Safety, Tolerability, PK, PD and Preliminary Efficacy of ONO-4685

Inclusion Criteria

• Subjects must be willing and able to participate in the study

• A diagnosis of plaque-type psoriasis for ≥6 months.

• Plaque-type psoriasis involving ≥3% of body surface area (BSA) (Parts B and C).

• Willing to provide skin biopsies (Parts B and C).

• Subjects in good health, as judged by medical history, medical examination, vital signs, ECG and clinical laboratory tests.

• Subjects willing to comply with the contraception and sperm and ova donation requirements of the protocol.

Exclusion Criteria

• Subjects with any clinically significant abnormality in screening tests.

• Guttate, erythrodermic or pustular psoriasis as sole or predominant form of the psoriasis, or other skin condition (eg eczema).

• Presence or history of alcohol or drugs abuse.

• Heavy smokers (more than 20 cigarettes or use more than ½ ounce (12.5 grams) of tobacco each day).

• Subjects have had any 'live' vaccines (excluding COVID-19 vaccine) during the 3 months before the first dose of study medicine.

• Subjects have had a first COVID-19 vaccine within 6 weeks or second and booster COVID-19 vaccinations within 2 weeks before the first dose of study medicine.

• Subjects have had any clinically significant disease or infection, including tuberculosis.

• Presence or history of malignancy (cancer) including lymphoproliferative disorders.

• Subject is pregnant, lactating, or breastfeeding.

• Subjects have received treatment with biologics in the last 3 months, immunosuppressant medicine or prescription medicine for psoriasis within 4 weeks before admission to the ward; have used phototherapy from 2 weeks before admission to the ward; have used highly potent or potent topical steroids within 2 weeks before admission to the ward.

• Subjects have used topical corticosteroids or Vitamin D analogues within 7 days before admission to the ward (Parts B and C).