A Phase 1/2 Study of PRO-203 in Healthy Volunteers and Participants With Systemic Sclerosis.

NCT07641634 | Recruiting Phase 1

• 1 other identifier: PRO-203-101
• Study Type: interventional
• Target: 44
• Locations: 2 countries
• Sites: 3

Brief Summary

A two-part study of PRO-203 administered subcutaneously in healthy adult volunteers and participants with Systemic Sclerosis (SSc).

Conditions

Healthy Volunteers; Systemic Sclerosis (SSc); Scleroderma, Systemic; Scleroderma

Keywords

Systemic sclerosis; SSc; Scleroderma; B cell depletion

Outcome Measures

Primary Outcomes (1)

• Incidence of Adverse Events and Laboratory Abnormalities [Safety and Tolerability]

  Incidence and severity of treatment-emergent adverse events, serious adverse events, and dose-limiting toxicities, including changes in clinical laboratory values, ECGs, and vital signs.

  13 weeks (Part 1) / 49 weeks (Part 2)

Secondary Outcomes (3)

• Pharmacokinetics of PRO-203

  13 weeks (Part 1) / 49 weeks (Part 2)

• Pharmacodynamic-related biomarkers of PRO-203

  13 weeks (Part 1) / 49 weeks (Part 2)

• Immunogenicity of PRO-203

  13 weeks (Part 1) / 49 weeks (Part 2)

Other Outcomes (6)

• Modified Rodnan Skin Score (mRSS) (Part 2)

  13 weeks /49 weeks

• Revised Composite Response Index in Systemic Sclerosis (rCRISS) (Part 2)

  13 weeks / 49 weeks

• European Scleroderma Trials and Research Group Activity Index (EUSTAR-AI) (Part 2)

  13 weeks / 49 weeks

Study Arms (3)

Part 1: PRO-203

EXPERIMENTAL

Healthy participants receive single ascending dose of PRO-203 in dose escalation cohorts

Drug: PRO-203

Part 1: Placebo

PLACEBO COMPARATOR

Matching SC placebo administered to randomized Part 1 participants

Other: Placebo

Part 2: Multiple Doses of PRO-203

EXPERIMENTAL

Participants with systemic sclerosis receive a single cycle of PRO-203 across cohorts, including additional treatment as needed.

Drug: PRO-203

Interventions

PRO-203 DRUG

PRO-203 administered as escalating single dose in healthy participants or as a single cycle in participants with systemic sclerosis.

Part 1: PRO-203; Part 2: Multiple Doses of PRO-203

Placebo OTHER

Matching placebo comparator for Part 1 participants.

Part 1: Placebo

Eligibility Criteria

• Age: 18 Years - 65 Years
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• Is male or female, age 18 to 65 years, inclusive, at Screening.
• Able to provide Informed Consent.
• Absolute B cell count \> 25 cells/uL.
• In good general health, determined by no clinically significant findings in the of the investigator from medical history, physical examination, 12-lead ECG, clinical laboratory findings, and vital signs at Screening and Day -1 (participants with Gilbert's disease with associated abnormalities of liver function tests are eligible for enrollment).
• Up to date vaccination status per local guidelines (including but not limited to influenza vaccine, COVID booster and hepatitis B vaccine).
• Fulfill 2013 ACR/ EULAR criteria for classification of SSc with a total score of ≥ 9.
• Active disease defined as at least two of the following at screening:
• Disease duration ≤ 2 years (since onset of first-non-Raynaud-symptom), or
• Elevated acute phase reactant levels (CRP ≥ 6 mg/L, erythrocytes sedimentation rate \[ESR\] ≥ 28 mm/1h, or platelet count ≥ 330,000/µL), or
• Baseline mRSS ≥10 with evidence of progression, defined as mRSS increase at least 3 units, or involvement of 1 new body area and mRSS increase at least 2 units, or involvement of 2 new body areas (each within the previous 6 months), or
• ≥ 1 tendon friction rub, or
• Elevation of CK or aldolase \> 2 × the upper limit of normal (ULN) consistent with SSc-related myopathy, or
• Progressive fibrosing interstitial lung disease (ILD) as defined by at least one of the following criteria at any time within the prior 2 years:
• relative decline in forced vital capacity (FVC) % predicted ≥ 10%, or
• relative decline in FVC % predicted ≥ 5% to \<10% and worsened respiratory symptoms, or

