The TERT Promoter is Polycomb-Repressed in Neuroblastoma Cells with Long Telomeres.

Acquiring a telomere maintenance mechanism is a hallmark of high-risk neuroblastoma and commonly occurs by expressing telomerase (TERT). Telomerase-negative neuroblastoma has long telomeres and utilizes the telomerase-independent alternative lengthening of telomeres (ALT) mechanism. Conversely, no discernable telomere maintenance mechanism is detected in a fraction of neuroblastoma with long telomeres. Here, we show, unlike most cancers, DNA of the TERT promoter is broadly hypomethylated in neuroblastoma. In telomerase-positive neuroblastoma cells, the hypomethylated DNA promoter is approximately 1.5 kb. The TERT locus shows active chromatin marks with low enrichment for the repressive mark, H3K27me3. MYCN, a commonly amplified oncogene in neuroblstoma, binds to the promoter and induces TERT expression. Strikingly, in neuroblastoma with long telomeres, the hypomethylated region spans the entire TERT locus, including multiple nearby genes with enrichment for the repressive H3K27me3 chromatin mark. Furthermore, subtelomeric regions showed enrichment of repressive chromatin marks in neuroblastomas with long telomeres relative to those with short telomeres. These repressive marks were even more evident at the genic loci, suggesting a telomere position effect (TPE). Inhibiting H3K27 methylation by three different EZH2 inhibitors induced the expression of TERT in cell lines with long telomeres and H3K27me3 marks in the promoter region. EZH2 inhibition facilitated MYCN binding to the TERT promoter in neuroblastoma cells with long telomeres. Taken together, these data suggest that epigenetic regulation of TERT expression differs in neuroblastoma depending on the telomere maintenance status, and H3K27 methylation is important in repressing TERT expression in neuroblastoma with long telomeres. SIGNIFICANCE: The epigenetic landscape of the TERT locus is unique in neuroblastoma. The DNA at the TERT locus, unlike other cancer cells and similar to normal cells, are hypomethylated in telomerase-positive neuroblastoma cells. The TERT locus is repressed by polycomb repressive complex-2 complex in neuroblastoma cells that have long telomeres and do not express TERT. Long telomeres in neuroblastoma cells are also associated with repressive chromatin states at the chromosomal termini, suggesting TPE.

An integrated single-cell RNA-seq map of human neuroblastoma tumors and preclinical models uncovers divergent mesenchymal-like gene expression programs.

BACKGROUND: Neuroblastoma is a common pediatric cancer, where preclinical studies suggest that a mesenchymal-like gene expression program contributes to chemotherapy resistance. However, clinical outcomes remain poor, implying we need a better understanding of the relationship between patient tumor heterogeneity and preclinical models. RESULTS: Here, we generate single-cell RNA-seq maps of neuroblastoma cell lines, patient-derived xenograft models (PDX), and a genetically engineered mouse model (GEMM). We develop an unsupervised machine learning approach ("automatic consensus nonnegative matrix factorization" (acNMF)) to compare the gene expression programs found in preclinical models to a large cohort of patient tumors. We confirm a weakly expressed, mesenchymal-like program in otherwise adrenergic cancer cells in some pre-treated high-risk patient tumors, but this appears distinct from the presumptive drug-resistance mesenchymal programs evident in cell lines. Surprisingly, however, this weak-mesenchymal-like program is maintained in PDX and could be chemotherapy-induced in our GEMM after only 24 h, suggesting an uncharacterized therapy-escape mechanism. CONCLUSIONS: Collectively, our findings improve the understanding of how neuroblastoma patient tumor heterogeneity is reflected in preclinical models, provides a comprehensive integrated resource, and a generalizable set of computational methodologies for the joint analysis of clinical and pre-clinical single-cell RNA-seq datasets.

An integrated single-cell RNA-seq map of human neuroblastoma tumors and preclinical models uncovers divergent mesenchymal-like gene expression programs.

