Increased Calculated Panel Reactive Antigen Is Associated With Increased Waitlist Time and Mortality in Lung Transplantation

The Impact of Prelung Transplant HLA Antibodies on Post-transplant Outcomes in Recipients With Autoimmune Lung Disease

INTRODUCTION

Patients with advanced lung disease who have HLA antibodies against potential donors have reduced opportunities for transplant. Not all HLA antibodies, however, have the same impact on post-transplant outcomes. It is unknown whether HLA antibodies arising in the context of autoimmune lung disease are associated with increased antibody mediated rejection (AMR) or bronchiolitis obliterans stage 1 (BOS1)-free survival.

METHODS

This study used retrospective data from SRTR to examine BOS1-free survival and AMR among sensitized recipients with autoimmune ILD compared to sensitization recipients with nonautoimmune ILD, accounting for other sources of sensitization such as pregnancy and blood transfusions. This study did not use organs from prisoners and participants were neither coerced nor paid.

RESULTS

Sensitized recipients with autoimmune ILD did not have differences in BOS1-free survival when adjusting for sensitizing exposures (HR = 0.90, 95% CI: 0.70-1.16) or clinical covariates (HR = 0.96, 95% CI: 0.83-1.12). There was also no difference in AMR (OR = 1.92, 95% CI: 1.04-3.52).

CONCLUSIONS

HLA antibodies arising in the context of autoimmune ILD do not appear to have a differential impact on BOS1-free survival or AMR. This provides further evidence that patients sensitized via autoimmune lung diseases do not require separate decision-making regarding HLA antibody status compared to the overall sensitized population.

Intravenous Immunoglobulins Alone for the Desensitization of Lung Transplant Recipients with Preformed Donor Specific Antibodies and Negative Flow Cytometry Crossmatch

BACKGROUND

The lack of evidence regarding optimal desensitization strategies for lung transplant candidates with preformed donor specific anti-human leukocyte antigen antibodies (DSAs) has led to varying approaches among centers towards this patient group. Our institution's desensitization protocol for recipients with preformed DSAs and negative flow cytometry crossmatch (FCXM) consists of intravenous immunoglobulin (IVIG) as the sole therapy. The study aimed to determine outcomes using this approach.

METHODS

This retrospective study included adults who underwent lung-only transplantation for the first time between January 2015 and March 2022 at a single center. We excluded patients with positive or missing FCXM results. Transplant recipients with any DSA ≥ 1000 MFI on latest testing within three months of transplant were considered DSA-positive, while recipients with DSAs <1000 MFI and those without DSAs were assigned to the low-level/negative group. Graft survival (time to death/retransplantation) and chronic lung allograft dysfunction (CLAD)-free times were compared between groups using Cox proportional hazards models.

RESULTS

Thirty-six out of 167 eligible patients (22%) were DSA-positive. At least 50% of preformed DSAs had documented clearance (decrease to <1000 MFI) within the first 6 months of transplant. Multivariable Cox regression analyses did not detect a significantly increased risk of graft failure (aHR 1.04 95%CI 0.55-1.97) or chronic lung allograft dysfunction (aHR 0.71 95%CI 0.34-1.52) in DSA-positive patients compared to patients with low-level/negative DSAs. Incidences of antibody-mediated rejection (p = 1.00) and serious thromboembolic events (p = 0.63) did not differ between study groups.

CONCLUSION

We describe a single-center experience of administering IVIG alone to lung transplant recipients with preformed DSAs and negative FCXM. Further studies are required to confirm the efficacy of this strategy against other protocols.

Outcomes of listing for lung and heart-lung transplantation in pulmonary hypertension: comparative experience in France and the UK

Background

Lung or heart-lung transplantation (LT/HLT) for severe pulmonary hypertension (PH) as the primary disease indication carries a high risk of waiting list mortality and post-transplant complications. France and the UK both have coordinated PH patient services but with different referral pathways for accessing LT services.

Methods

We conducted a comparative analysis of adult PH patients listed for LT/HLT in the UK and France.

