Haploidentical transplantation as a promising therapy for relapsed hemophagocytic lymphohistiocytosis in an older adult patient.

Hemophagocytic lymphohistiocytosis (HLH) is a rare but severe and often overwhelming systemic hyper-inflammatory syndrome generally presenting with unexplained fevers, hepatosplenomegaly, and progressive multi-organ dysfunction. Treatment of HLH has two major goals: Halting the triggering event and controlling the overactive immune system. However, patients with primary or recurrent secondary HLH should subsequently undergo allogeneic HCT for long lasting disease remission. Hereby we present the case of a 69 years old man with recurrent HLH who underwent a reduced intensity conditioning of fludarabine, cyclophosphamide and low dose total body irradiation followed by a haploidentical marrow graft and post-transplantation cyclophosphamide (PTCy), tacrolimus and mycophenolate mofetil as GVHD prophylaxis. He achieved a durable remission of HLH symptoms despite persistent myeloid mixed chimerism. The use of haploidentical donors and PTCy as tolerance inducing regimen is feasible in HLH. The achievement of mixed donor chimerism may be enough to control the clinical manifestations and to cure HLH.