Comparison between mycophenolate mofetil- and azathioprine-based immunosuppressions in clinical lung transplantation

Kidney Transplant Recipients Show Limited Lung Diffusion Capacity but Similar Hydrogen Peroxide Exhalation as Healthy Matched Volunteers: A Pilot Study

Patients with end-stage chronic kidney disease show higher systemic oxidative stress and exhale more hydrogen peroxide (H2O2) than healthy controls. Kidney transplantation reduces oxidative stress and H2O2 production by blood polymorphonuclear leukocytes (PMNs). Kidney transplant recipients (KTRs) may be predisposed to an impairment of lung diffusing capacity due to chronic inflammation. Lung function and H2O2 concentration in the exhaled breath condensate (EBC) were compared in 20 KTRs with stable allograft function to 20 healthy matched controls. Serum interleukin eight (IL-8) and C-reactive protein (CRP), blood cell counts, and spirometry parameters did not differ between groups. However, KTRs showed lower total lung diffusing capacity for carbon monoxide, corrected for hemoglobin concentration (TLCOc), in comparison to healthy controls (92.1 ± 11.5% vs. 102.3 ± 11.9% of predicted, p = 0.009), but similar EBC H2O2 concentration (1.63 ± 0.52 vs. 1.77 ± 0.50 µmol/L, p = 0.30). The modality of pre-transplant renal replacement therapy had no effect on TLCOc and EBC H2O2. TLCOc did not correlate with time after transplantation. In this study, TLCOc was less reduced in KTRs in comparison to previous reports. We suggest this fact and the non-elevated H2O2 exhalation exhibited by KTRs, may result perhaps from the evolution of the immunosuppressive therapy.

Immunosuppressive strategies in lung transplantation

Lung transplantation is a viable option for those with end-stage lung disease which is evidenced by the continued increase in the number of lung transplantations worldwide. However, patients and clinicians are constantly faced with acute and chronic rejection, infectious complications, drug toxicities, and malignancies throughout the lifetime of the lung transplant recipient. Conventional maintenance immunosuppression therapy consisting of a calcineurin inhibitor (CNI), anti-metabolite, and corticosteroids have become the standard regimen but newer agents and modalities continue to be developed. Here we will review induction agents, maintenance immunosuppressives, adjunctive therapies and other strategies to improve long-term outcomes.

Immunosuppression for Lung Transplantation: Current and Future

Purpose of the review

The number of lung transplantations performed worldwide continues to increase. There is a growing need in these patients for more effective immunosuppressive medications with less toxicity.

Recent findings

This review article summarizes the recent studies and developments in lung transplant immunosuppression. Novel immunosuppressive medications and strategies used in other solid organ transplantations are being trialed in lung transplantation. This includes the use of co-stimulation blockers like belatacept and mTOR inhibitors like everolimus. Calcineurin sparing regimens have been described in an attempt to minimize nephrotoxicity. Assays to measure the bioactivity of immunosuppressive medications to determine the global immune competence, such as Immuknow assay and Gamma interferon response are gaining traction.

Summary

Immunosuppression in lung transplant is evolving with the development of newer drugs and promising strategies to optimize immunosuppression. Further studies with multicenter randomized trials are required to increase the strength of the evidence.

New frontiers in immunosuppression

Immunosuppressive therapy is arguably the most important component of medical care after lung transplantation. The goal of immunosuppression is to prevent acute and chronic rejection while maximizing patient survival and long-term allograft function. However, the benefits of immunosuppressive therapy must be balanced against the side effects and major toxicities of these medications. Immunosuppressive agents can be classified as induction agents, maintenance therapies, treatments for acute rejection and chronic rejection and antibody directed therapies. Although induction therapy remains an area of controversy in lung transplantation, it is still used in the majority of transplant centers. On the other hand, maintenance immunosuppression is less contentious; but, unfortunately, since the creation of three-drug combination therapy, including a glucocorticoid, calcineurin inhibitor and anti-metabolite, there have been relatively modest improvements in chronic maintenance immunosuppressive regimens. The presence of HLA antibodies in transplant candidates and development of de novo antibodies after transplantation remain a major therapeutic challenge before and after lung transplantation. In this chapter we review the medications used for induction and maintenance immunosuppression along with their efficacy and side effect profiles. We also review strategies and evidence for HLA desensitization prior to lung transplantation and management of de novo antibody formation after transplant. Finally, we review immune tolerance and the future of lung transplantation to limit the toxicities of conventional immunosuppressive therapy.

