Low rate of acute lung allograft rejection after the use of daclizumab, an interleukin 2 receptor antibody

Basiliximab vs. Antithymocyte Globulin as Initial Induction Therapy for Lung Transplantation: A National Two Years Review

Basiliximab (BAS) is an interleukin-2 monoclonal antibody initially used as induction therapy after liver and kidney transplantation. BAS use after lung transplantation (LTx) has supplanted antithymocyte globulin (ATG) as the main induction immunosuppression over the years, but few studies have compared them. In this study, we aimed to compare the efficacy and safety between BAS and ATG in LTx. We performed a retrospective analysis of all LTx done in Portugal between January 2016 and December 2019. Three groups were made according to the initial induction status: BAS, ATG or no induction (NI). The occurrences of cytomegalovirus (CMV) infection, pneumonia, side effects, primary graft dysfunction (PGD), acute rejection, chronic allograft disfunction (CLAD) and death episodes were assessed during two years after LTx. A total of 124 patients were divided in 3 groups: 61 (49.2%) BAS; 43 (34.7%) ATG; 20 (16.1%) NI. The incidences of pneumonia and CMV were similar between induction groups. Additionally, there was no difference between the induction groups in PGD, acute rejection, CLAD, deaths and two-year survival. Side effects were reported only in ATG group (n = 20; 46.5%). In our study, BAS had a better safety profile than ATG in LTx with a similar efficacy.

Immunosuppression in Lung Transplantation

Immunosuppression in lung transplantation is an area devoid of robust clinical data. This chapter will review the history of immunosuppression in lung transplantation. Additionally, it will evaluate the three classes of induction, maintenance, and rescue immunosuppression in detail. Induction immunosuppression in lung transplantation aims to decrease incidence of lung allograft rejection, however infectious risk must be considered when determining if induction is appropriate and which agent is most favorable. Similar to other solid organ transplant patient populations, a multi-drug approach is commonly prescribed for maintenance immunosuppression to minimize single agent drug toxicities. Emphasis of this review is placed on key medication considerations including dosing, adverse effects, and drug interactions. Clinical considerations will be reviewed per drug class given available literature. Finally, acute cellular, antibody mediated, and chronic rejection are reviewed.

Antithymocyte globulin is associated with a lower incidence of de novo donor-specific antibody detection in lung transplant recipients: A single-center experience

Purpose

Induction immunosuppression has improved the long‐term outcomes after lung transplant. This is the first report exploring the association of induction immunosuppression with the development of de novo donor‐specific human leukocyte antigen (HLA) antibodies (DSA) in lung transplant recipients (LTR).

Methods

Sixty‐seven consecutive primary LTR were followed for 3 years posttransplant. A total of 41/67 (61%) LTR‐received induction immunosuppression using a single dose of rabbit Antithymocyte Globulin (rATG; 1.5 mg/kg) within 24 h of transplant. All recipients had a negative flow cytometry crossmatch on the day of transplant. Serum samples at 1, 3, 6, and 12 months posttransplant were assessed for the presence of de novo HLA DSA.

Results

De novo HLA DSA were detected in 22/67 (32.8%) LTR within 1‐year posttransplant. Of these, 9/41 (21.9%) occurred in the induction therapy group and 13/26 (50%) in the noninduction group. Class II DSA were detected in 3/41 (7.3%) LTR who received induction compared to 9/26 (34.6%) LTR without induction immunosuppression (p = .005). Differences in overall survival or freedom from chronic lung allograft dysfunction rates between the two groups were not statistically significant.

Conclusion

Induction immunosuppression utilizing a modified regimen of single‐dose rATG is associated with a significant reduction in de novo DSA production in LTR.

Tacrolimus monitoring parameters are not associated with acute cellular rejection following lung transplantation

PURPOSE

The purpose of this study was to evaluate the impact of tacrolimus drug monitoring parameters on the incidence of acute cellular rejection (ACR) in lung transplant recipients (LTRs).

