Recent advances in precision medicine for individualized immunosuppression

PURPOSE OF REVIEW

The current tools to proactively guide and individualize immunosuppression in solid organ transplantation are limited. Despite continued improvements in posttransplant outcomes, the adverse effects of over-immunosuppression or under-immunosuppression are common. The present review is intended to highlight recent advances in individualized immunosuppression.

RECENT FINDINGS

There has been a great focus on genomic information to predict drug dose requirements, specifically on single nucleotide polymorphisms of CYP3A5 and ABCB1. Furthermore, biomarker studies have developed ways to better predict clinical outcomes, such as graft rejection.

SUMMARY

The integration of advanced computing tools, such as artificial neural networks and machine learning, with genome sequencing has led to intriguing findings on individual or group-specific dosing requirements. Rapid computing allows for processing of data and discovering otherwise undetected clinical patterns. Genetic polymorphisms of CYP3A5 and ABCB1 have yielded results to suggest varying dose requirements correlated with race and sex. Newly proposed biomarkers offer precise and noninvasive ways to monitor patient's status. Cell-free DNA quantitation is increasingly explored as an indicator of allograft injury and rejection, which can help avoid unneeded biopsies and more frequently monitor graft function.

Treating children with inflammatory bowel disease: Current and new perspectives

Inflammatory bowel disease (IBD) is a chronic inflammatory condition of the gut characterised by alternating periods of remission and relapse. Whilst the mechanism underlying this disease is yet to be fully understood, old and newer generation treatments can only target selected pathways of this complex inflammatory process. This narrative review aims to provide an update on the most recent advances in treatment of paediatric IBD. A MEDLINE search was conducted using “paediatric inflammatory bowel disease”, “paediatric Crohn’s disease”, “paediatric ulcerative colitis”, “treatment”, “therapy”, “immunosuppressant”, “biologic”, “monitoring” and “biomarkers” as key words. Clinical trials, systematic reviews, and meta-analyses published between 2014 and 2016 were selected. Studies referring to earlier periods were also considered in case the data was relevant to our scope. Major advances have been achieved in monitoring the individual metabolism, toxicity and response to relevant medications in IBD including thiopurines and biologics. New biologics acting on novel mechanisms such as selective interference with lymphocyte trafficking are emerging treatment options. Current research is investing in the development of reliable prognostic biomarkers, aiming to move towards personalised treatments targeted to individual patients.

Systematic review: recurrent autoimmune liver diseases after liver transplantation

BACKGROUND

Autoimmune liver diseases (AILD) constitute the third most common indication for liver transplantation (LT) worldwide. Outcomes post LT are generally good but recurrent disease is frequently observed.

AIMS

To describe the frequency and risk factors associated with recurrent AILD post-LT and provide recommendations to reduce the incidence of recurrence based on levels of evidence.

METHODS

A systematic review was performed for full-text papers published in English-language journals, using the keywords 'autoimmune hepatitis (AIH)', 'primary biliary cholangitis and/or cirrhosis (PBC)', 'primary sclerosing cholangitis (PSC)', 'liver transplantation' and 'recurrent disease'. Management strategies to reduce recurrence after LT were classified according to grade and level of evidence.

RESULTS

Survival rates post-LT are approximately 90% and 70% at 1 and 5 years and recurrent disease occurs in a range of 10-50% of patients with AILD. Recurrent AIH is associated with elevated liver enzymes and IgG before LT, lymphoplasmacytic infiltrates in the explants and lack of steroids after LT (Grade B). Tacrolimus use is associated with increased risk; use of ciclosporin and preventive ursodeoxycholic acid with reduced risk of PBC recurrence (all Grade B). Intact colon, active ulcerative colitis and early cholestasis are associated with recurrent PSC (Grade B).

CONCLUSIONS

Recommendations based on grade A level of evidence are lacking. The need for further study and management includes active immunosuppression before liver transplantation and steroid use after liver transplantation in autoimmune hepatitis; selective immunosuppression with ciclosporin and preventive ursodeoxycholic acid treatment for primary biliary cholangitis; and improved control of inflammatory bowel disease or even colectomy in primary sclerosing cholangitis.

Future Immunosuppressive Agents in Solid-Organ Transplantation

Objective

To review the pharmacology, pharmacokinetics, efficacy, and safety of mycophenolate sodium, everolimus, and FTY720.

Study Selection and Data Extraction

Clinical trials and abstracts evaluating mycophenolate sodium, everolimus, and FTY720 in solid-organ transplantation were considered for evaluation. English-language studies and published abstracts were selected for inclusion.

