Antiproliferative and apoptotic effects of mycophenolic acid in human B-cell non-Hodgkin lymphomas

Post-transplant malignancy: Focusing on virus-associated etiologies, pathogenesis, evidence-based management algorithms, present status of adoptive immunotherapy and future directions

Modern immunosuppression has led to a decrease in rejection rates and improved survival rates after solid organ transplantation. Increasing the potency of immunosuppression promotes post-transplant viral infections and associated cancers by impairing immune response against viruses and cancer immunoediting. This review reflects the magnitude, etiology and immunological characteristics of various virus-related post-transplant malignancies, emphasizing the need for future research. A multidisciplinary and strategic approach may serve best but overall literature evidence targeting it is sparse. However, the authors attempted to provide a more detailed update of the literature consensus for the prevention, diagnosis, management and surveillance of post-transplant viral infections and associated malignancies, with a focus on the current role of adoptive immunotherapy and the way forward. In order to achieve long-term patient and graft survival as well as superior post-transplant outcomes, collaborative research on holistic care of organ recipients is imperative.

Mycosis Fungoides in Solid-Organ Transplant Recipients: A Multicenter Retrospective Cohort Study

BACKGROUND

Mycosis fungoides (MF) in solid-organ transplant recipients (SOTRs) is rare, with limited data on disease characteristics.

OBJECTIVE

The aim was to study the characteristics of MF in SOTRs with an emphasis on the immunosuppressive therapy.

METHODS

A retrospective cohort of patients diagnosed with MF, who were also SOTRs, were followed at 3 cutaneous lymphoma outpatient clinics, between January 2010 and February 2022.

RESULTS

Ten patients were included (7 male; median ages at transplantation and at diagnosis of MF were 33 and 48 years, respectively; 40% were diagnosed before the age of 18 years). Median time from transplantation to diagnosis of MF was 8 years (range 0.5-22). Transplanted organs and immunosuppressive treatments included: liver (n = 5; 4 treated with tacrolimus, 1 with tacrolimus and prednisone), kidney (n = 3), liver and kidney (n = 1), and heart (n = 1), all treated with mycophenolic acid, tacrolimus, and prednisone. Nine had early-stage MF (IA - 4, IB - 5; 40% with early folliculotropic MF), treated with skin-directed therapies, in 2 combined with acitretin, achieving partial/complete response. One patient had advanced-stage MF (IIIA) with folliculotropic erythroderma, treated with ultraviolet A and narrow-band ultraviolet B with acitretin, achieving partial response. Immunosuppression was modified in 3. At last follow-up (median 4 years, range 1-8), no stage progression was observed; 5 had no evidence of disease, 5 had active disease (IA/IB - 4, III - 1).

CONCLUSIONS

MF in SOTRs is usually diagnosed at an early stage, with overrepresentation of folliculotropic MF, and of children. Immunosuppressive therapy alterations, not conducted in most patients, should be balanced against the risk of organ compromise/rejection. Disease course was similar to MF in immunocompetent patients, during the limited time of follow-up.

Mycophenolate Mofetil: A Friend or a Foe with PTCy and Tacrolimus Prophylaxis in HLA-Matched donors?

Adapted from the haploidentical literature, post-transplantation cyclophosphamide (PTCy) is increasingly being used with HLA-matched donors, generally with a calcineurin inhibitor, such as tacrolimus (Tac) with or without mycophenolate mofetil (MMF). Owing to its immunosuppressive, potentially antitumor, and antimicrobial properties, MMF is an attractive drug; however, it remains unclear how much benefit is gained when used with PTCy/Tac. To assess that, we compared PTCy/Tac (n=242) to PTCy/Tac/MMF (n= 144) in recipients of HLA-matched donors. In multivariate analysis, the PTCy/Tac/MMF group had a significantly higher risk of grade II-IV acute graft-versus-host disease (GVHD; hazard ratio (HR) 2.1, 95% confidence interval (CI) 1.6-2.8, p<0.001), and steroid-refractory/dependent acute GVHD (HR 4.8, 95% CI 2.4-9.6, p<0.001), yet a significantly lower risk of relapse (HR 0.5, 95% CI, 0.3-0.9, p=0.009) and better progression-free survival (PFS; HR 0.7, 95% CI 0.5-0.9, p=0.04). There was no difference in the risk of grade III-IV acute GVHD, chronic GVHD, non-relapse mortality, or overall survival. MMF was associated with prolonged neutrophil engraftment by 2 days, and a higher risk of bacterial infections. In an exploratory stool microbiome analysis (n=16), we noted a higher relative abundance of β-glucuronidase-producing bacteria in the MMF group, which may have a role in the pathogenesis of MMF-related GVHD. Our data suggest that the addition of MMF to PTCy/Tac for HLA-matched donor HCT does not provide any advantage for GVHD prevention. Further studies are needed to decipher this mechanism, and understand its role with PTCy-based prophylaxis.

