Australian Researchers Study Effectiveness of Front-line Mesothelioma Drug
Researchers are still working to improve the medications used to treat malignant pleural mesothelioma, a stubbornly aggressive respiratory cancer caused by exposure to asbestos. One of the mesothelioma treatment chemotherapy drugs that doctors often prescribe patients to kill cancer cells and shrink tumors is pemetrexed, an antifolate. Certain key enzymes in folic acid fuel the growth of mesothelioma tumors in the lining of the lungs. Antifolate drugs work by causing a deficiency of those enzymes, thus choking the cancer’s food supply and disrupting the metabolic processes of the cancer cells.
Pemetrexed, which is manufactured by Eli Lilly and sold under the brand name Alimta, is the only medicine so far approved by the Food and Drug Administration specifically to treat mesothelioma. Doctors began administering it in combination chemotherapy with Cisplatin, an older cancer drug, in 2003 following reports of its effectiveness in knocking back mesothelioma.
In a recent study published in the Asia Pacific Journal of Clinical Oncology, researchers at the University of Western Australia analyzed the medical records of 62 mesothelioma patients treated from 2004 to 2007 with pemetrexed alone or in combination with other drugs. The state of Western Australia has one of the highest occurences of malignant pleural mesothelioma because many workers in the region of 2 million people were employed in mining and production of crocidolite asbestos from 1943 to 1966.
The researchers reported that the mesothelioma patients, nearly all of whom were males, tolerated the chemotherapy well and received some benefit from the treatment for mesothelioma lung cancer. But the patients lived on average less than one year after the start of pemetrexed-based chemotherapy. That is a somewhat shorter survival than that reported in phase III clinical trials, they said.
After earlier phase III trials, researchers at the University of Chicago in 2002 said that patients on combination therapy including pemetrexed lived longer and experienced less pain than those on an older drugs. Those trials showed that the tumors shrank in 41 percent of patients receiving a combination of pemetrex and cisplatin compared to tumor shrinkage among 17 percent of patients receiving cisplatin alone.
The Australian researchers said that further research is required to identify patients who might benefit from pemetrexed based on molecular response to the drug.
An aggressive cancer, mesothelioma strikes 2,500 to 3,000 Americans each year. Most people who receive a mesothelioma diagnosis —either malignant pleural mesothelioma or malignant peritoneal mesothelioma— were exposed to asbestos in the workplace. Microscopic particles of asbestos inhaled into the lungs can lodge there and cause disease decades later. Symptoms of asbestos-related disease typically appear 20 to 50 years after exposure.
