Comparative effects of sirolimus and mycophenolate mofetil on erythropoiesis in kidney transplant patients

Incidence, Risk Factors, and Outcomes of Posttransplant Erythrocytosis Among Simultaneous Pancreas-Kidney Transplant Recipients

Background

Posttransplant erythrocytosis (PTE) is a well-known complication of kidney transplantation. However, the risk and outcomes of PTE among simultaneous pancreas-kidney transplant (SPKT) recipients are poorly described.

Methods

We analyzed all SPKT recipients at our center between 1998 and 2021. PTE was defined as at least 2 consecutive hematocrit levels of >51% within the first 2 y of transplant. Controls were selected at a ratio of 3:1 at the time of PTE occurrence using event density sampling. Risk factors for PTE and post-PTE graft survival were identified.

Results

Of 887 SPKT recipients, 108 (12%) developed PTE at a median of 273 d (interquartile range, 160-393) after transplantation. The incidence rate of PTE was 7.5 per 100 person-years. Multivariate analysis found pretransplant dialysis (hazard ratio [HR]: 3.15; 95% confidence interval [CI], 1.67-5.92; P < 0.001), non-White donor (HR: 2.14; 95% CI, 1.25-3.66; P = 0.01), female donor (HR: 1.50; 95% CI, 1.0-2.26; P = 0.05), and male recipient (HR: 2.33; 95% CI, 1.43-3.70; P = 0.001) to be associated with increased risk. The 108 cases of PTE were compared with 324 controls. PTE was not associated with subsequent pancreas graft failure (HR: 1.36; 95% CI, 0.51-3.68; P = 0.53) or kidney graft failure (HR: 1.16; 95% CI, 0.40-3.42; P = 0.78).

Conclusions

PTE is a common complication among SPKT recipients, even in the modern era of immunosuppression. PTE among SPKT recipients was not associated with adverse graft outcomes, likely due to appropriate management.

Is Erythrocytosis More Common After Simultaneous Pancreas Kidney Transplantation? A Single-Center Experience

Post-transplant erythrocytosis (PTE) is reported in 8% to 22% of kidney transplant recipients. Few studies have evaluated the prevalence of PTE in simultaneous kidney-pancreas transplantation (SPKT). This study aimed to evaluate the prevalence of PTE in a cohort of SPKT and same-donor single kidney transplant patients and find predictive factors for erythrocytosis development. A single-center retrospective cohort study was performed with 65 SPKT recipients and 65 same-donor single kidney transplant patients. Post-transplant erythrocytosis was defined as a hematocrit persistently >51% without a known cause of erythrocytosis. The PTE prevalence was 23.1% and was more frequent in SPKT patients than in single donor patients (38.5% vs 7.7%; P < .001). The mean time for PTE development was 11.2 ± 13.3 months. In the multivariate model, SPKT was the only predictor for PTE development. De novo hypertension was more frequent in the PTE group (P = .002), but there was no difference in stroke and pancreatic or kidney thrombosis occurrence. Post-transplant erythrocytosis is more common after SPKT than after single kidney transplantation. De novo hypertension was more frequent in the erythrocytosis group, but allograft thrombosis rates.

The current therapeutic approach for anaemia after kidney transplant

PURPOSE OF REVIEW

Anaemia after kidney transplantation is a common finding with no uniform management guideline. Most approaches are derived from the chronic kidney disease (CKD) population. Recent advances for the treatment of anaemia in patients with CKD/End stage renal disease include hypoxia-inducible factor-prolyl hydroxylase inhibitor (HIF-PHi), a novel class of oral erythropoietin-stimulating agents (ESAs). We present relevant studies of HIF-PHi in the transplant population and its implications on the management of posttransplant anaemia.

RECENT FINDINGS

Data on HIF-PHi use in the kidney transplant population are promising. Limited data demonstrate a significant increase in haemoglobin, with a comparable safety profile to epoetin. Reported adverse effects include overcorrection and low iron stores.

SUMMARY

Current therapeutic approaches to anaemia in the kidney transplant population is mostly derived from the CKD population. More studies are needed on HIF-Phi, a novel class of ESAs that has thus far demonstrated promise in the kidney transplant population.

mTOR Inhibitors Induce Erythropoietin Resistance in Renal Transplant Recipients

Aim

To elucidate the role of mTOR inhibitors on iron, hepcidin and erythropoietin-mediated regulation of hemopoiesis in stable renal transplant recipients (RTR).

Background

Impaired hemopoiesis is common following renal transplantation managed using mTOR inhibitors. The mechanisms responsible are uncertain but include direct effects on iron, hepcidin or erythropoietin-mediated hemopoiesis.

Methods

We conducted a single center prospective case-control study of 26 adult RTR with stable allograft function. RTR received stable mTOR dosing (cases, 11/26 [42%]) or stable tacrolimus dosing (controls, 15/26 [58%]). Baseline demographics, full blood count, renal function, iron studies, hepcidin-25, Interleukin-6 (IL-6) and erythropoietin (EPO) levels were determined.

Results

There were no differences in age, gender or allograft function. Mean daily sirolimus dose for cases was 1.72 mg, with mean trough level of 8.46 ng/mL. Mean daily tacrolimus dose for controls was 4.3 mg, with mean trough level of 5.8 ng/mL. There were no differences in mean hemoglobin (143 vs. 147 g/L; p = 0.59), MCV (88 vs. 90 fL; p = 0.35), serum ferritin (150 vs. 85.7 μg/L; p = 0.06), transferrin saturation (26 vs. 23.3%; p = 0.46), IL-6 (11 vs. 7.02 pg/ml; p = 0.14) or hepcidin-25 (3.62 vs. 3.26 nM; p = 0.76) between the groups. EPO levels were significantly higher in the group receiving mTOR therapy (16.8 vs. 8.49 IU/L; p = 0.028). On logistic regression analysis EPO level was the only variable that had a significant impact providing an odds ratio of 0.84 (95%CI 0.66–0.98). The area under the receiver operator characteristic curve (ROC) for the analysis was 0.77 (95%CI 0.54–0.94) with p = 0.04.