Posttransplant Lymphoproliferative Disorder Following Kidney Transplantation: A Review

Posttransplant lymphoproliferative disorder (PTLD) is one of the most feared complications following kidney transplantation. Over a 10-year period, the risk of PTLD in kidney transplant recipients (KTRs) is 12-fold higher than in a matched nontransplanted population. Given the number of kidney transplants performed, KTRs who experience PTLD outnumber other organ transplant recipients who experience PTLD. Epstein-Barr virus infection is one of the most important risk factors for PTLD, even though 40% of PTLD cases in contemporary series are not Epstein-Barr virus-associated. The overall level of immunosuppression seems to be the most important driver of the increased occurrence of PTLD in solid organ transplant recipients. Reduction in immunosuppression is commonly accepted to prevent and treat PTLD. Although the cornerstone of PTLD treatment had been chemotherapy (typically cyclophosphamide-doxorubicin-vincristinr-prednisone), the availability of rituximab has changed the treatment landscape in the past 2 decades. The outcome of PTLD in KTRs has clearly improved as a result of the introduction of more uniform treatment protocols, improved supportive care, and increased awareness and use of positron emission tomography combined with computed tomography in staging and response monitoring. In this review, we will focus on the most recent data on epidemiology, presentation, risk factors, and management of PTLD in KTRs.

Reuse of Molecules for Glioblastoma Therapy

Glioblastoma multiforme (GBM) is a highly malignant primary brain tumor. The current standard of care for GBM is the Stupp protocol which includes surgical resection, followed by radiotherapy concomitant with the DNA alkylator temozolomide; however, survival under this treatment regimen is an abysmal 12-18 months. New and emerging treatments include the application of a physical device, non-invasive 'tumor treating fields' (TTFs), including its concomitant use with standard of care; and varied vaccines and immunotherapeutics being trialed. Some of these approaches have extended life by a few months over standard of care, but in some cases are only available for a minority of GBM patients. Extensive activity is also underway to repurpose and reposition therapeutics for GBM, either alone or in combination with the standard of care. In this review, we present select molecules that target different pathways and are at various stages of clinical translation as case studies to illustrate the rationale for their repurposing-repositioning and potential clinical use.

Therapeutic potential and molecular mechanisms of mycophenolic acid as an anticancer agent

Mycophenolic acid (MPA) is the active metabolite of mycophenolate mofetil (MMF), an immunosuppressive drug approved for the prophylaxis of allograft rejection in transplant recipients. Recent advances in the role of the type II isoform of inosine-5'-monophosphate dehydrogenase (IMPDH2) in the tumorigenesis of various types of cancer have called for a second look of MPA, the first IMPDH2 inhibitor discovered a hundred years ago, to be repurposed as an anticancer agent. Over a half century, a number of in vitro and in vivo experiments have consistently shown anticancer activity of MPA against several cell lines obtained from different malignancies and murine models. However, a few clinical trials have been conducted to investigate its anticancer activity in humans, and most of which have shown unsatisfactory results. Understanding of available evidence and underlying mechanism of action is a key step to be done so as to facilitate further investigations of MPA to reach its full therapeutic potential as an anticancer agent. This article provides a comprehensive review of non-clinical and clinical evidence available to date, with the emphasis on the molecular mechanism of action in which MPA exerts its anticancer activities: induction of apoptosis, induction of cell cycle arrest, and alteration of tumor microenvironment. Future perspective for further development of MPA to be an anticancer agent is extensively discussed, with the aim of translating the anticancer property of MPA from bench to bedside.

Liposomal Delivery of Mycophenolic Acid With Quercetin for Improved Breast Cancer Therapy in SD Rats

The present study explores the influence of mycophenolic acid (MPA) in combination therapy with quercetin (QC) (impeding MPA metabolic rate) delivered using the liposomal nanoparticles (LNPs). Mycophenolic acid liposome nanoparticles (MPA-LNPs) and quercetin liposome nanoparticles (QC-LNPs) were individually prepared and comprehensively characterized. The size of prepared MPA-LNPs and QC-LNPs were found to be 183 ± 13 and 157 ± 09.8, respectively. The in vitro studies revealed the higher cellular uptake and cytotoxicity of combined therapy (MPA-LNPs + QC-LNPs) compared to individual ones. Moreover pharmacokinetics studies in female SD-rat shown higher T 1 / 2 value (1.94 fold) of combined therapy compared to MPA. Furthermore, in vivo anticancer activity in combination of MPA-LNPs and QC-LNPs was also significantly higher related to other treatments groups. The combination therapy of liposomes revealed the new therapeutic approach for the treatment of breast cancer.

Influence of mTOR-inhibitors and mycophenolic acid on human cholangiocellular carcinoma and cancer associated fibroblasts

Background

The incidence of Cholangiocellular Carcinoma (CCA) is increasing in the western world. The tumour has a high proportion of desmoplastic stroma and is correlated with a worse prognosis when cancer associated myofibroblasts (CAFs) are present. Recent studies showed promising results after liver transplantation (LTx) in non-resectable early stage CCA. Mycophenolic acid (MPA) and the mTor inhibitor Everolimus are used to prevent organ rejection but recently were shown to exhibit an antiproliferative effect on CCA-cells. Little is known about the influence of immunosuppressive drugs on tumour cell proliferation and migration after paracrine stimulation by CAFs. Moreover, it is still unknown, which signaling pathways are activated following these specific cell-cell interactions.

