Abstract 5405: Integrative surfaceome profiling identifies MMP14, MRC2 and CD276 as candidate immunotherapeutic target in osteosarcomas
Authors: Wang Yifei , Zhang Zhongting , Zhang Wendong , Xu Zhaohui , Zhou Xin , Roth Michael , Gill Jonathan , Harrison Douglas , Hingorani Pooja , Kannan Sankar , Jusu Sylvester , Tian Xiangjun , Wang Jing , Lazcano Rossana , Lazar Alexander , Gorlick Richard 
Published: September 2020

Abstract
Osteosarcoma (OS) is the most common primary malignant bone tumor in pediatric patients. However, the survival rate of patients with osteosarcomas has not improved for the last several decades. Current developments in immunotherapeutic strategies may increase the efficacy of these treatments for solid tumors. However, these treatments, such as antibody-drug conjugates (ADCs) or CAR-T cell therapy have not been sufficiently studied in OS because of a lack of known tumor-specific target. In this study, we developed an integrative pipeline combining the transcriptomic data from OS patients and the cell-surface proteomics data generated from a panel of patient-derived OS cell lines and PDX models and relating these to normal tissue expression. RNA sequencing data from 40 high-risk OS patients treated at MD Anderson Cancer Center was pooled with 111 OS patients available through the public TARGET online database. All the tumor data was subsequently compared with normal tissue RNA-sequencing data from the NIH Genotype-Tissue Expression (GTEx) database. The significantly differentially expressed genes (log fold change tumor versus normal &gt;1.5 for each tissue, p &lt; 0.01) were selected. We further filtered this gene list by cell surface protein prediction based on the Compartments subcellular localization database. To determine protein expression levels, we prepared surface protein extracts from a panel of patient-derived OS cell lines and PDX models. Proteomic mass spectrometry was used to profile these OS surface proteins. We also included the proteomics data of OS tissue and 39 types of normal human organs via the public proteomic database. Integrative analysis of the transcriptomic and proteomic data demonstrated MMP14, MRC2, and CD276 are highly expressed in OS compared to normal tissues across all datasets. The expression of the three cell surface proteins was validated by IHC staining with an OS tissue microarray from 100 patients, and western blot with our PDX tissues and patient-derived cell lines. A previously reported preclinical study has shown the CD276 ADC (mCD276-PBD) has good antitumor activity against xenograft models of OS. Multiple preclinical tests including CD276 CAR-T cells, MRC2 ADC and MMP14 Bicycle Drug Conjugate (BT1718) are planned to further validate the therapeutic potential of these targets. Our current findings have not been previously reported in OS. The results might warrant further development of ADC and CAR-T cell therapy for osteosarcomas against these targets.
Citation Format: Yifei Wang, Zhongting Zhang, Wendong Zhang, Zhaohui Xu, Xin Zhou, Michael Roth, Jonathan Gill, Douglas Harrison, Pooja Hingorani, Sankar Kannan, Sylvester Jusu, Xiangjun Tian, Jing Wang, Rossana Lazcano, Alexander Lazar, Richard Gorlick. Integrative surfaceome profiling identifies MMP14, MRC2 and CD276 as candidate immunotherapeutic target in osteosarcomas [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 5405.