METHODS

This was a retrospective study of patients who underwent lung transplantation at a single center. LTRs who were given tacrolimus during the first 6 months after transplantation and who underwent at least one bronchoscopy with biopsy were included. Tacrolimus time in therapeutic range (TTR) was calculated using Rosendaal's method. Time to therapeutic level, coefficient of variance (CoV), and median trough concentrations were also determined.

RESULTS

The study included 157 LTRs. ACR ≥ A1 grade was present in 46.5% of patients, and ACR ≥ A2 grade was present in 17.2%. There was no difference between tacrolimus TTR in patients with ACR ≥ A1 compared with those without ACR (47.4 ± 16.1 versus 46.2 ± 18.9%, p = 0.67) or in patients with ACR ≥ A2 grade compared with those with A0 or A1 ACR (46.0 ± 16.3 versus 47.0 ± 17.9%, p = 0.81). When comparing patients with any ACR grade A1 or higher with those without ACR, there was no difference in tacrolimus CoV (42.7 ± 11.0 versus 44.6 ± 12.4, p = 0.30), median tacrolimus trough concentration (9.9 ± 1.3 versus 9.8 ± 1.4 ng/mL, p = 0.66), or days to therapeutic level (9 versus 12 days, p = 0.057).

CONCLUSIONS

The results suggest that tacrolimus TTR, time in therapeutic range, and variability are not related to the presence of ACR in LTRs.

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.

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.

Lung transplantation for bronchiolitis obliterans syndrome after allogenic hematopoietic stem cell transplantation

Bronchiolitis obliterans syndrome (BOS) after hematopoietic stem cell transplantation (HSCT) is a major cause of morbidity and mortality with limited treatment options. Lung transplantation (LTX) has been rarely reported as a treatment option for selected HSCT recipients with this problem. In the present study, we reported six patients who underwent LTX due to BOS after HSCT (two females, four males) from January 2012 to December 2014 in our center. The median time from HSCT to diagnosis of BOS was 2.5 years (ranging from 1 to 5 years). At a median time of 4 years (ranging from 2 to 5 years) after diagnosis of BOS, four patients received bilateral sequential LTX, and two patients received single LTX. One of the recipients suffered from mild acute rejection after LTX, another suffered from primary lung graft dysfunction on post-operation day 2, and three experienced fungal infections. The median time for follow-up after LTX was 19.5 months (ranging from 12 to 39 months). At present, all patients are alive with good functional capacity and no relapse of BOS and hematologic malignancy conditions. Patients who received bilateral LTX have better pulmonary functions than patients who received single LTX.

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.

A randomized controlled trial of daclizumab versus anti-thymocyte globulin induction for heart transplantation

Background

The purpose of this study was to test the efficacy and safety of daclizumab (DZM) versus anti-thymocyte globulin (ATG) as a component of induction therapy in heart transplant recipients.

Methods

Thirty heart transplant patients were randomized to receive either ATG or DZM during induction therapy. Patients in the DZM group received an initial dose of 2 mg/kg intravenous (IV) at the time of transplant and 1 mg/kg IV on postoperative day 4.

Discussion

Recipient, donor, and intraoperative variables did not differ significantly between groups. The cost of induction therapy, total drug cost, and hospital ward costs were significantly less for the DZM group. Average absolute lymphocyte and platelet counts were significantly higher in the DZM group. There were no significant differences in the incidence of rejection, infection, malignancy, or steroid-induced diabetes. One year survival was excellent in both groups (87%, P = 0.1). Daclizumab is a safe component of induction therapy in heart transplantation.

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.