Methods

CCA cell lines HuCCT1 and TFK1 were utilized for the study. CAFs were derived from resected CCA cancer tissue. Cell viability was measured by the crystal violet assay and tumour cell invasion was quantified using a modified co-culture transmigration assay. Semiquantitative cytokine-expression was measured using a cytokine-array. Protein expression and phosphorylation of ERK, STAT3 and AKT was determined by Western-blot analysis.

Results

CCA cells treated with MPA exhibited a dose related decrease in cell viability in contrast to Cyclosporine A (CSA) treatment which had no effect on cell viability. Everolimus significantly inhibited proliferation at very low concentrations. The pro-invasive effect of CAFs in co-culture transmigration assay was significantly reduced by Everolimus at a concentration of 1nM (p = 0.047). In contrast, MPA and CSA showed no effect on tumour cell invasion. Treatment of CAFs with 1nM Everolimus showed a significant reduction in the expression of IL 8, IL 13, MCP1, MIF and Serpin E1. CCA-cells showed significant increases in phosphorylation of ERK, STAT3 and AKT under the influence of conditioned CAF-media. This effect was suppressed by Everolimus.

Conclusions

The secretion of proinflammatory cytokines by CAFs may lead to increased activation of JAK/STAT3-, ERK- and AKT-signaling and increased migration of CCA-cells. Everolimus abrogates this effect and inhibits proliferation of CCA-cells even at low concentrations.

LTx for non-resectable early stage CCA is currently performed in several clinical studies. Consistent with a role for common immunosuppressants in inhibiting tumour cell-proliferation and -invasion, our study indicates that a combination of standard therapies with Everolimus and MPA is a promising therapy option to treat CCA following LTx.

Derivatives containing both coumarin and benzimidazole potently induce caspase-dependent apoptosis of cancer cells through inhibition of PI3K-AKT-mTOR signaling

Coumarins are a large family of compounds derived from a wide range of plants, fungi, and bacteria, and coumarin derivatives can have extremely variable structures and consequently diverse biological properties including antitumor activity. Compounds that bear a benzimidazole moiety are known to possess antitumor activity and a variety of other biological activities. High-throughput screening of a compound library identified a coumarin-containing and a benzimidazole-containing compound [#32, 7-(diethylamino)-3-(1-methyl-1H-benzimidazol-2-yl)-2H-chromen-2-one] that has potent anticancer activity. Evaluation of 17 additional analogs further identified three compounds with anticancer activity in 14 different human cancer cell lines. Fluorescence-activated cell sorting and western blotting analyses suggested that these compounds can induce caspase-dependent apoptosis. Real-time reverse transcriptase PCR analyses of 26 cancer-related genes revealed that seven genes (NPPB, ATF3, DDIT4, CDH10, TSPAN14, TXNIP, and AXL) were significantly upregulated and nine genes (PAGE4, LRP8, SNCAIP, IGFBP5, SLCO2A1, CLDN2, ESRRG, D2HGDH, and PDGFRA) were significantly downregulated. The most upregulated gene is natriuretic peptide precursor B (NPPB) or brain natriuretic peptide, which is increased by 7-, 27-, and 197-fold at 12, 24, and 48 h, respectively. The second most upregulated gene is ATF3, which is increased by 23-fold at the 48 h timepoint. PAGE4 and IGFBP5 are the two most downregulated genes, with a 17-fold reduction in both genes. The expression of several genes (DDIT4, PDGFRA, LRP8, IGFBP5) and western blotting data on key signaling proteins indicate that compound #32 significantly inhibits the PI3K-AKT-mTOR pathway, an intracellular signaling pathway critical in cell proliferation and apoptosis.

Rapamycin can restore the negative regulatory function of transforming growth factor beta 1 in high grade lymphomas

TGF-β1 (transforming growth factor beta 1) is a negative regulator of lymphocytes, inhibiting proliferation and switching on the apoptotic program in normal lymphoid cells. Lymphoma cells often lose their sensitivity to proapoptotic/anti-proliferative regulators such as TGF-β1. Rapamycin can influence both mTOR (mammalian target of rapamycin) and TGF-β signaling, and through these pathways it is able to enhance TGF-β induced anti-proliferative and apoptotic responses. In the present work we investigated the effect of rapamycin and TGF-β1 combination on cell growth and on TGF-β and mTOR signalling events in lymphoma cells. Rapamycin, an inhibitor of mTORC1 (mTOR complex 1) did not elicit apoptosis in lymphoma cells; however, the combination of rapamycin with exogenous TGF-β1 induced apoptosis and restored TGF-β1 dependent apoptotic machinery in several lymphoma cell lines with reduced TGF-β sensitivity in vitro. In parallel, the phosphorylation of p70 ribosomal S6 kinase (p70S6K) and ribosomal S6 protein, targets of mTORC1, was completely eliminated. Knockdown of Smad signalling by Smad4 siRNA had no influence on apoptosis induced by the rapamycin+TGF-β1, suggesting that this effect is independent of Smad signalling. However, apoptosis induction was dependent on early protein phosphatase 2A (PP2A) activity, and in part on caspases. Rapamycin+TGF-β1 induced apoptosis was not completely eliminated by a caspase inhibitor. These results suggest that high mTOR activity contributes to TGF-β resistance and lowering mTORC1 kinase activity may provide a tool in high grade B-cell lymphoma therapy by restoring the sensitivity to normally available regulators such as TGF-β1.