Conclusion: Higher levels of EPO in the absence of deranged iron biochemistry or hepcidin-25 levels suggest that EPO resistance rather than impaired iron metabolism may contribute to the impaired hemopoiesis previously demonstrated in RTR on mTOR therapy.

Post-transplant erythrocytosis after kidney transplantation: A review

Post-transplant erythrocytosis (PTE) is defined as persistently elevated hemoglobin > 17 g/dL or hematocrit levels > 51% following kidney transplantation, independent of duration. It is a relatively common complication within 8 months to 24 months post-transplantation, occurring in 8%-15% of kidney transplant recipients. Established PTE risk factors include male gender, normal hemoglobin/hematocrit pre-transplant (suggestive of robust native kidney erythropoietin production), renal artery stenosis, patients with a well-functioning graft, and dialysis before transplantation. Many factors play a role in the development of PTE, however, underlying endogenous erythropoietin secretion pre-and post-transplant is significant. Other contributory factors include the renin-angiotensin- aldosterone system, insulin-like growth factors, endogenous androgens, and local renal hypoxia. Most patients with PTE experience mild symptoms like malaise, headache, fatigue, and dizziness. While prior investigations showed an increased risk of thromboembolic events, more recent evidence tells a different story-that PTE perhaps has lessened risk of thromboembolic events or negative graft outcomes than previously thought. In the evaluation of PTE, it is important to exclude other causes of erythrocytosis including malignancy before treatment. Angiotensin converting enzyme inhibitors (ACE-I) and angiotensin receptor blockers (ARBs) are the mainstays of treatment. Increased ACE-I/ARB use has likely contributed to the falling incidence of erythrocytosis. In this review article, we summarize the current literature in the field of post-transplant erythrocytosis after kidney transplantation.

Contemporary incidence and risk factors of post transplant Erythrocytosis in deceased donor kidney transplantation

BACKGROUND

Post-Transplant erythrocytosis (PTE) has not been studied in large recent cohorts. In this study, we evaluated the incidence, risk factors, and outcome of PTE with current transplant practices using the present World Health Organization criteria to define erythrocytosis. We also tested the hypothesis that the risk of PTE is greater with higher-quality kidneys.

METHODS

We utilized the Deceased Donor Study which is an ongoing, multicenter, observational study of deceased donors and their kidney recipients that were transplanted between 2010 and 2013 across 13 centers. Eryrthocytosis is defined by hemoglobin> 16.5 g/dL in men and> 16 g/dL in women. Kidney quality is measured by Kidney Donor Profile Index (KDPI).

RESULTS

Of the 1123 recipients qualified to be in this study, PTE was observed at a median of 18 months in 75 (6.6%) recipients. Compared to recipients without PTE, those with PTE were younger [mean 48±11 vs 54±13 years, p < 0.001], more likely to have polycystic kidney disease [17% vs 6%, p < 0.001], have received kidneys from younger donors [36 ±13 vs 41±15 years], and be on RAAS inhibitors [35% vs 22%, p < 0.001]. Recipients with PTE were less likely to have received kidneys from donors with hypertension [16% vs 32%, p = 0.004], diabetes [1% vs 11%, p = 0.008], and cerebrovascular event (24% vs 36%, p = 0.036). Higher KDPI was associated with decreased PTE risk [HR 0.98 (95% CI: 0.97-0.99)]. Over 60 months of follow-up, only 17 (36%) recipients had sustained PTE. There was no association between PTE and graft failure or mortality, CONCLUSIONS: The incidence of PTE was low in our study and PTE resolved in majority of patients. Lower KDPI increases risk of PTE. The underutilization of RAAS inhibitors in PTE patients raises the possibility of under-recognition of this phenomenon and should be explored in future studies.

CD80 Insights as Therapeutic Target in the Current and Future Treatment Options of Frequent-Relapse Minimal Change Disease

Minimal change disease (MCD) is the most common cause of idiopathic nephrotic syndrome in children, and it is well known for its multifactorial causes which are the manifestation of the disease. Proteinuria is an early consequence of podocyte injury and a typical sign of kidney disease. Steroid-sensitive patients react well with glucocorticoids, but there is a high chance of multiple relapses. CD80, also known as B7-1, is generally expressed on antigen-presenting cells (APCs) in steroid-sensitive MCD patients. Various glomerular disease models associated with proteinuria demonstrated that the detection of CD80 with the increase of urinary CD80 was strongly associated closely with frequent-relapse MCD patients. The role of CD80 in MCD became controversial because one contradicts finding. This review covers the treatment alternatives for MCD with the insight of CD80 as a potential therapeutic target. The promising effectiveness of CD20 (rituximab) antibody and CD80 inhibitor (abatacept) encourages further investigation of CD80 as a therapeutic target in frequent-relapse MCD patients. Therapeutic-based antibody towards CD80 (galiximab) had never been investigated in MCD or any kidney-related disease; hence, the role of CD80 is still undetermined. A new therapeutic approach towards MCD is essential to provide broader effective treatment options besides the general immunosuppressive agents with gruesome adverse effects.

Sirolimus and mTOR Inhibitors: A Review of Side Effects and Specific Management in Solid Organ Transplantation

Inhibitors of mechanistic target of rapamycin (mTOR inhibitors) are used as antiproliferative immunosuppressive drugs and have many clinical applications in various drug combinations. Experience in transplantation studies has been gained regarding the side effect profile of these drugs and the potential benefits and limitations compared with other immunosuppressive agents. This article reviews the adverse effects of mTOR inhibitors in solid organ transplantation, with special attention given to mechanisms hypothesized to cause adverse events and their management strategies.

Post renal transplant anemia: severity, causes and their association with graft and patient survival

Background

Post transplantation anemia (PTA) is common among kidney transplant patients. PTA is associated with increased graft loss and in most studies with increased mortality. However, the effect of the severity of anemia on this associations was not thoroughly evaluated.

