Psoriasis is an inflammatory autoimmune disease that might be controlled by a cathepsin S inhibitor like VBY-891.

Refer to Brief Summary

Inclusion Criteria:

• Male or female, 18-60 years old
• Screening body mass index between 18-32 kg/m2
• Good health, no clinically significant findings in medical history, 12-lead ECG, & vital signs;
• Clinical lab evaluations (Chem panel [fasted at least 8 hrs], CBC, HbA1c & UA in reference range for test lab (unless deemed not clinically significant);
• Negative test for drugs of abuse at Screening & at Check-in (includes alcohol);
• Negative hepatitis, HIV & TB screens;
• Females non-pregnant, non-lactating, & either postmenopausal for at least 1 year, surgically sterile for at least 90 days prior to Check-in, or agree to use from the time of consent until 90 days after Study Completion an effective form of contraception. For all females, a pregnancy test result must be negative at Screening & Check-in.
• Males will be sterile or agree to use from Check-in until 90 days following discharge an effective method of contraception.
• Able to comprehend & willing to sign Informed Consent Form

Exclusion Criteria:

• Females pregnant or nursing, or childbearing potential but unwilling to use contraception.
• History of renal or hepatic impairment; stomach or intestinal surgery or resection, malabsorption syndrome, cholecystectomy, or gastro-intestinal dysfunction that would alter absorption &/or excretion of orally administered drugs (appendectomy or hernia repair allowed);
• Anemia (hemoglobin <11.5 g/dL for females; < 13 g/dL for males) or blood donation within 8 weeks of Check-in;
• Plasma donation within 4 weeks of Check-in;
• History of alcoholism or drug addiction within 6 months to Check-in;
• Use of drugs of abuse or prescription drugs for recreational use 6 months prior to Check-in;
• Use of any tobacco-containing or nicotine-containing products 6 months prior to Check-in & during study;
• Participation in another drug trial 30 days of Check-in (within 8 weeks if previous investigational drug has immunomodulatory effects, other than cathepsin S inhibition);
• History or clinical manifestations of metabolic, hepatic, renal, hematological, pulmonary, cardiovascular, gastrointestinal, urological, neurological, or psychiatric disorders
• History of hypersensitivity or allergies to any drug compound
• History or presence of abnormal ECG
• Laboratory abnormality deemed clinically significant;
• Use of or inability to discontinue any prescription medications/products 14 days prior to Check-in & during study;
• Use of certain over-the-counter, non-prescription preparations are permitted up to 3 days before first dose;
• Use of alcohol-containing, grapefruit-containing, star fruit containing foods or beverages or "energy drinks" 72 hours to Check-in & during study;
• Poor peripheral venous access;
• Receipt of blood products 6 months to Check-in
• Subjects with history of Gilbert's Syndrome;
• Strenuous activities 48 hours to Check-in
• Illness 5 days to drug administration
• Any acute or chronic condition