A randomized, double-blind, placebo-controlled, multicenter study of rabbit ATG in the prophylaxis of acute rejection in lung transplantation

ATG-Fresenius S (ATG-F) is a polyclonal anti-human-T-lymphocyte immunoglobulin preparation that has been clinically developed to prevent episodes of acute cellular rejection. This study evaluated the efficacy and safety of ATG-F at doses of 5 and 9 mg/kg versus placebo in adult recipients of a primary lung allograft. The primary efficacy composite end point was defined as death, graft loss, acute rejection and/or loss to follow-up within 12 months of transplantation. The interim analysis showed the ATG-F 5 mg/kg treatment to be inefficacious, and it would be impossible to enroll enough patients to power the study to show a difference between the 9 mg/kg arm and the placebo arm. Therefore, the main focus of the study shifted to the safety end points and a descriptive analysis of the primary end point. At 12 months posttransplant, the efficacy failure rate was not significantly different between the ATG-F 9 mg/kg group and the placebo group (40.2% vs. 36.7%, respectively). This large study did not demonstrate a significant reduction in acute cellular rejection, graft loss or death with single-dose induction therapy with ATG-F within the first year after lung transplantation.

Lung transplantation in patients with cystic fibrosis: special focus to infection and comorbidities

Despite advances in medical care, patients with cystic fibrosis still face limited life expectancy. The most common cause of death remains respiratory failure. End-stage cystic fibrosis can be treated with lung transplantation and is the third most common reason for which the procedure is performed. Outcomes for cystic fibrosis are better than most other lung diseases, but remain limited (5-year survival 60%). For patients with advanced disease lung transplantation appears to improve survival. Outcomes for patients with Burkholderia cepacia remain poor, although they are better for patients with certain genomovars. Controversy exists about Mycobacterium abscessus infection and appropriateness for transplant. More information is also becoming available for comorbidities, including diabetes and pulmonary hypertension among others. Extra-corporeal membrane oxygenation is used more frequently for end-stage disease as a bridge to lung transplantation and will likely be used more in the future.

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).

Bronchiolitis obliterans syndrome: the Achilles' heel of lung transplantation

Lung transplantation is a therapeutic option for patients with end-stage pulmonary disorders. Unfortunately, chronic lung allograft dysfunction (CLAD), most commonly manifest as bronchiolitis obliterans syndrome (BOS), continues to be highly prevalent and is the major limitation to long-term survival. The pathogenesis of BOS is complex and involves alloimmune and nonalloimmune pathways. Clinically, BOS manifests as airway obstruction and dyspnea that are classically progressive and ultimately fatal; however, the course is highly variable, and distinguishable phenotypes may exist. There are few controlled studies assessing treatment efficacy, but only a minority of patients respond to current treatment modalities. Ultimately, preventive strategies may prove more effective at prolonging survival after lung transplantation, but their remains considerable debate and little data regarding the best strategies to prevent BOS. A better understanding of the risk factors and their relationship to the pathological mechanisms of chronic lung allograft rejection should lead to better pharmacological targets to prevent or treat this syndrome.

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.

Post-transplant lymphoproliferative disorder after lung transplantation: a review of 35 cases

BACKGROUND

Post-transplant lymphoproliferative disorder (PTLD) is a complication of organ transplantation. The risk of developing PTLD varies depending on a number of factors, including the organ transplanted and the degree of immunosuppression used.

METHODS

We report a retrospective analysis of 35 patients with PTLD treated at our center after lung transplantation. Of 705 patients who received allografts, 34 (4.8%) developed PTLD. One patient underwent transplantation elsewhere and was treated at our center.

RESULTS

PTLD involved the allograft in 49% of our patients and the gastrointestinal (GI) tract lumen in 23%. Histologically, 39% of tumors were monomorphic and 48% polymorphic. The time to presentation defined the location and histology of disease. Of 17 patients diagnosed within 11 months of transplantation, PTLD involved the allograft in 12 (71%) and the GI tract in 1 (p = 0.01). This "early" PTLD was 85% polymorphic (p = 0.006). Conversely, of the 18 patients diagnosed more than 11 months after transplant, the lung was involved in 5 (28%) and the GI tract in 7 (39%; p = 0.01). "Late" PTLD was 71% monomorphic (p = 0.006). Median overall survival after diagnosis was 18.57 months. Overall survival did not differ between all lung transplant recipients and those who developed PTLD.