You may not qualify if:

• Any clinically significant underlying illness in the opinion of the investigator.
• Active infection within 4 weeks prior to screening. Participants receiving IV antibiotics or having received IV antibiotics within 14 days prior to enrollment are excluded.
• Positive QuantiFERON-Gold TB test at screening.
• Plan to receive live, attenuated vaccine after signing ICF (inactive vaccines, such as the flu vaccine, are allowed).
• Evidence of malignant disease or malignancies diagnosed within the previous 5 years (except for treated local basal or squamous cell carcinoma of the skin or carcinoma in situ of the cervix uteri that had been excised and cured).
• Currently enrolled in another investigational device or drug study, or less than 30 days or 5 half-lives of the prior investigational agent (whichever is longer) have passed since ending another investigational device or drug study or plans to enroll in another investigational device or drug study during the course of this study.
• Social smokers e.g. up to 10 cigarettes per week (or equivalent amounts of nicotine containing products) and willing to abstain during inpatient stay, are allowed
• Use of any prescription medication within 14 days and OTC medications, vitamins, herbal medications (e.g., St. John's wort), or cannabis, except for contraceptive medications and as needed (prn) acetaminophen/paracetamol (not exceeding 2 grams/day) within 7 days prior to administration of the study drug and throughout the study.
• Rheumatic autoimmune disease other than SSc.
• Positive anti-centromere antibodies.
• Pulmonary disease with FVC ≤ 45% of predicted, or DLCO ≤ 35% of predicted.
• Class 2 or higher pulmonary arterial hypertension or evidence of other moderately severe pulmonary disease.
• Renal crisis within 6 months prior to Screening.
• Prior treatment with cellular immunotherapy (eg, CAR-T) or gene therapy product directed at any target.
• Previous treatment with chlorambucil, bone marrow transplantation, or total lymphoid irradiation.

Sponsors & Collaborators

• Prolium Bioscience, Inc: lead

Study Sites (3)

Nucleus Network

Melbourne, Victoria, 3004, Australia

COMPLETED

Peking University Third Hospital

Beijing, China

RECRUITING

Nanjing Drum Tower Hospital

Nanjing, China

RECRUITING

MeSH Terms

Conditions

Scleroderma, Systemic; Scleroderma, Diffuse

Condition Hierarchy (Ancestors)

Connective Tissue Diseases; Skin and Connective Tissue Diseases; Skin Diseases

Study Officials

• Salim Mujais

  Prolium Bioscience, Inc

  STUDY DIRECTOR

Central Study Contacts

Sergio Rodriguez

CONTACT

(646) 597-6980; info@proliumbio.com

Study Design

• Study Type: interventional
• Phase: phase 1
• Allocation: RANDOMIZED
• Masking: TRIPLE
• Who Masked: PARTICIPANT, INVESTIGATOR, OUTCOMES ASSESSOR
• Masking Details: Double (Participant, Investigator) - Part 1 only; Open Label - Part 2
• Purpose: TREATMENT
• Intervention Model: SEQUENTIAL
• Sponsor Type: INDUSTRY
• Responsible Party: SPONSOR

Model Details: Dose escalation

Study Record Dates

• First Submitted: December 10, 2025
• First Posted: June 11, 2026
• Study Start: October 27, 2025
• Primary Completion (Estimated): January 1, 2027
• Study Completion (Estimated): January 1, 2028
• Last Updated: June 18, 2026

Record last verified: 2026-06

Data Sharing

• IPD Sharing: Will share

Locations

AU (1); CN (2)