RHOA Loss of Function Impairs the IFNγ Response and Promotes CD19 Antigen Escape to Drive CAR-T Resistance in Diffuse...

Area of Science:

• Oncology
• Immunotherapy
• Molecular Biology

Background:

• Chimeric antigen receptor (CAR)-T cell therapy shows promise for aggressive B-cell lymphomas but durable responses are limited.
• Deletions in the RHOA gene are frequently observed in patients progressing after CAR-T therapy.
• RHOA's role in CAR-T resistance and lymphoma pathogenesis is not well understood.

Purpose of the Study:

• To investigate the mechanisms by which RHOA deficiency contributes to resistance against CD19-directed CAR-T cell therapy.
• To explore the impact of RHOA loss on cellular signaling pathways and immune cell interactions in the tumor microenvironment.

Main Methods:

• Generation of RHOA-deficient diffuse large B-cell lymphoma (DLBCL) cell systems for in vitro and in vivo studies.
• Assessment of CAR-T cell response, cellular signaling (AKT, interferon gamma), and CD19 expression.
• Analysis of tumor microenvironment composition, including T-cell infiltration and macrophage polarization, in immunocompetent mouse models.

Main Results:

• RHOA-deficient DLBCL cells exhibit intrinsic resistance to CAR-T cell therapy.
• RHOA loss leads to AKT activation, impaired interferon gamma responses, and down-regulation of CD19.
• RHOA-deficient tumors show increased sensitivity to AKT-pathway inhibitors, reversing interferon gamma response defects.
• In vivo, RHOA loss reduces cytotoxic T-cell infiltration and increases M2-polarized macrophages, indicating immune evasion.

Conclusions:

• RHOA deficiency is an AKT-mediated driver of CAR-T cell resistance in B-cell lymphomas.
• Loss of RHOA promotes immune evasion by reducing T-cell mediated killing, explaining its frequent occurrence in DLBCL.
• Targeting the AKT pathway offers a potential strategy to overcome RHOA-mediated CAR-T resistance.