Methods

Patients who underwent kidney transplantation in Rabin Medical Center (RMC) were included in the study. Data were collected during the years 2002–2016. Anemia was defined as hemoglobin (Hb) level less than 12 g/dL in women and less than 13 g/dL in men, in accordance with World Health Organization (WHO) criteria. Severe anemia was defined as hemoglobin lower than 11 g/dL. Primary outcome was a composite of patient and graft survival. We used univariate and multivariate models to evaluate association between severity and specific causes of anemia with the outcomes. As the risk associated with anemia changed over time we analyzed the risk separately for the early and the late period (before and after 1251 days).

Results

Our cohort included 1139 patients, 412 (36.2%) of which had PTA and 134 (11.7%) had severe anemia. On multivariable analysis, severe anemia was highly associated with the primary outcome at the early period (HR 6.26, 95% CI 3.74–10.5, p < 0.001). Anemia due to either AKI & acute rejection (11.9% of patients) or infection (16.7%), were associated with primary outcome at the early period (HR 9.32, 95% CI 5.3–26.41, p < 0.001 and HR 3.99, 95% CI 2.01–7.95, p < 0.001, respectively). There was non-significant trend for association between anemia due to Nutritional deficiencies (29.1%) and this outcome (HR 3.07, 95% CI 0.93–10.17, p = 0.067).

Conclusion

PTA is associated with graft loss and mortality especially during the first three years. Anemia severity affects this association. An anemia workup is recommended for PTA.

Electronic supplementary material

The online version of this article (10.1186/s12882-019-1244-y) contains supplementary material, which is available to authorized users.

Drug-Induced Hematological Cytopenia in Kidney Transplantation and the Challenges It Poses for Kidney Transplant Physicians

Drug-induced hematological cytopenia is common in kidney transplantation. Various cytopenia including leucopenia (neutropenia), thrombocytopenia, and anemia can occur in kidney transplant recipients. Persistent severe leucopenia or neutropenia can lead to opportunistic infections of various etiologies. On the contrary, reducing or stopping immunosuppressive medications in these events can provoke a rejection. Transplant clinicians are often faced with the delicate dilemma of balancing cytopenia and rejection from adjustments of immunosuppressive regimen. Differentials of drug-induced cytopenia are wide. Identification of culprit medication and subsequent modification is also challenging. In this review, we will discuss individual drug implicated in causing cytopenia and correlate it with corresponding literature evidence.

miR-144/451 represses the LKB1/AMPK/mTOR pathway to promote red cell precursor survival during recovery from acute anemia

The microRNAs miR-144 and -451 are encoded by a bicistronic gene that is strongly induced during red blood cell formation (erythropoiesis). Ablation of the miR-144/451 gene in mice causes mild anemia under baseline conditions. Here we show that miR-144/451^−/− erythroblasts exhibit increased apoptosis during recovery from acute anemia. Mechanistically, miR-144/451 depletion increases the expression of the miR-451 target mRNA Cab39, which encodes a co-factor for the serine-threonine kinase LKB1. During erythropoietic stress, miR-144/451^−/− erythroblasts exhibit abnormally increased Cab39 protein, which activates LKB1 and its downstream AMPK/mTOR effector pathway. Suppression of this pathway via drugs or shRNAs enhances survival of the mutant erythroblasts. Thus, miR-144/451 facilitates recovery from acute anemia by repressing Cab39/AMPK/mTOR. Our findings suggest that miR-144/451 is a key protector of erythroblasts during pathological states associated with dramatically increased erythropoietic demand, including acute blood loss and hemolytic anemia.

Renal association clinical practice guideline on Anaemia of Chronic Kidney Disease

Anaemia is a commonly diagnosed complication among patients suffering with chronic kidney disease. If left untreated, it may affect patient quality of life. There are several causes for anaemia in this patient population. As the kidney function deteriorates, together with medications and dietary restrictions, patients may develop iron deficiency, resulting in reduction of iron supply to the bone marrow (which is the body organ responsible for the production of different blood elements). Chronic kidney disease patients may not be able to utilise their own body's iron stores effectively and hence, many patients, particularly those receiving haemodialysis, may require additional iron treatment, usually provided by infusion.With further weakening of kidney function, patients with chronic kidney disease may need additional treatment with a substance called erythropoietin which drives the bone marrow to produce its own blood. This substance, which is naturally produced by the kidneys, becomes relatively deficient in patients with chronic kidney disease. Any patients will eventually require treatment with erythropoietin or similar products that are given by injection.Over the last few years, several iron and erythropoietin products have been licensed for treating anaemia in chronic kidney disease patients. In addition, several publications discussed the benefits of each treatment and possible risks associated with long term treatment. The current guidelines provide advice to health care professionals on how to screen chronic kidney disease patients for anaemia, which patients to investigate for other causes of anaemia, when and how to treat patients with different medications, how to ensure safe prescribing of treatment and how to diagnose and manage complications associated with anaemia and the drugs used for its treatment.

Systemic meta-analysis assessing the short term applicability of early conversion to mammalian target of rapamycin inhibitors in kidney transplant

AIM

To consolidate the present evidence of effectiveness in renal functioning and graft survival following early introduction of mammalian target of rapamycin (mTOR) inhibitors with or without calcineurin inhibitors (CNIs) in renal transplant recipients.

METHODS

We analysed the current literature following PROSPERO approval describing the role of immunosuppressive agent, mTOR inhibitors as an alternative to CNI within six months of renal transplant by searching the PubMed, EMBASE, Cochrane, Crossref, and Scopus using MeSH terms.

RESULTS

Six articles of early withdrawal of CNI and introduction of mTOR-inhibitors within six months of renal transplantation were sought. Glomerular filtration rate (GFR) and serum creatinine were significantly better in mTOR inhibitor group with equivalent survival at 12 mo, even though Biopsy Proven Acute rejection was significantly higher in mTOR-inhibitor group.