Prevention of chronic rejection after lung transplantation

Long-term survival after lung transplantation (LTx) is limited by chronic rejection (CR). Therapeutic strategies for CR have been largely unsuccessful, making prevention of CR an important and challenging therapeutic approach. In the current review, we will discuss current clinical evidence regarding prevention of CR after LTx.

Targeting the Monocyte-Macrophage Lineage in Solid Organ Transplantation

There is an unmet clinical need for immunotherapeutic strategies that specifically target the active immune cells participating in the process of rejection after solid organ transplantation. The monocyte–macrophage cell lineage is increasingly recognized as a major player in acute and chronic allograft immunopathology. The dominant presence of cells of this lineage in rejecting allograft tissue is associated with worse graft function and survival. Monocytes and macrophages contribute to alloimmunity via diverse pathways: antigen processing and presentation, costimulation, pro-inflammatory cytokine production, and tissue repair. Cross talk with other recipient immune competent cells and donor endothelial cells leads to amplification of inflammation and a cytolytic response in the graft. Surprisingly, little is known about therapeutic manipulation of the function of cells of the monocyte–macrophage lineage in transplantation by immunosuppressive agents. Although not primarily designed to target monocyte–macrophage lineage cells, multiple categories of currently prescribed immunosuppressive drugs, such as mycophenolate mofetil, mammalian target of rapamycin inhibitors, and calcineurin inhibitors, do have limited inhibitory effects. These effects include diminishing the degree of cytokine production, thereby blocking costimulation and inhibiting the migration of monocytes to the site of rejection. Outside the field of transplantation, some clinical studies have shown that the monoclonal antibodies canakinumab, tocilizumab, and infliximab are effective in inhibiting monocyte functions. Indirect effects have also been shown for simvastatin, a lipid lowering drug, and bromodomain and extra-terminal motif inhibitors that reduce the cytokine production by monocytes–macrophages in patients with diabetes mellitus and rheumatoid arthritis. To date, detailed knowledge concerning the origin, the developmental requirements, and functions of diverse specialized monocyte–macrophage subsets justifies research for therapeutic manipulation. Here, we will discuss the effects of currently prescribed immunosuppressive drugs on monocyte/macrophage features and the future challenges.

Multiple regression analysis of factors predicting mycophenolic acid free fraction in 91 adult organ transplant recipients

BACKGROUND

Mycophenolic acid (MPA) is an antirejection drug used in various types of solid organ transplants. MPA is extensively bound to albumin, and free MPA is thought to be the primary immunosuppressive agent. Little is known of what contributes to the wide interindividual variability in the observed MPA free fraction (MPAf) in humans. The purpose of this study was to determine, using multiple regression analysis of demographic and laboratory variables that are routinely collected during clinic visits, patient factors that predict MPAf in a large sample (n = 91) of organ transplant recipients.

METHODS

Age, weight, height, total daily MPA dose, albumin, serum creatinine (SrCr), and MPAf were obtained from islet (n = 16), kidney (n = 28), and heart/lung (n = 47) transplant recipients. Multiple linear regression analysis and the The Spearman rank correlation were conducted using SigmaStat (version 3.5 for Windows). Significance was set a priori at P = 0.05.

RESULTS

The pooled data can be described as (mean ± SD) follows: age (52 ± 13 years), weight (72 ± 15 kg), height (169 ± 9 cm), total daily MPA dose (1632 ± 667 mg), albumin (42 ± 7 g/L), SrCr (112 ± 34 µmol/L), and MPAf (2.9% ± 3.5%). Multiple regression of all commonly acquired variables generated the following equation: MPAf = 1.865 + (0.0357 × age (yrs)) + (0.0125 × weight (kg)) - (0.0202 × height (cm)) - (0.000323 × total daily dose (mg)) + (0.0122 × albumin (g/L)) + (0.0160 × SrCr (µmol/L)) (r = 0.06), but none of the variables were significant predictors of MPAf (P > 0.05). The Spearman rank correlation of each individual variable confirmed lack of significant correlation with MPAf.

