Induction therapy in lung transplantation

Prevalence and clinical significance of potential drug-drug interactions among lung transplant patients

Background: Drug-drug interactions (DDIs) are a major but preventable cause of adverse drug reactions. There is insufficient information regarding DDIs in lung transplant recipients. Objective: This study aimed to determine the prevalence of potential DDIs (pDDIs) in intensive care unit (ICU) lung transplant recipients, identify the real DDIs and the most frequently implicated medications in this vulnerable population, and determine the risk factors associated with pDDIs. Methods: This retrospective cross-sectional study included lung transplant recipients from January 2018 to December 2021. Pertinent information was retrieved from medical records. All prescribed medications were screened for pDDIs using the Lexicomp® drug interaction software. According to this interaction software, pDDIs were classified as C, D, or X (C = monitor therapy, D = consider therapy modification, X = avoid combination). The Drug Interaction Probability Scale was used to determine the causation of DDIs. All statistical analysis was performed in SPSS version 26.0. Results: 114 patients were qualified for pDDI analysis, and total pDDIs were 4051. The most common type of pDDIs was category C (3323; 82.0%), followed by D (653; 16.1%) and X (75; 1.9%). Voriconazole and posaconazole were the antifungal medicine with the most genuine DDIs. Mean tacrolimus concentration/dose (Tac C/D) before or after co-therapy was considerably lower than the Tac C/D during voriconazole or posaconazole co-therapy (p < 0.001, p = 0.027). Real DDIs caused adverse drug events (ADEs) in 20 patients. Multivariable logistic regression analyses found the number of drugs per patient (OR, 1.095; 95% CI, 1.048-1.145; p < 0.001) and the Acute Physiology and Chronic Health Evaluation II (APACHE Ⅱ) score (OR, 1.097; 95% CI, 1.021-1.179; p = 0.012) as independent risk factors predicting category X pDDIs. Conclusion: This study revealed a high incidence of both potential and real DDIs in ICU lung transplant recipients. Immunosuppressive drugs administered with azole had a high risk of causing clinically significant interactions. The number of co-administered drugs and APACHE Ⅱ score were associated with an increased risk of category × drug interactions. Close monitoring of clinical and laboratory parameters is essential for ensuring successful lung transplantation and preventing adverse drug events associated with DDIs.

Current perspective of immunomodulators for lung transplant

Lung transplantation is an effective treatment option for selected patients suffering from end-stage lung disease. More intensive immunosuppression is enforced after lung transplants owing to a greater risk of rejection than after any other solid organ transplants. The commencing of lung transplantation in the modern era was in 1983 when the Toronto Lung Transplant Group executed the first successful lung transplant. A total of 43,785 lung transplants and 1365 heart-lung transplants have been performed from 1 Jan 1988 until 31 Jan 2021. The aim of this review article is to discuss the existing immunosuppressive strategies and emerging agents to prevent acute and chronic rejection in lung transplantation.

Risk factors of bronchial dehiscence after primary lung transplantation

BACKGROUND

Although the incidence of bronchial dehiscence following lung transplantation has decreased significantly due to improvements in perioperative managements and surgical techniques, it remains a devastating postoperative complication associated with high morbidity and mortality.

METHODS

We retrospectively reviewed 811 lung transplantation performed at our institution between January 2011 and December 2020. Bronchial dehiscence was confirmed with flexible bronchoscopy, computed tomography (CT) scan, or clinical findings grade using International Society for Heart and Lung Transplantation recommendations.

RESULTS

Bronchial dehiscence was diagnosed in 38 patients (4.7%). The overall survival rates of the patients with bronchial dehiscence were significantly worse than those of the patients without bronchial dehiscence (p = .003). Multivariate analysis identified use of our basiliximab induction protocol (odds ratio = 3.03, p = .008) as an independent predictive factor of postoperative airway dehiscence in our multivariable model, along with total ventilator duration (odds ratio = 1.02, p = .002).

CONCLUSIONS

Based on our analysis, patients that underwent our basiliximab induction protocol for lung transplantation experienced a higher rate of postoperative bronchial dehiscence when compared with patients who receive alemtuzumab induction. We believe this may be associated with a higher steroid exposure in this population. Additional studies are necessary to further characterize the relationship between different induction protocols and bronchial dehiscence following transplantation.

