Experimental Rheumatoid Arthritis Drug Faces FDA Advisory Panel

ATsai Editor

    Pfizer officials will go before an advisory panel Wednesday to determine if the benefits of its  new rheumatoid arthritis (RA) drug, tofacitinib, outweigh the side effects.  Although the Food and Drug Administration (FDA) is not required to follow the advice of its advisory panels, it generally does. Industry experts expect the panel to give the drug a favorable vote, but the FDA will make a final ruling in August.


    Analysts suggest that the FDA would likely approve the drug as a third option treatment to be used if existing medications have proven ineffective. According to one industry analyst, the FDA may take a stricter approach to approving tofacitinib than with previous rheumatoid arthritis drugs because there already are good drugs on the market and also due to concerns about its potential side effects.

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    What is Tofacitinib?

    Tofacitinib is a chemical pill that would be taken twice a day. It works by inhibiting the enzyme Janus kinase 3 (JAK3), which blocks signals to the cell nucleus that otherwise would activate an immune response and cause inflammation and pain.  The pill is undergoing clinical trials for the treatment of rheumatoid arthritis, but is also being studied to treat other conditions, such as inflammatory bowel disease, psoriasis and dry eye.


    How is it different from drugs currently on the market?

    Tofacitinib is the first of 11 drugs in a new category called JAK inhibitors to be at this stage of clinical development. Biologics such as Enbrel, Humira and Remicade, which are currently on the market, are TNF-inhibitors that need to be injected. One big plus for tofacitinib is that it’s a pill, rather than a drug that needs to be injected, which is the case with all of the existing RA medications. It’s also possible that the new drug would be less expensive than other biologic drugs.


    What are the side effects and FDA concerns?

    The major side effects for patients in the clinical trials include higher-than-normal cholesterol and liver enzyme levels, and an increased risk of infection and lymphoma. FDA staff also reported that the data did not show the pill stopped RA from progressing, which is an important measure in the discussion of risk versus benefit.


    How would this drug be used in an RA treatment regimen?

    Pfizer plans to first market the drug to patients who have failed on TNF-inhibitors or methotrexate. It estimates that 30 to 40 percent of RA patients do not respond to TNF-inhibitors and says tofacitinib would be answering an unmet need. Pfizer eventually hopes to gain approval for the drug as a first-line option for patients, or a second option behind methotrexate, but notes that this will only happen as doctors become more comfortable with the safety and efficacy of the drug.

Published On: May 08, 2012