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EncompaSSc: Evaluation of MTX-474 in Participants With Diffuse Cutaneous Systemic Sclerosis (dcSSc)

A Phase 2 Randomized, Double-blind, Placebo-Controlled Study to Assess the Safety and Efficacy of MTX-474 in the Treatment of Participants With Diffuse Cutaneous Systemic Sclerosis (dcSSc)

Status
Recruiting
Phases
Phase 2
Study type
Interventional
Source
ClinicalTrials.gov
Registry ID
NCT07287670
Enrollment
85
Registered
2025-12-17
Start date
2026-04-16
Completion date
2028-12-01
Last updated
2026-06-04

For informational purposes only — not medical advice. Sourced from public registries and may not reflect the latest updates. Terms

Conditions

Diffuse Cutaneous Systemic Sclerosis

Keywords

MTX-474-S201, MTX-474, Diffuse Cutaneous Systemic Sclerosis, dcSSc participants, dcSSc, Adult, mRSS, EncompaSSc, monoclonal antibody, EphrinB2

Brief summary

A Phase 2 Randomized, Double-blind, Placebo-Controlled Study of the Safety and Efficacy of MTX-474 in Participants with Diffuse Cutaneous Systemic Sclerosis (dcSSc)

Detailed description

Participants with dcSSc who meet the study's inclusion and exclusion criteria will be randomly assigned in a 3:2 ratio to receive MTX-474 or a matching placebo by intravenous (IV) infusion. Concomitant use of one of the approved dcSSc therapies (immunosuppressive therapy, systemic glucocorticoids or other antifibrotic agents) is permitted under certain criteria. Participants randomized to the MTX-474 arm of the study will receive an IV infusion every 4 weeks, beginning at Day 0 and ending at Week 20. The End of Treatment Visit will occur at Week 24, and a Safety Follow-Up Visit will occur at Week 28, 8 weeks after the final infusion. mRSS assessments will occur at Screening, Baseline, and at all subsequent treatment visits up to and including Week 24. Spirometry will be performed at screening and Weeks 12. HRCT will be performed at screening and week 24. DLCO will be performed at Screening. Skin biopsies will be performed at Baseline and Week 12. Participants will have blood drawn for safety assessment and to assess Ephrin receptor levels at Screening, Baseline and every 4 weeks until Week 28. Blood will be drawn for serum PK analyses relative to the first and last doses of MTX-474.

Interventions

BIOLOGICALMTX-474

Dosage level: 4 mg/kg Unit dose strength: 50mg/ml MTX-474 is a human immunoglobulin G1 (IgG1) monoclonal antibody that binds the human EphrinB2 with high specificity and high affinity. MTX-474 is being developed as a therapy for patients with systemic sclerosis (SSc).

OTHERPlacebo

Placebo

Sponsors

Mediar Therapeutics
Lead SponsorINDUSTRY

Study design

Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
TREATMENT
Masking
QUADRUPLE (Subject, Caregiver, Investigator, Outcomes Assessor)

Eligibility

Sex/Gender
ALL
Age
18 Years to No maximum
Healthy volunteers
No

Inclusion criteria

1. Diagnosis of diffuse cutaneous systemic sclerosis, classified according to 2013 American College of Rheumatology/European League Against Rheumatism (ACR/EULAR) 2. Participant is either: 1. Within 2 years of their first non-Raynaud's symptom and their mRSS is \>7; OR 2. \>2 and ≤5 years from their first non-Raynaud's symptom, their mRSS is between 10 and 30, they are negative for the RNA polymerase 3 autoantibody, and (1) they have never had any previous spontaneous improvement in skin thickening of ≥4 points by mRSS on exams performed by the same clinician, or (2) they were never clinically noted to have a meaningful spontaneous reduction in skin thickness if mRSS was never done; OR 3. \>5 and ≤10 years from their first non-Raynaud's symptom, their mRSS is between \>15 and ≤25, they are negative for the RNA polymerase 3 autoantibody, and (1) they have never had any previous spontaneous improvement in skin thickening of ≥4 points by mRSS, or (2) were never clinically noted to have a meaningful spontaneous reduction in skin thickness if mRSS was never done. 3. Participant is ≥18 years of age at time of signing the ICF. 4. Able to understand the study and provide a signed, written ICF 5. Able to read and understand the language of the ICF and other study-related materials 6. Forced vital capacity (FVCpp) of ≥45 pp10 7. Have diffusing capacity of the lungs for carbon monoxide (DLCO) of ≥30 percent predicted at Screening 8. Willing and able to complete all protocol-required study visits and procedures 9. Participants of childbearing potential must have a negative serum pregnancy test at Screening. 10. All participants with reproductive potential must agree to use and follow medically approved, highly effective methods of contraception during treatment and until 5 half-lives or 125 days after the last dose, whichever is longer

