The prognostic value of minimal residual disease (MRD) assessed by multi-parameter flow cytometry (MFC) was investigated among 340 adult patients with B-cell acute lymphoblastic leukaemia (B-ALL) treated between 2004 and 2014 using regimens including the hyperCVAD (hyperfractionated cyclophosphamide, vincristine, doxorubicin, dexamethasone, methotrexate, cytarabine) backbone. Among them, 323 (95%) achieved complete remission (CR) and were included in this study. Median age was 52 years (range, 15-84). Median white blood cell count (WBC) was 9·35 × 10(9) /l (range, 0·4-658·1 ×1 0(9) /l). MRD by MFC was initially assessed with a sensitivity of 0·01%, using a 15-marker, 4-colour panel and subsequently a 6-colour panel on bone marrow specimens obtained at CR achievement and at approximately 3 month intervals thereafter. MRD negative status at CR was associated with improved disease-free survival (DFS) and overall survival (OS) (P = 0·004 and P = 0·03, respectively). Similarly, achieving MRD negative status at approximately 3 and 6 months was associated with improved DFS (P = 0·004 and P < 0·0001, respectively) and OS (P = 0·004 and P < 0·0001, respectively). Multivariate analysis including age, WBC at presentation, cytogenetics (standard versus high risk) and MRD status at CR, 3 and 6 months, indicated that MRD negative status at CR was an independent predictor of DFS (P < 0·05). Achievement of an MRD negative state assessed by MFC is an important predictor of DFS and OS in adult patients with ALL.

Background

The long-term efficacy of a combination of chemotherapy and dasatinib in patients with Philadelphia chromosome-positive (Ph+) acute lymphoblastic leukemia (ALL) is not well established.

Methods

Patients received dasatinib with 8 cycles of alternating hyperfractionated cyclophosphamide, vincristine, doxorubicin, and dexamethasone and high-dose cytarabine and methotrexate. Patients in complete remission (CR) continued maintenance dasatinib, vincristine, and prednisone for 2 years, which was followed by dasatinib indefinitely. Patients eligible for allogeneic stem cell transplantation (SCT) received it during their first CR.

Results

Seventy-two patients with a median age of 55 years (range, 21-80 years) were treated; 69 (96%) achieved CR. Among them, 57 (83%) achieved cytogenetic CR after 1 cycle, and 64 (93%) achieved a major molecular response at a median of 4 weeks (range, 2-38 weeks). Sixty-five patients (94%) were negative for minimal residual disease assessed by flow cytometry at a median of 3 weeks (range, 2-37 weeks). Dasatinib-related grade 3 and 4 adverse events included bleeding, pleural/pericardial effusions, and elevated transaminases. With a median follow-up of 67 months (range, 33-97 months), 33 patients (46%) were alive, and 30 (43%) were in CR; 12 underwent allogeneic SCT. Thirty-nine patients died (3 at induction, 19 after relapse, 7 after SCT performed during first CR, and 10 during CR). The median disease-free survival and overall survival were 31 (range, 0.3-97 months) and 47 months (range, 0.2-97 months), respectively. Seven relapsed patients had BCR-ABL kinase domain mutations, including 4 with T315I.

Conclusions

A combination of chemotherapy with dasatinib is effective in achieving long-term remission for patients with newly diagnosed Ph + ALL.