Chronic myeloid leukemia: the drug that changed everything
In recent history, chronic myeloid leukemia was treated in a manner similar to other cancers with intensive chemotherapy. As is the case with everything, we are afraid of what we don’t know, and our lack of knowledge regarding chronic myeloid leukemia made treatment options unclear. However, identifying the main genetic abnormality, “the Philadelphia chromosome” and the use of tyrosine kinase inhibitors, the first-generation drug imatinib, led to significant improvement in the outcome of such patients with over 94% of patients responding in the chronic stage. The term “chronic stage” signifies that this is the only stage easily treatable in CML.
The disease goes through three stages which are the chronic, the accelerated and the blast crisis. The blast crisis is the worst, most fatal and most resistant to treatment. Other agents are used for the blast crisis, but results are nowhere as positive as those achieved if the patient is “caught” during the chronic phase. The other main challenge facing the treatment of CML is the presence of resistance against this “magic drug”. Resistance can occur when the cancer modulates his defenses against the drug through changing its genetics, which the main target of this drug. However, several second-generation drugs were developed for this purpose. Stem cell transplantation remains a viable option with good results. It is safe to say that CML is the best managed type of leukemia to this day in its chronic stage.