Extracorporeal photopheresis to attenuate decline in lung function due to refractory obstructive allograft dysfunction

The use of extracorporeal photopheresis in solid organ transplantation-current status and future directions

Prevention and management of allograft rejection urgently require more effective therapeutic solutions. Current immunosuppressive therapies used in solid organ transplantation, while effective in reducing the risk of acute rejection, are associated with substantial adverse effects. There is, therefore, a need for agents that can provide immunomodulation, supporting graft tolerance, while minimizing the need for immunosuppression. Extracorporeal photopheresis (ECP) is an immunomodulatory therapy currently recommended in international guidelines as an adjunctive treatment for the prevention and management of organ rejection in heart and lung transplantations. This article reviews clinical experience and ongoing research with ECP for organ rejection in heart and lung transplantations, as well as emerging findings in kidney and liver transplantation. ECP, due to its immunomodulatory and immunosuppressive-sparing effects, offers a potential therapeutic option in these settings, particularly in high-risk patients with comorbidities, infectious complications, or malignancies.

A European Multi-Center Analysis of Extracorporeal Photopheresis as Therapy for Chronic Lung Allograft Dysfunction

Extracorporeal photopheresis (ECP) is used by few lung transplant centers to treat chronic lung allograft dysfunction (CLAD). Although reported results suggest a beneficial effect on CLAD progression, evidence is limited to single center experiences. The aim of this study is to analyze outcomes of ECP in a large multicenter European cohort. The primary endpoint was patient survival after initiation of ECP. This study included 631 patients, 87% suffered from bronchiolitis obliterans syndrome (BOS), and 13% had restrictive allograft syndrome (RAS). Long-term stabilization was achieved in 42%, improvement in 9%, and no response in 26%. Within the first 12 months of therapy, 23% of patients died. Patients' survival after initiation of ECP at 5 years was 56% in stable, 70% in responders, and 35% in non-responders (p = 0.001). In multivariable Cox regression, both stabilization (HR: 0.48, CI: 0.27-0.86, p = 0.013) and response (HR: 0.11, CI: 0.04-0.35, p < 0.001) to ECP were associated with survival. Absolute FEV1 at baseline was also protective (HR: 0.09, CI: 0.01-0.94, p = 0.046). RAS phenotype was the only risk factor for mortality (HR: 2.11, 1.16-3.83, p = 0.006). This study provides long-term outcomes of ECP use in CLAD patients in the largest published cohort to date. Two-thirds of the cohort had a sustained response to ECP with excellent long-term results.

Lymphocyte Depleting and Modulating Therapies for Chronic Lung Allograft Dysfunction

Chronic lung rejection, also called chronic lung allograft dysfunction (CLAD), remains the major hurdle limiting long-term survival after lung transplantation, and limited therapeutic options are available to slow the progressive decline in lung function. Most interventions are only temporarily effective in stabilizing the loss of or modestly improving lung function, with disease progression resuming over time in the majority of patients. Therefore, identification of effective treatments that prevent the onset or halt progression of CLAD is urgently needed. As a key effector cell in its pathophysiology, lymphocytes have been considered a therapeutic target in CLAD. The aim of this review is to evaluate the use and efficacy of lymphocyte depleting and immunomodulating therapies in progressive CLAD beyond usual maintenance immunosuppressive strategies. Modalities used include anti-thymocyte globulin, alemtuzumab, methotrexate, cyclophosphamide, total lymphoid irradiation, and extracorporeal photopheresis, and to explore possible future strategies. When considering both efficacy and risk of side effects, extracorporeal photopheresis, anti-thymocyte globulin and total lymphoid irradiation appear to offer the best treatment options currently available for progressive CLAD patients. SIGNIFICANCE STATEMENT: Effective treatments to prevent the onset and progression of chronic lung rejection after lung transplantation are still a major shortcoming. Based on existing data to date, considering both efficacy and risk of side effects, extracorporeal photopheresis, anti-thymocyte globulin, and total lymphoid irradiation are currently the most viable second-line treatment options. However, it is important to note that interpretation of most results is hampered by the lack of randomized controlled trials.

Clinical course of SARS-CoV-2 infection and recovery in lung transplant recipients

BACKGROUND

Reports on outcomes following severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in lung transplant recipients remain limited.

METHODS

We performed a single-center, observational study of outcomes in lung transplant recipients diagnosed with SARS-CoV-2 between 5/1/2020 and 3/15/2022 that were followed for a median of 123 days. We analyzed changes in spirometry, acute lung allograft dysfunction (ALAD) incidence, hospitalization, mechanical ventilation needs, secondary infection, and survival.

