Significant increase of high-risk chromosome 1q gain and 6q loss at recurrence in posterior fossa group A ependymoma: A multicenter study

Cognitive Outcomes in Children Treated for Ependymoma Diagnosed Under 36 Months: A Systematic Review

It is crucial to understand the morbidity associated with treatments for young children with ependymoma given this is a high incidence age group also known to be at risk of poorer cognitive outcomes. This review aimed to identify the quality of existing evidence describing cognitive outcomes in children treated for ependymoma under 36 months of age with a particular focus on the impact of radiotherapy. Eight studies were identified. Given the quality and heterogeneity of methodology, studies were only suitable for qualitative synthesis, as the majority included small numbers of participants with multiple confounding factors. Whilst some studies reported poor cognitive outcomes, the only large study reporting planned irradiation reported outcomes below the population mean but still broadly in the average range. This was consistent with a further study of interest that did not meet inclusion criteria but reported outcomes for children treated under five years old, many of whom were likely in the target population age for this review. Overall, the length of follow-up was often limited, and further research to monitor long-term impact, including photon and proton irradiation protocols on cognitive development, is required. Importantly, there is an urgent need to agree homogeneous methodology and achieve international consensus for cognitive assessment protocols to interrogate cognitive outcomes in this vulnerable population.

Advances in molecular prognostication and treatments in ependymoma

Ependymoma is the third most common brain tumour of childhood and historically has posed a major challenge to both pediatric and adult neuro-oncologists. Ependymoma can occur anywhere in the central nervous system throughout the entire age spectrum. Treatment options have been limited to surgery and radiation, and outcomes have been widely disparate across studies. Indeed, these disparate outcomes have rendered it extraordinarily difficult to compare studies and to truly understand which patients are low and high-risk. Over the past two decades there have been tremendous advances in our understanding of the biology of ependymoma, which have changed risk stratification dramatically. Indeed, it is now well accepted that ependymoma comprises multiple distinct entities, whereby each compartment (supratentorial, posterior fossa, spinal) are distinct, and within each compartment there exist unique groups. The driver events, demographics and response to treatment vary widely across these groups and allow for a better classification of thee disease. Herein, we review the advances in the molecular stratification of ependymoma including how an improved classification and risk stratification allows for more precise therapies.

Conditional survival estimates for ependymomas reveal the dynamic nature of prognostication

BACKGROUND

Traditional survival analysis is frequently used to assess the prognosis of ependymomas (EPNs); however, it may not provide additional survival insights for patients who have survived for several years. Thus, the conditional survival (CS) pattern of this disease is yet to be further investigated. This study aimed to evaluate the improvement of survival over time using CS analysis and develop a CS-based nomogram model for real-time dynamic survival estimation for EPN patients.

METHODS

Data on patients with EPN were collected from the Surveillance, Epidemiology, and End Results (SEER) database. In order to construct and validate the model effectively, the selected patients were randomly divided at 7:3 ratio. CS is defined as the probability of surviving for a specified time period (y years) after initial diagnosis, given that the patient has survived x years. The CS pattern of EPN patients were explored. Then, the least absolute shrinkage and selection operator (LASSO) regression method with tenfold cross-validation was employed to identify prognostic predictors. Multivariate Cox regression was employed to develop a CS-based nomogram model, and we used this model to quantify EPN patient risk. Finally, the performance of the prediction model was also evaluated and verified.

RESULTS

In total, 1829 patients diagnosed with EPN were included in the study, with 1280 and 549 patients in the training and validation cohorts, respectively. The CS analysis demonstrated that patients' OS saw gradual improvements over time. With each additional year of survival post-diagnosis, the 10-year survival rate of EPN patients saw an increase, updating from 74% initially to 79%, 82%, 85%, 87%, 89%, 91%, 93%, 96%, and 98% (after surviving for 1-9 years, respectively). The LASSO regression model, which implements tenfold cross-validation, identified 7 significant predictors (age, tumor grade, tumor site, tumor extension, tumor size, surgery and radiotherapy) to develop a CS-based nomogram model. And further risk stratification was conducted based on nomogram model for these patients. Furthermore, this survival prediction model was successfully validated.

