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HER2 is an important prognostic and therapeutic target in uterine serous carcinoma (USC). Optimal HER2 testing platforms have not been defined and guidelines for testing have changed over time. Our objective is to assess the concordance of HER2 positivity based on chromogenic in situ hybridization (CISH), immunohistochemistry (IHC), and next generation sequencing (NGS) and to determine the rate of downstream mutations that may affect response to HER2 directed therapy.Utilizing the Caris tumor registry, 2192 USC tumors were identified and analyzed using NGS (NextSeq, 592 Genes and WES, NovaSEQ), IHC, and CISH. PD-L1 expression was tested by IHC. Microsatellite instability was tested by fragment analysis, IHC, and NGS. Tumor mutational burden (TMB) was measured by totaling somatic mutations per tumor. HER2 positivity through IHC and CISH was determined based on 2007 and 2018 ASCO/CAP HER2 breast cancer guidelines.There was a higher rate of HER2 positivity by IHC when using the 2018 guidelines compared to the 2007 guidelines (16.3% vs 12.3%). Concordance between IHC and CISH was 98.9%. ERBB2 amplification was identified by NGS in 10.5% of tumors. Compared to CISH results, this corresponds to a concordance rate of 91.6% and a positive predictive value (PPV) of 60.3%. Single gene alterations in HER2 amplified tumors that may implicate HER2 therapy resistance included PI3K (33.1%), KRAS (2.5%), and PTEN (1.3%).There was high concordance between HER2 positivity based on CISH and IHC. Rate of HER2 positivity is the lowest by NGS. Ultimately these testing platforms need to be validated by response to targeted therapy.

PTEN is known to be frequently mutated in uterine cancer and also dephosphorylates FAK. Here, we examined the impact of PTEN alterations on the response to treatment with a FAK inhibitor (GSK2256098). In vitro and in vivo therapeutic experiments were carried out using PTEN-mutated and PTEN-wild-type models of uterine cancer alone and in combination with chemotherapy. Treatment with GSK2256098 resulted in greater inhibition of pFAKY397 in PTEN-mutated (Ishikawa) than in PTEN-wild-type (Hec1A) cells. Ishikawa cells were more sensitive to GSK2256098 than the treated Hec1A cells. Ishikawa cells were transfected with a wild-type PTEN construct and pFAKY397 expression was unchanged after treatment with GSK2256098. Decreased cell viability and enhanced sensitivity to chemotherapy (paclitaxel and topotecan) in combination with GSK2256098 was observed in Ishikawa cells as compared with Hec1a cells. In the Ishikawa orthoptopic murine model, treatment with GSK2256098 resulted in lower tumor weights and fewer metastases than mice inoculated with Hec1A cells. Tumors treated with GSK2256098 had lower microvessel density (CD31), less cellular proliferation (Ki67), and higher apoptosis (TUNEL) rates in the Ishikawa model when compared with the Hec1a model. From a large cohort of evaluable patients, increased FAK and pFAKY397 expression levels were significantly related to poor overall survival. Moreover, PTEN levels were inversely related to pFAKY397 expression. These preclinical data demonstrate that PTEN-mutated uterine cancer responds better to FAK inhibition than does PTEN wild-type cancer. Therefore, PTEN could be a biomarker for predicting response to FAK-targeted therapy during clinical development. Mol Cancer Ther; 14(6); 1466–75. ©2015 AACR.

Mean mouse weights in orthotopic mouse models of uterine cancer.

