Second Haploidentical PBSC Transplantation From the Same Donor After Early Relapse without Gvhd in Patients with Acute Leukemia

Early relapse (within 120 days) of high risk acute leukemia after any form of allogeneic HCT, augers a poor outcome. We report our experience with 4 such patients who relapsed within 120 days of undergoing a haploidentical PBSCT with or without posttransplant cyclophosphamide. None developed GVHD even with prophylactic DLI. Three had relapsed refractory AML at the time of the first haploidentical HCT and one was transplanted for high risk ALL. The marrow blast count at the time of second transplant was 20-80%. The patients were conditioned with Fludarabine or Cladribine with melphalan (70 mg/m2) or oral busulfan (4mg/kg) and did not receive any GVHD prophylaxis. Cryopreserved PBSC graft was infused with CD34+ cells varying between 2-3 x 10 ^6/ kg. All the patients engrafted within 14 days and all developed grade 2-3 acute GVHD by day 10. GVHD was treated with steroids and etanercept along with tacrolimus and MMF. One patient succumbed early to multidrug resistant Klebsiella sepsis on day 15. The BM on day 30 in the other 3 patients showed 100 % donor chimerism with MRD levels of less than 0.1% on flow cytometry. At a short follow up of 90 days from the second haploidentical HCT, two out of three patients are alive in CR with tapering immunosuppresion and the other was lost to follow up after 50 days. Our data shows that a haploidentical graft can induce a potent enough GVL effect to induce remission even in refractory leukemia. These findings highlight the fact that even if a patient with refractory leukemia relapses early after an allogeneic HCT without developing GVHD, they deserve a second graft from the same donor with minimally toxic conditioning with the purpose of inducing a GVHD/GVL effect.