In 2004, the Food and Drug Administration (FDA) approved the use of the drug pemetrexed disodium, trade name Alimta®, for use in combination with the platinum compound, cisplatin, for the treatment of mesothelioma using chemotherapy. Pemetrexed disodium, also known as just pemetrexed, was approved by the FDA specifically for the treatment of malignant pleural mesothelioma. Pemetrexed kills cancer cells by inhibiting the synthesis of certain enzymes that are necessary for cells to grow. The enzymes, thymidine and purine, are the enzymes that pemetrexed targets. The drug has the ability to both target and block enzymes that cancer cells need in order to reproduce through cell division. Mesothelioma is considered a rare disease since only about 2,000 new cases are diagnosed in the US each year. In the US, a disease is considered to be rare if less than 200,000 people are affected by it. Drugs developed to treat such rare diseases are termed orphan drugs. The Orphan Drug Act gives the first sponsor to obtain marketing approval for an orphan drug, the right to a 7-year exclusive marketing period. The company, Eli Lilly and Company Pharmaceuticals of Indianapolis Indiana has that right to market and distribute the orphan drug, Alimta®. Malignant pleural mesothelioma is a cancer of the pleura membrane that covers the lungs and the walls of the chest cavity. The cancer is characteristic of some people who have had a history of asbestos exposure. Asbestos fibers that are inhaled become lodged in the lung and then attach themselves to the lining of the chest wall. Cancer tumors then form and grow on the membranes of the sensitive organs.  A clinical trial evaluated the effects of treating mesothelioma patients with the cisplatin/pemetrexed combination versus treating patients with cisplatin alone. Patients who received the cisplatin/pemetrexed combination treatment lived for approximately 12 months following diagnosis, which is three months longer than patients that are treated with cisplatin alone. With cisplatin treatment alone, patients live for approximately 9 months after diagnosis. The cisplatin/pemetrexed combination is not expected to cure mesothelioma, however, the combination has been shown to prolong life, reduce pain and improve the quality of life for patients, particularly those patients with advanced pleural mesothelioma and who are not able to sustain surgery to treat the disease.   Pemetrexed offers some side effects, which include nausea, diarrhea, fatigue, mouth sores, vomiting and low blood counts. Patients may be given a regiment of vitamin B12 and folic acid to help alleviate these side effects. Patients may also develop rashes in response to the chemotherapy treatment. In an effort to prevent rashes from developing, doctors will prescribe a corticosteroid or a synthetic substitute for corticosteroids. A corticosteroid is a steroid that is obtained from the cortex of the adrenal gland. Patients may also experience infection as pemetrexed may cause bone marrow suppression, which increases the chance of infection. Fever, chills, diarrhea and mouth ulcers indicate that infection may have set in.  The FDA requires warning labels for pemetrexed to indicate that the drug could suppress the functioning of bone marrow. The effects of which are:·         Anemia as a result of low red blood cell counts·         Neutropenia as a result of low white blood cell counts·         Thrombocytopenia, which is a decrease in platelets in the blood.The FDA advises doctors to warn patients of these affects, perform appropriate testing and adjust dosages accordingly.