Sirolimus: a new promising immunosuppressive drug. Towards a rationale for its use in renal transplantation

A prognostic model of idiopathic pulmonary fibrosis constructed based on macrophage and mitochondria-related genes

BACKGROUND

Studies have shown that mitochondrial function and macrophages may play a role in the development of idiopathic pulmonary fibrosis (IPF). However, the understanding of the interactions and specific mechanisms between mitochondrial function and macrophages in pulmonary fibrosis is still very limited.

METHODS

To construct a prognostic model for IPF based on Macrophage- related genes (MaRGs) and Mitochondria-related genes (MitoRGs), differential analysis was performed to achieve differentially expressed genes (DEGs) between IPF and Control groups in the GSE28042 dataset. Then, MitoRGs, MaRGs and DEGs were overlapped to screen out the signature genes. The univariate Cox analysis and the least absolute shrinkage and selection operator (LASSO) algorithm were implemented to achieve key genes. Furthermore, the independent prognostic analysis was employed. The ingenuity pathway analysis (IPA) was employed to further understand the molecular mechanisms of key genes.Next, the immune infiltration analysis was implemented to identify differential immune cells between two risk subgroups.

RESULTS

There were 4791 DEGs between IPF and Control groups. Furthermore, 26 signature genes were achieved by the intersection processing. Three key genes including ALDH2, MCL1, and BCL2A1 were achieved, and the risk model based on the key genes was created. In addition, a nomogram for survival forecasting of IPF patients was created based on riskScore, Age, and Gender, and we found that key genes were associated with classical pathways including 'Apoptosis Signaling', 'PI3K/AKT Signaling', and so on. Next, two differential immune cells including Monocytes and CD8 T cells were identified between two risk subgroups. Moreover, we found that MIR29B2CHG and hsa-mir-1-3p could regulate the expression of ALDH2.

CONCLUSION

We achieved 3 key genes including ALDH2, MCL1,, and BCL2A1 associated with IPF, providing a new theoretical basis for clinical treatment of IPF.

The evolution and revolution of drug coated balloons in coronary angioplasty: An up-to-date review of literature data

European Society of Cardiology (ESC) guidelines gave class I A indication for use of DCB in in-stent restenosis. However, no indication exists for the usage of DCB in de novo lesions. Although the current generation DES offer excellent results, as we embark more complex lesions such as calcified lesion and chronic total occlusion, restenosis and stent thrombosis are higher and tend to increase within the years. There is increasing desire to leave nothing behind to abolish the risk of restenosis and stent thrombosis and hence the absorbable scaffolds were introduced, but with disappointing results. In addition, they take several years to be absorbed. Drug coated balloons offer an alternative to stents with no permanent implant of metal or polymer. They are already in use in in Europe and Asia and they have been approved for the first time in the United States for clinical trials specifically for restenotic lesions. There is emerging data in de novo lesions which have shown that DCB are noninferior and in some studies maybe even superior to current generation DES especially in small vessels. In this article, we provide a comprehensive review of the literature on this expanding technology focussing on the evidence in both re-stenotic and de novo lesions.

Proteins and their functionalization for finding therapeutic avenues in cancer: Current status and future prospective

Despite the remarkable advancement in the health care sector, cancer remains the second most fatal disease globally. The existing conventional cancer treatments primarily include chemotherapy, which has been associated with little to severe side effects, and radiotherapy, which is usually expensive. To overcome these problems, target-specific nanocarriers have been explored for delivering chemo drugs. However, recent reports on using a few proteins having anticancer activity and further use of them as drug carriers have generated tremendous attention for furthering the research towards cancer therapy. Biomolecules, especially proteins, have emerged as suitable alternatives in cancer treatment due to multiple favourable properties including biocompatibility, biodegradability, and structural flexibility for easy surface functionalization. Several in vitro and in vivo studies have reported that various proteins derived from animal, plant, and bacterial species, demonstrated strong cytotoxic and antiproliferative properties against malignant cells in native and their different structural conformations. Moreover, surface tunable properties of these proteins help to bind a range of anticancer drugs and target ligands, thus making them efficient delivery agents in cancer therapy. Here, we discuss various proteins obtained from common exogenous sources and how they transform into effective anticancer agents. We also comprehensively discuss the tumor-killing mechanisms of different dietary proteins such as bovine α-lactalbumin, hen egg-white lysozyme, and their conjugates. We also articulate how protein nanostructures can be used as carriers for delivering cancer drugs and theranostics, and strategies to be adopted for improving their in vivo delivery and targeting. We further discuss the FDA-approved protein-based anticancer formulations along with those in different phases of clinical trials.

Immunosuppressants Tacrolimus and Sirolimus revert the cardiac antifibrotic properties of p38-MAPK inhibition in 3D-multicellular human iPSC-heart organoids

Cardiac reactive fibrosis is a fibroblast-derived maladaptive process to tissue injury that exacerbates an uncontrolled deposition of large amounts of extracellular matrix (ECM) around cardiomyocytes and vascular cells, being recognized as a pathological entity of morbidity and mortality. Cardiac fibrosis is partially controlled through the sustained activation of TGF-β1 through IL-11 in fibroblasts. Yet, preclinical studies on fibrosis treatment require human physiological approaches due to the multicellular crosstalk between cells and tissues in the heart. Here, we leveraged an iPSC-derived multi-lineage human heart organoid (hHO) platform composed of different cardiac cell types to set the basis of a preclinical model for evaluating drug cardiotoxicity and assessing cardiac fibrosis phenotypes. We found that the inhibition of the p38-MAPK pathway significantly reduces COL1A1 depositions. Yet, concomitant treatment with organ-rejection immunosuppressant drugs Tacrolimus or Sirolimus reverts this effect, opening new questions on the clinical considerations of combined therapies in reducing fibrosis after organ transplantation.

