Nanobioconjugate Trispecific Antibody Augments Antitumor Immunity of Triple Negative Breast Cancer.

INTRODUCTION

Triple-negative breast cancer (TNBC) is characterized as the most unfavorable prognosis of the breast cancer subtype. Chemotherapy is currently the primary treatment owing to a persistent lack of effective alternative medicine. To fulfill this unaddressed clinical requirement, we utilized the PGLU-Fc-III-4C MsAb platform to develop a nanobioconjugate trispecific antibody (TsAb; CD3×CD137×CD276) that targeted CD3, CD137, and CD276, aiming to restrict the growth of TNBC tumors (4T1 model) and provide a novel therapeutic strategy.

METHODS

The capacity for binding to target cells and anti-tumor effects of TsAb in vitro were evaluated. In vivo antitumor efficacy and biosafety were further assessed in the 4T1 subcutaneous tumor model. Anti-tumor immune responses induced by TsAb on tumor-infiltrating CD8+ T cells were monitored.

RESULTS

The TsAb effectively bound and facilitated interactions between 4T1 tumor cells and T cells, significantly boosting the anti-tumor effect. TsAb promoted the expansion of tumor and splenic T lymphocytes and facilitated the recruitment of splenic and blood T lymphocytes to tumor tissues. Compared with the PGLU-Fc-III-4C-IgG treatment group, the TsAb treatment group had varying degrees of increase in CD8+ tissue-resident memory T cells (TRM), central memory T cells (TCM), and terminal effector memory T cells (TEM) in tumor tissues. The TsAb treatment group exhibited a significant increase of PD-1+ CD8+ T cells and TCF1-Tim-3+ CD8+ terminally exhausted T cells in tumor tissues. The safety profile demonstrated no obvious systemic toxicity.

DISCUSSION: Briefly, TsAb mediated CD8+ T cell activation, proliferation, and terminal differentiation, accompanied by increasing cytokine production to eliminate the tumor. Meanwhile, no obvious systemic toxicity was observed. In general, the CD3×CD137×CD276 nanobioconjugate trispecific antibody provides a promising immunotherapeutic approach via regulating CD8+ T cell immune response for the treatment of triple-negative breast cancer.