Cyclosporine C2 Target Levels and Acute Cellular Rejection After Lung Transplantation

Lung Allograft Rejection

Rejection is a major complication following lung transplantation. Acute cellular rejection (ACR), and antibody-mediated rejection (AMR) are risk factors for the subsequent development of chronic lung allograft dysfunction and worse outcomes after transplantation. Although ACR has well-defined histopathologic diagnostic criteria and grading, the diagnosis of AMR requires a multidisciplinary diagnostic approach. This article reviews the identification, clinical and pathologic features of, and therapeutic options for ACR and AMR.

Acute Rejection in the Modern Lung Transplant Era

Acute cellular rejection (ACR) remains a common complication after lung transplantation. Mortality directly related to ACR is low and most patients respond to first-line immunosuppressive treatment. However, a subset of patients may develop refractory or recurrent ACR leading to an accelerated lung function decline and ultimately chronic lung allograft dysfunction. Infectious complications associated with the intensification of immunosuppression can also negatively impact long-term survival. In this review, we summarize the most recent evidence on the mechanisms, risk factors, diagnosis, treatment, and prognosis of ACR. We specifically focus on novel, promising biomarkers which are under investigation for their potential to improve the diagnostic performance of transbronchial biopsies. Finally, for each topic, we highlight current gaps in knowledge and areas for future research.

Lung Transplantation and Precision Medicine

Lung transplantation is an accepted therapeutic option for end-stage lung diseases. Its history starts in the 1940s, initially hampered by early deaths due to perioperative problems and acute rejection. Improvement of surgical techniques and the introduction of immunosuppressive drugs resulted in longer survival. Chronic lung allograft dysfunction (CLAD), a new complication appeared and remains the most serious complication today. CLAD, the main reason why survival after lung transplantation is impaired compared to other solid-organ transplantations is characterized by a gradually increasing shortness of breath, reflected in a deterioration of pulmonary function status, respiratory insufficiency and possibly death.

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.

Three-year results of an investigator-driven multicenter, international, randomized open-label de novo trial to prevent BOS after lung transplantation

BACKGROUND

Chronic lung allograft dysfunction (CLAD), predominantly manifest as bronchiolitis obliterans syndrome (BOS), is the primary cause of morbidity and death after lung transplantation. We assessed the efficacy and safety of 2 de novo immunosuppression protocols to prevent BOS.

METHODS

This was a multicenter, prospective, international, randomized (1:1) open-label superiority study of de novo enteric-coated mycophenolate sodium (MPS) vs delayed-onset everolimus (RAD), both arms in combination with cyclosporine (CsA) monitored by 2-hour post-dose (C2) levels, and corticosteroids. Target C2 levels were lower in the RAD group because RAD is known to potentiate CsA nephrotoxicity. Cytolytic induction therapy was not used. Patients were stratified at entry for cystic fibrosis. Confirmation of anastomotic healing was required for randomization. Primary efficacy was freedom from BOS Grade 1 on intention-to-treat (ITT) analysis. Secondary efficacy parameters were patient and graft survival and severity of rejection. Treatment failure was defined by graft loss, patient death, drug cessation, or need for other therapy.

RESULTS

The 3-year freedom from BOS Grade 1 was 70% for MPS (n = 80) vs 71% for RAD (n = 84; p = 0.95 by log-rank) in ITT but was lower in the RAD arm of the per-protocol population (p = 0.03). The 3-year survival was 84% (MPS) vs 76% (RAD; p = 0.19 by log-rank). Thirteen patients switched from MPS vs 31 from RAD (p < 0.01). Days on MPS were greater than days on RAD (p < 0.01). Rejection events proven by biopsy specimen were more common on MPS (p = 0.02), as were leucopenia (p < 0.01), diarrhea (p < 0.01), and cytomegalovirus infection (p = 0.04). Venous thromboembolism was more frequent on RAD (p = 0.02). Creatinine at 3 years was 160 ± 112 μmol/1iter in MPS patients vs 152 ± 98 μmol/1iter in RAD patients (p = 0.67).

CONCLUSIONS

This 3-year ITT analysis found no significant difference between arms but was underpowered to accept the null hypothesis that RAD and MPS have equivalent efficacy in preventing BOS or death after lung transplantation.

Correlations between cyclosporine concentrations at 2 hours post-dose and trough levels with functional outcomes in de novo lung transplant recipients

BACKGROUND

Although the reliability of cyclosporine (CyA) concentration at 2 (C2) hours postdosing has been established for kidney, liver, and heart transplant recipients, its use in lung cases remains to be validated. We investigated the relationship between CyA dual time point monitoring and long-term functional outcomes after lung transplantation.

METHODS

We included data from 38 lung transplant recipients receiving CyA, azathioprins, and steroids in the study. CyA dosages were based on the trough concentrations. CyA concentrations at 0 (C0) and 2 (C2) hours postdosing were obtained at 1, 2, 3, 6, 9, 12, 15, 18, and 24 months postoperative. We retrospectively compared average CyA level (C0 and C2) during the first 3 posttransplantation months with forced expiratory volume in 1 second (FEV1), forced vital capacity (FVC), forced expiratory flow 25%-75 % (FEF 25-75), creatinine, systolic blood pressure (SBP), and diastolic blood pressure (DBP) using regression analysis via generalized estimating equations (GEE).