Results

We included 211 PH patients in France (2006-2018) and 170 in the UK (2010-2019). Cumulative incidence of transplant, delisting and waiting list death within 3 years were 81%, 4% and 11% in France versus 58%, 10% and 15% in the UK (p<0.001 for transplant and delisting; p=0.1 for death). Median non-priority waiting time was 45 days in France versus 165 days in the UK (p<0.001). High-priority listing occurred in 54% and 51% of transplanted patients respectively in France and the UK (p=0.8). Factors associated with achieving transplantation related to recipients' height, male sex, clinical severity and priority listing status. 1-year post-transplant survival was 78% in France and 72% in the UK (p= 0.04).

Conclusion

Access to transplantation for PH patients is better in France than in the UK where more patients were delisted due to clinical deterioration because of longer waiting time. High rates of priority listing occurred in both countries. Survival for those achieving transplantation was slightly better in France. Ensuring optimal outcomes after transplant listing for PH patients is challenging and may involve early listing of higher risk patients, increasing donor lung utilisation and improving allocation rules for these specific patients.

The Highly Sensitized Recipient: Pretransplant and Posttransplant Considerations

Highly sensitized patients, who are often black and Hispanic women, are less likely to be listed for lung transplant and are at higher risk for prolonged waitlist time and waitlist death. In this review, the authors discuss strategies for improving access to transplant in this population, including risk stratification of crossing pretransplant donor-specific antibodies, based on antibody characteristics. The authors also review institutional protocols, such as perioperative desensitization, for tailoring transplant immunosuppression in the highly sensitized population. The authors conclude with suggestions for future research, including development of novel donor-specific antibody-directed therapeutics.

Safety of Crossing Donor-specific Antibodies in Lung Transplantation

BACKGROUND

Donor-specific antibodies (DSAs) have been associated with antibody-mediated rejection, chronic lung allograft dysfunction (CLAD), and increased mortality in lung transplant recipients. Our center performs transplants in the presence of DSA, and we sought to evaluate the safety of this practice with respect to graft loss, CLAD onset, and primary graft dysfunction (PGD).

METHODS

We reviewed recipients transplanted from 2010 to 2017, classifying them as DSA positive (DSA+) or negative. We used Kaplan-Meier estimation to test the association between DSA status and time to death or retransplant and time to CLAD onset. We further tested associations with severe PGD and rejection in the first year using logistic regression and Fisher exact testing.

RESULTS

Three hundred thirteen patients met inclusion criteria, 30 (10%) of whom were DSA+. DSA+ patients were more likely to be female, bridged to transplant, and receive induction therapy. There was no association between DSA status and time to death or retransplant (log rank P = 0.581) nor death-censored time to CLAD onset (log rank P = 0.278), but DSA+ patients were at increased risk of severe PGD (odds ratio 2.88; 95% confidence interval, 1.10-7.29; P = 0.031) and more frequent antibody-mediated rejection in the first posttransplant year.

CONCLUSIONS

Crossing DSA at time of lung transplant was not associated with an increased risk of death or CLAD in our cohort, but patients developed severe PGD and antibody-mediated rejection more frequently. However, these risks are likely manageable when balanced against the benefits of expanded access for sensitized candidates.

Place-based heterogeneity in lung transplant recipient outcomes

Place is defined as a social or environmental area of residence with meaning to a patient. We hypothesize there is an association between place and the clinical outcomes of lung transplant recipients in the United States. In a retrospective cohort study of transplants between January 1, 2010, and December 31, 2019, in the Scientific Registry of Transplant Recipients, multivariable Cox regression models were used to test the association between place (through social and environmental factors) with readmission, lung rejection, and survival. Among 18,465 recipients, only 20% resided in the same county as the transplant center. Recipients from the most socially vulnerable counties when compared to the least vulnerable were more likely to have COPD as a native disease, Black or African American race, and travel long distances to reach a transplant center. Higher local life expectancy was associated with lower likelihood for readmission (odds ratio [OR] = 0.90, 95% confidence interval [CI]: 0.84, 0.98, p = .01). Higher social vulnerability was associated with a higher likelihood of lung rejection (OR = 1.37, [CI]: 1.07, 1.76, p = .01). There was no association of residence with posttransplant survival. Recipient place-based factors were associated with complications and processes of care after transplant and warrant further investigation.