RESULTS

In our cohort of 336 patients, 103 developed coronavirus disease (COVID) (27 pre-Delta, 20 Delta, and 56 Omicron-era). Twenty-five patients (24%) required hospitalization and 10 patients ultimately died (10%). Among 85 survivors who completed ambulatory spirometry, COVID-19 did not alter change in forced expiratory volume in 1 s (FEV1 ) or forced vital capacity (FVC) over time compared to the preceding 6 months. The pre-COVID FEV1 change was -0.05 ml/day (IQR -0.50 to 0.60) compared to -0.20 ml/day (IQR -1.40 to 0.70) post-COVID (p = .16). The pre-COVID change in FVC was 0.20 ml/day (IQR -0.60 to 0.70) compared to 0.05 ml/day (IQR -1.00 to 1.10) post-COVID (p = .76). Although the cohort overall had stable lung function, 33 patients (39%) developed ALAD or accelerated chronic lung allograft dysfunction (FEV1 decline >10% from pre-COVID baseline). Nine patients (35%) with ALAD recovered lung function. Within 3 months of acute COVID infection, 18 patients (17%) developed secondary infections, the majority being bacterial pneumonia. Finally, vaccination with at least two doses of mRNA vaccine was not associated with improved outcomes.

CONCLUSIONS

This study describes the natural history of SARS-CoV-2 infection in a large cohort of lung transplant recipients. Although one third of patients develop ALAD requiring augmented immunosuppression, infection with SARS-CoV-2 is not associated with worsening lung function.

Assessing treatment outcomes in CLAD: The Hannover-extracorporeal photopheresis model

BACKGROUND

Chronic lung allograft dysfunction (CLAD) is a leading cause of graft loss in lung transplantation. Despite this, convincing treatment data is lacking, and protocols vary widely between centers. CLAD phenotypes exist, but phenotype transitioning has increased the challenge of designing clinically relevant studies. Extracorporeal photopheresis (ECP) has long been a suggested salvage treatment, but efficacy appears unpredictable. This study describes our experiences with photopheresis, using novel temporal phenotyping to illustrate the clinical course.

METHODS

Retrospective analysis of patients completing ≥3 months of ECP for CLAD between 2007 and 2022 was performed. A latent class analysis employing a mixed-effects model was performed, deriving patient subgroups based on spirometry trajectory over the 12 months prior to photopheresis until graft loss or 4 years post photopheresis initiation. The resulting temporal phenotypes were compared in terms of treatment response and survival outcomes. Linear discriminatory analysis was used to assess phenotype predictability, relying solely on data available at photopheresis initiation.

RESULTS

Data from 5,169 outpatient attendances in 373 patients was used to construct the model. Five trajectories were identified, with uniform spirometry changes evident following 6 months of photopheresis. Outcomes were poorest in Fulminant patients (N = 25, 7%) with median survival of 1 year. In the remainder, poorer lung function at initiation led to poorer outcomes. The analysis revealed important confounders, affecting both decision-making and outcome interpretation.

CONCLUSIONS

Temporal phenotyping provided novel insights into ECP treatment response in CLAD, particularly the importance of timely intervention. Limitations in % Baseline values in guiding treatment decisions warrant further analysis. Photopheresis may have a more uniform effect than previously thought. Predicting survival at ECP initiation appears feasible.

Mechanisms of Action of Extracorporeal Photopheresis in the Control of Bronchiolitis Obliterans Syndrome (BOS): Involvement of Circulating miRNAs

Clinical evidence suggests an improvement or stabilization of lung function in a fraction of patients with bronchiolitis obliterans syndrome (BOS) treated by extracorporeal photopheresis (ECP); however, few studies have explored the epigenetic and molecular regulation of this therapy. The aim of present study was to evaluate whether a specific set of miRNAs were significantly regulated by ECP. Total RNA was isolated from serum of patients with established BOS grade 1–2 prior to the start and after 6 months of ECP treatment. We observed a significant downregulation of circulating hsa-miR-155-5p, hsa-miR-146a-5p and hsa-miR-31-5p in BOS patients at the start of ECP when compared to healthy subjects. In responders, increased miR-155-5p and decreased miR-23b-3p expression levels at 6 months were found. SMAD4 mRNA was found to be a common target of these two miRNAs in prediction pathways analysis, and a significant downregulation was found at 6 months in PBMCs of a subgroup of ECP-treated patients. According to previous evidence, the upregulation of miR-155 might be correlated with a pro-tolerogenic modulation of the immune system. Our analysis also suggests that SMAD4 might be a possible target for miR-155-5p. Further longitudinal studies are needed to address the possible role of miR-155 and its downstream targets.