(P-TA-12) Therapeutic Plasma Exchange in Cardiac Transplantation Recipients with Antibody Mediated Rejection: A Comparison of Two Protocols

Therapeutic plasma exchange (TPE) is used to treat organ rejection by removing anti-HLA antibodies (Anti-HLA Ab) in transplant patients with antibody mediated rejection (AMR). Yet, insufficient objective outcome data limits improvement of TPE protocols for AMR in cardiac transplant (CT). We compare two protocols: (Con-TPE) conventional (5 procedures over 10 days), and (Int-TPE) intensive (8 procedures over 12 days) used when Con-TPE fails or there is a high level of Anti-HLA Ab. The aim is to assess efficacy of these approaches in cardiac transplant patients (CT-Pts).

Study

Design/Methods: A retrospective, IRB-approved study was conducted on all CT patients who received TPE for AMR at our institution from May 2009 to March 2023. Data collected included patient demographics, endomyocardial biopsy (MC bx) results, ECHO results after completion of TPE courses, and results of serial Anti-HLA antibodies (before, during, and after TPE courses). The study also examined concurrent anti-AMR treatments and 12-month survival rates. Patients with incomplete data or those receiving TPE outside of the protocol were excluded. Chi-square and Student's t-tests were used for the comparative analysis.


Results/Findings:

Sixty-four TPE courses were performed (48 CT-Pts with AMR) during the study period. Thirty-one were excluded, and 33 (24 CT-Pts) were analyzed. All patients were also receiving other therapies, including IVIG, steroids, and either ATG or bortezomib (Int-TPE CT-pts). Of the 33 courses, 25 (21 CT-pts) were Con-TPE, and 8 (6 CT-pts) were Int-TPE. Demographic data were similar across both groups (Table 1). In the Con-TPE group, 76.2% showed MC bx AMR improvement, compared to 50% in the Int-TPE group (Table 1). Improvement in left ventricular function was observed in 56.3% of the Con-TPE group versus 16.7% of the Int-TPE group. A higher occurrence of HLA class II than class I DSAs (75% vs. 25%, respectively) was noted, with class II DSAs showing a higher initial mean fluorescence intensity (MFI) (10012.8 vs. 3457.5). HLA-DQ was the most frequent among the HLA specificities and exhibited the highest mean MFI (12682.6). As shown in Table 1, Class I DSAs exhibited more significant MFI reductions at all three time points (P0-P1, P0-P2, and P0-PP) compared to class II. In the Con-TPE group, Class II DSAs increased at P0-P2 and P0-PP, indicating a rise in DSA levels post-TPE. The Int-TPE protocol led to greater MFI reductions for both HLA classes at all three time points (P0-P1, P0-P2, and P0-PP). Survival at 12 months was similar in both groups.

Conclusions: Both TPE protocols demonstrate evidence of effectiveness. The Int-TPE protocol leads to a greater MFI reduction in both Class I and II antibodies. However, similar rates of biopsy AMR or left ventricular function improvements are not seen. Further research is required to identify patients who would most benefit from upfront Int-TPE protocol.