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Leukemia drug no help for mesothelioma patients, study finds

Dasatinib, a drug used to treat leukemia, showed “no activity” in patients with inoperable mesothelioma, say researchers who have just concluded a Phase II clinical trial at treatment centers around the country.


Dasatinib is a protein-tyrosine kinase inhibitor that works by blocking the action of an abnormal protein that signals cancer cells to multiply. It has shown to be effective as a so-called second-line treatment for two types of leukemia in patients for whom other treatments have failed.


In the mesothelioma trial, 46 patients were given 70 mg of dasatinib twice daily as part of a 28-day cycle. For half of the first 12 patients the drug was so toxic — provoking side effects such as pleural effusion, a buildup of fluid in the space that surrounds the lungs — that the starting dose was reduced to 50 mg twice a day.


To test the drug’s effectiveness, researchers measured the blood levels of several cancer growth indicators, including vascular endothelial growth factor and colony stimulating factor 1, or CSF-1. In more than 75 percent of the patients, the drug had no effect; progression-free survival after 24 weeks was just 23 percent.


Results of the trial were published in the Journal of Thoracic Oncology.


Mesothelioma is a rare disease caused by asbestos exposure. It attacks the mesothelium, a protective sac that covers the lung, abdomen and other organs. Mesothelioma is difficult to diagnose and even more difficult to treat.


Because standard therapies — chemotherapy, radiation, surgery — have shown few benefits, researchers have been exploring new drugs and drug combinations. Currently, the only treatment for inoperable mesothelioma known to extend survival times is a combination of pemetrexed and cisplatin, a chemotherapy drug. In one randomized trial, patients treated with pemetrexed and cisplatin had an estimated median survival of 12.1 months, as compared with 9.3 months in those treated with cisplatin alone.


Researchers are also investigating immunotherapies, like MORAb-009, a monoclonal antibody that stimulates the immune system to attack and destroy tumors that express mesothelin, a protein that can allow tumor cells to metastasize and grow.