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.

Role of Cytomegalovirus and Epstein-Barr virus in Patients with de Novo Colon Cancer after Renal Transplantation

Aims

The development of new effective immunosuppressive agents has provided long-term survival for transplant recipients, thereby increasing the risk of de novo malignancy in chronic immunocompromised hosts. Although de novo post-transplant lymphoproliferative diseases and skin cancer have been shown to have an increased incidence in long-term surviving solid organ transplant recipients, the association with colon cancer is controversial.

Patients and methods

Over a 12-year period, 20 patients (5%) out of 400 renal transplant recipients (treated at the University Hospitals of Udine and Ancona) developed 24 de novo tumors; 11 skin cancers and 13 non-skin cancers. Three patients developed de novo colon cancer. Immunosuppressive therapy was reduced immediately after diagnosis, and all patients were shifted from cyclosporine to rapamicine within 30 days. The tumor was surgically resected with curative intent in 2 cases, and 1 patient had only palliative surgery due to metastatic disease. The postoperative course was uneventful, and all patients maintained normal graft function.

Results

Two of 3 patients died of progression of the neoplasm, within a median time from the diagnosis of 12 months. We analyzed the possible correlations between de novo colon cancer and “serology (hepatitis C virus-hepatitis B virus, HCV-HBV) status'’ infections, cytomegalovirus and Epstein-Barr virus reactivation, episodes of rejection, and blood transfusions.

Conclusions

Differently from other de novo skin and non-skin tumors, our cases developed cytomegalovirus and Epstein-Barr virus reactivation within 3 months of transplantation. Therefore, we suggest a closer follow-up for de novo colon cancer in renal transplants with early cytomegalovirus and Epstein-Barr virus reactivation in order to avoid a delay in diagnosis.

Preparation and Preclinical Evaluation of Inhalable Particles Containing Rapamycin and Anti-Tuberculosis Agents for Induction of Autophagy

PURPOSE

Mycobacterium tuberculosis (Mtb) inhibits host defense mechanisms, including autophagy. We investigated particles containing rapamycin (RAP) alone or in combination with isoniazid (INH) and rifabutin (RFB) for: targeting lung macrophages on inhalation; inducing autophagy; and killing macrophage-resident Mtb and/or augmenting anti-tuberculosis (TB) drugs.

METHODS

PLGA and drugs were spray-dried. Pharmacokinetics, partial biodistribution (LC-MS/MS) and efficacy (colony forming units, qPCR, acid fast staining, histopathology) in mice following dry powder inhalation were evaluated.

RESULTS

Aerodynamic diameters of formulations were 0.7-4.7 μm. Inhaled particles reached deep lungs and were phagocytosed by alveolar macrophages, yielding AUC0-48 of 102 compared to 0.1 μg/ml × h obtained with equivalent intravenous dose. RAP particles induced more autophagy in Mtb-infected macrophages than solutions. Inhaled particles containing RAP alone in daily, alternate-day and weekly dosing regimens reduced bacterial burden in lungs and spleens, inducing autophagy and phagosome-lysosome fusion. Inhalation of particles containing RAP with INH and RFB cleared the lungs and spleens of culturable bacteria.

CONCLUSIONS

Targeting a potent autophagy-inducing agent to airway and lung macrophages alone is feasible, but not sufficient to eliminate Mtb. Combination of macrophage-targeted inhaled RAP with classical anti-TB drugs contributes to restoring tissue architecture and killing Mtb.

Kinetics of rapamycin production by Streptomyces hygroscopicus MTCC 4003

Research work was carried out to describe the kinetics of cell growth, substrate consumption and product formation in batch fermentation of rapamycin using shake flask as well as laboratory-scale fermentor. Fructose was used as the sole carbon source in the fermentation media. Optimization of fermentation parameters and reliable mathematical models were used for the maximum production of rapamycin from Streptomyces hygroscopicus MTCC 4003. The experimental data for microbial production of rapamycin fitted well with the proposed mathematical models. Kinetic parameters were evaluated using best fit unstructured models, viz. Andrew's model, Monod model, Yano model, Aiba model. Andrew's model showed a comparatively better R² value (0.9849) among all tested models. The values of maximum specific growth rate (μ_max), saturation constant (K_S), inhibition constant (K_i), and growth yield coefficient (Y_X/S) were found to be 0.008 (h^-1), 2.835 (g/L), 0.0738 (g/L), and 0.1708 (g g^-1), respectively. The optimum production of rapamycin was obtained at 300 rpm agitation and 1 vvm aeration rate in the fermentor. The final production of rapamycin in shake flask was 539 mg/L. Rapamycin titer found in bioreactor was 1,316 mg/L which is 52 % higher than the latest maximum value reported in the literature.

Immunostimulatory activity of lifespan-extending agents

During the past two decades, several interventions have been shown to increase the healthy lifespan of model organisms as evolutionarily distant from each other as yeast, worms, flies and mammals. These anti-aging maneuvers include (but are not limited to) cycles of caloric restriction, physical exercise as well as the administration of multiple, chemically unrelated agents, such as resveratrol, spermidine and various rapamycin-like compounds collectively known as rapalogs. Most, if not all, lifespan-extending agents promote macroautophagy (hereafter referred to as autophagy), an evolutionarily old mechanism that contributes to the maintenance of intracellular homeostasis and plays a critical role in the adaptive response of cells to stress. In line with this notion, the activation of autophagy appears to mediate significant anti-ageing effects in several organisms, including mice. Here, we focus on rapalogs to discuss the possibility that part of the beneficial activity of lifespan-extending agents stems from their ability to exert immunostimulatory effects. Accumulating evidence indicates indeed that the immune system can recognize and eliminate not only cells that are prone to undergo malignant transformation, but also senescent cells, thus playing a significant role in the control of organismal aging. In addition, it has recently become clear that rapamycin and other rapalogs, which for a long time have been viewed (and used in the clinic) as pure immunosuppressants, can mediate robust immunostimulatory functions, at least in some circumstances.

