Two separate phase III studies funded by Pfizer were published in August in the New England Journal of Medicine. In a six-month trial of 611 patients, both the 5 mg and 10 mg doses taken twice a day were more effective than placebo. And a yearlong study of more than 700 patients who had an inadequate response to methotrexate, patients taking 5 mg or 10 mg of tofacitinib twice a day had comparable improvement in symptoms to those taking adalimumab, and showed more improvement than those on placebo. 

The Food and Drug Administration approved the 5 mg dose of tofacitinib.

“It’s exciting to have a new drug that might be beneficial for people with rheumatoid arthritis, but we have a lot yet to learn,” says Patience White, MD, vice president for public health at the Arthritis Foundation and professor of medicine and pediatrics at George Washington University School of Medicine in Washington, D.C.

Many doctors and pharmacists agree, but caution that like all drugs, there are serious side effects to consider with tofacitinib. “People are often looking for the magic bullet, saying, ‘I hope this is the breakthrough and the drug with no side effects,’ and I would put cold water on that,” says pharmacist Donald Miller, professor and chair of the pharmacy practice department at North Dakota State University in Fargo. “It’s always nice to have different drugs available but it [won’t] necessarily be more effective or safer than the drugs already out there.”

Potential side effects include an increased risk of cancer; increased risk of serious infections including tuberculosis, pneumonia and upper respiratory tract infections; neutropenia, a condition marked by a very low white blood cell count that makes it hard to fight infection; increases in cholesterol levels and elevated liver enzymes.

Dr. White says that even though studies have outlined these side effects in clinical trials of a few thousand people, because tofacitinib is in a new class of medications, there’s no track record of similar medications to better understand how it will affect a wider group of patients.

“It’s always exciting when we make advances, and it is good to have many options. But there is a caveat of caution when we have a new drug. We don’t want to jump with our eyes closed,” Dr. White explains. “This is a whole new antibody. We don’t necessarily know all the things that it does.”

That’s why, in the short term at least, Dr. Ruderman says most rheumatologists, including him, are unlikely to use tofacitinib as a first-line drug.

“We are 10 years down the road with [TNF-alpha] inhibitors, and we are finally getting our arms around what the side effects are,” Dr. Ruderman says. “You don’t always know that after the clinical trials. A lot of that comes after the medication is on the market and a large number of patients take it. So I think a lot of rheumatologists will hang back and get a better feel for it once it’s on the market a while.”

Terry Moore, MD, director of the division of rheumatology at St. Louis University agrees, and says only time will tell where this new medication fits into the overall medical regimen.

“You have to deal with its cost and where insurance companies will put it on their priority list,” Dr. Moore says. “Leaving that aside, it probably will be used after methotrexate and maybe after a biologic you are familiar with. Maybe then you would go to this medication.”