CONCLUSIONS

To our knowledge, this is the first study attempting to describe factors predicting MPAf in adult organ transplant recipients involving a large sample size. The novel findings of lack of significant predictors warrant further investigations using additional patient factors.

Mycophenolate monitoring in liver, thoracic, pancreas, and small bowel transplantation: a consensus report

Assessing the value of mycophenolic acid (MPA) monitoring outside renal transplantation is hindered by the absence of any trial comparing fixed-dose and concentration-controlled therapy. However, in liver and thoracic transplantation particularly, clinical trials, observational studies with comparison groups, and case series have described MPA efficacy, exposure/efficacy relationships, pharmacokinetic variability, and clinical outcomes relating to plasma MPA concentrations. On the basis of this evidence, this report identifies MPA as an immunosuppressant for which the combination of variable disposition, efficacy, and adverse effects contributes to interindividual differences seemingly in excess of those optimal for a fixed-dosage mycophenolate regimen. Combined with experiences of MPA monitoring in other transplant indications, the data have been rationalized to define circumstances in which measurement of MPA concentrations can contribute to improved management of mycophenolate therapy in nonrenal transplant recipients.

Mycophenolate mofetil reduces alveolar inflammation, acute rejection and graft loss due to bronchiolitis obliterans syndrome after lung transplantation

BACKGROUND

Bronchiolitis obliterans syndrome (BOS) is still the main complication after lung transplantation. Besides other improvements in post-operative management, newer immunosuppressive regimens might decrease the devastating sequelae of this complication.

METHODS

We compared the prospectively collected data of lung transplant recipients treated either with azathioprine (AZA; n = 48) or mycophenolate mofetil (MMF; n = 108), who underwent regular monthly surveillance bronchoscopies for at least 6 post-operative months.

RESULTS

Patients on MMF had significantly fewer acute (P < 0.001) and recurrent (P < 0.001), as well as less severe rejection episodes (P = 0.01). In addition, MMF significantly reduced the number of alveolar lymphocytes, eosinophils and neutrophils (P < 0.001), and decreased the hemosiderin score reflecting non-specific alveolar-capillary damage (P < 0.001). Although there was no change in the three stages of BOS, there was a trend towards improved survival (P = 0.062) and a significant decrease in graft loss due to BOS (P = 0.049) in patients receiving MMF.

CONCLUSIONS

Immunosuppression with MMF significantly decreased the incidence, severity and recurrence of acute rejection episodes in lung transplant recipients. Parameters of alveolar inflammation and alveolar-capillary damage were also decreased. As a potential consequence, MMF significantly reduced graft loss due to BOS and tended to improve overall survival in these patients.

Tacrolimus and azathioprine versus cyclosporine and mycophenolate mofetil after lung transplantation: a retrospective cohort study

BACKGROUND

The efficacy and safety of different combinations of immunosuppressive regimens after lung transplantation are unknown.

METHODS

We examined 120 consecutive transplant recipients between July 2001 and July 2005, of whom 37 received cyclosporine and mycophenolate mofetil (Cyc/MMF) and 83 received tacrolimus and azathioprine (Tac/Aza) as the initial immunosuppressive regimen along with an interleukin-2 antagonist induction therapy. The primary outcome was the rate of histologically confirmed acute rejection.

RESULTS

The rate of acute rejection did not vary by treatment regimen (0.42 vs 0.34 episodes per 100 person-days in Cyc/MMF and Tac/Aza groups, respectively, p = 0.22). The mean cumulative lymphocytic bronchiolitis score was greater in the Cyc/MMF group (1.8 +/- 1.9) compared with the Tac/Aza group (1.2 +/- 2.0; p = 0.03). Pulmonary function at 1 year was better in the Tac/Aza group, even when adjusted for recipient age, gender, and transplant procedure. Survival and the rate of bronchiolitis obliterans syndrome did not vary by group.

CONCLUSIONS

Outcomes after lung transplantation did not meaningfully vary between those assigned to Cyc/MMF compared with Tac/Aza combined with IL-2 inhibitor induction therapy.