Spatial and cellular characterization of mTORC1 activation after spinal cord injury reveals biphasic increase mainly attributed to microglia/macrophages

Mechanistic target of rapamycin complex 1 (mTORC1) is an intracellular kinase complex that regulates energy homeostasis and transcription. Modulation of mTORC1 has proven beneficial in experimental spinal cord injury, making this molecular target a candidate for therapeutic intervention in spinal cord injury. However, both inactivation and activation of mTORC1 have been reported beneficial for recovery. To obtain a more complete picture of mTORC1 activity, we aimed to characterize the spatiotemporal activation pattern of mTORC1 and identify activation in particular cell types after contusion spinal cord injury in rats. To be able to provide a spatial characterization of mTORC1 activation, we monitored activation of downstream target S6. We found robust mTORC1 activation both at the site of injury and in spinal segments rostral and caudal to the injury. There was constitutive mTORC1 activation in neurons that was biphasically reduced caudally after injury. We found biphasic mTORC1 activation in glial cells, primarily activated microglia/macrophages. Furthermore, we found mTORC1 activation in proliferating cells, suggesting this may be a function affected by mTORC1 modulation. Our results reveal potential windows of opportunity for therapeutic interference with mTORC1 signaling and immune cells as targets for inhibition of mTORC1 in spinal cord injury.

Synergism between mTOR pathway and ultraviolet radiation in the pathogenesis of squamous cell carcinoma and its implication for solid-organ transplant recipients

Nonmelanoma skin cancers (NMSCs) are the most common malignancies in the United States in immunocompetent patients. Among the solid-organ transplant recipients, NMSCs represent a significant disease burden, and they tend to be multiple and more aggressive. While the precise mechanisms responsible for the higher risk of developing cutaneous squamous cell carcinomas (SCCs) have not been completely elucidated, ultraviolet (UV) light has been established to be critical in initiation and promotion of tumor development. More recently, significant emphasis has been placed on the role of the mammalian target of rapamycin (mTOR) pathway in SCC pathogenesis. Furthermore, some studies have demonstrated the ability of mTOR inhibitors to decrease the incidence of new SCCs in the immunosuppressed transplanted patient population. In this review, we will highlight and examine the most recent available data on the role of UV radiation and its interaction with mTOR pathway signaling in SCC pathogenesis.

Correction of glycogen storage disease type III with rapamycin in a canine model

Recently, we reported that progression of liver fibrosis and skeletal myopathy caused by extensive accumulation of cytoplasmic glycogen at advanced age is the major feature of a canine model of glycogen storage disease (GSD) IIIa. Here, we aim to investigate whether rapamycin, a specific inhibitor of mTOR, is an effective therapy for GSD III. Our data show that rapamycin significantly reduced glycogen content in primary muscle cells from human patients with GSD IIIa by suppressing the expression of glycogen synthase and glucose transporter 1. To test the treatment efficacy in vivo, rapamycin was daily administered to GSD IIIa dogs starting from age 2 (early-treatment group) or 8 months (late-treatment group), and liver and skeletal muscle biopsies were performed at age 12 and 16 months. In both treatment groups, muscle glycogen accumulation was not affected at age 12 months but significantly inhibited at 16 months. Liver glycogen content was reduced in the early-treatment group but not in the late-treatment group at age 12 months. Both treatments effectively reduced liver fibrosis at age 16 months, consistent with markedly inhibited transition of hepatic stellate cells into myofibroblasts, the central event in the process of liver fibrosis. Our results suggest a potential useful therapy for GSD III.

KEY MESSAGES

Rapamycin inhibited glycogen accumulation in GSD IIIa patient muscle cells. Rapamycin reduced muscle glycogen content in GSD IIIa dogs at advanced age. Rapamycin effectively prevented progression of liver fibrosis in GSD IIIa dogs. Our results suggest rapamycin as potential useful therapy for patients with GSD III.

Antibiotics acting as neuroprotectants via mechanisms independent of their anti-infective activities

This review considers available evidence that some antibiotics have ancillary neuroprotective effects. Notably, β-lactam antibiotics are believed to increase the expression of glutamate transporter GLT1, potentially relieving the neurological excitotoxicity that characterizes disorders like amyotrophic lateral sclerosis. Minocycline has shown promise in reducing the severity of a number of neurological diseases, including multiple sclerosis, most likely by reducing apoptosis and the expression of inflammatory mediators in the brain. Rapamycin inhibits the activity of a serine/threonine protein kinase that has a role in the pathogenesis of numerous neurologic diseases. Herein we examine the unique neuroprotective aspects of these drugs originally developed as anti-infective agents.

Cost Utility of Sirolimus versus Tacrolimus for the Primary Prevention of Graft Rejection in Renal Transplant Recipients in Mexico

OBJECTIVE

Therapies for end-stage renal disease improve quality of life, and survival. In Mexico, clinicians often must choose between different therapies without the availability of comparative outcomes evaluation. The present study evaluates the comparative cost-utility of sirolimus (SIR) versus tacrolimus (TAC) for the primary prevention of graft rejection in renal transplant recipients in Mexico.

METHODS

We used modeling techniques to estimate the cost-effectiveness of SIR versus TAC to prevent graft rejection in patients with end-stage renal disease in the Mexican setting. The model estimates the cost of quality-adjusted life-year (QALY) per patient. We applied a 20-year horizon (1-year Markov cycles). Cost-effectiveness was expressed in terms of cost per QALY. All costs are presented in 2011 US dollars. Probabilistic sensitivity analyses were conducted.

