Safety, Tolerability and Efficacy of SNA-120 for Treatment of Pruritus and Psoriasis in Subjects Treated With Calcipotriene

All subjects are required to meet eligibility requirements and undergo a calcipotriene run-in
period (Part A) prior to qualifying and randomizing into the study to receive either SNA-120
or Placebo ointment in combination with calcipotriene ointment (Part B). Combination therapy
(SNA-120 ointment + calcipotriene ointment or Placebo ointment + calcipotriene ointment) is
to continue over an 8 week period to evaluate safety, tolerability and the efficacy of
treatment on both persistent pruritus and the visible signs and symptoms of psoriasis.

Inclusion Criteria:

- Written informed consent

- Stable psoriasis for at least 6 months prior to screening

- Chronic pruritus of the psoriasis plaques at least 6 weeks prior to screening

- At least moderate baseline overall itch associated with psoriatic plaques

- Willing and able to undergo a 4-week run-in with calcipotriene ointment dosing and
remain on this stable regimen throughout the study

- Mild or moderate psoriasis at screening and baseline

- Subject's plaques are amenable to treatment with a topical medication

- Willing and able to discontinue all other topical products to treat psoriasis and/or
itch, including topical steroids

- Willing and able to avoid prolonged exposure of the designated treatment plaques to
ultraviolet (UV) radiation (natural and artificial) for the duration of the study

- Women of childbearing potential must have a negative pregnancy test and must agree to
use highly effective methods of contraception during the study

- Men who engage in sexual activity that can result in fathering children must agree to
use highly effective forms of contraception during the study

Exclusion Criteria:

- Underlying conditions other than psoriasis that, in the opinion of the investigator,
currently cause or influence pruritus of the overall skin

- Current or past history of hypercalcemia, Vitamin D toxicity, severe renal
insufficiency, or severe hepatic disorders

- Thyroid abnormalities that, in the opinion of the investigator, are clinically
relevant and may affect assessments

- Current diagnosis of guttate, erythrodermic, exfoliative, or pustular psoriasis

- Subjects with a clinical diagnosis of bacterial infection of the skin

- Subjects who have previously failed treatment with or failed to tolerate treatment
with calcipotriene

- Known hypersensitivity to SNA-120 (pegcantratinib), calcipotriene, the study treatment
excipients, and /or polyethylene glycol (PEG), or a history of drug or other allergy
that, in the opinion of the investigator, contraindicates participation

- Currently enrolled in an investigational drug or device study or has used an
investigational drug or an investigational device treatment within 30 days or 5
half-lives of investigational drug (whichever is longer) of baseline

- Women who are pregnant or lactating, or are planning to become pregnant during the
study

- Subjects previously participating in any SNA-120 (and/or CT327 or pegcantratinib)
clinical studies