The incidence of acute cellular rejection after lung transplantation: a comparative study of anti-thymocyte globulin and daclizumab

Outcomes Following ATG Therapy for Chronic Lung Allograft Dysfunction

Chronic lung allograft dysfunction (CLAD) is the major factor limiting survival post lung transplantation (LTx) with limited effective therapeutic options. We report our 12-y experience of antithymocyte globulin (ATG) as second-line CLAD therapy.

Combined low-dose everolimus and low-dose tacrolimus after Alemtuzumab induction therapy: a randomized prospective trial in lung transplantation

Background

Long-term outcomes of lung transplantation are severely affected by comorbidities and development of chronic rejection. Among the comorbidities, kidney insufficiency is one of the most frequent and it is mainly caused by the cumulative effect of calcineurin inhibitors (CNIs). Currently, the most used immunosuppression protocols worldwide include induction therapy and a triple-drug maintenance immunosuppression, with one calcineurin inhibitor, one anti-proliferative drug, and steroids. Our center has pioneered the use of alemtuzumab as induction therapy, showing promising results in terms of short- and long-term outcomes. The use of alemtuzumab followed by a low-dose double drug maintenance immunosuppression, in fact, led to better kidney function along with excellent results in terms of acute rejection, chronic lung allograft dysfunction, and survival (Benazzo et al., PLoS One 14(1):e0210443, 2019). The hypothesis driving the proposed clinical trial is that de novo introduction of low-dose everolimus early after transplantation could further improve kidney function via a further reduction of tacrolimus. Based on evidences from kidney transplantation, moreover, alemtuzumab induction therapy followed by a low-dose everolimus and low-dose tacrolimus may have a permissive action on regulatory immune cells thus stimulating allograft acceptance.

Methods

A randomized prospective clinical trial has been set up to answer the research hypothesis. One hundred ten patients will be randomized in two groups. Treatment group will receive the new maintenance immunosuppression protocol based on low-dose tacrolimus and low-dose everolimus and the control group will receive our standard immunosuppression protocol. Both groups will receive alemtuzumab induction therapy. The primary endpoint of the study is to analyze the effect of the new low-dose immunosuppression protocol on kidney function in terms of eGFR change. The study will have a duration of 24 months from the time of randomization. Immunomodulatory status of the patients will be assessed with flow cytometry and gene expression analysis.

Discussion

For the first time in the field of lung transplantation, this trial proposes the combined use of significantly reduced tacrolimus and everolimus after alemtuzumab induction. The new protocol may have a twofold advantage: (1) further reduction of nephrotoxic tacrolimus and (2) permissive influence on regulatory cells development with further reduction of rejection episodes.

Trial registration

EUDRACT Nr 2018-001680-24. Registered on 15 May 2018

Ex-vivo delivery of monoclonal antibody (Rituximab) to treat human donor lungs prior to transplantation

Background

Ex-vivo lung perfusion (EVLP) is an innovative platform for assessing donor lungs in the pre-transplant window. In this study, we demonstrate an extension of its utility by administering the anti-CD20 monoclonal antibody, Rituximab, during EVLP. We hypothesized that this would lead to targeted depletion of allograft B-cells which may provide significant clinical benefit, including the potential to reduce latent Epstein-Barr virus (EBV) and decrease the incidence of post-transplant lymphoproliferative malignancies.

Methods

Twenty human donor lungs rejected for transplantation were placed on EVLP with (n = 10) or without (n = 10) 500 mg of Rituximab. Safety parameters such as lung physiology and inflammatory cytokines were evaluated. We measured the delivery efficacy through flow cytometry, immunohistochemistry and ELISA. An in-vitro culture assay, in the presence of complement, was further conducted to monitor whether B-cell depletion would occur in Rituximab-perfused samples.

Findings

Rituximab was successfully delivered to human lungs during EVLP as evidenced by flow cytometric binding assays where lung tissue and lymph node biopsies demonstrated occupied CD20 epitopes after perfusion with the antibody. Lymph nodes from Rituximab perfusions demonstrated a 10.9 fold-reduction in CD20+ staining compared to controls (p = 0.0003). In lung tissue, Rituximab resulted in an 8.75 fold-reduction in CD20+ staining relative to controls (p = 0.0002). This decrease in CD20+ binding illustrates the successful delivery and occupation of epitopes after perfusion with the Rituximab. No apparent safety concerns were seen as exhibited by markers associated with acute cell injury (e.g., proinflammatory cytokines), cell death (e.g., TUNEL staining), or pulmonary physiology. In a post-perfusion tissue culture model, the addition of complement (human serum) resulted in evidence of B-cell depletion consistent with what would be expected with posttransplant activation of bound Rituximab.

Interpretation

Our experiments illustrate the potential of EVLP as a platform to deliver monoclonal antibody therapies to treat donor lungs pretransplant with the goal of eliminating a latent virus responsible for considerable morbidity after lung transplantation.

Funding

Supported by the University Health Network Transplant Center.

