Triple-negative breast cancer (TNBC) is a highly aggressive and treatment-resistant malignancy characterized by the lack of targeted therapies and poor clinical outcomes. Here, we present a dual-targeting strategy combining the anti-EGFR monoclonal antibody cetuximab (CTX) with H-ferritin (HFn), a nanoparticle targeting transferrin receptor 1 (TfR1), for potential immunotherapy in CTX-resistant tumors. The HFn-CTX nanoconjugate exhibited favorable biophysical properties and good tumor accumulation and significantly enhanced antibody-dependent cellular cytotoxicity (ADCC) in TNBC spheroids compared to CTX alone. Conversely, glioblastoma spheroids did not exhibit comparable reactivity. This effect correlated with elevated cell-surface EGFR expression and plasma-membrane lingering of the nanoconjugate in TNBC cells, facilitating robust immune activation. Biodistribution studies showed selective accumulation of the HFn-CTX nanoconjugate in TNBC tumors in vivo. These findings highlight the potential of HFn-CTX nanoconjugates to repurpose CTX for refractory cancers that express EGFR at high levels, such as TNBC, leveraging dual-receptor targeting to amplify immune-mediated cytotoxicity and overcome resistance.

Triple-negative breast cancer (TNBC) is a highly aggressive and treatment-resistant malignancy, characterized by the lack of targeted therapies and poor clinical outcomes. Here, we present a dual-targeting strategy combining the anti-EGFR monoclonal antibody Cetuximab (CTX) with H-ferritin (HFn), a nanoparticle targeting transferrin receptor 1 (TfR1), for potential immunotherapy in CTX-resistant tumors. The HFn-CTX nanoconjugate exhibited favorable biophysical properties, including a hydrodynamic size of <30 nm, and significantly enhanced antibody-dependent cellular cytotoxicity (ADCC) in TNBC spheroids compared to CTX alone. Conversely, glioblastoma spheroids did not exhibit comparable reactivity. This effect correlated with elevated cell-surface EGFR expression and plasma-membrane lingering of the nanoconjugate in TNBC cells, facilitating robust immune activation. Biodistribution studies showed selective accumulation of the HFn-CTX nanoconjugate in TNBC tumors in vivo. These findings highlight the potential of HFn-CTX nanoconjugates to repurpose CTX for refractory cancers that express EGFR at high levels like TNBC, leveraging dual-receptor targeting to amplify immune-mediated cytotoxicity and overcome resistance.