RESULTS

The total cost for the SIR treatment arm over the 20-year duration of the model is estimated to be $136,778. This compares with $142,624 for the TAC treatment arm, resulting in an incremental cost of SIR compared with that of TAC of-$5,846. Over 20 years, SIR was estimated to have 8.18 QALYs compared with 7.33 QALYs for TAC. The resulting incremental utility of SIR compared with that of TAC is 0.84 QALY gained. SIR is estimated to be both less costly and more effective than TAC, indicating that it is the dominant strategy. Notably, results suggest that SIR has a 78% probability of being dominant over the TAC strategy and a 100% probability of having an incremental cost-effectiveness ratio at or below $10,064 (1 GDP) per QALY.

CONCLUSIONS

These analyses suggest that in the Mexican setting, the use of SIR in place of TAC for the prevention of graft rejection in this population is likely to be cost saving.

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.

Application of bioactivity database of Chinese herbal medicine on the therapeutic prediction, drug development, and safety evaluation

AIM OF THE STUDY

Chinese herbal medicine has been used for the treatments of various diseases for years. However, it is often difficult to analyze their biological activities and molecule mechanisms because of their complex nature. In this study, we applied DNA microarray to analyze the biological events induced by herbal formulae, predict the therapeutic potentials of formulae, and evaluate the safety of formulae.

MATERIALS AND METHODS

Mice were administrated orally with 15 formulae for 7 consecutive days, and the gene expression profiles in liver or kidney were further analyzed by transcriptomic tools.

RESULTS

Our data showed that most formulae altered the metabolic pathways, such as glutathione metabolism and oxidative phosphorylation, and regulatory pathways, such as antigen processing and presentation and insulin-like growth factor signaling pathway. By comparing the gene expression signatures of formulae with those of disease states or drugs, we found that mice responsive to formula treatments might be related to disease states, especially metabolic and cardiovascular diseases, and drugs, which exhibit anti-cancer, anti-inflammatory, and anti-oxidative effects. Moreover, most formulae altered the expression levels of cytochrome p450, glutathione S-transferase, and UDP glycosyltransferase genes, suggesting that caution should be paid to possible drug interaction of these formulae. Furthermore, the similarities of gene expression profiles between formulae and toxic chemicals were low in kidney, suggesting that these formulae might not induce nephrotoxicities in mice.

CONCLUSIONS

This report applied transcriptomic tools as a novel platform of translational medicine for Chinese herbal medicine. This platform will not only for understanding the therapeutic mechanisms involving herbal formulae and gene interactions, but also for the new theories in drug discovery.

Stem cell marker upregulation in normal cutaneous vessels following pulsed-dye laser exposure and its abrogation by concurrent rapamycin administration: implications for treatment of port-wine stain birthmarks

Port-wine stains (PWS) represent a group of vascular malformations that are usually accompanied by psychological distress for affected patients, often reflected in high treatment demand. Although the pulsed-dye laser (PDL) was established as standard therapy for PWS more than a decade ago, therapeutic outcome may be unsatisfactory. One of the main drawbacks to successful PDL therapy is PWS revascularization shortly after laser exposure. Therefore, inhibition of revascularization should improve therapeutic outcome of PDL therapy. In this study, we first evaluated the effects of various light energies on normal cutaneous vessels over a period of 14 days, particularly the proliferation and stem cell marker expression of dermal endothelial cells, which were found to be highest 8 days following laser exposure. We found that PDL exposure induced dose-dependent damage of dermal vessels up to energy densities of 6 J/cm(2), above which no increase in PDL-induced effects were observed with the energies employed in this study. In dermal endothelial cells of PDL-exposed skin, we found strong expression of the proliferation marker Ki-67 as well as the stem cell marker nestin but not other stem cell markers such as CD133 and CD166. The influence of rapamycin (RPM), used as an adjuvant to PDL exposure, was also investigated. RPM administration reduced Ki-67 and nestin expression in dermal endothelial cells and increased PDL-induced destruction of dermal vessels, indicating that the use of RPM after PDL exposure may be an interesting new approach for prolonging and improving PWS laser therapeutic outcome.

Switch to a sirolimus-based immunosuppression in long-term renal transplant recipients: reduced rate of (pre-)malignancies and nonmelanoma skin cancer in a prospective, randomized, assessor-blinded, controlled clinical trial

Renal transplant recipients (RTR) have a 50-200-fold higher risk for nonmelanoma-skin cancer (NMSC) causing high rates of morbidity and sometimes mortality. Cohort-studies gave evidence that a sirolimus-based immunosuppression may inhibit skin tumor growth. This single-center, prospective, assessor-blinded, randomized trial investigated if switching to sirolimus treatment inhibits the progression of premalignancies and moreover how many new NMSC occur compared to continuation of the original immunosuppressive therapy. Forty-four RTR (mean age 59.9 years, mean duration of immunosuppression 229.5 months) with skin lesions were randomized to sirolimus or continuation of their original immunosuppression. Blinded dermatological assessment at month 6 and 12 by the same dermatologist evaluated the clinical change compared to baseline. Biopsy was performed in suspected malignancy. Already the 6-month-assessment showed significant superiority of sirolimus-therapy: a stop of progression, even regression of preexisting premalignancies (p < 0.0005). This effect was increased at month 12 (p < 0.0001). Nine patients developed histologically confirmed NMSC: one in the sirolimus group, eight in the control group, p = 0.0176. Sirolimus-based immunosuppression in RTR, even when established many years after transplantation, can delay the development of premalignancies, induce regression of preexisting lesions and decelerate the incidence of new NMSC.

Preferential increase in memory and regulatory subsets during T-lymphocyte immune reconstitution after Thymoglobulin induction therapy with maintenance sirolimus vs cyclosporine

BACKGROUND

Sirolimus maintenance therapy with Thymoglobulin induction is a promising regimen that may preserve renal function. Data are lacking, however, about the immunologic effects of combined Thymoglobulin-sirolimus.