CONCLUSION

The evidence reviewed in this meta-analysis suggests that early introduction mTOR-inhibitors substantial CNI minimization. The mTOR inhibitors such as everolimus and sirolimus, due to their complementary mechanism of action and favourable nephrotoxicity profile; better glomerular filtration, lower serum creatinine with equivalent survival. Having said that, due to the higher rejection rate, may influence the use of these regimens to patients with moderate to high immunological risk patients.

Posttransplant Anemia as a Prognostic Factor of Mortality in Kidney-Transplant Recipients

Background. Findings on the association between posttransplant anemia (PTA) and mortality in posttransplant patients are scarce. This study explored whether PTA shortly after kidney transplantation (KT) predicts mortality at up to 10 years' follow-up, stratified for chronic kidney disease (CKD) stages. Methods. PTA was divided into 3 categories according to the hemoglobin (Hb) value: severe (Hb < 10 g/dl), mild (10.0 g/dl ≤ Hb < 11.9 g/dl), or no PTA (Hb ≥ 12 g/dl). CKD stages were estimated using the CKD-EPI formula and divided into 2 groups: CKD1-2 and CKD3-5. Cox regression, stratified according to CKD, was performed to identify whether different categories of PTA predicted mortality in KT recipients. Results. Age, being female, and both mild and severe PTA contributed significantly to the Cox regression model on mortality in CKD1-2. In the Cox regression model for mortality in CKD3-5, age and severe PTA contributed significantly to this model. Conclusion. PTA shortly after KT increased the risk of mortality at up to 10 years' follow-up. Even mild PTA is associated with a 6-fold higher risk of mortality and severe PTA with a 10-fold higher risk of mortality in CKD1-2. Clinical evaluation and treatment of anemia might reduce the higher risk of mortality in patients with PTA in early stages of CKD after KT.

Efficacy and safety of early tacrolimus conversion to sirolimus after kidney transplantation: Long-term results of a prospective randomized study

We report a prospective, open-label, randomized study to evaluate the safety and efficacy of converting patients with a stable renal function from tacrolimus (Tac)-based regimen to a sirolimus (SRL)-based regimen after kidney transplantation. Fifty-eight low-risk renal allograft recipients who receiving Tac 6 months posttransplant, were randomly assigned to continue Tac (n = 29) or convert to SRL (n = 29). We evaluated the 3-year outcomes including patient and graft survival, graft function, and safety profile. Three-year patient and graft survival in SRL and Tac groups were 93.1% versus 100% (P = 0.32), and 89.7% versus 100% (P = 0.11), respectively. However, the SRL group had a significantly better renal function, from the 2^nd year posttransplant until the last follow-up. Four (13.8%) patients in the SRL group and 3 (10.3%) in the Tac group (P = 0.5) developed biopsy-proven acute rejection. Mean urinary protein excretion increased significantly after SRL conversion. Diastolic blood pressure was significantly lower at the end of the study in patients who eliminated Tac (80.4 vs. 75.6 mmHg in Tac and SRL group, respectively) (P = 0.03). Mean hemoglobin concentrations decreased after SRL conversion and remained significantly lower from 12 months to 36 months (P = 0.01). The mean serum cholesterol (540 ± 44 mg/dl) and triglyceride (177 ± 27 mg/dl) increased significantly in the SRL group, compared to Tac group (487 ± 62 mg/dl) (P = 0.03) and (141 ± 26 mg/dl) (P = 0.04). Our experience demonstrates that conversion to SRL from calcineurin inhibitors-based therapy may result in better renal function and blood pressure control in renal transplant recipients without an increased risk of acute rejection. However, these benefits have not resulted in a growing advantage in graft or patient survival.

Anemia and Immunosuppressive Regimen in Renal Transplanted Patients: Single-Center Retrospective Study

We compared retrospectively the level of hemoglobin and the percentage of patients with anemia among 59 kidney transplant recipients receiving everolimus, cyclosporine, and corticosteroids and 128 treated with cyclosporine, mycophenolic acid, and corticosteroids. We also compared age at the time of transplantation, sex and ferritine, serum creatinine, creatinine clearance, folic acid, cyanocobalamine levels, use od recombinant erythropoietin, mean corpuscolar volume at the last ambulatory control. Statistical analysis included Student t test, χ(2) test, and logistic regression. The analysis was performed using SPSS software. We observed no difference in terms of hemoglobin levels in patients treated with everolimus (12.9 ± 1.6 vs 12.7 ± 1.5 g/dL). Anemia (defined as hemoglobin <13 g/dL in men and <12 g/dL in women, or need to use erythropoietin) was found in 49% and 45% of patients in the 2 groups respectively (P = .6). The other parameters evaluated were similar except for the mean corpuscular volume, which was significantly lower in the everolimus group. In the multivariate analysis only serum creatinine and estimated glomerular filtration rate influenced the level of hemoglobin. We observed no differences in terms of development of anemia in renal transplanted patients treated with everolimus-based regimen.

Safety of mTOR inhibitors in adult solid organ transplantation

INTRODUCTION

Mammalian target of rapamycin (mTOR) inhibitors (sirolimus and everolimus) are a class of immunosuppressive drugs approved for solid organ transplantation (SOT). By inhibiting the ubiquitous mTOR pathway, they present a peculiar safety profile. The increased incidence of serious adverse events in early studies halted the enthusiasm as a kidney sparing alternative to calcineurin inhibitors (CNI).

AREAS COVERED

Herein we review mTOR inhibitors safety profile for adult organ transplantation, ranging from acute side effects, such as lymphoceles, delayed wound healing, or cytopenias, to long-term ones which increase morbidity and mortality, such as cancer risk and metabolic profile. Infection, proteinuria, and cutaneous safety profiles are also addressed.

EXPERT OPINION

In the authors' opinion, mTOR inhibitors are a safe alternative to standard immunosuppression therapy with CNI and mycophenolate/azathioprine. Mild adverse events can be easily managed with an increased awareness and close monitoring of trough levels. Most serious side effects are dose- and organ-dependent. In kidney and heart transplantation mTOR inhibitors may be safely used as either low-dose de novo or through early-conversion. In the liver, conversion 4 weeks post-transplantation may reduce long-term chronic kidney disease secondary to calcineurin nephrotoxicity, without increasing hepatic artery/portal vein thrombosis.