Developments in lung transplantation over the past decade

With an improved median survival of 6.2 years, lung transplantation has become an increasingly acceptable treatment option for end-stage lung disease. Besides survival benefit, improvement of quality of life is achieved in the vast majority of patients. Many developments have taken place in the field of lung transplantation over the past decade. Broadened indication criteria and bridging techniques for patients awaiting lung transplantation have led to increased waiting lists and changes in allocation schemes worldwide. Moreover, the use of previously unacceptable donor lungs for lung transplantation has increased, with donations from donors after cardiac death, donors with increasing age and donors with positive smoking status extending the donor pool substantially. Use of ex vivo lung perfusion further increased the number of lungs suitable for lung transplantation. Nonetheless, the use of these previously unacceptable lungs did not have detrimental effects on survival and long-term graft outcomes, and has decreased waiting list mortality. To further improve long-term outcomes, strategies have been proposed to modify chronic lung allograft dysfunction progression and minimise toxic immunosuppressive effects. This review summarises the developments in clinical lung transplantation over the past decade.

Many developments have taken place in lung transplantation over the last decade: indications have broadened, donor criteria expanded, allocations systems changed, and novel therapeutic interventions implemented, leading to improved long-term survivalhttp://bit.ly/2vnpwc1

Early Tacrolimus Concentrations After Lung Transplant Are Predicted by Combined Clinical and Genetic Factors and Associated With Acute Kidney Injury

Tacrolimus exhibits unpredictable pharmacokinetics (PKs) after lung transplant, partly explained by cytochrome P450 (CYP)-enzyme polymorphisms. However, whether exposure variability during the immediate postoperative period affects outcomes is unknown, and pharmacogenetic dosing may be limited by residual PK variability. We estimated adjusted associations between early postoperative tacrolimus concentrations and acute kidney injury (AKI) and acute cellular rejection (ACR), and identified clinical and pharmacogenetic factors that explain postoperative tacrolimus concentration variability in 484 lung transplant patients. Increasing tacrolimus concentration was associated with higher AKI risk (hazard ratio (HR) 1.54; 95% confidence interval (CI) 1.20-1.96 per 5-mg/dL); and increasing AKI severity (odds ratio 1.29; 95% CI 1.04-1.60 per 5-mg/dL), but not ACR (HR 1.02; 95% CI 0.73-1.42). A model with clinical and pharmacogenetic factors explained 42% of concentration variance compared with 19% for pharmacogenetic factors only. Early tacrolimus exposure was independently associated with AKI after lung transplantation, but not ACR. Clinical factors accounted for substantial residual tacrolimus concentration variability not explained by CYP-enzyme polymorphisms.

Alemtuzumab induction combined with reduced maintenance immunosuppression is associated with improved outcomes after lung transplantation: A single centre experience

Question addressed by the study

The value of induction therapy in lung transplantation is controversial. According to the ISHLT, only about 50% of patients transplanted within the last 10 years received induction therapy. We reviewed our institutional experience to investigate the impact of induction therapy on short- and long-term outcomes.

Materials/Patients and methods

Between 2007 and 2015, 446 patients with a complete follow-up were included in this retrospective analysis. Analysis comprised long-term kidney function, infectious complications, incidence of rejection and overall survival.

Results

A total of 231 patients received alemtuzumab, 50 patients antithymocyte globulin (ATG) and 165 patients did not receive induction therapy (NI). The alemtuzumab group revealed the lowest rate of chronic kidney insufficiency (NI: 52.2%; ATG: 60%; alemtuzumab: 36.6%; p = 0.001). Both, the NI group (p<0.001) and the ATG group (p = 0.010) showed a significant increase of serum creatinine during follow-up compared to alemtuzumab patients. Furthermore, alemtuzumab group experienced the lowest rate of infection in the first year after transplantation. Finally, improved survival, low rates of acute cellular rejection (ACR), lymphocytic bronchiolitis (LB) and chronic lung allograft dysfunction (CLAD) were found in patients treated either with alemtuzumab or ATG.

Conclusion

Alemtuzumab induction therapy followed by reduced maintenance immunosuppression is associated with a better kidney function compared to no induction and ATG. Survival rate as well as freedom from ACR and CLAD were comparable between alemtuzumab and ATG.

Historical perspectives of lung transplantation: connecting the dots

Lung transplantation is now a treatment option for many patients with end-stage lung disease. Now 55 years since the first human lung transplant, this is a good time to reflect upon the history of lung transplantation, to recognize major milestones in the field, and to learn from others' unsuccessful transplant experiences. James Hardy was instrumental in developing experimental thoracic transplantation, performing the first human lung transplant in 1963. George Magovern and Adolph Yates carried out the second human lung transplant a few days later. With a combined survival of only 26 days for these first 2 lung transplant recipients, the specialty of lung transplantation clearly had a long way to go. The first "successful" lung transplant, in which the recipient survived for 10.5 months, was reported by Fritz Derom in 1971. Ten years later, Bruce Reitz and colleagues performed the first successful en bloc transplantation of the heart and one lung with a single distal tracheal anastomosis. In 1988, Alexander Patterson performed the first successful double lung transplant. The modern technique of sequential double lung transplantation and anastomosis performed at the mainstem bronchus level was originally described by Henri Metras in 1950, but was not reintroduced into the field until Pasque reported it again in 1990. Since then, lung transplantation has seen landmark changes: evolving immunosuppression regimens, clarifying the definition of primary graft dysfunction (PGD), establishing the lung allocation score (LAS), introducing extracorporeal membrane oxygenation (ECMO) as a bridge to transplant, allowing donation after cardiac death, and implementing ex vivo perfusion, to name a few. This article attempts to connect the historical dots in this field of research, with the hope that our effort helps summarize what has been achieved, and identifies opportunities for future generations of transplant pulmonologists and surgeons alike.

