The presence of Philadelphia chromosome does not confer poor prognosis in adult pre-B acute lymphoblastic leukaemia in the tyrosine kinase inhibitor era - a surveillance, epidemiology, and end results database analysis

The BCR-ABL1 fusion gene is caused by a translocation between chromosomes 9 and 22, resulting in an abnormal chromosome 22 (Philadelphia chromosome; Ph). Prior to the introduction of tyrosine kinase inhibitors (TKI), the presence of BCR-ABL1 conferred a poor prognosis in patients with acute lymphoblastic leukaemia (ALL). We compared the survival of Ph+ and Ph-ALL during the period when TKIs were universally available in the US for Ph+ALL, using a Surveillance, Epidemiology, and End Results (SEER) Database analysis. A total of 2694 patients with pre-B ALL (206 Ph+ALL; 2488 Ph-ALL) aged 18 years, who were diagnosed between 2010 and 2014, were identified in SEER registries. The median overall survival (OS) was 32months in Ph+ALL (95% confidence interval [CI] 18 months-not reached) and 27 months (95% CI 24-30 months) in Ph-ALL (Log-rank test P-value 0.34). Older age was associated with worse prognosis in both Ph+ALL and Ph-ALL. Age-adjusted OS was inferior in Hispanics and African-Americans compared to non-Hispanic whites. Survival of pre-B ALL shows continued improvement with time. Philadelphia chromosome status does not confer poor prognosis in pre-B ALL in the TKI era: prognostic factors in pre-B ALL should be re-evaluated in the light of this finding.