Data Synthesis

Mycophenolate sodium has recently been approved by the Food and Drug Adminstration for marketing in the United States; everolimus and FTY720 are immunosuppressive agents that may soon be available in the United States. These agents have proven efficacy in reducing the incidence of acute rejection in solid-organ transplantation. Clinical trials have shown that these newer agents are relatively well tolerated. The most common adverse events associated with these agents were gastrointestinal and hematologic effects (mycophenolate sodium); hyperlipidemia, increased serum creatinine, and hematologic effects (everolimus); and gastrointestinal effects, headache, and bradycardia (FTY720).

Conclusion

Mycophenolate sodium has been approved in some European countries and the United States. Everolimus has been approved in some European countries and a new drug application has been submitted to the Food and Drug Administration. FTY720 is currently in phase III clinical trials and submission to the Food and Drug Administration for approval is a few years away. The approval of these agents will furnish the transplant practitioner with even more options for immunosuppression.

Biotherapies targeting T and B cells: from immune suppression to immune tolerance

The field of immunotherapy has undergone a major rejuvenation with the development of monoclonal antibodies and fusion proteins targeting specialized receptors of T and B lymphocytes or cytokines relevant for the differentiation of these cells. This review will focus on autoimmunity, probably the field that benefited most from these new biological therapies that very significantly impacted the modalities of patient's care. The aim is to present the agents which constitute major disease modifying drugs for the treatment of chronic invalidating autoimmune diseases. In doing so, we shall distinguish between agents that globally depress immune responses and those that may selectively target the harmful autoimmune response over long-term while preserving the capacity of the host to react normally to exogenous antigens, in other words, agents promoting 'operational tolerance'.

An Overview of Transplant Immunosuppression--History, Principles, and Current Practices in Kidney Transplantation

From the historical first transplant in 1954 to the current transplant era, tremendous strides have been made in transplant immunology and immunosuppression. The most common immunosuppressive regimens use a combination of agents with differing modes of action to maximize efficacy and minimize the toxicities associated with each class of agent. The general categories of immunosuppressives are glucocorticoids, antimetabolites, calcineurin inhibitors, anti-lymphocyte antibody therapies (monoclonal and polyclonal), costimulation blockers, and mTOR inhibitors. This article reviews immunosuppressant medications, their actions, and significant side effects; discusses clinical management issues of immunosuppression; and describes future directions for the development of immunosuppressive medications.

Trends of Immunosuppression and Outcomes Following Liver Transplantation: An Analysis of the United Network for Organ Sharing Registry

Advances in immunosuppression (IS) agents and strategies have resulted in reduced rejection rates and improved survival outcomes after liver transplantation. The use of induction and maintenance IS agents is both associated with reductions in acute rejection (AR) risk within the first 6 to 12 months posttransplant and with superior failure-free survival. With the lowered incidence of allograft losses attributable to rejection, the long-term sequelae of IS have become the major therapeutic challenge. The long-term use of calcineurin inhibitors and corticosteroids in maintenance immunotherapy regimens has been implicated in the development of renal dysfunction, infections, metabolic derangements, de novo and recurrent malignancies, and the propagation of hepatitis C virus reinfection. Our analysis of the United Network for Organ Sharing registry shows the use of induction and maintenance therapy is each associated with reductions in AR risk, thereby improving post-transplant survival. The administration of intensive induction regimens appears to be safe and exhibits an additive beneficial effect. Therefore, the use of intensive induction regimens may be warranted to allow for reductions in long-term maintenance IS to minimize drug toxicities while preserving graft outcomes.

Present state of immunosuppressive therapy in liver transplant recipients

1. Our increasing understanding of the signaling pathways and cellular interactions in transplant immunobiology has facilitated targeted strategies using novel immunosuppressive agents. 2. The pattern of immunosuppressive drug use in the United States continues to change, and the changes include the use of antibody induction therapy and the agents used in maintenance therapy. 3. The driving forces behind the development of new immunosuppressive regimens are the long-term complications of current immunosuppressive regimens (particularly renal dysfunction and metabolic disturbances).

Liver transplantation: where we are and where we are heading

Outcomes after liver transplantation are outstanding; however, the limiting factor is the shortage of organs. Recently, the utilization of donors after cardiac death has been encouraged; however, such transplants are associated with a high complication rate, mainly a high incidence of biliary complications, particularly ischemic cholangiopahty, a serious complication that often leads to retransplantation. The second problem is the morbidity associated with the use of immunosuppressive drugs. In this manuscript, the current status of clinical protocols for induction of tolerance is briefly discussed. Furthermore, the future of research in transplantation will involve basic scientists and clinical scholars working in concert as has been developed at Stanford School of Medicine with the creation of the Institute for Immunity, Transplantation and Infection.

