Ovarian cancer is not a single disease and can be subdivided into at least five different 2 histological subtypes that have different identifiable risk factors, cells of origin, molecular compositions, clinical features and treatments. Ovarian cancer is a global problem, is typically diagnosed at late stage, and has no effective screening strategy. Standard treatments for newly diagnosed cancer consist of cytoreductive surgery and platinum-based chemotherapy. In recurrent cancer, chemotherapy, anti-angiogenic agents, and poly (ADP ribose) polymerase (PARP) inhibitors are used and immunological therapies are currently being tested. High-grade serous carcinoma (HGSC) is the most commonly diagnosed form of ovarian cancer and is typically very responsive to platinum-based chemotherapy at diagnosis. However, in addition to the other histologies, HGSCs frequently relapse and become increasingly resistant to chemotherapy.Consequently, understanding the mechanisms underlying platinum resistance and finding ways to overcome them are active areas of study in ovarian cancer. Significant progress has been made in identifying genes associated with high risk of ovarian cancer (such as BRCA1 and BRCA2) as well as a precursor lesion of HGSC called a serous tubal intraepithelial carcinoma, which hold promise for identifying individuals at high risk of developing the disease and for developing prevention strategies. Competing interestsU.A.M. has served as a consultant for AstraZeneca, ImmunoGen, Pfizer, Genentech, and Merck.

he Cancer Genome Atlas project identified 2 groups of endometrioid endometrial cancers (ECs) with high mutation frequency: an ultramutated group (7% of all tumors) that harbored mutations in the exonuclease domain of polymerase e (POLE), and a hypermutated group (28% of tumors) with microsatellite instability (MSI), the majority of which harbored MLH1 promoter methylation. 1 The ultramutated POLE group exhibited an extremely high mutation rate (232 × 10 −6 mutations/Mb) with a unique nucleotide change spectrum of increased C→A transversion frequency, whereas the hypermutated MSI group exhibited mutation rates of 18 × 10 −6 mutations/Mb with variable length of DNA microsatellites due to an underlying deficiency in mismatch DNA repair. [1][2][3] Mismatch DNA repair deficiency induces singlebase mismatches that lead to point mutations in coding regions of genes, as well as insertions or deletions that lead to frame-shift mutations.It has been suggested that hypermutated tumors may harbor more tumor-specific neoantigens and increased amounts of tumor-infiltrating lymphocytes (TILs). 3-7 Therefore, we assessed whether POLE and MSI ECs harbor more neoantigens and TILs than the comparatively hypomutated microsatellitestable (MSS) ECs. Methods Prediction of HLA Type and Neoantigen LoadInference of HLA type was performed using the POLY-SOLVER (polymorphic loci resolver) tool. 5 For prediction of neoantigen load, the Sage Bionetworks' Synapse resource (https://www.synapse.org and Lawrence et al 8 ) and the Net-MHCpan tool (version 2.4) 9 were used (eMethods in the Supplement).IMPORTANCE Immune checkpoint inhibitor therapy has shown benefit in various cancers, but their potential in endometrial cancer (EC) is unknown.OBSERVATIONS Prediction of neoantigen load was performed using sequencing data from the Cancer Genome Atlas data set. Evaluation of tumor-infiltrating lymphocytes (TILs) and PD-1 and PD-L1 expression was performed in 63 patients with EC referred to our institution. The predicted median (range) neoantigen load (predicted neoepitopes per sample