METHODS

In a 12-month, prospective, randomised, open-label, single-centre pilot study, de novo deceased-donor kidney transplant patients were randomised to receive cyclosporine or sirolimus, with Thymoglobulin induction, mycophenolate mofetil and corticosteroids. Flow cytometry analysis of peripheral blood was used to evaluate immune reconstitution.

RESULTS

Nineteen patients were recruited (sirolimus 9, cyclosporine 10). Reconstitution of the CD4(+) T-lymphocyte subset was significantly lower with sirolimus versus cyclosporine over year 1, but CD8(+) reconstitution did not differ significantly between groups. The proportion of naïve CD4(+) T-lymphocytes showed an initial decrease with sirolimus versus cyclosporine. Naïve CD8(+) T-lymphocytes increased versus baseline in the cyclosporine cohort at months 1 and 3, but remained unchanged with sirolimus. Memory CD4(+) T-lymphocytes occurred more frequently in sirolimus- versus cyclosporine-treated patients during year 1. The proportion of memory CD8(+) T-lymphocytes decreased at months 1 and 3 compared to baseline in the CsA arm, but did not change in the sirolimus cohort. By month 12, the proportion of both naïve and memory CD4(+) and CD8(+) T-lymphocytes had become similar with sirolimus or cyclosporine. There were fewer naïve B-lymphocytes in the sirolimus cohort and more CD19(-)IgD(+/-)CD27(+) memory B-lymphocytes.

CONCLUSIONS

In this small population, homeostatic reconstitution after Thymoglobulin induction showed disproportionately high recovery of memory T-lymphocyte subsets during sirolimus therapy, which may explain the higher rejection rate seen with sirolimus versus cyclosporine following kidney transplantation.

Spontaneous pyopneumothorax in patients treated with mTOR inhibitors for subpleural pulmonary metastases

Spontaneous pyopneumothorax is a very rare occurrence, even in cancer treated patients. Here we present two consecutive cases of spontaneous pyopneumothorax that occurred early after initiation of mTOR inhibitors for the treatment of renal cell carcinoma with subpleural pulmonary metastasis. In these two cases, necrosis and excavation of lung metastasis were observed, suggesting their involvement in the pathogenic mechanism of pyopneumothorax. This report extends the available experience of the pulmonary side effects of these novel targeted therapies.

Quantification of sirolimus and everolimus by immunoassay techniques: test specificity and cross-reactivity evaluation

The possible cross-reactivity of immunoassays with structurally-related drugs was investigated. Innofluor Certican (FPIA) calibrators were measured by using IMx Sirolimus assay (MEIA) and MEIA Sirolimus calibrators were analysed by using FPIA Certican assay. Drug concentrations were measured in 95 and 100 samples from renal transplanted patients (RTP) on sirolimus or everolimus treatment by using immunoassays and LC/ESI-MSMS. A high cross-reactivity was found both for MEIA and FPIA. High correlation degrees, confirmed by the Bland-Altman and the Eksborg tests, were found between drug concentrations measured in real samples by both immunoassays (r = 0.909 and r = 0.970, respectively). LC/ESI-MSMS analysis of samples containing sirolimus showed no positivity for everolimus. Similarly, samples from patients on treatment with everolimus resulted negative as far as regards sirolimus. MEIA and FPIA could be considered mutually reliable and accurate alternatives for the specific-drug immunoassay. It should be noticed that in patients switching from one drug to the other unreal overestimation of the blood levels of the current administered immunosuppressant can occur.

Prevention of murine lupus disease in (NZBxNZW)F1 mice by sirolimus treatment

Sirolimus is a new immunosuppressive drug used to avoid allograft rejection. The immunosuppressive effect of sirolimus is due to inhibition of the mammalian target of rapamycin, necessary for the proliferation and clonal expansion of activated T-cells. Because T-cells play a central role in the pathogenesis of autoimmune disease developed in (NZBxNZW)F1 mice, we evaluated the therapeutic use of sirolimus in such mice. (NZBxNZW)F1 female mice received 1mg/kg/day of sirolimus from 12 to 37 weeks of age. The development of autoimmune disease was evaluated by measuring the serum levels of auto-antibodies (autoAbs) and their immunoglobulin isotypes, prevalence of glomerulonephritis and mortality rates. Sirolimus directly inhibited production of autoAbs, glomerular deposits of immunoglobulins and development of proteinuria; also the survival of these mice was prolonged. Our results demonstrate the beneficial effects of sirolimus in preventing the development of lupus disease in (NZBxNZW)F1 female mice.

Study of Anemia After Late Introduction of Everolimus in the Immunosuppressive Treatment of Renal Transplant Patients

INTRODUCTION

mTOR inhibitors (imTOR) are immunosuppressive drugs that have a concentration-related effects on hematopoiesis, potentially resulting in anemia. The reason is uncertain, but a pathogenic link between sirolimus-induced anemia and the appearance of an inflammatory state was recently suggested. Because inflammation-related anemia is characterized by a functional iron deficiency, we studied whether everolimus influenced iron homeostasis.

METHODS

We studied iron homeostasis in 43 patients after late introduction of everolimus into the immunosuppressive treatment. Thirty-seven patients (86%) were receiving mycophenolate. Hemoglobin concentration, red blood cell count, mean corpuscular volume, serum iron, ferritin, C-reactive protein levels, and transferrin saturation were evaluated 3 months before and 1, 3, and 6 months after the switch.

RESULTS

The percentage of anemic patients preconversion was 18.6% and it was 34.9% at 3 months and 18.6% at 6 months. We did not observe a significant reduction in hemoglobin, but there was increased red blood cell count after everolimus introduction, with a significant reduction in mean corpuscular volume. Serum iron and transferrin saturation levels were also markedly reduced after the switch, while ferritin serum concentrations remained stable. An improvement in renal function was observed.

