Management of chronic rejection after lung transplantation

Long short-term memory algorithm for personalized tacrolimus dosing: A simple and effective time series forecasting approach post-lung transplantation

BACKGROUND

Management of tacrolimus trough levels (TTLs) influences morbidity and mortality after lung transplantation. Several studies have explored pharmacokinetic and artificial intelligence models to monitor tacrolimus levels. However, many models depend on a wide range of variables, some of which, like genetic polymorphisms, are not commonly tested for in regular clinical practice. This study aimed to verify the efficacy of a novel approach simply utilizing time series data of tacrolimus dosing, with the objective of accurately predicting trough levels in a variety of clinical settings.

METHODS

Data encompassing 36 clinical variables for each patient were gathered, and a multivariate long short-term memory algorithm was applied to forecast subsequent TTLs based on the selected clinical variables. The tool was developed using a dataset of 87,112 data points from 117 patients, and its efficacy was confirmed using 6 additional cases.

RESULTS

Shapley additive explanations revealed a significant correlation between trough levels and prior dose-concentration data. By using simple trend learning of dose, administration route, and previous trough levels of tacrolimus, we could predict values within 30% of the actual values for 88.5% of time points, which facilitated the creation of a tool for simulating TTLs in response to dosage adjustments. The tool exhibited the potential for rectifying clinical misjudgments in a simulation cohort.

CONCLUSIONS

Utilizing our time series forecasting tool, precise prediction of trough levels is attainable independently of other clinical variables through the analysis of historical tacrolimus dose-concentration trends alone.

Impact of reduced mycophenolate exposure on chronic lung allograft dysfunction incidence after lung transplant

Background

Mycophenolate mofetil (MMF) is a key immunosuppression agent for lung transplant recipients (LTR); however, the side effects often lead to dose modifications. Kidney transplant literature has shown reductions in MMF dosing led to an increased incidence of rejection, but data are limited in LTR. The objective was to evaluate the impact of reduced MMF exposure on chronic lung allograft dysfunction (CLAD) in LTR within 36 months of transplant (TXP).

Methods

This single-center, retrospective cohort analyzed LTRs who had an MMF dose reduction or hold ≥7 days between April 1, 2016 and October 31, 2019. LTR who died ≤1 month from TXP were excluded. The primary outcome was incidence of CLAD 36 months from TXP compared to the International Society for Heart and Lung Transplantation (ISHLT) registry data. Secondary outcomes were incidence of treated acute cellular rejection and characterization of MMF dose modifications.

Results

Of 109 patients evaluated, 102 (93.6%) patients had 194 MMF dose modifications within 36 months of TXP, largely due to hematologic toxicities (74.7%). Before modification, 142 (73.2%) were receiving MMF 1,000 mg/day and 52 (26.8%) were receiving 500 mg/day. Incidence of CLAD was 36.4% at 36 months compared to 32.6% reported by ISHLT (p = 0.5216). Incidence of patients with decline in forced expiratory volume in 1 sec ≥10% was 45.1% at 36 months.

Conclusions

In our cohort, most LTRs had an MMF dose modification within 36 months, yet CLAD incidence was consistent with rates reported in the ISHLT Thoracic Organ Transplant Registry. In contrast, more patients demonstrated reduced allograft function compared to post-TXP peak, consistent with "potential" CLAD.

Creating superior lungs for transplantation with next-generation gene therapy during ex vivo lung perfusion

Engineering donor organs to better tolerate the harmful non-immunological and immunological responses inherently related to solid organ transplantation would improve transplant outcomes. Our enhanced knowledge of ischemia-reperfusion injury, alloimmune responses and pathological fibroproliferation after organ transplantation, and the advanced toolkit available for gene therapies, have brought this goal closer to clinical reality. Ex vivo organ perfusion has evolved rapidly especially in the field of lung transplantation, where clinicians routinely use ex vivo lung perfusion (EVLP) to confirm the quality of marginal donor lungs before transplantation, enabling safe transplantation of organs originally considered unusable. EVLP would also be an attractive platform to deliver gene therapies, as treatments could be administered to an isolated organ before transplantation, thereby providing a window for sophisticated organ engineering while minimizing off-target effects to the recipient. Here, we review the status of lung transplant first-generation gene therapies that focus on inducing transgene expression in the target cells. We also highlight recent advances in next-generation gene therapies, that enable gene editing and epigenetic engineering, that could be used to permanently change the donor organ genome and to induce widespread transcriptional gene expression modulation in the donor lung. In a future vision, dedicated organ repair and engineering centers will use gene editing and epigenetic engineering, to not only increase the donor organ pool, but to create superior organs that will function better and longer in the recipient.

Rehabilitative goals for patients undergoing lung retransplantation

Lung retransplantation (LRT) involves a second or subsequent lung transplant (LT) in a patient whose first transplanted graft has failed. LRT is the only treatment option for irreversible lung allograft failure caused by acute graft failure, chronic lung allograft dysfunction, or postoperative complications of bronchial anastomosis. Prehabilitation (rehabilitation before LT), while patients are on the waiting list, is recognized as an essential component of the therapeutic regimen and should be offered throughout the waiting period from the moment of listing until transplantation. LRT is particularly fraught with challenges, and prehabilitation to reduce frailty is one of the few opportunities to address modifiable risk factors (such as functional and motor impairments) in a patient population in which there is clearly room to improve outcomes. Although rehabilitative outcomes and quality of life in patients receiving or awaiting LT have gained increased interest, there is a paucity of data on rehabilitation in patients undergoing LRT. Frailty is one of the few modifiable risk factors of retransplantation that is potentially preventable. As such, it is imperative that professionals involved in the field of retransplantation conduct research specifically exploring rehabilitative techniques and outcomes of value for patients receiving LRT, because this area remains unexplored.