Donor selection for multiorgan transplantation

PURPOSE OF REVIEW

There is limited data and guidance on donor selection for multiorgan transplantation. In this article, we review the current Organ Procurement and Transplantation Network policy on multiorgan allocation and the ideal donor criteria for each specific organ, in order to provide a framework to guide donor selection for various scenarios of multiorgan transplantation, including heart-kidney, heart-lung, heart-liver and heart-kidney-liver transplant procedures.

RECENT FINDINGS

Combined heart-kidney transplantation is the most common multiorgan transplant procedure and requires the most stringent HLA matching to ensure optimal graft survival. Using the virtual crossmatch and desensitization therapies can shorten waitlist times without increasing posttransplant rejection or mortality rates. The ideal heart-lung donor tends to be younger than other multiorgan transplants, and more tolerant to HLA mismatch, but ideally requires donors with no prior history of smoking, a short period of time on mechanical ventilation, adequate oxygenation and absence of pulmonary infection. The ideal heart-liver donor is often driven by criteria specific to the donor heart. Finally, several observational studies suggest that livers are more tolerant to HLA mismatch than other organs, and offer some degree of immune protection in combined organ transplants.

SUMMARY

Multiorgan transplantation is a steadily growing field. The required short ischemic time for the donor heart is often the limiting factor, as well as the scarcity of appropriate donors available within geographical confines. In general, as with single organ transplantation, younger age, size matching, few medical comorbidities and HLA compatibility confer the best posttransplant outcomes.

Rare indications for a lung transplant. A European Society of Thoracic Surgeons survey

OBJECTIVES

The European Society of Thoracic Surgeons Lung Transplantation Working Group promoted a survey to evaluate overall survival in a large cohort of patients receiving lung transplants for rare pulmonary diseases.

METHODS

We conducted a retrospective multicentre study. The primary end point was overall survival; secondary end points were survival of patients with the most common diagnoses in the context of rare pulmonary diseases and chronic lung allograft dysfunction (CLAD)-free survival. Finally, we analysed risk factors for overall survival and CLAD-free survival.

RESULTS

Clinical records of 674 patients were extracted and collected from 13 lung transplant centres; diagnoses included 46 rare pulmonary diseases. Patients were followed for a median of 3.1 years. The median survival after a lung transplant was 8.5 years. The median CLAD-free survival was 8 years. The multivariable analysis for mortality identified CLAD as a strong negative predictor [hazard ratio (HR) 6.73)], whereas induction therapy was a protective factor (HR 0.68). The multivariable analysis for CLAD occurrence identified induction therapy as a protective factor (HR 0.51). When we stratified patients by CLAD occurrence in a Kaplan-Meier plot, the survival curves diverged significantly (log-rank test: P < 0.001). Patients with rare diseases who received transplants had chronic rejection rates similar to those of the general population who received transplants.

CONCLUSIONS

We observed that overall survival and CLAD-free survival were excellent. We support the practice of allocating lungs to patients with rare pulmonary diseases because a lung transplant is both effective and ethically acceptable.

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.

Mycobacterial Infections in Solid Organ and Hematopoietic Stem Cell Transplantation

Mycobacterial infections are uncommon in solid organ and hematopoietic stem cell transplant recipients but carry significant morbidity and mortality. Donor screening strategies for tuberculosis should be emphasized in high-risk populations. Both tuberculosis and nontuberculous mycobacterial infections can have pulmonary and extrapulmonary manifestations of infections. Recommended treatment regimens typically involve multiple drugs with significant adverse effects and drug interactions.

Basiliximab application on liver recipients: a meta-analysis of randomized controlled trials

BACKGROUND

The benefits of the application of basiliximab induction therapy in liver transplantation are not clear. The present meta-analysis was to evaluate the pros and cons of basiliximab use in liver transplantation.

DATA SOURCES

We searched the associated publications in English from July 1998 to December 2015 in the following databases: MEDLINE, PubMed, Ovid, EMBASE, Web of Science and Cochrane Library.

