A new Pfizer drug marketed as Xeljanz (tofacitinib) is “a prescription medicine called a Janus kinase (JAK) inhibitor. XELJANZ is used to treat adults with moderately to severely active rheumatoid arthritis in which methotrexate did not work well. It is not known if XELJANZ is safe and effective in people with Hepatitis B or C. XELJANZ is not for people with severe liver problems.”
(This medication is in pill form versus injected/infused medications.) However, the FDA’s warning language changes. (LINK)
XELJANZ may cause serious side effects, including:
Hepatitis B or C activation infection in people who carry the virus in their blood. If you are a carrier of the hepatitis B or C virus (viruses that affect the liver), the virus may become active while you use XELJANZ.
May become active? Or not known?
One abstract in PUBMED states the viral reactivation problem:
Treatment considerations in patients with concomitant viral infection and autoimmune rheumatic diseases. (LINK)
Abstract (emphasis added)
Widespread use of immunosuppressive drugs, …in autoimmune rheumatic diseases (ARDs) has been found to be associated with the reactivation of underlying latent viruses. The clinical features of virus reactivation can sometimes mimic flare of the underlying ARDs. The correct diagnosis and management of such reactivation is crucial, as increasing the dose of immunosuppressive drugs to treat a presumed flare of underlying ARDs would probably be of no benefit, and it could exert a detrimental effect on the host. This review focused on the effects of immunosuppressive drugs on underlying chronic viral infections, particularly hepatitis B virus, hepatitis C virus, human immunodeficiency virus, …It also covered the effect of interferon-α, which is used to treat chronic hepatitis infection, and the induction of autoimmunity.
So in simple terms, a doctor may confuse virus reactions for ARD flare ups, prescribe a higher dose of medication, which in turn, can make latent undetectable viruses lethal again.
Pfizer is selling directly to patients in Martha Stewart magazine, and elsewhere, and the VA. Latent viral reactivation is a worrisome topic for veterans. Will all VA physicians screen for hepatitis before prescribing this medication? One VA fact sheet for patients makes no mention of hepatitis. And a VA professional monograph (LINK) simply states:
Viral reactivation was noted in the clinical studies with tofacitinib. The impact of tofacitinib on chronic viral hepatitis reactivation is unknown. Those who screened positive for hepatitis B or C were excluded from clinical trials.
So I would err on the side of caution and read the fine print if you have RA.