Business Decision

The purpose of this study is to evaluate the safety and tolerability of XmAb27564 following multiple doses among participants with plaque psoriasis and atopic dermatitis.

This is a phase 1b, randomized, double-blind, placebo-controlled, multiple ascending dose (MAD) study of XmAb27564. It is planned to enroll approximately 48 adult patients with mild-to-severe plaque psoriasis and 80 adult patients with moderate-to-severe atopic dermatitis. All patients will receive a total of 4 doses of study drug or placebo, administered subcutaneously every 2 weeks. A one year, open-label extension is available to qualifying patients.

Inclusion Criteria:

The main inclusion and exclusion criteria include, but are not limited to, the following:

• Have active mild-to-severe plaque psoriasis or moderate-to-severe atopic dermatitis according to study-specific criteria
• Weight between 40 to 150 kg, inclusive
• No topical treatments for psoriasis or atopic dermatitis for 2 weeks before randomization
• No phototherapy for psoriasis for 4 weeks before randomization
• Washout of oral treatments for psoriasis or atopic dermatitis for 4 weeks before randomization
• Washout of biologic treatments for psoriasis or atopic dermatitis for 12 weeks before randomization
• Stated willingness to comply with all study procedures (including skin biopsies) and availability for the duration of the study

Exclusion Criteria:

• Patients with a history of active asthma within 5 years of screening, except those that have well controlled asthma symptoms at screening visit.
• Patients who have had any prior investigational treatment with IL-2 therapies