Neuroblastoma is a common pediatric cancer, where preclinical studies suggest that a mesenchymal-like gene expression program contributes to chemotherapy resistance. However, clinical outcomes remain poor, implying we need a better understanding of the relationship between patient tumor heterogeneity and preclinical models. Here, we generated single-cell RNA-seq maps of neuroblastoma cell lines, patient-derived xenograft models (PDX), and a genetically engineered mouse model (GEMM). We developed an unsupervised machine learning approach ('automatic consensus nonnegative matrix factorization' (acNMF)) to compare the gene expression programs found in preclinical models to a large cohort of patient tumors. We confirmed a weakly expressed, mesenchymal-like program in otherwise adrenergic cancer cells in some pre-treated high-risk patient tumors, but this appears distinct from the presumptive drug-resistance mesenchymal programs evident in cell lines. Surprisingly however, this weak-mesenchymal-like program was maintained in PDX and could be chemotherapy-induced in our GEMM after only 24 hours, suggesting an uncharacterized therapy-escape mechanism. Collectively, our findings improve the understanding of how neuroblastoma patient tumor heterogeneity is reflected in preclinical models, provides a comprehensive integrated resource, and a generalizable set of computational methodologies for the joint analysis of clinical and pre-clinical single-cell RNA-seq datasets.

Bone morphogenetic protein (BMP) signaling determines neuroblastoma cell fate and sensitivity to retinoic acid.

Retinoic acid (RA) is a standard-of-care neuroblastoma drug thought to be effective by inducing differentiation. Curiously, RA has little effect on primary human tumors during upfront treatment but can eliminate neuroblastoma cells from the bone marrow during post-chemo consolidation therapy-a discrepancy that has never been explained. To investigate this, we treated a large cohort of neuroblastoma cell lines with RA and observed that the most RA-sensitive cells predominantly undergo apoptosis or senescence, rather than differentiation. We conducted genome-wide CRISPR knockout screens under RA treatment, which identified BMP signaling as controlling the apoptosis/senescence vs differentiation cell fate decision and determining RA's overall potency. We then discovered that BMP signaling activity is markedly higher in neuroblastoma patient samples at bone marrow metastatic sites, providing a plausible explanation for RA's ability to clear neuroblastoma cells specifically from the bone marrow, seemingly mimicking interactions between BMP and RA during normal development.

Advancements in the development of radiopharmaceuticals for nuclear medicine applications in the treatment of bone metastases.

Bone metastases are a painful and complex condition that overwhelmingly impacts the prognosis and quality of life of cancer patients. Over the years, nuclear medicine has made remarkable progress in the diagnosis and management of bone metastases. This review aims to provide a comprehensive overview of the recent advancements in nuclear medicine for the diagnosis and management of bone metastases. Furthermore, the review explores the role of targeted radiopharmaceuticals in nuclear medicine for bone metastases, focusing on radiolabeled molecules that are designed to selectively target biomarkers associated with bone metastases, including osteocytes, osteoblasts, and metastatic cells. The applications of radionuclide-based therapies, such as strontium-89 (Sr-89) and radium-223 (Ra-223), are also discussed. This review also highlights the potential of theranostic approaches for bone metastases, enabling personalized treatment strategies based on individual patient characteristics. Importantly, the clinical applications and outcomes of nuclear medicine in osseous metastatic disease are discussed. This includes the assessment of treatment response, predictive and prognostic value of imaging biomarkers, and the impact of nuclear medicine on patient management and outcomes. The review identifies current challenges and future perspectives on the role of nuclear medicine in treating bone metastases. It addresses limitations in imaging resolution, radiotracer availability, radiation safety, and the need for standardized protocols. The review concludes by emphasizing the need for further research and advancements in imaging technology, radiopharmaceutical development, and integration of nuclear medicine with other treatment modalities. In summary, advancements in nuclear medicine have significantly improved the diagnosis and management of osseous metastatic disease and future developements in the integration of innovative imaging modalities, targeted radiopharmaceuticals, radionuclide production, theranostic approaches, and advanced image analysis techniques hold great promise in improving patient outcomes and enhancing personalized care for individuals with bone metastases.

Prognostic Effect of Mismatch Repair Status in Early-Stage Endometrial Cancer Treated With Adjuvant Radiation: A Multi-institutional Analysis.