Increasing tacrolimus time-in-therapeutic range is associated with superior one-year outcomes in lung transplant recipients

Calcineurin inhibitors (CNIs) are the backbone of traditional immunosuppressive regimens for lung transplant recipients (LTR). The CNIs are both narrow therapeutic index drugs with significant interpatient and intrapatient variability that require therapeutic drug monitoring to ensure safety and effectiveness. We hypothesized that tacrolimus time-in-therapeutic range (TTR) affects acute and chronic rejection rates in LTRs. This was a single-center, observational, cross-sectional study of 292 adult LTRs. Subjects who received tacrolimus posttransplant for the first year were included. TTR was calculated at 1 year using protocol goal ranges (12-15 mg/mL months 0-6; 10-12 mg/mL for months 7-12). The primary outcome was acute cellular rejection (ACR) burden at 1 year. Chronic lung allograft dysfunction (CLAD), mortality, and infection rate were assessed as secondary outcomes at 1 year. Primary and secondary outcomes were assessed using logistic regression. Increasing TTR by 10% was associated with a significantly lower likelihood of high-burden ACR at 1 year on univariable (OR 0.46, 95% CI 0.40-0.54, P < .001) and multivariable (OR 0.64, 95% CI 0.47-0.86, P = .003) assessment, controlling for age and induction agent. Increasing TTR by 10% was also associated with lower rates of CLAD (P < .001) and mortality (P < .001) at 1 year. Prospective studies confirming these findings appear warranted.

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.

Combined Heart Lung Transplantation: An Updated Review of the Current Literature

Heart lung transplantation is a viable treatment option for patients with many end-stage heart and lung pathologies. However, given the complex nature of the procedure, it is imperative that patients are selected appropriately, and the clinician is aware of the many unique aspects in management of this population. This review seeks to describe updated organ selection policies, perioperative and postoperative management strategies, monitoring of graft function, and clinical outcomes for patients after combined heart-lung transplantation in the current era.

Acute Rejection and Antibody-Mediated Rejection in Lung Transplantation

Despite advances in immunosuppression over the past 25 years, acute cellular rejection remains a common complication early after lung transplantation. Although acute cellular rejection has often not resulted in clinical signs or symptoms of allograft dysfunction, it has been widely recognized as a strong independent risk factor for the development of chronic rejection, emphasizing its clinical significance. In recent years, the role of humoral immunity in lung rejection has been increasingly appreciated, and antibody-mediated rejection is now recognized as a form of rejection that may result in allograft failure.

Future direction of immunosuppression in lung transplantation

PURPOSE OF REVIEW

Immunosuppression regimens have helped improve rejection episodes following lung transplantation, but long-term outcomes are still not comparable with cardiac, hepatic, or renal transplantation. This review summarizes the immunobiology that contributes to rejection events and future opportunities in outcomes on the basis of providing optimized delivery of the immunosuppression based on immune-monitoring techniques, taking into account individual patient pharmacokinetics and phenotypic variance.

RECENT FINDINGS

Drug toxicities, narrow therapeutic drug monitoring windows, and current immunoassays currently do not assist in detecting the global degree of immunosuppression. The currently available randomized control trials for induction therapy or maintenance therapies do not provide additional benefits compared with previously reported retrospective trials. To push beyond the current barriers, transplant teams are focusing on the role of pharmacokinetics, assessing phenotypic variable to potentially modify to quadruple therapy and using extracorporeal photopheresis.

SUMMARY

Conventional practice for the choices of immunosuppression is being evaluated on the basis of randomized control trials as opposed to retrospective studies or single-center trials. The future direction of immunosuppression will be continued by dynamic processes taking into consideration measures to improve tolerance, reducing treatment burden, and providing the best level of evidence while accounting for rejection, infections, renal function, and other comorbidities.

Immunosuppression in lung transplantation

Lung transplantation can be a life-saving procedure for those with end-stage lung diseases. Unfortunately, long term graft and patient survival are limited by both acute and chronic allograft rejection, with a median survival of just over 6 years. Immunosuppressive regimens are employed to reduce the rate of rejection, and while protocols vary from center to center, conventional maintenance therapy consists of triple drug therapy with a calcineurin inhibitor (cyclosporine or tacrolimus), antiproliferative agents [azathioprine (AZA), mycophenolate, sirolimus (srl), everolimus (evl)], and corticosteroids (CS). Roughly 50% of lung transplant centers also utilize induction therapy, with polyclonal antibody preparations [equine or rabbit anti-thymocyte globulin (ATG)], interleukin 2 receptor antagonists (IL2RAs) (daclizumab or basiliximab), or alemtuzumab. This review summarizes these agents and the data surrounding their use in lung transplantation, as well as additional common and novel therapies in lung transplantation. Despite the progression of the management of lung transplant recipients, they continue to be at high risk of treatment-related complications, and poor graft and patient survival. Randomized clinical trials are needed to allow for the development of better agents, regimens and techniques to address above mentioned issues and reduce morbidity and mortality among lung transplant recipients.

