Hematopoietic Cell Transplantation for Chronic Lymphocytic Leukemia: Similar Efficacy of Non-Myeloablative and Myeloablative Conditioning; Long-Term Evaluation From the University of Minnesota.

Abstract 3385

Poster Board III-273

Allogeneic hematopoietic cell transplantation (HCT) for chronic lymphocytic leukemia (CLL) is increasingly utilized. We retrospectively analyzed outcomes of HCT for 43 patients with CLL at the University of Minnesota from February 1985 through March 2009 using myeloablative (MA, n=19) (total body irradiation [TBI] 1320 cGY in 8 fractions and cyclophosphamide [Cy] 60 mg/kg x 2 days) and non-myeloablative (NMA, n=24) preparative regimens (fludarabine 40 mg/m2 × 5 days or cladribine 50 mg/m2 IV with TBI 200cGy in 1 fraction and either oral busulfan [Bu] 8 mg/kg divided every 6 hours over 2 days or Cy 50 mg/kg x1 day). Graft-versus-host disease (GVHD) prophylaxis included cyclosporine (CSA) and methotrexate in most MA patients and CSA and mycophenolate mofetil (MMF) for all NMA patients. Median follow up for survivors was 3.3 years. Nine-two percent of NMA HCT took place after 2000 whereas only 26% of MA HCTs happened during this time. Most patients were male (15/19 MA, 20/24 NMA). Time from diagnosis to treatment was nearly twice as long in NMA vs. MA patients (median 72 vs. 39 months) with MA patients progressing through a median of 3 regimens (range, 1-5) and NMA 4 (1-7). Poor-risk cytogenetics (11q-, 17p-) were found in 5 MA and 10 NMA patients. Seven and 13 patients were fludarabine refractory in the MA and NMA groups, respectively. Eighteen patients in the MA group had matched related donors (MRD), while only 10 MRD were amongst the NMA patients. Umbilical cord blood stem cells were used in 12 NMA patients. Neutrophil recovery was slightly faster after NMA HCT vs. MA (median 12.5 vs. 18.5 days; p=0.14). Incidence of acute GVHD, grades II-IV, was similar (p=0.11) but grades III-IV at day 100 was more frequent in the NMA than the MA group (33% vs. 5%, p=0.04). The chronic GVHD incidence was 43% (95% CI, 18-68%) in MA and 29% in NMA (11-47%, p=0.08) patients. Transplant-related mortality (TRM) at 1 year was 42% (20-64) in the MA arm vs. 25% (8-42) (p=0.34) for the NMA group. Relapse rates at 3 years were higher in the NMA HCT group (MA 18% [0-36] vs. NMA 26% [8-44]). Three-year progression-free survival (PFS) was similar in MA (33% [13-55]) and NMA (39% [19-58]) patients (p=0.61). Overall survival at three years was also similar (MA 37%, [15-60] vs. NMA 52%, [30-70]) (p=0.28). While these data suggest that dose intensity may affect TRM and relapse, NMA HCT yields equivalent and encouraging PFS and OS as compared to MA HCT. Our results support further investigation of the role of allogeneic transplantation in the treatment of high risk and advanced CLL.