Feasibility of Interleukin-6 Receptor Blockade in Cardiac Antibody-mediated Rejection

Background. Antibody-mediated rejection (AMR) remains a significant cause of heart transplant mortality with few effective therapies. Methods. This study aimed to describe initial experience of using interleukin-6 receptor blockade with tocilizumab in the treatment of acute cardiac AMR at Barnes-Jewish Hospital/Washington University Transplant Center from July 2017 to May 2021 (n = 7). Clinical, echocardiographic, and serum alloantibody data were analyzed before and after treatment. Results. All participants demonstrated marked improvement in functional status. Echocardiographic data following 4-6 mo of tocilizumab revealed significant improvements in biventricular systolic function for all participants. Consistent reductions in donor-specific HLA or angiotensin type I receptor antibodies were not observed, suggesting that tocilizumab may act downstream of antibody production. No patient experienced drug-related complications that necessitated discontinuation of therapy. Conclusions. These findings provide initial insights into the safety and efficacy of interleukin-6 receptor blockade in the treatment of cardiac AMR and support the design of larger prospective studies.