Successful management of sirolimus toxicity in a hematopoietic stem cell transplant patient using automated red blood cell exchange

Abstract

Background: Sirolimus is an immunosuppressive agent used in organ rejection prophylaxis in solid-organ transplantation, graft-vs-host disease prophylaxis in hematopoietic stem cell transplantation, and as an immune modulator for patients with lymphangioleiomyomatosis and vascular malformations. Sirolimus has a narrow therapeutic index with potential severe side effects, including hypertension, hepatotoxicity, nephrotoxicity, and neurotoxicity. Case Report: We report a case of a 19-year-old woman with severe sickle cell disease who underwent a matched unrelated hematopoietic stem cell transplantation, whose course was complicated by sirolimus toxicity. This case was challenging because sirolimus has no specific antidote, is largely bound to red blood cells (RBCs), has a high distribution volume, and cannot be removed by dialysis or plasmapheresis. Result: Due to the concern for toxicity, we looked into possibilities for rapid sirolimus clearance using automated RBC exchange. The treatment was effective in decreasing blood sirolimus levels within the therapeutic ranges. Conclusion: The use of RBC exchange is potentially safe and effective in the management of a case of sirolimus toxicity.