Nanobody MET CAR-T cells show efficacy in solid tumors.

Area of Science:

• Immunology
• Oncology
• Biotechnology

Background:

• MET overexpression drives solid tumor progression, invasion, metastasis, and chemoresistance.
• While antibody-drug conjugates targeting MET show promise, engineered cellular immunotherapies remain underexplored.
• Naturally occurring single-domain antibodies (VHH or nanobodies) offer advantages over scFvs, including smaller size, high specificity, and stability.

Purpose of the Study:

• To evaluate the efficacy of MET-targeting VHH-chimeric antigen receptor T cells (VHH-CART) as a novel cancer immunotherapy.
• To compare the performance of VHH-CART cells against MET-overexpressing tumors with existing therapeutic strategies.

Main Methods:

• Generated VHH-CART cells using mRNA electroporation.
• Assessed VHH-CART functionality through in vitro assays: cell binding avidity, cytokine production, cellular kinetics, and cytotoxicity.
• Evaluated therapeutic effectiveness in an in vivo mouse model of metastatic triple-negative breast cancer.

Main Results:

• VHH with intermediate avidity demonstrated optimal in vitro tumor killing.
• VHH-CART cells, utilizing the CD28 costimulatory domain, enhanced cytotoxicity while maintaining antigen density-dependent selectivity.
• Mechanistically, VHH-CARTs exhibited low tonic signaling, high avidity, potent cytokine release, and rapid tumor killing kinetics.
• In vivo, mRNA-delivered VHH-CARTs provided significant and sustained control of metastatic triple-negative breast cancer growth.

Conclusions:

• VHH-CART cells display robust tumor selectivity and potent therapeutic efficacy in both in vitro and in vivo settings.
• These findings establish VHH-CARTs as a promising immunotherapeutic strategy for targeting MET-overexpressing solid tumors.
• The unique properties of VHH, including stability and low tonic signaling, position VHH-CARTs as an advantageous approach for solid tumor CAR T-cell design.