15 patients with PRP will be treated with ixekizumab for 24 weeks to determine safety and efficacy. Participants are required to travel to Portland, OR only for the first visit and week-24 visit. 5 visits in between these times and one follow up visit may be performed by secure videoconferencing.

Pityriasis rubra pilaris (PRP) is a rare and poorly understood severe inflammatory skin disease characterized by widespread (often full-body) redness and flaking of the skin, painful thickening and cracking of the palms and soles, hair loss, crumbling nails, and severe skin itching and burning.

There is no FDA-approved therapy for this rare disease and the commonly used medications do not work for many patients. There is some evidence that IL-17 may be too high in the skin of PRP patients. Ixekizumab is an injectable medication that blocks IL-17 and is FDA-approved for psoriasis.

Inclusion Criteria:

• Diagnosis of PRP by clinical assessment and biopsy.
• Male subject age 18-99.
• Female subject age 18-99; either of non-childbearing potential or of childbearing potential who test negative for pregnancy and agree to use a reliable method of birth control or remain abstinent during the study and for at least 12 weeks following the last dose of ixekizumab.
• PASI score of 10 or greater at baseline.
• Are a candidate for phototherapy and/or systemic therapy.
• Willingness to travel to OHSU for all study visits, OR living >30 miles from OHSU and willing/able to participate in remote videoconferencing visits with access to a computer with internet capabilities and webcam.
• Have given written informed consent approved by the OHSU Investigational Review Board.

Exclusion Criteria:

• Known malignancy or lymphoproliferative disease (except treated basal cell skin cancer, treated squamous cell skin cancer, or treated cervical carcinoma in situ) for at least 5 years.
• Active, untreated, acute or chronic infection (such as untreated tuberculosis), or immunocompromised to an extent that such that participation in the study would pose an unacceptable risk to the subject. (Treated infections such as latent tuberculosis after completion of the appropriate therapy are not excluded.)
• Positive for human immunodeficiency virus, hepatitis B virus, or hepatitis C virus.
• Previous treatment with any agent that targets interleukins 17 specifically.
• Systemic treatment or phototherapy for PRP within the past 4 weeks or 5 half-lives prior to baseline, whichever is longer. For biologic therapies, the specific washout periods used will be: etanercept <28 days; infliximab, adalimumab, or alefacept <60 days; golimumab <90 days; ustekinumab <8 months; rituximab or efalizumab <12 months.
• Have a known allergy or hypersensitivity to any biologic therapy that would pose an unacceptable risk to the subject if participating in this study.
• Have a live vaccine within 12 weeks prior to baseline or intend to have a live vaccine during the course of study.
• Had any major surgery within 8 weeks prior to baseline or will require major surgery during the study that, in the opinion of the investigator, would pose an unacceptable risk to the subject.
• Presence of significant uncontrolled cerebrovascular, respiratory, hepatic, renal, gastrointestinal, endocrine, hematologic, neurologic, or neuropsychiatric disorders, or abnormal laboratory screening values that, in the opinion of the investigator, pose an unacceptable risk to the subject if participating in the study or of interfering with the interpretation of the data.
• Presence of inflammatory bowel disease
• Have clinical laboratory test results at screening that are outside the normal reference range of the population and are considered clinically significant, or have any of the following specific abnormalities: Neutrophil count <1500 cells/µL, lymphocyte count <500 cells/µL, platelet count <100,000 cells/µL, AST or ALT > 2.5 times the upper limit of normal, hemoglobin <8.5 g/dL for male subjects and <8.0 g/dL for female subjects, serum creatinine >2.0 mg/dL.
• Women who are lactating or breastfeeding.
• Have any other condition that precludes the subject from following and completing the protocol, in the opinion of the investigator.
• Are investigator site personnel directly affiliated with this study and/or their immediate families (spouse, parent, child, or sibling).

Are currently enrolled in, or discontinued from a clinical trial involving an investigational product or non-approved use of a drug or device within the last 4 weeks or a period of at least 5 half-lives of the last administration of the drug, whichever is longer, or concurrently enrolled in any other type of medical research judged not to be scientifically or medically compatible with this study.

All enrolled patients at baseline

24-weeks