Alimta (pemetrexed disodium)

Alimta is a folate antimetabolite chemotherapy drug (chemically similar to folic acid) that is used in the treatment of malignant mesothelioma and non-small cell lung cancer.  Folic acid (also known as Vitamin B9 or Folacin) and Folate (the naturally occurring form) are forms of the water-soluble Vitamin B9.  Alimta was developed by Edward Taylor, a professor emeritus of chemistry at Princeton University.

Alimta works by inhibiting cell growth with the goal of preventing tumor metastasis (the spread of cancer to other parts of the body).  Alimta inhibits three enzymes (thymidylate synthase, dihydrofolate reductase and glycinamide ribonucleotide formyl transferase) that are used in the synthesis of purine and pyrimidine, necessary for the formation of DNA and RNA. By preventing the formation of DNA and RNA, Alimta is able to inhibit cell growth, ideally stopping tumor metastasis.  Alimta was approved by the Food and Drug Administration in 2004, following eleven years of clinical trials.  As of May 2009, Alimta continues to be tested in clinical trials.

Alimta is administered intravenously once every three weeks for a ten-minute period. Compared with other chemotherapy drugs, Alimta has a delivery method that is much more convenient. Before beginning treatment with Alimta, a number of preparatory steps must be taken:

    * Take a folic acid pill every day, starting five to seven days before beginning treatment and continuing until 21 days after the last Alimta cycle is complete.
    * Receive a vitamin B12 shot from a doctor. Another B12 shot will be received every nine months.
    * An oral steroid will be taken twice a day on the day before, the day of and the day after treatment. Typically dexamethasone, the oral steroid minimizes the risk of Alimta side effects.

Alimta as a Single Agent

As a single agent, Alimta is indicated for the treatment of patients with locally advanced or metastatic non-small cell lung cancer (following prior chemotherapy treatments).

A number of side effects are associated with Alimta as a single agent.  These side effects fall into two distinct categories:

    * Patient-felt toxicities:  fatigue, nausea and vomiting.
    * Paper toxicities:  paper toxicities are dangerous because they refer to side effects that you are physically unaware of, such as blood cell changes.

Alimta and Cisplatin

When used in combination with platinum-based cisplatin, Alimta is the only FDA approved drug used for the specific treatment of malignant pleural mesothelioma.

The combination of Alimta and cisplatin can produce a wide variety of adverse side effects, some of which include:

    * Low blood counts
    * Gastrointestinal upset
          o Nausea / vomiting
          o Anorexia (loss of appetite)
          o Diarrhea
    * Fatigue
    * Mouth sores
    * Rash

Alimta Clinical Trials

Clinical trials comprise four phases:

    * Phases I & II test the safety of a drug.
    * Phase III compares the drug with a treatment method that has been proven effective and is the last phase before applying to the FDA for approval.
    * Phase IV coincides with the marketing of the drug after FDA approval.

Clinical trial results suggest that Alimta, when used in combination with cisplatin, improves the median survival rate for patients suffering from malignant pleural effusion.  Patients who were treated with Alimta and cisplatin survived about three months longer than patients treated only with cisplatin.

Although a survival rate improvement of three months might not seem like much, it is a step in the right direction.

As of May 2009, Alimta continues to be tested in clinical trials.  There are currently 16 mesothelioma clinical trials using this drug in combination with other drugs to try to improve treament results for mesothelioma patients.