Lung transplantation for cystic fibrosis: Current concepts and one center's experience

BACKGROUND

Although new approaches to the treatment of patients with cystic fibrosis (CF) are significantly prolonging their lives, most patients will eventually develop respiratory failure due to progressive bronchiectasis caused by chronic lung infection and inflammation and die from to respiratory failure. We examined our center's (University of Wisconsin Hospital and Clinics) experience with lung transplantation for patients with CF and reviewed the literature to examine current and evolving approaches to transplantation for this indication.

METHODS

We reviewed all published literature pertaining to lung transplantation for CF through 2006, and we reviewed all aspects of transplantation for patients with CF at our institution from 1994 to 2005.

RESULTS

Major complications following lung transplantation include acute rejection, bacterial infection, and bronchiolitis obliterans. Five-year survival at UWHC (Kaplan-Meier) is 67%, and survival was not adversely affected by transplanting patients receiving mechanical ventilation. The major cause of death for transplant recipients was bronchiolitis obliterans syndrome (BOS).

CONCLUSIONS

Lung transplantation for CF is associated with acceptable survival rates and can improve quality of life. Lung transplant should be offered to all patients with advanced CF lung disease if they meet currently accepted inclusion and exclusion criteria.

Critical care perspective on immunotherapy in lung transplantation

Lung transplantation is now a viable therapeutic option in the care of patients with advanced pulmonary parenchymal or pulmonary vascular disease. Lung transplantation, however, with chronic posttransplant immunosuppression, creates a uniquely vulnerable population of patients likely to experience significant life-threatening complications requiring intensive care. The introduction of several novel immunosuppressive agents, such as sirolimus and mycophenolate mofetil, in conjunction with more established agents such as cyclosporine and tacrolimus, has greatly increased treatment options for lung transplant recipients and likely contributed to improved short-term transplant outcomes. Modern transplant immunosuppression, however, is associated with a host of complications such as opportunistic infections, renal failure, and thrombotic thrombocytopenic purpura. The main focus of this review is to provide a comprehensive summary of modern immunotherapy in lung transplantation and to increase awareness of the serious and potentially life-threatening complications of these medications.

Lung Transplantation: Advances in Immunosuppression

Since the advent of various novel immunosuppressants, including tacrolimus, rapamycin, and daclixumab. expanding variations of protocols have been developed. Little evidence exists to substantially support a single agent over another. or a combination regimen protocol over another. Therefore, the principles and the goals of immunosuppression in lung transplantation recipients will remain moving targets and continue to evolve, and the use of large-scale, multi-institutional clinical trials is imperative to develop optimal immunosuppressive strategies.

Comparison of mycophenolate mofetil and azathioprine for prevention of bronchiolitis obliterans syndrome in de novo lung transplant recipients

BACKGROUND

There are no data on the effects of mycophenolate mofetil (MMF) on the incidence of bronchiolitis obliterans syndrome (BOS) in lung-transplant patients. This study attempted to determine whether MMF reduces the incidence of BOS in de novo lung transplant recipients compared with azathioprine (AZA).

METHODS

This prospective, randomized, open-label, multicenter study compared the effects of MMF with AZA in combination with induction therapy, cyclosporine (Neoral) and corticosteroids in patients receiving their first lung transplant. Primary endpoint was incidence of BOS at 3 years. Secondary endpoints were incidence of acute rejection, time to first rejection event, and survival.

RESULTS

The incidence of acute rejection and the time to first rejection event at 1 and 3 years did not differ between groups (54.1% vs. 53.8% and 56.6% vs. 60.3% for MMF and AZA respectively). Survival at 1 year tended to be better in patients receiving MMF (88 vs. 80%, P = 0.07). At year 3, there was no difference in survival or in the incidence, severity or time to acquisition of BOS between the two groups. Treatment was generally well tolerated, however more patients withdrew from AZA treatment than from MMF (59.6% vs. 46.5%, P = 0.02). As a result, there was an imbalance in the observation times of the two groups (876 +/- 395 vs. 947 +/- 326 days).

CONCLUSIONS

No differences were seen in the incidence of acute rejection or BOS in lung transplant recipients treated with MMF or AZA. This null result may have been influenced by the shorter observation time for AZA patients.