Short-term pharmacokinetic study of mycophenolate mofetil in neonatal swine

BACKGROUND

Mycophenolate mofetil (MMF) is an effective immunosuppressive agent that has been frequently used in laboratory animals including swine; however, the pharmacokinetic properties of MMF in swine have not been studied. This short-term study was designed to evaluate the feasibility and the pharmacokinetic profiles of MMF therapy in neonatal swine.

MATERIALS AND METHODS

Twelve neonatal pigs were randomized into four groups including one control and three treated groups with oral MMF administered at 0.5, 1, and 2 g/m(2)/d for 4 days, divided by 2 half-doses at 9:00 and 17:00 (except day 4 during which MMF was not administered at 17:00). Blood samples were collected at 9:00 on days 0, 2, 3 and 4 for complete blood count and hepatic/renal function examination; the trough concentration of plasma mycophenolic acid (MPA) was also determined. On days 2 and 4, blood was collected to determine the area under the curve (AUC) of plasma MPA concentration. Animal body-weight growth and manifestations of MMF side-effects such as anorexia, vomiting, and diarrhea were also observed.

RESULTS

MMF has no acute hepatic/renal toxicity in newborn pigs; however, less body-weight growth was observed in treated groups. In the control group, a spontaneous increase of lymphocyte count was observed; in contrast, MMF therapy with doses of 1 and 2 g/m(2)/d reduced both lymphocyte and monocyte counts of piglets. Oral MMF had high bioavailability in neonatal swine. MPA-AUC0-12h of doses 0.5, 1, and 2 g/m(2)/d was 22.00 ± 3.32, 57.57 ± 34.30, and 140.00 ± 19.70 μg × h/mL, respectively. Neither MPA trough concentration (MPA-C0), nor MPA maximum concentration (MPA-Cmax) or MPA-AUC0-6h had high correlation with MMF-dose. For surveillance of MPA exposure, MPA-C0 had significant correlation with MPA-AUC0-12h (Spearman's ρ = 0.933, AUC0-12h = 17.882 × C0 + 14.479, r(2) = 0.966).

CONCLUSION

To reach adequate drug exposure and to reduce dose-dependent side effects, an MMF dose of 1 g/m(2)/d is recommended to be used as an initial dose for immunosuppressive therapy in piglets, and MPA-C0 monitoring is the most practical strategy for experimental transplantation study.

Epidemiology of de novo malignancies after solid-organ transplantation: immunosuppression, infection and other risk factors

Organ transplantation is an increasingly used medical procedure for treating otherwise fatal end-stage organ diseases, and a large number of anti-rejection drugs have been developed to prolong long-term survival of both the individual and the transplanted organ. However, the prolonged use of immunosuppressive drugs is well known to increase the risk of opportunistic diseases, particularly infections and virus-related malignancies. Although transplant recipients experience a nearly twofold elevated risk for all types of de novo cancers, persistent infections with oncogenic viruses are associated with up to hundredfold increased risks. Women of the reproductive age are growing in number among the recipients of solid-organ transplants, but specific data on cancer outcomes are lacking. This article updates evidences linking iatrogenic immunosuppression, persistent infections with oncogenic viruses, other risk factors and post-transplant malignancies. Epidemiological aspects, tumourigenesis related to oncogenic viruses, clinical implications, as well as primary and secondary prevention issues are discussed to offer clinicians and researchers alike an update of an increasingly important topic.

Mycophenolic acid inhibits migration and invasion of gastric cancer cells via multiple molecular pathways

Mycophenolic acid (MPA) is the metabolized product and active element of mycophenolate mofetil (MMF) that has been widely used for the prevention of acute graft rejection. MPA potently inhibits inosine monophosphate dehydrogenase (IMPDH) that is up-regulated in many tumors and MPA is known to inhibit cancer cell proliferation as well as fibroblast and endothelial cell migration. In this study, we demonstrated for the first time MPA’s antimigratory and anti-invasion abilities of MPA-sensitive AGS (gastric cancer) cells. Genome-wide expression analyses using Illumina whole genome microarrays identified 50 genes with ≥2 fold changes and 15 genes with > 4 fold alterations and multiple molecular pathways implicated in cell migration. Real-time RT-PCR analyses of selected genes also confirmed the expression differences. Furthermore, targeted proteomic analyses identified several proteins altered by MPA treatment. Our results indicate that MPA modulates gastric cancer cell migration through down-regulation of a large number of genes (PRKCA, DOCK1, INF2, HSPA5, LRP8 and PDGFRA) and proteins (PRKCA, AKT, SRC, CD147 and MMP1) with promigratory functions as well as up-regulation of a number of genes with antimigratory functions (ATF3, SMAD3, CITED2 and CEAMCAM1). However, a few genes that may promote migration (CYR61 and NOS3) were up-regulated. Therefore, MPA’s overall antimigratory role on cancer cells reflects a balance between promigratory and antimigratory signals influenced by MPA treatment.