Human leukocyte antigen antibody sensitization, lung transplantation, and health equity

Women with advanced lung disease, particularly Black and Hispanic women, are more likely than other patients to have anti-human leukocyte (HLA) antibodies against potential donors. Sensitized patients, especially those who are highly sensitized, are less likely to be listed for lung transplant or to be considered candidates for mechanical circulatory support. They are also at higher risk for waitlist death. Institutional variability in approach to HLA antibody screening and pre-transplant management creates barriers to transplant that disproportionately impact Black and Hispanic women. At the same time, our understanding of the clinical significance of pre-transplant antibodies lags behind the sophistication of our screening assays. The lack of national data on pre- and post-transplant HLA antibody characteristics hinders research into strategies to mitigate concerns about these antibodies and to improve access to lung transplant among sensitized patients. Ongoing work should be done to identify clinically higher risk antibodies, to develop better strategies for safely crossing antibodies at the time of transplant, and to model changes in lung allocation to give priority to sensitized patients for a HLA antibody-antigen compatible donors. These priorities mandate a commitment to collaborative, multicenter research and to real time translation of results to clinical practice and allocation policy.

The impact of HLA-DR mismatch status on retransplant-free survival and bronchiolitis obliterans syndrome‒free survival among sensitized lung transplant recipients

INTRODUCTION

Donor‒recipient HLA-DR locus matching may be protective against bronchiolitis obliterans syndrome (BOS) in lung transplant recipients. It is unknown whether this benefit is more significant among sensitized (calculated panel reactive antibodies (CPRAs) of >0%) and highly sensitized (CPRAs of ≥80%) recipients who may be at a higher risk for BOS.

METHODS

This was a retrospective cohort study of adults in the Scientific Registry of Transplant Recipients who underwent lung transplantation between May 5, 2005 and May 31, 2019. Retransplant-free survival and BOS-free survival were compared among recipients with 0 vs ≥1 DR mismatches, grouped according to sensitization.

RESULTS

Among all 20,355 included recipients, 0 DR mismatch status was associated with improved retransplant-free survival (hazard ratio [HR] = 0.83, 95% CI = 0.74-0.93, p = 0.002) and BOS-free survival (HR = 0.86, 95% CI = 0.77-0.96, p = 0.007). Among sensitized recipients, 0 DR mismatch status was also associated with improved retransplant-free survival (HR = 0.79, 95% CI = 0.65-0.97, p = 0.02) and BOS-free survival (HR = 0.82, 95% CI = 0.67-1.00, p = 0.04). There was however no difference in retransplant-free or BOS-free survival between sensitized and non-sensitized recipients with 0 DR mismatches. Among highly sensitized recipients, 0 DR mismatch status was not associated with retransplant-free or BOS-free survival. Among sensitized and highly sensitized recipients, 0 DR mismatch status was not associated with reduced use of plasmapheresis or reduced biopsy-proven, treated acute cellular rejection compared with non-sensitized recipients.

CONCLUSIONS

HLA-DR matching is associated with a similar improvement in retransplant-free and BOS-free survival among non-sensitized and sensitized lung transplant recipients. DR matching does not confer a more substantial retransplant-free or BOS-free survival benefit to highly sensitized recipients than to non-sensitized recipients.

Lung transplant waitlist outcomes in the United States and patient travel distance

There is a broad range of patient travel distances to reach a lung transplant hospital in the United States. Whether patient travel distance is associated with waitlist outcomes is unknown. We present a cohort study of patients listed between January 1, 2006 and May 31, 2017 using the Scientific Registry of Transplant Recipients. Travel distance was measured from the patient's permanent zip code to the transplant hospital using shared access signature URL access to Google Maps, and assessed using multivariable competing risk regression models. There were 22 958 patients who met inclusion criteria. Median travel distance was 69.7 miles. Among patients who traveled > 60 miles, 41.2% bypassed a closer hospital and sought listing at a more distant hospital. In the adjusted models, when compared to patients who traveled ≤60 miles, patients who traveled >360 miles had a 27% lower subhazard ratio (SHR) for waitlist removal (SHR 0.73, 95% confidence interval [CI]: 0.60, 0.89, P = .002), 16% lower subhazard for waitlist death (SHR 0.84; 95% CI 0.73-0.95, P = .07), and 13% increased likelihood for transplant (SHR 1.13, 95% CI: 1.07, 1.20, P < .001). Many patients bypassed the nearest transplant hospital, and longer patient travel distance was associated with favorable waitlist outcomes.