Abstract IA026: Epigenetic and genomic features define distinct cellular states with possible therapeutic relevance in osteosarcoma
Bibliographic record
Abstract
Abstract The Osteosarcoma (OS) genome is characterized by aneuploidy and dramatic structural rearrangements often leading to copy number gain and loss. Currently, all patients with osteoblastic OS at diagnosis are treated with the same highly toxic chemotherapy and no clinically relevant subtypes have been identified. While there is significant heterogeneity at the genome level between patients, less is known regarding epigenetic heterogeneity and how this may impact critical phenotypes such as therapy response and metastasis. To characterize the osteosarcoma epigenome, we integrated ATAC-seq and RNA-seq across a unique set of patient samples, PDXs and PDX-derived cell lines obtained across the disease continuum and including biopsies, resections, and metastasis. ATACseq analysis revealed the presence of two distinct epigenetic cell states (C1 and C2). Associating the differential genomic regions to likely regulated genes, the enriched pathways of Cluster 1 (C1) are related to mesenchymal cell proliferation, skeletal system morphogenesis, osteoblast differentiation, and Wnt signaling pathway. In contrast, Cluster 2 (C2) enriched pathways are related to cell motility and migration, extracellular matrix organization and regulation of protein serine/threonine kinase activity. Furthermore, accessible chromatin regions were enriched for a distinct set of transcription factor binding sites. We then assessed whether these epigenetic states were associated with response to targeted therapies. We identified unique vulnerability of C1 cell lines to AURK inhibitors whereas C2 cell lines had evidence for upregulation of MAPK and were vulnerable to treatment with trametinib. ATACseq analysis of PDX and a limited number of patient samples confirmed that these subtypes of OS also likely exist in patient tumors. In parallel to these studies, we have also carried out extensive additional analysis of vulnerability of OS cell ines to a wide range of targeted therapies. We find evidence for significant response to several inhibitors of the ATR-WEE1-CHK1 pathway nominating this as a potential novel vulnerability for OS. Therapeutic relevance of these findings is currently being explores in an orthotopic metastasis model of OS. Overall, our findings may define new subtypes of osteosarcoma with unique therapeutic vulnerabilities. Citation Format: E. Alejandro Sweet-Cordero. Epigenetic and genomic features define distinct cellular states with possible therapeutic relevance in osteosarcoma [abstract]. In: Proceedings of the AACR Special Conference: Sarcomas; 2022 May 9-12; Montreal, QC, Canada. Philadelphia (PA): AACR; Clin Cancer Res 2022;28(18_Suppl):Abstract nr IA026.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.003 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".