The metabolism of lymphomas

PURPOSE OF REVIEW

Cellular to animal to human studies are shedding light on metabolic pathways that contribute to sustaining lymphomagenesis. Old players with new metabolic tricks and new metabolic players come into the scene. The purpose of this review is to discuss the recent advances made in the field of lymphoma metabolism with special focus on the metabolic modulation of tumor promoting and suppressing pathways and, conversely, on the effect of these pathways on metabolite addiction.

RECENT FINDINGS

The basis for the high glucose uptake and glycolytic activity in lymphoma cells is now beginning to be understood. Recent findings suggest a greater role of nucleotide biosynthesis as a major driving force for glycolysis, especially during proliferation and cellular stress conditions. There is new evidence for an increasing contribution of glycine-folate metabolism deregulation in nucleotide biosynthesis, genome integrity and epigenetic maintenance. Expanding roles for MYC, PI3K and TP53 in regulating reactive oxygen production, glycolysis and glutaminolysis in lymphoma cells have been described. The identification of novel pathways has allowed the emergence of new 'antimetabolite' strategies to increase the therapeutic efficacy of current approaches.

SUMMARY

Metabolism in lymphomas must fulfill the general demands from cell proliferation and those specific to lymphomagenesis. Data emerging from preclinical studies are elucidating the metabolic pathways that contribute to maintaining the malignant phenotype in lymphomas. This has resulted in identification of novel pathways, some of which may have a clinical impact in the diagnosis, characterization and treatment of lymphoma subtypes.

[Progress of the liver transplantation programme in Hungary]

The history of organ transplantation in Hungary dates back to 50 years, and the first succesful liver transplantation was performed in the United States in that time as well. The number of patients with end stage liver disease increased worldwide, and over 7000 patients die in each year due to liver disease in Hungary. The most effective treatment of end-stage liver disease is liver transplantation. The indications of liver transplantation represent a wide spectrum including viral, alcoholic or other parenchymal liver cirrhosis, but cholestatic liver disease and acute fulminant cases are also present in the daily routine. In pediatric patients biliary atresia and different forms of metabolic liver disorders represent the main indication for liver transplantation. The results of liver transplantation in Hungary are optimal with over 80% long-term survival. For better survival individual drug therapy and monitoring are introduced in liver transplant candidates.

Plasma cell neoplasms in US solid organ transplant recipients

Transplant recipients have elevated risk for plasma cell neoplasms (PCNs, comprising multiple myeloma and plasmacytoma), but little is known about risk factors in the transplant setting. Through linkage of the US solid organ transplant registry with 15 state/regional cancer registries, we identified 140 PCNs in 202 600 recipients (1987-2009). PCN risk was 1.8-fold increased relative to the general population (standardized incidence ratio [SIR] 1.80, 95%CI 1.51-2.12). Among cases, 102 were multiple myeloma (SIR 1.41) and 38 were plasmacytoma (SIR 7.06). PCN incidence increased with age, but due to the rarity of PCNs in younger people in the general population, SIRs were highest in younger transplant recipients (p = 0.03). PCN risk was especially high in recipients who were Epstein-Barr virus (EBV) seronegative at transplantation (SIR 3.93). EBV status was known for 18 tumors, of which 7 (39%) were EBV positive. Following liver transplantation, PCN risk was higher in recipients with cholestatic liver disease (SIR 2.78); five of these cases had primary biliary cirrhosis (PBC). A role for primary EBV infection after transplantation is supported by the increased PCN risk in young EBV seronegative recipients and the presence of EBV in tumors. PBC may be another risk factor, perhaps by causing chronic immune activation.

A case report of acute myeloid leukemia after liver transplantation

Acute myeloid leukemia (AML) is a rare complication observed after liver transplantation and only a handful of cases have been reported until now. We report a case of acute promyelocytic leukemia (APL) after liver transplantation in a 50-year-old man. The case presentation was postodontectomy bleeding with an associative abnormal coagulation test 85 months after liver transplantation. A routine blood test, bone marrow test, chromosome analysis and examination of PML/RARα chimeric gene confirmed the diagnosis of APL and disseminated intravascular coagulation (DIC). Induction chemotherapy with all-trans retinoic acid, arsenic trioxide and daunorubicin was given to this patient and complete remission was achieved. The patient was subjected to DA (daunorubicin combined with cytarabine) and MA (mitoxantrone combined with cytarabine) regimens after remission induction to consolidate the chemotherapy for two courses of treatment, and subsequently subjected to arsenous acid chemotherapy on a periodic basis. Twenty-two months into the follow-up, sustained bone marrow remission was observed with the adapted treatment regimen.

