Positive topline results were announced from a phase 3 study evaluating the efficacy and safety of CTP-543 in adults with moderate to severe alopecia areata.

CTP-543 is an investigational oral selective inhibitor of Janus kinase 1 (JAK1) and JAK2. The randomized, double-blind, placebo-controlled THRIVE-AA1 trial (ClinicalTrials.gov Identifier: NCT04518995) included 706 adults aged 18 to 65 years with moderate to severe alopecia areata who had at least 50% scalp hair loss, as measured by Severity of Alopecia Tool (SALT) score. Patients were randomly assigned to receive CTP-543 8mg or 12mg orally twice daily or placebo for 24 weeks. 

The primary endpoint was the percentage of patients achieving an absolute SALT score of 20 or less at week 24. SALT is an assessment of scalp hair loss with scores ranging from 0 (no scalp hair loss) to 100 (complete scalp hair loss). The average baseline SALT score was approximately 85.9 for all patients.

Results showed that 41.5% and 29.6% of patients treated with CTP-543 8mg and 12mg, respectively, achieved a SALT score of 20 or less, compared with 0.8% of patients who received placebo (treatment difference for both dose groups: P <.0001).

Additionally, both doses were associated with statistically significant improvements in key secondary endpoints, including the percentage of responders on a Hair Satisfaction Patient Reported Outcome scale at week 24 and the percentage of patients achieving absolute SALT scores of 20 or less at weeks 8, 12, 16, and 20.

The most common adverse reactions reported in the CTP-543 dose groups were headache, acne, upper respiratory infection, increased creatine kinase levels, COVID-19 infection and nasopharyngitis.

“With these compelling phase 3 data, we believe that CTP-543 has the potential to be a best-in-class treatment for patients with alopecia areata, a disease that has long been ignored,” said James V. Cassella, PhD, Chief Development Officer of Concert Pharmaceuticals.

CTP-543 is also being evaluated in adults with moderate to severe alopecia areata in a second phase 3 trial, THRIVE-AA2 (ClinicalTrials.gov Identifier: NCT04797650); topline data from this study are expected in the third quarter of 2022.


Concert Pharmaceuticals reports positive topline results for first CTP-543 phase 3 clinical trial in alopecia areata. News release. Concert Pharmaceuticals, Inc. Accessed May 23, 2022. https://www.businesswire.com/news/home/20220523005329/en/Concert-Pharmaceuticals-Reports-Positive-Topline-Results-for-First-CTP-543-Phase-3-Clinical-Trial-in-Alopecia-Areata