RESULTS

Only improvement in FVC (P = .033) and deterioration of SBP (P < .001) were related to C0 monitoring. No correlation was observed between C0 and FEV1 (P = .13), FEF 25-75 (P = .48), creatinine (P = .07), and DBP (P = .97). Nor was any relationship observed between C2 concentrations and FEV1 (P = .64), FVC (P = .38), FEF 25-75 (P = .09), creatinine (P = .95), SBP (P = .73), or DBP (P = .51).

CONCLUSION

There was a lack of a relationship between CyA concentrations (C0 and C2) and functional outcomes among de novo lung transplantations except for a positive correlation of 0 value with long-term improved FVC and increased SBP. This study suggested that C2 determinations may not improving lung recipient management.

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.

Optimizing post-transplant outcomes in lung transplantation

Lung transplant recipients are at risk of numerous complications, which range from early events, such as primary graft dysfunction, to late events, including opportunistic infection or graft loss caused by chronic rejection. Although lung transplantation is often the only therapeutic option that can improve quality of life and prolong survival for many forms of end-stage lung disease, survival following lung transplantation is significantly worse than survival following transplantation of other solid organs. Carefully choosing potential recipients for listing, maximizing the likelihood that donor organs will function well following implantation, appropriate use of immunosuppressive agents to prevent allograft rejection, prophylactic or pre-emptive strategies to prevent allograft infection and appropriate surveillance to detect significant complications are key to maximizing the likelihood of prolonged graft and patient survival while avoiding significant complications following lung transplantation. Post-transplant outcomes will be optimized by a team approach to comprehensive management of the lung transplantation recipient combined with vigilant surveillance to detect complications in a timely fashion.

Pharmacokinetic optimization of immunosuppressive therapy in thoracic transplantation: part II

Part I of this article, which appeared in the previous issue of the Journal, reviewed calcineurin inhibitors--ciclosporin and tacrolimus. In part II, we review the pharmacokinetics and therapeutic drug monitoring of mycophenolate and mammalian target of rapamycin inhibitors--sirolimus and everolimus--in thoracic transplantation, and we provide an overall discussion and suggest various areas for future study.

Cyclosporine C2 levels have impact on incidence of rejection in de novo lung but not heart transplant recipients: the NOCTURNE study

BACKGROUND

Cyclosporine (CsA) absorption varies early after transplantation and can be accurately assessed by the area under the absorption curve (AUC). The 2-hour post-dose (C2) level of CsA in whole blood is reported to be a useful surrogate marker of CsA AUC in kidney and liver transplant monitoring, but should be further explored in thoracic organ recipients.

METHODS

In a 12-month study we included de novo lung (n = 95) and heart (n = 96) recipients. All participants received cyclosporine (Sandimmun Neoral) monitored by C0 and blood was collected for analysis of C2 retrospectively. Abbreviated AUC (AUC(0-4)) was measured at 7 days and 3 months. Primary outcome was C2 relation to the frequency of acute cellular rejection (ACR) needing treatment and possible decline in measured glomerular filtration rate (mGFR). Recipients were divided into lower, middle and upper third C2 groups based on 2-week post-operative values (tertiles T1 to T3).

RESULTS

C2 was the most robust substitute for AUC(0-4) in the group of patients studied. For lung, but not heart, recipients there were differences in mean number of ACRs (p = 0.05), incidence of any rejections (p = 0.04), mean number of any rejections (p = 0.001) and time to first rejection (p = 0.03) between T1 and T3. C2 did not predict reduction in mGFR.

CONCLUSIONS

C2 is a sensitive predictor for ACR in lung, but not heart, recipients, C2 was not predictive of a decline in mGFR. This study suggests that management of lung recipients by C2 may diminish the number of ACRs.

Pharmacokinetic optimization of immunosuppressive therapy in thoracic transplantation: part I

