Pfizer has unveiled positive top-line results from the Phase 2b/3 ALLEGRO trial evaluating ritlecitinib, its once-daily oral treatment for alopecia areata.

Alopecia areata is an autoimmune disease characterized by the patchy hair loss on the scalp and may also affect the face and body.

The randomised, placebo-controlled, double-blind Phase 2b/3 study evaluated ritlecitinib in patients aged 12 years and above, with at least 50% scalp hair loss due to alopecia areata.

Patients in the study were randomised to receive ritlecitinib 50mg or 30mg (regardless of one-month initial treatment with once-daily 200mg dose), ritlecitinib 10mg or placebo.

The Phase 2b/3 ALLEGRO trial met the primary efficacy endpoint of improving scalp hair regrowth, as measured by SALT, a tool that measures the extent of scalp hair loss.

In the study, treatment using ritlecitinib 50mg and 30mg demonstrated less than or equal to 20% scalp hair loss after six months of treatment in more patients compared to placebo.

Ritlecitinib showed a safety profile that is consistent with previous studies.

Pfizer global product development chief development officer Michael Corbo said: “We are pleased by these positive results for ritlecitinib in patients with alopecia areata, a devastating and complex autoimmune disease for which there are currently no U.S. Food and Drug Administration (FDA) or European Medicines Agency approved treatments.

“We look forward to bringing this potential new treatment option to patients living with alopecia areata as soon as possible.”

Ritlecitinib belongs to a new investigational class of covalent kinase inhibitors that are highly selective for Janus kinase 3 (JAK3) and hepatocellular carcinoma (TEC) kinase family.

The drug has shown potential in blocking the activity of signalling molecules and immune cells that are thought to cause hair loss in people with alopecia areata, in laboratory studies.

In September 2018, the US FDA has granted Breakthrough Therapy designation for ritlecitinib to treat patients with alopecia areata.

It is also being studied for potential use in treating vitiligo, rheumatoid arthritis, Crohn’s disease and ulcerative colitis.

Pfizer intends to submit the full results of the study for scientific publication and presentation in future and will use the data, among others for future regulatory filings.