PURPOSE: The aim of this work was to report the effect of mismatch repair (MMR) status on outcomes of patients with stage I-II endometrioid endometrial adenocarcinoma (EEC) who receive adjuvant radiation therapy. METHODS AND MATERIALS: This is a multi-institutional retrospective cohort study across 11 institutions in North America. Patients with known MMR status and stage I-II EEC status postsurgical staging were included. Overall survival (OS) and recurrence-free survival (RFS) rates were estimated via the Kaplan-Meier method. Univariable and multivariable analyses were performed via Cox proportional hazard models for RFS and OS. Statistical analyses were conducted using SPSS version 27. RESULTS: In total, 744 patients with a median age at diagnosis of 65 years (IQR, 58-71) were included. Most patients were White (69.4%) and had Federation of Obstetrics and Gynecology 2009 stage I (84%) and Federation of Obstetrics and Gynecology grade 1 to 2 (73%). MMR deficiency was reported in 234 patients (31.5%), whereas 510 patients (68.5%) had preserved MMR. External beam radiation therapy with or without vaginal brachytherapy was delivered to 186 patients (25%), whereas 558 patients (75%) received vaginal brachytherapy alone. At a median follow-up of 43.5 months, the estimated crude OS and RFS rates for the entire cohort were 92.5% and 84%, respectively. MMR status was significantly correlated with RFS. RFS was inferior for MMR deficiency compared with preserved MMR (74.3% vs 88.6%, P < .001). However, no difference in OS was seen (90.8% vs 93.2%, P = .5). On multivariable analysis, MMR deficiency status was associated with worse RFS (hazard ratio, 1.86; P = .001) but not OS. CONCLUSIONS: MMR status was independently associated with RFS but not OS in patients with early-stage EEC who were treated with adjuvant radiation therapy. These findings suggest that differential approaches to surveillance and/or treatment based on MMR status could be warranted.

Latent Epigenetic Programs in Müller Glia Contribute to Stress, Injury, and Disease Response in the Retina.

Previous studies have demonstrated the dynamic changes in chromatin structure during retinal development that correlate with changes in gene expression. However, a major limitation of those prior studies was the lack of cellular resolution. Here, we integrate single-cell (sc) RNA-seq and scATAC-seq with bulk retinal data sets to identify cell type-specific changes in the chromatin structure during development. Although most genes' promoter activity is strongly correlated with chromatin accessibility, we discovered several hundred genes that were transcriptionally silent but had accessible chromatin at their promoters. Most of those silent/accessible gene promoters were in the Müller glial cells. The Müller cells are radial glia of the retina and perform a variety of essential functions to maintain retinal homeostasis and respond to stress, injury, or disease. The silent/accessible genes in Müller glia are enriched in pathways related to inflammation, angiogenesis, and other types of cell-cell signaling and were rapidly activated when we tested 15 different physiologically relevant conditions to mimic retinal stress, injury, or disease in human and murine retinae. We refer to these as "pliancy genes" because they allow the Müller glia to rapidly change their gene expression and cellular state in response to different types of retinal insults. The Müller glial cell pliancy program is established during development, and we demonstrate that pliancy genes are necessary and sufficient for regulating inflammation in the murine retina in vivo. In zebrafish, Müller glia can de-differentiate and form retinal progenitor cells that replace lost neurons. The pro-inflammatory pliancy gene cascade is not activated in zebrafish Müller glia following injury, and we propose a model in which species-specific pliancy programs underly the differential response to retinal damage in species that can regenerate retinal neurons (zebrafish) versus those that cannot (humans and mice).

Identification of Evolutionarily Conserved VSX2 Enhancers in Retinal Development.

Super-enhancers (SEs) are expansive regions of genomic DNA that regulate the expression of genes involved in cell identity and cell fate. Recently, we found that distinct modules within a murine SE regulate gene expression of master regulatory transcription factor Vsx2 in a developmental stage- and cell-type specific manner. Vsx2 is expressed in retinal progenitor cells as well as differentiated bipolar neurons and Müller glia. Mutations in VSX2 in humans and mice lead to microphthalmia due to a defect in retinal progenitor cell proliferation. Deletion of a single module within the Vsx2 SE leads to microphthalmia. Deletion of a separate module within the SE leads to a complete loss of bipolar neurons, yet the remainder of the retina develops normally. Furthermore, the Vsx2 SE is evolutionarily conserved in vertebrates, suggesting that these modules are important for retinal development across species. In the present study, we examine the ability of these modules to drive retinal development between species. By inserting the human build of one Vsx2 SE module into a mouse with microphthalmia, eye size was rescued. To understand the implications of these SE modules in a model of human development, we generated human retinal organoids. Deleting one module results in small organoids, recapitulating the small-eyed phenotype of mice with microphthalmia, while deletion of the other module leads to a complete loss of ON cone bipolar neurons. This prototypical SE serves as a model for uncoupling developmental stage- and cell-type specific effects of neurogenic transcription factors with complex expression patterns. Moreover, by elucidating the gene regulatory mechanisms, we can begin to examine how dysregulation of these mechanisms contributes to phenotypic diversity and disease.

