ISHLT2022 Roving Reporters – Reports from Advanced Lung Failure and Transplantation

Saturday, 30 April, 2022

Animal models could be used to study the processes and investigate underlying mechanisms and therapeutic interventions of lung transplant disease pathogenesis. A variety of lung transplant models was reviewed and discussed in this session on how we can use animal models to improve our understanding of lung transplant pathophysiology.

Rat Models: A Window of Opportunity
Dong Tian, MD
, The University of Tokyo Graduate School of Medicine, Tokyo, Japan
The ideal animal should be able to provide physiological and anatomical similarities to the human disease process. It should be cost-efficient, technically stable, and easy to handle. The rat model was first developed in 1971 and has since been used to study several lung transplantation models. The advantages of the rat model include weight and size, which allows one performer to develop the model compared to larger animals. Complicated techniques such as EVLP and re-transplantation can be applied in the rat model, and serial blood sampling is more feasible in rats, compared to the mice model (researchers are able to obtain more blood from rats).

Another advantage of the rat model is low surgical complexity. There is no technical difficulty in heterotypic or orthotropic tracheal or bronchial implantation. Orthotopic left lung transplantation can be done by Dr. Tian’s group’s “Pendulum” model within 48 minutes without intraoperative failing. The cost of the rat model is cheap, and this is helpful when trying to screen novel treatments prior to proceeding to large animal models.

The short gestation period and life span of rats also allows investigators to increase sample size in a short timeframe, which increases the replicative value in research, leading to more robust and credible results. A rat model has been used to develop a model to study ischemia-reperfusion injury, allograft rejection, ex vivo lung perfusion, and decellularization (bioartificial lung).

Mouse Models: The Golden Standard?
Andrew E. Gelman, PhD
, Washington University School of Medicine, St. Louis, MO USA
Dr. Gelman discussed the murine model in lung transplantation in this session. The mice model has been used in lung transplantation research due to the similarity of general anatomic organization of human and mouse lungs, the cost-effectiveness of the model, and the opportunities to investigate genetic manipulations.

The first model using mice (heterotrophic tracheal transplantation) was developed in 1993 by a group of investigators at the University of Minnesota. This model produces a histopathological appearance of obliterative bronchiolitis in seven days, and continues to be a highly used BOS model due to technical ease. The drawback of this model is that the airway was not vascularized, and there is a lot of immunologic stress.

Orthotopic tracheal transplantation from a mice model was developed at Mount Sinai in 2002 with an end-to-end anastomosis. This model demonstrates a loss of ciliated cells and high amounts of lymphocyte infiltrate by three weeks, and subbasement fibrosis by four weeks. The drawback of this model is allografts undergo recipient-derived re-epithelialization, which does not happen in humans.

Orthotopic lung transplantation was developed in 2006 at Washington University. It is technically challenging and took about six months to learn. It has been used to study PGD, ACR, AMR, and CLAD. There are several drawbacks of the mice model. The regenerative response to lung tissue injury is prominent in this model. Mice have a different spatial distribution of club cells, and immune system dissimilarities. Finally, an altered microbiome and sterile facility housing can alter the immune response.

Xenotransplantation and Beyond
Megan Sykes, III, MD
, Columbia Center for Translational Immunology, Columbia, NY USA
Xenotransplantation is transplantation from another species. It could provide unlimited organ supply, alleviate organ shortages, and allow transplants to be performed electively as there is no need to wait for donors. Organ survival in xenotransplantation has improved since the 1980s from minutes to months due to better immunosuppression.

There are three major approaches to overcoming immune barriers to xenograft: immunosuppression, genetic engineering, and tolerance. Recent studies showed that the survival time of xenotransplantation of a heart from pigs to non-human primates lasted for about six months. In 2021, that has been prolonged to nine months by using an organ from genetic modification “10-GE pig,” including growth hormone receptor knockout. This is the same approach that lead to the first pig to human heart transplantation that was performed recently in the United States.

For lung and liver xenotransplantation, the graft survival was only two and four weeks, respectively. Tolerance is necessary to get permanent graft survival without excess immunosuppression. There are two approaches for xenograft tolerance: mixed chimerism and thymic transplantation. Mixed chimerism involves the coexistence of donor and recipient hematopoietic systems. It can tolerate most of the immune system (T cell, B cell, and partial NK cell tolerance). The second technique of xenograft tolerance is thymic transplantation. The combination of these two techniques using further genetic modification could make xenotolerance clinically achievable and safe.