RESULTS

Basiliximab significantly decreased the incidence of de novo diabetes mellitus after liver transplantation (RR=0.56; 95% CI: 0.34-0.91; P=0.02). Subgroup analysis showed that basiliximab in combination with steroids-free immunosuppressant significantly decreased the incidence of biopsy-proven acute rejection (RR=0.62; 95% CI: 0.39-0.97; P=0.04) and new-onset hypertension (RR=0.62; 95% CI: 0.42-0.93; P=0.02).

CONCLUSIONS

Basiliximab may be effective in reducing de novo diabetes mellitus. What is more, basiliximab in combination with steroids-free immunosuppressant shows statistical benefit to reduce biopsy-proven acute rejection and de novo hypertension.

Efficacy and safety of basiliximab in liver transplantation for patients with hepatitis B virus-related diseases: a single centre study

AIMS

We aim to evaluate the efficacy and safety of basiliximab in liver transplantation (LT) for patients with hepatitis B virus-related diseases.

METHODS

A total of 268 patients with hepatitis B virus-related diseases undergoing LT were enrolled and divided into two groups according to the usage of basiliximab. Total survival, the survival of high-risk patients defined by the posttransplant model for predicting mortality, acute rejection rate, biochemical parameters and other follow-up data were compared between the two groups.

RESULTS

Group Bas was composed of 131 patients who received basiliximab, and Group Triple enrolled the other 137 patients who did not. Between the two groups, there was no significant difference in the cumulative survival of patients without hepatocellular carcinoma (HCC) or in the cumulative survival of patients with HCC. For patients with benign end-stage liver diseases, Group Bas had more patients with a high risk of short- and medium-term mortality than Group Triple (22.81% vs. 8.85%, p = 0.017), but the survival curves of the two groups were not significantly different. The 1-year incidence of acute rejection was lower in Group Bas, although the difference was not significant (8.75% vs. 15.33%, p > 0.05). In both Group Bas and Group Triple, the level of serum creatinine (Scr) at 1 week posttransplantation was significantly lower than pretransplantation (61.00 vs. 88.50 μmol/l, p < 0.001; 61.50 vs. 74.00 μmol/l, p < 0.001; respectively). There was a significant difference in the pretransplantation Scr between the two groups (88.50 vs. 74.00 μmol/l, p = 0.005), but the values of Scr decreased to the same level 1 week (61.00 vs. 61.50 μmol/l, p > 0.05) and 4 weeks (61.00 vs. 59.00 μmol/l, p > 0.05) after transplantation. Significantly fewer recipients in Group Bas experienced hepatitis B relapse than in Group Triple (2/131 vs. 13/137, p = 0.006).

CONCLUSIONS

A basiliximab-induced immunosuppressive protocol is a safe regimen that achieves similar survival without increasing the acute rejection rate for LT recipients with hepatitis B virus-related diseases. For patients with benign end-stage liver diseases, this regimen reduces medium-term mortality in high-risk patients. This regimen remarkably improves renal function in the first month after LT and is correlated with a decreased hepatitis B recurrence rate in adult patients after LT.

Challenging immunosuppression treatment in lung transplant recipients with kidney failure

Kidney failure after lung transplantation is a risk factor for chronic kidney disease. Calcineurin inhibitors are immunosuppressants which play a major role in terms of postoperative kidney failure after lung transplantation. We report our preliminary experience with the anti-interleukin-2 monoclonal antibody Basiliximab utilized as a "calcineurin inhibitor-free window" in the setting of early postoperative kidney failure after lung transplantation. Between 2012 and 2015 nine lung transplant patients who developed kidney failure for more than 14 days were included. Basiliximab was administrated in three doses (Day 0, 4, and 20) whilst Tacrolimus was discontinued or reduced to maintain a serum level between 2 and 4 ng/mL. Baseline glomerular filtration rate pre transplant was normal for all patients. Seven patients completely recovered from kidney failure (67%, mean eGFR pre and post Basiliximab: 42.3 mL/min/1.73 m(2) and 69 mL/min/1.73 m(2)) and were switched back on Tacrolimus. Only one of these patients still needs ongoing renal replacement therapy. Two patients showed no recovery from kidney failure and did not survive. Basiliximab might be a safe and feasible therapeutical option in patients which are affected by calcineurin inhibitor-related kidney failure in the early post lung transplant period. Further studies are necessary to confirm our preliminary results.