CONCLUSIONS

PTLD is an uncommon complication after lung transplantation, and its incidence declined remarkably in the era of modern immunosuppression. We report several factors that are important for predisposition toward, progression of, and treatment of PTLD after lung transplantation.

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.

Interleukin-2 receptor blockade with humanized monoclonal antibody for solid organ transplantation

IMPORTANCE OF THE FIELD

Induction therapy has reduced the incidence of acute rejection compared with historical standards. The potency of currently available induction immunosuppression is not without risk and should be carefully considered. Induction with daclizumab, an IL-2 receptor antagonist, has been used safely and effectively for over 10 years across different transplant types. As a result of daclizumab use, transplant centers are able to implement steroid-sparing or calcineurin minimization protocols. Unfortunately, the manufacturing costs have resulted in withdrawal of this agent from the market reducing the options for patients undergoing transplantation.

AREAS COVERED IN THIS REVIEW

This review will update the reader on recently published daclizumab studies in adult solid organ transplant recipients, focusing on comparative studies with other induction agents.

WHAT THE READER WILL GAIN

This paper will provide a summary of comparative studies between daclizumab and other induction therapies focusing on their efficacy and safety.

TAKE HOME MESSAGE

Novel applications, such as long-term use in combination with calcineurin-inhibitor dose reduction and its value in the treatment of acute or chronic rejection have yet to be explored. Since daclizumab has been withdrawn from the market, future IL-2 receptor blockade will have to be achieved with basiliximab, which is a chimeric, monoclonal antibody directed against the same epitope.

The impact of induction on survival after lung transplantation: an analysis of the International Society for Heart and Lung Transplantation Registry

BACKGROUND

The use of induction immunosuppression after lung transplantation remains controversial. In this study, we examined the impact of induction on survival after lung transplantation.

METHODS

We performed a retrospective cohort study of 3970 adult lung transplant recipients reported to the ISHLT Registry. We divided the cohort into three groups based on the use of induction: none, interleukin-2 receptor antagonists (IL-2 RA), and polyclonal antithymocyte globulins (ATG). We estimated graft survival using the Kaplan-Meier method and constructed a multivariable Cox proportional hazards model to examine the impact of induction on graft survival in the context of other variables.

RESULTS

During the study period, 2249 patients received no induction, 1124 received IL-2 RA, and 597 received ATG. Four years after transplantation, recipients treated with IL-2 RA had better graft survival (64%) than those treated with ATG (60%) and those who did not receive induction (57%; log rank p = 0.0067). This survival advantage persisted in the multivariable model for single and bilateral recipients treated with IL-2 RA compared to those who did not receive induction (RR = 0.82, p = 0.007). Similarly, bilateral recipients treated with ATG had a survival advantage over bilateral recipients who did not receive induction (RR = 0.78, p = 0.043), but single lung recipients treated with ATG did not have a survival advantage over single lung recipients who did not receive induction (RR = 1.06, p = 0.58).

CONCLUSIONS

Induction with lL-2 RA for single and bilateral lung recipients and induction with ATG for bilateral recipients are associated with a survival benefit, independent of other variables that might impact survival.

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.

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.

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.

Elevation of interleukin-15 protein expression in bronchoalveolar fluid in acute lung allograft rejection

BACKGROUND

Acute rejection remains a major source of morbidity in lung transplantation. Although interleukin (IL)-2 has been the principal T-cell growth factor implicated in acute rejection, IL-2 blockade does not prevent acute rejection completely. Recently, IL-15, a stromal cell-derived cytokine, has been found to share a similar biological function with IL-2. We hypothesized that IL-15 levels may be elevated in acute lung rejection in the presence of IL-2 blockade.

METHODS

Acute allograft rejection developed in 21 of 42 lung transplant recipients. BAL fluid (BALF) was analyzed for IL-2 and IL-15 protein expression by standard enzyme-linked immunosorbent assay.