Experience with cyclosporine: from revolution to evolution of immunosuppressive protocols in thoracic organ transplantation

The introduction of cyclosporine into clinical practice of thoracic organ transplantation had a dramatic and positive effect on both short- and long-term survival. Today, the majority of patients are still treated with this drug, and different immunosuppressive combination therapies have further resulted in improved long-term survival. Such combinations to calcineurin inhibitors include prednisolone, mycophenolate mofetil, azathioprine, and Rapamycin. Based on data from our own institution 1- and 5-year survival rates of 86% and 78% can be obtained after heart transplantation and 76% and 59% after lung transplantation. Causes of death are described. Future immunosuppressive strategies will have to concentrate further on the omission of organ-damaging side effects. Also, not a single compound or combination for immunosuppression after thoracic organ transplantation has proved to be effective in cases with chronic rejection (eg, transplant vasculopathy in heart transplantation and bronchiolitis obliterans in lung transplantation). Moreover, with current survival data in mind, quality of life has to be considered a major focus for future designs of immunosuppressive protocols.

Use of cyclosporine in thoracic transplantation

The use of cyclosporine (CyA) in clinical thoracic transplantation has markedly improved the survival and quality of life of patients in the past 2 decades. In the mid-1990s a significant advance in formulation design took place with the introduction of Neoral. This new microemulsion formulation of CyA demonstrates reduced intersubject and intrasubject variability in absorption and improved oral bioavailability compared with the oil-based CyA formulation. Moreover, C2 measurements of CyA could result in an even better method to avoid overimmunosuppression. On the other hand, generic alternatives of CyA could potentially reduce costs to transplant recipients as well as to the general community. Since the initiation of tacrolimus, mycophenolate mofetil, and rapamycin, slow but expanding variations of immunosuppressive protocols have taken place. Transplantation medicine is thus becoming an increasingly exciting and innovative field, in which CyA continues to play a central role as the core immunosuppressant of choice for the majority of patients.

Mycophenolate mofetil in solid-organ transplantation

This review focuses on the use of mycophenolate mofetil (MMF) as an immunosuppressive agent in solid-organ transplantation. MMF, a non-competitive inhibitor of inosine monophosphate dehydrogenase, blocks de novo purine synthesis in T and B lymphocytes, resulting in the selective inhibition of proliferation of these cells in response to antigenic stimuli. MMF may also promote apoptosis of these cells. The immunosuppressive ability of MMF is thought to derive mainly from the inhibition of inosine monophosphate dehydrogenase. The other effects of MMF include suppression of antibody synthesis by B lymphocytes, inhibition of proliferation of smooth muscle cells in culture and impaired glycosylation of adhesion molecules. MMF may exhibit anti-inflammatory effects resulting from decreased activity of the inducible form of nitric oxide synthase, a consequence of depletion of tetrahydrobiopterin, which leads to decreased generation of peroxynitrite, a pro-inflammatory molecule. The pharmacokinetics, pharmacodynamics and principles underlying therapeutic drug monitoring of MMF are reviewed. The results of the pivotal clinical trials of MMF in kidney and heart transplantation are discussed and a summary of the major studies demonstrating a positive effect of MMF on renal transplantation outcomes is presented. The use of MMF in the context of ABO-incompatible renal transplantation, renal transplantation in highly sensitised and cross-match positive recipients, humoral rejection of renal allografts, chronic allograft nephropathy and steroid/calcineurin inhibitor minimisation in renal transplantation are also discussed.

Lung transplants with tacrolimus and mycophenolate mofetil: a review

Traditionally, immunosuppressive maintenance therapy in solid organ transplantation has consisted of cyclosporine (CsA), azathioprine, and prednisone. However, lung transplant recipients are far more frequently affected by acute rejection, especially during the first 6 months after the transplantation, than patients with other transplanted organs. Further, they display a greater risk for chronic transplant dysfunction and ultimate graft loss. Bronchiolitis obliterans syndrome (BOS) is the major cause of morbidity and mortality among long-term survivors after lung transplantation. Acute pulmonary allograft rejection has been identified as the major risk factor for the development of BOS. Based on favourable results in kidney, liver, and heart transplantation, tacrolimus and mycophenolate mofetil have been used as primary prophylaxis and as rescue therapy for recurrent or persistent acute rejection and BOS. A secondary indication is CsA toxicity. This review focuses on reported results of the combination of tacrolimus and mycophenolate mofetil in lung transplantation. These new immunosuppressive drugs have markedly improved the efficacy profiles without additional detrimental toxicities, and appear to be a safe alternative to CsA and azathioprine in patients following lung transplantation. However, at present, BOS is not influenced by these new drugs. The optimal long-term immunosuppressive regimen remains to be established.

