New Drug Aims at Chronic Myeloid Leukemia That Resists Treatment

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Targeted therapy for chronic myeloid leukemia is one of the great success stories of cancer treatment.

CML is driven by an abnormal chromosome that creates a hybrid gene called bcr-abl that produces a protein which causes and fuels the disease. This abnormality is called the Philadelphia chromosome because it was discovered by scientists in that city.

Only half of CML patients survived to the five-year mark. Imatinib, known as Gleevec, changed all of that. Scientists at the Oregon Health Sciences University discovered the drug's effect on CML and worked with Novartis, the drug's owner, to develop Gleevec. Clinical trials were conducted largely at MD Anderson.

The result: 90% of patients survive to five years. However, some patients have their disease grow resistant to the drug. And for those with a mutation called T315I, the drug does not work. This held true for second-generation drugs -- nilotinib (Tasigna) from Novartis and dasatinib (Sprycel) from Bristol-Myers Squibb.

A new, experimental drug called ponatinib appears to hit all versions of CML. Jorge Cortes, M.D., professor in the Department of Leukemia at MD Anderson, presented Phase I results Monday morning at the American Society of Hematology Annual Meeting in Orlando.
Developed by ARIAD Pharmaceuticals, ponatinib cleared CML cells from the blood in 30 of 32 patients in the chronic, early stage of the disease. All 11 chronic phase patients with T315I had that hematological response. Eight had complete cytogenetic response, which means absence of malignant cells in the bone marrow.

"Ponatinib seems to be filling the gap we had for patients who right now have no good treatments left," Cortes says. "We are very encouraged by such strong results in the Phase I setting and have begun a pivotal Phase II clinical trial."

For more detail on results please see the abstract

American Society of Hematology 2010 Meeting and Expo

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