Tofacitinib, sold under the brand Xeljanz, Neojanz among others, is a medication used to treat rheumatoid arthritis, psoriatic arthritis, ankylosing spondylitis, polyarticular-course juvenile idiopathic arthritis, and ulcerative colitis. It is a janus kinase (JAK) inhibitor, discovered and developed by the National Institutes of Health and Pfizer. Common side effects include diarrhea, headache, and high blood pressure. Serious side effects may include infections, cancer, and pulmonary embolism. In 2019, the safety committee of the European Medicines Agency began a review of tofacitinib and recommended that doctors temporarily not prescribe the 10 mg twice-daily dose to people at high risk for pulmonary embolism. The U.S. Food and Drug Administration (FDA) also released warnings about the risk of blood clots. An important side effect of Jakinibs is serious bacterial, mycobacterial, fungal and viral infections. In the phase III trials of tofacitinib among opportunistic infections, pulmonary tuberculosis (TB) was reported in 3 cases all of which were initially negative upon screening for TB. It was approved for medical use in the United States in November 2012. The extended-release version was approved in February 2016. It is available as a generic medication.
Medical uses
Rheumatoid arthritis Tofacitinib citrate is approved for medical use in the United States with an indication "to treat adults with moderately to severely active rheumatoid arthritis who have had an inadequate response to, or who are intolerant of, methotrexate". In the European Union, in combination with methotrexate, tofacitinib citrate is indicated for the treatment of moderate to severe active rheumatoid arthritis (RA) in adults who have responded inadequately to, or who are intolerant to one or more disease-modifying antirheumatic drugs. It can be given as monotherapy in case of intolerance to methotrexate or when treatment with MTX is inappropriate.
Ulcerative colitis In May 2018, the FDA approved tofacitinib citrate "for the treatment of adult patients in the U.S. with moderately to severely active ulcerative colitis." Tofacitinib citrate is the first oral JAK inhibitor approved for use in chronic ulcerative colitis.
Adverse effects Tofacitinib was initially not approved by European regulatory agencies because of concerns over efficacy and safety, although by 2018, the European Commission had approved it. Animal studies with tofacitinib conducted prior to human trials showed some carcinogenesis, mutagenesis, and impairment of fertility. The most commonly reported adverse reactions during the first three months in controlled clinical trials (occurring in 2% or more of patients treated with tofacitinib citrate monotherapy or in combination with DMARDs) were upper respiratory tract infections, headache, diarrhea, and nasopharyngitis (the "common cold"). Tofacitinib is required by the FDA to have a boxed warning on its label about possible injury and death due to problems such as infections, lymphoma, and other malignancies, which can arise from use of this drug. Serious infections leading to hospitalization or death, including tuberculosis and bacterial, invasive fungal, viral, and other opportunistic infections, have occurred in patients receiving tofacitinib. Epstein Barr virus-associated post-transplant lymphoproliferative disorder has been observed at an increased rate in renal transplant patients treated with tofacitinib while on immunosuppressive medications. Patients are warned to avoid use of tofacitinib citrate during an "active serious infection, including localized infections". Doctors are advised to use it with caution in patients who may be at increased risk of gastrointestinal perforations. Laboratory monitoring is recommended due to potential changes in lymphocytes, neutrophils, hemoglobin, liver enzymes, and lipids. Tofacitinib claims to have no contraindications, but doctors are advised to reduce the patient's dosage when combined with "potent inhibitors of cytochrome P450 3A4 (CYP3A4)," such as ketoconazole, or one or more combined medications that result in both moderate inhibition of CYP3A4 and potent inhibition of CYP2C19 such as fluconazole. Furthermore, immunizations with live vaccines should be avoided by tofacitinib users. According to postmarketing research, tofacitinib may also increase the risk for pulmonary embolism. Prescribers should consider risk factors for pulmonary embolism, including age, obesity, smoking, and immobilization before prescribing this medication. Patients taking this medication, irrespective of indication or risk factors, should be monitored for signs and symptoms of pulmonary embolism.
Mechanism It is an inhibitor of the enzyme janus kinase 1 (JAK1) and janus kinase 3 (JAK 3), which means that it interferes with the JAK-STAT signaling pathway, which transmits extracellular information into the cell nucleus, influencing DNA transcription. In a mouse model of established arthritis, tofacitinib rapidly improved disease by inhibiting the production of inflammatory mediators and suppressing STAT1-dependent genes in joint tissue. This efficacy in this disease model correlated with the inhibition of both JAK1 and JAK3 signaling pathways, suggesting that tofacitinib may exert therapeutic benefit via pathways that are not exclusive to inhibition of JAK3.
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