Provider beliefs and practices regarding the management of obesity in lung transplant recipients

Obesity at the time of lung transplant is associated with decreased survival. How providers manage obesity after lung transplantation is unknown. We performed an international survey of lung transplant providers to assess beliefs and practices regarding post-transplant obesity management. Eighty-one providers initiated the survey and 73 (90%) completed the full survey. Respondents were primarily North American-based pulmonary physicians. Nearly all providers believe treating obesity improves quality of life (99%) and survival (95%) after lung transplantation, but that only 41% of patients attempting weight loss are successful. While respondents nearly always recommend diet (96%), exercise (92%), and dietician consultation (89%), they less frequently recommend prescription weight loss medications (29%) or bariatric surgery (11%). Lung transplant providers are motivated to treat obesity in transplant recipients. However, there is a gap between general obesity treatment guidelines and lung transplant practice. Additional training, education, and trials in this population could address this gap.

Mode of action, indications and recommendations on extracorporeal photopheresis (ECP)

Extracorporeal photopheresis (ECP) has gained importance in the treatment of several diseases. Initially introduced as a new therapeutic modality for the treatment of patients with cutaneous T-cell lymphoma, the indications for the use of ECP have expanded to include hematology and transplantation immunology. Extracorporeal photopheresis has found its place in the treatment plan of cutaneous T-cell lymphoma, systemic sclerosis, graft-versus-host disease, organ transplantation such as heart and lung, sometimes as first-line therapy and very often in combination with various systemic immunosuppressive therapies. The procedure basically consists of three steps: leukapheresis, photoactivation and reinfusion. The following article presents possible theories about the mechanism of action, which is not yet fully understood, and discusses the five most common indications for ECP treatment with corresponding therapy recommendations.

Wirkweise, Indikationen und Therapieempfehlungen der extrakorporalen Photopherese (ECP)

Die extrakorporale Photopherese (ECP) hat in jüngster Zeit bei der Behandlung verschiedener Krankheiten an Bedeutung gewonnen. Ursprünglich als neue Therapie zur Behandlung von Patienten mit kutanem T‐Zell‐Lymphom vorgestellt, hat sich der Indikationsbereich für die ECP auf Hämatologie und Transplantationsimmunologie erweitert. Die ECP hat ihren festen Platz im Therapieplan bei kutanen T‐Zell‐Lymphomen, systemischer Sklerose, Graft‐versus‐Host‐Erkrankung, Organtransplantationen wie Herz und Lunge, teilweise als Erstlinientherapie und sehr häufig in Kombination mit verschiedenen systemischen immunsuppressiven Therapien. Das Verfahren besteht im Wesentlichen aus drei Schritten: Leukapherese, Photoaktivierung und Reinfusion. Im folgenden Artikel werden die noch nicht vollständig verstandenen Wirkmechanismen dargestellt, die fünf häufigsten Indikationen für die Behandlung mit ECP diskutiert und Therapieempfehlungen für die jeweilige Indikation gegeben.

Mesenchymal Stromal Cell Therapy in Lung Transplantation

Lung transplantation is often the only viable treatment option for a patient with end-stage lung disease. Lung transplant results have improved substantially over time, but ischemia-reperfusion injury, primary graft dysfunction, acute rejection, and chronic lung allograft dysfunction (CLAD) continue to be significant problems. Mesenchymal stromal cells (MSC) are pluripotent cells that have anti-inflammatory and protective paracrine effects and may be beneficial in solid organ transplantation. Here, we review the experimental studies where MSCs have been used to protect the donor lung against ischemia-reperfusion injury and alloimmune responses, as well as the experimental and clinical studies using MSCs to prevent or treat CLAD. In addition, we outline ex vivo lung perfusion (EVLP) as an optimal platform for donor lung MSC delivery, as well as how the therapeutic potential of MSCs could be further leveraged with genetic engineering.

The healthcare resource utilization and costs of chronic lung allograft dysfunction following lung transplantation in patients with commercial insurance in the United States

AIMS

Chronic lung allograft dysfunction (CLAD), a common complication of lung transplantation, is the leading cause of death for lung transplant recipients. While data on lung transplant costs are available, the impact of CLAD on healthcare resource use (HRU) and cost is not well understood. The primary objective was to quantify the HRU and costs of CLAD in the US using real-world data.

METHODS

A longitudinal retrospective analysis was performed of commercial claims data from the IQVIA PharMetrics Plus database for patients aged 18-64 who underwent lung transplantation between January 1, 2006 and September 30, 2018. Lung transplantation was identified using International Classification of Disease and Common Procedure Terminology procedure codes. Patients studied were observable for at least 12 months before and after transplantation. Patients who developed CLAD were identified using novel, diagnosis codes for incident lung disease at least one year following transplantation. Descriptive analyses were conducted to assess the study's outcomes prior to and following a CLAD diagnosis. All-cause HRU and costs, the study's primary outcomes, leading up to and following CLAD diagnosis were calculated.

RESULTS

Among 129 transplant patients who developed CLAD, healthcare costs were substantially higher in the year following diagnosis ($198,113), compared to the year leading to diagnosis ($85,276). Inpatient admissions were responsible for most costs in years 1 and 2 following diagnosis ($99,372 and $83,348 respectively). Drug costs were higher in the 12 months post-index, compared to the 12 months pre-index ($3,600 vs $2,527).

LIMITATIONS

Claims data do not include clinical data, have limits determining loss of follow-up, and do not provide granularity to determine disease severity. Also, there is no ICD-10-CM code specific to CLAD or BOS.

CONCLUSIONS

CLAD after lung transplant is associated with substantial HRU and costs. Further work is needed to develop interventions that reduce this impact.