Cyclophosphamide conditioning in patients with severe aplastic anaemia given unrelated marrow transplantation: A phase 1-2 dose de-escalation study

Paolo Anderlini, Juan Wu, Iris Gersten, Marian Ewell, Jakob Tolar, Joseph H. Antin, Roberta Adams, Sally Arai, Gretchen Eames, Mitchell E. Horwitz, John McCarty, Ryotaro Nakamura, Michael A. Pulsipher, Scott Rowley, Eric Leifer, Shelly L. Carter, Nancy L. DiFronzo, Mary M. Horowitz, Dennis Confer, H. Joachim DeegMary Eapen

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Abstract

BACKGROUND: The optimum preparative regimen for unrelated donor marrow transplantation in patients with severe aplastic anaemia remains to be established. We investigated whether the combination of fludarabine, anti-thymocyte globulin, and total body irradiation (TBI) would enable reduction of the cyclophosphamide dose to less than 200 mg/kg while maintaining engraftment and having a survival similar to or better than that with standard regimens using a cyclophosphamide dose of 200 mg/kg (known to be associated with significant organ toxicity) for unrelated donor transplantation for severe aplastic anaemia. We have previously shown that cyclophosphamide at 150 mg/kg resulted in excess toxicity and its omission (0 mg/kg) resulted in unacceptable graft failure (three of three patients had secondary graft failure). Here we report results for the 50 mg/kg and 100 mg/kg cohorts. METHODS: In a multicentre phase 1-2 study, patients (aged ≤65 years) with severe aplastic anaemia, adequate organ function, and an unrelated adult marrow donor HLA matched at the allele level for HLA A, B, C, and DRB1 or mismatched at a single HLA locus received bone marrow grafts from unrelated donors. All patients received anti-thymocyte globulin (rabbit derived 3 mg/kg per day, intravenously, on days -4 to -2, or equine derived 30 mg/kg per day, intravenously, on days -4 to -2), fludarabine (30 mg/m2 per day, intravenously, on days -5 to -2), and TBI (2 Gy). Cyclophosphamide dosing started at 150 mg/kg and was de-escalated in steps of 50 mg/kg (to 100 mg/kg, 50 mg/kg, and 0 mg/kg). The primary endpoint was the selection of the optimum cyclophosphamide dose based on assessments of graft failure (primary or secondary), toxicity, and early death during 100 days of follow-up after the transplant; this is the planned final analysis for the primary endpoint. This trial is registered with ClinicalTrials.gov, number NCT00326417. FINDINGS: 96 patients had bone marrow transplant. At day 100, 35 (92%) of 38 patients were engrafted and alive in the cyclophosphamide 50 mg/kg cohort and 35 (85%) of 41 in the 100 mg/kg cohort. Cyclophosphamide 50 mg/kg and 100 mg/kg resulted in posterior means for fatality without graft failure of 0·7% (credible interval 0-3·3) and 1·4% (0-4·9), respectively. Three patients (8%) had graft failure with cyclophosphamide 50 mg/kg and six (15%) with cyclophosphamide 100 mg/kg. Four (11%) patients had major regimen-related toxicity with cyclophosphamide 50 mg/kg and nine (22%) with cyclophosphamide 100 mg/kg. The most common organ toxicity was pulmonary (grade 3 or 4 dyspnoea or hypoxia including mechanical ventilation), and occurred in three (8%) and four (10%) patients given cyclophosphamide 50 mg/kg and 100 mg/kg, respectively. INTERPRETATION: Cyclophosphamide at 50 mg/kg and 100 mg/kg with TBI 2 Gy, fludarabine, and anti-thymocyte globulin results in effective conditioning and few early deaths after unrelated donor transplantation for severe aplastic anaemia. These doses of cyclophosphamide provide a framework for further regimen optimisation strategies. FUNDING: US National Heart, Lung, and Blood Institute and National Cancer Institute.

Original languageEnglish (US)
Pages (from-to)e367-e375
JournalThe Lancet Haematology
Volume2
Issue number9
DOIs
StatePublished - 2015
Externally publishedYes

ASJC Scopus subject areas

  • Hematology

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    Anderlini, P., Wu, J., Gersten, I., Ewell, M., Tolar, J., Antin, J. H., Adams, R., Arai, S., Eames, G., Horwitz, M. E., McCarty, J., Nakamura, R., Pulsipher, M. A., Rowley, S., Leifer, E., Carter, S. L., DiFronzo, N. L., Horowitz, M. M., Confer, D., ... Eapen, M. (2015). Cyclophosphamide conditioning in patients with severe aplastic anaemia given unrelated marrow transplantation: A phase 1-2 dose de-escalation study. The Lancet Haematology, 2(9), e367-e375. https://doi.org/10.1016/S2352-3026(15)00147-7