Organ-specific differences in achieving tolerance

PURPOSE OF REVIEW

When it comes to tolerance induction, kidney allografts behave differently from heart allografts that behave differently from lung allografts. Here, we examine how and why different organ allografts respond differently to the same tolerance induction protocol.

RECENT FINDINGS

Allograft tolerance has been achieved in experimental and clinical kidney transplantation. Inducing tolerance in experimental recipients of heart and lung allografts has, however, proven to be more challenging. New protocols being developed in nonhuman primates based on mixed chimerism and cotransplantation of tolerogenic organs may provide mechanistic insights to help overcome these challenges.

SUMMARY

Tolerance induction protocols that are successful in patients transplanted with 'tolerance-prone' organs such as kidneys and livers will most likely not succeed in recipients of 'tolerance-resistant' organs such as hearts and lungs. Separate clinical trials using more robust tolerance protocols will be required to achieve tolerance in heart and lung recipients.

New directions for rabbit antithymocyte globulin (Thymoglobulin(®)) in solid organ transplants, stem cell transplants and autoimmunity

In the 30 years since the rabbit antithymocyte globulin (rATG) Thymoglobulin^® was first licensed, its use in solid organ transplantation and hematology has expanded progressively. Although the evidence base is incomplete, specific roles for rATG in organ transplant recipients using contemporary dosing strategies are now relatively well-identified. The addition of rATG induction to a standard triple or dual regimen reduces acute cellular rejection, and possibly humoral rejection. It is an appropriate first choice in patients with moderate or high immunological risk, and may be used in low-risk patients receiving a calcineurin inhibitor (CNI)-sparing regimen from time of transplant, or if early steroid withdrawal is planned. Kidney transplant patients at risk of delayed graft function may also benefit from the use of rATG to facilitate delayed CNI introduction. In hematopoietic stem cell transplantation, rATG has become an important component of conventional myeloablative conditioning regimens, following demonstration of reduced acute and chronic graft-versus-host disease. More recently, a role for rATG has also been established in reduced-intensity conditioning regimens. In autoimmunity, rATG contributes to the treatment of severe aplastic anemia, and has been incorporated in autograft projects for the management of conditions such as multiple sclerosis, Crohn’s disease, and systemic sclerosis. Finally, research is underway for the induction of tolerance exploiting the ability of rATG to induce immunosuppresive cells such as regulatory T-cells. Despite its long history, rATG remains a key component of the immunosuppressive armamentarium, and its complex immunological properties indicate that its use will expand to a wider range of disease conditions in the future.

Lung transplantation: a treatment option in end-stage lung disease

BACKGROUND

Lung transplantation is the final treatment option in the end stage of certain lung diseases, once all possible conservative treatments have been exhausted. Depending on the indication for which lung transplantation is performed, it can improve the patient's quality of life (e.g., in emphysema) and/ or prolong life expectancy (e.g., in cystic fibrosis, pulmonary fibrosis, and pulmonary arterial hypertension). The main selection criteria for transplant candidates, aside from the underlying pulmonary or cardiopulmonary disease, are age, degree of mobility, nutritional and muscular condition, and concurrent extrapulmonary disease. The pool of willing organ donors is shrinking, and every sixth candidate for lung transplantation now dies while on the waiting list.

METHOD

We reviewed pertinent articles (up to October 2013) retrieved by a selective search in Medline and other German and international databases, including those of the International Society for Heart and Lung Transplantation (ISHLT), Eurotransplant, the German Institute for Applied Quality Promotion and Research in Health-Care (Institut für angewandte Qualitätsförderung und Forschung im Gesundheitswesen, AQUA-Institut), and the German Foundation for Organ Transplantation (Deutsche Stiftung Organtransplantation, DSO).

RESULTS

The short- and long-term results have markedly improved in recent years: the 1-year survival rate has risen from 70.9% to 82.9%, and the 5-year survival rate from 46.9% to 59.6%. The 90-day mortality is 10.0%. The postoperative complications include acute (3.4%) and chronic (29.0%) transplant rejection, infections (38.0%), transplant failure (24.7%), airway complications (15.0%), malignant tumors (15.0%), cardiovascular events (10.9%), and other secondary extrapulmonary diseases (29.8%). Bilateral lung transplantation is superior to unilateral transplantation (5-year survival rate 57.3% versus 47.4%).