Treating rheumatic patients with a malignancy

Management of patients with inflammatory rheumatic disease and a history of (or even a current) malignant disease poses some particular challenges. As direct evidence of the risk of (recurrent or de novo) malignancy in patients with a history of malignant disease is scarce, such a risk may be estimated indirectly from the principal carcinogenicity of the respective drug to be used or (also indirectly) from cancer reactivation data from the transplant literature. In general, cancer risk is increased in patients receiving combination immunosuppressive treatment, but the risk in patients receiving individual drugs (with the exception of alkylating agents) remains entirely unclear. Indirect evidence supports the intuitive concept that the risk of cancer decreases over time after a successful cancer treatment. The only two studies in rheumatic patients with a cancer history were small and have not been able to show an increase in cancer reactivation. The risk of reactivation also depends on the site and location of the prior malignancy. In conclusion, the decision to treat a patient with a history of cancer immunosuppressively should be shared by the rheumatologist and the oncologist. Once the decision is established, such patients need intensive and close monitoring.

Lymphoproliferative disorders after solid organ transplantation-classification, incidence, risk factors, early detection and treatment options

Posttransplant lymphoproliferative disorder (PTLD) is a heterogeneous disease group of benign and malignant entities. The new World Health Organisation classification introduced in 2008 distinguishes early lesions, polymorphic, monomorphic and classical Hodgkin lymphoma-type PTLD. Based on the time of appearance, early and late forms can be identified.PTLDs are the second most frequent posttransplantation tumors in adulthood, and the most frequent ones in childhood. The incidence varies with the transplanted organ-from 1%-2% following kidney transplantation to as high as 10% following thoracic organ transplantation-due to different intensities in immunosuppression. Immunocompromised state and Epstein-Barr virus (EBV) infection are the two major risk factors.In Europe and the US approximately 85% of PTLDs are of B-cell origin, and the majority are EBV-associated. Symptoms are often unspecific; extranodal, organ manifestations and central nervous system involvement is common. Early lesions respond well to a decrease in immunosuppression. Malignant entities are treated with rituximab, chemotherapy, radiotherapy and surgical therapy. Adoptive T-cell transfer represents a promising therapeutic approach. The prognosis is favorable in early PTLD, and poor in late PTLD. Five-year survival is 30% for high-grade lymphomas. The prognosis of EBV-negative lymphomas is worse.Lowering the risk of PTLD may be achieved by low dose maintenance immunosuppression, immunosuppressive drugs inhibiting cell proliferation, and special immunotherapy (e.g. interleukin-2 inhibitors). Early detection is especially important for high risk-e.g. EBV-negative-patients, where the appearance of EBV-DNA and the increase in its titer may help.

In rat renal fibroblasts, mycophenolic acid inhibits proliferation and production of the chemokine CCL2, stimulated by tumour necrosis factor-alpha

BACKGROUND AND PURPOSE

Renal fibroblasts play a pivotal role in the development of tubulointerstitial fibrosis, a condition highly predictive of progression towards end-stage renal disease. The present study investigated the anti-mitogenic and anti-inflammatory effects of an inhibitor of inosine monophosphate dehydrogenase, mycophenolic acid (MPA) and the mechanisms underlying its action in normal rat kidney fibroblasts (49F cells).

EXPERIMENTAL APPROACH

Proliferation of 49F cells was studied by tetrazole 3-(4, 5-dimethylthiazol-2-yl-)-2,5-diphenyltetrazolium bromide (MTT) test, bromodeoxyuridine incorporation and flow cytometry. The cyclins, tumour suppressor genes and phospho-mitogen-activated protein kinases (MAPKs) were semiquantified by immunoblotting. Apoptosis was measured by quantifying the fragmented DNA and the activity of caspase 3. The monocyte chemokine CCL2 was measured by ELISA. The mRNA expression of CCL2 was measured by real-time PCR.

KEY RESULTS

Mycophenolic acid dose-dependently inhibited steady-state proliferation of 49F cells by up-regulation of p21, p27 and p53, in association with a decrease in cyclins D2 and E. Treatment with MPA also triggered apoptosis of 49F cells by activating the caspase 3 cascade. Furthermore, MPA attenuated tumour necrosis factor-alpha-induced CCL2 expression through down-regulation of p38 MAPK, but not that of ERK1/2 or JNK.

CONCLUSIONS AND IMPLICATIONS

The anti-mitogenic and anti-inflammatory effects of MPA were mediated by up-regulation of cell cycle inhibitors and pro-apoptotic signals, and by suppression of p38 MAPK pathway respectively. This dual effect of MPA may form the rationale for animal or clinical trials for the treatment of fibrotic renal diseases.

