New treatments for Chronic Myelogenous Leukemia (CML)

New treatments for Chronic Myelogenous Leukemia (CML)

In the United States, about 5500 patients per year will be diagnosed with CML; a chronic leukemia associated with high white blood cell counts and other blood count abnormalities; which in the past was only curable with a bone marrow transplant.  However for the last 12 years, treatment with an oral drug called imatinib (brand name Gleevec), which belongs to a class of drugs called tyrosine kinase inhibitors, has been a major breakthrough in that many patients who were started on Gleevec saw their chronic leukemia disappear. Patients do have to remain on the medication indefinitely, otherwise the chronic leukemia could come back.

Over the years, two other oral drugs (dasatinib and nilotinib) which are even more successful than imatinib have been approved for the treatment of CML. However, there are CML patients who do not see their chronic leukemia go away with Gleevec or even when treated with dasatinib or nilotinib.

For those patients, treatment with bosutinib may be an option. The drug was approved by the FDA in September 2012 for patients who did not benefit from treatment with imatinib,dasatinib or nilotinib. Patients who had been on imatinib, in particular, experienced significant improvement of their chronic leukemia when they took bosutinib.

When CML cells become resistant to standard treatment, it is usually through specific mutations of certain proteins within the cell. One particularly feared mutation is the T315I mutation which confers resistance to all oral anti-CML medications. There is a promising new drug called ponatinib which in one study resulted in complete normalization of blood counts of all patients who had the T315I mutation. I am happy to report that ponatinib received FDA approval on December 7, 2012 giving patients with standard-treatment-resistant CML a promising treatment option. The brand name of ponatinib is going to be Iclusig.

Lastly, the FDA recently approved another drug for the treatment of CML called omacetaxine (brand name Synribo) which has to be injected under the skin twice daily on certain days of the month. It may play a role in the treatment of patients who cannot tolerate any of the other FDA-approved anti-CML drugs or those who have not responded to them.