Significance of phenotype change after chronic lung allograft dysfunction onset

Biomarkers for Chronic Lung Allograft Dysfunction: Ready for Prime Time?

Chronic lung allograft dysfunction (CLAD) remains a major hurdle impairing lung transplant outcome. Parallel to the better clinical identification and characterization of CLAD and CLAD phenotypes, there is an increasing urge to find adequate biomarkers that could assist in the earlier detection and differential diagnosis of CLAD phenotypes, as well as disease prognostication. The current status and state-of-the-art of biomarker research in CLAD will be discussed with a particular focus on radiological biomarkers or biomarkers found in peripheral tissue, bronchoalveolar lavage' and circulating blood' in which significant progress has been made over the last years. Ultimately, although a growing number of biomarkers are currently being embedded in the follow-up of lung transplant patients, it is clear that one size does not fit all. The future of biomarker research probably lies in the rigorous combination of clinical information with findings in tissue, bronchoalveolar lavage' or blood. Only by doing so, the ultimate goal of biomarker research can be achieved, which is the earlier identification of CLAD before its clinical manifestation. This is desperately needed to improve the prognosis of patients with CLAD after lung transplantation.

Transition from BOS to RAS impairs prognosis after lung transplantation-CLAD subtype analysis by CT volumetry

Background

Chronic lung allograft dysfunction (CLAD), subclassified into bronchiolitis obliterans syndrome (BOS) or restrictive allograft syndrome (RAS), limits survival after lung transplantation. Information concerning transition from BOS to RAS is limited. We aimed to characterize the lung volume change after BOS diagnosis by computed tomography (CT) volumetry and to determine the incidence, risk factors and clinical significance of BOS to RAS transition.

Methods

CT volumetry measurements were performed from 63 patients with CLAD initially classified as BOS by CT volumetry. BOS patients with lung volume remaining >85% of baseline were classified as persistent BOS, whereas BOS patients whose lung volume permanently decreased to ≤85% of baseline were classified as BOS to RAS transition.

Results

During follow-up (median 9.8 years) eight patients (12.7%) were classified as BOS to RAS transition, which decreased recipient (p = 0.004) and graft survival (p = 0.020) in comparison to patients with persistent BOS. Opacities on chest imaging preceded BOS to RAS transition in 88% of patients. Opacities on chest imaging at BOS diagnosis and early CLAD diagnosis after transplantation were risk factors for transition.

Conclusion

Based on lung volume decrease measured by CT volumetry, a small proportion of BOS patients transitioned to RAS which had an adverse effect on recipient and graft survival.

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.