Long-term remission in a patient with BCR/ABL-positive acute myeloid leukaemia on maintenance therapy with imatinib

Prolonged survival with imatinib mesylate combined with chemotherapy and allogeneic stem cell transplantation in de novo Ph+ acute myeloid leukemia

BACKGROUND

De novo Philadelphia chromosome-positive (Ph+) acute myeloid leukemia (AML) is a rare disease with a poor prognosis. Imatinib mesylate (IM) is the standard treatment for Ph+ chronic myeloid leukemia and Ph+ acute lymphoblastic leukemia; however, its role in Ph+ AML has not been extensively investigated.

METHODS

Two patients aged of 46 and 19 years were diagnosed with de novo Ph+ AML according to the WHO Classification of Myeloid Neoplasms (2002) and the French-American-British (FAB) classification systems (1989). Cytogenetic analysis confirmed the presence of t(9;22). Standard RT-PCR was used to detect expression of the BCR-ABL1 fusion gene. Minimal residual disease was monitored by RQ-PCR for the BCR-ABL1/ABL ratio. Both patients received initial IM therapy combined with daunorubicin-based chemotherapy followed by allogeneic hematopoietic stem cell transplantation (allo-HSCT) and IM maintenance treatment after allo-HSCT.

RESULTS

Both patients achieved long-term disease-free survival with complete hematologic response, complete molecular response, and complete cytogenetic response for 44 and 48 months, respectively.

CONCLUSIONS

Our cases indicate that IM combined with daunorubicin-based chemotherapy followed by allo-HSCT and IM maintenance treatment is associated with a favorable outcome for de novo Ph+ AML, especially when IM is used in an early phase of AML.

The potential for dasatinib in treating chronic lymphocytic leukemia, acute myeloid leukemia, and myeloproliferative neoplasms

Dasatinib is a kinase inhibitor that inhibits BCR-ABL, Src family kinases, c-Kit, and platelet-derived growth factor receptor kinase. It is licensed for the first- and second-line treatment of chronic myeloid leukemia and second-line treatment of Philadelphia chromosome-positive acute lymphoblastic leukemia on the basis of BCR-ABL inhibition, but the activity of dasatinib against additional molecular targets may enable treatment of other hematologic disorders. Potential targets for dasatinib in chronic lymphocytic leukemia (CLL) include Lyn (a Src family kinase), ABL, and the associated CD40 pathway. Although dasatinib monotherapy has modest clinical activity in CLL, ongoing studies are evaluating combination treatment. In acute myeloid leukemia (AML), FLT3, Lyn, c-Kit, and BCR-ABL are expressed in a subpopulation of patients. To date, clinical responses to dasatinib in patients with unselected AML have been mixed and larger studies are needed, particularly correlating clinical response to molecular markers. Imatinib has been used successfully to treat patients with chronic eosinophilic disorders with the FIP1L1-PDGFRA fusion kinase; limited clinical data indicate that dasatinib could be active in imatinib-resistant disease. Ongoing clinical studies should further define the value of dasatinib in these disorders.