RESULTS

The average (+/- SD) BALF IL-15 level was higher in lung transplant recipients with acute rejection compared to those without rejection (25 +/- 25 pg/mL vs 4.5 +/- 1.5 pg/mL, respectively; p < 0.0001). In addition, there appeared to be a bimodal distribution of BALF IL-15 levels in lung transplant recipients with acute rejection. BALF IL-2 levels were not associated with acute rejection. BALF IL-15 levels were not associated with bacterial, fungal, or cytomegalovirus infection.

CONCLUSION

These data show that BALF IL-15 levels are elevated in acute lung allograft rejection in the presence of IL-2 receptor blockade and may be an important mediator for acute rejection in lung transplantation.

Induction Therapy in Lung Transplantation: Initial Single-Center Experience Comparing Daclizumab and Antithymocyte Globulin

Acute and chronic rejection remain unresolved problems after lung transplantation, despite heavy multidrug immunosuppression. Because acute rejection is associated with inferior outcomes in lung transplantation, we have routinely employed antithymocyte globulin (ATG) or daclizumab as adjuncts to reduce the incidence of rejection episodes.

METHODS

We performed a controlled clinical trial of the two therapies to evaluate differences in postoperative rejection, infection, bronchiolitis obliterans syndrome (BOS) and host survival. Twenty-five consecutive lung transplant patients received ATG (n = 12; group 1) or daclizumab (n = 13; group 2) as an induction agent. The groups showed similar demographics and immunosuppression protocols, differ only in induction agent.

RESULTS

No differences were observed in the immediate postoperative outcomes, such as length of hospitalization, ICU stay, or time on ventilator. There were no significant differences in the number of episodes of acute rejection, freedom from BOS, or infections. Freedom from acute rejection was significantly greater with daclizumab than with ATG (P = .037). The 1-year survival for group 1 was 67% and for group 2, 77% (P = .584).

CONCLUSIONS

Daclizumab constitutes a safe and effective form of induction immunosuppressive therapy. Using a two-dose administration schedule, daclizumab prolonged the time without acute rejection compared to ATG. The differences in the incidence of infectious complications, acute rejection, or BOS as well as the short-term or long-term results were not significantly different. The results of the study justify the further use of daclizumab as an induction agent in patients following lung transplantation.

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.

Lung Transplantation: Current Status and Challenges

The lung is an anatomically complex vital organ whose normal physiology depends on actively regulated ventilation and perfusion, and maintenance of a delicate blood-air barrier over a huge surface area in direct contact with a potentially hostile environment. Despite significant progress over the past 25 years, both short- and long-term outcomes remain significantly inferior for lung recipients relative to other "solid" organs. This review summarizes the current status of lung transplantation so as to frame the principle challenges currently facing end-stage lung-failure patients and the practitioners who care for them.

A comparison of basiliximab and anti-thymocyte globulin as induction agents after lung transplantation

BACKGROUND

Interleukin-2 receptor antagonists have supplanted polyclonal antibody preparations as the most frequently used induction agents after lung transplantation, but the relative efficacy of these agents has not been firmly established.

METHODS

We retrospectively analyzed the efficacy of basiliximab compared with antithymocyte globulin among 157 adult lung transplant recipients at our center.

RESULTS

At 3, 6, and 12 months after transplantation, the median cumulative acute rejection A scores for the basiliximab group (2, 2, and 3, respectively) were significantly higher than those for the anti-thymocyte globulin group (1, 1, and 2, respectively; p = 0.003, 0.004, and 0.033, respectively). In addition, basiliximab recipients were more likely to develop acute rejection grade > or = A2 than anti-thymocyte globulin recipients; in fact, 60% of basiliximab recipients compared with 38% of anti-thymocyte globulin recipients developed their first episode of acute rejection grade > or = A2 in the first 100 days after transplantation (log-rank p = 0.04). Furthermore, basiliximab recipients were more likely to develop bronchiolitis obliterans syndrome than anti-thymocyte globulin recipients (log-rank p = 0.036). Two years after transplantation, 36% of basiliximab recipients and 26% of anti-thymocyte globulin recipients developed bronchiolitis obliterans syndrome. However, there were no significant differences in the incidences of cytomegalovirus viremia and pneumonitis between the 2 groups (p = 0.86 and 0.89, respectively).