Bronchiolitis obliterans syndrome

BOS remains a difficult problem to control following lung transplantation, largely because of uncertainties regarding the underlying mechanisms that are responsible for it. Continued work on the pathogenesis of BOS is essential. The progressive nature and poor outlook when BOS stage 3 is reached indicates that current strategies should be focused on prevention and early intervention. There is a great need for randomized, controlled trials on intervention if the international transplant community is to make progress in this area.

Cyclosporine A versus tacrolimus in combination with mycophenolate mofetil and steroids as primary immunosuppression after lung transplantation: one-year results of a 2-center prospective randomized trial

OBJECTIVES

Cyclosporine (INN: ciclosporin) A or tacrolimus have been used mostly in combination with azathioprine as primary immunosuppression after lung transplantation. Benefit or risk deriving from the combination with mycophenolate mofetil are yet unknown.

METHODS

In a prospective, 2-center, open randomized trial, the combination of cyclosporine A, mycophenolate mofetil, and steroids was compared with tacrolimus, mycophenolate mofetil, and steroids as primary therapy after primary lung transplantation. All patients underwent induction therapy with rabbit antithymocyte globulin for 3 days. The 2 groups were compared with regard to patient survival, freedom from acute rejection, bronchiolitis obliterans, infectious episodes, and side effects.

RESULTS

Between September 1997 and April 1999, 74 lung transplant recipients were randomized to receive either cyclosporine A (n = 37) or tacrolimus (n = 37). Groups were comparable with regard to age, sex, transplant procedure, and cytomegalovirus match. Mean follow-up was 507 +/- 258 and 508 +/- 248 days, respectively. Six- and 12-month survival was similar in both groups (89% vs 84% and 82% vs 71%, respectively; P =.748 at 12 months). Two patients from the cyclosporine A group were retransplanted. Freedom from acute rejection at 6 and 12 months was comparable between groups (46% vs 51% and 35% vs 46%, respectively; P =.774 at 12 months). The mean number of treated acute rejection episodes per 100 patient-days was higher in the cyclosporine A than in the tacrolimus group, but the difference was not statistically significant (0.32 +/- 0.42 vs 0.22 +/- 0.30, respectively; P =.097). Four patients from the cyclosporine A group had to be switched to tacrolimus to control ongoing rejection, whereas no patient from the tacrolimus group had to be switched to cyclosporine A. There was a trend toward more infections (0.7 +/- 0.36 vs 0.55 +/- 0.31, P =.059) in the cyclosporine A group. New-onset diabetes mellitus was observed in the tacrolimus group only (11% vs 0%, P =.151), whereas there was a higher incidence of hypertension (60% vs 11%, P =.03) in the cyclosporine A group.

CONCLUSION

This 2-center, prospective randomized study showed high immunosuppressive potency of both cyclosporine A and tacrolimus in combination with mycophenolate mofetil. No significant difference in incidence of acute rejection was observed between the 2 groups. Moreover, survival and incidence of infection were similar. Incidence of drug-related adverse events were similar, yet their spectrum was different.

VEGF-A and -C but not -B mediate increased vascular permeability in preserved lung grafts

BACKGROUND

Vascular endothelial growth factor (VEGF) is a potent endothelial cell growth and permeability factor, expressed in the lung. Overexpression of VEGF is associated with increased vascular permeability in the early stage of acute lung injury in mice. The role of various forms of VEGF in transplantation-induced lung injury is not well understood.

METHODS

VEGF mRNA and protein expression was measured in biopsies of preserved donor lung grafts as well as in control lung biopsies, using real-time reverse transcriptase-polymerase chain reaction and Western blot analysis. VEGF tissue expression was also evaluated by immunocytochemistry. Serum VEGF was measured in recipients after transplantation and in controls using ELISA.