The current trend of induction and maintenance treatment in patient of different PRA levels: a report on OPTN/UNOS Kidney Transplant Registry data

We investigate the status of sensitization in kidney transplant recipients and analyze the trend of induction and maintenance therapy in patients of different PRA levels. Despite the fact of the decreased percentages of kidney transplant recipients with presensitization history, the mean PRA levels of all kidney recipients has been increasing in the last 7 years, which is possibly due to the introduction of more sensitive antibody testing techniques or the tendency for kidney allocation organization and clinicians to give priority to patients with elevated PRA once a compatible donor kidney becomes available. The percentage of patients with treated rejection episodes within one year post-transplant were significantly higher in sensitized patients (PRA = 50-100:14.3%, and PRA = 1-49%: 13.9%) than in non-sensitized patients (12.4%). Both 1- and 5-yr graft survival rates have improved in the last 10 years; this was more significant in high PRA patients. Thymoglobulin was the most commonly used induction agent in last 10 years. Its users increased from 10% to 46% in non-sensitized patients, from 12% to 57% in PRA = 1-49% patients, and from 19% to 63% in PRA = 50-100% patients. The users of Campath, IVIg, and Rituximab have been increasing and reached 16%, 20%, and 11% in highly sensitized patients. In the last 5 years, steroid-free patients were 33-36%, 30-37%, and 10-25% for patients with PRA levels of 0, 1-49, and 50-100 respectively. Almost 90% of patients were on Prograf at discharge. Myfortic users have been increasing since 2005 and it may soon replace MMF if long-term follow-up study confirms its safety and efficacy.

Renal transplantation today

BACKGROUND

The first successful renal transplant was carried out more than five decades ago between identical twins. At these early days, acute rejection was the limiting factor.

DISCUSSION

Due to tremendous progress in immunosuppressive therapy and surgical technique, today, renal transplantation is the gold standard therapy for patients with end-stage renal disease. In fact, in comparison with chronic hemodialysis, renal transplantation offers an increase in quality of life while reducing comorbidities associated with dialysis treatment.

RESULTS

Despite numerous beneficial achievements, no further improvement regarding patient outcome can be observed over the last two decades. Graft survival rates remain unchanged. The leading causes for graft loss are chronic allograft nephropathy and death with functioning graft. This might be related to a constant increase of the proportion of donors presenting extended donor criteria as well as a more liberal acceptance of candidates for a renal transplant.

CONCLUSION

In the near future, one has to focus more closely on the posttransplant patient care to minimize factors associated with chronic allograft damage. These include post-transplant diabetes, hyperlipidemia, high blood pressure, cytomegalovirus infection, etc.

European research on cell and organ transplantation: towards novel opportunities?

Recent developments in basic and translational immunology open new exciting perspectives for clinical cell and organ transplantation, including the development of novel immunosuppressive agents, new diagnostic tools and validation of biomarkers for the prediction of rejection as well as the induction of tolerance. With respect to tolerance, a number of hurdles still need to be overcome before immunosuppressive drugs can be safely minimized or withdrawn in solid organ transplant recipients. Indeed, the human immune system appears more resistant to tolerance induction than expected from experimental studies in animals. Furthermore, the basic ethical principle 'primum non-nocere' prevents the implementation of clinical protocols endowed with a significant risk for graft and/or patient survival. With this background, the European Commission recently launched several initiatives to tackle unmet needs in transplantation medicine. Herein, we focus attention on the ongoing collaborative effort across the European Union aiming at identifying the current priorities requiring better integration of resources dedicated to transplantation research.

Pancreas and islet cell transplantation in diabetes

PURPOSE OF REVIEW

The following review of the field of whole organ pancreas and islet cell transplantation for type 1 diabetes mellitus is timely and relevant, since new findings and outcomes in both fields have emerged in the recent past.

RECENT FINDINGS

Research in the field of whole organ pancreas transplantation is characterized by small advances in knowledge in an established, but not widely used procedure. For islet transplantation, the field is evolving more rapidly. Disappointing clinical trial results, however, have hampered enthusiasm for this procedure. Islet transplantation research recently has focused on delineating possible causes of failure to achieve or sustain insulin independence and innovations to address both this failure and the current shortage of islets for clinical transplantation. Pancreas transplantation research is less innovative at this point, focusing mainly on optimizing clinical results.