Immune checkpoint inhibitors (e.g., anti-PD-1 and anti-PD-L1 antibodies) have demonstrated remarkable efficacy against hypermutated cancers such as melanomas and lung carcinomas. One explanation for this effect is that hypermutated lesions harbor more tumor-specific neoantigens that stimulate recruitment of an increased number of tumor-infiltrating lymphocytes (TILs), which is counterbalanced by overexpression of immune checkpoints such as PD-1 or PD-L1. Given that BRCA1/2-mutated high grade serous ovarian cancers (HGSOCs) exhibit a higher mutational load and a unique mutational signature with an elevated number of larger indels up to 50 bp, we hypothesized that they may also harbor more tumor-specific neoantigens, and, therefore, exhibit increased TILs and PD-1/PD-L1 expression. Here, we report significantly higher predicted neoantigens in BRCA1/2-mutated tumors compared to tumors without alterations in homologous recombination (HR) genes (HR-proficient tumors). Tumors with higher neoantigen load were associated with improved overall survival and higher expression of immune genes associated with tumor cytotoxicity such as genes of the TCR, the IFN-gamma and the TNFR pathways. Furthermore, immunohistochemistry studies demonstrated that BRCA1/2-mutated tumors exhibited significantly increased CD3+ and CD8+ TILs, as well as elevated expression of PD-1 and PD-L1 in tumor-associated immune cells compared to HR-proficient tumors. Survival analysis showed that both BRCA1/2-mutation status and number of TILs were independently associated with outcome. Of note, two distinct groups of HGSOCs, one with very poor prognosis (HR proficient with low number of TILs) and one with very good prognosis (BRCA1/2-mutated tumors with high number of TILs) were defined. These findings support a link between BRCA1/2-mutation status, immunogenicity and survival, and suggesting that BRCA1/2-mutated HGSOCs may be more sensitive to PD-1/PD-L1 inhibitors compared to HR-proficient HGSOCs.

SummaryStem cells of the gastrointestinal tract, pancreas, liver, and other columnar epithelia collectively resist cloning in their elemental states. Here we demonstrate the cloning and propagation of highly clonogenic, “ground state” stem cells of the human intestine and colon. We show that derived stem cell pedigrees sustain limited copy number and sequence variation despite extensive serial passaging and display exquisitely precise, cell-autonomous commitment to epithelial differentiation consistent with their origins along the intestinal tract. This developmentally patterned and epigenetically maintained commitment of stem cells likely enforces the functional specificity of the adult intestinal tract. Using clonally-derived colonic epithelia, we show that toxins A or B of the enteric pathogen C. difficile recapitulate the salient features of pseudomembranous colitis. The stability of the epigenetic commitment programs of these stem cells, coupled with their unlimited replicative expansion and maintained clonogenicity, suggests certain advantages for their use in disease modeling and regenerative medicine.

If NFVPTCs were no longer termed carcinomas, this would affect the rate of malignancy of FNA diagnostic categories. Cytologic and molecular features could aid in identifying NFVPTCs at the time of FNA diagnosis.

Mesonephric adenocarcinoma (MA) and mesonephric-like adenocarcinoma (MLA) are uncommon neoplasms of the gynecologic tract that have until recently been poorly understood. Although their morphologic, immunohistochemical, and molecular profiles have been recently defined, little is known about their clinical behavior. Small studies have demonstrated inconsistent findings and no large studies have examined the clinical behavior of these adenocarcinomas. In this multi-institutional study, representing the largest and most stringently defined cohort of cases to date, we examined the clinicopathologic features of 99 MAs and MLAs (30 MAs of the uterine cervix, 44 MLAs of the endometrium, and 25 MLAs of the ovary). Only tumors with characteristic mesonephric morphology and either immunohistochemical or molecular support were included. Our results demonstrate that the majority of mesonephric neoplasms presented at an advanced stage (II to IV) (15/25 [60%] MA of the cervix, 25/43 [58%] MLA of the endometrium, and 7/18 [39%] MLA of the ovary). The majority (46/89 [52%] overall, 12/24 [50%] MA of the cervix, 24/41 [59%] MLA of the endometrium, and 10/24 [42%] MLA of the ovary) developed recurrences, most commonly distant (9/12 [75%] MA of the cervix, 22/24 [92%] MLA of the endometrium, and 5/9 [56%] MLA of the ovary). The 5-year disease-specific survival was 74% (n=26) for MA of cervix, 72% (n=43) for MLA of endometrium, and 71% (n=23) for MLA of ovary. Our results confirm that mesonephric neoplasms are a clinically aggressive group of gynecologic carcinomas that typically present at an advanced stage, with a predilection for pulmonary recurrence.

