This study examines the effect of IL-23 blockade with Tildrakizumab on the immune cells of psoriatic skin lesions.

This is a one-arm, open-label study to examine the effect of Tildrakizumab. Tildrakizumab is a FDA-approved medication for the treatment of cutaneous psoriasis. This study will examine how Tildrakizumab affects immune cells within psoriatic skin lesions. Fifteen subjects with moderate to severe psoriasis will be enrolled. Biopsy samples will be collected and undergo molecular profiling to correlate profiles with and to predict Tildrakizumab treatment response.

Inclusion Criteria:

• Male or female ≥18 years of age at clinic visit.
• Documentation of moderate-severe psoriasis or atypical psoriasis.
• Written informed consent (and assent when applicable) obtained from subject or subject's legal representative and ability for subject to comply with the requirements of the study.

Exclusion Criteria:

• Presence of a condition or abnormality that in the opinion of the Investigator would compromise the safety of the patient or the quality of the data
• Tuberculosis, active serious infection, active systemic malignancy,
• Received a systemic medication for psoriasis within 3 months of study screening

3 months