Current status of stem cell transplantation in paroxysmal nocturnal hemoglobinuria

Paroxysmal nocturnal hemoglobinuria (PNH) is a clonal, acquired hematopoietic stem cell disorder, which is caused by activation of the complement system leading to life-threatening manifestations such as hemolysis, thrombosis, and marrow failure. Eculizumab is a complement inhibitor of C5, which acts by blocking complement-mediated hemolysis. It needs to be administered lifelong to the patient; hence, there are major financial implications. This drug is easily available in the Western countries; however, in low resource countries, where its availability is limited, hematopoietic stem cell transplantation (HSCT) still remains the main modality for achieving cure in PNH. PNH being a rare disease, large prospective studies and guidelines are scarce. To choose the ideal candidate for transplant is the real challenge. This article aims to review the trends in HSCT for PNH, such as the use of reduced-intensity conditioning to attain the graft versus PNH effect or the use of haploidentical donors. In the era of complement inhibitor therapy, the role of transplantation still needs to be explored.