Study of Modzatinib (ATI-2138) in Adult Participants With Biopsy-proven Forms of Lichen Planus Not Adequately Controlled With Topical Therapies (ALPHA)

Key Inclusion Criteria:

• Participants must have biopsy-confirmed OLP, CLP, or LPP eligible for systemic therapy and a history of inadequate response to topical corticosteroids (TCS) of high or ultra-high potency (based on the World Health Organization [WHO] definition) for at least 4 weeks in the opinion of the Investigator.

Specific criteria for each subtype below:

• OLP: OLP IGA of ≥ 3 (moderate or severe) and either Baseline LP-related Pain or Burning Sensation NRS ≥ 3.
• CLP: CLP IGA ≥3 (moderate or severe) and Baseline LP-related Itch NRS ≥ 3.
• LPP: LPP IGA ≥ 3 (moderate or severe) and either Baseline LP-related Itch or Burning Sensation NRS ≥ 3.
• If using any of the permitted treatments (that is, topical treatments on the affected areas, oral pain medications, and systemic antihistamines), the dose and frequency should remain stable for at least 2 weeks prior to randomization (Day 1) and until Week 16 (OLP and CLP cohorts) or Week 24 (LPP cohort).
• Participant has a stable disease for at least 4 weeks prior to screening visit based on Investigator judgement.
• Participant must be willing and able to comply with all study procedures and must be available for the duration of the study.

Key Exclusion Criteria:

• Clinical history suspicious for and/or biopsy consistent with lichenoid drug eruption.
• History or diagnosed LP other than OLP, CLP, or LPP (for example, lichen planus pigmentosus, paraneoplastic mucosal lichen planus, hypertrophic lichen planus, as well as actinic, inverse, linear, or bullous variants).
• Participants with dysplastic changes in oral biopsy results.
• Participant has any clinically significant medical condition, other skin conditions (including skin, scalp or mucosa infections), or physical/laboratory/electrocardiogram (ECG)/vital signs abnormality that would, in the opinion of the investigator, put the participant at undue risk or interfere with the study assessments.
• Participant has any condition that could interfere with drug absorption including, but not limited to, short bowel syndrome, gastric bypass surgery (including sleeve gastrectomy). Participants with a history of gastric banding/segmentation are not to be excluded.
• Participant has a known or suspected allergy to modzatinib or any component of the investigational product.
• Participant is a female who is breastfeeding, pregnant, or who is planning to become pregnant during the study.

Note: Other protocol-defined inclusion and exclusion criteria may apply.