Impact of complete molecular response on survival in patients with Philadelphia chromosome-positive acute lymphoblastic leukemia

The impact of achieving complete molecular response (CMR) in Philadelphia chromosome-positive (Ph⁺) acute lymphoblastic leukemia (ALL) remains undefined. We evaluated the impact of CMR on outcomes among 85 patients with Ph⁺ ALL who received first-line hyperfractionated cyclophosphamide, vincristine, doxorubicin, and dexamethasone alternating with methotrexate and high-dose cytarabine plus a tyrosine kinase inhibitor, had minimal residual disease (MRD) assessments for BCR-ABL1 by quantitative polymerase chain reaction at complete remission (CR) and at 3-month time points, and did not undergo allogeneic stem cell transplantation (SCT). MRD status at 3 months had better discrimination for overall survival (OS; P = .005) and relapse-free survival (RFS; P = .002) than did MRD status at CR (P = .11 and P = .04, respectively). At 3 months, achievement of CMR vs response less than CMR was associated with longer median OS (127 vs 38 months, respectively; P = .009) and RFS (126 vs 18 months, respectively; P = .007). By multivariate analysis, only CMR at 3 months was prognostic for OS (hazard ratio, 0.42; 95% confidence interval, 0.21-0.82; P = .01). Patients with Ph⁺ ALL who achieve CMR at 3 months have superior survival compared with those with lesser molecular responses and have excellent long-term outcomes even without SCT.