Prospective evaluation of minimal residual disease monitoring to predict prognosis of adult patients with Ph‐negative acute lymphoblastic leukemia

Objective We investigated whether minimal residual disease (MRD) status in adult patients with Philadelphia chromosome (Ph)-negative acute lymphoblastic leukemia (ALL) is useful for decision on clinical indications for allogeneic hematopoietic stem cell transplantation (HSCT). Methods We prospectively monitored MRD after induction and consolidation therapy in adult patients with Ph-negative ALL. Results Among 103 adult ALL patients enrolled, 59 were Ph-negative, and MRD status was assessed in 51 patients. The probability of 3-year overall survival (OS) and disease-free survival (DFS) was 69% (95%CI 54-80) and 50% (95%CI 36-63), respectively. Patients who were MRD-negative after induction therapy (n = 15) had a significantly better 3-year DFS compared with those who were MRD-positive (n = 30; 73% vs 41%, P = 0.018). Patients who were MRD-positive after induction but became MRD-negative after consolidation chemotherapy C in the first course (n = 11) showed a significantly worse 3-year DFS compared with patients who were MRD-negative after induction chemotherapy A in the first course (45% vs 73%, P = 0.025). Conclusions These results indicate that DFS of about 70% can be expected in MRD-negative patients after induction therapy, and the patients did not benefit from HSCT in 1CR. This study was registered with the UMIN Clinical Trials Registry (UMIN-CTR), number UMIN000001519.