Translational roadmap for regenerative therapies of eye disease.

The translation of regenerative therapies to neuronal eye diseases requires a roadmap specific to the nature of the target diseases, patient population, methodologies for assessing outcome, and other factors. This commentary focuses on critical issues for translating regenerative eye therapies relevant to retinal neurons to human clinical trials.

Change in stage after neoadjuvant chemoradiation is associated with survival in patients with esophageal cancer.

BACKGROUND: The aim of this study was to determine if change in stage after neoadjuvant chemoradiation (CRT) was associated with improved survival in esophageal cancer using a national database. METHODS: Using the National Cancer Database, patients with non-metastatic, resectable esophageal cancer who received neoadjuvant CRT and surgery were identified. Comparing clinical to the pathologic stage, change in stage was classified as pathologic complete response (pCR), downstaged, same-staged, or upstaged. Univariable and multivariable Cox regression models were used to identify factors associated with survival. RESULTS: A total of 7745 patients were identified. The median overall survival (OS) was 34.9 months. Median OS was 60.3 months if pCR, 39.1 months if downstaged, 28.3 months if same-staged, and 23.4 months if upstaged (p < 0.0001). On multivariable analysis, pCR was associated with improved OS compared to the other groups (downstaged: hazard ratio [HR]: 1.32 [95% confidence interval [CI]: 1.18-1.46]; same-staged: HR: 1.89 [95% CI: 1.68-2.13]; upstaged: HR: 2.54 [95% CI: 2.25-2.86]; all p < 0.0001). CONCLUSIONS: In this large database study, change in stage after neoadjuvant CRT was strongly associated with survival for patients with non-metastatic, resectable esophageal cancer. There was a significant stepwise decline in survival, in descending order of pCR, downstaged tumor, same-staged tumor, and upstaged tumor.

Association between hospital safety-net burden and receipt of trimodality therapy and survival for patients with esophageal cancer.

BACKGROUND: To examine the relationship between hospital safety-net burden and (1) receipt of surgery after chemoradiation (trimodality therapy) and (2) survival in esophageal cancer patients. METHODS: The National Cancer Database was queried to identify 22,842 clinical stage II to IVa esophageal cancer patients diagnosed in 2004 to 2015. The treatment facilities were categorized by proportion of uninsured/Medicaid-insured patients into percentiles. No safety-net burden hospitals (0-37th percentile) treated no uninsured/Medicaid-insured patients, whereas low (38-75th percentile) and high (76-100th percentile) safety-net burden hospitals treated a median (range) of 8.8% (0.87%-16.7%) and 23.6% (16.8%-100%), respectively. Adjusted odds ratios and hazard ratios with 95% confidence intervals were computed, adjusting for patient, tumor, and treatment characteristics. RESULTS: Compared to no safety-net burden hospital patients, high safety-net burden hospital patients were significantly more likely to be young, Black, and low-income. Age, female sex, Black race, Hispanic ethnicity, nonprivate insurance, lower income, higher comorbidity score, upper esophageal location, squamous cell histology, higher stage, time to treatment, and treatment at a community program or a low-volume facility were associated with lower odds of receiving trimodality therapy. Adjusting for these factors, high safety-net burden hospital patients were less likely to receive surgery after chemoradiation versus no safety-net burden hospital patients (adjusted odds ratio 0.77 [95% confidence interval 0.68-0.86], P < .0001); no difference was detected comparing low safety-net burden hospitals versus no safety-net burden hospitals (adjusted odds ratio 1.01 [0.92-1.11], P = .874). No significant survival difference was noted by safety-net burden (low safety-net burden hospitals versus no safety-net burden hospitals: adjusted hazard ratio 1.01 [0.96-1.06], P = .704; high safety-net burden hospital versus no safety-net burden hospitals: adjusted hazard ratio 0.99 [0.93-1.06], P = .859). CONCLUSION: Adjusting for patient, tumor, and treatment factors, high safety-net burden hospital patients were less likely to undergo surgery after chemoradiation but without significant survival differences.

