Phase-2 trial of an intensified conditioning regimen for allogeneic hematopoietic cell transplant for poor-risk leukemia.

Patients with poor-risk leukemia have a high relapse rate despite allogeneic transplant. We report on the phase-2 trial of an intensified allogeneic transplant regimen whose aim was tolerable toxicity and durable remission. Study patients (n=30) had unfavorable first remission cytogenetics, progression from myelodysplasia or active disease due to induction failure or relapse. Conditioning was i.v. BU, targeted to a first-dose plasma area under the curve (AUC) of 700-900 μM min, VP-16 at 30 mg/kg of adjusted ideal body weight and fractionated TBI (FTBI) at 1200 cGy in 10 fractions. GVHD prophylaxis was CsA and mycophenolate mofetil. Regimen-related toxicities (Bearman) included grade II mucositis in 29 patients (97%) and grade III in one patient, grade II-III sinusoidal obstructive syndrome in 2 patients (7%), and grade 2-3 (CTC) skin toxicity in 8 patients (27%). The 30- and 100-day TRMs were 0 and 7% respectively. The median follow-up was 83.7 months (60.7-96.4) for surviving patients. The 5-year overall and disease-free survival was 40% for all patients. Cumulative 5-year relapse incidence (RI) was 23% and TRM was 37%. We have shown promising OS and RI in these poor-risk patients, who typically have few curative options.