Background Cervical cancer is the second leading cause of cancer deaths among women worldwide. We sought to describe the most common oncogenic mutations in cervical cancers, and to explore genomic differences between the two most common histological subtypes: adenocarcinoma and squamous cell carcinoma. Methods A high-throughput genotyping platform, termed Oncomap, was used to interrogate 80 cervical tumors for 1250 known mutations in 139 cancer genes. Samples were analyzed using a mass spectrometry-based genotyping platform (Sequenom), and validated with an orthogonal chemistry. EGFR mutations were further validated by massively parallel sequencing (Illumina). Human papilloma virus (HPV) genotyping was also performed. Results Validated mutations were detected in 60.0% (48/80) of tumors examined. The highest mutation rates were PIK3CA (31.3%), KRAS (8.8%), and EGFR (3.8%). PIK3CA mutation rates were not significantly different in adenocarcinoma and squamous cell carcinomas (25.0% vs. 37.5%, respectively, p=0.33). In contrast, KRAS mutations were identified only in adenocarcinoma (17.5% vs. 0%, p=0.01), and a novel EGFR mutation was detected only in squamous cell carcinomas (0% vs. 7.5%, p=0.24). There were no associations between HPV-16 or HPV-18 and somatic mutations or overall survival. In adjusted analyses, PIK3CA mutations were associated with shorter survival—67.1 vs. 90.3 months (HR=9.1, 95% CI 2.8–29.5, p<0.001). Conclusions Cervical cancers harbor high rates of potentially targetable oncogenic mutations. In addition, cervical squamous cell carcinoma and adenocarcinoma have distinct molecular profiles, suggesting that clinical outcomes may be improved with the use of more tailored treatment strategies, including PI3-kinase and MEK inhibitors.

Mesonephric adenocarcinoma most commonly arises in the cervix and is presumed to be derived from normal or hyperplastic mesonephric remnants. It is characterized by recurrent KRAS mutations and lack of PIK3CA/PTEN alterations. Adenocarcinomas of the uterine corpus and ovary characterized by morphologic and immunophenotypic similarities to mesonephric adenocarcinoma have been reported. The pathogenesis of these tumors, which have been designated "mesonephric-like adenocarcinomas" is unknown, and it has been debated whether these represent mesonephric adenocarcinomas that arise in the endometrium/ovary or endometrioid adenocarcinomas that closely mimic mesonephric adenocarcinoma. The relationship at the molecular level between mesonephric adenocarcinomas and mesonephric-like adenocarcinomas is unknown. The aim of this study was to examine the molecular alterations in mesonephric-like adenocarcinomas to identify driver mutations and potential therapeutically targetable mutations, and to determine the relationship between mesonephric-like adenocarcinomas and mesonephric adenocarcinomas using targeted next-generation sequencing. Seven mesonephric-like adenocarcinomas (4 ovarian, 3 uterine corpus) underwent targeted next-generation sequencing to detect mutations, copy number variations and structural variants in exonic regions of 300 cancer genes, and 113 selected intronic regions across 35 genes. All 7 tumors (100%) harbored canonical activating KRAS mutations (4 G12D, 3 G12V). PIK3CA activating mutations were identified in 3 of 7 (43%) cases. There were no alterations in PTEN, ARID1A, or TP53 in any of the tumors. In copy number analysis, 5 of 7 (71%) tumors exhibited 1q gain, which was accompanied by 1p loss in 2 cases. In addition, 4 of 7 (57%) tumors had chromosome 10 gain, which was accompanied by gain of chromosome 12 in 3 cases. Mesonephric-like adenocarcinomas, similar to mesonephric adenocarcinomas, are characterized by recurrent KRAS mutations, gain of 1q, lack of PTEN mutations, and gains of chromosomes 10 and 12. PIK3CA mutations, which have not previously been identified in mesonephric adenocarcinoma, were found in 3 of 7 (43%) mesonephric-like adenocarcinomas in our study. Mesonephric-like adenocarcinomas exhibit strikingly similar molecular aberrations to mesonephric adenocarcinomas, but also frequently harbor PIK3CA mutations, demonstrating biological overlap with carcinomas of both mesonephric and Mullerian (endometrioid) differentiation. Given the previously documented association with endometriosis (ovarian neoplasms) and the prominent endometrial involvement (uterine corpus neoplasms), we believe these are best regarded as of Mullerian origin and representing adenocarcinomas which differentiate along mesonephric lines; as such, we propose the term mesonephric-like Mullerian adenocarcinoma.