A Study to Learn How Safe ACT-777991 is and How Well it Works in Adults With Non-segmental Vitiligo

A Phase 2a, Proof of Concept, Multicenter, Double Blind, Randomized, Placebo Controlled, Parallel Group Trial to Assess the Efficacy and Safety of ACT-777991 in Adults With Non-segmental Vitiligo

The purpose of this clinical trial is to learn how well ACT-777991 works, how safe it is and how well it is tolerated by adults with non-segmental vitiligo.

The main question this clinical trial aims to answer is:

• Can ACT-777991 help return color to the skin of the face of adults with non-segmental vitiligo?

Researchers will compare ACT-777991 to placebo (a look-alike inactive treatment that contains no medicine) to see if ACT-777991 works to treat non-segmental vitiligo.

Trial participants will:

• Take the trial intervention (either ACT-777991 or placebo) daily for 24 weeks.
• Visit the clinic 7 times for check-up and tests.

The trial includes three trial periods:

Following a Screening period, during which it will be checked if participants are eligible to take part, eligible participants will be randomized in a 2:1 ratio to receive either ACT-777991 or placebo for 24 weeks (Trial intervention period). On completion of treatment, participants will be followed for 30 (+7) days (Follow-up period).

Trial participation will end with a Follow-up visit (Participant Last Visit) at the end of the Follow-up period.

The maximum trial duration for an individual participant is approximately 33 weeks including a screening period of up to 28 days, a treatment period of 24 weeks, and a follow-up period of up to 37 days.

Inclusion Criteria:

• Clinical diagnosis of either active or stable non segmental vitiligo for at least 3 months prior to Screening and meet all the following criteria:

  • F-VASI score ≥ 0.3 based on BICR at Screening.
  • T-VASI score ≥ 5 based on investigator assessment at Screening and Randomization.
  • Total body surface area (BSA) involvement, including the face, ≤ 50% based on investigator assessment at Screening and Randomization.

• Participants must agree not to use therapeutic agents and procedures to treat vitiligo from Screening until Participant Last Visit.

Exclusion Criteria:

• Clinical diagnosis of other forms of vitiligo (e.g., segmental) or other hypo- or depigmentation disorders (e.g., piebaldism, leukoderma, Vogt-Koyanagi-Harada disease, malignancy-induced hypopigmentation).
• Any autoimmune disease, except adequately treated thyroid disease.
• History of systemic immunotherapy treatment, including JAK inhibitors, for any inflammatory disease in the 12 months prior to Randomization.
• History of topical JAK inhibitors for any inflammatory disease in the 6 weeks prior to Screening.
• Use of laser or light-based treatment (phototherapy), including tanning beds, in the 8 weeks prior to Screening.
• eGFR < 90 mL/min/1.73 m2, defined by the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) creatinine equation, at Screening.