SUMMARY

These published findings suggest that at the present time, clinical application of islet transplantation should be limited to clinical trials, focusing on techniques to enhance islet engraftment and survival. Whole organ pancreas transplantation remains the preferable transplant option for the type one diabetic patient.

Multiple sclerosis conference synopsis and discussion: cellular therapy for treatment of autoimmune diseases (October 2005)

At a conference held in October 2005, participants presented studies on high dose immunosuppression with hematopoietic cell transplant (HCT) for multiple sclerosis (MS), including neuroimmunological and magnetic resonance imaging (MRI) mechanistic approaches, clinical registry reports, and ongoing or newly-designed protocols. A discussion panel considered questions on how to define success, timing of controlled clinical trials, difficulty in patient recruitment, and future direction of high dose therapy.

Current trends in multiple sclerosis research: an update on pathogenic concepts

Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system (CNS) of presumed autoimmune origin which develops in a genetic susceptible individual triggered by additional environmental factors. In this review we will provide an update of basic pathogenic concepts. In addition, we will discuss newly evolving concepts in MS pathogenesis such as pathogenic heterogeneity, importance of axonal loss and the role of CD8+ T lymphocytes in tissue injury. In the last part of this review we will briefly describe currently approved MS treatments and summarize some promising therapeutic approaches that are currently under evaluation.

Costimulation blockade and its possible future use in clinical transplantation

The nonimmune effects of currently used immunosuppressive drugs result in a high incidence of late graft loss due to nephrotoxicity and death of patients. As an immune-specific alternative to conventional immunosuppressants, new biotechnology tools can be used to block the costimulation signals of T-cell activation. Many experimental studies--particularly preclinical studies in nonhuman primates--have focused on blocking the 'classical' B7/CD28 and CD40/CD40L pathways, which are critical in primary T-cell activation. Here, we review the limitations, the recent advances and the first large-scale clinical application of the CTLA4-Ig fusion protein to block the B7/CD28 costimulation pathway. We also focus on new B7/CD28 and tumor necrosis factor (TNF)/TNF-R family costimulatory molecules that can deliver positive or negative costimulation signals regulating the alloimmune response. Strategies that use single agents to block costimulation have often proved to be insufficient. Given the diversity of the different costimulation molecules, future strategies for human transplantation may involve the simultaneous blockade of several selected pathways or the simultaneous use of conventional immunosuppressants.

New trends in immunosuppression and immunotherapy

In the past years, research on immune regulation has exploded thanks to the re-emergence of T suppressor cells (Ts), now coined as regulatory T cells (Tregs). It has been established that different populations of Tregs exist in the immune system, and the generation, mechanism of suppression and the cellular and molecular targets of Tregs are being unraveled. This will lead to new opportunities for immune intervention to treat autoimmune disease and to achieve clinical transplantation tolerance. The scientific progress in the field of translational medicine was presented at the 7th International Conference on New Trends in Immunosuppression and Immunotherapy in Berlin in February 2006. In this special issue of International Immunopharmacology, several papers submitted to this congress will highlight some of the advances in this burgeoning field of translational medicine.

Critical issues of current and future developments in the treatment of immune thrombocytopenic purpura

B-cell depletion with rituximab has become a reasonable option for thrombocytopenic purpura (ITP) patients who are refractory for corticosteroids and/or splenectomy, with a response rate of about 55%. The side effects are mostly mild and easily manageable. Long lasting responses are likely in patients who achieve normal platelet counts. The mechanism of action of rituximab in immune-mediated disease in general and ITP in particular is not completely clear. Most probably, depletion of the memory B-cell compartment causes a decrease in autoantibody formation. To date it is impossible to predict the response to rituximab, although the presence of a high affinity Fc receptor for IgG seems to have positive predictive value. Future studies will have to clarify these issues, as well as possible effects of repeated rituximab treatment on primary and secondary immune responses.

The pharmacogenetics of calcineurin inhibitors: one step closer toward individualized immunosuppression?

The immunosuppressive drugs cyclosporin (CsA) and tacrolimus (Tac) are widely used to prevent acute rejection following solid-organ transplantation. However, the clinical use of these agents is complicated by their many side effects, a narrow therapeutic index and highly variable pharmacokinetics. The variability in CsA and Tac disposition has been attributed to interindividual differences in the expression of the metabolizing enzymes cytochrome P450 (CYP) 3A4 and 3A5, and in the expression of the drug transporter P-glycoprotein (encoded by the ABCB1 gene, formerly known as the multidrug resistance 1 gene). Variation in the expression of these genes could in turn be explained by several recently-identified single nucleotide polymorphisms (SNPs). Determination of these SNPs in (future) transplant recipients has the potential to identify individuals who are at risk of under-immunosuppression or the development of adverse drug reactions. Ultimately, genotyping for CYP3A and ABCB1 may lead to further individualization of immunosuppressive drug therapy for the transplanted patient.

