Daratumumab in Heart Transplantation: A Pilot Study in a Pediatric and Young Adult Series

Background Anti‐HLA sensitization is associated with antibody‐mediated rejection and represents a major challenge to successful heart transplantation. Daratumumab, an IgGκ monoclonal antibody targeting the CD38 receptor on plasma cells, was initially developed for the treatment of multiple myeloma. In transplantation, it may help reduce antibody production by inducing plasma cell apoptosis. Its use in heart transplantation has been limited, particularly in pediatric patients, with only two cases reported in the literature. Methods Since 2020, four heart transplant recipients at CHU Sainte‐Justine developed donor‐specific antibodies (DSAs) and were treated with daratumumab intravenously (16 mg/kg once a week for a minimum of 6 weeks) for desensitization prior to heart transplantation or for the treatment of antibody‐mediated rejection. Their medical records were thoroughly analyzed (e.g., DSA levels, biopsy results) to assess the efficacy and safety of daratumumab treatment in four individual case studies. Results Three patients received daratumumab for antibody‐mediated rejection, and one received it as part of a desensitization protocol prior to heart transplantation. DSAs became undetectable in three of the patients. Despite this clearance, one died 18 months after treatment from coronary artery disease while awaiting a second transplant. In the fourth patient, a young adult with both cellular and antibody‐mediated rejection, treatment was ineffective despite two cycles. No major side effects were reported during or after daratumumab treatment. Conclusion In all treated patients, Daratumumab was well tolerated, with no major adverse effects except for secondary hypogammaglobulinemia. It may play a key role in managing acute antibody‐mediated rejection and desensitizing highly sensitized pediatric transplant recipients.