration are some strategies that can be employed to reduce immunotherapy expense. Using these strategies, we describe an immunosuppression regimen for kidney transplantation that might be only a third of the cost of current 'standard' regimens in the USA. Such a regimen might allow some patients who might not otherwise qualify economically to safely receive a kidney transplant. The purpose of creating an alternative, lower-cost immunotherapy regimen is to give patients a choice. Responsible stewardship of scarce donor organs is the primary, and clearly appropriate, limiting factor.

Alemtuzumab in Solid Organ Transplantation and in Composite Tissue Allotransplantation

Alemtuzumab (Campath®, Genzyme Corporation, MA, USA) is a potent monoclonal antilymphocyte, anti-CD52 antibody. Since the 1980s, alemtuzumab has been used extensively in organ transplantation as an induction agent - also with the aim of avoiding or reducing maintenance immunosuppression. We herein review the literature on alemtuzumab in solid organ and composite tissue allotransplantation with an emphasis on clinical and mechanistic aspects of alemtuzumab. In summary, the use of alemtuzumab in solid organ and composite tissue allotransplantation shows excellent early results and holds potential for wider use in conjunction with immunosuppression minimization protocols.

Infusion of Lin − bone marrow cells results in multilineage macrochimerism and skin allograft tolerance in minimally conditioned recipient mice

Donor-specific immunological tolerance using high doses of donor bone marrow cells (BMC) has been demonstrated in mixed chimerism-based tolerance induction protocols; however, the development of graft versus host disease (GVHD) remains a risk. In the present study, we demonstrate that the infusion of low numbers of donor Lin − bone marrow cells (Lin − BMC) 7 days post allograft transplantation facilitates high level macrochimerism induction and graft tolerance. Full-thickness BALB/c skin allografts were transplanted onto C57BL/6 mice. Mice were treated with anti-CD4 and anti-CD8 mAbs on day 0, + 2, +5, +7 and +14 along with low dose busulfan on day + 5. A low dose of highly purified Lin − BMC from BALB/c donor mice was infused on day + 7. Chimerism and clonal cell deletion were evaluated using flow cytometry. Donor-specific tolerance was tested by donor and third-party skin grafting and mixed leukocyte reaction (MLR). Lin − BMC infusion with minimal immunosuppression led to stable, mixed, multilineage macrochimerism and long-term allograft survival (> 300 days). Mixed donor-recipient macrochimerism was observed. Donor-reactive T cells were clonally deleted and a 130% increase in CD4 +CD25 +Foxp3 + regulatory T cells (Tregs) was observed in the spleen. Tolerant mice subsequently accepted second donor, but not third-party (C3H), skin grafts and recipient splenocytes failed to react with allogeneic donor cells indicating donor-specific immunological tolerance was achieved. We conclude that the infusion of donor Lin − BMC without cytoreductive recipient conditioning can induce indefinite survival of skin allografts via mechanisms involving the establishment of a multilineage macrochimeric state principally through clonal deletion of alloreactive T cells and peripherally induced CD4 +Foxp3 + Tregs.

Biomarkers of immunoregulatory status in stable liver transplant recipients undergoing weaning of immunosuppressive therapy

Biomarkers that reflect immune response recovery and predict clinical events during withdrawal or minimization of immunosuppressive therapy have not been evaluated. This study aimed to evaluate whether immune response recovers after withdrawal of long-term immunosuppressive treatment in stable liver transplant patients and to determine whether specific biomarkers reflect immune response reactivity and predict rejection. Pharmacokinetic–pharmacodynamic profiles were determined in 24 patients and 80 healthy donors before immunosuppressive treatment reduction began, at 50%, and at complete withdrawal. In patients who rejected, effector-T-cell response mediated by soluble IFN-γ, %CD4 +IFN-γ and %CD8 +IL-2/IFN-γ were significantly increased, while TGF-β1 production and the TGF-β1/IFN-γ ratio were significantly decreased. In patients with rejection, soluble IFN-γ and %CD8 +IL-2 were significantly higher before immunosuppressive treatment was reduced. Further studies are required, but this battery of biomarkers performed in whole blood could be a useful tool to monitor immunosuppressive treatment minimization or withdrawal protocols and identify patients at increased risk of rejection.

Toward a B-cell signature of tolerance?

Operational tolerance is a rare and still unexplained phenomenon in organ transplantation. Pallier et al. analyzed the peripheral B-cell compartment of 12 renal transplant patients with drug-free long-term graft function and found a peculiar blood B-cell phenotype, with an expansion of memory activated B cells and increased expression of inhibitory molecules, suggesting a role of B cells in maintaining graft tolerance.

