Rheumatoid arthritis is a serious and disabling autoimmune disease in which the immune system mistakenly attacks and destroys healthy body tissue. It affects more than 690,000 people in the UK, of which over 500,000 are women and around three-quarters are of working age. People with rheumatoid arthritis experience a range of symptoms, including pain and swelling in the joints, tiredness and depression which can affect their daily lives, from their ability to do basic everyday tasks like buttoning a shirt, to the possibility of having to stop work as a result of their condition. Though different treatments are available, there are still some people who may not respond to existing therapies or are intolerant to them.
Tofacitinib citrate belongs to a new class of medications known as JAK inhibitors. JAK inhibitors directly target the Janus kinase signalling pathway, working inside the cell by binding to the binding site on the JAK enzyme. This prevents JAK from activating the STAT proteins, interrupting the signalling channel and halting the message that ultimately produces the inflammatory response seen in rheumatoid arthritis.
Ailsa Bosworth, Founder and Chief executive of the National Rheumatoid Arthritis Society, said: “The prognosis for people diagnosed with rheumatoid arthritis has been completely transformed over the past two decades. But not every patient responds to their treatment and people can still experience significant limitations to what they can do and achieve because of their condition so, in spite of fantastic progress in rheumatology, there remains a need for different treatments. We therefore welcome any innovative new advances that can offer additional options.”
Tofacitinib citrate was the first Janus kinase inhibitor to be licensed for rheumatoid arthritis in the US and is currently licensed in over 50 countries. It has been prescribed to more than 55,000 patients worldwide. There have been 19 clinical trials to date and Pfizer has collected 8 years of safety data on the medicine.
The licensing of tofacitinib citrate is based on an extensive global development programme, including six pivotal trials - Oral Rheumatoid Arthritis Phase 3 TriaLs (ORAL) - and two open-label long-term extension (LTE) studies. These studies demonstrated that tofacitinib citrate is an effective treatment option showing a rapid onset of improvement in the signs and symptoms of rheumatoid arthritis, as measured by the percentage of patients reaching the American College of Rheumatology score (ACR20/50/70) compared to placebo-treated patients.
The safety profile of toficitinib citrate is similar to conventional synthetic DMARDs (csDMARDs) and biologics for rheumatoid arthritis, with the most common side-effects upper respiratory tract infections, headaches, diarrhoea and nasopharyngitis. The most common serious side-effects are infections. Tofacitinib citrate should not be used in patients with active infections, severe hepatic impairment and in pregnant and lactating women and should only be prescribed by specialist physicians.