Chronic myeloid leukemia is usually treated first with a imatinib (Gleevec) that targets the protein BCR-ABL. If there is a recurrence due to resistance to the imatinib, individuals are then treated with dasatinib (SPRYCEL), which targets in BCL-ABR in a different way. Unfortunately, resistance to dasatinib is now being seen.

A study by researchers led by Charles Sawyers at Memorial Sloan-Kettering Cancer Center suggests that treating patients with both drugs in the beginning might decrease the chance of recurrence or at the very least, increase the time before such a relapse occurs. The authors suggest that treating patients with both drugs at first may prevent the emergence of the drug-resistant forms.

A third drug that can target both dasatinib- and imatinib resistant BCR-ABL is currently in trials.

Sprycel is an oral agent that has recently been approved by the FDA. It works by stopping the production of proteins involved in cancer growth.

The American Society of Hematology presented results that stated that treatment with Sprycel (dasatinib) provides better outcomes compared to giving higher doses of Gleevec (imatinib), in patients with chronic myeloid leukemia (CML), who have stopped responding to standard doses of Gleevec.

In the clinical trial the patients were either treated with Sprycel or increased doses of Gleevec to see who had the better response.

Study results indicated:

• Patients who had achieved a major anticancer response with the standard dose of Gleevec initially, achieved a 35 percent complete response to Sprycel, compared with only 7 percent of those treated with the increased doses of Gleevec.
• Patients who did not receive a major anticancer response with the standard dose of Gleevec initially, achieved a 44 percent major anticancer response to Sprycel, compared to only 7 percent of those treated with the increased doses of Gleevec.
• The main side effect of Sprycel was low levels of blood cells, which may be partly corrected with the use of Neulasta.

The research has concluded that Sprycel provides superior responses to increased-doses of Gleevec among patients with chronic-phase CML who have stopped responding to prior Gleevec therapy.