Anemia has a negative impact on self-rated health in kidney transplant recipients with well-functioning grafts: findings from an 8-year follow-up study

PURPOSE

Anemia is a predictor of mortality and of self-rated health (SRH). However, studies on the relationship between SRH and changes in hemoglobin (Hb) value over time stratified by chronic kidney disease (CKD) stages are lacking. The aim is to explore whether a change in Hb-value over time associates with SRH at up to 8-year follow-up, stratified for CKD stages.

METHODS

A prospective study with a baseline measurement between the 3rd and 12th month after KT was performed on 337 consecutive patients. Demographic and clinical data were retrieved from medical records. CKD stages were estimated using the CKD-EPI formula and divided into two groups: CKD1-2 and CKD3-5. Generalized estimating equations (GEE) were performed to identify associations of SRH at follow-up in both CKD groups.

RESULTS

Male gender, new-onset diabetes mellitus after KT (NODAT), a decrease in estimated glomerular filtration rate (eGFR) and Hb-value over time contributed significantly to the GEE model on SRH at follow-up in CKD1-2. For SRH at follow-up in CKD3-5, older age, male gender and chronic renal allograft dysfunction (CRAD) contributed significantly to the GEE model.

CONCLUSIONS

At up to 8-year follow-up, male gender, NODAT, a decrease in eGFR and Hb-value over time are associated with poorer SRH in CKD1-2. In such patients, we suggest monitoring slight deteriorations in eGFR and Hb-values. In CKD3-5, higher age, male gender and higher presence of CRAD are associated with poorer SRH at up to 8-year follow-up. In these patients, adequate treatment would slow down CRAD progression.

mTOR inhibitors and renal allograft: Yin and Yang

Mammalian target of rapamycin inhibitors (mTOR-I), everolimus and sirolimus, are immunosuppressive drugs extensively used in renal transplantation. Their main mechanism of action is the inhibition of cell signaling through the PI3 K/Akt/mTOR pathway. This interesting mechanism of action confers to these medications both great immunosuppressive potential and important anti-neoplastic properties. Although the clinical utility of this drug category, as with other antineoplastic/immunosuppressants, is clear, the use of mTOR-I commonly results in the development of several complications. In particular, these agents may determine severe renal toxicity that, as recent studies report, seems clearly correlated to dose and duration of drug use. The mTOR-I-induced renal allograft spectrum of toxicity includes the enhanced incidence of delayed graft function, nephrotoxicity in particular when co-administered with calcineurin inhibitors (CNI) and onset of proteinuria. The latter effect appears highly frequent in patients undergoing mTOR-I treatment and significantly associated with a rapid graft lost. The damage leading to this complication interests both the glomerular and tubular area. mTOR-I cause an inhibition of proliferation in podocytes and the epithelial-to-mesenchymal transition in tubular cells. Interestingly, all these side effects are mostly reversible and dose related. Therefore, it is unquestionable that these particular drugs should be administered at the lowest dose able to maintain relatively low trough levels, in order to maximize their important and specific therapeutic effects while minimizing or avoiding drug toxicities. Utilization of low dosages of mTOR-I should be encouraged not only in CNI-combined schemas, but also when administered alone in a CNI-free immunosuppressive protocol.

Mycophenolate mofetil enhances the negative effects of sirolimus and tacrolimus on rat kidney cell metabolism

Background and Purpose

Mycophenolate mofetil (MMF) per se is not known to have negative effects on the kidney. MMF alone or in combination with sirolimus, can be the basis of calcineurin inhibitor (CNI)-free, kidney sparing drug protocols. However, long-term outcomes in patients on MMF/SRL seem to be inferior to those treated with regimens that include the CNI tacrolimus (TAC) due to an increased risk of allo-immune reactions. Interestingly, potential enhancement of the negative effects of SRL and TAC on the kidney by MMF has never been considered.

Experimental Approach

It was our aim to study the effects of TAC, SRL and MMF alone and evaluate their interactions when combined on the rat kidney. For this purpose we used a comprehensive molecular marker approach including measurements of urinary 8-isoprostane concentrations (oxidative stress marker) and changes of urinary metabolite patterns (¹H-NMR spectroscopy) and comparing these markers to renal function (glomerular filtration rate (GFR)) and morphologic alterations (histology).

Key Results

While MMF alone did not impact GFR, its interaction with SRL and TAC led to a significant decrease of rats’ renal function. The decline went in parallel with a significant increase in urinary isoprostane concentrations and an enhancement of negative effects on urinary metabolite patterns.

Conclusions

In broad summary, the present study showed that MMF may enhance the negative effects of TAC on kidney function and may even display nephrotoxic properties when combined with SRL.

Blood disorders after kidney transplantation

Post transplant anemia (PTA) is a common issue in kidney transplant recipients. Most importantly it is associated with an impaired allograft function. Other important factors associated with PTA are immunosuppressive drugs (MPA, AZA and SRL), iron deficiency, infections (Parvo B19), older donor age, rejection episodes, an increased inflammatory state, and erythropoietin hyporesponsiveness. As there are no adequately powered RCTs in the kidney transplant population on anemia treatment with ESA, we have to rely on what we know from the large RCTs in the CKD population. The recently published KDIGO guidelines do not recommend treatment with ESA if Hb is >10 g/dl. Repletion of iron stores is emphasized. Post transplant leukopenia (PTL) and thrombocytopenia (PTT) are frequent complications especially in the first six months after kidney transplantation. Myelosuppression caused by immunosuppressive agents (MPA, AZA, SRL, rATG), antimicrobial drugs (VGCV), and CMV infection is the predominant cause. There are no widely accepted guidelines on treatment strategies, but most often dose reduction or discontinuation of causative medication is done. Most clinicians tend to decrease MPA dose, but this is eventually associated with an increase in acute rejection episodes. VGCV dose reduction (preemptive treatment instead of CMV prophylaxis) may be a successful strategy. In severe cases G-CSF treatment is an important management option and seems to be safe.

