PARIS, France--Cyclophosphamide with total body irradiation (TBI) provides better survival rates than cyclophosphamide(Drug information on cyclophosphamide) plus busulfan(Drug information on busulfan) when used as a pre-autologous bone marrow transplant (ABMT) conditioning regimen in patients with advanced acute myeloid leukemia (AML), a University of Minnesota study has found.
The Minnesota study included 75 patients, 35 of whom were participants in a randomized trial comparing the two conditioning regimens. Autologous marrow was purged with 4-hydroperoxycyclo-phosphamide before reinfusion.
For patients beyond first remission, cyclophosphamide (Cytoxan, Neosar), 120 mg/kg, plus 1,320 cGy TBI given in eight fractions over 4 days, was associated with a 2-year disease-free survival rate of 38%, compared with 7% for a regimen of cyclophosphamide, 200 mg/kg, plus busulfan (Myleran), 16 mg/kg.
"There was a clear advantage of cyclophosphamide/TBI over busulfan/cyclophosphamide," Kathryn E. Dusenbery, MD, said at the American Radium Society meeting. Among patients in first remission, however, the survival differences did not reach statistical significance.
Dr. Dusenbery pointed out that there were no differences between the two regimens in the time required for the absolute neutrophil count to reach 500, or in the duration of hospital stay. Likewise, she observed, the incidence of acute toxicity, including interstitial pneumonitis and hemorrhagic cystitis, was similar in both study arms.
In contrast, veno-occlusive disease developed in seven patients conditioned with busulfan/cyclophosphamide, but in none of those who received chemotherapy plus TBI.
"In the future, our preferred regimen will be cyclophosphamide and TBI," Dr. Dusenbery said. "It is unlikely that we will be able to escalate the TBI doses too much beyond the 1,320 cGy we use now," she added.