CONCLUSIONS

Induction with anti-thymocyte globulin is associated with a lower burden of acute rejection and bronchiolitis obliterans syndrome compared with basiliximab, without a significant difference in the incidence of cytomegalovirus infections.

Airway cellular response to two different immunosuppressive regimens in lung transplant recipients

A number of new immunosuppressive drugs have become available in transplant medicine. We investigated the effects of two different immunosuppressive protocols on bronchoalveolar lavage fluid cellular characteristics in 34 lung transplant recipients who were treated with anti-thymocyte globulin induction therapy, cyclosporine, azathioprine (AZA), and prednisolone (regimen I), compared with 17 recipients receiving basiliximab induction, tacrolimus, AZA, and prednisolone (regimen II). We performed bronchoalveolar lavages between 15 and 40 d post-transplantation, in stable clinical condition and no acute rejection, cytomegalovirus, and/or respiratory tract infection. The regimen II treatment was associated with a significantly lower percentage lavage fluid lymphocytes than with regimen I. The CD4/CD8 ratio was significantly higher with regimen II than with regimen I: 1.56 (range 0.41-2.16) and 0.33 (0.04-0.95) respectively; p < 0.001, mainly because of a lower percentage CD8(+) cells with regimen II: 25% (12-51) vs. regimen I: 60% (34-77); p < 0.001. The percentage CD4(+) CD25(+) cells appeared lower with regimen II: 21% (10-88) vs. regimen I: 50% (0-87); p = 0.04. Overall survival was similar between the groups, whereas a beneficial trend in freedom of bronchiolitis obliterans syndrome was observed with regimen II. Airway lymphocyte subtypes are affected by the immunosuppressive protocol used. This observation should be taken into account when studying transplant recipients, and may contribute to our understanding of alloreactive airway disease.

Daclizumab induction in solid organ transplantation

Antibody induction therapy is used in solid organ transplantation to prevent rejection in the early postoperative period. It is especially useful in high-risk groups such as retransplants, patients with delayed graft function to delay the initiation of nephrotoxic calcineurin inhibitors (tacrolimus, cyclosporin), highly sensitised recipients and African-American recipients. Historically, antibody induction has been associated with a high incidence of adverse effects and a complicated administration regimen. Daclizumab is a monoclonal antibody that exerts its effect by binding to the alpha subunit (CD25) of the human interleukin (IL)-2 receptor on the surface of activated lymphocytes, thus preventing the binding of IL-2. It is used for induction therapy and is well-tolerated with easy administration. Although originally studied as a five-dose regimen, there is a growing accumulation of data that fewer doses (two or three) are efficacious and less costly for preventing rejection.

Bronchiolitis Obliterans Syndrome

Post-transplantation bronchiolitis obliterans syndrome (BOS) is a clinicopathological syndrome characterised histologically by obliterative bronchiolitis (OB) and physiologically by airflow limitation. It affects long-term survival with no consistently effective treatment strategy.An updated review of risk factors for OB/BOS, and approaches to prevention and treatment was performed through a systematic review of relevant studies between January 1990 and February 2005. The initial search identified 853 publications, with 56 articles reviewed after exclusions. Early acute rejection is the most significant risk factor, with late rejection (> or =3 months) also significant. Lymphocytic bronchitis/bronchiolitis is relevant, with later onset associated with greater risk. Viral infections are identified as significant risk factors. Human leukocyte antigen matching and OB/BOS development is a weaker association, but is stronger with acute rejection. Recipient and donor characteristics have a minor role. There is limited evidence that altering immunosuppression is effective in reducing the rate of decline in lung function. BOS reflects an allo-immunological injury, possibly triggered by cytomegalovirus and respiratory viral infections, or noninfectious injury. Immunological susceptibility may be reflected by more frequent acute rejection episodes. Preventative and therapeutic modifications in immunosuppression remain important. Identifying markers of immunological susceptibility and, hence, risk stratification requires further research.