RESULTS

Although VEGF-A and VEGF-C protein expression was up-regulated, their mRNA levels were decreased in donor versus control lung biopsies (P<0.05). VEGF-B mRNA was decreased, but its protein level was unchanged in donors. Flt-1 was unchanged, KDR gene expression was down-regulated in donors (P<0.05), and both receptors' protein expression was under the detection level in donor and control lungs. VEGF-A was detected in pulmonary vessels and bronchi, whereas VEGF-C was only detectable in vessels of both donor and control lungs. After transplantation, serum VEGF increased (P<0.05) and returned to control baseline levels 12 weeks after surgery. Wet-to-dry lung weight was increased in donor versus control lungs.

CONCLUSIONS

These results indicate that unventilated hypoxia increases vascular permeability in lung grafts and that this process is mainly regulated at VEGF-A and VEGF-C translational but not transcriptional level. Selective VEGF antagonism during graft preservation might be of benefit to counteract edema formation.

Consideration of mycophenolate mofetil for idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is an inflammatory disorder of the lungs of unknown etiology, with no effective treatment. Besides the recent finding of utility of mycophenolate mofetil (MMF) in a case of refractory interstitial lung disease associated with ulcerative colitis, I suggest that there are at least three other reasons to consider MMF for IPF. Previously, MMF has been found to be effective as salvage therapy in a number of diseases. MMF might work for IPF not only by white cell suppression, but also in vivo against proliferation of primary human pulmonary fibroblasts. There is one group of patients for whom, logically, MMF should be most strongly considered--those with a high likelihood of receiving a lung transplant. As MMF is often part of the post-transplant immunosuppressive regimen in these patients, logic would seem to dictate MMF should be considered for use before subjecting the patient to major surgery.

Results of a randomized, prospective, multicenter trial of mycophenolate mofetil versus azathioprine in the prevention of acute lung allograft rejection

BACKGROUND

Although the use of mycophenolate mofetil (MMF) has reduced the incidence of acute rejection in heart and kidney allograft recipients, its role in lung transplantation remains controversial. Therefore, we conducted a randomized, prospective, open-label, multicenter study in lung transplant recipients to determine whether MMF decreases episodes of acute allograft rejection when compared with azathioprine (AZA).

METHODS

Between March of 1997 and January of 1999, 81 consecutive lung transplant recipients from two centers were prospectively randomized to receive cyclosporine, corticosteroids, and either 2 mg/kg per day of AZA or 1 g twice daily of MMF. The primary study endpoint was biopsy-proven acute allograft rejection over the first 6 months posttransplant. Secondary endpoints included clinical rejection, cytomegalovirus (CMV) infection, adverse events, and survival. Surveillance bronchoscopies were performed at 1, 3, and 6 months, or if clinically indicated. Pathologists interpreting the biopsy results were blinded to the randomization. Results were analyzed according to intention-to-treat. Between group comparisons of means and proportions were made by using two sample t tests and Fisher's exact tests, respectively. Six-month survival was calculated by the Kaplan-Meier method and compared by the log rank test.

RESULTS

Thirty-eight patients were prospectively randomized to receive AZA, and 43 MMF. The incidence of biopsy proven grade II or greater acute allograft rejection at 6 months was 58% in the AZA group and 63% in the MMF group (P=0.82). The 6-month survival rates in the MMF and AZA groups were 86% and 82%, respectively (P=0.57). Rates of CMV infection and adverse events were not significantly different between the two groups.

CONCLUSIONS

Acute rejection rates and overall survival at 6 months are similar in lung transplant recipients treated with either MMF- or AZA-based immunosuppression.

Single lung transplantation from a brain-dead donor for a patient with idiopathic pulmonary fibrosis. A breakthrough after new legislation in Japan

Two single lung transplants from a single cadaveric donor were successfully conducted at 2 institutions on March 29, 2000, the first such procedure in Japan under newly introduced legislation. Our patient was a 48-year-old woman with idiopathic pulmonary fibrosis who underwent left single-lung transplantation under cardiopulmonary support. The donor lung was preserved in 4 degrees C modified Euro-Collins solution. Total ischemic time was 5 hours and 37 minutes. The postoperative course was uneventful. The patient was discharged on postoperative day 62 with satisfactory respiratory function.