Background: In contrast with the decreasing incidence seen for most cancers, endometrial cancer has been increasing in the United States. We examined whether the increasing incidence and mortality from endometrial cancer are equally distributed by race/ethnicity and tumor histologic subtype.Methods: Surveillance, Epidemiology, and End Results (SEER) endometrial cancer incidence and mortality data were obtained from 2000 to 2011. Age-adjusted incidence and incidence-based mortality rates, 95% confidence intervals, and annual percent changes (APC) were calculated. Rate ratios were calculated to compare racial/ethnic groups. Five-year relative survival rates were presented to explore survival by stage at diagnosis.Results: Incidence rates for endometrial cancers are rising across all racial/ethnic groups, with the greatest APC seen among non-Hispanic black (NHB) and Asian women (APC, 2.5 for both). NHB women have significantly higher incidence rates of aggressive endometrial cancers (clear cell, serous, high-grade endometrioid, and malignant mixed Mullerian tumors) compared with non-Hispanic white (NHW) women. Hispanic and Asian women have incidence rates equal to or lower than NHW women for all tumor subtypes. For nearly every stage and subtype, the 5-year relative survival for NHB women is significantly less than NHW women, whereas Hispanic and Asian women have the same or better survival.Conclusions: Endometrial cancer incidence is increasing for all women, particularly the aggressive subtypes. The disparity associated with excess incidence for these aggressive histologic subtypes and poorer survival is limited to NHB women.Impact: Increasing rates of aggressive endometrial cancers may widen the survival disparity between NHW and NHB women. Cancer Epidemiol Biomarkers Prev; 24(9); 1407–15. ©2015 AACR.

Supplementary Table S1: Annual percent change by subtype and race and ethnicity for endometrial cancers diagnosed 2000-2007, Surveillance, Epidemiology and End Results. Supplementary Table S2: 5 year relative survival by subtype, race and ethnicity, and stage for endometrial cancers diagnosed 2000-2007, Surveillance, Epidemiology and End Results.

Human and Mouse osteoclast precursor cells express Gal-3.

Management of bone metastasis remains clinically challenging and requires the identification of new molecular target(s) that can be therapeutically exploited to improve patient outcome. Galectin-3 (Gal-3) has been implicated as a secreted factor that alters the bone microenvironment. Proteolytic cleavage of Gal-3 may also contribute to malignant cellular behaviors, but has not been addressed in cancer metastasis. Here, we report that Gal-3 modulates the osteolytic bone tumor microenvironment in the presence of RANKL. Gal-3 was localized on the osteoclast cell surface, and its suppression by RNAi or a specific antagonist markedly inhibited osteoclast differentiation markers, including tartrate-resistant acid phosphatase, and reduced the number of mature osteoclasts. Structurally, the 158–175 amino acid sequence in the carbohydrate recognition domain (CRD) of Gal-3 was responsible for augmented osteoclastogenesis. During osteoclast maturation, Gal-3 interacted and colocalized with myosin-2A along the surface of cell–cell fusion. Pathologically, bone metastatic cancers expressed and released an intact form of Gal-3, mainly detected in breast cancer bone metastases, as well as a cleaved form, more abundant in prostate cancer bone metastases. Secreted intact Gal-3 interacted with myosin-2A, leading to osteoclastogenesis, whereas a shift to cleaved Gal-3 attenuated the enhancement in osteoclast differentiation. Thus, our studies demonstrate that Gal-3 shapes the bone tumor microenvironment through distinct roles contingent on its cleavage status, and highlight Gal-3 targeting through the CRD as a potential therapeutic strategy for mitigating osteolytic bone remodeling in the metastatic niche. Cancer Res; 76(6); 1391–402. ©2016 AACR.

Mouse osteoclast precursor expresses and secretes endogenous Gal-3.

Results of immunohistochemistry in breast and prostate cancer patients with metastasis.

Anti-CRD of Gal-3 inhibits osteoclast cell fusion.

Myosin-2A is a candidate for binding partner of Gal-3.

Gal-3 is involved in osteoclastogenesis in bone tumor microenvironment.

