Impact of Additional Cytogenetic Abnormalities in Adults with Philadelphia Chromosome–Positive Acute Lymphoblastic Leukemia Undergoing Allogeneic Hematopoietic Cell Transplantation

• Additional cytogenetic abnormalities (ACA) are common in Ph+ ALL.
• Monosomy 7 was the most common ACA in our cohort.
• When TKI therapy and allogeneic HCT were utilized as part of adult Ph+ ALL therapy, the presence of ACA appeared to have a significant deleterious effect on outcomes.

The occurrence of additional cytogenetic abnormalities (ACAs) is common in Philadelphia chromosome–positive acute lymphoblastic leukemia (Ph+ ALL) but is of unknown significance in the tyrosine kinase inhibitor (TKI) era. We retrospectively analyzed data from a consecutive case series of adults with Ph+ ALL who had undergone allogeneic hematopoietic cell transplantation (alloHCT) at City of Hope between 2003 and 2014. Among 130 adults with Ph+ ALL who had TKI therapy before alloHCT, 78 patients had available data on conventional cytogenetics at diagnosis and were eligible for outcomes analysis. ACAs were observed in 41 patients (53%). There were no statistically significant differences in median age, median initial WBC count, post-HCT TKI maintenance, or disease status at the time of transplant between the Ph-only and ACA cohorts; however, the Ph-only cohort had a higher rate of minimal residual disease positivity at the time of HCT. Three-year leukemia-free survival (79.8% versus 39.5%, P = .01) and 3-year overall survival (83% versus 45.6%, P = .02) were superior in the Ph-only cohort compared with the ACA cohort, respectively. Monosomy 7 was the most common additional aberration observed in our ACA cohort (n = 12). Thus, when TKI therapy and alloHCT are used as part of adult Ph+ ALL therapy, the presence of ACAs appears to have a significant deleterious effect on outcomes post-HCT.