The Food and Drug Administration has approved the second drug in two months for treating chronic myeloid leukemia (CML). On Oct. 26, Synribo (omacetaxine mepesuccinate) was approved to treat adult patients whose CML has progressed after treatment with at least two tyrosine kinase inhibitors (TKIs), such as Gleevec (imatinib), Sprycel (dasatinib) and Tasigna (nilotinib). The previous drug approval came in September for the tyrosine kinase inhibitor Bosulif (bosutinib).When disease progresses after treatment with multiple TKIs, it can be more difficult to treat and options become more limited. There are some mutations that don't respond well to TKIs. Synribo works by blocking certain proteins that promote cancer cell growth and provides another option after TKI treatment.Synribo's effectiveness was established in trials with a cohort of patients whose disease had progressed despite treatment with TKIs, and all patients received Synribo. In the group of 76 chronic phase CML patients, effectiveness was determined by a reduction in the number of cells that have the Philadelphia chromosome genetic mutation, which most CML cells have. After an average of 3.5 months of treatment, 14 of the 76 patients had a response that lasted for a median of 12.5 months. For those patients in the accelerated phase, effectiveness was measured through a normalization of white blood counts or absence of leukemia. Five out of the 35 patients had a response in an average of 2.3 months, and the response lasted for a median of 4.7 months.Synribo is injected under the skin twice a day for 14 days over the course of a 28-day cycle. Once the white blood cell count normalizes, Synribo is then given twice a day for seven consecutive days for a 28-day cycle, and the patient continues with Synribo as long as he or she has a clinical benefit. Common side effects include low platelet, red and white blood cell counts; diarrhea; nausea and fatigue.For more information, please visit synribo.com or call 800-896-5855.