A noninvasive screening test would significantly facilitate early detection of epithelial ovarian cancer. This study used a combination of high-throughput selection and array-based serologic detection of many antigens indicative of the presence of cancer, thereby using the immune system as a biosensor. This high-throughput selection involved biopanning of an ovarian cancer phage display library using serum immunoglobulins from an ovarian cancer patient as bait. Protein macroarrays containing 480 of these selected antigen clones revealed 65 clones that interacted with immunoglobulins in sera from 32 ovarian cancer patients but not with sera from 25 healthy women or 14 patients having other benign or malignant gynecologic diseases. Sequence analysis data of these 65 clones revealed 62 different antigens. Among the markers, we identified some known antigens, including RCAS1, signal recognition protein-19, AHNAK-related sequence, nuclear autoantogenic sperm protein, Nijmegen breakage syndrome 1 (Nibrin), ribosomal protein L4, Homo sapiens KIAA0419 gene product, eukaryotic initiation factor 5A, and casein kinase II, as well as many previously uncharacterized antigenic gene products. Using these 65 antigens on protein microarrays, we trained neural networks on two-color fluorescent detection of serum IgG binding and found an average sensitivity and specificity of 55% and 98%, respectively. In addition, the top 6 of the most specific clones resulted in an average sensitivity and specificity of 32% and 94%, respectively. This global approach to antigenic profiling, epitomics, has applications to cancer and autoimmune diseases for diagnostic and therapeutic studies. Further work with larger panels of antigens should provide a comprehensive set of markers with sufficient sensitivity and specificity suitable for clinical testing in high-risk populations. (Cancer Res 2006; 66(2): 1181-90)

Supplementary Tables 1-4 from Diagnostic Markers of Ovarian Cancer by High-Throughput Antigen Cloning and Detection on Arrays

Materials and Methods for Tissue microarray, Immunofluorescence, Quantitative Real-Time PCR, Proteomics analysis, Co-immunoprecipitation, Co-culture.

Context.— Intraoperative consultation—frozen section diagnosis (FSD)—determines tumor pathology and guides the optimal surgical management of ovarian neoplasms intraoperatively. Objective.— To evaluate the diagnostic accuracy of the FSD and analyze the discrepancy between the FSD and final diagnosis. Design.— This is a retrospective study of 618 ovarian neoplasm FSDs from 2009 to 2018 at a tertiary health care center. The discrepant cases were reviewed and reevaluated by gynecologic and general surgical pathologists. The outcomes of interest were performing unnecessary procedure, returning for a second surgery, and 30-day postoperative mortality. Results.— The sensitivity and the positive predictive value of the FSD were lower in borderline tumors than in benign and malignant epithelial ovarian tumors. Major and minor discrepancies were identified in 5.3% (33 of 618) and 12.3% of (76 of 618) cases, respectively. A root cause analysis of the major discrepant cases showed that sampling error accounted for 43% (14 of 33). The discrepancy distributions of gynecologic and general surgical pathologists were statistically similar in the overall cohort (P = .65). The overall κ for diagnostic agreement among gynecologic pathologists, general surgical pathologists, and final diagnosis was 0.18 (0.10–0.26, P < .001), implying only a slight overall agreement. Of the major discrepant cases, only 3 had a clinical implication. One overdiagnosed patient underwent an unecessary procedure, and 2 underdiagnosed patients were recommended to return for a second surgery. No patient had 30-day postoperative mortality. Conclusions.— Frozen section diagnosis remains a definitive diagnostic tool in ovarian neoplasms and plays a crucial role in guiding intraoperative surgical management.

Background: With limited health data on Arab Americans (AAs), we sought to describe the health-seeking behaviors, prevalence of abnormal cervical cytology and high-risk human papillomavirus (HPV) serotypes, and the relationship with socioeconomic factors among a subset of AA women. Methods: Retrospective observational cohort study of women undergoing routine cancer screening at the Arab-American Center for Economic and Social Services clinic. Data collected included demographics, tobacco use, gross monthly income, prior Papanicolaou (Pap) smear history, and results of cervical cytology and high-risk HPV testing. Results: Of 430 women, 74 (17%) reported that they had never had a Pap smear. Three hundred eighty-eight (90%) women had cervical cytology interpreted as “negative for intraepithelial lesion,” the remaining 42 (10%) women had abnormal results. Thirteen (3%) women reported prior abnormal Pap smear, which was significantly associated with additional abnormal Pap smear on multivariable analyses (odds ratio 65.46; 95% confidence interval [CI] 17.01–338.62; p