New directions in cardiac transplantation

More than three decades of clinical experience in cardiac transplantation resulted in the spread of the procedure worldwide with a wealth of knowledge and advancements. Developments included liberalization of recipient and donor selection criteria, improved surgical techniques, novel immunosuppressive drugs and protocols, new rejection surveillance techniques, and better understanding of the pathophysiology of cardiac allograft vasculopathy to direct interventions for prevention and treatment.

B cell targeted therapies: safety considerations

Reported data from recent clinical trials have contributed substantially to our growing understanding of the potential effectiveness and safety of B cell targeted therapy in the treatment of rheumatic diseases. Trials with rituximab, an anti-CD20 monoclonal antibody that depletes mature B cells, have amassed the most data of any B cell targeted therapy to date. A number of other B cell directed therapies are under investigation. Interestingly, although they may share a common target, the different agents have quite distinct mechanisms of action, and therefore their efficacy and safety profiles may differ. A common concern with all B cell directed therapies is the potential effect these agents may have on humoral immunity. The safety profile of rituximab in the oncology setting is well known, based on a database of well over 370,000 patients. Phase II trials of rituximab in rheumatoid arthritis (RA) have begun to examine safety issues specifically in the RA population, including issues surrounding longterm and repeated treatment safety profiles. Questions about the longterm safety of B cell therapy remain to be clarified: What will be the safety profile for repeated treatment courses? What will be the safety profile when B cell targeted therapies are used in sequence or in conjunction with other agents? Answers to these important questions are likely to come from careful observations by treating clinicians, data from registries, and longterm followup of patients enrolled in clinical trials.

Updates from B Cell Trials: Efficacy

Recent reports of data from ongoing trials have contributed substantially to our growing understanding of the potential effectiveness and safety of B cell targeted therapy in the treatment of rheumatic diseases. In addition, the results have addressed practical questions regarding the administration of specific agents. Phase II trials of rituximab (RTX) have provided data supporting efficacy in rheumatoid arthritis (RA), including more clearly defining the role of glucocorticoids in the treatment and exploring the doses necessary to improve the signs and symptoms of RA. The Phase IIb Dose-Ranging Assessment International Clinical Evaluation of Rituximab in RA (DANCER) trial demonstrated that a significant percentage of patients achieved clinical improvement when treated with different doses of RTX as compared with those given placebo. The Phase III Randomized Evaluation of Long-Term Efficacy of Rituximab in RA (REFLEX) trial demonstrated efficacy of RTX in patients with a history of nonresponse to tumor necrosis factor inhibitors. Preliminary results of a small cohort of patients receiving RTX retreatment demonstrated efficacy with repeat administration. Phase II results of another B cell targeted therapy, anti-B lymphocyte stimulator protein, demonstrated efficacy. The efficacy of the agent, belimumab, resulted in an ACR20 response that was significantly higher in patients treated with belimumab versus placebo and in patients with RA. These findings support the hypothesis that B cells play an integral role in the pathogenesis of RA, and this report will review the efficacy results of clinical trials targeting B cells.

B cell targeted therapies in autoimmune diseases

In addition to rheumatoid arthritis (RA), B cells are likely to play a significant role in the development of other autoimmune rheumatic diseases, such as systemic lupus erythematosus (SLE), myositis, and vasculitis. Small-vessel vasculitis subtypes may be immune complex-mediated (cryoglobulinemia) or antineutrophil cytoplasmic antibody (ANCA)-associated; ANCA may be involved in the pathogenesis of vasculitis. In SLE, both antibody-associated and antibody-independent processes are almost certainly involved. B cell activity and autoantibody production are increased, while patients often have reduced peripheral B cells and abnormal B cell profiles. B lymphocyte stimulator (BLyS) protein regulates B cell activation and differentiation. For these reasons, B cells and the molecules that activate them are potential therapeutic targets in these diseases. Recent clinical trial data from small studies of rituximab (RTX) in SLE suggest that treatment improved clinical variables and measures of disease activity in patients, including those with central nervous system SLE. With retreatment, patients whose B cells were successfully depleted continued to show improvement in clinical and laboratory variables. Preliminary data suggest that treatment with RTX may be effective in ANCA-associated vasculitis. In addition a recent study showed significant benefit with myositis. Although these studies contain small cohorts of patients, they demonstrate that B cell-modulating therapies show promise in treatment of a variety of autoimmune diseases.