Immunosuppression and allograft rejection following lung transplantation: evidence to date

The enduring success of lung transplantation is built on the use of immunosuppressive drugs to stop the immune system from rejecting the newly transplanted lung allograft. Most patients receive a triple-drug maintenance immunosuppressive regimen consisting of a calcineurin inhibitor, an antiproliferative and corticosteroids. Induction therapy with either an antilymphocyte monoclonal or an interleukin-2 receptor antagonist are prescribed by many centres aiming to achieve rapid inhibition of recently activated and potentially alloreactive T lymphocytes. Despite this generic approach acute rejection episodes remain common, mandating further fine-tuning and augmentation of the immunosuppressive regimen. While there has been a trend away from cyclosporine and azathioprine towards a preference for tacrolimus and mycophenolate mofetil, this has not translated into significant protection from the development of chronic lung allograft dysfunction, the main barrier to the long-term success of lung transplantation. This article reviews the problem of lung allograft rejection and the evidence for immunosuppressive regimens used both in the short- and long-term in patients undergoing lung transplantation.

Antibody induction therapy for lung transplant recipients

BACKGROUND

Lung transplantation has become a valuable and well-accepted treatment option for most end-stage lung diseases. Lung transplant recipients are at risk of transplanted organ rejection, and life-long immunosuppression is necessary. Clear evidence is essential to identify an optimal, safe and effective immunosuppressive treatment strategy for lung transplant recipients. Consensus has not yet been achieved concerning use of immunosuppressive antibodies against T-cells for induction following lung transplantation.

OBJECTIVES

We aimed to assess the benefits and harms of immunosuppressive T-cell antibody induction with ATG, ALG, IL-2RA, alemtuzumab, or muromonab-CD3 for lung transplant recipients.

SEARCH METHODS

We searched the Cochrane Renal Group's Specialised Register to 4 March 2013 through contact with the Trials Search Co-ordinator using search terms relevant to this review. Studies contained in the Specialised Register are identified through search strategies specifically designed for CENTRAL, MEDLINE and EMBASE.

SELECTION CRITERIA

We included all randomised controlled trials (RCTs) that compared immunosuppressive monoclonal and polyclonal T-cell antibody induction for lung transplant recipients. An inclusion criterion was that all participants must have received the same maintenance immunosuppressive therapy within each study.

DATA COLLECTION AND ANALYSIS

Three authors extracted data. We derived risk ratios (RR) for dichotomous data and mean differences (MD) for continuous data with 95% confidence intervals (CI). Methodological risk of bias was assessed using the Cochrane risk of bias tool and trial sequential analyses were undertaken to assess the risk of random errors (play of chance).

MAIN RESULTS

Our review included six RCTs (representing a total of 278 adult lung transplant recipients) that assessed the use of T-cell antibody induction. Evaluation of the included studies found all to be at high risk of bias.We conducted comparisons of polyclonal or monoclonal T-cell antibody induction versus no induction (3 studies, 140 participants); polyclonal T-cell antibody versus no induction (3 studies, 125 participants); interleukin-2 receptor antagonists (IL-2RA) versus no induction (1 study, 25 participants); polyclonal T-cell antibody versus muromonab-CD3 (1 study, 64 participants); and polyclonal T-cell antibody versus IL-2RA (3 studies, 100 participants). Overall we found no significant differences among interventions in terms of mortality, acute rejection, adverse effects, infection, pneumonia, cytomegalovirus infection, bronchiolitis obliterans syndrome, post-transplantation lymphoproliferative disease, or cancer.We found a significant outcome difference in one study that compared antithymocyte globulin versus muromonab-CD3 relating to adverse events (25/34 (74%) versus 12/30 (40%); RR 1.84, 95% CI 1.13 to 2.98). This suggested that antithymocyte globulin increased occurrence of adverse events. However, trial sequential analysis found that the required information size had not been reached, and the cumulative Z-curve did not cross the trial sequential alpha-spending monitoring boundaries.None of the studies reported quality of life or kidney injury. Trial sequential analyses indicated that none of the meta-analyses achieved required information sizes and the cumulative Z-curves did not cross the trial sequential alpha-spending monitoring boundaries, nor reached the area of futility.

AUTHORS' CONCLUSIONS

No clear benefits or harms associated with the use of T-cell antibody induction compared with no induction, or when different types of T-cell antibodies were compared were identified in this review. Few studies were identified that investigated use of antibodies against T-cells for induction after lung transplantation, and numbers of participants and outcomes were also limited. Assessment of the included studies found that all were at high risk of methodological bias.Further RCTs are needed to perform robust assessment of the benefits and harms of T-cell antibody induction for lung transplant recipients. Future studies should be designed and conducted according to methodologies to reduce risks of systematic error (bias) and random error (play of chance).

Monitoring of nonsteroidal immunosuppressive drugs in patients with lung disease and lung transplant recipients: American College of Chest Physicians evidence-based clinical practice guidelines

OBJECTIVES

Immunosuppressive pharmacologic agents prescribed to patients with diffuse interstitial and inflammatory lung disease and lung transplant recipients are associated with potential risks for adverse reactions. Strategies for minimizing such risks include administering these drugs according to established, safe protocols; monitoring to detect manifestations of toxicity; and patient education. Hence, an evidence-based guideline for physicians can improve safety and optimize the likelihood of a successful outcome. To maximize the likelihood that these agents will be used safely, the American College of Chest Physicians established a committee to examine the clinical evidence for the administration and monitoring of immunosuppressive drugs (with the exception of corticosteroids) to identify associated toxicities associated with each drug and appropriate protocols for monitoring these agents.

