Background PNH is an acquired clonal disorder of the hemopoietic stem cells for which the only curative treatment is allogeneic hematopietic stem cell transplantation (allo-HSCT). But allo-HSCT is challenging for those who have no HLA-matched donors.Several recent studies have shown that haploidentical HSCT for patients with hematological malignancy can achieved comparable outcomes with HLA-identical sibling transplantation . There are very few reports on the use of haploidentical HSCT for PNH . Is haploidentical HSCT a valid alternative option for patients with PNH?

Methods 19 PNH patients received allo-HSCT between Dec 2007 and Oct 2015 at our institution. 12 donors were HLA-haploidentical and 7 were HLA-matched siblings. The patients were aged 8 to 54 years (median 28 years) . Of the 12 haploidentical donors, 6 were siblings, 2 fathers,2 mothers,1 son and 1 daughter. 12 patients with haploidentical donors received a myeloablative conditioning regimen consisting of busulfan, cyclophosphamide and ATG (anti-thymocyte globulin), 7 patients with identical siblings were given a reduced intensity conditioning. G-CSF-mobilized bone marrow and peripheral blood stem cells were transplanted as graft. Prophylaxis for graft-versus-host disease (GVHD) consisting of cyclosporine or tacrolimus + short-term methotrexate + mycophenolate mofetil was used for 12 patients with haploidentical donors, and cyclosporine + short-term methotrexate for 7 with identical siblings.

Results All 19 patients were engrafted successfully. The median time of neutrophils (ANC) reached to 0.5×109/L and platelets (PLT) reached to 20×109/L was 12 days and 15 days in haploidentical group , and that to identical group was 11 days and 13 days ,respectively. There were 2 patients developed grade Ⅱ acute GVHD in haploidentical group while 1 patients with grade Ⅳ aGVHD in identical group . Limited chronic GVHD was observed in 2/12 patients in haploidentical group and 1/7 patients in identical group. After a median follow-up time of 22.0 (range 4.0-42.0) months, the 3-year OS probability was 77.8±13.9% and 85.7±13.2% for haploidentical and identical group,respectively (P=0.03). 2 patients died of treatment-related mortality in haploidentical group, including severe pulmonary infection (n=1) and transplant-associated thrombotic microangiopathy (n=1) ,and 1 died of severe aGVHD in identical group. No patients were documented to have a recurrence of a PNH clone after HSCT in both groups.

Conclusion This report seemed that long-term outcomes of HLA- haploidentical HSCT in patients with PNH were comparable to that of HLA- matched donor at our institution . Haploidentical HSCT should be considered as a valid alternative option for PNH patients without HLA- matched donors .

Disclosures

No relevant conflicts of interest to declare.

Author notes

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Asterisk with author names denotes non-ASH members.

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