CONCLUSIONS

The anemia caused by everolimus--microcytosis, low serum iron, despite high ferritinemia, and elevated C-reactive protein levels--was consistent with the anemia of a chronic inflammatory state. This alteration occurred within the first months postconversion and disappeared at 6 months. The combination of mycophenolate and everolimus seemed to be useful without significant secondary effects.

Pulmonary alveolar proteinosis ? a rare pulmonary toxicity of sirolimus

The aim of our paper is to describe an unusual pulmonary toxicity of sirolimus (SRL) in a kidney transplant recipient. We present a 34-year-old woman with a second renal transplantation, complicated with steroid-resistant acute rejection and chronic allograft dysfunction. Two years after initiating SRL, she presented complaints of progressive dyspnoea, nonproductive cough, chest pain and low-grade fever of 1 month duration. She had chronic allograft nephropathy and slight elevation of lactic dehydrogenase levels. After exclusion of common reasons of this condition, a computed tomography (CT) of the thorax and bronchoscopy was performed, revealing ground-glass opacification with polygonal shapes on CT and an opaque appearance with numerous macrophages on bronchoalveolar lavage. The alveolar macrophages stained positive by Periodic acid-Schiff. Diagnosis of pulmonary alveolar proteinosis (PAP) was made and drug-induced toxicity was suspected. SRL was withdrawn with marked improvement in the patients' clinical and radiological status. PAP resolved within 3 months without further therapy. PAP is a very rare complication of SRL therapy with only a few cases described. Withdrawal of SRL with conversion to another immunosuppressant seems to be an appropriate procedure in this condition.

De novo gastrointestinal tumours after renal transplantation: role of CMV and EBV viruses

The development of new and more effective immunosuppressive agents has provided long-term survival for transplant recipients, thereby increasing the risk of de novo malignancy in chronic immunocompromised hosts. While de novo post-transplant lymphoproliferative diseases and skin cancer has been shown to have an increased incidence in long-term surviving solid organ transplant recipients, the association with gastrointestinal (GI) cancer is controversial. Over 12 yr, 20 patients (5%) out of 395 renal transplant recipients developed 23 de novo tumours; 11 skin cancer and 12 non-skin cancer. Four patients (1%) developed de novo tumours of the GI tract (three colon, and one gastric cancer). Immediately after tumour's diagnosis, immunosuppressive therapy was reduced; all patients were shifted from cyclosporine to Rapamicine within 30 d. The tumour was surgically resected with curative intent in three cases, while one patient had only palliative surgery because of metastatic disease. The post-operative courses was uneventful. All patients maintained normal graft function. However, three out of four patients (75%) died of progression of the neoplasm, within a median time from the diagnosis of 12 months. Further, we investigated a possible correlations between de novo GI cancer and HCV, HBV status, infections, cytomegalovirus (CMV) and Epstein-Barr virus (EBV) reactivation, episodes of rejection, and blood transfusions. All cases with GI de novo cancers reported in this paper developed CMV and EBV reactivation within three months after transplantation. Thereafter we suggest a closer follow-up for de novo GI cancer in renal transplants with early CMV and EBV reactivation in order to avoid delayed diagnosis.

Sirolimus Interferes with Iron Homeostasis in Renal Transplant Recipients

BACKGROUND

Sirolimus is an immunosuppressive drug whose use is frequently associated with anemia. A pathogenic link between sirolimus-induced anemia and the appearance of an inflammatory state was recently suggested. Because inflammation-related anemia is characterized by a functional iron deficiency, we investigated whether sirolimus may influence iron homeostasis and serum levels of hepcidin, a key mediator of inflammation-related anemia.

METHODS

To this purpose, 42 consecutive transplanted patients with biopsy-proven chronic allograft nephropathy were randomized (2:1 ratio) to receive either a 40% cyclosporine reduction (group A, 14 patients) or immediate cyclosporine withdrawal and sirolimus introduction (group B, 28 patients). Hemoglobin levels and iron status were evaluated 6 months before and after randomization.

RESULTS

The two groups had similar hemoglobin levels and iron status at baseline. We did not observe any significant change in hemoglobin and iron status in group A patients after randomization. On the contrary, we observed a significant reduction of hemoglobin without any change of red blood cell count after sirolimus introduction, with a significant reduction of mean corpuscular volume and mean corpuscular hemoglobin. Serum iron and transferrin saturation (TSAT) levels were markedly reduced after the switch, while ferritin serum concentrations remained stable. Although sirolimus-induced anemia was recently suggested to resemble inflammation-related anemia, hepcidin serum levels were similar in the two groups after randomization. None of group A and eight of group B patients presented a TSAT <20 and were given iron supplementation after randomization, in all of them oral iron therapy did not influence either hemoglobin or serum iron levels.

CONCLUSION

We demonstrated that sirolimus-induced anemia is independent of the drug antiproliferative effect and does not present the features of inflammation-related anemia. This event may be due to the direct influence of sirolimus on iron homeostasis.

Renal function in renal or liver transplant recipients after conversion from a calcineurin inhibitor to sirolimus

Two Six-month pilot studies were conducted in renal (n = 17) or liver (n = 15) transplant recipients to evaluate renal function after conversion from calcineurin inhibitor (CI)- to sirolimus (SRL)-based immunosuppression. After an SRL loading dose, doses were individualized to achieve whole blood trough levels of 10-22 ng/mL. Overall, serum creatinine did not change from baseline to six months post-conversion but an improvement from 219.9 to 201.4 micromol/L at three months was noted in renal transplant recipients (p < 0.05). Another finding was a numerical increase in the mean glomerular filtration rate (GFR) from 26.8 to 33.2 mL/min/1.73 m(2) at six months among liver transplant recipients (NS). All patients survived and all grafts were functioning at the end of the study. In conclusion, renal function remained stable, with a tendency towards improvement, after abrupt conversion from CI- to SRL-based therapy in renal or liver transplant recipients with moderate renal insufficiency.

