Abstract A015: Exploiting endogenous replication stress with a novel targeted therapy in Ewing sarcoma
Bibliographic record
Abstract
Abstract Ewing sarcoma (EwS) is a rare and aggressive disease that typically affects the bone of children and young adults. Although there are moderate 5-year survival rates for primary disease, there is a high rate of recurrence and a lack of targeted therapies in this setting. Furthermore, pediatric exposure to chemotherapies leads to an increased risk of long-term complications, including secondary cancers, cardiomyopathy, and infertility. Therefore, there is a desperate need for targeted therapies which improve therapeutic outcomes and reduce exposure to chemotherapy in these patients. Like many pediatric cancers, EwS has a low mutational burden. Instead, it is driven by chromosomal translocation between a FET family member, EWSR1, and an ETS family member, usually FLI1. The EWSR1-FLI1 fusion protein acts as an aberrant and oncogenic transcription factor, disrupting cell cycle control, cell migration, and proliferation. ETS family members in these fusions retain their ability to bind to the SWI/SNF chromatin remodeling complex, further dysregulating DNA methylation and gene expression. Although targeting of the EWSR1 fusion has not yet been successful, these elevated levels of replication stress (RS) present a unique element of vulnerability within the cell. To this end, our lab has previously identified replication stress response (RSR) inhibitors, DDKi and WEE1i, which can be utilized to exploit the characteristic ability of EwS to maintain high levels of replication stress (RS) and push EwS cells into mitotic catastrophe in vitro. Here, we evaluate the efficacy of the replication stress response inhibitors (RSRi) TAK931 (DDKi) and MK1775 (WEE1i) with chemotherapy regimens commonly utilized in the relapsed/refractory setting in vivo. Using cell line derived xenografts in NSG mice, we show that DDKi and WEE1i with irinotecan limits tumor growth significantly more than existing therapy (temozolomide + irinotecan). Dosing schedules are optimized through dosing de-escalation and alternative-day dosing strategies. We further demonstrate the ability of our RSRi combination to effectively limit tumor growth over time in vivo even when irinotecan dosage is decreased. We go on to investigate the RSRi combination in the presence of ultra-low dose irinotecan. Finally, we utilize reduced representation bisulfite sequencing to examine the epigenetic effects of these treatment regimens. Overall, the exploitation of high endogenous replication stress in EwS by targeted RSRi presents a promising potential therapeutic option for this pediatric patient population. Citation Format: Emily Isenhart, Ajay Gupta, Bryan Gillard, Kristopher Attwood, Joyce Ohm. Exploiting endogenous replication stress with a novel targeted therapy in Ewing sarcoma [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Expanding and Translating Cancer Synthetic Vulnerabilities; 2024 Jun 10-13; Montreal, Quebec, Canada. Philadelphia (PA): AACR; Mol Cancer Ther 2024;23(6 Suppl):Abstract nr A015.
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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 | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| 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".