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.