Crossroads of B cell activation in autoimmunity: rationale of targeting B cells

B cells have historically been considered as not preferentially involved in the immunopathogenesis of inflammatory joint diseases, in particular rheumatoid arthritis (RA), despite the notion that autoantibodies and immune complexes were involved in pathogenesis and served as diagnostic and classification markers. Following initial reports that patients with non-Hodgkin's lymphoma (NHL) and coexisting RA showed improvement in signs and symptoms of RA after anti-CD20 therapy, the role of B cells in autoimmune diseases was reexamined. Potential mechanisms can be inferred from what is known about the role of B cell functions, in particular antigen-experienced memory B cells. Activation of these cells can be dependent on T lymphocytes or independent of them. Once activated, the cells can efficiently act as antigen-presenting cells, can produce inflammatory cytokines, and may alternatively differentiate into antibody-producing plasma cells. These processes contribute to the activation of other immune cells and ultimately to joint destruction in RA. The development and maintenance of RA may be related to both direct and indirect involvement of these B cell-dependent processes. In systemic lupus erythematosus (SLE), the central pathogenic importance of autoimmune B cells is well recognized, based on early recognition of numerous autoantibodies and clinically important immune complexes. Based on the evidence supporting B cell involvement in the pathophysiology of autoimmune diseases, investigations are evaluating the clinical impact of B cell targeted therapies. B cell targeted therapies in human trials include an anti-B lymphocyte stimulator protein agent, belimumab; an anti-CD20 agent, rituximab; and an anti-CD22 antibody, epratuzumab.

Clinical transplantation: current problems, possible solutions

I have attempted to summarize the progress that has been made in organ transplantation in the past 50 years since the first identical twin transplant. For those who have worked long in this area its success has been remarkable. We currently expect patients to survive the operation and more than 90% of the graft to be functioning at a year with the half-life of the graft beyond 10 years, with some patients surviving into the fifth decade after kidney transplantation with grafts from unrelated donors and the fourth decade for liver transplants. Now the main stumbling block is shortage of organ donors and this is unlikely to be solved easily. There has been a considerable increase in donations from living volunteers and also the worry of immoral and illegal practices. In the future, we can expect considerable advances in immunosuppression with more effective, less toxic drugs and in some patients induction therapy that may approach tolerance so that no maintenance therapy will eventually be needed. Cell transplantation is likely to be developed as treatment for the clinic in the next 5-10 years, but developments of transplantation from animal to man still remains unsolved and unlikely to be successful in the clinic in the near future.

Changes in renal transplantation: comparison between two different series

BACKGROUND

New immunosuppressives have improved the results of renal transplants. However, the features of donors and recipients have changed, producing an increased age in both cases and more donors dying from strokes. We analyzed the impact of donor and recipient profile on survival of graft in recipients treated with new immunosuppressive agents.

METHODS

Data from 343 patients receiving cadaveric renal transplants functioning for 1 year on February of 1987 and March of 2001 when cyclosporine was incorporated in the immunosuppressive regimen. Two series were distinguished from the point of view of immunosuppression: an historical series and a current series. Graft survival rates were analyzed using the actuarial method. Multivariate analysis was achieved with Cox proportional hazards model.

RESULTS

Actuarial survival at 5 years was lower in the current series, 77%, as opposed to 82% in the historic series. Donor and recipient age, proteinuria, and losses in immediate postoperative period were significantly higher in the current series. However, acute rejection episode dropped from 54% to 21%. Delayed graft function also decreased from 18% to 10% in the current series. When multivariate analysis was performed of grafts functioning at 1 year, the relative risk was 3.12 in the historical series adjusted for other variables.

CONCLUSION

The data suggested that new immunosuppressive regimens counteract suboptimal features for donors and recipients.

Mechanisms of immune evasion by tumors

In the past decade, basic studies in animal models have begun to elucidate the physiological barriers which impede a successful antitumor immune response. These barriers operate at a number of levels, and involve the tumor, the tumor microenvironment and various components of the innate and adaptive immune systems. In this review, we discuss the multiple mechanisms by which tumors evade an immune response, with an emphasis on clinically relevant strategies to overcome these inhibitory checkpoints.

