Citations

53BP1 nuclear bodies are dynamic structures with properties resembling biomolecular condensates, but the molecular determinants that govern 53BP1 higher-order assembly at DNA double-strand breaks (DSBs) remain to be established. Here, we show that 53BP1 condensation is stimulated by phosphatidylinositol 3-phosphate (PI(3)P) in vitro through a highly specific interaction with its C-terminal tandem BRCT domain (tBRCT). Consequently, mutational inactivation of the 53BP1 tBRCT domain compromised PI(3)P binding and suppressed 53BP1 optodroplet formation in vivo. We further show that rapid 53BP1 clustering following DNA damage precedes its stable assembly on DSB-flanking chromatin, requires its tBRCT, and is suppressed by sequestration of nuclear PI(3)P. Taken together, our findings identify PI(3)P binding as a mechanism that promotes the formation and maturation of 53BP1 condensate-like assemblies on damaged chromatin.

Abstract BRCA-associated homologous recombination deficiency (HRD) is present in ~ 50% of high-grade serous carcinomas (HGSC) and predicts sensitivity to platinum-based therapy. However, there is little understanding of why some patients with BRCA-deficient tumors experience unexpectedly poor outcomes. We profiled 154 tumors, enriched for patients with BRCA-deficient tumors that experienced short overall survival (≤ 3 years, n = 42), using whole-genome, transcriptome, and methylation analyses. All but one BRCA-deficient tumor exceeded an accepted HRD genomic scarring threshold. However, patients with BRCA1-deficient HGSC with a more elevated HRD score survived significantly longer. Patients with BRCA2-deficient HGSC and loss of NF1 survived twice as long as those without NF1 loss, whereas PIK3CA or RAD21 amplification defined BRCA2-deficient HGSC with exceptionally short survival. BRCA1-deficient tumors in short survivors had evidence of immunosuppressive c-kit signaling and EMT. In a large HGSC cohort (n = 1,389) including 282 individuals with pathogenic germline BRCA variants (gBRCApv), the location of the mutation within functional domains stratified clinical outcomes. Notably, residual disease after primary surgery had limited prognostic effect in gBRCApv-carriers compared to non-carriers. Our findings indicate that tumor HR proficiency in the context of therapy response and survival is not a binary property, and highlight genomic and immune modifiers of outcomes in BRCA-deficient HGSC.

With the first series of PRRX1 -rearranged tumors published in 2019, the spectrum of these so-called fibroblastic tumors has been expanded. Since then, several smaller case series have been published; however, our understanding of them continues to be quite limited given their rarity. We herein studied 18 additional cases, the largest series to date. Eighteen tumors present in 9 male, 8 female, and 1 nonbinary patient with a median age of 35 years (range: 11 to 70 y) and involved the neck (5), the chest region (4), thigh (3), back (1), shoulder (1), forehead (1), lower leg (1), axilla (1), and the parapharyngeal region (1). Clinical follow-up (9/18 tumors; 50%; median: 10 mo; range: 4 to 40 mo) showed consistent indolent behavior without local recurrences or distant metastases. On morphology, these tumors were characterized by well-circumscription and distinctive peripheral crescent-shaped vessels. They were composed of uniform spindle and round cells growing in short fascicles within often densely hyalinized collagen lacking significant mitotic activity, necrosis, or cytologic atypia. Immunohistochemically, about half of the tested tumors expressed focal to rarely diffuse S100 with occasional co-expression of SOX10. Interestingly, almost half of the tested cases also showed complete loss of RB expression. All but 1 tumor harbored a PRRX1::NCOA1 fusion, while 1 case harbored a novel PRRX1::EP300 fusion. We herein provide additional data on these exceptionally uncommon tumors, expand their molecular spectrum, and compare them to their close morphologic mimics to aid in accurate diagnosis and avoid confusion with potentially more aggressive neoplasms.

Abstract Purpose: The purpose of this study was to evaluate RB1 expression and survival across ovarian carcinoma histotypes and how co-occurrence of BRCA1 or BRCA2 (BRCA) alterations and RB1 loss influences survival in tubo-ovarian high-grade serous carcinoma (HGSC). Experimental Design: RB1 protein expression was classified by immunohistochemistry in ovarian carcinomas of 7,436 patients from the Ovarian Tumor Tissue Analysis consortium. We examined RB1 expression and germline BRCA status in a subset of 1,134 HGSC, and related genotype to overall survival (OS), tumor-infiltrating CD8+ lymphocytes, and transcriptomic subtypes. Using CRISPR-Cas9, we deleted RB1 in HGSC cells with and without BRCA1 alterations to model co-loss with treatment response. We performed whole-genome and transcriptome data analyses on 126 patients with primary HGSC to characterize tumors with concurrent BRCA deficiency and RB1 loss. Results: RB1 loss was associated with longer OS in HGSC but with poorer prognosis in endometrioid ovarian carcinoma. Patients with HGSC harboring both RB1 loss and pathogenic germline BRCA variants had superior OS compared with patients with either alteration alone, and their median OS was three times longer than those without pathogenic BRCA variants and retained RB1 expression (9.3 vs. 3.1 years). Enhanced sensitivity to cisplatin and paclitaxel was seen in BRCA1-altered cells with RB1 knockout. Combined RB1 loss and BRCA deficiency correlated with transcriptional markers of enhanced IFN response, cell-cycle deregulation, and reduced epithelial–mesenchymal transition. CD8+ lymphocytes were most prevalent in BRCA-deficient HGSC with co-loss of RB1. Conclusions: Co-occurrence of RB1 loss and BRCA deficiency was associated with exceptionally long survival in patients with HGSC, potentially due to better treatment response and immune stimulation.