Inequalities in Cancer Stage at Diagnosis Among Incarcerated Individuals Undergoing Radiation Therapy at a Large Safety-Net Hospital.

INTRODUCTION: There is a dearth of data on cancer care in the incarcerated population, despite being the leading cause of illness-related death in United states' prisons. We retrospectively reviewed the demographic and clinicopathologic characteristics of incarcerated individuals who received radiation therapy at a large safety-net hospital. METHODS: Following IRB approval, we identified 80 incarcerated patients who presented for radiation therapy between January 2003 and May 2019. Descriptive statistics on the patients, tumor types and stage, treatment factors, and follow-up rates were analyzed. RESULTS: 80 individuals with 82 cancer diagnoses presented for radiation oncology consultation over the study period. The median age was 54 years (range, 46-64). Patients of White, Black, and "other" races comprised 61.3% (n=49), 28.8% (n=23), and 10% (n=8), respectively. Most patients were male (n=75, 93.8%) and English speakers (n=76, 95%). Moreover, 50% (n=40) had a substance use disorder history and 75% (n=60) had a smoking history. The three most common cancer types were prostate (n=12, 14.6%), gastrointestinal (n=14, 17.1%), thoracic (n=17, 20.7%), and head and neck (n=21, 25.6%). The distribution of tumor stage (AJCC) was I (n=12, 14.6%), II (n=12, 14.6%), III (n=14, 17.1%), IV (n=38, 46.3%), and unknown/unavailable (n=6, 7.3%). Of the cohort, 65 patients with 66 cancers (80.5%) received radiation. Among them, the 6-month, 1-year, and 5-year follow-up rates were 41.5%, 27.7%, and 3.1%, respectively. Subset analysis limited to stage I-III patients (n=30) revealed 6-month, 1-year and 5-year follow-up rates of 41.9%, 22.6%, and 3.2%, respectively. CONCLUSIONS: This study highlights inequalities in cancer stage at diagnosis among a vulnerable patient population that is largely excluded from clinical research. Majority of the incarcerated patients presented with stage III & IV cancers and have poor follow up rates even among those with early-stage disease. Efforts to understand and mitigate persistent health inequalities among incarcerated patients are warranted.

WeWhoCurie: An Initiative to Advocate for Those Underrepresented in Radiation Oncology.

Purpose: An initiative to advocate for those underrepresented in radiation oncology. Methods and Materials: Inspired by the success of the #ILookLikeAnEngineer and #ILookLikeASurgeon campaigns, this initiative aimed to break down stereotypes in traditionally male-dominated fields. In honor of Marie Curie's birthday, on November 7, 2018, the Society for Women in Radiation Oncology launched a social media campaign called #WomenWhoCurie day. However, as the popularity of the social media campaign increased, it become evident that members of the wider radiation community, in particular women of color, nonbinary and transgender people did not feel supported by the #WomenWhoCurie movement. In November 2021, after consultation with diversity and inclusion leaders and members of other national radiation oncology organizations, Society for Women in Radiation Oncology launched #WeWhoCurie alongside the #WomenWhoCurie campaign for women and gender minorities in radiation oncology. Radiation oncologists, physicists, dosimetrist, therapists, nurses, and other professionals from around the world gathered and shared photos and social media posts throughout the day on multiple platforms including Facebook, Instagram, and Twitter. Results: In the year #WeWhoCurie, #WomenWhoCurie, #_______ WhoCurie campaign launched, we saw an increase in participation across the globe from 9 countries: the United States, Canada, Mexico, Brazil, Italy, Spain, China, New Zealand, and Australia. There were over 720 tweets contributing to the campaign with over 2000 messages, representing 3,365,444 "potential impacts", or the number of times someone saw the hashtag. Conclusions: Through this campaign we aim to celebrate the incredible women, gender minorities, and allies who are "Curie-ing" patients with cancer and conducting cutting edge research to improve cancer care across the globe. As an organization we believe adding our voices to the masses will foster a culture of inclusion for everyone. Afterall, what good is the practice of radiation oncology if all are not equally welcome?