Although immunosuppressive treatments and therapeutic drug monitoring (TDM) have significantly contributed to the increased success of thoracic transplantation, there is currently no consensus on the best immunosuppressive strategies. Maintenance therapy typically consists of a triple-drug regimen including corticosteroids, a calcineurin inhibitor (ciclosporin or tacrolimus) and either a purine synthesis antagonist (mycophenolate mofetil or azathioprine) or a mammalian target of rapamycin inhibitor (sirolimus or everolimus). The incidence of acute and chronic rejection and of mortality after thoracic transplantation is still high compared with other types of solid organ transplantation. The high allogenicity and immunogenicity of the lungs justify the use of higher doses of immunosuppressants, putting lung transplant recipients at a higher risk of drug-induced toxicities. All immunosuppressants are characterized by large intra- and interindividual variability of their pharmacokinetics and by a narrow therapeutic index. It is essential to know their pharmacokinetic properties and to use them for treatment individualization through TDM in order to improve the treatment outcome. Unlike the kidneys and the liver, the heart and the lungs are not directly involved in drug metabolism and elimination, which may be the cause of pharmacokinetic differences between patients from all of these transplant groups. TDM is mandatory for most immunosuppressants and has become an integral part of immunosuppressive drug therapy. It is usually based on trough concentration (C(0)) monitoring, but other TDM tools include the area under the concentration-time curve (AUC) over the (12-hour) dosage interval or the AUC over the first 4 hours post-dose, as well as other single concentration-time points such as the concentration at 2 hours. Given the peculiarities of thoracic transplantation, a review of the pharmacokinetics and TDM of the main immunosuppressants used in thoracic transplantation is presented in this article. Even more so than in other solid organ transplant populations, their pharmacokinetics are characterized by wide intra- and interindividual variability in thoracic transplant recipients. The pharmacokinetics of ciclosporin in heart and lung transplant recipients have been explored in a number of studies, but less is known about the pharmacokinetics of mycophenolate mofetil and tacrolimus in these populations, and there are hardly any studies on the pharmacokinetics of sirolimus and everolimus. Given the increased use of these molecules in thoracic transplant recipients, their pharmacokinetics deserve to be explored in depth. There are very few data, some of which are conflicting, on the practices and outcomes of TDM of immunosuppressants after thoracic transplantation. The development of sophisticated TDM tools dedicated to thoracic transplantation are awaited in order to accurately evaluate the patients' exposure to drugs in general and, in particular, to immunosuppressants. Finally, large cohort TDM studies need to be conducted in thoracic transplant patients in order to identify the most predictive exposure indices and their target values, and to validate the clinical usefulness of improved TDM in these conditions. In part I of the article, we review the pharmacokinetics and TDM of calcineurin inhibitors. In part II, we will review the pharmacokinetics and TDM of mycophenolate and mammalian target of rapamycin inhibitors, and provide an overall discussion along with perspectives.

Successful lung transplantation for adolescents at a hospital for adults

OBJECTIVE

To describe the results of lung transplantation (LTx) in adolescents at a hospital for adults.

DESIGN AND SETTING

Prospective cohort study set in an LTx unit at an adult tertiary referral hospital from 1991 to 2006.

PATIENTS

37 consecutive adolescent lung transplant recipients including 13 males and 24 females (mean age, 16.7+/-2.0 [SD] years; range 12-19 years) who received heart-lung (six patients) or bilateral LTx (31 patients) for cystic fibrosis (29), congenital heart disease (four), acute respiratory failure (two), or another disorder (two). Two patients were transplanted after invasive ventilation, five after non-invasive ventilation and two after extracorporeal membrane oxygenation.

MAIN OUTCOME MEASURES

Overall survival compared with an adult cohort; survival free of bronchiolitis obliterans syndrome (BOS); overall and BOS-free survival in those transplanted before and after January 2000.

RESULTS

Mean waiting time was 273 days (range, 5-964 days; median, 163 days), mean donor age was 28 years (range, 9-53 years). Median inpatient stay was 11 days (range, 7-94 days). Mean follow-up was 1540+/-1357 days (range, 35-5163 days). The 5-year survival rate for the 16 patients transplanted before January 2000 was 38%, versus 74% for the 21 transplanted since January 2000 (P=0.05; Mantel-Cox). Overall, 18 of 35 evaluable patients developed BOS. Only BOS was associated with an increased mortality risk (P<0.01).

CONCLUSION

LTx may be performed successfully in adolescents at a hospital for adults.

The Clinical Benefits of Cyclosporine C2-Level Monitoring: A Systematic Review

BACKGROUND

Monitoring of cyclosporine microemulsion (Neoral) using 2-hour postdose (C2) levels is alleged to improve clinical outcomes, but the efficacy of this strategy is uncertain.

METHODS

A systematic literature search was performed for trials directly comparing patients monitored with C2 levels with those monitored by trough (C0) levels. Primary outcomes assessed were renal function and acute rejection.

RESULTS

A total of 29 studies met the inclusion criteria. Only 10 of these were randomized controlled trials. Overall quality was poor and this precluded meta-analysis. The most consistent finding in de novo renal, hepatic, and cardiac transplant recipients is a higher mean cyclosporine dose in the early postoperative period in C2 monitored patients. There is no clear evidence that this leads to impaired renal function. In the majority of studies, the monitoring strategy had no significant effect on the rate of acute rejection. In stable transplant recipients, the majority of studies show a reduction in mean cyclosporine dose with adoption of C2 monitoring. No obvious clinical benefit was derived from this reduction in dose.

CONCLUSION

In de novo transplant patients, there is little evidence from prospective studies to support the theoretical benefits of C2 monitoring. Potential dose reductions in stable patients may reduce costs, but no short-term clinical benefit is seen. Quality of studies in this area is poor, and the practical limitations of C2 monitoring mean that further evidence is required before a strategy for the administration of cyclosporine based on C2 levels can be recommended.