Targeted Therapy for Leukemia May Prove a Breakthrough
CML, a cancer of the blood cells, accounts for 15-20% of all leukemia cases. An estimated 5,000 new cases of CML are diagnosed in the U.S. every year. The disease is usually first detected in individuals aged 50-60 and is relatively mild in its early stages. Late-stage CML, however, is deadly.
Current treatments of CML are not adequate. Bone marrow transplantation, the most effective therapy, is feasible in only about one-third of patients and is so toxic that some people die from the procedure itself. Other drugs for CML include interferon and hydroxyurea, both of which make patients very ill and are not very effective in all cases.
Based on earlier research, Druker and his team knew that the molecular pathway that leads to CML is based on an enzyme called BCR-ABL found in cancer cells. They tested several potential blockers of this enzyme and found the most promising is STI571, which will be called Glivec if it is approved by the FDA and marketed later this year by Novartis.
Just over two years ago, Druker and his team started testing this new drug on CML patients who had not responded to other therapy.
The results so far have been dramatic. Not only is the drug safe (side effects include only mild cases of nausea, muscle cramps, and eye puffiness), but it is also extremely effective, especially when first given during the early stage of the disease.
So far, relapse rates have only been high in those starting the drug later in the disease process, but there is some hope that combining STI571 with other therapies will control these relapses. Druker presented his award-winning findings last week in New Orleans at the annual meeting of the American Association for Cancer Research.
"For CML, this is a major breakthrough, and it validates the paradigm in cancer research of targeting the specific abnormalities that drive the course of cancer instead of [using] chemotherapy, which kills normal cells as well as the [cancer] cells," Druker tells WebMD. "Therapies coming in the future are just going to attack the cancer cells."