Novel bispecific antibody-drug conjugate targeting PD-L1 and B7-H3 enhances antitumor efficacy and promotes immune-mediated antitumor responses

BACKGROUND: Antibody-drug conjugates (ADCs) offer a promising approach, combining monoclonal antibodies with chemotherapeutic drugs to target cancer cells effectively while minimizing toxicity. METHODS: This study examined the therapeutic efficacy and potential mechanisms of a bispecific ADC (BsADC) in laryngeal squamous cell carcinoma. This BsADC selectively targets the immune checkpoints programmed cell death ligand-1 (PD-L1) and B7-H3, and the precise delivery of the small-molecule toxin monomethyl auristatin E. RESULTS: Our findings demonstrated that the BsADC outperformed its bispecific antibody and PD-L1 or B7-H3 ADC counterparts, particularly in terms of in vitro/in vivo tumor cytotoxicity, demonstrating remarkable immune cytotoxicity. Additionally, we observed potent activation of tumor-specific immunity and significant induction of markers of immunogenic cell death (ICD) and potential endoplasmic reticulum stress. CONCLUSION: In conclusion, this novel BsADC, through immune checkpoint inhibition and promotion of ICD, amplified durable tumor immune cytotoxicity, providing novel insights and potential avenues for future cancer treatments and overcoming resistance.