Critical Review of Preclinical Approaches to Evaluate the Potential of Immunosuppressive Drugs to Influence Human Neoplasia

Many immunosuppressive drugs are associated with an increased risk of B-cell lymphoma, squamous cell carcinoma, and Kaposi sarcoma. Thirteen immunosuppressive drugs have been tested in 2-year carcinogenicity studies (abatacept; azathioprine; busulfan; cyclophosphamide; cyclosporine; dexamethasone; everolimus; leflunomide; methotrexate; mycophenolate mofetil; prednisone; sirolimus; and tacrolimus) and in additional models including neonatal and genetically modified mice; chemical, viral, ultraviolet, and ionizing radiation co-carcinogenesis, and in models with transplanted tumor cells. The purpose of this review is to outline the mechanisms by which immunosuppressive drugs can influence neoplasia, to summarize the available preclinical data on the 13 drugs, and to critically review the performance of the models. A combination of primary tumor and metastasis assays conducted with transplanted cells may provide the highest value for hazard identification and can be applied on a case-by-case basis. However, for both small molecules and therapeutic proteins, determining the relative risk to patients from preclinical data remains problematic. Classifying immunosuppressive drugs based on their mechanism of action and hazard identification from preclinical studies and a prospective pharmacovigilance program to monitor carcinogenic risk may be a feasible way to manage patient safety during the clinical development program and postmarketing.

Notch-regulation upon Dll4-stimulation of TGFb-induced apoptosis and gene expression in human B-cell non-Hodgkin lymphomas

Notch-signalling has been implicated as a pathogenetic factor and a therapeutical target in T-cell leukaemias and in some lymphomas of B-cell origin. Our aim was to investigate the role of Notch-signalling in apoptosis regulation in human non-Hodgkin B-cell lymphoma (B-NHL) cell lines and in primary chronic lymhocytic leukaemia (CLL) cells using Delta-like 4 (Dll4) ligand mediated Notch activation and gamma-secretase inhibitor (GSI) mediated Notch inhibition in vitro. The potential cross-talk of Notch with the transforming growth factor-beta (TGFb) pathway in apoptosis induction was also explored, and the effect of GSI on drug-induced apoptosis was assessed. Modulation of Notch-signalling by itself did not change the rate of apoptosis in B-NHL cell lines and in CLL cells. TGFb-induced apoptosis was decreased - but not completely abolished - by GSI in TGFb-sensitive cell lines, but resistance to the apoptotic effects of TGFb were not reversed by Notch activation or inhibition. Drug-induced apoptosis was not modified by GSI. We identified Hairy/Enhancer of Split (HES)-1 as a TGFb target gene in selected - TGFb-sensitive - B-NHL cell lines. TGFb-induced HES-1 was only partially Notch-dependent in later phases. Apoptosis regulation by TGFb and GSI was not dependent on the transcriptional regulation of c-myc. In conclusion, our data does not support a unifying role of Notch in regulating apoptosis in B-NHL, but warns that gamma-secretase inhibitors may actually counteract apoptosis in some cases.

Mycophenolic acid inhibits maturation and function of human dendritic cells and B cells

Mycophenolic acid (MPA) is considered an immunosuppressive compound mainly because of its inhibitory effects on lymphocyte proliferation. Here we studied specifically the effects of MPA on the ability of dendritic cells (DCs) to activate T cells via the indirect pathway and on the maturation and function of B-lineage cells. We demonstrated that DC cell-surface receptors, associated with antigen uptake and antigen processing and presentation (CD83 and CD205), were differentially downregulated in the presence of MPA, translating into a decreased uptake of alloantigens and reduced stimulation of T cells with decreased cytokine secretion (interleukin (IL)-1Ra and transforming growth factor (TGF)-alpha). Similarly, MPA significantly inhibited B-cell differentiation into memory and plasma cells in vitro and decreased secretion of TNF-alpha, IL-1Ra, and IL-10. We further demonstrated for the first time that not only the amount of antibody secretion was significantly lowered in the presence of MPA but also the total number of antibody-producing cells was reduced. Importantly, we provide direct evidence that HLA-specific antibody secretion was also affected using a newly developed HLA antibody-specific B-cell enzyme-linked immunospot assay. Our data indicate additional pathways by which MPA downregulates the immune system. This in turn may lead to improved conditions for allograft tolerance and control of allograft rejection.

[Post-transplantation malignant tumors and the challenges of immunosuppressive therapy in transplanted patients developing lymphoma. Mycophenolic acid as a possibility]

The increasing frequency of malignant tumors developing during chronic immunosuppression is an important determinant of the long-term survival of organ transplanted patients. This problem can be solved only if we are aware of the special characteristics concerning our patients. The incidence and frequency of tumors occurring in kidney transplant recipients differ from those of the Hungarian population. The increased tumor risk resulting from chronic renal failure, increasing age of prospective kidney recipients and, in addition, the increasing frequency of tumors diagnosed in the early post-transplantation period emphasize the importance of regular oncological screening of patients on the waiting list. Early diagnosis and treatment of tumors and precancerous conditions are equally important in transplanted patients as well, and the tumor risk could be decreased by applying low dose immunosuppression and the preferential usage of immunosuppressive drugs with an oncologically favorable effect. The prognosis of post-transplantation tumors is poor, as they respond poorly to therapy. Lymphomas are of great importance because of their frequency. Different immunosuppressive regimens represent varying degrees of risk in lymphoma development. This risk is lower in the case of mycophenolic acid. The composition of immunosuppression is a major factor in treatment; an oncologically ideal compound would prevent organ rejection and, at the same time, would not counteract oncological therapy. We have shown that mycophenolic acid inhibits the proliferation of human B-cell non-Hodgkin lymphomas and induces apoptosis by activating the intrinsic pathway, both in vitro and in vivo. The favorable properties of mycophenolic acid suggest that it can provide the necessary immunoprotection for the transplanted organ and, given its anti-lymphoma effects, it may also prove useful in the therapy of lymphoma patients. It may also be helpful in the treatment of "traditional" lymphomas of the non-transplanted population, where the major cause of therapeutical failure is the development of apoptosis resistance. Mycophenolic acid, combined with other chemotherapeutical drugs, may enhance apoptosis in lymphoma cells. Our promising experimental results provide a basis for further, clinical studies.

