Radiolabeled Anti-CD45 Antibody with Reduced-Intensity Conditioning and Allogeneic Transplantation for Younger Patients with Advanced Acute Myeloid Leukemia or Myelodysplastic Syndrome.

Biology of blood and marrow transplantation : journal of the American Society for Blood and Marrow Transplantation

PubMedID: 24858425

Mawad R, Gooley TA, Rajendran JG, Fisher DR, Gopal AK, Shields AT, Sandmaier BM, Sorror ML, Deeg HJ, Storb R, Green DJ, Maloney DG, Appelbaum FR, Press OW, Pagel JM. Radiolabeled Anti-CD45 Antibody with Reduced-Intensity Conditioning and Allogeneic Transplantation for Younger Patients with Advanced Acute Myeloid Leukemia or Myelodysplastic Syndrome. Biol Blood Marrow Transplant. 2014;.
We treated patients under age 50 years with (131)I-anti-CD45 antibody combined with fludarabine and 2 Gy total body irradiation to create an improved hematopoietic cell transplantation (HCT) strategy for advanced acute myeloid leukemia or high-risk myelodysplastic syndrome patients. Fifteen patients received 332-1,561 mCi of (131)I, delivering an average of 27 Gy to bone marrow, 84 Gy to spleen, and 21 Gy to liver. Although a maximum dose of 28 Gy was delivered to the liver, no dose-limiting toxicity was observed. Marrow doses were arbitrarily capped at 43 Gy to avoid radiation-induced stromal damage; however no graft failure or evidence of stromal damage was observed. Twelve patients (80%) developed Grade II graft-versus-host disease (GVHD), one patient developed Grade III GVHD, and no patients developed Grade IV GVHD during the first 100 days after HCT. Of the 12 patients with chronic GVHD data, 10 developed chronic GVHD, generally involving the skin and mouth. Six patients (40%) are surviving after a median of 5.0 years (range, 4.2 to 8.3 years). The estimated survival at 1 year was 73% among the 15 treated patients. Eight patients relapsed, 7 of whom subsequently died. The median time to relapse among these 8 patients was 54 days (range, 26 to 1364 days). No cases of non-relapse mortality were observed in the first year after transplant. However, two patients died in remission from complications of chronic GVHD and cardiomyopathy, at 18 months and 14 months after transplant, respectively. This study suggests that patients may tolerate myeloablative doses >28 Gy delivered to the liver using (131)I-anti-CD45 antibody in addition to standard reduced intensity conditioning. Moreover, the arbitrary limit of 43 Gy to the marrow may be unnecessarily conservative, and continued escalation of targeted radioimmunotherapy doses may be feasible to further reduce relapse.