INTRODUCTION: Obesity is associated with cancer, including gastrointestinal (GI). Data from low (LICs) and lower-middle-income countries (MICs) are limited. METHODS: We utilized data from the Global Burden of Disease Study 2019 to determine the mortality from GI cancer risk of high body mass index (BMI) in these countries. RESULTS: Mortality rates of GI cancers from high BMI increased in LICs and lower MICs, while burdens decreased or remained stable in high and middle-income countries. DISCUSSION: The GI cancer-related burden from high BMI increased in LICs and lower MICs, necessitating a concerted effort to tackle the obesity pandemic.

The scarcity of liver grafts has prompted developments in living donor liver transplantations (LDLT), with previous literature illustrating similar outcomes in recipients compared to deceased donor transplants. However, significant concerns regarding living donor morbidity and mortality have yet to be examined comprehensively. This study aims to provide estimates of the incidence of various outcomes in living liver donors. In this meta-analysis, Medline and Embase were searched from inception to July 2022 for articles assessing the incidence of outcomes in LDLT donors. Complications in the included studies were classified into respective organ systems. Analysis of incidence was conducted using a generalized linear mixed model with Clopper-Pearson intervals. Eighty-seven articles involving 60,829 living liver donors were included. The overall pooled incidence of complications in LDLT donors was 24.7% (CI: 21.6%–28.1%). The incidence of minor complications was 17.3% (CI: 14.7%–20.3%), while the incidence of major complications was lower at 5.5% (CI: 4.5%–6.7%). The overall incidence of donor mortality was 0.06% (CI: 0.0%–0.1%) in 49,027 individuals. Psychological complications (7.6%, CI: 4.9%–11.5%) were the most common among LDLT donors, followed by wound-related (5.2%, CI: 4.4%–6.2%) and respiratory complications (4.9%, CI: 3.8%–6.3%). Conversely, cardiovascular complications had the lowest incidence among the subgroups at 0.8% (CI: 0.4%–1.3%). This study presents the incidence of post-LDLT outcomes in living liver donors, illustrating significant psychological, wound-related, and respiratory complications. While significant advancements in recent decades have contributed towards decreased morbidity in living donors, our findings call for targeted measures and continued efforts to ensure the safety and quality of life of liver donors post-LDLT.

9569 Background: Immune-checkpoint inhibitor (ICI) immunotherapy increases survival in patients with melanoma. Yet only half of the patients respond, and 10-40% of patients experience immune-related adverse events (irAEs). Previous studies have found a correlation between the development of an irAE and treatment response. Modifying the gut microbiome could positively affect response to ICIs and reduce toxicities. We sought to determine if the microbiome at the onset of treatment, during an irAE, and at 12 weeks, can predict the response or toxicity during ICI treatment for metastatic melanoma. Methods: Melanoma patients (pts) > 18 yo treated with ICI enrolled in a prospective observational cohort study at The Ohio State University Comprehensive Cancer Center Skin Cancer Clinic. Excluded were patients on corticosteroids at the start of ICI cycle 1, except for adrenal physiologic replacement. Stools were collected at baseline, within 2 days of an adverse event assessed by physician chart review using CTCAE (Common Terminology Criteria for Adverse Events) v5.0, and at 12 weeks. Response (ORR) to ICIs was assessed by Response Evaluation Criteria in Solid Tumors (RECIST v1.1) q12 weeks and progression-free survival recorded. Metagenomic whole-genome shotgun sequencing was performed on an Illumina NovaSeq 6000 and classified using HUMAnN3. The effect of microbe relative abundances on irAEs was modeled by logistic regression with the R package glmm. Results: Of the 88 patients enrolled, 48 had metastatic disease with 32 assessable for response. ORR at 12 weeks was 28% (1 CR, 8 PR, 17 SD, and 6 PD) and 24 patients showed PFS at 12 months. Grade > 2 irAEs were observed in 11/48 pts. Abundance of Bacteroides dorei (False Discovery Rate Corrected p-value = 9.5E-07) and Blautia species CAG:257 (padj = 0.001) were enriched in responders, Prevotella Stercorea (padj = 1.1E-07) and a phage with a predicted target of Salmonella (padj = 8.3E-09) in non-responders. Responders with an irAE had enrichment of Bacteroides plebeius (padj = 4.2E-13) and Bacteroides coprophilus (padj = 0.0002) whereas responders without irAE had enrichment of Eubacterium siraeum (padj = 7.2E-05). Conclusions: Longitudinal and event-driven biospecimen collection in patients treated with ICIs showed several bacteria and viruses but no fungi associated with response, with and without the development of an irAE. The abundance of the two high-taxonomic rank microbe groups is significantly associated with irAEs. The association with the Bacteroides Genus is consistent with previous studies and is associated with response to ICIs. A microbiome abundant in Bacteroides and lacking Prevotella is associated with response to ICI. An abundance of Bacteroides could be a biomarker for irAEs, and an abundance of Eubacterium, a biomarker for response without irAEs. Future analyses are necessary to assign causal roles for microbe biomarkers with specific irAEs. Clinical trial information: NCT05102773 .