Different effects of FK506, rapamycin, and mycophenolate mofetil on glucose-stimulated insulin release and apoptosis in human islets

Pancreatic islet transplantation has the potential to be an effective treatment for type 1 diabetes mellitus. While recent improvements have improved 1-year outcomes, follow-up studies show a persistent loss of graft function/survival over 5 years. One possible cause of islet transplant failure is the immunosuppressant regimen required to prevent alloimmune graft rejection. Although there is evidence from separate studies, mostly in rodents and cell lines, that FK506 (tacrolimus), rapamycin (sirolimus), and mycophenolate mofetil (MMF; CellCept) can damage pancreatic beta-cells, there have been few side-by-side, multiparameter comparisons of the effects of these drugs on human islets. In the present study, we show that 24-h exposure to FK506 or MMF impairs glucose-stimulated insulin secretion in human islets. FK506 had acute and direct effects on insulin exocytosis, whereas MMF did not. FK506, but not MMF, impaired human islet graft function in diabetic NOD*scid mice. All of the immunosuppressants tested in vitro increased caspase-3 cleavage and caspase-3 activity, whereas MMF induced ER-stress to the greatest degree. Treating human islets with the GLP-1 agonist exenatide ameliorated the immunosuppressant-induced defects in glucose-stimulated insulin release. Together, our results demonstrate that immunosuppressants impair human beta-cell function and survival, and that these defects can be circumvented to a certain extent with exenatide treatment.

Long-term risk of malignancy among patients treated with immunosuppressive agents for ocular inflammation: a critical assessment of the evidence

PURPOSE

To critically assess potentially carcinogenic effects of immunosuppressive therapy in the ocular inflammation setting.

DESIGN

Focused evidence assessment.

METHODS

Relevant publications were identified by MEDLINE and EMBASE queries and reference list searches.

RESULTS

Extrapolation from transplant, rheumatology, skin disease, and inflammatory bowel disease cohorts to the ocular inflammation setting suggest that: 1) alkylating agents increase hematologic malignancy risk and cyclophosphamide increases bladder cancer risk, but less so with < or =18 months' duration of therapy and hydration, respectively; 2) calcineurin inhibitors and azathioprine probably do not increase total cancer risk to a detectable degree, except perhaps some other risk factors (uncommon in ocular inflammation patients) might interact with the former to raise risk; 3) tumor necrosis factor (TNF) inhibitors may accelerate diagnosis of cancer in the first six to 12 months, but probably do not increase long-term cancer risk; and 4) changes in risk with methotrexate, mycophenolate mofetil, and daclizumab appear negligible, although nontransplant data are limited for the latter agents. Immunosuppression in general may increase skin cancer risk in a sun exposure-dependent manner.

CONCLUSION

Use of alkylating agents for a limited duration seems justifiable for severe, vision-threatening disease, but otherwise cancer risk may be a relevant constraint on use of this approach. Antimetabolites, daclizumab, TNF inhibitors, and calcineurin inhibitors probably do not increase cancer risk to a degree that outweighs the expected benefits of therapy. Monitoring for skin cancer may be useful for highly sun-exposed patients. Data from ocular inflammation patients are needed to confirm the conclusions made in this analysis by extrapolation.

Cancers after renal transplantation

For patients with end-stage kidney failure, kidney transplantation improves both their quality of life and overall life expectancy compared with dialysis, but it is not without adverse effects. Cancer is second to cardiovascular disease as one of the major causes of morbidity and mortality in renal transplant recipients. Prolonged use of modern immunosuppression, which leads to alteration of immune function and immune surveillance, is associated with increased cancer risk. There is now convincing evidence from observational studies and registry data to confirm a 3- to 5-fold increase in overall cancer incidence, with viral-related neoplasia incurring the greatest risk when compare with the general population. Despite the increased risk, little is known about the overall cancer prognosis, screening, treatment strategies, and effectiveness in this population. Cancers can recur, occur de novo, and be transmitted from donor organs posttransplantation. Uncertainties exist as to how modern immunosuppressive agents impact on cancer management and outcomes in these patients, with some agents such as calcineurin inhibitors and azathioprine, being more carcinogenic than others. The newer agents, proliferation signal/mammalian target of rapamycin inhibitors and mycophenolate mofitil, may have some antiproliferative and antitumor activities demonstrated in preclinical and clinical studies, but long-term well-powered trial data are needed to determine whether they are either protective or curative for cancers in renal transplant recipients. In this review, the incidence, etiology, prognosis, and potential approaches to cancer screening and management post-renal transplantation are discussed.