METHODS

Committee members developed and refined a series of questions about toxicities of immunosuppressives and current approaches to administration and monitoring. A systematic review was carried out by the American College of Chest Physicians. Committee members were supplied with this information and created this evidence-based guideline.

CONCLUSIONS

It is hoped that these guidelines will improve patient safety when immunosuppressive drugs are given to lung transplant recipients and to patients with diffuse interstitial lung disease.

Lung transplant

The ICU period is only one time point among many in the complex, multidisciplinary postoperative management required for patient survival and improved QOL. The care required on step-down units and after discharge to home each has unique care aspects that impact successful patient outcomes.

Radiological patterns of primary graft dysfunction after lung transplantation evaluated by 64-multi-slice computed tomography: a descriptive study

We evaluated the diagnostic value of high-resolution computed tomography (HRCT) images generated from 64 detector multi-slice CT scanners (HRCT(64-MSCT) imaging) in relation to primary graft dysfunction (PGD) after lung-transplantation (LUTX) in a pilot study. PGD has mortality rates ranging from 17 to 50% over a 90-day period. Detailed HRCT lung images, reconstructed using 64-MSCT, may aid diagnostic and therapeutic efforts in PGD. Thirty-two patients were scanned four times within a year post-LUTX, in a single-centre prospective study. HRCT lung images were reviewed, evaluated and scored by two observers, for ground-glass (GG) opacities, consolidation, septal thickening (ST) and pulmonary embolism. Image and PGD scores were compared in each patient. GG and consolidation changes were largely present up until 2 weeks post-LUTX, and markedly reduced by the 12th week. ST was predominantly found in patients with PGD. There were no vascular changes found at CT angiographies. The most severe cases of GG opacities and consolidation were found in patients with PGD. ST seems to be an important indicator of PGD. HRCT(64-MSCT) imaging may be a useful tool for the identification of pathological features of PGD not detected by classical evaluation in patients undergoing LUTX.

Conventional and novel approaches to immunosuppression

Immunosuppressive therapy has contributed significantly to improved survival after solid organ transplantation. Nevertheless, treatment-related adverse events and persistently high risk of chronic graft rejection remain major obstacles to long-term survival after lung transplantation. The development of new agents, refinements in techniques to monitor immunosuppression, and enhanced understanding of transplant immunobiology are essential for further improvements in outcome. In this article, conventional immunosuppressive regimens, novel approaches to preventing graft rejection, and investigational agents for solid organ transplantation are reviewed.

Timing of basiliximab induction and development of acute rejection in lung transplant patients

BACKGROUND

Acute rejection affects more than 36% of recipients within the first year post-transplantation. The interleukin-2 (IL-2) receptor antagonist basiliximab has been associated with decreased frequency and severity of acute rejection. We investigated whether the timing of induction administration would impact the frequency and severity of acute rejection in the first year after transplantation.

METHODS

In this study we reviewed 119 patients who underwent lung transplantation at Henry Ford Hospital from October 1994 to January 2009. Prior to January 2000 no patients received induction. From January 2000 to March 2006 the initial dose was given after implantation, and from March 2006 to 2009 basiliximab was given prior to implantation. The primary outcome was cumulative acute rejection score (CAR) in the first post-operative year comparing post- vs pre-implant induction.

RESULTS

The CAR score for pre-implant basiliximab was 2.5 ± 2.3. This was significantly lower than CAR score of 4.6 ± 3.9 in the post-implant group (p = 0.025). The no-induction group had the highest CAR score at 6.3 ± 3.8 (p = 0.077 compared with the post group). The mean follow-up times in the post and pre group were 5.9 ± 2.3 and 2.3 ± 0.7 years, respectively (p < 0.001). There was no difference in freedom from bronchiolitis obliterans syndrome (BOS), survival or invasive infections between pre- and post-implant induction groups.

CONCLUSIONS

Basiliximab prior to implant is associated with a lower cumulative acute rejection score over 1 year compared with induction post-implantation. Despite a lower cumulative acute rejection score, there was no significant difference in freedom from BOS or survival.

Induction therapy: why, when, and which agent?

The long-term outcome of paediatric transplantation has improved over the last decade with an increase in the armamentarium of immunosuppressive agents. However, the battle against the hostile immune response at the time of and after transplantation continues. Induction therapy can reduce early injury, to optimize the long-term allograft survival. The goal of induction immunosuppression in paediatric transplantation is to permit the use of lower doses of maintenance immunosuppressive agents without increased rates of acute allograft rejection and chronic allograft damage. The aim of this review is to summarize the current literature relating to the use of antibody agents for induction in paediatric solid organ transplantation.

Acute cellular rejection is a risk factor for bronchiolitis obliterans syndrome independent of post-transplant baseline FEV1

BACKGROUND

Post-transplant baseline forced expiratory volume in 1 second (FEV(1)) constitutes a systematic bias in analyses of bronchiolitis obliterans syndrome (BOS). This retrospective study evaluates risk factors for BOS adjusting for the confounding of post-transplant baseline FEV(1).

