Some leukemias face new medicines

2001/06/22 Galarraga Aiestaran, Ana - Elhuyar Zientzia

• Genetika
• Medikuntza

Chronic myeloid leukemia accounts for 15% of all leukemias and STI-571 was primarily intended for this type of leukemia. This drug inhibits enzymes essential in the growth of leukemia. Virtually all patients with chronic myeloid leukemia in their early days have significantly improved with this drug. However, those who have already developed leukemia have not obtained the same result. Although the patient's situation is initially improved, 80% of patients retract before a year.

To find the reason for this resistance, University of California researcher Charles Sawyer and his team analyze enzymes that inhibit drugs. The gene producing these enzymes is the oncogene Bcr-{, whose enzymatic activity was studied in the tumor cells of 11 patients who became ill again. Unlike what researchers expected, enzymatic activity was very high in all cells (it was considered that being genetically unstable tumor cells, its effect would be cancelled by another change). In 6 patients, the reason for resistance was the mutation of the Bcr-> gene. This mutation allowed tumor cells to maintain an essential enzyme activity in tumor growth. In three other patients, the tumor acquired the ability to generate copies of the gene and produce more enzymes than the drug could attack.

In one way or another, resistance is due to changes in the gene that produces the enzymes that are the subject of the drug. Now, to inhibit these enzymes you will need to look for other medicines, since STI-571 is not as effective as you want in all cases.