By: Anjali Thykattil, PharmD Candidate c/o 2025 and Isabelle Lim, PharmD Candidate c/o 2024

Effective June 23rd, 2023, the United States Food and Drug Administration (FDA) approved Pfizer’s LITFULO™ (ritlecitinib) for the treatment of severe alopecia areata in adults and adolescents above the age of 12 years. While ritlecitinib is the second FDA approved treatment for alopecia areata, it is the first FDA approved treatment for alopecia areata in adolescents.¹ Ritlecitinib oral therapy is recommended at a once daily dose of 50 mg.² It is not recommended to be used in combination with other Janus kinase (JAK) inhibitors, biologic immunomodulators, cyclosporine, or other potent immunosuppressants.

About Alopecia Areata

Alopecia areata is a T cell mediated autoimmune disease characterized by non-scarring hair loss. The disease may progress to total loss of scalp hair (alopecia totalis) or total loss of hair on the body (alopecia universalis).³ While the etiology of alopecia areata is unclear, it is suspected to be related to genetic disposition, oxidative stress, and psychologic stress. Unfortunately, alopecia areata has an unpredictable prognosis. It is typical for patients to have periods of remission followed by periods of relapses.⁴ It is worth noting that the hair loss experienced by patients can be psychologically distressing and can have a substantial effect on quality of life.

Current Treatment Guidelines

Current treatment options for alopecia areata include topical and/or systemic agents and are individualized for patients based on their symptoms. Off-label treatment with corticosteroids or other immunosuppressants is a common choice. Baricitinib is an oral inhibitor of JAK1 and 2.⁵ It was approved by the FDA in June 2022 for the treatment of severe alopecia areata in adults. Standard dosing for baricitinib is a starting dose of 2 mg once daily, which may then be increased to 4 mg once daily if an adequate response is not seen. Additionally, those with severe hair loss all over their body may begin the medication at the 4 mg dose. Once improvement is seen at the 4 mg dose, patients may be lowered to the 2 mg dose for consistent use.⁶ Prior to the approval of ritlecitinib, baricitinib was the only approved treatment for the disease.

Ritlecitinib, Clinical Trials, and Relevancy

Ritlecitinib is an orally administered kinase inhibitor. The drug irreversibly inhibits JAK3 and the tyrosine kinase expressed in hepatocellular carcinoma (TEC) kinase family. As previously mentioned, the pathophysiologic cause of alopecia areata is uncertain. However, it is known that there is dysregulation of the cytolytic activity of T cells. Ritlecitinib allows for selective dual inhibition of JAK3 and TEC which may block signaling of various cytokines and the cytolytic activity T cells. Additionally, in patients with alopecia areata, ritlecitinib treatment was associated with dose-dependent early reductions in absolute lymphocyte count (ALC), CD3+, CD4+, and CD8+ T cells, and natural killer (NK) cells.⁷

Ritlecitinib’s efficacy in the treatment of alopecia areata was assessed in ALLEGRO-2b/3.⁸ ALLEGRO-2b/3 is a randomized, double-blind, multinational, phase 2b/3 trial. Patients in this trial were adults (18 years or older) and adolescents (aged 12 to 17 years old) with alopecia areata who experienced greater than 50% hair loss of the scalp. Patients with alopecia totalis and alopecia universalis were also included. Exclusion criteria for this trial included any other causes of alopecia and previous use of any JAK inhibitor.⁸ To assess improvement, the Severity of Alopecia Tool (SALT) was used. Scores range from 0 (no scalp hair loss) to 100 (total scalp hair loss).⁸ Patients were randomized to receive ritlecitinib 200 mg for 4 weeks followed by 50 mg (n = 132), ritlecitinib 200 mg for 4 weeks followed by 30 mg (n = 130), ritlecitinib 50 mg (n = 130), ritlecitinib 30 mg (n = 132), ritlecitinib 10 mg (n = 63), placebo for 24 weeks followed by ritlecitinib 200 mg for 4 weeks then 50 mg (n = 65) or placebo for 24 weeks followed by ritlecitinib 50 mg (n = 66). Medication was administered orally, once daily, for 24 weeks.⁸ At 24 weeks, the proportions of patients achieving the primary endpoint of a SALT score of greater than or equal to 20 were 31%, 22%, 23%, 14%, and 2% in the ritlecitinib 200 + 50 mg, 200 + 30 mg, 50 mg, 30 mg and 10 mg groups, respectively, compared with 2% in the combined placebo group. The difference between ritlecitinib and placebo was significant (p ≤ 0.0002) in all but the 10 mg group which was included for pharmacokinetic, dose-response, and safety assessments only.⁸

