Chronic myeloid leukemia (CML)
- Myeloproliferative neoplasm (blood cancer)
- New cases per year in Canada: 1-2 cases per 100 000 people per year (approx. 550 cases/year in Canada)
- Median age at diagnostic: 45-55 years old
- Splenomegaly (increased volume of the spleen)
- Constitutional symptoms such as fatigue, fever, night sweats, anorexia and weight loss, anemia and recurring infections
Physiopathology (blood and bone marrow):
- Increase leukocytes (granulocytosis)
- Myélogramme avec cellularité riche et déviation de la lignée granulocytaire
- Presence of the Philadelphia chromosome resulting a hybrid bcr/abl gene(Figure 1)
The initial CP of the disease, in which there may be no symptoms, presents in about 85% of patients with CML. Prior to recent treatment advances, the CP lasted 5-6 years, the AP 6-9 months, and the BC 3-6 months.
Three approaches to treatment are known to exert a positive influence on the natural history of the disease:
- Allogeneic hematopoietic stem-cell transplantation (AHSCT)
- Interferon alpha (IFN-α) alone or in combination with low-dose cytarabine
- Tyrosine kinase inhibitors (TKI)
To this day, it is the only treatment that offers the only prospect for the cure of CML. In general, the best results are obtained in CP with approximately 80% long-term remission. Despite its effectiveness, only about 25% of CML patients are eligible for the procedure, owing to age restrictions, absence of suitable donors, and the higher incidence of graft-versus-host disease.
Interferon alpha (IFN-α)
Therapy with interferon alpha is most effective in early-phase CP-CML. Although IFN-a has expanded the therapeutic options for patients who are ineligible for transplant, the treatment has its shortcomings. Treatment for one or more years is required to establish the presence and degree of cytogenetic response, due to the slow kinetics of the biological response. For more than 50% of patients, side-effects related to IFN-a are intolerable and require dose reduction, while up to 25% discontinue treatment due to severe adverse effects.