Preemptive Retransplant for BK Virus Nephropathy Without Concurrent Transplant Nephrectomy

Preemptive Retransplant for BK Virus Nephropathy Without Concurrent Transplant Nephrectomy

Identification of a B cell signature associated with renal transplant tolerance in humans

Establishing long-term allograft acceptance without the requirement for continuous immunosuppression, a condition known as allograft tolerance, is a highly desirable therapeutic goal in solid organ transplantation. Determining which recipients would benefit from withdrawal or minimization of immunosuppression would be greatly facilitated by biomarkers predictive of tolerance. In this study, we identified the largest reported cohort to our knowledge of tolerant renal transplant recipients, as defined by stable graft function and receiving no immunosuppression for more than 1 year, and compared their gene expression profiles and peripheral blood lymphocyte subsets with those of subjects with stable graft function who are receiving immunosuppressive drugs as well as healthy controls. In addition to being associated with clinical and phenotypic parameters, renal allograft tolerance was strongly associated with a B cell signature using several assays. Tolerant subjects showed increased expression of multiple B cell differentiation genes, and a set of just 3 of these genes distinguished tolerant from nontolerant recipients in a unique test set of samples. This B cell signature was associated with upregulation of CD20 mRNA in urine sediment cells and elevated numbers of peripheral blood naive and transitional B cells in tolerant participants compared with those receiving immunosuppression. These results point to a critical role for B cells in regulating alloimmunity and provide a candidate set of genes for wider-scale screening of renal transplant recipients.

Immune “tolerance profiles” in donor bone marrow infused kidney transplant patients using multiple ex vivo functional assays

Ex vivo identification of donor-specific unresponsiveness in organ transplant recipients is important for immunosuppression (IS) minimization. We tested three groups of stable living, related-donor kidney transplant patients up to 11 years postoperatively, i.e., 20 haploidenticals with donor bone marrow cell (DBMC) infusions, eight noninfused haploidentical controls (haplo controls), and 11 HLA-identical controls (HLA-id), using multiple ex vivo immune assays. We observed that no patients developed donor-specific antibodies. The majority showed donor-specific CTL unresponsiveness from year 1 onward. Thirteen of 20 DBMC recipients became specifically donor MLR nonreactive. Depletion of donor cells in DBMC recipients still MLR reactive increased donor-specific reactivity by 75% ± 36% ( p = 0.04). Adding them back in low concentration caused antigen specific inhibition. The frequencies of ELISPOT granzyme-B and interferon-γ–producing cells somewhat paralleled the CTL and MLR responses. In the trans vivo DTH, 14 of 19 DBMC recipients demonstrated donor-specific unresponsiveness and 16 of 19 showed “linked suppression,” vs none of eight and one of eight haplo controls and vs six of 10 and one of 10 HLA-ids, respectively. Most importantly, when all six assays were performed simultaneously, 10 of 18 DBMC, five of 10 HLA-ids, and no haplo controls were specifically donor unresponsive long term. We propose that a cluster analysis combining these assays will reveal tolerant recipients in whom IS minimization may safely be tested. This appears to have occurred in many DBMC-infused recipients.

Long-term monitoring of Epstein-Barr virus DNA load and humoral parameter abnormalities in pediatric liver transplant recipients before development of malignancy

EBV loads and abnormalities of humoral responses were monitored in 51 pediatric liver transplant recipients as a proposed non-invasive laboratory tool for early detection of changes preceding severe clinical complications. EBV DNA load, concentrations of IgM, IgG, IgA, and monoclonal proteins were determined in each blood sample. EBV DNA was detected in 70.6% of the children, dysgammaglobulinemia of one or more Ig isotype was present in 41.2% of them. MG detected in 43.1% of patients correlated with the presence of EBV DNA (p = 0.003) and was usually preceded by hypergammaglobulinemia. The median maximum EBV load was significantly higher in EBV DNA+/MG+ patients than in EBV DNA+/MG- patients (p = 0.04), although there was no correlation between current viral load and appearance of MG. Four of 15 EBV DNA-negative patients developed MG, preceded by hypergammaglobulinemia in two. Minimization or cessation of immunosuppression in 42 patients, in whom abnormal biomarkers and/or clinical symptoms raised suspicion of disease progression, permitted complete resolution of abnormalities in all but one patient who developed B-NHL and died. Simultaneous monitoring of protein profiles and EBV DNA load together with thorough physical evaluation of children after LTx is important for early implementation of suitable preemptive therapy.

