Study to Evaluate the Safety and Efficacy of Tapinarof in Adults With Palmoplantar Keratoderma

The purpose of this study is to assess adults with palmoplantar keratoderma (thickening skin layer on palms and soles) who are treated with the study drug, tapinarof. This is a naturally occuring compound used for the treatment of psoriasis. This study is being done to find out how well and safe this drug is for stopping or treating keratoderma. This study aims to investigate the positive impacts of daily topical Tapinarof use in the improvement of Keratoderma. Clinical efficacy and safety profile of prescribing Tapinarof for this condition will be evaluated.

This study aims to assess the benefits of the treatment. Should the treatment demonstrate benefits (as defined by the primary outcome measure) without any observed serious adverse events (SAEs), further clinical trials would be justified. If at least 2 out of 6 subjects benefits from the treatment (as defined by our primary outcome measure) and there are no SAEs, future clinical trials would be warranted. This initial data will determine whether it is worthwhile to proceed with a phase 2 trial, that will be both blinded and well-controlled.

The study is designed to gather preliminary experiences that can be used to design subsequent, well-controlled studies that are appropriately powered for statistical analysis. Currently, there is not enough experience with this medication in treating this specific condition, which is necessary to design successful randomized controlled trials (RCTs) for regulatory approval by the FDA. In dermatology, conducting studies in this manner is standard practice.

Eligibility Criteria:
Inclusion Criteria:

* Ability to discern and provide written informed consent and voluntarily adhere to all of the protocol requirements
* Male or female subjects in their adult years (≥ 18 years of age), inclusive, from the time of providing written subject-investigator agreement.
* Confirmed clinical diagnosis of palmoplantar keratoderma.

Exclusion Criteria:

* Treatment with any of the following medications and therapies during the duration of the study\*:

  * Topical corticosteroids
  * Keratolytic agents (eg, 6% salicylic acid, 70% propylene glycol, 30% water)
  * Topical retinoids
  * Topical vitamin D ointment (calcipotriol)
  * Oral retinoids (acitretin)

    * If on any of these then a washout period of at least 2 weeks will be enforced before the study begins. This washout period is meant to ensure that any effects or residues from previous treatments are minimized before starting the study.
* Prior exposure to Tapinarof treatment
* Known history or suspicion of hypersensitivity reactions, or contraindications to any or all components of the drug or drugs of similar properties.
* Currently participating in another clinical study for the same purpose.
* Potential or confirmed pregnancy: Individuals who are currently pregnant or have confirmed pregnancy at the time of screening will be excluded from participation in the study. This criterion aims to ensure the safety of participants and adhere to ethical considerations regarding the potential risks associated with the study interventions during pregnancy.
* Any other factors specifically not listed above but deemed patient unsuitable by the discretion of the investigators.