METHODS

A multivariate survival and competing risk analysis of a large consecutive series of patients (n = 389) from a national center 1992 to 2004. Exclusion criteria were patients not surviving at least 3 months after transplantation (n = 39) and no available lung function measurements (n = 4).

RESULTS

The first maximum FEV(1) occurred at a median 183 days post-transplant. Freedom from BOS was 81%, 53%, 38% and 15%, and cumulative incidence of BOS was 18%, 43%, 57% and 77% at 1, 3, 5 and 10 years post-transplantation, respectively. Acute cellular rejection was independently associated with an increased cause-specific hazard of BOS (hazard ratio 1.4, confidence interval 1.1 to 1.8, p = 0.009). The absolute value of baseline FEV(1) was a significant confounder in all survival and competing risk analyses of BOS (p < 0.05).

CONCLUSION

Despite early diagnosis and prompt treatment, acute cellular rejection remains an independent risk factor for the development of BOS after adjusting for the confounding of post-transplant baseline FEV(1).

Management of the patient undergoing lung transplantation: an intensive care perspective

The postoperative management of a patient undergoing lung transplantation involves many components of care. These components include ventilatory and hemodynamic management, immunosuppression, wound care, rehabilitation, infection control and treatment, and early detection of rejection.

Immunosuppression for lung transplantation

As a result of advances in surgical techniques, immunosuppressive therapy, and postoperative management, lung transplantation has become an established therapeutic option for individuals with a variety of end-stage lung diseases. The current 1-year actuarial survival rate following lung transplantation is approaching 80%. However, the 5- year actuarial survival rate has remained virtually unchanged at approximately 50% over the last 15 years due to the processes of acute and chronic lung allograft rejection (1). Clinicians still rely on a vast array of immunosuppressive agents to suppress the process of graft rejection, but find themselves limited by an inescapable therapeutic paradox. Insufficient immunosuppression results in graft loss due to rejection, while excess immunosuppression results in increased morbidity and mortality from opportunistic infections and malignancies. Indeed, graft rejection, infection, and malignancy are the three principal causes of mortality for the lung transplant recipient. One should also keep in mind that graft loss in a lung transplant recipient is usually a fatal event, since there is no practical means of long-term mechanical support, and since the prospects of re-transplantation are low, given the shortage of acceptable donor grafts. This chapter reviews the current state of immunosuppressive therapy for lung transplantation and suggests alternative paradigms for the management of future lung transplant recipients.

Interstitial inflammatory lesions of the pulmonary allograft: a retrospective analysis of 2697 transbronchial biopsies

BACKGROUND

Parenchymal and bronchial inflammatory and fibrotic lesions other than acute cellular rejection (ACR) and lymphocytic bronchiolitis are prevalent; however, the context in which they appear is unknown, and often no specific treatment is instigated.

OBJECTIVES

To describe the prevalence, incidence and possible associations between commonly identified inflammatory and fibrotic lesions in the pulmonary allograft.

METHODS

Retrospective chart review of all transbronchial biopsies performed within the first 2 years of 299 lung-transplanted patients in the period 1996 to 2006.

RESULTS

A total of 2697 biopsies were evaluated corresponding to a mean of 6+/-2 (median 8) completed schedules per patient. Diffuse alveolar damage (DAD) was the second most common histological finding within the first 2 weeks after transplantation. The peak prevalence of bronchiolitis obliterans organizing pneumonia (BOOP) and interstitial pneumonitis occurred at 4 to 6 weeks, and 6 to 12 weeks, respectively. There was a steady increase in the cumulative proportion of patients with fibrosis and bronchiolitis obliterans, at each successive scheduled surveillance time point beyond 3 months posttransplantation. The strongest histological correlations were between ACR and lymphocytic bronchiolitis (OR 5.1, P<0.0001) or interstitial fibrosis (OR 3.2, P<0.0001). Patients with interstitial pneumonitis and pulmonary hemosiderosis were also more likely to demonstrate the finding of interstitial fibrosis (OR 3.0 and 3.7, P<0.0001, respectively). Acute cellular rejection was not associated with DAD, and patients with lymphocytic bronchiolitis were not more likely to demonstrate features of organizing pneumonia (DAD or BOOP).

CONCLUSIONS

Histologic findings of ACR, lymphocytic bronchiolitis, BOOP, and interstitial pneumonitis were directly associated with the development of interstitial fibrosis and bronchiolitis obliterans.

Effects of induction immunosuppression regimen on acute rejection, bronchiolitis obliterans, and survival after lung transplantation

OBJECTIVE

Effects of daclizumab and antithymocyte globulin induction on acute rejection, bronchiolitis obliterans syndrome, and survival after lung transplantation are unknown. We hypothesized that daclizumab results in less acute rejection and bronchiolitis obliterans and better survival than antithymocyte globulin.

METHODS

Consecutive adult lung transplants (n = 163) at the University of Virginia from January 1998 to May 2006 were reviewed. Antithymocyte globulin induction was routinely performed before January 2002 (65 patients), after which all patients received daclizumab (98 patients). Estimates of cumulative event rate of acute rejection, bronchiolitis obliterans, and death were calculated by Kaplan-Meier method and between-group differences compared by log-rank test. Cox proportional hazards models were fitted to assess treatment effects adjusted for covariates.