Cryptogenic organizing pneumonia after rituximab therapy for presumed post-kidney transplant lymphoproliferative disease

Cryptogenic organizing pneumonia (COP, formerly bronchiolitis obliterans organizing pneumonia) is rare in children. We describe an 11-year-old girl with Epstein-Barr virus (EBV) reactivation/presumed post-transplant lymphoproliferative disease (PTLD) 15 months after undergoing a deceased donor kidney transplantation. Treatment with reduced immunosuppression, ganciclovir, and cytomegalovirus immunoglobulin was complicated by severe graft rejection, prompting therapy with methylprednisolone, anti-thymocyte globulin and four weekly doses of rituximab (total 1500 mg/m(2)). Tacrolimus- and prednisone-based anti-rejection prophylaxis was complemented with low-dose sirolimus. When the lactate dehydrogenase and uric acid levels rose 10 weeks after the first rituximab infusion and bilateral pulmonary nodules were detected by computerized tomography, recurrence of PTLD was suspected. Open lung biopsy of the clinically asymptomatic patient identified the nodules as COP, characterized by abundant CD3(+) T-cells, few B-cells, and the absence of EBV, cytomegalovirus, or adenovirus antigens. With normalization of the peripheral B-cell count, EB viremia reappeared and persisted, despite minimal immunosuppression. Four years later, the patient was diagnosed with classical Hodgkin lymphoma-type PTLD with multiple pulmonary and abdominal nodes. This first report of rituximab-associated, pediatric COP highlights the risk of pulmonary complications after treatment with B-cell depleting agents in solid organ transplant recipients, and the importance of a histopathologic diagnosis and vigilant follow-up of such lesions.

BK-Virus and the Impact of Pre-Emptive Immunosuppression Reduction: 5-Year Results

A 1-year, single-center, randomized trial demonstrated that the calcineurin inhibitor or adjuvant immunosuppression, independently, does not affect BK-viruria or viremia and that monitoring and pre-emptive withdrawal of immunosuppression was associated with resolution of BK-viremia and absence of clinical BK-nephropathy without acute rejection or graft loss. A retrospective 5-year review of this trial was conducted. In cases of BK viremia, the antimetabolite was withdrawn and for sustained viremia, the calcineurin inhibitor was minimized. Five-year follow-up was available on 97% of patients. Overall 5-year patient survival was 91% and graft survival was 84%. There were no differences in patient-survival by immunosuppressive regimen or presence of BK-viremia. Immunosuppression and viremia did not influence graft survival. Acute rejection occurred in 12% by 5-years after transplant, was less common with tacrolimus versus cyclosporine (9% vs. 18%; p = 0.082), and was lowest with the tacrolimus-azathioprine regimen (5%, p = 0.127). Tacrolimus was associated with better renal function at 5-years (eGFR 63 FK vs. 52 CsA mL/min, p = 0.001). Minimization of immunosuppression upon detection of BK-viremia was associated with excellent graft survival at 5-years, low rejection rates and excellent renal function. It is a safe, short and long-term strategy that resulted in freedom from clinically evident BK-virus nephropathy.

Thrombotic Microangiopathy Following Intestinal Transplantation: A Single Center Experience

Background Transplant-related thrombotic microangiopathy (TMA) is a well-recognized complication of all types of transplantations. Despite its known relationship with immunosuppressive therapy, only a few cases have been reported following intestinal transplantation. Methods We retrospectively reviewed the medical files of nine consecutive intestinal transplant patients between 2000 and 2008. Results The diagnosis of TMA was established in 3 patients (33%). At diagnosis the immunosuppressive therapy consisted of tacrolimus (n = 3), combined with azathioprine (n = 1) or sirolimus (n = 2) and steroids (n = 2). The median time between transplantation and TMA was 104 days (range, 55–167 days). Levels of ADAMTS13, a von Willebrand protease, were within normal ranges in all 3 patients. Treatment consisted of stopping/tapering of tacrolimus, together with initiation of plasma therapy, leading to complete remission in all 3 patients. During further follow-up, all 3 patients showed severe graft rejection necessitating more profound immunosuppressive therapy, leading to graft loss in 1 patient and infection-related death in the 2 others. At a median follow-up of 52 months (range, 9–100 months) all remaining TMA-free patients (n = 6) were alive with functioning grafts under minimal immunosuppression. Conclusion Herein we have described 3 intestinal transplant patients who were diagnosed with transplantation-related TMA. Despite excellent disease control the final outcomes were dismal, which clearly contrasts with the outcome among TMA-free patients, who were all well with functioning grafts at last follow-up.

