Chemotherapy and Imatinib in Young Adults With Acute Lymphoblastic Leukemia Ph (BCR-ABL) POSITIVE

20-25% of patients over 15 years with acute lymphoblastic leukemia (ALL) have the Philadelphia chromosome or BCR-ABL rearrangement. Traditionally, intensive chemotherapy followed by hematopoietic stem cell transplantation (HSCT) have formed the basis allogeneic treatment of this disease, but the results have been poor (60-75% complete remissions-RC-and probability of long-term survival less than 20%). The effectiveness of imatinib for hematologic responses in patients with Ph + (observed in phase I and II) led to its use in phase III trials in combination with chemotherapy. They saw a chance of obtaining the RC above 90%, with acceptable toxicity, a molecular response rate (MR) of 40-50%, and prolonged follow-up studies, a probability of disease-free survival (DFS ) of 30-50%, significantly higher than historical controls with the same chemotherapy without imatinib. This led to the approval of imatinib by the rating agencies in the U.S., Europe and Japan as a treatment for Ph + in combination with chemotherapy.

Of the studies that led to the approval of this indication for imatinib, and other incurred after, the following conclusions can be drawn:

There is no specific pattern of combination of imatinib (at doses of 600 mg / day, po) and chemotherapy. However, when compared with concomitant alternating with the first achieved a higher rate of RM at the end of induction, although this did not influence DFS.

In studies in elderly patients has achieved a high CR rate (almost 100% in all series), only imatinib and glucocorticoids, suggesting that an attenuated induction may be sufficient to achieve CR in young patients with minimal toxicity, which further compromises the administration of treatment and allow for an allogeneic HSCT with minimal toxic load possible.

Although there is no consensus on the indication of allogeneic HSCT in first CR when given imatinib associated with intensive chemotherapy is an option that is done in most studies.

The allogeneic HSCT is most effective when carried out in complete molecular response to or greater than when there is more residual disease. However, the impact of MRI to obtain early (after induction) on survival is not clear. So far-reaching goal is to make the TPH in complete molecular response situation or greater.

The relapse of the disease at the molecular level is still short-term (less than 3 months) of hematological relapse. This implies the need for frequent monitoring of residual disease (ER) The frequency of relapse post HSCT is high (around 30%), raising the need for any post HSCT treatment, including imatinib included. Are currently ongoing clinical trials comparing the systematic administration of imatinib after administration TPH face is detected only when ER.

The applicability of the administration of imatinib after HSCT is limited by toxicity related to the procedure of TPH, is making frequent dose reduction or discontinuation.

Therefore, a reasonable approximation treatment of Ph + outside the context of a clinical trial is to get as many molecular responses before allogeneic HSCT in a position to make the same MRI complete or greater. After TPH, must be very close monitoring of the ER, and imatinib is administered as soon as you notice the loss of molecular response.

In patients who can not make an allogeneic HSCT for lack of histocompatible donor or contraindications for its realization it is recommended imatinib and chemotherapy, although there are studies that have undergone an autologous HSCT, followed or not treatment "maintenance" with imatinib. The low toxicity of autologous HSCT and no effect of graft versus leukemia are strongly recommended the administration of maintenance therapy with imatinib combined with chemotherapy or not.