In the initial treatment of chronic myeloid leukemia (CML), Sprycel® (dasatinib) produces higher response rates than Gleevec® (imatinib). These results were presented at the 2010 annual meeting of the American Society of Clinical Oncology.
Each year in the United States, approximately 5000 people are diagnosed with chronic myeloid leukemia (CML). Most cases of CML are characterized by a chromosomal abnormality—the Philadelphia chromosome—in which genetic material is exchanged between chromosome 9 and chromosome 22. This exchange brings together two genes: BCR and ABL. The combination of these two genes into the single BCR-ABL gene results in the production of a protein that contributes to uncontrolled cell growth.
Recognition of the pivotal role of the BCR-ABL protein in CML led to the development of Gleevec, which blocks the activity of this protein. Gleevec produces high rates of remission among patients with chronic-phase CML, often with few side effects, and has dramatically changed the treatment of this disease.
Sprycel also targets the BRC-ABL protein, and has provided an important option for patients who are resistant or intolerant to Gleevec. Sprycel has not yet been approved for the initial treatment of CML.
To compare Gleevec and Sprycel for the initial treatment of CML, researchers conducted a study among 519 patients with newly diagnosed, Philadelphia chromosome-positive, chronic-phase CML. Patients were assigned to receive either Gleevec or Sprycel.
One of the main outcomes of interest was the complete cytogenetic response rate. A complete cytogenetic response is the complete disappearance of cells with the Philadelphia chromosome.
- After one year, the complete cytogenetic response rate was 77% among patients treated with Sprycel and 66% among patients treated with Gleevec.
- Rates of major molecular response (another marker of drug effectiveness) were 46% among patients treated with Sprycel and 28% among patients treated with Gleevec.
- Both drugs were generally well tolerated.
These results suggest that Sprycel may be more effective than Gleevec for the initial treatment of CML. Researchers will continue to follow the study participants in order to determine whether there are differences in progression-free and overall survival between study groups.
Reference: Kantarjian H, Shah NP, Hochhaus A et al. Dasatinib compared to imatinib in patients with newly diagnosed chronic-phase chronic myelogenous leukemia in chronic phase (CML-CP): 12 month efficacy and safety from the phase 3 DASISION study. Presented at the 2010 annual meeting of the American Society of Clinical Oncology. June 4-8, 2010. Chicago, IL. Abstract LBA 6500.