About JAK Inhibitors

After decades of no new treatments, there is hope for people with moderate to severe alopecia areata: Janus kinase (JAK) inhibitors. These are immunomodulatory drugs. They modify the immune system by curbing certain enzymes called cytokines.  

 When you have alopecia areata, your immune system attacks your hair follicles, disrupting the growth cycle. JAKs are blood protein messengers that stimulate the immune cells, producing blood proteins called cytokines. If there are too many cytokines, you get inflammation. Taking a JAK inhibitor decreases the number of cytokines, decreasing inflammation. If the inflammation decreases enough, the hair may grow back.  

A case report published in 2014, was the first to show a JAK inhibitor, tofacitinib (Xeljanz®), could successfully treat alopecia areata. Since then, many studies have shown that JAK inhibitors can effectively promote hair regrowth in alopecia areata.  

Doctors already prescribe JAK inhibitors for a number of conditions, including rheumatoid arthritis, atopic dermatitis, and ulcerative colitis. Since 2022, the FDA has approved three JAK inhibitors— Olumiant® (baricitinib,) Litfulo® (ritlecitinib,) and Leqselvi® (deuruxolitinib)  —as treatments for severe alopecia areata (see below). Xeljanz® (tofacitinib), another JAK inhibitor, is an older medication still prescribed off-label for alopecia areata. Other JAK inhibitors, such as upadacitinib (RINVOQ®), are currently in clinical trials.  

JAK inhibitors are sometimes combined with other treatments, such as oral minoxidil or intralesional (meaning an injection directly into the area of hair loss) corticosteroids. 

Olumiant

In June 2022, the FDA approved the JAK inhibitor baricitinib (​Olumiant®), a daily pill, for adults with severe alopecia areata. This is the first time the FDA has specifically approved an oral drug for this disease. Olumiant was first approved in 2018 to treat rheumatoid arthritis.  

Clinical trials showed ​​that 32% to 35% of patients with extensive alopecia areata who took Olumiant at the 4 mg/kg dose had hair regrowth covering 80% or more of their scalp after 36 weeks of treatment. Longer term studies showed that hair regrowth continued over time with Olumiant treatment. Some people showed a delayed response to treatment initially but achieved hair regrowth over a longer period of time. After continuous treatment with Olumiant for 2 years (104 weeks), 90% of patients had hair regrowth covering 80% or more of their scalp.  

Litfulo

In June 2023, the FDA approved another JAK inhibitor, LITFULO® (ritlecitinib), for the treatment of severe alopecia areata in adults and adolescents ages 12 and up. Litfulo is the first approved treatment for individuals under the age of 18. Litfulo is an oral medication taken once daily. In a clinical trial, treatment with Litfulo was significantly more effective in achieving hair regrowth to 80% or more scalp hair coverage compared to placebo.  

Other JAK inhibitors may be prescribed off-label for children and several investigations have shown their effectiveness in children. 

Leqselvi

In July 2024, the FDA approved a third JAK inhibitor, deuruxolitinib (Leqselvi®), for the treatment of alopecia areata in adults 18 years and older. Leqselvi is a new oral medication that is taken two times per day.  

Leqselvi was tested in two large placebo-controlled Phase 3 clinical trials of more than 1,200 patients with at least 50% scalp hair loss. In one of the clinical trials, one-third of study participants (33%) receiving 8 mg of Leqselvi twice daily for 24 weeks achieved 80% or greater scalp hair regrowth, compared to less than 1% of the participants taking placebo.  

As of November 2024, Leqselvi’s commercial release is on hold due to a court injunction following a patent infringement lawsuit. 

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