Characterisation of the lung toxicity of the cell cycle inhibitor temsirolimus

The aims of this study were reviewing our experience regarding the pulmonary toxicity of the mammalian target of rapamycin (mTOR) inhibitor temsirolimus, discussing potential pathogenic mechanisms and proposing management strategies. Medical records and radiological reports of 22 patients treated with weekly doses of temsirolimus 25 mg were reviewed. Eight (36%) out of 22 patients developed pulmonary abnormalities compatible with drug-induced pneumonitis. Half were asymptomatic and in those with symptoms, dyspnea and dry cough were the most common. Radiologically two different patterns, ground glass opacities and lung parenchymal consolidation, were described. The management of this toxicity was variable, ranging from no intervention to discontinuation of the drug. In our experience temsirolimus may cause drug-induced pneumonitis at a higher incidence than that previously reported. The presentation and its severity are variable. The risk of developing this toxicity may be increased among subjects with abnormal pre-treatment pulmonary functions or history of lung disease.

Sirolimus-Induced Remission of Posttransplantation Lymphoproliferative Disorder

Posttransplantation lymphoproliferative disorder (PTLD) is one of the most serious complications of solid-organ transplantation. It potentially is treatable in most cases, but current methods involve withdrawal or reduction of immunosuppression and the consequent risk for graft rejection. Sirolimus was shown in vivo and in vitro to limit proliferation of a number of malignant cell lines, including those of PTLD-derived cells. We present a case of disseminated PTLD in a patient with a renal transplant that resolved completely with conversion of immunosuppression to sirolimus. Graft function was maintained and improved with treatment. This offers a novel means of treating these patients and minimizing transplant loss.

Evaluation of the cost effectiveness of sirolimus versus tacrolimus for immunosuppression following renal transplantation in the UK

INTRODUCTION

Immunosuppressive therapy is required to prevent graft rejection. Calcineurin inhibitors such as tacrolimus are paradoxically toxic to the kidney, whereas sirolimus (rapamycin; Rapamune) is not generally associated with the nephrotoxicity of CNIs. The purpose of this study was to evaluate the relative cost utility of sirolimus versus tacrolimus for the primary prevention of graft rejection in renal transplant recipients in the UK.

METHODS

A stochastic simulation model was constructed using clinical trial and observational data comparing the two treatments. Time duration was up to 20 years. Costs were from a UK NHS perspective, valued at 2003 prices and discounted at 6%. Benefits were discounted at 1.5%. Simulated events included patient and graft survival, haemodialysis, peritoneal dialysis, re-transplants and acute rejection. Costs were summed for events and various maintenance therapies. Utility was differentially accredited depending upon survival and using the alternative renal replacement therapies. Outcome was predicted using post-transplant creatinine levels up to 3 years. Extensive statistical economic and sensitivity analyses were undertaken.

RESULTS

Over the 10-year horizon, sirolimus gained 0.72 years (discounted) of functioning graft over tacrolimus, resulting in an incremental cost per year of functioning graft that was dominant. Over a 20-year time horizon, the cost effectiveness of sirolimus over tacrolimus further improved with an average discounted gain in years of a functioning graft of 1.8 years, resulting in an incremental cost-utility ratio that was also dominant. The number of haemodialysis events was 48,243 for sirolimus recipients versus 127,829 for those receiving tacrolimus and peritoneal dialysis events 40,872 versus 105,249, respectively. Similar values were obtained when real-life observational data on tacrolimus use in Cardiff, Wales were entered into the model. Using data from Cardiff, sirolimus remained dominant over tacrolimus under all scenarios.

CONCLUSION

Our study suggests that sirolimus may be more cost effective than tacrolimus for the primary prevention of graft rejection in renal transplant recipients in the UK. Sirolimus was economically 'dominant' under almost all scenarios investigated. This finding was robust using statistical economic analysis and univariate sensitivity analysis.

Evaluation of the cost-effectiveness of Sirolimus versus cyclosporin for immunosuppression after renal transplantation in the United Kingdom

OBJECTIVE

The purpose of this study was to evaluate the cost-effectiveness of sirolimus compared with cyclosporin for the postsurgical management of renal transplant recipients, from the perspective of the UK National Health Service and the Personal Social Service.

METHODS

A discrete event stochastic simulation model was developed to evaluate both cost-effectiveness and cost utility over 10 and 20 years after transplant using historical data on 937 renal transplant recipients from the University Hospital of Wales in Cardiff, United Kingdom. The simulation was designed to forecast the incidence of acute rejection events, graft failure, retransplant, frequency of hemodialysis (HD) and peritoneal dialysis (PD), and death. Cox proportional hazard models were derived from historical transplant data, in which 1-, 2-, and 3-year post-transplant serum creatinine levels were used as the key drivers for predicting graft success and survival. Costs were reported as year-2003 UK pounds sterling (1 UK pound = US $1.76). Probabilistic sensitivity analysis was conducted and results reported with particular attention to 2 threshold values, 30,000/QALY and 20,000/QALY RESULTS: Over a 10-year time horizon, treatment with sirolimus was projected to produce a gain of 0.60 discounted year of functioning graft with a cost savings of 276 UK pounds per patient. Over a 20-year time horizon these benefits increased to 1.59 discounted years of functioning graft and a cost savings of 7405 UK pounds per patient. Using sensitivity analysis of the 10-year model, the only factors found to cause the probability of exceeding a 30,000 ceiling to be >5% were the proportion of subjects maintaining continuous graft function and the use of low-dose cyclosporin. With the 20-year model, sirolimus maintained cost-effectiveness across most scenarios in sensitivity analysis.

