Abstract 2607: Dual payload immunochemotherapy to treat CD276 positive cancers

Abstract The Cancer Genome Atlas (TCGA) dataset showed higher level of CD276 (B7-H3) transcript in multiple cancers, including triple-negative breast cancers (TNBCs), non-small cell lung cancers (NSCLCs) and other cancers, than normal tissues. Our immunohistochemistry staining of hundreds of patient tissue microarrays confirmed the high expression of CD276 surface receptor in >60% of TNBC and >70% of NSCLC while minimal or low expression in 33 normal organs or tissues. This study aims to develop and evaluate a novel treatment strategy, i.e. anti-CD276 mAb-dual payloads conjugate (DualADC), as immune-chemotherapy to treat CD276-positive TNBCs and NSCLCs. First, a new CD276-targeting monoclonal antibody (mAb) capable of delivering payloads and upregulating tumoral immunity was developed and engineered. Then, a new platform to concurrently conjugate both traditional cytotoxic payload and immunoregulating regent with one CD276 mAb (DualADC) was established. Our evaluations showed that this targeted therapy effectively killed multiple subtypes of TNBC and NSCLC, significantly upregulated immune functions in tumor microenvironment, and reduced tumor burden by up to 90-100% in seven animal models (including patient-derived xenograft). The post-treatment analysis using single-cell RNA sequencing, Luminex multiplex cytokine assay, whole blood, histology and histopathology analysis demonstrated an integrated anti-cancer mechanisms and minimal systematic toxicity. Altogether, our study suggested that the 276-DualADC could provide a promising targeted chemo-immunotherapy for CD276-postive cancer patients. In future, translational investigations will be performed to determine the toxicology, optimal dose, and treatment strategy, and the combination with other therapy will also be evaluated. Citation Format: Zhuoxin Zora Zhou, Jiashuai Zhang, Lufang Zhou, Xiaoguang Margaret Liu. Dual payload immunochemotherapy to treat CD276 positive cancers [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2607.