Cancer Immunosurveillance and Immunoediting: The Roles of Immunity in Suppressing Tumor Development and Shaping Tumor Immunogenicity

Cellular transformation and tumor development result from an accumulation of mutational and epigenetic changes that alter normal cell growth and survival pathways. For the last 100 years, there has been a vigorous debate as to whether the unmanipulated immune system can detect and eliminate such altered host derived cells despite the fact that cancer cells frequently express either abnormal proteins or abnormal levels of normal cellular proteins that function as tumor antigens. In this review, we discuss the current state of this argument and point out some of the recent key experiments demonstrating that immunity not only protects the host from cancer development (i.e., provides a cancer immunosurveillance function) but also can promote tumor growth, sometimes by generating more aggressive tumors. The terminology "cancer immunoediting" has been used to describe this dual host protective and tumor promoting action of immunity, and herein we summarize the ever-increasing experimental and clinical data that support the validity of this concept.

Immunosuppressive agents in solid organ transplantation: Mechanisms of action and therapeutic efficacy

Effective immunosuppression is an essential pre-requisite for successful organ transplantation and improvements in outcome after transplantation have to a large extent been dependent on developments in immunosuppressive therapy. Here we provide an overview of the different immunosuppressive agents currently used in solid organ transplantation. A historical perspective on the development of immunosuppression for organ transplantation is followed by a review of the individual agents, with a focus on their mechanism of action and efficacy. Steroids, anti-proliferative agents (azathioprine and mycophenolate), calcineurin inhibitors (cyclosporine and tacrolimus) and TOR inhibitors (sirolimus and everolimus) are discussed along with both polyclonal and monoclonal antibody preparations. Many of the key clinical trials that underpin current clinical usage of these agents are described and side-effects of the different agents are highlighted. Finally, a number of newer agents still in various stages of clinical development are briefly considered.

Outcomes and Complications After Heart Transplantation

In more than 35 years of experience with heart transplantation, improvements in patient selection, surgical techniques, organ preservation, and postoperative management have increased survival rates and reduced complications. However, a number of significant complications continue, limiting the benefit of heart transplantation as the long-term solution for patients. Current survival rates are 83% at 1 year and 72% at 5 years, with 50% of patients surviving 9.4 years or more. Recipient and donor characteristics influence survival outcome. Primary graft dysfunction is the most frequent cause of death during the first 30 days. The function of the transplanted heart allows return to pre-illness activities, though denervation limits peak exercise capacity. Advances in immunosuppressive medications have decreased the incidence and severity of rejection, though only recently have shown promise in attenuating the incidence of cardiac graft vasculopathy, the major complication limiting long-term graft function. This review addresses current outcomes and the short- and long-term complications of heart transplantation.

Mesenchymal stem cells: progress toward promise

Despite having access to embryonic stem cells, many laboratories choose to study adult stem cells, not because of philosophical reasons but because of the practical aspects and day-to-day progress necessary for developing cellular therapeutics. There is certainly the ethical desire and responsibility to provide patients with therapies where few options exist. Multipotential cells have been isolated from adult tissues in many laboratories, characterized and their multipotentiality examined. Mesenchymal stem cells (MSC) can be isolated from several tissues but easily accessible BM seems to be the most common source. These adult stem cells may not be as 'powerful' or diverse as embryonic stem cells may one day become, but at present they offer many advantages for developing cellular therapeutics: ease of isolation, expansion potential, stable phenotype, shippability, and compatibility with different delivery methods and formulations. Their potential use as cellular therapeutics has prompted the investigation of interactions of allogeneic MSC with the immune response. The great importance of cardiovascular medicine has demanded that MSC also be tested in this discipline. We believe MSC continue to provide a substantial scientific and therapeutic opportunity, and have reviewed some of the recent developments in the field.

Mesenchymal stem cells: progress toward promise

Despite having access to embryonic stem cells, many laboratories choose to study adult stem cells, not because of philosophical reasons but because of the practical aspects and day-to-day progress necessary for developing cellular therapeutics. There is certainly the ethical desire and responsibility to provide patients with therapies where few options exist. Multipotential cells have been isolated from adult tissues in many laboratories, characterized and their multipotentiality examined. Mesenchymal stem cells (MSC) can be isolated from several tissues but easily accessible BM seems to be the most common source. These adult stem cells may not be as 'powerful' or diverse as embryonic stem cells may one day become, but at present they offer many advantages for developing cellular therapeutics: ease of isolation, expansion potential, stable phenotype, shippability, and compatibility with different delivery methods and formulations. Their potential use as cellular therapeutics has prompted the investigation of interactions of allogeneic MSC with the immune response. The great importance of cardiovascular medicine has demanded that MSC also be tested in this discipline. We believe MSC continue to provide a substantial scientific and therapeutic opportunity, and have reviewed some of the recent developments in the field.

