A new pill may soon offer people with rheumatoid arthritis an alternative to the injections and intravenous infusions that many rely on to treat their disease.

The drug, tofacitinib, is a twice-daily pill that works by turning down the body's immune attack on its own joints and organs. It works in a slightly different way than currently available treatments for rheumatoid arthritis, or RA.

"It's pretty important and pretty exciting, and some have described it as a biologic drug in a pill," says Jeffrey R. Curtis, MD, MPH, director of the Arthritis Clinical Intervention Program at the University of Alabama at Birmingham. Curtis worked on early trials of the treatment, but was not involved in the current research.

Biologics have revolutionized the treatment of RA, but they must be taken by injection or IV infusion. They are made from natural sources that use a biologic method, instead of a chemical method, to make them.

A pair of studies published in the New England Journal of Medicine show that the treatment works at least as well as Humira, an older biologic. Tofacitinib also reduced the number of swollen and painful joints in about twice as many patients compared to a placebo pill. That was true whether or not it was used in combination with methotrexate, the standard initial treatment for the disease.

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The Research

The studies included a total of more than 1,300 people with RA. Significant improvements in physical function were seen as early as the second week on the drug.

The studies didn't follow patients long enough to show whether tofacitinib might slow the physical destruction of the joints as other disease-modifying anti-rheumatic (DMARD) drugs do.

Both studies were paid for by Pfizer, the company that hopes to market the drug.

The FDA is weighing whether or not to approve tofacitinib, which works in a new way by blocking Janus kinase (JAK) enzymes inside cells. These enzymes help to control the chemical messengers that ramp up the immune response. Because the drug acts earlier in the immune response than most biologics, it has broader effects in the body.

Having a broader action sometimes makes a medication very powerful, but it can also increase the drug's potential for side effects since it affects more processes that take place downstream.

In the current studies, common side effects included upper respiratory tract infection, headache, and diarrhea. Tofacitinib was also linked to reduced white blood cell counts. White blood cells help the body fight infections.

And, patients taking the drug were more prone to viral and bacterial infections. Two patients on the highest doses of it developed tuberculosis.

Patients taking tofacitinib also had increased levels of LDL, the "bad" cholesterol. That's concerning since having RA roughly doubles a person's risk for heart disease.

"We don't know what it means if your cholesterol goes up a lot but inflammation goes down. Is that bad for the heart or the brain? Is it neutral? Is it good? We don't know," Curtis tells WebMD.

While those side effects are concerning, many other drugs that are already approved for RA have similar risks, Curtis says.

From Lab to Pharmacy

In May, a panel of advisors voted that despite the risks, the FDA should approve the drug. The agency was set to make its decision on the drug this month. But last week, the drug's manufacturer, Pfizer, announced that regulators had asked for more information and said they expected that the FDA's decision to be delayed.

Pfizer has not revealed how it will price the drug if approved, but it is expected to be expensive. The company said in a statement that it is committed to helping patients get access to the medication should it become commercially available.

If approved, tofacitinib is expected to be a blockbuster, generating sales of more than $1 billion a year, according to EvaluatePharma.

How much money it makes will depend on how doctors use it. Much of that will ride on the labeling the FDA might require. The agency could say that it should only be used in combination with methotrexate, for example. Or it could say that it should only be prescribed after other medications have failed.

"Will I use it in every patient? Probably not because I will still start with methotrexate," says researcher Roy Fleischmann, MD, a rheumatologist with the Metroplex Clinical Research Center in Dallas.

Fleischmann says it makes sense to start with methotrexate because it's a much less expensive drug. But he says for the roughly two-thirds of RA patients who don't respond to methotrexate or can't tolerate it because of side effects like mouth sores and hair loss, "I wouldn't hesitate to use this" as a stand-alone medication before trying a biologic.

Fleischmann has accepted grants and consulting fees from Pfizer. He was paid by the company to conduct the studies.
Other Opinions

But other experts think that how the drug should be used is still an open question.

"Will this drug get added to methotrexate? Will [it be a] substitute for methotrexate? Will it be used before a biologic or after a biologic failure? That will depend on experience, on talking to other doctors, on seeing what the insurance companies allow us to do," says Richard Furie, MD, a rheumatologist who is chief of the division of rheumatology at North Shore Long Island Jewish Health System in New York.

Other experts agree.

"While this is a pretty exciting drug because this is a new biologic pathway -- it's not just a 'me too' drug -- it does have issues with respect to, frankly, our total lack of understanding about who might be best suited to take it," Curtis says.