Study of the Efficacy, Safety and Tolerability of Serlopitant for the Treatment of Pruritus (Itch) With Plaque Psoriasis

Inclusion Criteria:

1. Male or female, age 18-80 years at consent.

2. Diagnosis of plaque psoriasis for at least 6 months prior to randomization.

a. Presence of plaque psoriasis in any anatomic location, covering ≤ 10% BSA in total,
at the Screening and Baseline visits.

3. Pruritus of at least 4 weeks' duration prior to the initial Screening visit, and
throughout the screening period prior to randomization.

4. Subjects must be willing to discontinue use of all psoriasis therapies other than the
following, for the duration of the study: bland emollients (e.g., Cetaphil, Eucerin,
Aquaphor) on any anatomic location; coal tar shampoos, limited to use on scalp.

5. WI-NRS initial screening score consistent with severe pruritus.

6. WI-NRS scores during the 2 weeks of screening consistent with sever pruritus.

7. All female subjects who are of childbearing potential must be willing to practice
highly effective contraception (i.e., pregnancy prevention method with a failure rate
of < 1% per year) from the time of the initial Screening visit until 2 weeks after
last dose of study drug.

8. Weight ≥ 32 kg at the Screening and Baseline visits.

9. Willing and able to complete daily eDiary entries within a consistent timeframe for
the duration of the study.

1. Subjects must have ≥ 80% eDiary completion rate during the two weeks of the
screening period immediately prior to randomization.

Exclusion Criteria:

1. Prior treatment with serlopitant.

a. Prior treatment with other neurokinin-1 receptor (NK1-R) antagonists (e.g.,
aprepitant, fosaprepitant, rolapitant) is not allowed within 1 year prior to
randomization.

2. Clinical worsening of psoriasis in the opinion of the investigator (e.g., increase in
affected BSA or severity requiring use of systemic psoriasis therapies) within 12
weeks prior to randomization.

3. Predominance of non-plaque forms of psoriasis (e.g., guttate, drug-induced, pustular,
erythrodermic).

4. Presence of any concurrent medical condition that provides a clearly defined etiology
for pruritus other than psoriasis. These include but are not limited to urticaria,
atopic dermatitis or other dermatologic conditions, hepatic or renal disease,
psychogenic pruritus, drug reaction, untreated hyperthyroidism, and infection.

5. Treatment with systemic biologic therapies including but not limited to etanercept,
infliximab, adalimumab, ustekinumab, secukinumab, or ixekizumab, within 6 months or 5
half-lives (whichever is longer) prior to randomization.

6. Treatment with systemic non-biologic psoriasis therapies, including but not limited to
systemic corticosteroids, phosphodiesterase-4 inhibitors, Janus kinase inhibitors,
cyclosporine, methotrexate, retinoids, hydroxyurea, mycophenolate mofetil,
thioguanine, sirolimus, azathioprine, or fumaric acid derivatives, within 12 weeks
prior to randomization.

7. Treatment with any of the following therapies within 4 weeks prior to randomization:

a. Any topical/local psoriasis therapies other than those permitted per inclusion #4,
including but not limited to topical corticosteroids, vitamin D analogues, calcineurin
inhibitors, phosphodiesterase-4 inhibitors, Janus kinase inhibitors, non-shampoo forms
of coal tar, salicylates, retinoids, anthralin, or excimer laser.

i. Non-systemic corticosteroids that do not involve skin application (e.g., inhaled,
intranasal, or intra-articular corticosteroids) will be permitted.

b. Phototherapy, with or without psoralen. c. Use of an indoor tanning facility, or
sun exposure likely to result in sunburn.

d. Systemic therapies with recognized anti-pruritic properties including but not
limited to H1 antihistamines, doxepin, mirtazapine, gabapentin, pregabalin,
cannabinoids, and kappa opioid receptor agonists.

e. Any topical anti-pruritic therapies, including but not limited to H1
antihistamines, doxepin, capsaicin, or medicated emollients (e.g., menthol or
pramoxine).

f. Strong CYP3A4 inhibitors.

8. Treatment with any investigational therapy within 4 weeks or 5 half-lives (whichever
is longer) prior to randomization.

9. Serum creatinine, total bilirubin, alanine aminotransferase (ALT) or aspartate
aminotransferase (AST) > 2x the upper limit of normal (ULN) during screening.

10. History of malignancy within 5 years prior to randomization, with the exception of
completely treated and non-metastatic basal cell carcinoma or squamous cell carcinoma
of the skin.

11. Presence of any of the following conditions meeting DSM-5 diagnostic criteria within 3
years prior to randomization: major depressive disorder, bipolar disorder,
schizophrenia, psychotic disorder, intellectual disability, severe alcohol use
disorder, or other known psychiatric condition meeting DSM-5 diagnostic criteria which
may confound the assessment of serlopitant safety or efficacy, compromise the safety
of the subject, or interfere with the subject's ability to comply with
protocol-mandated activities.

12. Suicidal ideation within 3 years prior to randomization, or history of suicide attempt
at any time.

13. Known active hepatitis infection.

14. Known history of human immunodeficiency virus (HIV) infection.

15. Documented history of parasitic infection, including skin parasites such as scabies,
within 12 months prior to randomization.

16. History of hypersensitivity to serlopitant or any of its components.

17. Currently pregnant or breastfeeding female subject.

18. Presence of any medical condition or disability that, in the investigator's opinion,
could interfere with the assessment of serlopitant safety or efficacy, compromise the
safety of the subject, or interfere with the subject's ability to comply with
protocol-mandated activities; this includes any clinically significant screening ECG
abnormalities any may include some clinically significant screening laboratory
abnormalities.

a. Unless specifically excluded per exclusion #9, clinically significant laboratory
abnormalities at screening which are unlikely to interfere with the assessment of
safety or efficacy in this trial, compromise the safety of the subject, or interfere
with the subject's ability to comply with protocol mandated activities are permitted.

19. Planned or anticipated major surgical procedure or other activity that would interfere
with the subject's ability to comply with protocol-mandated assessments (e.g.,
extended international travel) during the subject's participation in the study.