Longitudinal Outcomes of Medical Student Research Mentorship: a 15-Year Analysis of the Radiation Oncology Mentorship Initiative.

At our institution, students can be mentored by radiation oncology faculty through structured research programs, such as the Medical Student Summer Research Program (MSSRP). The purpose of this study is to report the research productivity of students who engaged in radiation oncology research mentorship, whether through the MSSRP or other avenues of research mentorship. We compiled a database of abstracts and manuscripts co-authored by 58 students who conducted research with radiation oncology faculty from 2005 to 2020. The means, medians, ranges, and interquartile ranges (IQR) of co-authorships and first authorships were calculated for the overall cohort and compared for MSSRP and non-MSSRP students, who matched into radiation oncology and those who did not, and male versus female students. Among all 58 students, 106 abstracts and 70 manuscripts were identified. Of those students, 54 (93.1%) published at least one abstract or manuscript. The mean number of abstract co-authorships per student was 3.07 (median 2, range 0-25, IQR 0-4), and the mean number of manuscript co-authorships per student was 2.22 (median 1, range 0-18, IQR 1-3). There were no significant differences in research output between MSSRP and non-MSSRP students or male and female students. However, the students who matched into radiation oncology published more co-author (3.67 vs. 1.63, p = 0.01) and first-author (1.62 vs. 0.53, p = 0.006) manuscripts than those who did not. Further research is warranted to assess whether skills gained from student-directed research translate into residency and beyond.

Catheter reconstruction and dosimetric verification of MRI-only treatment planning (MRTP) for interstitial HDR brachytherapy using PETRA sequence.

Objective. The feasibility of MRI-only treatment planning (MRTP) for interstitial high-dose rate (HDR) brachytherapy (BT) was investigated for patients diagnosed with gynecologic cancer.Approach. A clinical MRTP workflow utilizing a 'pointwise encoding time reduction with radial acquisition (PETRA)' sequence was proposed. This is a clinically available MRI sequence optimized to improve interstitial catheter-tissue contrast. Interstitial needles outside the obturator region were reconstructed using MR images only. For catheters penetrating through the obturator, a library-based reconstruction was proposed. In this work, dwell coordinates from the clinical CT-based reconstruction were used as the surrogate for the library-based approach. For MR-only plan, dwell times were activated and assigned as in the clinical plans. The catheter reconstruction was assessed by comparing dwell position coordinates. The dosimetric comparisons between a clinical plan and MR-only plan were assessed for physical and EQD2 dose and volume parameters forD90,D50andD98for clinical target volume (CTV) andD2cc,D0.1ccandD5ccfor OARs.Main results. Catheter reconstruction was possible using the optimized PETRA sequence on MR images. An overall reconstruction difference of 1.7 ± 0.5 mm, attributed to registration-based errors, was found compared to the CT-based reconstruction. The MRTP workflow has the potential to generate a treatment plan with an equivalent dosimetric quality compared to the conventional CT/MRI-based approach. For CTVD90, physical and EQD2 dose and volume parameter differences were 1.5 ± 1.9% and 0.7 ± 1.0 Gy, respectively. ForD2ccOARs, DVH (EQD2) differences were -0.4 ± 1.1% (-0.2 ± 0.5 Gy), 0.5 ± 2.8% (0.2 ± 1.3 Gy) and -0.5 ± 1.4% (-0.2 ± 0.5 Gy) for rectum, bladder, and sigmoid, respectively.Significance. With the proposed MRTP approach, CT imaging may no longer be needed in HDR BT for interstitial gynecologic treatment. A proof-of-concept study was conducted to demonstrated that MRTP using PETRA is feasible, with comparable dosimetric results to the conventional CT/MRI-based approach.

Vision-Dependent and -Independent Molecular Maturation of Mouse Retinal Ganglion Cells.