To compare the frequencies of somatic homologous recombination (HR) gene mutations identified in next-generation sequencing (NGS) genomic profiling of uterine serous carcinomas (USCs) and high-grade serous ovarian carcinomas (HGSOCs).Data for this analysis was obtained from AACR Project GENIE, a multi-institutional dataset of clinical-grade NGS genomic profiling results for many cancer sites and histologic subtypes, through cBioPortal. Patient/specimen groups used for analysis were USC and HGSOC. 14 HR genes were queried for each group with respect to mutation frequency. For each HR gene, the difference in mutation frequency between the two groups was evaluated using Fisher's exact test. The threshold for statistical significance was p-value .05.In the USC group, there were 457 samples from 451 patients. In the HGSOC group, there were 1537 samples from 1515 patients. The most frequently mutated HR gene for USC was BRCA2 (4.84%) and for HGSOC was BRCA1 (9.07%). Mutation frequency was significantly different between USC and HGSOC for BRCA 1 (p .001) and BRCA2 (p = .0379). For the 12 non-BRCA HR genes, mutation frequency was not significantly different between USC and HGSOC. The rate of patients with at least one HR gene mutation in their profiled tumor was 16.85% for USC and 25.21% of HGSOC. Most USC patients with a somatic HR mutation had only one HR gene mutated.Somatic HR gene mutations were commonly identified in NGS genomic profiling of USC. Mutation frequencies for non-BRCA HR genes were not significantly different between USC and HGSOC. These data add to the growing rationale for HR deficiency tumor testing and targeting (e.g., with PARP inhibitors) in future clinical trial development for women with USC.

Context.— Metaplastic breast carcinoma is an aggressive form of breast cancer that accounts for 0.5% to 3% of all breast cancers. Objective.— To study the clinicopathologic characteristics and outcomes of this rare disease. Design.— Retrospective study of patients with a diagnosis of metaplastic breast carcinoma between 2000 and 2019. Hematoxylin-eosin–stained slides were reviewed and additional clinical data were obtained from electronic medical records. Univariable and multivariable Cox proportional hazard regression analyses were used to determine associations between overall survival and several clinicopathologic variables. Results.— Of the 125 patients with metaplastic breast carcinoma identified, only patients with high-grade disease (N = 115) were included in the data analysis. A total of 38 participants (33%) were white, 66 (57%) were African American, and 11 (10%) belonged to other ethnicities. The median age at diagnosis was 57 years. The median tumor size was 3 cm. Heterologous histology was seen in 30% of cases. Multivariable analyses showed that patients with a larger tumor size had worse overall survival (hazard ratio [HR], 1.25; 95% CI, 1.10–1.44; P < .001). Distant metastatic disease was also associated with worse overall survival on multivariable analysis (HR, 10.27; 95% CI, 2.03–55.54; P = .005). In addition to treatment with either partial or complete mastectomies, 84 patients (73%) received chemotherapy. Multivariable analyses showed that chemotherapy had no effect on overall survival (HR, 0.53; 95% CI, 0.09–6.05; P = .55). Conclusions.— A larger tumor size and distant metastatic disease are associated with worse overall survival in patients with metaplastic breast carcinoma. Additional studies are needed to further characterize our findings.