RESULTS

Groups were similar in demographics and preoperative and intraoperative risk factors. Maintenance immunosuppression changed during the study, and mycophenolate mofetil was more commonly given to patients receiving daclizumab. By Kaplan-Meier method, daclizumab was associated with significantly less acute rejection (P = .002), less bronchiolitis obliterans (P = .02), and improved overall survival (P = .04). Induction agent was highly associated with acute rejection (P = .002), bronchiolitis obliterans (P = .02), and mortality (P = .05); antimetabolite agent was associated only with acute rejection (P = .01). Adjusting for covariates, induction agent remained significantly predictive for acute rejection (P = .02) and bronchiolitis obliterans (P = .05), approaching significance for survival (P = .07).

CONCLUSION

Lung transplant recipients receiving daclizumab for induction had significantly less acute rejection and bronchiolitis obliterans than those receiving antithymocyte globulin, with possibly improved survival. Improvements in acute rejection may have been confounded by the use of mycophenolate mofetil.

Aspergillus infection in lung transplant patients: incidence and prognosis

Lung transplant recipients experience a particularly high incidence of Aspergillus infection in comparison with other solid-organ transplantations. This study was conducted to determine the incidence of Aspergillus colonisation and invasive aspergillosis, and the impact on long-term survival associated with Aspergillus infection. A retrospective study of 362 consecutive lung transplant patients from a single national centre who were transplanted 1992-2003 were studied. Twenty-seven patients were excluded due to incomplete or missing files. A total of 105/335 (31%) patients had evidence of Aspergillus infection (colonisation or invasion), including 83 (25%) patients with colonisation and 22 (6%) patients with radiographic or histological evidence of invasive disease. Most of the infections occurred within the first 3 months after transplantation. Cystic fibrosis (CF) patients had higher incidences of colonisation and invasive disease [15 (42%) and 4 (11%) of 36 patients] than non-CF patients [68 (23%) and 18 (6%) of 299 patients] (P = 0.01). Invasive aspergillosis was associated with 58% mortality after 2 years, whereas colonisation was not associated with early increased mortality but was associated with increased mortality after 5 years compared to non-infected patients (P < 0.05). An analysis of demographic factors showed that donor age [OR 1.40 per decade (95% CI 1.10-1.80)], ischaemia time [OR 1.17 per hour increase (95% CI 1.01-1.39)], and use of daclizumab versus polyclonal induction [OR 2.05 (95% CI 1.14-3.75)] were independent risk factors for Aspergillus infection. Invasive aspergillosis was associated with early and high mortality in lung transplant patients. Colonisation with Aspergillus was also associated with a significant increase in mortality after 5 years. CF patients have a higher incidence of Aspergillus infection than non-CF patients.

A randomized controlled trial of tacrolimus versus cyclosporine after lung transplantation

BACKGROUND

The optimal maintenance immunosuppressive regimen after lung transplantation is uncertain.

METHODS

We conducted a randomized controlled trial of tacrolimus versus cyclosporine in combination with azathioprine and prednisone after lung transplantation. Ninety adults were randomized to tacrolimus (n = 44) or cyclosporine (n = 46). The primary end point was a composite of a cumulative acute rejection A score of 3 or higher, a cumulative lymphocytic bronchitis B score of 4 or higher, or the onset of bronchiolitis obliterans syndrome (BOS) stage 0-p.

RESULTS

Recipients randomized to cyclosporine were significantly more likely to develop the primary end point than those randomized to tacrolimus. During the study period, the primary end point developed in 39 of 46 cyclosporine subjects compared with 24 of 44 tacrolimus subjects (p = 0.002); acute rejection or lymphocytic bronchitis end points developed in 29 of 46 cyclosporine subjects compared with 18 of 44 tacrolimus subjects (p = 0.036). Furthermore, BOS stage 0-p was more likely to develop in the cyclosporine group than in the tacrolimus group, but this was not statistically significant (log-rank p = 0.1). In addition, there was a trend to a higher incidence of diabetes among those in the tacrolimus group, but there was no significant difference in graft survival or the total number of infections, or in the incidence of hypertension, chronic kidney disease, or cancer between the 2 groups.

CONCLUSIONS

Tacrolimus is associated with a lower burden of acute rejection and lymphocytic bronchitis and a trend to a greater freedom from BOS stage 0-p than cyclosporine after lung transplantation.

Daclizumab

Daclizumab is a humanized monoclonal antibody which binds to the IL-2 receptor on activated lymphocytes and blocks the production of IL-2. Its use is well established in solid organ transplantation as induction therapy, especially in high-risk patients where reduction or delayed dose of standard immunosuppression would be beneficial. It has been used effectively in both 2-dose and 5-dose regimens in conjunction with other standard immunosuppressive agents. The incidence of acute rejection appears reduced without increasing the rates of infection or post-transplant lympho-proliferative disorders. The agent is generally well tolerated in adults and children and there is no need for additional monitoring. Daclizumab has also been used outside the transplant arena in a variety of immune-mediated diseases with limited success.

