Abstract LB218: Advanced ex vivo platform for drug response analysis: Evaluating the potent effects of NMC-521 mAb on mouse-and patient-derived organotypic tumor spheroids

Abstract In response to the high failure rate of new drugs in clinical trials, we have developed an innovative organotypic tumor spheroids platform, designed to mitigate the risks associated with advancing drugs to clinical stages. Utilizing patient-derived organotypic tumor spheroids (PDOTS), this platform uniquely captures both the phenotype and genotype of individual patient tumor microenvironments. This approach not only enhances the precision of preclinical models but also bridges the gap between laboratory research and clinical applicability. In this study, we assess the effectiveness of the first-in-class monoclonal antibody NMC-521 (NomoCan Pharmaceuticals, NY) using our ex vivo platform. Targeting the novel cancer-specific antigen NMC-1, NMC-521 exhibited significant growth inhibition of CT-26 tumors in syngeneic BALB/c mice, reducing tumor size by approximately 55% compared to the control. Similarly, in ex vivo settings with freshly excised CT-26 tumors (n=18), NMC-521 demonstrated a dose-dependent cytotoxic effect, achieving about a 65% reduction in tumor viability with an effective dose (ED50) of 10 µg/ml. Further insights were gained into NMC-521's mechanism of action using our ex vivo platform. The drug’s ability to induce tumor cell death in CT26 ex vivo was significantly reversed (p0. 01) when co-treated with α-NKG2D but not α-CD8, indicating a critical role for natural killer (NK) cells in its therapeutic effect. Complementing these findings, our analyses on freshly excised patient tumors (n=15) corroborated the cytotoxic effects of this drug on colorectal cancer but not to the same magnitude as in the CT-26 model. Furthermore, unlike the syngeneic murine tumor model, the response rate was (8 of 15 responsive patient tumors. Gene expression profiling indicated that NK cell-associated RNAs were elevated in NMC-521 treated PDOTS. Additionally, combination therapy studies using NMC-521 and nivolumab within our platform mirrored murine in vivo results, enhancing our understanding of the drug's potential in clinical settings. Intriguingly, an observed elevation in IL-15 levels in patient tumors treated with NMC-521 suggests an increased presence of NK cell activity when compared to treatments with nivolumab. This research underscores the potential of our organotypic tumor spheroids platform as a transformative tool in cancer drug development, offering an accurate and patient-specific method to evaluate new therapies, thereby increasing the likelihood of successful translation from the laboratory to patient care. Citation Format: Amir Aref, Alyssa Martin, Hamidreza Aboulkheyr Es, Patryk Krzesaj, Victor Adler, Kirti Khardenavis, Ehsan Sarafraz-Yazdi, Michael A. Perricone. Advanced ex vivo platform for drug response analysis: Evaluating the potent effects of NMC-521 mAb on mouse-and patient-derived organotypic tumor spheroids abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts) ; 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84 (7Suppl): Abstract nr LB218.