The Ex-Vivo Lung as an Experimental Mechanistic Model of Transplant
Ciara Shaver, MD, PhD
, Vanderbilt University Medical Center, Nashville, TN USA
Ex vivo lung perfusion (EVLP) provides a platform for transcriptomic, proteomic, and metabolic assessment of potential donor lungs. Moreover, advanced assessment can be performed in EVLP to evaluate gas exchange, biomarkers, and imaging studies. The possible disadvantages are variability between lungs (especially if using declined donor lungs), limited duration, and logistic challenges. EVLP with declined human donor lungs is a useful tool for mechanistic research.

Injury can be induced in this model by either intravenous or intrabronchial instillation by infectious or sterile insults, and injury can be detected within two hours. This model can test the causal roles of molecules and pathways. However, the current EVLP systems are limited by 6-8 hours due to mitochondrial injury, altered glucose utilization, impaired amino acid clearance, and shift in lipid utilization. Bioenergetic and metabolic support is limited to 6-12 hours and is associated with lung health deterioration. Temperature management and xenogeneic platforms may facilitate organ recovery and rehabilitation.

Clinical Interventions with Ex-Vivo Perfused Lungs
Marcelo Cypel, MD
, Toronto General Hospital, Toronto, ON Canada
Dr. Cypel reviewed existing evidence for EVLP therapeutic interventions, and covered novel interventions in EVLP. EVLP allows the transplant team to assess and optimize organs prior to transplantation. The conditions of organs that could be optimized by EVLP include pulmonary edema, pneumonia, aspiration, chronic viral infection (HCV), or long warm ischemia in controlled and uncontrolled DCD.

Treatment strategies that have been studied in EVLP are perfusion therapy (solution with UVC light for HCV treatment, Rituximab for EBV infection), drugs (high dose antibiotics to reduce bacteria), inhaled gases (high dose inhaled nitric oxide above 200 ppm acts as an antimicrobial through nitrosylation of bacterial chromosome), cell therapy, immuno-cloaking, and gene therapy (conversion human donor blood type ex vivo).

In the future, EVLP could be a platform for major advances in organ transplantation including cell and genetic modification, organ modification in xenotransplantation, and a platform for patients’ own organ repair.

How Well Do Animal Models Mimic the Human Condition?
Fiorella Calabrese, MD
, University of Padova, Padova, Italy
Dr. Calabrese concluded the session with things we should consider when using animal models to conduct a study on lung transplantation. The ideal animal model should provide strong physiological/anatomical similarity to a human disease process.

Unfortunately, the ideal model does not exist yet. Investigators should know the lung anatomy of animal models, which animal (small, large, genetically modified) is suitable for which disease pathologies, and graft pathology lesions. In conclusion, there is no perfect animal model and continuous effort should be made to collect translatable data to select an appropriate model.
– Summary by Prangthip Charoenpong, MD, MPH

The effect of COVID-19 on lung transplant patients remains an intense research focus. In this abstract session, presenters discussed the use of lung transplant for COVID-19 fibrosis, findings from COVID-19 explants, the effect of COVID-19 on transplant function, and continued discussions regarding the effectiveness of COVID vaccination.

First, Donna K. Phan, MD, MPH, of Montefiore Medical Center in New York, NY USA presented the experience in the United States of the use of lung transplant for COVID-19 fibrosis. Broadly, outcomes in this cohort are limited due to the time period since COVID-19 has existed, but they were able to extract 30-day mortality, length of stay, and adverse events. Reviewing the UNOS/OPTN database from Jan 2018 through July 2021 and comparing COVID fibrosis patients to patients with IPF, individuals transplanted for COVID-19 were: younger, more likely to get a bilateral transplant, three times more likely to be Hispanic, and had shorter times on the waitlist with a higher allocation score. Most notably, the IPF vs COVID-19 cohorts had no significant differences in 30-day mortality and hospital length of stay.

Moving forward to autopsy studies of COVID-19 lungs, Sravanthi Nandavaram, MD, of the University of Kentucky in Lexington, KY USA described the damage that is caused by the viral infection as diffuse alveolar damage that is heterogeneous with organizing pneumonia, pulmonary hemorrhage, and microthrombi. Alveolar capillary microthrombi are 9x more prevalent in COVID ARDS than in influenza ARDS. Looking at a cohort of COVID-19 patients, most had traction bronchiectasis (84%) and consolidations (80%) on CT imaging, and on pathology had NSIP (76%), pulmonary vascular injury (72%), and alveolar hemorrhage (56%).

Thinking now of lung transplant patients who developed COVID19, Elizabeth Roosma, MD, of Martini Ziekenhuis in Groningen, Netherlands, described a review of 74 COVID-19 lung transplant recipients and their outcomes. Out of their cohort, 57% were hospitalized, 45% in the ICU, and 64% survived (overall mortality 20%). Of those were not hospitalized for their disease, mortality was 0%. Long term, they noted that FEV1/FVC was significantly decreased at three and six months, but there was no significant difference in hospitalized vs non-hospitalized patients. Finally, they did note a trend towards higher mortality in transplant recipients with pre-existing CLAD.