CONCLUSION

This study described the CS pattern of EPN patients and highlighted the gradual improvement of survival observed over time for long-term survivors. We also developed the first novel CS-nomogram model that enabled individualized and real-time prognosis prediction. But patients must be counselled that individual circumstances may not always accurately reflect the findings of the nomogram.

Development of Chromosome 1q+ Specific Treatment for Highest Risk Pediatric Posterior Fossa Ependymoma

PURPOSE

There are no effective treatment strategies for children with highest-risk posterior fossa group A ependymoma (PFA). Chromosome 1q gains (1q+) are present in approximately 25% of newly diagnosed PFA tumors, and this number doubles at recurrence. Seventy percent of children with chromosome 1q+ PFA will die because of the tumor, highlighting the urgent need to develop new therapeutic strategies for this population.

EXPERIMENTAL DESIGN

In this study, we utilize 1q+ PFA in vitro and in vivo models to test the efficacy of combination radiation and chemotherapy in a preclinical setting.

RESULTS

5-fluorouracil (5FU) enhances radiotherapy in 1q+ PFA cell lines. Specifically, 5FU increases p53 activity mediated by the extra copy of UCK2 located on chromosome 1q in 1q+ PFA. Experimental downregulation of UCK2 resulted in decreased 5FU sensitivity in 1q+ PFA cells. In in vitro studies, a combination of 5FU, retinoid tretinoin (ATRA), and radiation provided the greatest reduction in cellular proliferation and greatest increase in markers of apoptosis in 1q+ PFA cell lines compared with other treatment arms. Similarly, in vivo experiments demonstrated significant enhancement of survival in mice treated with combination radiation and 5FU and ATRA.

CONCLUSIONS

These results are the first to identify a chromosome 1q+ specific therapy approach in 1q+ PFA. Existing phase I studies have already established single-agent pediatric safety and dosages of 5FU and ATRA, allowing for expedited clinical application as phase II trials for children with high-risk PFA.

Clinically relevant molecular hallmarks of PFA ependymomas display intratumoral heterogeneity and correlate with tumor morphology

Posterior fossa type A (PF-EPN-A, PFA) ependymoma are aggressive tumors that mainly affect children and have a poor prognosis. Histopathology shows significant intratumoral heterogeneity, ranging from loose tissue to often sharply demarcated, extremely cell-dense tumor areas. To determine molecular differences in morphologically different areas and to understand their clinical significance, we analyzed 113 PF-EPN-A samples, including 40 corresponding relapse samples. Cell-dense areas ranged from 0 to 100% of the tumor area and displayed a higher proportion of proliferating tumor cells (p < 0.01). Clinically, cell density was associated with poor progression-free and overall survival (pPFS = 0.0026, pOS < 0.01). Molecularly, tumor areas with low and high cell density showed diverging DNA methylation profiles regarding their similarity to distinct previously discovered PF-EPN-A subtypes in 9/21 cases. Prognostically relevant chromosomal changes at 1q and 6q showed spatial heterogeneity within single tumors and were significantly enriched in cell-dense tumor areas as shown by single-cell RNA (scRNA)-sequencing as well as copy number profiling and fluorescence in situ hybridization (FISH) analyses of different tumor areas. Finally, spatial transcriptomics revealed cell-dense areas of different tumors to be more similar than various different areas of the same tumor. High-density areas distinctly overexpressed genes encoding histone proteins, WNT5A, TGFB1, or IGF2. Relapsing tumors displayed a higher proportion of cell-dense areas (p = 0.036), a change in PF-EPN-A methylation subtypes (13/32 patients), and novel chromosome 1q gains and 6q losses (12/32 cases) compared to corresponding primary tumors. Our data suggest that PF-EPN-A ependymomas habor a previously unrecognized intratumoral heterogeneity with clinical implications, which has to be accounted for when selecting diagnostic material, inter alia, by histological evaluation of the proportion of cell-dense areas.