Efficacy of Abrocitinib for Reducing Pruritus in Adults With Prurigo Nodularis and Chronic Pruritus of Unknown Origin

The primary objective is to assess the efficacy, safety, and tolerability of Abrocitinib for the treatment of Prurigo Nodularis (PN) or Chronic Pruritus of Unknown Origin (CPUO) in patients experiencing moderate to severe pruritus.

This is a trial to assess the efficacy of Abrocitinib as a therapeutic for Prurigo Nodularis (PN) and Chronic Pruritus of Unknown Origin (CPUO). The study will consist of a 4-week Screening period, a 12-week treatment period and then a 4-week follow up period. The arms will run in parallel and patients will take 200 mg oral Abrocitinib daily for the duration of the 12-week treatment period.

Eligibility Criteria:
Inclusion Criteria:

* Males or female participants between ages 18-80 years at time of signing informed consent
* A clinical diagnosis of prurigo nodularis, defined by the presence of at least 10 pruritic nodules on at least 2 different anatomic locations (with each arm, leg, and anterior and posterior trunk considered distinct anatomic locations)

OR

* Subject has ongoing chronic pruritus of unknown origin, which must be present on multiple segments on the body. CPUO patients must not have known dermatologic or systemic conditions, that in the opinion of the investigator, are the cause of patient's pruritus
* Subject has moderate to severe pruritus, defined as average peak pruritus numeric rating scale - (PP-NRS) \> 7 (range 0-10, higher score indicating greater degree of pruritus severity) in the 7 days prior to the Screening Visit.
* Female participants are eligible for the study if they are not pregnant, planning to become pregnant or breastfeeding during the study or not a woman of child bearing potential (WOCBP)

Exclusion Criteria:

* Infected with hepatitis B or hepatitis C viruses.
* Infected with Herpes Simplex or Herpes zoster.
* Positive HIV serology at screening,
* Evidence of active or latent or inadequately treated infection with Mycobacterium tuberculosis (TB)
* History of lymphoproliferative disease, or active primary or recurrent malignancy
* History of recurrent (≥ 2) venous thromboembolism (VTE) or (DVT/PE) - deep vein thrombosis and pulmonary embolism
* Untreated thyroid, adrenal, or pituitary disease or nodules, or history of thyroid malignancy
* Have received any of the following treatment regiments specified in the timeframes outlined below:

  * Within 6 months of first dose of study drug: Rituximab, any other B cell depleting therapies, or intravenous immunoglobulin (IVIg)
  * Within 12 weeks of first dose of study drug: Any studies with Janus kinase (JAK) inhibitors; Cyclophosphamide (or any other cytotoxic agent), belimumab, or anifrolumab (or another anti-interferon (IFN) therapy)
  * Within 8 weeks of first dose of study drug: Other biologics
  * Within 6 weeks: Have been vaccinated with live or attenuated live vaccine.
  * Within 4 weeks: Participation in other studies involving investigational drug(s)
  * Within 4 weeks: Use of oral immune suppressants; systemic immunosuppressive therapies, neuromodulatory therapies, Phototherapy (NB UVB) or broad band phototherapy; Regular use (more than 2 visits per week) of a tanning booth/parlor.
  * Within 1 week of first dose of study drug: Topical treatments that could affect PN; Herbal medications with unknown properties or known beneficial effects for PN.