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Prolium Bioscience

A clinical-stage biotechnology company developing bispecific antibody therapies for severe autoimmune diseases. Prolium Bioscience focuses on T-cell engager antibodies designed to eliminate pathogenic B cells that drive autoimmune pathology.

Company Overview

Prolium Bioscience develops antibody therapies intended to treat autoimmune diseases through targeted immune cell depletion. Its strategy centers on bispecific antibodies that recruit T cells to eliminate B cells responsible for producing disease-driving autoantibodies.

The company was created to advance a single lead program targeting CD20-positive B cells and expand this approach to additional autoimmune conditions.

Headquarters and Global Presence

Prolium Bioscience is headquartered in New York, United States.

The company operates as a research-focused biotechnology organization conducting clinical development through international trial networks.

Founding and History

Prolium was created by the healthcare investment firm RTW Investments to develop antibody therapies targeting autoimmune diseases.

The company licensed global development rights to a CD20×CD3 bispecific antibody originally developed by KeyMed Biosciences and InnoCare Pharma, reflecting a broader trend of Western startups advancing assets discovered by Chinese biotechnology companies.

In 2026 the company launched publicly with a $50 million Series A financing to advance its lead clinical program.

Therapy Areas and Focus

Prolium’s development strategy focuses on autoimmune diseases driven by pathogenic B cells.

Key areas include:

Systemic sclerosis (scleroderma)
Systemic lupus erythematosus
Other severe B-cell–mediated autoimmune diseases

These indications are characterized by immune dysfunction involving autoreactive B cells and antibody-producing plasma cells.

Technology Platforms and Modalities

The company’s pipeline centers on bispecific antibody therapeutics.

Key modalities include:

CD20 × CD3 T-cell engager antibodies
Antibody-based immune-redirecting therapies targeting B cells

These antibodies bind CD20 on B cells and CD3 on T cells, bringing the two cell types into proximity and triggering immune-mediated elimination of the target B cells.

Key Pipeline Programs

Selected programs include:

PRO-203, a CD20 × CD3 bispecific antibody being developed for systemic sclerosis and other severe autoimmune diseases.

The program is being evaluated in early clinical studies, including a single-ascending-dose trial in healthy volunteers and investigator-initiated studies in lupus patients.

Key Personnel

Scott Requadt, Chief Executive Officer

Strategic Partnerships

Prolium’s lead program originates from a licensing agreement with KeyMed Biosciences and InnoCare Pharma. Under the agreement, Prolium obtained global rights to develop and commercialize the bispecific antibody in autoimmune indications, with potential milestone payments exceeding $500 million.

The company is backed by RTW Investments, which founded and financed the business to advance antibody therapies targeting autoimmune diseases.

FAQ Section

T-cell engagers have demonstrated strong immune-cell killing activity in oncology. Prolium is applying the same concept to autoimmune disease by redirecting T cells to eliminate B cells that produce pathogenic autoantibodies.

This approach aims to achieve deeper immune reset than traditional B-cell–targeting antibodies.

CD20 is expressed on most mature B cells and has been a validated target in both oncology and autoimmune medicine. Drugs such as rituximab already demonstrate that removing CD20-positive B cells can reduce disease activity in several autoimmune conditions.

Prolium’s therapy attempts to extend this concept using T-cell–redirecting antibodies.

PRO-203 is the company’s lead program and serves as the clinical test of its T-cell engager strategy. The antibody targets CD20 on B cells and CD3 on T cells, allowing the immune system to eliminate B cells directly.

Initial clinical work includes studies in systemic sclerosis and exploratory use in lupus patients.

Systemic sclerosis is a rare autoimmune disease characterized by immune dysregulation, fibrosis and vascular damage. Current treatments primarily manage symptoms rather than modifying the underlying immune pathology.

Targeting B cells more aggressively may offer a path toward disease-modifying therapies.

The agreement illustrates a growing industry pattern in which Western biotech startups license promising antibody programs discovered by Chinese biotechnology companies.

This model allows smaller companies to rapidly build clinical pipelines while providing original developers with milestone payments and royalties.

Prolium is an early clinical-stage biotechnology company launched in 2025. Its pipeline currently centers on a single lead antibody program and early clinical studies.

Much of the company’s near-term value depends on clinical data from this program.

Key developments include: