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Study of ritlecitinib tosilate for hair regrowth in adults and adolescents (12 years and older) with moderate alopecia areata

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What is this trial about?

A plain-language summary of the goals, design and what participants do

The study focuses on people 12 years of age and older who have moderate alopecia areata, a condition that causes patchy hair loss on the scalp. The treatment being tested is an oral capsule called ritlecitinib, which is taken once daily at either a 50 mg or 100 mg dose. A comparison pill that contains no active medicine, known as a placebo, is also used in the trial.

The purpose of the study is to see whether ritlecitinib helps hair grow back better than the placebo. Participants are randomly assigned to receive either ritlecitinib or the placebo, and neither the participants nor the study staff know which one is being given, keeping the study double‑blind.

After an initial screening visit, participants take the assigned study medication for about 24 weeks, with regular check‑ups to monitor safety and to measure hair growth using a scoring system called the SALT score, which rates the amount of scalp hair loss. The study includes several visits during the treatment period to collect information and ensure the medication is well tolerated.

The research process

The trial runs in 7 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Baseline Visit and Randomization

    On the first day you attend a clinic visit where the study staff confirm eligibility and assign you to one of the study groups. You will receive either a ritlecitinib capsule (50 mg or 100 mg) or a matching placebo capsule that looks the same. The capsule is taken by mouth (oral). The treatment period is planned for 24 weeks.

  2. Step 2

    Daily Medication

    You take one capsule each day, preferably at the same time each morning, with a glass of water. Do not skip doses. The capsule you received contains either 50 mg or 100 mg of ritlecitinib, or no active drug if you were assigned to the placebo group.

  3. Step 3

    Week 4 Safety Check‑in

    Four weeks after starting the medication you return to the clinic for a brief safety check. The staff will ask about any side effects and may take a small blood sample. The dose of the capsule remains the same.

  4. Step 4

    Week 8 Hair‑Growth Assessment

    At eight weeks you have a clinic visit where the doctor measures hair regrowth using the SALT score (Severity of Alopecia Tool). This score helps determine how much of the scalp area has hair. You continue taking the same daily capsule.

  5. Step 5

    Week 12 Hair‑Growth Assessment

    Twelve weeks after the start you return for another SALT score measurement and safety review. The medication dose does not change.

  6. Step 6

    Week 18 Hair‑Growth Assessment

    At eighteen weeks you attend a further clinic visit for the same assessments of hair growth and safety. The daily capsule continues as before.

  7. Step 7

    Week 24 Final Assessment and End of Treatment

    Twenty‑four weeks after the first dose you have the final clinic visit. The doctor records the final SALT score and asks you to rate your overall improvement. After this visit you stop taking the study capsule. The results from this visit are used to evaluate the effectiveness of ritlecitinib compared with placebo.

Who can join the trial?

6 criteria

  • You must be at least 12 years old.
  • You need a doctor‑confirmed diagnosis of alopecia areata (AA), an autoimmune condition that causes patches of hair loss.
  • You must have lost between 20% and 50% of the hair on your scalp.
  • The current period of hair loss must have lasted at least 6 months but no more than 10 years.
  • The hair loss must be caused by alopecia areata only; other reasons for hair loss are not allowed.
  • Both men and women are eligible to take part in the study.

Who cannot join the trial?

4 criteria

  • You cannot join if you have a history of malignancies (cancers), except if you had a skin cancer called basal cell or squamous cell cancer that was completely removed and did not spread, or a very early form of cervical cancer called cervical carcinoma in situ that was properly treated.
  • You cannot join if you have ever taken a medication known as a Janus kinase inhibitor (a type of drug that blocks certain enzymes in the body).
  • You cannot join if the cause of your hair loss is something other than alopecia areata.
  • If you are a teenager, you cannot join unless you can show that you are immune to the varicella zoster virus (the virus that causes chickenpox and shingles) either through vaccination or a blood test called serological testing.
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Investigated drugs

Ritlecitinib is an oral capsule taken by mouth. It works by blocking a specific enzyme that plays a role in the immune system. In people with alopecia areata, the immune system can mistakenly attack hair follicles, stopping hair from growing. By inhibiting this enzyme, ritlecitinib may reduce the immune attack and allow hair on the scalp to start growing again. In the study, participants took the medication each day, and researchers measured how much new hair grew compared with those who received a placebo.

What is already known about the treatment

Ritlecitinib tosylate - It is taken by mouth as a hard capsule (available in 50 mg and 100 mg strengths). Ritlecitinib is an investigational drug that has been studied in several Phase 2 and Phase 3 trials and is not yet approved for routine medical use. It is being tested mainly for moderate alopecia areata, a condition that causes patchy hair loss. The medicine works by blocking the activity of Janus kinase 3 (JAK3) and the related protein TEC, which reduces the immune signals that attack hair follicles; it belongs to the class of JAK inhibitors.

Investigated diseases

moderate alopecia areata - Alopecia areata is an immune‑mediated condition that causes sudden, patchy loss of scalp hair. In the moderate form, the affected area typically covers a larger portion of the scalp but does not involve the entire head. The hair loss can spread over weeks to months, and new patches may appear while existing ones persist. Without treatment, the condition may remain stable at its current extent or gradually progress to more extensive hair loss.
Trial detailsLast updated 28 Oct 2026
Age18+ yearsPhasePhase IIITrial ID2026-526355-62-00Protocol codeB7981110Estimated enrolment336 patientsSponsorPfizer Inc.

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