Philadelphia‐like B‐cell acute lymphoblastic leukaemia: Disease features and outcomes in the era of immunotherapy.

Summary: Philadelphia chromosome (Ph)‐like acute lymphoblastic leukaemia (ALL) is a high‐risk subtype with a gene expression profile similar to Ph‐positive ALL, due to activation of tyrosine kinase signalling. To understand the clinical implications of Ph‐like ALL, this single‐centre retrospective study evaluates outcomes in 268 adults, largely Hispanic ALL patients treated between 2013 and 2024, with a subgroup analysis of 139 haematopoietic stem cell transplantation (HSCT) patients. ALL subtypes included 68 (25.4%) Ph‐like, 89 (33.2%) Ph‐positive, and 111 (41.4%) Ph‐negative. Ph‐like patients were the youngest age at diagnosis (p = 0.007), most likely to have refractory disease (p < 0.001), and least likely to achieve minimal residual disease (MRD) negativity after induction (p = 0.031). Relative to Ph‐negative ALL, Ph‐like achieved worse event‐free survival (EFS) (HR = 1.66; 95% CI 1.12–2.46; p = 0.012), whereas Ph‐positive had improved EFS (HR = 0.60; 95% CI 0.38–0.93; p = 0.024) and cumulative incidence of relapse (CIR) (HR = 0.59; 95% CI 0.35–0.99; p = 0.046). Within the transplant subgroup, Ph status did not impact disease‐free survival (DFS), CIR, or overall survival (OS). However, patients who received blinatumomab within 1‐year pre‐HSCT had improved DFS (HR = 0.43; 95% CI 0.20–0.94; p = 0.034) and CIR (HR = 0.26; 95% CI 0.09–0.75; p = 0.13). In conclusion, our data suggest that Ph‐like is less likely to respond to standard induction therapy and HSCT may result in similar survival outcomes to Ph‐negative ALL. [ABSTRACT FROM AUTHOR]