The development and connectivity of retinal ganglion cells (RGCs), the retina's sole output neurons, are patterned by activity-independent transcriptional programs and activity-dependent remodeling. To inventory the molecular correlates of these influences, we applied high-throughput single-cell RNA sequencing (scRNA-seq) to mouse RGCs at six embryonic and postnatal ages. We identified temporally regulated modules of genes that correlate with, and likely regulate, multiple phases of RGC development, ranging from differentiation and axon guidance to synaptic recognition and refinement. Some of these genes are expressed broadly while others, including key transcription factors and recognition molecules, are selectively expressed by one or a few of the 45 transcriptomically distinct types defined previously in adult mice. Next, we used these results as a foundation to analyze the transcriptomes of RGCs in mice lacking visual experience due to dark rearing from birth or to mutations that ablate either bipolar or photoreceptor cells. 98.5% of visually deprived (VD) RGCs could be unequivocally assigned to a single RGC type based on their transcriptional profiles, demonstrating that visual activity is dispensable for acquisition and maintenance of RGC type identity. However, visual deprivation significantly reduced the transcriptomic distinctions among RGC types, implying that activity is required for complete RGC maturation or maintenance. Consistent with this notion, transcriptomic alternations in VD RGCs significantly overlapped with gene modules found in developing RGCs. Our results provide a resource for mechanistic analyses of RGC differentiation and maturation, and for investigating the role of activity in these processes.

Primary intracranial extraosseous Ewing's sarcoma of the skull base in an elderly adult: illustrative case.

BACKGROUND: Primary extraosseous intracranial Ewing's sarcoma, also known as a peripheral primitive neuroectodermal tumor or "small round blue cell tumor," is an extremely rare entity with limited representation in the literature beyond the pediatric population. OBSERVATIONS: A 67-year-old male suffering occipital headache, nausea, and gait disturbance was found to have a large, avidly contrast-enhancing cerebellopontine angle mass extending into the cervical spinal canal with associated mass effect on medulla, cerebellum, fourth ventricle, and cervical spinal cord. This mass was not present on the imaging from 8 years prior. He underwent surgical debulking and pathology results demonstrated a malignant small round cell tumor showing diffuse immunopositivity for cytokeratins, CD99 and NKX2.2 with EWRS1-FLI1 rearrangement in 84% of the nuclei confirmatory of Ewing's sarcoma. After 14 cycles of chemotherapy and 6 weeks of radiotherapy, 22 months after discovery, the patient remains in clinical and radiographic remission with complete return to his baseline functioning. LESSONS: Primary skull base extraosseous Ewing's sarcoma should be considered in the differential diagnosis even in the elderly population when imaging studies demonstrate aggressive tumor growth patterns. Tumor debulking to establish a diagnosis followed by adjuvant chemoradiation therapy can result in clinical improvement with remission.

Mesenchymal and adrenergic cell lineage states in neuroblastoma possess distinct immunogenic phenotypes.

Apart from the anti-GD2 antibody, immunotherapy for neuroblastoma has had limited success due to immune evasion mechanisms, coupled with an incomplete understanding of predictors of response. Here, from bulk and single-cell transcriptomic analyses, we identify a subset of neuroblastomas enriched for transcripts associated with immune activation and inhibition and show that these are predominantly characterized by gene expression signatures of the mesenchymal lineage state. By contrast, tumors expressing adrenergic lineage signatures are less immunogenic. The inherent presence or induction of the mesenchymal state through transcriptional reprogramming or therapy resistance is accompanied by innate and adaptive immune gene activation through epigenetic remodeling. Mesenchymal lineage cells promote T cell infiltration by secreting inflammatory cytokines, are efficiently targeted by cytotoxic T and natural killer cells and respond to immune checkpoint blockade. Together, we demonstrate that distinct immunogenic phenotypes define the divergent lineage states of neuroblastoma and highlight the immunogenic potential of the mesenchymal lineage.

Neuroblastoma: When differentiation goes awry.

Neuroblastoma is a leading cause of cancer-related death in children. Accumulated data suggest that differentiation arrest of the neural-crest-derived sympathoadrenal lineage contributes to neuroblastoma formation. The developmental arrest of these cell types explains many biological features of the disease, including its cellular heterogeneity, mutational spectrum, spontaneous regression, and response to drugs that induce tumor cell differentiation. In this review, we provide evidence that supports the notion that arrested neural-crest-derived progenitor cells give rise to neuroblastoma and discuss how this concept could be exploited for clinical management of the disease.