In a longer term, ongoing phase 3 clinical trial, ALLEGRO-LT, ritlecitinib was further studied on its sustained clinical efficacy in patients with alopecia areata.⁷ This trial includes both rollover patients from ALLEGRO-2a and ALLEGRO-2b/3 and de novo patients who had not received treatment in other ALLEGRO trials. Eligible patients were aged ≥ 12 years with ≥ 25% scalp hair loss due to alopecia areata, no evidence of terminal hair regrowth within 6 months and maximum duration of current episode of hair loss ≤ 10 years.⁷ All the patients were given ritlecitinib 200 mg once daily for 4 weeks followed by 50 mg once daily. In an early analysis of de novo patients (n = 447), 62% of patients were categorized as responders; 44% were early responders (SALT score of greater than 20 at weeks 24, 48 and 96), 11% were middle responders (SALT score of greater than 20 by week 48 and at week 96) and 6% were late responders (SALT score of greater than 20 by week 96). Greater than 84% of patients sustained their clinical response through week 96.⁷

Conclusion

Ritlecitinib has exhibited sustained long-term efficacy in patients with alopecia areata, as described in the ALLEGRO-2b/3 and ALLEGRO-LT trials. Often, patients with the disease experience social isolation due to the hair loss which then causes sadness and stress. This mental anguish may then cause further hair loss to occur. Alopecia areata is a psychologically debilitating disease for patients who experience it, especially for adolescents. Currently, the only treatment option for adolescents is the off-label use of corticosteroids. Ultimately, the approval of ritlecitinib is a major step in providing a treatment plan for adolescents with alopecia areata.

References

1. Pfizer Inc. FDA Approves Pfizer’s LITFULO™ (Ritlecitinib) for Adults and Adolescents with Severe Alopecia Areata. Pfizer. https://www.pfizer.com/news/press-release/press-release-detail/fda-approves-pfizers-litfulotm-ritlecitinib-adults-and. Published 06/23/2023.
2. Litfulo (Ritlecitinib) [package insert]. New York, NY; Pfizer Inc.; Revised 06/01/2023.
3. Simakou T, Butcher JP, Reid S, Henriquez FL. Alopecia areata: A multifactorial autoimmune condition. J Autoimmun. 2019;98:74-85. doi:10.1016/j.jaut.2018.12.001
4. Lintzeri DA, Constantinou A, Hillmann K, Ghoreschi K, Vogt A, Blume-Peytavi U. Alopecia areata – Current understanding and management. J Dtsch Dermatol Ges. 2022;20(1):59-90. doi:10.1111/ddg.14689
5. Olumiant (baricitinib) [package insert]. Indianapolis, Indiana; Eli Lilly and Company; Revised 05/01/2022.
6. King B, Ohyama M, Kwon O, et al. Two Phase 3 Trials of Baricitinib for Alopecia Areata. N Engl J Med. 2022;386(18):1687-1699. doi:10.1056/NEJMoa2110343
7. Blair HA. Ritlecitinib: First Approval. Drugs. 2023;83(14):1315-1321. doi:10.1007/s40265-023-01928-y
8. Hordinsky M, Hebert AA, Gooderham M, et al. Efficacy and safety of ritlecitinib in adolescents with alopecia areata: Results from the ALLEGRO phase 2b/3 randomized, double-blind, placebo-controlled trial. Pediatr Dermatol. 2023;40(6):1003-1009. doi:10.1111/pde.15378

Published by Rho Chi Post