Nanobody-Directed CEA-Targeting CAR T Cells Eliminate Gastrointestinal Cancer Xenografts

Area of Science:

• Oncology
• Immunotherapy
• Molecular Biology

Background:

• Gastrointestinal cancers (GICs) are a major global health burden, with limited treatment options for metastatic disease.
• Current therapies for advanced GICs often face challenges with resistance and efficacy.
• Chimeric antigen receptor (CAR) T-cell therapy has shown success in hematological malignancies but is still developing for solid tumors like GICs.

Purpose of the Study:

• To develop a novel CAR T-cell therapy targeting gastrointestinal cancers.
• To identify and validate a specific target antigen and develop a potent CAR construct for GICs.
• To evaluate the efficacy of the developed CAR T-cell therapy in preclinical models of GICs.

Main Methods:

• Utilized a tumor-selected antibody and antigen retrieval system to isolate a nanobody (VHHB30) targeting carcinoembryonic antigen (CEA).
• Engineered VHHB30-CAR T cells (CEACAR T cells) and compared third-generation with second-generation constructs.
• Assessed in vitro cytotoxicity against gastric and colorectal cancer cell lines.
• Evaluated in vivo antitumor activity in preclinical mouse models with GIC xenografts.

Main Results:

• VHHB30 specifically binds to the N-terminal domain of CEA.
• CEACAR T cells demonstrated CEA-dependent cytotoxicity against GIC cell lines in vitro.
• Third-generation CEACAR T cells exhibited superior antitumor activity compared to second-generation cells.
• In vivo studies showed complete eradication of various colorectal and gastric tumor xenografts by CEACAR T cells.

Conclusions:

• VHHB30-CAR T-cell therapy is a potent strategy against gastrointestinal cancers.
• The developed CEACAR T cells show significant promise for treating GICs in preclinical settings.
• This approach highlights the potential of unbiased in vivo selection for discovering effective CAR T-cell binders for solid tumors.