Next, Gaelle Dauriat, MD, from Marie Lannelongue Hospital in Le Plessis Robinson, France, presented the French experience with vaccine response in lung transplant recipients, including Pfizer, Moderna, and AstraZeneca vaccines. Their primary outcome was to determine the proportion of patients with a protective level of antibody, with a secondary outcome to determine the proportion of patients with COVID-19 infection and severity of disease. They noted four factors are associated with vaccine response: younger, delay between transplant and vaccination, not being on steroids or MMF. Interestingly, they noted no difference in COVID-19 infection or severity in vaccine responders vs non-responders.

An additional factor for determining vaccine responsiveness may be the level of torque tenoviremia. Erik Verschuuren, MD, PhD, of UMC Groningen Transplant Center in Groningen, Netherlands, presented his work on this subject. Torque tenovirus (TTV) load has previously been described as a directly related marker for level of immunosuppression. In their study of 103 transplant patients receiving the Moderna COVID-19 vaccine, the TTV load did have a correlation with vaccine response, contributing to known data.
– Summary by Grant Turner, MD

The United States Experience of Lung Transplantation in Recipients with COVID-19 Fibrosis: A UNOS/OPTN Analysis
Donna K. Phan, MD, MPH, Montefiore Medical Center, Albert Einstein School of Medicine, Bronx, NY USA

Radiographic and Histopathologic Lessons from COVID-19 Explants
Sravanthi Nandavaram, MD, University of Kentucky, Lexington, KY USA

The Effect of COVID-19 Infection on Transplant Function and Development of CLAD in Lung Transplant Patients: A Multicenter Experience
Elizabeth Roosma, MD, Martini Ziekenhuis, Groningen, Netherlands

SARS‐CoV‐2 Vaccine Response in Lung Transplant Recipients: A French Multicenter Study
Gaelle Dauriat, MD, Marie Lannelongue Hospital, Le Plessis Robinson, France

TTV Load is Associated with SARS-CoV-2 Vaccination Response in Lung Transplant Recipients
Erik A.M. Verschuuren, MD, PhD, UMC Groningen Transplant Center, University of Groningen, Groningen, Netherlands

Variances in Humoral Responses to Different Spike Protein Domains After SARS-CoV-2 Vaccination in Lung and Heart Transplant Recipients
Jasper Sauer, Medical School Hannover, Hannover, Germany
Treatment of De Novo DSA with IVIG Monotherapy After Lung Transplantation
Skye J. Castaneda, PharmD, Spectrum Health, Grand Rapids, MI USA
De novo donor-specific anti-HLA antibodies (DSA) increase the risk of CLAD and decrease survival. This study aimed to evaluate IVIG monotherapy for de novo DSA without allograft dysfunction or clinical antibody-mediated rejection (AMR). This is a retrospective study that included 32 lung transplant recipients who were treated with IVIG for de novo DSA with no evidence of AMR. Of 32 patients, 18 patients cleared de novo DSA (defined as sum MFI < 1,000) and 14 patients did not clear at the end of IVIG therapy. There was no significant difference in baseline characteristic, transplant indication or type, cPRA, HLA mismatch, or PGD. There was no difference in CLAD or survival. However, ACR and AMR tended to be more frequent during follow-up in the group that did not clear de novo DSA.

Carfilzomib versus Rituximab for Treatment of De Novo Donor Specific Antibodies in Lung Transplant Recipients
Deepika Razia, MBBS, Norton Thoracic Institute, St. Joseph’s Hospital and Medical Center, Phoenix, AZ USA
De novo donor-specific antibodies (DSA) increase risk of ACR, AMR, and CLAD in lung transplant recipients. Carfilzomib (CFZ) and rituximab (RTX) can lower the mean fluorescent intensity (MFI) of DSA. This study aimed to compare the degree and duration of DSA depletion with carfilzomib (CFZ) and rituximab (RTX). Forty-four lung transplant recipients with 53 drug events were identified and divided into two groups, CFZ (n=17) and RTX (n=36). Both CFZ and RTX were shown to significantly lower the MFI at DQ locus. The median of change in MFI was comparable. However, the median interval to DSA rebound was shorter in CFZ group. CLAD-free survival was comparable in the 2 groups.

