A Study to Assess the Efficacy and Safety of MSTT1041A in Participants With Moderate to Severe Atopic Dermatitis

Study Overview
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Brief Summary
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This study will assess the efficacy and safety of MSTT1041A (astegolimab) in participants with moderate to severe atopic dermatitis (AD). The study consists of a screening period, a 16-week treatment period, and an 8-week follow-up period.

Official Title
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A Phase II, Randomized, Double-Blind, Placebo-Controlled Multicenter Study to Assess the Efficacy and Safety of MSTT1041A in Patients With Moderate to Severe Atopic Dermatitis

Conditions
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Atopic Dermatitis

Intervention / Treatment
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* Drug: MSTT1041A
* Drug: Placebo


Participation Criteria
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Eligibility Criteria
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Inclusion criteria Ability to comply with the study protocol Chronic AD that has been present for at least 3 years before the screening visit Documented recent history (within 6 months before the screening visit) of inadequate response to treatment with topical medications (medications or treatments applied directly to part of the body) or for whom topical treatments are otherwise medically inadvisable Exclusion criteria Prior treatment with MSTT1041A Treatment with any investigational therapy (with the exception of biologics) within 8 weeks or within 5 half-lives whichever is longer, before screening Treatment with any cell-depleting agents within 6 months before screening, or until lymphocyte count returns to normal, whichever is longer Treatment with other biologics within 3 months or 5 half-lives before screening, whichever is longer Comorbid conditions that may interfere with evaluation of investigational medicinal product History or evidence of substance abuse that would pose a risk to participant safety, interfere with the conduct of the study, have an impact on the study results, or affect the participant's ability to participate in the study History of anaphylaxis, hypersensitivity to a biologic agent, or known hypersensitivity to any component of the MSTT1041A or placebo injection Planned surgical intervention during the course of the study Pregnant or breastfeeding, or intending to become pregnant during the study Participant who is a member of the investigational team or his/her immediate family

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 75 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Quadruple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Treatment<br>Participants will receive MSTT1041A | Drug: MSTT1041A<br>* Participants will receive subcutaneous (SC) MSTT1041A<br>* Other names: astegolimab;|
| Placebo Comparator: Placebo<br>Participants will receive placebo matched to MSTT1041A | Drug: Placebo<br>* Participants will receive SC placebo<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Percent Change of Total Eczema Area and Severity Index (EASI) Score | The Eczema Area and Severity Index (EASI) is a standardized instrument to evaluate the extent and severity of atopic dermatitis. An area score comprised of the percentage of skin affected by eczema for each of 4 body regions (head/neck, trunk, upper extremities, and lower extremities) is calculated with 0 = none, 1 = 1-9%, 2 = 10-29%, 3 = 30-49%, 4 = 50-69%, 5 = 70-89%, and 6 = 90-100%. Severity is scored for each of the 4 body regions by the summation of the intensity scores for 4 signs (redness, thickness, scratching, and lichenification), with 0 = none/absent, 1 = mild, 2 = moderate, and 3 = severe. The minimum final EASI score is 0 and the maximum score is 72. | Baseline, Week 16 | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Proportion of Participants Who Achieve Investigator's Global Assessment (IGA) Response of 0 or 1 |  | Baseline, Week 16 | 
| Proportion of Participants Who Achieve >/=75% Reduction From Baseline in Eczema Area and Severity Index (EASI-75) Score |  | Baseline, Week 16 | 
| Percent Change in Pruritus as Assessed by a Numeric Rating Scale (NRS) | The Peak Pruritis Numerical Rating Scale (NRS) is a single-item patient-reported outcome (PRO) of itch severity rated on a scale of 0-10, with 0 = no itch and 10 = worst itch imaginable for the prior 24-hour period. | Baseline, Week 16 | 
| Percent Change in Body Surface Area (BSA) With Atopic Dermatitis (AD) Involvement |  | Baseline, Week 16 | 
| Percent Change in Disease Severity as Assessed by SCORing Atopic Dermatitis (SCORAD) | SCORAD is a tool used to assess the extent and severity of eczema based on three aspects of disease severity: extent, intensity, and a subjective (PRO) symptoms. A total score (0-103) is calculated, with higher scores indicating a higher extent and severity of symptoms. | Baseline, Week 16 | 
| Percentage of Participants With Adverse Events (AE) |  | Up to Week 24 | 
| Serum Concentrations of MSTT1041A |  | At pre-defined intervals from baseline up to Week 24 | 
| Incidence of Treatment-Emergent Anti-Drug Antibodies (ADAs) |  | Up to Week 24 |