AbstractOur objective was to test whether p53 expression status is associated with survival for women diagnosed with the most common ovarian carcinoma histotypes (high‐grade serous carcinoma [HGSC], endometrioid carcinoma [EC], and clear cell carcinoma [CCC]) using a large multi‐institutional cohort from the Ovarian Tumor Tissue Analysis (OTTA) consortium. p53 expression was assessed on 6,678 cases represented on tissue microarrays from 25 participating OTTA study sites using a previously validated immunohistochemical (IHC) assay as a surrogate for the presence and functional effect of TP53 mutations. Three abnormal expression patterns (overexpression, complete absence, and cytoplasmic) and the normal (wild type) pattern were recorded. Survival analyses were performed by histotype. The frequency of abnormal p53 expression was 93.4% (4,630/4,957) in HGSC compared to 11.9% (116/973) in EC and 11.5% (86/748) in CCC. In HGSC, there were no differences in overall survival across the abnormal p53 expression patterns. However, in EC and CCC, abnormal p53 expression was associated with an increased risk of death for women diagnosed with EC in multivariate analysis compared to normal p53 as the reference (hazard ratio [HR] = 2.18, 95% confidence interval [CI] 1.36–3.47, p = 0.0011) and with CCC (HR = 1.57, 95% CI 1.11–2.22, p = 0.012). Abnormal p53 was also associated with shorter overall survival in The International Federation of Gynecology and Obstetrics stage I/II EC and CCC. Our study provides further evidence that functional groups of TP53 mutations assessed by abnormal surrogate p53 IHC patterns are not associated with survival in HGSC. In contrast, we validate that abnormal p53 IHC is a strong independent prognostic marker for EC and demonstrate for the first time an independent prognostic association of abnormal p53 IHC with overall survival in patients with CCC.

AbstractBackgroundCyclin E1 (CCNE1) is a potential predictive marker and therapeutic target in tubo‐ovarian high‐grade serous carcinoma (HGSC). Smaller studies have revealed unfavorable associations for CCNE1 amplification and CCNE1 overexpression with survival, but to date no large‐scale, histotype‐specific validation has been performed. The hypothesis was that high‐level amplification of CCNE1 and CCNE1 overexpression, as well as a combination of the two, are linked to shorter overall survival in HGSC.MethodsWithin the Ovarian Tumor Tissue Analysis consortium, amplification status and protein level in 3029 HGSC cases and mRNA expression in 2419 samples were investigated.ResultsHigh‐level amplification (>8 copies by chromogenic in situ hybridization) was found in 8.6% of HGSC and overexpression (>60% with at least 5% demonstrating strong intensity by immunohistochemistry) was found in 22.4%. CCNE1 high‐level amplification and overexpression both were linked to shorter overall survival in multivariate survival analysis adjusted for age and stage, with hazard stratification by study (hazard ratio [HR], 1.26; 95% CI, 1.08‐1.47, p = .034, and HR, 1.18; 95% CI, 1.05‐1.32, p = .015, respectively). This was also true for cases with combined high‐level amplification/overexpression (HR, 1.26; 95% CI, 1.09‐1.47, p = .033). CCNE1 mRNA expression was not associated with overall survival (HR, 1.00 per 1‐SD increase; 95% CI, 0.94‐1.06; p = .58). CCNE1 high‐level amplification is mutually exclusive with the presence of germline BRCA1/2 pathogenic variants and shows an inverse association to RB1 loss.ConclusionThis study provides large‐scale validation that CCNE1 high‐level amplification is associated with shorter survival, supporting its utility as a prognostic biomarker in HGSC.