Systemic and nonrenal adverse effects occurring in renal transplant patients treated with mTOR inhibitors

The mammalian target of rapamycin inhibitors (mTOR-I), sirolimus and everolimus, are immunosuppressive drugs largely used in renal transplantation. The main mechanism of action of these drugs is the inhibition of the mammalian target of rapamycin (mTOR), a regulatory protein kinase involved in lymphocyte proliferation. Additionally, the inhibition of the crosstalk among mTORC1, mTORC2, and PI3K confers the antineoplastic activities of these drugs. Because of their specific pharmacological characteristics and their relative lack of nephrotoxicity, these inhibitors are valid option to calcineurine inhibitors (CNIs) for maintenance immunosuppression in renal transplant recipients with chronic allograft nephropathy. However, as other immunosuppressive drugs, mTOR-I may induce the development of several adverse effects that need to be early recognized and treated to avoid severe illness in renal transplant patients. In particular, mTOR-I may induce systemic nonnephrological side effects including pulmonary toxicity, hematological disorders, dysmetabolism, lymphedema, stomatitis, cutaneous adverse effects, and fertility/gonadic toxicity. Although most of the adverse effects are dose related, it is extremely important for clinicians to early recognize them in order to reduce dosage or discontinue mTOR-I treatment avoiding the onset and development of severe clinical complications.

Iron metabolism, hepcidin, and anemia in orthotopic heart transplantation recipients treated with mammalian target of rapamycin

PURPOSE

Functional iron deficiency is characterized by the presence of adequate stores as defined by conventional criteria, but with the inability to sufficiently mobilize iron for erythropoiesis. Hepcidin, produced by hepatocytes in response to anemia, hypoxia, or inflammation, is a key regulator of iron homeostasis. Anemia is relatively common among patients treated with mammalian target of rapamycin (mTOR) antagonists. We tested hypothesis that hepcidin was related to the functional iron deficiency, defined as a ferritin value above 200 ng/mL with transform saturation (TSAT) below 20% among orthotopic heart transplant recipients (OHT) treated (n = 35) versus not treated (n = 134) with mTOR.

METHODS AND MATERIALS

Using standard laboratory methods we assessed iron status: serum iron, total iron binding capacity, ferritin, TSAT, complete blood count and creatinine. Soluble transferrin receptor (sTFR), high sensitivity C-reactive protein (hSCRP), interleukin-6 (IL-6) hepcidin, and cystatin C were measured using commercially available kits.

RESULTS

According to the World Health Organization definition, the prevalence of anemia was 51% among mTOR treated whereas in the rest of the OHT the prevalence of anemia 30% among the other OHT patients. Functional iron deficiency was present in 80% of mTOR-treated patients. Serum hepcidin, IL-6, hsCRP, serum creatinine, cystatin C, NT-proBNP were significantly higher among mTOR treated patients; whereas sTFR, estimated glomerular filtration rate, hemoglobin, and erythrocyte count were significantly lower.

CONCLUSIONS

Functional iron deficiency which is common among OHT patients treated with mTOR, was associated with high hepcidin levels and inflammatory markers. This form of anemia in mTOR-treated OHT resembles the disorder of chronic disease, suggesting that OHT patients show low-grade inflammation, which should be investigated for underlying, potentially reversible causes. Iron treatment should also be considered.

Association of sirolimus adverse effects with m-TOR, p70S6K or Raptor polymorphisms in kidney transplant recipients

BACKGROUND

The mammalian target of rapamycin (m-TOR) inhibitor sirolimus is an immunosuppressive drug used in kidney transplantation. m-TOR binds with Raptor and phosphorylates p70S6 kinase, a protein involved in numerous cell signalling pathways. We examined the association of candidate polymorphisms in m-TOR, Raptor and p70S6K, sirolimus dose and exposure, and other time-independent as well as time-dependent covariates, with sirolimus-induced adverse events in kidney transplant recipients.

METHODS

This study included a first group of 113 patients, switched from a calcineurin inhibitor to sirolimus, and a validation group of 66 patients from another clinical trial, with the same immunosuppressive regimen. The effects of gene polymorphisms and covariates on the total cholesterol, LDL cholesterol, triglycerides, haemoglobin, cutaneous adverse events, oedemas and infections were studied using multilinear regression, or logistic regression imbedded in linear mixed-effect models.

RESULTS

An m-TOR variant haplotype was significantly associated with a decrease in haemoglobin levels in the two populations of patients (discovery group: β=-0.82 g/dl, P=0.0076; validation group: β=-1.58 g/dl, P=0.0308). Increased sirolimus trough levels were significantly associated with increased total cholesterol levels (discovery group: β=0.02 g/l, P<0.0001; validation group: β=0.02 g/l, P=0.0002) and triglyceride levels (discovery group: β=0.02 g/l, P=0.0059; validation group: β=0.05 g/l, P=0.0370). Sirolimus trough levels were also associated with an increased risk for cutaneous adverse events [odds ratio=1.97, 95% confidence interval (1.32-1.94), P=0.0009] and oedemas [odds ratio=1.16, 95% confidence interval (1.03-1.30), P=0.01342] in the discovery group, but this was not confirmed in the validation group.

CONCLUSION

These results provide evidence of an association between an m-TOR haplotype and a decrease in haemoglobin in renal transplant recipients.

Anemia and erythrocytosis in patients after kidney transplantation

Anemia is a highly prevalent disorder in recipients of renal allografts. Despite its frequent occurrence, there is still uncertainty with regard to treatment targets and treatment options. This includes questions on appropriate iron management, the choice and dosage of erythropoietin stimulating agents, criteria for the timing of treatment initiation and the targeted hemoglobin values. The review summarizes available data on recent therapeutic strategies for post transplant anemia, as well as for post transplant erythrocytosis, another hematological disorder, that has decreased in recent years.

