Strategies for Moderate-risk Delisting in Highly Sensitized Patients.

Background/aim: Despite the donor-exchange program implementation for highly sensitized (HS) patients, no improvement in waiting list in those HS patients with 100% calculated panel reactive of antibodies (cPRA) is observed. Recently, it has been published the treatment with imlifidase in desensitization algorithm. However, there are low-risk strategies to reduce cPRA. A cPRA of <99.95% increase donor offer chances, so delisting (DL) strategies should be addressed in cPRA reduction. We propose an integral approach for DL from low to intermediate risk to assess the 100% HS patients on waiting list.

Methods: The common DL criteria for previously forbidden alleles were that they should neither have been present in previous transplants nor possess complement fixation ability. Low-risk phase of DL is based on historical mean fluorescence intensity (MFI) of <5000 in the last 2 years. The next phase risk is based on single-antigen test in 1/10 diluted serum with MFI value of <3000; without eplet mismatch (low-intermediate risk specificity), or with eplet mismatch from previous transplants (intermediate risk). The molecular mismatch may be assessed with the mismatch calculator tool from registry website (https://www.epregistry.com.br/).

Conclusions: Low-risk DL approaches are now widely used to reduce cPRA in HS patients; however, sometimes it is not enough to get transplanted and new tools are needed. Despite new treatments with imlifidase, some cases had anti-human leukocyte antigen rebound levels with a higher risk of rejection. Here, we propose a scaled DL approach would be a better therapeutic approach for HS patients whenever possible.