Is tofacitinib/Shangjie a biological agent?

Although Tofacitinib plays a role similar to biological agents in the treatment of autoimmune diseases such as rheumatoid arthritis, psoriatic arthritis, ulcerative colitis (UC), ankylosing spondylitis, etc., from the perspective of drug classification, it is not a biological agent, but a small molecule oral targeted drug.

Biological agents are usually protein drugs produced through genetic engineering technology, such as monoclonal antibodies, recombinant receptor fusion proteins, etc. These drugs have large molecular weights and must be administered by injection or infusion, and often require cold chain storage. The structure of tofacitinib is a synthetic small molecule compound with a molecular weight much smaller than biological agents. It can be absorbed orally, and the storage and transportation conditions are relatively simple.

Although different in form, the therapeutic effects of tofacitinib are somewhat comparable to biologics. It mainly blocks the signal transmission of multiple inflammatory factors by selectively inhibiting the JAK pathway to achieve the purpose of inhibiting immune overreaction. This is different from the mechanism by which biological agents directly block a specific inflammatory factor (such as TNF-α, IL-6), but the ultimate goal is to reduce inflammation and joint destruction.

In clinical application, tofacitinib is often used as an alternative after traditional drugs such as methotrexate are ineffective or intolerable, and can also be used as a supplement or transition to biological agents. Compared with biological agents, tofacitinib has the advantages of oral convenience, relatively rapid onset of action, and high patient compliance, and is especially suitable for long-term management. But at the same time, it also has side effects such as increased risk of infection and changes in blood lipids. Therefore, doctors will weigh the patient's overall condition when making a choice.

From the perspective of market positioning, tofacitinib fills "the gap between chemical small molecule drugs and biological agents." It allows some patients to obtain therapeutic effects similar to biological agents without relying on long-term injections, and also promotes the development of oral targeted immunomodulatory drugs. As more JAK inhibitors become available, tofacitinib represents a new direction in rheumatoid immunotherapy in the future.

Reference materials:https://www.xeljanz.com/