CONCLUSIONS

In this model analysis, sirolimus was cost-effective compared with cyclosporin for 10 to 20 years after renal transplantation in the United Kingdom, from the perspective of the UK National Health Service and Personal Social Service.

Sirolimus as Primary Immunosuppression Agent in Kidney Transplant Recipients: Akdeniz University Experience

OBJECTIVES

Recently usage of sirolimus as the primary immunosuppressant is widening among kidney transplant recipients. We reviewed the clinical follow-up of patients transplanted at our center using sirolimus protocols.

METHODS

Sirolimus including primary immunosuppressive treatment protocols were begun in February 2002. Among the 21 patients (15 men, six women) who received sirolimus, six patients were prescribed sirolimus + prednisolone; seven, sirolimus + mycophenolate mofetil + prednisolone; and eight, sirolimus + cyclosporine + prednisolone. The mean age of the patients was 32.9 +/- 7.3 years and the mean posttransplantation follow-up, 13.2 +/- 4.5 months.

RESULTS

Three patients experienced acute rejection episodes, which were treated successfully with steroids. None of the patients had either hematologic or wound healing problems. Lymphoceles developed in eight patients. Serum creatinine level was 1.4 +/- 0.5 mg/dL at 12 months. There was a serious increase in serum cholesterol and triglyceride levels starting from the first month posttransplant (total cholesterol levels pretransplant and at 1 month, respectively: 159.3 +/- 29.5 and 255.7 +/- 52.3 mg/dL, P = .0001; triglycerides pretransplant and at 1 month, respectively: 146.9 +/- 89.5 and 215.1 +/- 102.5 mg/dL, P = .001). Despite routine antihyperlipemic treatment those high levels were maintained for 12 months.

CONCLUSIONS

We achieved 100% graft and patient survival rates for 1 year among patients who were using sirolimus. But the most important role in defining the morbidity and mortality in this group of patients is cardiovascular events; for this reason the abnormalities in the lipid profile must be taken seriously.

Successful simultaneous islet-kidney transplantation using a steroid-free immunosuppression: two-year follow-up

We report on the feasibility of a glucocorticoid-free immunosuppression (sirolimus, low-dose tacrolimus, and daclizumab) in simultaneous islet-kidney transplantation in nine patients with type 1 diabetes. There was one renal primary nonfunction. Renal function (n = 8) as assessed by creatinine and creatinine clearance over time was 103 +/- 6 micromol/L and 64 +/- 6 mL/min/1.73 m(2), respectively. Five out of six patients with >or= 2 islet transplantations became insulin independent. The mean HbA(1c) during the follow-up period for all patients after transplantation is 6.2 +/- 0.9% as compared with 8.7 +/- 1.9% prior to transplant. These results in patients with a median follow-up of 2.3 years suggest that kidney transplantation under a glucocorticoid-free immunosuppression is feasible, and that the rate of insulin independence of 80% can be achieved not only in patients with no or minimal diabetes complications, but also in patients with more advanced late complications and in conjunction with kidney transplantation.

Therapeutic drug monitoring of immunosuppressive drugs in kidney transplantation

PURPOSE OF REVIEW

Drug monitoring has become an accepted adjunct to optimizing therapy with immunosuppressive drugs. This review assesses publications that relate to the analytical techniques used to measure cyclosporin, tacrolimus, mycophenolic acid, sirolimus and everolimus, as well as the clinical data obtained for these drugs. For all of these drugs there has been a substantial and continuing investment in assessing the clinical value of drug monitoring.

RECENT FINDINGS

Fundamental controversies still persist regarding which time point to use for monitoring. The most significant single development has been the move towards using a timed blood sample 2 h after drug administration (C2) to monitor cyclosporin therapy with the Neoral formulation. The favourable clinical results obtained with this approach have had an impact on reevaluating monitoring data for some of the other drugs. The newest drugs to reach clinical evaluation, sirolimus and everolimus, have been studied in the context of concentration-controlled dosing and there is a good rationale for their measurement. There have also been developments in the analytical techniques used, mostly to improve the selectivity of the assays or to adapt them to new monitoring strategies.

SUMMARY

Interpretation of drug concentration data is becoming ever more complex in this field as the number of potential drug combinations expands. The relatively narrow therapeutic index of these agents and the ever-present risk of clinically significant pharmacokinetic drug interactions makes drug monitoring an important aspect of their prescription.

Simultaneous quantification of sirolimus, everolimus, tacrolimus and cyclosporine by liquid chromatography-mass spectrometry (LC-MS)

We developed a universal liquid chromatography-mass spectrometry (LC-MS) assay with automated online extraction to quantify simultaneously the immunosuppressants sirolimus, everolimus, tacrolimus, and cyclosporine. Whole blood (300 microl) plus 6 microl 32-desmethoxyrapamycin (1 ng/microl) as internal standard was treated with 600 microl methanol/0.2 M ZnSO4 (80/20 v/v). After vortexing (30 s) and centrifugation (20000 g, 5 min) 50 microl of the supernatant were loaded on an extraction column, were washed by 0.35 ml/min water for 3 min and, after activation of a column-switching valve, were back-flushed by 0.25 ml/min methanol/ water (90/10 v/v) onto a C18 analytical column. After 22 min the extraction column was washed for 2 min with methanol and for 3 min with water before starting the next run. Column temperatures were kept at 33 degrees C. Sodium adduct ions [M+Na]+ ions were detected in the selected ion mode. For sirolimus, everolimus and tacrolimus the assay was linear from 0.3 to 200 microg/l and for cyclosporine from 5 to 1000 microg/l (all r2>0.999). Recovery of all immunosuppressants and the internal standard was >90% and in general, inter-day and intraday precision was <10%. The simultaneous quantification of blood levels by LC-MS seems to be the method of choice in transplanted patients receiving multiple immunosuppressants.