What is this summary about?

This is a summary of the results of the ALLEGRO phase 2b/3 clinical trial, originally published in The Lancet. ALLEGRO-2b/3 looked at how well and safely the study medicine, ritlecitinib, works in treating people with alopecia areata ('AA' for short). The immune system protects your body from outside invaders such as bacteria and viruses. AA is an autoimmune disease, meaning a disease in which one's immune system attacks healthy cells of the body by mistake. In AA, the immune system attacks hair follicles, causing hair to fall out. AA causes hair loss ranging from small bald patches to complete hair loss on the scalp, face, and/or body. Ritlecitinib is a medicine taken as a pill every day, by mouth, that is approved for the treatment of severe AA. It blocks processes that are known to play a role in causing hair loss in patients with AA.

What were the results of the study?

Adults and adolescents (12 years and older) took part in the ALLEGRO-2b/3 study. They either took ritlecitinib for 48 weeks or took a placebo (a pill with no medicine) for 24 weeks. Participants taking placebo later switched to taking ritlecitinib for 24 weeks. The study showed that participants taking ritlecitinib had more hair regrowth on their scalp after 24 weeks than those taking the placebo. Hair regrowth was also seen on the eyebrows and eyelashes in participants taking ritlecitinib. Hair regrowth continued to improve to week 48 with continued ritlecitinib treatment. In addition, more participants taking ritlecitinib reported that their AA had 'moderately' or 'greatly' improved after 24 weeks than those taking the placebo. Similar numbers of participants taking ritlecitinib or placebo had side effects after 24 weeks. Most side effects were mild or moderate.

What do the results of the study mean?

Ritlecitinib was an effective and well-tolerated treatment over 48 weeks for people with AA. Clinical Trial Registration: NCT03732807 (phase 2b/3 ALLEGRO study).

Background

Alopecia areata is characterised by non-scarring loss of scalp, face, or body hair. We investigated the efficacy and safety of ritlecitinib, an oral, selective dual JAK3/TEC family kinase inhibitor, in patients with alopecia areata.

Methods

In this randomised, double-blind, multicentre, phase 2b-3 trial done at 118 sites in 18 countries, patients aged 12 years and older with alopecia areata and at least 50% scalp hair loss were randomly assigned to oral ritlecitinib or placebo once-daily for 24 weeks, with or without a 4-week loading dose (50 mg, 30 mg, 10 mg, 200 mg loading dose followed by 50 mg, or 200 mg loading dose followed by 30 mg), followed by a 24-week extension period during which ritlecitinib groups continued their assigned doses and patients initially assigned to placebo switched to ritlecitinib 50 mg or 200 mg loading dose followed by 50 mg. Randomisation was done by use of an interactive response system and was stratified by baseline disease severity and age. The sponsor, patients, and investigators were masked to treatment, and all patients received the same number of tablets to maintain masking. The primary endpoint was Severity of Alopecia Tool (SALT) score 20 or less at week 24. The primary endpoint was assessed in all assigned patients, regardless of whether they received treatment. This study was registered with ClinicalTrials.gov, NCT03732807.

Findings

Between Dec 3, 2018, and June 24, 2021, 1097 patients were screened and 718 were randomly assigned to receive ritlecitinib 200 mg + 50 mg (n=132), 200 mg + 30 mg (n=130), 50 mg (n=130), 30 mg (n=132), 10 mg (n=63), placebo to 50 mg (n=66), or placebo to 200 mg + 50 mg (n=65). 446 (62%) of 718 patients were female and 272 (38%) were male. 488 (68%) were White, 186 (26%) were Asian, and 27 (4%) were Black or African American. Of 718 patients randomly assigned, 104 patients discontinued treatment (34 withdrew, 19 adverse events [AEs], 12 physician decision, 12 lack of efficacy, 13 lost to follow up, five rolled over to long-term study transfer, four pregnancies, two protocol deviations, one declined to attend follow-up due to COVID-19, one attended last visit very late due to COVID-19, and one non-compliance). At week 24, 38 (31%) of 124 patients in the ritlecitinib 200 mg + 50 mg group, 27 (22%) of 121 patients in the 200 mg + 30 mg group, 29 (23%) of 124 patients in the 50 mg group, 17 (14%) of 119 patients in the 30 mg group, and two (2%) of 130 patients in the placebo group had a response based on SALT score 20 or less. The difference in response rate based on SALT score 20 or less between the placebo and the ritlecitinib 200 mg + 50 mg group was 29·1% (95% CI 21·2-37·9; p<0·0001), 20·8% (13·7-29·2; p<0·0001) for the 200 mg + 30 mg group, 21·9% (14·7-30·2; p<0·0001) for the 50 mg group, and 12·8% (6·7-20·4; p=0·0002) for the 30 mg group. Up to week 48 and including the follow-up period, AEs had been reported in 108 (82%) of 131 patients in the ritlecitinib 200 mg + 50 mg group, 105 (81%) of 129 patients in the 200 mg + 30 mg group, 110 (85%) of 130 patients in the 50 mg group, 106 (80%) of 132 patients in the 30 mg group, 47 (76%) of 62 patients in the 10 mg group, 54 (83%) of 65 patients placebo to ritlecitinib 200 mg + 50 mg in the extension period, and 57 (86%) of 66 patients in the placebo to 50 mg group. The incidence of each AE was similar between groups, and there were no deaths.

Interpretation

Ritlecitinib was effective and well tolerated in patients aged 12 years and older with alopecia areata. Ritlecitinib might be a suitable treatment option for alopecia areata in patients who are candidates for systemic therapy.

Funding

Pfizer.