Mammalian target of rapamycin (mTOR) inhibitors: potential uses and a review of haematological adverse effects

Mammalian target of rapamycin (mTOR) inhibitors (mTORis) constitute a relatively new category of immunosuppressive and antineoplastic drugs. These share a unique mechanism of action that is focused on the inhibition of the mTOR. Their clinical applications have recently expanded significantly to cover a wide spectrum of immune and non-immune-mediated disorders, including, apart from solid organ transplantation, various solid organ and haematological malignancies, rheumatological and auto-immune diseases such as rheumatoid arthritis, systemic lupus erythematosus, fibrotic conditions, e.g. pulmonary and hepatic fibrosis, and even metabolic problems such as diabetes mellitus and obesity. The most challenging and frequent adverse effects of the mTORis are the haematological ones, especially anaemia, leukopenia and thrombocytopenia. A unique characteristic of mTORi-induced anaemia is concurrent marked microcytosis. Recently, mechanisms have been proposed to explain the microcytic appearance of this anaemia; these include globin production defect, erythropoietin resistance, chronic inflammation, dysregulation of cellular iron metabolism and hepcidin-mediated iron homeostasis interference. As the differential diagnosis of microcytic anaemia includes pure iron deficiency, functional iron deficiency and haemoglobinopathies, characterization of the anaemia requires significant investigation, time and costs. Therefore, understanding of the likely interaction between mTORis and patients is valuable in clinical practice. Moreover, this could expand the drugs' therapeutic applications to other disorders, and suggest novel targets for further research.

Mammalian target of rapamycin (mTOR) inhibitors: potential uses and a review of haematological adverse effects

Mammalian target of rapamycin (mTOR) inhibitors (mTORis) constitute a relatively new category of immunosuppressive and antineoplastic drugs. These share a unique mechanism of action that is focused on the inhibition of the mTOR. Their clinical applications have recently expanded significantly to cover a wide spectrum of immune and non-immune-mediated disorders, including, apart from solid organ transplantation, various solid organ and haematological malignancies, rheumatological and auto-immune diseases such as rheumatoid arthritis, systemic lupus erythematosus, fibrotic conditions, e.g. pulmonary and hepatic fibrosis, and even metabolic problems such as diabetes mellitus and obesity. The most challenging and frequent adverse effects of the mTORis are the haematological ones, especially anaemia, leukopenia and thrombocytopenia. A unique characteristic of mTORi-induced anaemia is concurrent marked microcytosis. Recently, mechanisms have been proposed to explain the microcytic appearance of this anaemia; these include globin production defect, erythropoietin resistance, chronic inflammation, dysregulation of cellular iron metabolism and hepcidin-mediated iron homeostasis interference. As the differential diagnosis of microcytic anaemia includes pure iron deficiency, functional iron deficiency and haemoglobinopathies, characterization of the anaemia requires significant investigation, time and costs. Therefore, understanding of the likely interaction between mTORis and patients is valuable in clinical practice. Moreover, this could expand the drugs' therapeutic applications to other disorders, and suggest novel targets for further research.

mTOR inhibition and erythropoiesis: microcytosis or anaemia?

BACKGROUND

Anaemia and microcytosis are common post kidney transplantation. The aim of this study was to evaluate the potential role of mammalian target of rapamycin (mTOR) inhibition in the development of anaemia and microcytosis in healthy animals and in human erythroid cultures in vitro.

METHODS

Rats with normal kidney function were treated with sirolimus (n = 7) or vehicle (n = 8) for 15 weeks. Hemograms were determined thereafter. In the sirolimus withdrawal part of the study, rats received sirolimus (SRL) for 67 days (n = 4) 1 mg/kg three times per week or for 30 days (n = 4) and were observed until Day 120. Hemograms were performed regularly. Peripheral blood mononuclear cells from healthy controls (HC; n = 8), kidney transplant patients with sirolimus treatment with (SRL + MC; n = 8) or without microcytosis (SRL - MC; n = 8) were isolated and cultured in the absence or presence of SRL (5 ng/mL).

RESULTS

SRL-treated animals had a reduced mean corpuscular volume (MCV) and elevated erythrocyte count compared with control animals after 15 weeks of treatment. This effect was evident as early as 4 weeks (MCV: 61.5 ± 1.8 versus 57 ± 1.7 fL; P = 0.0156; Red blood count 7.4 ± 0.3 × 10(9)/L versus 8.6 ± 0.5 × 10(9)/L; P = 0.0156) and was reversible 90 days after SRL withdrawal. SRL in the culture medium of erythroid cultures led to fewer colonies in cultures from HC as well as from kidney transplant patients (without SRL: 34.2 ± 11.4 versus with SRL: 27.5 ± 9.9 BFU-E-derived colonies P = 0.03), regardless if the cultures were derived from recipients with normocytic or with microcytic erythrocytes. The presence of tacrolimus in the culture medium had no influence on the number and size of colonies.

CONCLUSION

mTOR inhibition induces microcytosis and polyglobulia, but not anaemia in healthy rats. This might be caused by growth inhibition of erythroid precursor cells.

Sirolimus and mycophenolate as combination prophylaxis in corneal transplant recipients at high rejection risk

PURPOSE

To examine efficacy and safety of dual sirolimus and mycophenolate mofetil systemic immunosuppression as allograft rejection prophylaxis after penetrating keratoplasty in patients at high rejection risk.

DESIGN

Prospective, interventional case series.

METHODS

settings: Single-center subspecialty clinic. patients: Six penetrating transplant recipients at high rejection risk and with no confounding additional cause for high risk of graft failure. All transplant recipient eyes had good visual potential. intervention: Treatment with oral mycophenolate mofetil in combination with sirolimus for 1 year, and sirolimus alone for 2 further years after keratoplasty at doses used in prophylaxis after cadaveric kidney transplantation. main outcomes measures: Interval to first rejection episode, transplant survival, and significant drug adverse effects. Minimum follow-up interval was 13 months after transplantation.