Efficacy and Safety of the Janus Kinase 1 Inhibitor Itacitinib (ITA) in Patients with Bronchiolitis Obliterans (BOS) Syndrome Following Double Lung Transplant
Joshua M. Diamond, MD, MSCE, University of Pennsylvania, Philadelphia, PA USA
This study aimed to evaluate the efficacy and safety of the Janus Kinase 1 inhibitor ITA in patients with BOS after lung transplantation. This is an open-label, phase 1/2 randomized control trial to evaluate three doses of ITA in adult lung transplant recipients with a diagnosis of BOS stage 1-3 in the past year.

Twenty-three patients were randomized to take ITA 300 mg BID (n=7), 400 mg QD (n=7), 600 mg QD (n=8), or 200 mg QD (n=1, enrolled under previous protocol version). There was no difference in baseline characteristics. Mean FEV1 was 1.61 L at study enrollment across all doses of ITA (n=23). No clear dose-related trends were seen; therefore, results are reported as pooled across all doses.

Post-enrollment mean FEV1 increased at subsequent time points (1.69 L at week 4, 1.76 L at week 8, 1.86 L at week 12). Protocol-defined FEV1 response was observed in 5 patients (21.7%). The overall incidence of treatment-emergent adverse events (AEs) was similar across all doses (87.0%). The most common AEs were cytomegalovirus (CMV) reactivation/viremia, diarrhea, and fatigue. Infections of any cause occurred in 14 patients (60.9%).

In conclusion, lung function stabilized or improved in a subset of BOS patients who were treated with ITA. Although AEs were frequent, they were generally not dose-limiting.

An Investigational Inhaled rhIL-1Ra (ALTA-2530) Demonstrates Distribution to Distal Regions of Lung and High Affinity IL-1 Receptor Blockade Supporting Development as a Treatment for Bronchiolitis Obliterans Syndrome
Michelle Palacios, PhD, Altavant Sciences, Cary, NC USA
Dysregulated expression of interleukin-1 (IL-1), and downstream cytokines, has been shown to involve in the development of bronchiolitis obliterans syndrome (BOS). Blocking the IL-1 receptor type 1 (IL-1R1) is proposed to reestablish the physiologic immune regulation. The aim of this study was to assess potency and characterize distribution of ALTA-2530 in the lung in the animal model (rat and non-human primate).

ALTA-2530 is inhaled from of a recombinant human IL-1Ra (rhIL-1Ra) that binds competitively to IL-1R1 to block signaling of IL-1a/IL-1b. Bronchoalveolar lavage fluid (BALF) and lung tissue samples were collected from rats and non-human primates after seven daily inhaled doses of ALTA-2530.

The study showed that a daily dose of ALTA-2530 provided more than 24-hour exposure in BALF. The nebulized form of ALTA 2530 achieved delivery of IL-1Ra to dial parts despite narrow airway. The affinity of IL-1Ra bound to IL-1R1 with over 100 times greater affinity than endogenous IL-1 agonists IL-1a. Inhaled ALTA-2530 distributes to distal regions of the lung and inhibits downstream signaling which is supportive of therapy for BOS.

Long-Term Pirfenidone for Restrictive Allograft Syndrome: A Case Series
Hanne Beeckmans, MD, KU Leuven, Leuven, Belgium
The study aimed to report the outcomes of restrictive allograft syndrome (RAS) patients treated with off-label pirfenidone (PFD). The investigators identified four of 30 patients RAS patients who were on long-term PFD—mean duration of 5.2±1.1 years (range 3.8-6.3 years).

Three out of 4 are currently alive (total follow-up was 10.4±3.1 years). The survival post-RAS diagnosis was 6 years (4.9-7.6). FVC and FEV1 did not significantly change during PFR treatment. TLC and DLCO did not significantly differ over time. PFD may attenuate PFT decline in RAS patients.

Extracorporeal Photopheresis in CLAD: A 15-Year Single Centre Experience
Mark Greer, MB Bch, Hanover Medical School, Hanover, Germany
In this study, the investigators summarized their experience of using extracorporeal photopheresis (ECP) in chronic lung allograft dysfunction (CLAD) over 25 years at their center and assess the outcomes and determining treatment duration. A total of 372 patients who received ECP for CLAD were included in the analysis. The investigators used latent class mixed effect models to identify the phenotype of treatment response.

There was a total of 5 classes (easy, intermediate, advanced progressive, advanced chronic, fulminant). Twenty-five patients (7%) were in the fulminant group, which did not respond to treatment. In advanced groups (progressive and chronic), patients were older and had underperforming grafts. Survival of these three groups (fulminant, advanced progressive, and advanced chronic groups) was worse compared to the other two groups (early and intermediate). ECP appears to offer a survival benefit in some CLAD phenotypes.
– Summary by Prangthip Charoenpong, MD, MPH