Pre-Transplant Consolidation Chemotherapy for Acute Lymphocytic Leukemia (ALL) Does Not Impact Outcomes after Allogeneic Hematopoietic Cell Transplantation (alloHCT)

Most adult ALL protocols include consolidation chemotherapy, yet whether the consolidation is beneficial in patients undergoing alloHCT in first complete remission (CR1) remains uncertain. We therefore studied the impact of consolidation chemotherapy on transplant outcomes of 75 consecutive ALL patients who received alloHCT in CR1 between 2004 and 2013. Patients who received at least 1 cycle of consolidation (n= 51: 1 cycle, n=25; ≥2 cycles, n=26) were compared to those without consolidation (n=24) chemotherapy prior to alloHCT. The median age of entire cohort was 42 years (range, 19-67) and 59% were males. Half had Ph+ ALL and 16% had CNS leukemia. Patients received median of 2 cycles of induction chemotherapy (range, 1-5), and the median time from diagnosis to CR1 was 1.6 months (range, 1.1-2.9). Among 54 patients evaluable for minimal residual disease (MRD), 42 were MRD negative prior to alloHCT. Most patients received myeloablative conditioning (67%) and umbilical cord blood (UCB, 63%) alloHCT. Patients in ≥1 consolidation group were more often transplanted after 2008 (75% vs. 31%, p<0.01) as compared to no consolidation group, however other patient, disease and transplant characteristics were similar in both groups. At a median follow up of 4 years (range, 1-8), patients treated with ≥1 cycles of consolidation versus no consolidation had similar 1-year non-relapse mortality (24% vs. 29%, p=0.23), 2-year leukemia relapse (23% vs. 25%, p=0.44), leukemia-free survival (48% vs. 36%, p=0.18) and overall survival (61% vs. 45%, p=0.15), respectively. Cumulative incidence of relapse was lower in MRD negative patients (17% vs 50% MRD+, p=0.03) and UCB recipients (15% vs 37% related donor, p=0.02). Our data suggest that ALL patients with available donor undergoing alloHCT in CR1 may not benefit from further pre-transplant consolidation chemotherapy.