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.

Bronchiolitis obliterans syndrome: Pathogenesis and management

Over the past 15 years, lung transplantation has become an established treatment for a variety of end-stage lung diseases, but medium- and long-term success has been limited by a high incidence of bronchiolitis obliterans syndrome (BOS). Immune mediated injury has been recognized as the leading cause of BOS, and the term is synonymous with chronic rejection. But recently, nonimmune mechanisms, such as gastroesophageal reflux, have been recognized as potential culprits. The results of various treatment options have generally been disappointing, and BOS has emerged as the leading cause of late morbidity and mortality after lung transplantation.

Yield of surveillance bronchoscopy for acute rejection and lymphocytic bronchitis/bronchiolitis after lung transplantation

BACKGROUND

Better understanding of the timing and pattern of surveillance bronchoscopy findings after lung transplantation could influence the timing and frequency of surveillance bronchoscopy. We present our surveillance bronchoscopy experience and test the hypothesis that patients not encountering early acute rejection or lymphocytic bronchitis/bronchiolitis are less likely to have subsequent occult occurrences in the 1st year after lung transplantation.

METHODS

We conducted a retrospective study of 204 patients who underword transplantation between 1996 and 2000. Based on contemporary biopsy-specimen grading in the first 100 days, we formed 2 groups: No Early Rejection and Early Rejection. We compared subsequent yields of surveillance bronchoscopy and the incidence of acute rejection or of lymphocytic bronchitis/bronchiolitis.

RESULTS

We reviewed 645 biopsies taken from 204 recipients during the first 100 days to classify patients into a No Early Rejection Group (n=67) or an Early Rejection Group (n=137). Yield of surveillance bronchoscopy for acute rejection or lymphocytic bronchitis/bronchiolitis was 31% with the greatest yield during the first 30 days (45%), and then decreasing to 26% (p <0.001). After Day 100, 71% of occult acute rejection episodes involved minimal (A1) lesions. Yield of surveillance bronchoscopy after Day 100 was 20% in the No Early Rejection Group and was 27% in the Early Rejection Group (p=0.22). Incidence of acute rejection or lymphocytic bronchitis/bronchiolitis after Day 100 was 41% in the No Early Rejection Group and was 50% in the Early Rejection Group (p=0.17).

CONCLUSION

Surveillance bronchoscopy detects occult acute rejection or lymphocytic bronchitis/bronchiolitis in approximately one-third of biopsy specimens during the 1st year, with the majority of late abnormalities being minimal (A1) rejection. The absence of acute rejection or lymphocytic bronchitis/bronchiolitis during the first 100 days does not predict freedom from such events in the remainder of the 1st year.

Comparison of three tacrolimus-based immunosuppressive regimens in lung transplantation

Immunosuppressive therapy for solid organ transplantation has significantly evolved over the past decade. While these therapies have been found to be beneficial in abdominal organ transplantation, the efficacy of these therapies remains unclear in lung transplantation. We retrospectively compared three potent immunosuppressive regimens in our lung transplant population: Group 1 (tacrolimus/azathioprine/prednisone), Group 2 (tacrolimus/azathioprine/prednisone/daclizumab) and Group 3 (tacrolimus/mycophenolate mofetil/prednisone/daclizumab). We compared these three groups with respect to 3-year rates of acute rejection, chronic rejection, infection and survival. A total of 109 patients was followed during the course of this study. There were 32 patients in Group 1, 49 patients in Group 2 and 28 patients in Group 3. Freedom from acute rejection at 1 and 3 years were higher in Group 3 compared with Group 1 (p < 0.05). The overall incidence of infection up to 3 years after transplantation was comparable among all three groups. Freedom from chronic rejection and survival at 1 and 3 years did not differ among the three groups. In conclusion, we determined the safety and efficacy of three potent immunosuppressive regimens in lung transplantation. Addition of daclizumab and MMF to a tacrolimus-based immunosuppressive regimen decreased the incidence of acute rejection episodes without increasing any adverse events in our lung transplantation population.