Abstract
PAX5 is one of the most frequently altered genes in B‑cell acute lymphoblastic leukemia (B‑ALL), yet the impact of its specific alterations on adult outcomes remains incompletely defined. We conducted a retrospective analysis of 42 adults with PAX5-mutated or rearranged B-ALL, including PAX5 P80R mutations (n = 6), PAX5 fusions (n = 11), and other PAX5 mutations (n = 25). The median age was 41 years and 83% were Hispanic. Complete remission and minimal residual disease negative rates after induction were 78.6% and 53.8%, respectively. Median overall survival (OS) was 30.1, 53.7, and not reached (NR) months for P80R, fusions, and other PAX5 mutations, respectively. Median relapse-free survival was 12.1, NR, and 88.5 months for the same groups. CDKN2A/B co-deletions trended toward inferior OS (HR 2.69, p = 0.105). In multivariate analysis, PAX5 fusions were independently associated with inferior OS (HR 7.79, p = 0.018). PAX5‑altered ALL represents a heterogeneous group with diverse mutations that may influence prognosis.