Exclusion criteria

1. Concomitantly have another serious medical illness, which, in the opinion of the Investigator, would interfere with the participant's ability to complete the study 2. Participant is currently on immunosuppressive therapy, systemic glucocorticoids or other antifibrotic agents detailed as follows: 1. Immunosuppresive agents: Cyclophosphamide (IV or oral if used in the 6 months prior to Screening), calcineurin inhibitors (if used in the 30 days prior to Screening), azathioprine (if used in the 30 days prior to Screening), Janus-kinase inhibitors (if used in the 30 days prior to Screening), rituximab (if used in the 6 months prior to Screening), tocilizumab (if used in the 60 days prior to Screening) or any other biologic Disease-Modifying Antirheumatic Drugs (DMARD, if used in the last 30 days or 3 half-lives prior to Screening, whichever is longer) 2. Antifibrotic agents: nintedanib or pirfenidone (if used in the 30 days prior to Screening). Also, exclusionary if used within 3 months of Screening are tyrosine-kinase inhibitors with recognized anti-fibrotic activity (imatinib, nilotinib, etc.) 3. Systemic glucocorticoids: equivalent doses of prednisone greater than 10 mg/day (≤10 mg/day allowed). Has received any pulse intramuscular (IM) or intravenous (IV) steroid within 1 month of Screening 4. Other agents: i. mycophenolate mofetil unless on a stable dose for at least 6 months prior to Screening and there are no plans to adjust the dose during the study; ii. mycophenolic acid unless on a stable dose for at least 6 months prior to Screening and there are no plans to adjust the dose during the study; iii. hydroxychloroquine unless on a stable dose for at least 3 months prior to Screening and there are no plans to adjust the dose during the study; and iv. methotrexate unless on a stable dose for at least 3 months prior to Screening and there are no plans to adjust the dose during the study. 3. Previous or planned hematopoietic stem cell or solid organ transplantation 4. Previous treatment with chimeric antigen receptor (CAR)-T/CAR-NK therapy 5. Clinically significant PAH as determined by the Investigator at, or prior to first day of dosing (Baseline) 6. Current use of PAH medication (endothelin receptor antagonists, prostacyclin analogues, soluble guanylate cyclase stimulators) excluding calcium channel blockers and phosphodiesterase-5 inhibitors 7. Pregnant or currently breastfeeding 8. Aspartate transaminase (AST) or alanine transaminase (ALT) \>2.0 upper limit of normal 9. Creatinine clearance \<45mL/min 10. History of myocardial infarction, angina or congestive heart failure 11. International normalized ratio \>2 or partial thromboplastin time \>1.5 × upper limit of normal 12. Active infection with human immunodeficiency virus (HIV), hepatitis B, or hepatitis C 13. History of clinically significant thrombotic event within 12 months prior to Screening 14. Positive anticentromere antibody 15. Systemic sclerosis renal crisis within 12 months prior to Screening 16. Confirmed diagnosis of overlap syndrome, systemic lupus erythematosus with anti-double strand (ds)DNA antibody, rheumatoid arthritis with anti-cyclic citrullinated peptide (anti-CCP) antibody, or systemic sclerosis mimics (eosinophilic fasciitis, scleromyxedema) at the time of inclusion in the study 17. Known malignancy or history of malignancy within 5 years of Screening other than non-melanoma skin cancer and in situ cervical cancer 18. Major surgery within 8 weeks prior to Screening or planned surgery during study period 19. Unable to routinely access veins for blood draws and IV infusions 20. Currently receiving another experimental agent or participating in another clinical trial. If a participant has recently received another experimental agent, then the last dose must have been at least 5 half-lives or 30 days (whichever is longer) prior to Screening 21. History of myocardial infarction, angina or congestive heart failure

Design outcomes

Primary

MeasureTime frameDescription
Change from baseline in Modified Rodnan Skin Score (mRSS)Baseline to week 24Mean change from baseline to week 24 in the modified Rodnan Skin Score, a clinician-assessed measure of skin thickness across 17 body areas. Unit of measure: Score (range 0-51)

Secondary

MeasureTime frameDescription
Proportion of participants with a gene signature response in skin biopsy12 weeksProportion of participants in each arm (MTX-474 and placebo) demonstrating a dcSSc gene expression signature response on skin biopsy at Week 12. Unit of Measure: Participants (%)
Number of participants with clinically significant findings on physical examination, vital signs, and clinical laboratory testsBaseline through end of study (week 28)Number of participants with clinically significant findings on physical examination, vital signs, and clinical laboratory tests Unit of Measure: Participants (%)
Number of participants with dose interruptions or treatment discontinuations due to adverse eventsBaseline through end of study (week 28)Number of participants with dose interruptions or treatment discontinuations due to adverse events Unit of Measure: Participants (%)
Safety and tolerability of MTX-474 in participants with dcSSc: Number of participants with treatment-emergent adverse events (TEAEs) and treatment-related adverse events (TRAEs)Baseline through end of study (week 28)Incidence, seriousness, and severity of TEAEs and TRAEs as determined by investigator assessment. Unit of measure: Participants (%)
Serum concentration of MTX-474 at sparse PK time pointsBaseline to week 28Serum MTX-474 concentrations collected at predefined sparse PK time points to support population pharmacokinetic (popPK) analysis Unit of Measure: ng/mL
Clearance (CL) of MTX-474Baseline to week 28Clearance of MTX-474 calculated from serial PK sampling using noncompartmental analysis Unit of Measure: L/hour
Terminal elimination half-life (t½) of MTX-474Baseline to week 28Terminal elimination half-life of MTX-474 derived from serial PK sampling. Unit of Measure: Hours
Area under the plasma concentration-time curve (AUC) of MTX-474Baseline to week 28AUC of MTX-474 calculated from serial PK sampling using noncompartmental analysis. Unit of Measure: ng·h/mL

Countries

United States

Contacts

CONTACTJeffrey Bornstein, MD
jeffrey@mediartx.com(617) 936-0960

Outcome results

None listed

Source: ClinicalTrials.gov · Data processed: Jun 5, 2026