Accelerated and blastic phase of chronic myeloid leukemia

Opinion statement

There is currently no standard treatment for the blastic phase of chronic myeloid leukemia (CML-BC), which is a chemoresistant form of acute leukemia. Current approaches include using standard acute myeloid leukemia (AML) regimens in an effort to induce remission, variations of these approaches with drugs that seem more active in this specific leukemia, and the direct entry of patients into studies of investigational agents. Although the likelihood of achieving remission is small, immediate bone marrow transplantation in remission should be considered because it provides the only opportunity for long-term survival at this time. Allogeneic transplantation is preferred, but autologous transplantation of an early chronic phase marrow may provide benefit. Often, however, the duration of chemotherapy-induced remission of blast crisis is very short and may preclude entry into a transplant program. In addition, the patient may not be a candidate due to donor issues, age, or medical problems. If transplant is not an option, maintenance interferon is often used, although its benefit is uncertain.

For patients in the accelerated phase of the disease, which is characterized by a variety of clinical presentations and cytogenetic abnormalities, the possibility of favorably manipulating the disease is greater. Again, there is no standard treatment, and clinical trials are recommended as first-line therapy. Treatment in the accelerated phase includes standard AML chemotherapy regimens, combinations of new agents, and the combination of cytostatic agents with interferon. Patients whose accelerated phase reverts to chronic phase after treatment may become candidates for bone marrow transplantation. However, current new approaches to the chronic phase applied in accelerated phase as well as new approaches directed specifically toward accelerated phase may lead to prolonged stabilization without bone marrow transplantation. In view of a median age of 55 at diagnosis of chronic phase, nontransplant regimens for accelerated phase that produce long-term benefit are urgently needed.