FAP × GPC1 Bispecific ADC (BCG026)

FAP × GPC1 Dual-Target ADC Strategy for Stromal and Tumor Cell Engagement

• Stroma–tumor dual targeting: BCG026 is designed to target both GPC1-expressing tumor cells and FAP-positive cancer-associated fibroblasts (CAFs), supporting payload delivery across stromal barriers and addressing tumor heterogeneity in solid tumors.
• CAF-mediated bystander killing: By leveraging FAP-positive stromal cells, BCG026 is designed to extend cytotoxic activity to nearby antigen-negative tumor cells through a bystander killing mechanism.
• Broad solid tumor relevance: FAP is commonly expressed in the tumor stroma of many epithelial cancers, while GPC1 is aberrantly expressed in multiple tumor types, supporting the potential application of BCG026 across solid tumors.
• Competitive differentiation: BCG026 is a bispecific ADC that combines GPC1-targeted tumor cell killing, FAP-mediated stromal targeting, and bystander killing to address the tumor microenvironment in solid tumors.

RenLite® Fully Human Common Light Chain Antibody Backbone

Built on the RenLite® platform, BCG026 utilizes common light chain technology to eliminate heavy/light chain mispairing, ensure seamless assembly, simplify manufacturing, and provide a developable antibody backbone for the FAP × GPC1 bispecific ADC drug development.

Proprietary BLD1102 Linker–Payload Design for ADC Drug Development

BCG026 is conjugated with Biocytogen’s proprietary BLD1102 linker–payload system containing BCPT02, a topoisomerase I (TOP1) inhibitor payload designed to drive potent ADC-mediated cytotoxicity in solid tumor drug development.

• Payload-driven cytotoxic coverage: BCPT02 combines high payload potency with strong bystander killing to eliminate both target-positive and neighboring tumor cells.
• Developability-oriented linker design: BLD1102 linker is designed for superior hydrophilicity, controlled payload release, and high circulation stability, enhancing ADC developability and therapeutic performance.

Excellent Preclinical Performance

• The BCG026 bispecific antibody backbone demonstrated high binding activity to both FAP and GPC1, with efficient internalization across stromal and tumor cells.
• BCG026 induced cytotoxicity against FAP-positive CAFs and triggered CAF-mediated bystander killing of nearby FAP/GPC1-negative tumor cells in vitro (Figure 3).
• In pancreatic and lung cancer PDX models, BCG026 showed potent efficacy and superior synergistic effects compared with parental and combinational ADCs (Figure 4).

Potential Indications

BCG026 is being evaluated as a FAP/GPC1-directed bispecific ADC drug development asset for solid tumors. Potential development areas include pancreatic cancer, non-small cell lung cancer (NSCLC), and esophageal cancer.

The supporting preclinical data package for BCG026 include strong binding activity to both stromal and tumor cells, efficient internalization of the bispecific antibody backbone, a CAF-mediated bystander killing effect, and synergistic in vivo efficacy in multiple PDX models, supporting the development of BCG026 as a novel FAP × GPC1 bispecific ADC for solid tumors, with a primary focus on pancreatic cancer.

FAP × GPC1 Bispecific Antibody Binding Activity in Stromal and Tumor Cells

Figure 1. Antigen binding analysis of the FAP × GPC1 bispecific antibody across target-expressing cell lines. The FAP×GPC1 bispecific antibody demonstrated binding activity comparable to its respective parental antibodies in FAP/GPC1 co-expressing cells (FAP-GPC1-MC38), FAP single-positive CAFs (pancreatic CAF), and GPC1 single-positive cells (NCI-H1792), supporting preserved dual-target engagement across stromal and tumor cell contexts.

(Note: mv, monovalent; MIL-38-analog, GPC1 benchmark antibody; OMTX-705 Ab-analog, FAP benchmark antibody.)

BCG026 Bispecific Antibody Backbone Exhibits Efficient Internalization

Figure 2. Internalization kinetics of the BCG026 FAP × GPC1 bispecific antibody backbone in stromal and tumor cell lines. Internalization was evaluated in MC38 and NCI-H1792 cells, as well as pancreatic CAFs, with different FAP and GPC1 expression levels. The BCG026 bsAb showed efficient internalization across these models, with activity comparable to or higher than parental antibody controls, supporting the FAP × GPC1 bispecific antibody design for ADC payload delivery.

BCG026 Exhibits a CAF-Mediated Bystander Killing Effect

Figure 3. Bystander killing activity of BCG026 in FAP-positive CAFs and FAP/GPC1-negative tumor cells. BCG026 induced cytotoxic activity in FAP-positive CAFs and triggered CAF-mediated bystander killing of FAP/GPC1-negative HEP3B tumor cells, supporting its potential to eliminate antigen-negative tumor cells through stromal cell–mediated payload delivery.

BCG026 Demonstrates Synergistic Antitumor Efficacy in PDX Models

Figure 4. Antitumor efficacy of BCG026 (~DAR8) in PDX models with varying GPC1 and FAP-positive CAF expression levels. BCG026 showed superior tumor growth inhibition compared with single-target parental ADCs (GPC1 ADC and FAP ADC) administered individually or in combination, supporting the synergistic antitumor potential of the FAP × GPC1 bispecific ADC design targeting both tumor cells and the stromal compartment.

Biocytogen welcomes partnership discussions to further evaluate this FAP × GPC1 bispecific ADC asset.

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