Pharmacokinetics, Immunogenicity and Safety of Subcutaneous Dupilumab and Berahyaluronidase Alfa (ALT-B4) Coformulation (EXTENSA)

A Randomized, Open-label, Multiple-dose Phase 3 Study to Evaluate Pharmacokinetics, Immunogenicity and Safety of Subcutaneous Dupilumab and Berahyaluronidase Alfa (ALT-B4) Coformulation Compared to the Approved Subcutaneous Dupilumab Formulation in Adults and Adolescents With Moderate-to-severe Atopic Dermatitis

This is a Phase 3, open label, randomized, parallel-group, 2-arm study. The purpose of this study is to measure PK, immunogenicity, safety and, tolerability of dupilumab hyaluronidase coformulation compared with dupilumab approved formulation in male or female participants with moderate-to-severe atopic dermatitis (AD) aged ≥12 years of age. Study details as follows:

• The study duration includes screening period up to 4 weeks + treatment period of 20 weeks (± 3 days) and follow-up of 12 weeks (± 7 days).
• The number of on-site visits will be 10 and one phone contact will be scheduled (during the follow-up period).

Study Overview

• Status: Not yet recruiting
• Conditions: Dermatitis Atopic
• Intervention / Treatment: Drug: Dupilumab coformulated with berahyaluronidase alfa; Drug: Dupilumab

• Study Type: Interventional
• Enrollment (Estimated): 150
• Phase: Phase 3

Contacts and Locations

• Study Contact: Name: Trial Transparency email recommended (Toll free for US & Canada); Phone Number: option 6 800-633-1610; Email: Contact-US@sanofi.com

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 12 years and older (Child, Adult, Older Adult)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: All

Description

Inclusion Criteria:

• Participant must be ≥12 years of age at the time of signing the informed consent.

• Participants with chronic AD, (according to American Academy of Dermatology Consensus Criteria, that has been present for at least 12 months before the screening visit.

• Participants with ≥10% body surface area (BSA) of AD involvement at the screening and baseline visits.

• Participant's AD must be graded as Eczema Area and Severity Index (EASI) score ≥16 at the screening and baseline visits.

• Validated Investigator Global Assessment for Atopic Dermatitis (v-IGA) ≥3 at the screening and baseline visits.

• Worst-Itch Numerical Rating Scale (WI-NRS) weekly average score ≥4 in the 7 days before randomization.

• Documented recent history (within 6 months before the screening visit) of inadequate response* to treatment with topical medications or for whom topical treatments are otherwise medically inadvisable (eg, because of important side effects or safety risks).

  *Inadequate response to topical therapy is defined as persistent moderate-to-severe AD (EASI ≥16, vIGA-AD ≥3, BSA ≥10%) despite ≥4 weeks of optimized topical anti-inflammatory treatment (medium/high potency corticosteroids ± calcineurin inhibitors), or documented intolerance/contraindication to such therapies.

• For adolescents (≥12 and <18 years old) only, body weight ≥60 kg.

Exclusion Criteria:

• Any history or presence of severe concomitant illness(es) that, in the Investigator's judgment, would adversely affect the participant's participation in the study. Examples include, but are not limited to participants with short life expectancy, participants with uncontrolled diabetes (hemoglobin A1c ≥9%), participants with cardiovascular conditions (e.g, cardiomyopathy, thromboembolism, Class III or IV cardiac failure according to the New York Heart Association classification), severe hematological conditions (e.g. hyperviscosity), severe renal conditions (e.g, participants on dialysis), hepato-biliary conditions (e.g, Child-Pugh class B or C), neurological conditions (e.g, demyelinating diseases), active major autoimmune diseases (e.g, lupus, inflammatory bowel disease, rheumatoid arthritis, etc), other severe endocrinological, gastrointestinal, metabolic, pulmonary, or lymphatic diseases. The specific justification for participants excluded under this criterion will be noted in study documents (chart notes, case report forms [CRF], etc).
• Active chronic or acute infection requiring treatment with systemic antibiotics, antivirals, antiparasitics, antiprotozoals, or antifungals within 2 weeks before the baseline visit, or superficial skin infections within 1 week before the baseline visit. NOTE: participants may be rescreened after infection resolves.
• Known or suspected history of immunosuppression, including history of invasive opportunistic infections (eg, tuberculosis [TB], histoplasmosis, listeriosis, coccidioidomycosis, pneumocystosis, aspergillosis) despite infection resolution: or unusually frequent, recurrent, or prolonged infections, suggesting immunocompromised status per Investigator judgment.
• Presence of any skin comorbidities other than AD that, in the opinion of the Investigator, may interfere with the assessment of the study outcomes. For example: scabies, insect bite, folliculitis, lymphomatoid papulosis, chronic actinic dermatitis, dermatitis herpetiformis, sporotrichosis, bullous disease, or others.
• History of malignancy within 5 years before the screening visit, except completely treated in situ carcinoma of the cervix, completely treated and resolved non-metastatic squamous or basal cell carcinoma of the skin.
• Diagnosed with, suspected of, or at high risk for endoparasitic infection, and/or use of antiparasitic drugs within 2 weeks before Screening (Visit 1) or during the Screening period.
• Previously treated with marketed dupilumab or having received dupilumab in a prior dupilumab clinical study.

