Use of Bortezomib as Anti-Humoral Therapy in Kidney Transplantation

This study aimed to investigate the effect of bortezomib in the desensitization and treatment of acute antibody mediated rejection (AAMR) in kidney transplantation. Nine patients who received bortezomib therapy for desensitization (DSZ group, n = 3) or treatment of AAMR (AAMR group, n = 6) were included in this study. In the DSZ group, 2 patients required DSZ owing to positive cross match and 1 owing to ABO mismatch with high baseline anti-ABO antibody titer (1:1,024). Bortezomib was used at 1, 3, 8, and 11 days from the start of the treatment. In the AAMR group, 3 patients showed full recovery of allograft function after bortezomib use and decrease in donor specific anti-HLA antibody (HLA-DSA). However, 3 patients did not respond to bortezomib and experienced allograft failure. In the DSZ group, negative conversion of T-CDC (complement-dependent cytotoxicity) was achieved, and HLA-DSA was decreased to lower than a weak level (median fluorescence intensity [MFI] < 5,000) in 2 patients. In the case of ABO mismatch kidney transplantation, the anti-A/B antibody titer decreased to below the target (≤ 1:16) after bortezomib therapy. Therefore, bortezomib could be an alternative therapeutic option for desensitization and treatment of AAMR that is unresponsive to conventional therapies. Graphical Abstract Keywords: Kidney Transplantation, Bortezomib, Anti-Humoral Therapy, Desensitization, Antibody Mediated Rejection INTRODUCTION The presence of donor-specific anti-human leukocyte antigen antibodies (HLA-DSA) is a critical barrier to successful kidney transplantation (KT). Insufficient reduction or suppression of pre-formed HLA-DSA before KT can result in a hyper-acute or acute antibody mediated rejection (AAMR) (1). In addition, development of HLA-DSA after KT can induce not only acute but also chronic AMR, which could be associated with poor allograft survival (2). For these reasons, research has focused on protocol development to effectively suppress the humoral immune system in kidney transplant recipients (3). So far, the protocol of plasmapheresis, intravenous immune globulin (PP/IVIG), and rituximab (RTX) has been widely used for desensitization and the treatment of AAMR. This may be because the treatment only depletes B cells or removes circulating antibodies and does not suppress plasma cells that directly produce HLA-DSA (4). Recently, bortezomib, a proteasome inhibitor, was approved by the Food and Drug Administration for the treatment of multiple myeloma, and has been introduced for use in KT (5). Bortezomib inhibits antibody production from plasma cells, stimulates apoptosis of this cell type, and decreases the number of bone marrow-derived plasma cells (6). Therefore, it is expected that this drug would show stronger suppressive effect for humoral immunity compared with conventional therapies such as rituximab. However, clinical data on the use of bortezomib in KT is currently limited. Therefore, the aim of this study was to investigate the effect of bortezomib on desensitization before KT and the treatment of AAMR after KT.