Integrated prognostic value of MRD and cytogenetics in adolescent and adult B-cell acute lymphoblastic leukaemia.

B-cell acute lymphoblastic leukaemia (B-ALL) in adolescents and adults remains challenging due to high relapse rates and suboptimal outcomes. Although minimal residual disease (MRD) and cytogenetic risk classification are independent prognostic indicators for B-ALL in adolescents and adults, their combined utility remains under explored. This retrospective study analysed 609 adolescent and adult patients with B-ALL to evaluate the integrated prognostic value of MRD at end of induction (MRD1) and after first consolidation (MRD2), combined with cytogenetic risk stratification (standard risk [SR] vs. poor risk [PR]). Although cytogenetic risk alone was not an independent prognostic factor, MRD positivity at either time point significantly predicted inferior 5-year RFS and OS in PR patients. Allogeneic haematopoietic stem cell transplantation (allo-HSCT) improved outcomes overall; however, PR patients with MRD2 positivity remained at high risk of relapse post-transplant. Multivariate analysis identified MRD1 and MRD2 as independent predictors of both relapse (RFS HR = 2.048) and mortality (OS HR = 1.979) in PR patients (all p < 0.01). These results demonstrate that combining MRD assessment with cytogenetic risk improves risk stratification, precisely identifying poor-risk patients with persistent MRD who may benefit from treatment intensification, including novel strategies post-transplant.