Monotherapy Immunosuppression in Pediatric Heart Transplant Recipients

Although dual-drug immunosuppression is standard for rejection prophylaxis in pediatric heart transplant (HT), single-drug immunosuppression (monotherapy) may be appropriate for certain patients. We describe the experience with monotherapy in select patients at a single institution.

Retrospective review of HT patients at a pediatric transplant center who underwent HT between 1/2001-12/2020 and were treated with calcineurin-inhibitor monotherapy for > 1 month. Patients were transitioned to monotherapy due to concerns for over-immune suppression, including recurrent infection, neutropenia, or post-transplant lymphoproliferative disorder (PTLD). Clinical characteristics and patient outcomes were analyzed.

During the study period, 16/318 (5%) HT patients were placed on monotherapy at a median of 4.6 years post-HT (IQR 1.8-6.9 years). Most patients on monotherapy were transplanted as infants (81%, 13/16), 56% (9/16) were male, and 50% (8/16) underwent HT for congenital heart disease (CHD). Most (81%) were on tacrolimus monotherapy. The indication for monotherapy was recurrent infection in 50%, PTLD in 31%, and neutropenia in 19%. At a median follow-up of 1.5 years (IQR 1.1-2.2 years), there were no episodes of moderate or greater rejection and no evidence of coronary allograft vasculopathy. At last follow-up, 87% of patients remain on monotherapy, and 94% of patients are alive and well, including one patient who has continued monotherapy for over 15 years.

Monotherapy immunosuppression with calcineurin inhibitors may be preferred in a subset of pediatric HT patients with evidence of over-immune suppression without conferring increased risk of rejection.