Safety and Regulatory Guidance for JAK Inhibitors in Rheumatoid Arthritis

Pulmonary Embolism Risk

In patients > 50 years old with cardiovascular risk factors, tofacitinib 10 mg twice daily is associated with a five‑fold higher incidence of pulmonary embolism compared with TNF‑inhibitor therapy. (U.S. Food and Drug Administration safety data) [Evidence level: moderate; observational data] 1

The U.S. FDA requires documented failure of, or contraindication to, a TNF‑α antagonist before initiating any JAK inhibitor (upadacitinib or tofacitinib) for rheumatoid arthritis. (Regulatory labeling) [Evidence level: high; regulatory authority] [2][3]
This restriction is based on the ORAL Surveillance trial, which demonstrated increased major adverse cardiovascular events and venous thromboembolism in older RA patients with cardiovascular risk factors receiving JAK inhibitors. (Trial data) [Evidence level: high; randomized controlled trial] [4][3]

The EMA advises cautious first‑line use of JAK inhibitors in patients ≥ 65 years, current or former smokers, those with a history of cardiovascular disease, or a history of malignancy. (EMA guidance) [Evidence level: moderate; expert consensus] 2

Baseline and periodic (every 1–3 months) monitoring of complete blood count, liver enzymes, and lipid profile is required for patients treated with either upadacitinib or tofacitinib. (FDA monitoring recommendation) [Evidence level: high; regulatory guidance] 1

Tofacitinib 10 mg twice daily should be avoided in patients with heightened VTE risk (e.g., heart failure, active malignancy, recent surgery, inherited coagulation disorders, prior thromboembolism, or hormonal therapy). (Safety warning) [Evidence level: moderate; safety database] 1

Prior to initiating either JAK inhibitor, herpes zoster vaccination is recommended for patients ≥ 50 years or those at high risk, with a minimum interval of 4 weeks after a live vaccine before starting therapy. (Infection prevention guideline) [Evidence level: moderate; expert consensus] 1

Using upadacitinib or tofacitinib as first‑line therapy without prior TNF antagonist failure violates FDA labeling. (Regulatory restriction) [Evidence level: high; regulatory authority] [2][3]

The European League Against Rheumatism (EULAR) recommends tofacitinib as a targeted synthetic DMARD (tsDMARD) to be added after failure of conventional synthetic DMARDs in patients with unfavorable prognostic markers 5, 6
Tofacitinib demonstrates robust efficacy superior to placebo and comparable to methotrexate across multiple outcome measures, with an odds ratio of 2.44 (95% CI 1.97-3.02) for ACR20 response rates compared to placebo 7, 8
Tofacitinib effectively reduces signs and symptoms of rheumatoid arthritis, improves physical function, and appears to reduce structural damage progression 7, 8

The American College of Rheumatology and EULAR note that tofacitinib is associated with an increased risk of herpes zoster infection, which occurs more frequently than with TNF inhibitors 9, 5, 10
Tofacitinib carries a critical safety signal regarding venous thromboembolism (VTE) and pulmonary embolism, particularly at the 10 mg twice daily dose but also present at the approved 5 mg twice daily dose 5, 10
VTE risk is especially elevated in patients with previous thromboembolic events, high body mass index, hormone replacement therapy, and advanced age 5, 10
JAK inhibitors, including tofacitinib, should be used with caution in patients at high risk for thromboembolic events 5, 10

EULAR recommends starting with conventional synthetic DMARDs (particularly methotrexate) as first-line therapy, then adding a biologic DMARD or tsDMARD (including tofacitinib) if treatment targets are not achieved 5, 6
Tofacitinib can be used as monotherapy when methotrexate is contraindicated or not tolerated 6

The EULAR task force determined that bDMARDs and tsDMARDs have on average similar efficacy, with no preference given to any agent based solely on efficacy 5, 10
Despite upadacitinib's greater JAK1 selectivity, it appears to have a similar safety profile to less-selective JAK inhibitors, including VTE risk 5, 10
All three JAK inhibitors (tofacitinib, baricitinib, and upadacitinib) share similar safety concerns, including increased herpes zoster infections, VTE and pulmonary embolism risk, infections, and hematologic abnormalities 5, 6, 10