The above information is not intended to contain all considerations relevant to a participant's potential participation in a clinical trial.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Dupilumab coformulated with berahyaluronidase alfa; dupilumab coformulated with berahyaluronidase alfa SC injection as per protocol	Drug: Dupilumab coformulated with berahyaluronidase alfa; Pharmaceutical form: solution for injection Route of administration: SC injection; Other Names: SAR231893 + ALT-B4
Active Comparator: Dupilumab approved formulation; Approved dupilumab SC injection as per protocol	Drug: Dupilumab; Pharmaceutical form: solution for injection Route of administration: SC injection; Other Names: SAR231893

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Ctrough,ss at Week 20	Concentration observed before treatment administration during repeated dosing at steady state (SS).	Week 20

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
AUC0-4 weeks,ss	Area under curve from time point 0 to 28 days at steady state	Week 0 through Week 4
Cmax,ss	Maximum observed concentration during repeated dosing at steady state.	Week 20
Incidence of TEAEs, TE-AESIs, TE-SAEs, and TEAEs leading to permanent treatment discontinuation in the treatment-emergent period	TEAEs: treatment-emergent adverse events TE-AESIs: treatment-emergent adverse events of special interest TE-SAE: treatment-emergent serious adverse events	Week 0 up to week 32
Incidence of potentially clinically significant abnormalities in laboratory test, vital signs, and ECGs abnormalities in the treatment-emergent period		Week 0 up to week 32
Incidence of treatment-emergent anti-drug antibody (ADA) to dupilumab through Week 20		Week 0 up to week 20
Incidence of treatment-emergent ADA to ALT-B4 through Week 20		Week 0 up to week 20

Collaborators and Investigators

• Sponsor: Sanofi
• Collaborators: Regeneron Pharmaceuticals

Study record dates

Study Major Dates

• Study Start (Estimated): November 30, 2026
• Primary Completion (Estimated): May 2, 2028
• Study Completion (Estimated): July 25, 2028

Study Registration Dates

• First Submitted: October 30, 2026
• First Submitted That Met QC Criteria: October 30, 2026
• First Posted (Actual): November 5, 2026

Study Record Updates

• Last Update Posted (Actual): November 5, 2026
• Last Update Submitted That Met QC Criteria: October 30, 2026
• Last Verified: October 1, 2026

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Genetic Diseases, Inborn; Immune System Diseases; Hypersensitivity, Immediate; Hypersensitivity; Skin Diseases; Skin Diseases, Genetic; Skin Diseases, Eczematous; Dermatitis; Congenital, Hereditary, and Neonatal Diseases and Abnormalities; Skin and Connective Tissue Diseases; Dermatitis, Atopic; dupilumab
• Other Study ID Numbers: EFC20385; 2026-526619-13 (Registry Identifier: CTIS); U1111-1333-0202 (Registry Identifier: ICTRP)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES

IPD Plan Description

Qualified researchers may request access to patient level data and related study documents including the clinical study report, study protocol with any amendments, blank case report form, statistical analysis plan, and dataset specifications. Patient level data will be anonymized and study documents will be redacted to protect the privacy of trial participants. Further details on Sanofi's data sharing criteria, eligible studies, and process for requesting access can be found at: https://vivli.org

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: Yes
• Studies a U.S. FDA-regulated device product: No