Abstract A013: Osteosarcoma metastases develop as neo-organs, creating distinct ecosystems with divergent therapeutic vulnerabilities
Yogesh Budhathoki, Jeffrey P. Sheridan, Veronica Jarzabek, Matthew V. Cannon, Troy A. McEachron, Anand G. Patel, Matthew J. Gust, Daniel P. Regan, Heather L. Gardner, Ruben Dries, Ryan D. RobertsAbstract
Background:
Osteosarcoma lung metastases are the principal cause of osteosarcoma-related death, yet the processes by which these bone tumor cells colonize the distinct environment of the lung remain poorly defined. We hypothesized that osteosarcoma metastases develop through an organized, organogenesis-like process that produces spatially patterned "neo-organs" containing distinct cellular ecosystems with divergent therapeutic vulnerabilities.
Methods:
We integrated single-cell and spatial transcriptomic data from human, canine, and murine (PDX and syngeneic) osteosarcoma lung metastases spanning multiple stages of lesion development. Tumor cell states, host-cell reprogramming, and spatial architecture were characterized using unsupervised clustering, RNA velocity/regulon inference, and spatial deconvolution, then compared lesions arising within the same patients/animals, as well as comparing between animals/patients.
Results:
Osteosarcoma cells reproducibly adopt distinct, conserved transcriptional states: differentiated phenotypes with fibroblast-like and immune-like programs; less-differentiated phenotypes with distinct proliferative and metabolic signatures; and a novel phenotype restricted exclusively to regions of chondroid/osteoid matrix formation (COMA). As lesions develop, they progress through a patterned sequence, beginning with differentiated "edge" phenotypes, then incorporating less-differentiated "core" phenotypes, and finally acquiring COMA regions — establishing an inside-to-outside spatial hierarchy that mirrors organogenesis. Recruitment and reprogramming of host cells, which is well illustrated by changes epithelial cells and macrophages, follows a parallel spatial and temporal pattern, generating distinct cellular ecosystems within each region. This developmental patterning is superimposed on substantial inter-lesional heterogeneity: individual metastases arising within the same patient or animal diverge markedly from one another. These differences, however, are not random—each lesion instead appears to follow one of a handful of potential neo-organ developmental pathways. These distinct cellular ecosystems, and the inter-lesional phenotypes they compose, exhibit both predicted and experimentally observed differences in therapeutic sensitivity.
Conclusions:
Osteosarcoma metastases develop as spatially and temporally organized neo-organs, each built from a reproducible ecosystem of malignant and host cells that follows one of several conserved developmental trajectories. This structured heterogeneity, occurring both within and between lesions, likely contributes to mixed therapeutic responses, incomplete responses, and emergence of resistance, and points toward region- and lesion-specific combinatorial strategies for improving outcomes in metastatic osteosarcoma.
Citation Format:
Yogesh Budhathoki, Jeffrey P. Sheridan, Veronica Jarzabek, Matthew V. Cannon, Troy A. McEachron, Anand G. Patel, Matthew J. Gust, Daniel P. Regan, Heather L. Gardner, Ruben Dries, Ryan D. Roberts. Osteosarcoma metastases develop as neo-organs, creating distinct ecosystems with divergent therapeutic vulnerabilities [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Bridging Discovery and Clinical Impact in Pediatric Cancer; 2026 Sep 22-25; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2026;86(18_Suppl_1):Abstract nr A013.