Abstract IA024: Cellular plasticity during metastatic colony formation in patients

Abstract

Abstract Systemic cancer spread is a process whose complexity is only poorly understood. We have learned over the past years that metastatic dissemination starts very early in the evolution of a malignant clone of most cancers and that disseminated cancer cells (DCC) continue to acquire genomic alterations at the distant site. Consequently, it seems plausible that cellular phenotypes change during metastatic colony formation as well, although the impact of genotype changes on the cellular phenotypes is not clear at all. We studied this process in malignant melanoma, exploiting the unique chance that routine sentinel lymph node (SLN) biopsies provide for a cancer that is diagnosed much earlier and at smaller size than most other cancers. Moreover, mouse models suggest that lymph nodes serve as exit routes for systemic dissemination of cancer cells and that their colonization indues tumor-immune tolerance promoting distal metastasis. Melanoma DCC enter SLNs and may or may not give rise to a metastatic colony. We therefore first assessed in a large patient cohort comprising more than 500 early-stage melanoma patients, which melanoma marker is best suited to identify candidate metastasis founder cells and then progressed to provide their detailed molecular characterization. We found that melanoma cellular phenotypes indeed change over metastatic colony formation, indicating that differential molecular stage-specific targeting may be required to prevent metastasis formation. Of note, we observed mechanisms of very early immune suppression via DCC-derived EVs suggesting early DCC must find immune-escape strategies at the metastatic site. Citation Format: Melanie Werner-Klein. Cellular plasticity during metastatic colony formation in patients [abstract]. In: Proceedings of the AACR Special Conference: Cancer Metastasis; 2022 Nov 14-17; Portland, OR. Philadelphia (PA): AACR; Cancer Res 2022;83(2 Suppl_2):Abstract nr IA024.