Bone mineral density in lung-transplant recipients before and after graft: prevention of lumbar spine post-transplantation-accelerated bone loss by pamidronate

BACKGROUND

Lung-transplant recipients are at risk of osteoporosis. They may have low bone mass even before posttransplantation immunosuppressive therapy. We studied bone mineral density (BMD) before and after lung transplantation and compared the efficacy of antiresorptive therapies to calcium and vitamin D supplementation.

METHODS

Areal BMD was assessed in 42 patients awaiting lung transplantation and measured again after surgery at 6 (n = 29), and at 12 months (n = 20). Nineteen patients received antiresorptive therapy (30 mg pamidronate IV every 3 months (n = 14), or hormonal replacement therapy (n = 5)), and 10 patients received only calcium and vitamin D supplements.

RESULTS

Mean age- and gender-adjusted lumbar spine (LS) and femoral neck (FN) BMD was significantly decreased prior to transplantation (- 0.6 +/- 0.2, p< 0.01, and - 1.5 +/- 0.2 standard deviation, p < 0.001, respectively). At that time, 29% were osteoporotic (T-score < - 2.5 below the peak bone mass), while 55% were below - 1.0 T-score. Antiresorptive therapy decreased the rate of LS bone loss during the first 6 months and led to a significant increase of BMD at 1 year, with LS changes of + 0.2 +/- 0.1 vs - 0.4 +/- 0.1 Z-score in the calcium-vitamin D group (p< 0.002), and + 0.2 +/- 0.1 vs - 0.04 +/- 0.1 for FN (NS). One out of 20 patients experienced clinically evident fractures during antiresorptive therapy, and 3 out of 12 in the calcium-vitamin D group.

CONCLUSION

A significant proportion of patients awaiting lung transplantation was osteoporotic or osteopenic. Antiresorptive therapy (pamidronate or hormone-replacement therapy (HRT)) prevented accelerated LS bone loss after graft.

The use of mycophenolate mofetil in transplant recipients

With the development of new immunosuppressive agents, the focus of anti-rejection therapy has shifted from prevention of acute allograft rejection to an emphasis on sufficient immunosuppression with minimal toxicity. Mycophenolate mofetil (MMF) is a recently developed immunosuppressive drug, which acts to inhibit T and B cell proliferation by blocking the production of guanosine nucleotides required for DNA synthesis. It also prevents the glycosylation of adhesion molecules that are involved in attachment of lymphocytes to endothelium and potentially in leukocyte infiltration of an allograft during an immune response. High-quality randomized clinical trials have demonstrated that MMF, when used with cyclosporine (CsA) and steroids, reduces the frequency and severity of acute rejection episodes in kidney and heart transplants, improves patient and graft survival in heart allograft recipients and increases renal allograft survival at 3 years. It has also been effective in reversing acute and resistant rejection episodes in heart, kidney and liver recipients. The ability of MMF to facilitate sparing of other immunosuppressive agents, particularly in CsA-related nephrotoxicity, is also promising. By permitting reduction in CsA doses, MMF may stabilize or improve renal graft function in patients with CsA-related nephrotoxicity or chronic allograft nephropathy. Early results of phase I and II trials evaluating MMF therapy in liver and combined pancreas/kidney transplant recipients are encouraging. The main adverse effects associated with oral or intravenous MMF are gastrointestinal and hematologic in nature. Although the direct costs of using MMF vs. azathioprine (AZA) are higher, the decreased incidence and treatment of acute rejection in patients treated with MMF supports its use as a cost-effective option during the first year following transplantation.Thus, MMF has become an important therapeutic tool in the transplant clinician's armamentarium. Ongoing issues to be resolved in clinical trials include the role of MMF in the absence of other potent agents, e.g., as monotherapy or with a steroid but without calcineurin inhibitor; whether MMF will have an impact on chronic allograft dysfunction; and the cost-effectiveness of treatment following the first year of transplantation.

Overview of new immunosuppressive therapies

This review covers the new immunosuppressive drugs that have appeared in the past 5 years. It begins with the newest formulation (Neoral, Sandoz Pharmaceuticals, East Hanover, NJ, USA) of the clinically "mature" drug cyclosporin A and then reviews the literature on tacrolimus, sirolimus, and mycophenolate mofetil. In each case, the emphasis is on the evolution of experience with the drug and on the questions that the drug poses for pediatricians considering the risk-benefit ratio of the drug in children.