Research Predicts Mesothelioma Patients To Benefit From Pemetrexed

A study by researchers at the University of Colorado Cancer Center may help doctors predict which mesothelioma patients will benefit from the chemotherapy drug pemetrexed. Mesothelioma is an aggressive cancer of the lining of the chest and abdominal cavities caused by inhaling asbestos.

Standard treatments for malignant mesothelioma include the chemotherapy drugs pemetrexed, cisplatin, and bevacizumab.

Pemetrexed works by inhibiting the enzyme thymidylate synthase (TS), which cancer cells need to reproduce. Still, mesothelioma is often resistant to chemotherapy drugs. Pemetrexed does not halt the growth of tumors in all mesothelioma patients. Researchers have hypothesized that patients with low levels of the enzyme TS may respond best to the drug.

New research published in the Journal of Thoracic Oncology sheds more light on the use of the enzyme TS as a biomarker for therapeutic response in mesothelioma patients. The researchers, led by Dr. Daniel C. Christoph, an international postdoctoral researcher, report that low levels of TS are predictive of mesothelioma patients’ response to pemetrexed only in combination with high levels of a second enzyme, FPGS. High levels of FPGS permit pemetrexed to remain inside cells longer, allowing the drug more time to work, they observed.

Christoph and colleagues tested 84 samples of mesothelioma in which patients had been treated with pemetrexed. Patients with low TS and high FPGS had more response to pemetrexed and survived longer.

According to a University of Colorado Cancer Center release, the current study provides the preclinical work necessary to justify exploring the predictive power of the two enzymes in mesothelioma patients.

“The hope is that oncologists could test a patient for TS and FPGS levels and so discover if the patients should be treated with pemetrexed or if another therapy might be more appropriate,” Dr. Christoph, the lead author of the research, said in a prepared statement.

Approximately 2,500 to 3,000 people are diagnosed with mesothelioma each year in the United States. Asbestos causes an estimated 107,000 preventable deaths each year around the world, according to the World Health Organization.

Most people diagnosed with mesothelioma are older workers, retired workers or veterans who were exposed to asbestos fibers in the workplace or military service. The disease typically takes 20 years to 40 years before sufferers notice symptoms such as pain beneath the ribs and difficulty breathing. The cancer often has reached an advanced stage before doctors diagnosed it correctly.

Researchers continue to seek more effective treatments for mesothelioma and more accurate predictors of which patients will respond to which treatments,including chemotherapy, radiation and surgery.

For more information about mesothelioma treatments, click here.