CONCLUSION

Seamless integration of the various components of treatment will be essential for further improvements in outcome. In particular, the follow-up care of transplant recipients should always be provided in close cooperation with the transplant center.

The feasibility of lung transplantation in HIV-seropositive patients

RATIONALE

HIV seropositivity has long been considered a contraindication to lung transplantation, primarily because of the potential risks of added immunosuppression. In the past decade, however, experience with kidney and liver transplantation in the setting of HIV infection, with achievement of satisfactory outcomes, has grown considerably. This promising development has created a need to reconsider this contraindication to lung transplantation.

OBJECTIVES

There is presently limited evidence upon which to base medical decision-making regarding lung transplantation in individuals with HIV infection. In our present study, we wished to extend the existing literature by reporting the outcomes of three individuals with HIV infection who underwent lung transplantation at two centers.

METHODS

We compiled data for a case series of three HIV-infected subjects undergoing lung transplantation at two centers.

MEASUREMENTS AND MAIN RESULTS

We reviewed medical records to investigate the effects of lung transplantation on the course of HIV infection, the development of HIV-related opportunistic infections or malignancies, the occurrence of lung transplant and HIV drug interactions, and the extent of acute rejection. Subject 1, who underwent transplantation for HIV-associated pulmonary arterial hypertension, experienced recalcitrant acute rejection requiring a lymphocyte-depleting agent with subsequent rapid development of bronchiolitis obliterans syndrome. Subjects 2 and 3, who underwent transplantation for idiopathic pulmonary fibrosis, experienced mild acute rejection but remain free from chronic rejection at 4 and 2 years after transplant, respectively.

CONCLUSIONS

Lung transplantation may be feasible for carefully selected patients in the setting of controlled HIV infection. On the basis of our experience with three patients, we caution that acute graft rejection may be more common in such patients.

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.

Pediatric lung transplantation: promise being realized

PURPOSE OF REVIEW

Lung transplantation for infants and children is an accepted but rarely exercised option for the treatment of end-stage lung disease, with outcomes equivalent to those for adults. However, widespread misconceptions regarding pediatric outcomes often confound timely and appropriate referral to specialty centers. We present the updated information for primary pediatricians to utilize when counseling families with children confronted by progressive end-stage pulmonary or cardiovascular disease.

RECENT FINDINGS

We provide general guidelines to consider for referral, and discuss allocation of organs in children, information regarding standard treatment protocols, and survival outcomes.

SUMMARY

Lung transplantation is a worthwhile treatment option to consider in children with end-stage lung disease. The treatment is complex, but lung transplant provides substantial survival benefit and markedly improved quality of life for children and their families. This timely review provides comprehensive information for pediatricians who are considering options for treatment of children with end-stage lung disease.

Cell surface membrane proteins as personalized biomarkers: where we stand and where we are headed

Personalized medicine requires the development of a wide array of biomarker diagnostic assays, reflecting individual variations and thus allowing tailored therapeutic interventions. Membrane proteins comprise approximately 30% of total human proteins; they play a key role in various physiological functions and pathological conditions, although, currently, only a limited number of membrane proteins are applied as biomarkers. In many normal tissues, cell surface membrane proteins are not easily accessible for diagnostic sampling, and tumor-derived membrane preparations - while serving as potential tumor biomarkers - may not reflect physiological protein expression. In addition to post-translational modifications, which may include glycosylation, phosphorylation and lipid modifications, the trafficking of membrane proteins is also regulated. Moreover, a tight cellular quality control monitors membrane protein maturation, and continuous removal and reinsertion, involving special signaling systems, occurs in many cases. However, cell surface membrane proteins already serve as valuable prognostic and predicative biomarkers, for example, in hematological and immunological diseases, by the determination of the cluster of differentiation markers. In this review, we demonstrate the relevance of cell surface membrane biomarkers in various diseases and call attention to the potential application of red blood cell (erythrocyte) membrane proteins in this regard. Surprisingly, red blood cells express hundreds of membrane proteins, which seem to reflect a general genetic and regulatory background, and may serve as relatively stable and easily accessible personalized membrane biomarkers. Quantitative membrane protein detection in red blood cells by flow cytometry may bring a breakthrough in this regard.