New trends in immunosuppression

Immunosuppressive agents are the mainstay treatment for patients that have received organ grafts and are becoming increasingly important in the treatment of autoimmune diseases. There are, however, many problems with both the concept and reality of long-term immunosuppression as a therapeutic modality, both in terms of the nonspecific toxicity of the drugs that are currently available and the increased risk of infections and tumours arising from global suppression of the immune system. This special issue of International Immunopharmacology includes papers submitted at the 6th International Conference on New Trends in Immunosuppression that was held in Salzburg during February 2004 that show some of the recent advances, particularly in the field of transplantation tolerance, and demonstrate the complexity of issues limiting our application of experimental developments into effective clinical strategies.

Individualized immunosuppression: new strategies from pharmacokinetics, pharmacodynamics and pharmacogenomics

BACKGROUND

The ultimate goal of transplantation is the donor-specific immune tolerance, but at least in the first 15 to 20 years of this century, immunosuppressive agents are still the determinant of clinical outcome of transplant recipients. Individualizing patient's immunosuppression to optimize the balance between therapeutic efficacy and the occurrence of adverse events poses a great challenge to physicians.

DATA SOURCES

The data in this article were taken mostly from MEDLINE (2000-2004), part of which were from the research of the authors.

RESULTS

Individualized immunosuppression remains a problem because of the narrow therapeutic index and wide inter- and intra-patient variation of commonly used immunosuppressants. Recent progress in study of pharmacokinetics and pharmacodynamics improved the clinical outcome of transplant recipients. More importantly, the emergence of pharmacogenomics might provide a promising and complementary tool for traditional therapeutic drug monitoring (TDM).

CONCLUSIONS

Individualizing organ recipient's immunosuppression to balance the therapeutic efficacy and the adverse events represents a great challenge to transplant clinicians. Pharmacogenomics shows great promise for an interesting and hopefully better future.

New Strategies in Immunosuppression

New immunosuppressive strategies that can prevent both acute and chronic rejection are being investigated to achieve graft tolerance and to minimize side effects and toxicity that may lead to graft loss. Drug pharmacokinetics and pharmacodynamics, as well as pharmacogenetics, all play a role in customizing treatment to the individual patient. To improve patient compliance, new drug formulations are on trial, such as the modified- release oral form of tacrolimus MR4 for once daily administration, which seems to be equivalent to bid administration in terms of steady-state exposure. Monoclonal/polyclonal antibodies are increasingly used in the induction phase in protocols where steroids are discontinued early. However, discontinuing steroids carries a high risk of acute rejection or organ failure in some subgroups of patients. The supposed benefit of steroid discontinuation may not be enjoyed by all patients. Minimizing anticalcineurin agents may prove to be similarly or even more advantageous. The use of new drugs and new combinations has greatly improved short-term transplant outcomes. The new goal is, therefore, to improve long-term results and particularly to prevent chronic rejection, thus increasing patient and organ survival.

Reduced endocannabinoid immune modulation by a common cannabinoid 2 (CB2) receptor gene polymorphism: possible risk for autoimmune disorders

Immune system responsiveness results from numerous factors, including endogenous cannabinoid signaling in immunocytes termed the "immunocannabinoid" system. This system can be an important signaling pathway for immune modulation. To assess the immunomodulating role of the cannabinoid 2 (CB2) receptor, we sought polymorphisms in the human gene, identified a common dinucleotide polymorphism, and investigated its effect on endocannabinoid-induced inhibition of T lymphocyte proliferation. The CB2 cDNA 188-189 GG/GG polymorphism predicts the substitution of glutamine at amino acid position 63 by arginine. T lymphocytes from CB2 188-189 GG/GG homozygotes had approximately twofold reduction of endocannabinoid-induced inhibition of proliferation compared with cells from CB2 188-189 AA/AA homozygotes. In GG/GG subjects, the reduced endocannabinoid inhibitory response was highly significant for N-arachidonylglycine and nearly significant for 2-arachidonylglycerol, and a specific CB2 receptor antagonist partially blocked these effects. Also, patients with autoimmune diseases had an increased prevalence of the homozygous GG/GG genotype. Collectively, these results demonstrate reduced endogenous fatty acid amide immunomodulatory responses in individuals with the CB2 188-189 GG/GG genotype and suggest that this CB2 gene variation may be a risk factor for autoimmunity. The results also support the proposition that the CB2 receptor may represent a novel pharmacological target for selective agonists designed to suppress autoreactive immune responses while avoiding CB1 receptor-mediated cannabinoid adverse effects.