Liver transplant recipients weaned off immunosuppression lack circulating donor-specific antibodies

Human leukocyte antigen (HLA)–specific antibodies (Abs) were examined in 73 clinically stable liver transplant recipients divided into group A (n = 19; clinically tolerant), group B (n = 34; undergoing weaning, on minimal immunosuppression), and group C (n = 20; had failed drug withdrawal or weaning never attempted). Of 19 patients in group A, six (32%) had anti-HLA Abs; none were donor-specific. In contrast, 23 of 34 patients (67%) in group B and nine of 20 patients (45%) in group C exhibited anti-HLA Abs (p = 0.02). Furthermore, 15 of 19 patients in groups B and C (9/12, p = 0.01 and 6/7, p = 0.01, respectively) exhibited donor-specific anti-HLA Abs. The prevalence of donor-specific HLA Abs was significantly higher in nontolerant patients. Five years after initial evaluation, >90% (18/19) group A patients remained off immunosuppression. One of seven of these patients available for retesting exhibited donor-specific Abs. In group B, two-fourths of 34 patients (12%) weaned successfully were HLA-Ab negative; four patients who experienced rejection while undergoing weaning exhibited anti-HLA Ab initially and at 5 years. Thus, most of the liver recipients off immunosuppression lacked donor-specific alloAbs. The occurrence of these alloAbs should now be examined prospectively in a drug weaning trial.

Introduction: Infection in Solid Organ Transplant Recipients

Infectious disease after transplantation remains a field in evolution. Improved immunosuppressive therapies for organ transplantation have reduced the incidence of allograft rejection while increasing susceptibility to opportunistic infections and virally mediated malignancies. Traditional patterns of opportunistic infection after transplantation have also been altered by the emergence of organisms with antimicrobial resistance and by antifungal (including Pneumocystis) and antiviral prophylaxis (i.e. for cytomegalovirus [CMV] and other herpesviruses) (1). Improved microbiologic diagnostic tools (e.g. nucleic acid testing) are used in the routine management of common infections (e.g. CMV, Epstein-Barr virus [EBV]) and have allowed the definition of new clinical syndromes (e.g. BK polyomavirus nephropathy) and of donor-derived infections (e.g. due to lymphocytic choriomeningitis virus [LCMV]). At the same time, a variety of newer techniques are available, largely on a research basis (e.g. HLA-linked tetramer binding, intracellular cytokine staining) to assess pathogen-specific immunity. These may be used to investigate the recipient’s susceptibility to specific infections and are increasingly entering clinical practice. In the past decade, Transplant infectious disease has emerged as an integral subspecialty component of most successful transplant programs.

98-P: Immunosuppression minimization in multivisceral transplant recipients: The impact on global T cell immunity and humoral activity

98-P: Immunosuppression minimization in multivisceral transplant recipients: The impact on global T cell immunity and humoral activity

Sirolimus monotherapy as maintenance immunosuppression: a multicenter experience

The aim of this study was to retrospectively evaluate safety and feasibility of sirolimus (SRL) monotherapy in kidney transplant recipients. Patients older than 18 years, with monotherapy prescribed for more than 1 month and at least 6 months of follow-up were included. We analysed the data from 138 patients. Mean time period between transplantation and start of monotherapy was 6.5 +/- 4.1 years.The most frequent reason was minimization of immunosuppression followed by malignancy. Acute rejection rate was 1.4% at 12 months (two episodes). Graft and patient survival were 94.2% and 97.1% respectively. Mean follow-up after initiation of monotherapy was 29.4 months. Two patients died as a result of cardiovascular diseases and two because of malignancy. Percentage of withdrawal from monotherapy was 14%. SRL trough levels were 10.2 +/- 2.3 ng/ml at baseline and 9.6 6 +/- 3.3 ng/ml at 12 months. Mean glomerular filtration rate was 48.4 ml/min/1.73 m(2) at baseline and 47.7 ml/min/1.73 m(2) at 12 months. Proteinuria was 499.7 mg/24 h at baseline and 543 +/- 794 mg/24 h at 12 months. No significant changes in lipids, glucose, or hemoglobin occurred, although the percentage of patients treated with statins and Epo increased at the end of the follow-up. SRL monotherapy is suitable as long-term immunosuppression in selected patients with no significantly increased risk of late acute rejection.