The future of antibody therapy

Antibodies have been used successfully as therapeutics for over 100 years. The successful development of therapeutic human(ized) monoclonal antibodies (mAbs) in the last 20 years has demonstrated the potency of mAbs but also revealed some of their limitations. Studies in animals and humans demonstrated that it is possible to overcome some of these limitations using mixtures of mAbs or polyclonal antibody (pAb) preparations. pAbs from human and animal plasma are efficacious and safe therapeutics for the treatment of many diseases. Novel technologies are being developed for the production of human pAbs in genetically engineered animals. Immunization of such animals should allow the production of effective and safe high-titer antibody preparations for the treatment of infectious diseases, cancer, and autoimmunity.

Long-term Survival After Lung Transplantation Depends on Development and Severity of Bronchiolitis Obliterans Syndrome

BACKGROUND

The objectives of this study were to describe the natural history of bronchiolitis obliterans syndrome (BOS) in a large consecutive series of patients from a national center in accordance with the most recent grading criteria, and to examine the prognosis with respect to onset and severity of BOS.

METHODS

All patients receiving a cadaveric lung transplant between 1992 and 2004 were included in the study (n = 389). Exclusion criteria were patients not surviving at least 3 months after transplantation (n = 39) and lack of available lung function measurements (n = 4).

RESULTS

The 1-, 3-, 5- and 10-year actuarial survival rates for the entire series were 81%, 67%, 60% and 36%, respectively. The 1-, 3-, 5- and 10-year actuarial freedom from BOS Grade > or = 1 was 81%, 53%, 38% and 15%, respectively. A Cox regression model with BOS grade as a time-dependent covariate was performed in a sub-group of patients surviving at least 3 years (n = 237). Both progression from BOS Grade 1 to 2 and from BOS Grade 2 to 3 were associated with a significant increase in mortality: hazard ratio (HR) = 3.1 (confidence interval [CI] 1.2 to 7.9) and HR = 2.9 (CI 1.6 to 5.3), respectively. The addition of a non-time-dependent covariate to signify early (within 18 months of transplantation) or late (after 18 months) development of BOS was not significant (p = 0.5).

CONCLUSIONS

The development and progression of chronic allograft rejection after lung transplantation (BOS Grades 2 and 3) is associated with a 3-fold increase in the risk of death at each stage, irrespective of whether BOS developed early or late.

Emerging drugs in lung transplantation

The balance between immunosuppression to ensure graft tolerance while preventing emergence of infectious complications is key in lung transplantation. Although opportunistic infection may appear to be the most important of these complications, malignancies and severe drug toxicities significantly affect the short- and long-term outcomes of the patients. The present practice is combination therapy using drugs with complementary immunosuppressive action, to achieve synergistic immunosuppression with the lowest possible toxicity. Components of immunosuppression include induction and maintenance regimens. Primary graft failure remains an important cause of mortality and morbidity in the immediate post-transplant period. Acute rejection is a common complication after lung transplant, but responds well to augmented immunosuppression and immunomodulation. Chronic rejection still is the major cause of mortality in patients who survive the initial year post-transplantation. Several new drugs have shown promise in decreasing the rate of loss of graft function. This review discusses the current and emerging therapeutic regimens.

A randomized, controlled trial of daclizumab vs anti-thymocyte globulin induction for lung transplantation

BACKGROUND

Rejection remains a significant cause of morbidity and mortality after lung transplantation. The purpose of this study was to test the efficacy and safety of daclizumab (DZM) vs anti-thymocyte globulin (ATG) as a component of induction therapy.

METHODS

Fifty adults undergoing lung transplantation were randomized to receive either ATG or DZM during induction therapy. Patients were followed for 1 year after transplant.

RESULTS

Although there was no significant difference in the number of acute or chronic rejections between groups, there was a trend toward a delay in time to first acute rejection with DZM induction. Average absolute lymphocytes and average platelet count were significantly higher in the DZM group. Cytomegalovirus (CMV) serology mismatch was higher in the DZM group (7 vs 1, p = 0.05). The DZM group had a greater number of infections (83 vs 47, p = 0.02); however, the number of CMV infections was also significantly greater (18 vs 6, p = 0.03), corresponding to a higher incidence of CMV mismatch. A cost analysis revealed no difference between total drug costs, intensive-care unit (ICU) costs and total hospital costs. One-year survival was 96% in the DZM group and 88% in the ATG group.

CONCLUSIONS

DZM is a safe component of induction therapy in lung transplantation. In addition, DZM may prolong freedom from acute rejection. Significant infections were more frequent in the DZM group, but this was likely due to a higher incidence of CMV mismatch. Both methods of induction therapy worked well, with excellent 1-year survival.

Immunosuppression in pediatric solid organ transplantation: opportunities, risks, and management

The pediatric transplant community stands at a time of unprecedented choice of immunosuppressive agents - and with a legacy of morbidity from those agents used in the previous two decades. This review considers the clinical utility and side-effect profiles of immunosuppressants used widely in current practice (e.g., glucocorticoids, azathioprine, ciclosporin, tacrolimus, mycophenolate, and sirolimus) and those agents which are in increasing use or in evaluation (e.g., IL-2 receptor antibodies, everolimus, FTY720, LEA29Y, and deoxyspergualin). Further consideration is given to the wider drug interactions likely during the use of new immunosuppressant regimens and to our growing awareness of the influences of genetic heterogeneity on drug efficacy and handling. Finally, we consider the new demands being placed on the use of drug monitoring to regulate dosage of this new repertoire of immunosuppressants.