RESULTS

Rejection episodes occurred in 3 patients, one of which led to transplant failure. Of the 6 transplants, 5 remained clear at latest follow-up. Hepatotoxicity required discontinuation of mycophenolate in 1 patient, and both drugs were otherwise free of significant adverse effects.

CONCLUSIONS

Sirolimus and mycophenolate mofetil in combination are effective in extending corneal transplant survival in most but not all high rejection risk patients and generally are well tolerated. Results justify further evaluation of this regimen in a larger controlled study.

Elevated incidence of posttransplant erythrocytosis after simultaneous pancreas kidney transplantation

Posttransplant erythrocytosis (PTE) poses a potential risk of thrombosis in kidney transplantation. Clinical observation of our systemically drained simultaneous kidney pancreas transplant (S-SPK) patients showed a higher incidence of PTE and need for phlebotomies. To evaluate the incidence of PTE we analyzed hematocrit (Hct) levels and frequency of phlebotomies in 94 SPK as compared to 174 living donor (LD) recipients and 53 type-I diabetic with kidney transplant only. For study purposes we defined PTE as Hct >50% or the necessity for phlebotomies. Kaplan-Meier plots and Cox proportional hazard models were used to examine the association between the transplant type and PTE. We found an increased incidence of PTE in SPK compared to LD (p < 0.001). In the multivariate model, SPK had a 5-fold risk for the development of PTE (AHR 5.3, 95% CI 1.8, 15.9). The incidence of therapeutic phlebotomy was 13% among SPK patients and 4% in LD kidney recipients; 19 patients altogether. A total of 64 units were phlebotomized (48-SPK and 16-LD). Type I diabetic patients with a kidney transplant showed a 0% incidence of PTE. We observed a greater incidence of PTE and phlebotomies in S-SPK compared to LD with kidney only transplant recipients.

Cost-effectiveness of immunosuppressive regimens in renal transplant recipients in Germany: a model approach

BACKGROUND

The choice of immunosuppression regimen is of paramount importance for outcomes and cost of renal transplantation. We compared the cost-effectiveness of triple immunosuppressive regimens in Germany.

METHODS

A strong micro-simulation model was built comparing regimens based on cyclosporine, everolimus, sirolimus, and tacrolimus. Mean cost per patient, incremental cost per life year gained, and incremental cost per additional year with functioning graft were assessed from the perspective of the German statutory health insurance (SHI) after 2 and 10 years.

RESULTS

Over the 2-year period, the model predicted mean total costs per patient of 26,732, 29,352, 33,415, and 49,978 euro for sirolimus, cyclosporine, everolimus, and tacrolimus, respectively. Focusing on the cost per life year gained, the sirolimus-based regimen compared favorably with those based on everolimus and tacrolimus. The incremental cost-effectiveness ratio (ICER) of cyclosporine versus sirolimus is 524,000 euro per life year gained. Regarding the cost per year with functioning graft gained, sirolimus dominated cyclosporine and everolimus, while the ICER for tacrolimus compared to sirolimus amounts to 1,788,154 euro. Over the 10-year time frame, mean total costs per patient were 100,758, 108,300, 120,316, and 183,802 euro for sirolimus, cyclosporine, everolimus, and tacrolimus, respectively. With regard to life years gained, sirolimus dominated both cyclosporine and everolimus. The ICER of tacrolimus versus sirolimus was 1,766,894 euro. Considering the years with functioning graft gained, sirolimus dominated cyclosporine and everolimus, while the ICER for tacrolimus compared to sirolimus amounted to 1,339,419 euro.

CONCLUSIONS

Over both the 2-year and the 10-year time horizon, sirolimus-based immunosuppression represents a cost-effective option in renal transplantation in Germany.

Tacrolimus/sirolimus versus tacrolimus/mycophenolate in kidney transplantation: improved 3-year graft and patient survival in recent era

BACKGROUND

Registry analyses suggest that tacrolimus (TAC)/mycophenolate (MPA) immunosuppression is associated with superior kidney graft survival versus TAC/sirolimus (SRL). Large single-center experience can assist in clarifying these findings, by examining outcomes related to specific utilization practice.

METHODS

We retrospectively examined the outcomes of 518 consecutive first renal transplants at a single center treated with TAC/SRL (n=307) or TAC/MPA (n=211) with prednisone. Graft and patient survival, acute rejection, and 1-year glomerular filtration rate (GFR) were analyzed by era of transplant (2000-2002 vs. 2003-2006). Changes in TAC/SRL utilization between eras included elimination of the SRL loading dose and a reduction in TAC target trough concentrations.

RESULTS

Three-year graft survival with TAC/SRL was lower when first used (2000-2002) because of a higher incidence of patient death, primarily due to cardiovascular causes. Survival improved from 85.3% to 95.9% between 2000 to 2002 and 2003 to 2006 (P=0.001), with comparable graft and patient survival between TAC/SRL and TAC/MPA cohorts, confirmed following multivariable analysis controlling for donor and recipient factors. Rates of BK virus and acute rejection were comparable, but a higher incidence of hyperlipidemia, anemia, posttransplant diabetes, and a lower 1-year GFR (57.6 vs. 63.1 mL/min, P=0.008) was noted in the TAC/SRL cohort.

CONCLUSIONS

These data, as the largest long-term single-center report comparing TAC/SRL with TAC/MPA in kidney transplantation, demonstrate worse patient survival initially with TAC/SRL, with improved outcomes in a later era that were temporally associated with reduced TAC exposure. Differences in cardiovascular risk factors and 1-year GFR highlight the need for further investigation of the optimal utilization of SRL in kidney transplantation.

Posttransplant anemia: the role of sirolimus

Posttransplant anemia is a common problem that may hinder patients' quality of life. It occurs in 12 to 76% of patients, and is most common in the immediate posttransplant period. A variety of factors have been identified that increase the risk of posttransplant anemia, of which the level of renal function is most important. Sirolimus, a mammalian target of rapamycin inhibitor, has been implicated as playing a special role in posttransplant anemia. This review considers anemia associated with sirolimus, including its presentation, mechanisms, and management.