30 Background: The use of immune checkpoint inhibitors (ICI) in MSI-H/MMRd CRC patients has profoundly changed the treatment landscape in the metastatic setting; the most recent NICHE-2 trial showed 100% response rate in MSI-H/MMRd locally advanced CRC patients treated with neoadjuvant ICI, further highlighting the importance of identifying these patients accurately to enhance patient care. Here we report the concordance of NGS-MSI and IHC-MMR from a very large cohort of CRC tumors and study the molecular characteristics and clinical outcomes of these patients. Methods: A total of 28,105 CRC tumors were analyzed by NGS (592 genes, NextSeq or WES, NovaSeq) and IHC. MMRd was defined as complete loss of ≥1 IHC stains (MLH1, MSH2, MSH6, or PMS2) and proficient (MMRp) as any positive staining for all four proteins. MSI status was determined from over 7,000 target microsatellite loci covered by NGS. Central pathology review (CPR) of MMR IHC was done on 73 cases with discordant MMR/MSI results. Real-world overall survival was obtained from insurance claims and calculated from either tissue collection or treatment start to last contact; Kaplan-Meier estimates were calculated for molecularly defined patients. Results: For CRC tumors with NGS and IHC, 28031/28105 were concordant (99.74%), 0.09% were MMRd/MSS, and 0.2% were MMRp/MSI-H. After CPR, 23/24 (96%) of MMRd/MSS cases and 46/49 (94%) of MMRp/MSI-H were confirmed. Of the 46 post-CPR MMRp/MSI-H CRC samples, 52% had ≥1 pathogenic missense mutation in including MLH1/PMS2/MSH2/6 or MLH3, MSH3, PMS1 or POLE. Of the 23 post-CPR MMRd/MSS CRC samples, 38% had MLH1 loss, 91% PMS2 loss, no MSH2 loss and 9% MSH6 loss. When comparing clinical outcomes with concordant MSS/MMRp tumors, concordant MSI-H/MMRd patients had significantly longer OS (HR=1.131 [95% CI: 1.02-1.254], p28,000 CRC tumors that the concordance of IHC-MMR/NGS-MSI is 99.74%. Clinical outcome from a large cohort of patients show NGS is not inferior compared to IHC in identifying patients with MSI-H/MMRd. The additional lens that NGS-MSI offers is of value in identifying CRC patients who may benefit from ICI therapy. [Table: see text]

Background: Vaccine hesitancy is the next great barrier for public health. Arab Americans are a rapidly growing demographic in the United States with limited information on the prevalence of vaccine hesitancy. We therefore sought to study the attitudes towards the coronavirus disease 2019 (COVID-19) vaccine amongst Arab American health professionals living in the United States. Methods: This was a cross sectional study utilizing an anonymous online survey. The survey was distributed via e-mail to National Arab American Medical Association members and Arab-American Center for Economic and Social Services healthcare employees. Respondents were considered vaccine hesitant if they selected responses other than a willingness to receive the COVID-19 vaccine. Results: A total of 4000 surveys were sent via e-mail from 28 December 2020 to 31 January 2021, and 513 responses were received. The highest group of respondents were between the ages of 18–29 years and physicians constituted 48% of the respondents. On multivariable analysis, we found that respondents who had declined an influenza vaccine in the preceding 5 years (p &lt, 0.001) and allied health professionals (medical assistants, hospital administrators, case managers, researchers, scribes, pharmacists, dieticians and social workers) were more likely to be vaccine hesitant (p = 0.025). In addition, respondents earning over $150,000 US dollars annually were less likely to be vaccine hesitant and this finding was significant on multivariable analysis (p = 0.011). Conclusions: Vaccine hesitancy among health care providers could have substantial impact on vaccine attitudes of the general population, and such data may help inform vaccine advocacy efforts.

Background The current risk stratification systems used to guide management of endometrial cancer are based on irreproducible post surgical pathological information, hence the need for more reliable classification systems. Using microarray and sequencing technologies, TCGA recently identified four prognostically significant endometrial carcinoma subtypes, which subsequently proved reproducible using clinically applicable surrogate tests. Using these tests, we sought to determine the level of concordance between endometrial biopsies and subsequent hysterectomy specimens in assessing the molecular classification of endometrial carcinoma. Materials and methods Fifty biopsies with corresponding hysterectomy specimens for endometrial carcinomas were collected. Additionally, 10 cases of biopsy proven atypical hyperplasia/EIN who were found to have endometrial carcinoma on resection were included. IHC for mismatch repair (MMR) proteins (MLH1, PMS2, MSH2 and MSH6) and P53 was performed. Microsatellite instability analysis was performed by PCR and Sanger sequencing was performed to detect mutations in exons 9 and 13 of the POLE gene. The level of concordance for tumor grade, histologic subtype, immunohistochemical and molecular profile in both specimens was determined using Cohen's kappa estimates. Results A high level of concordance was achieved for MMR-loss, MSI-high, P53-wild and abnormal types. In contrast, grade and histologic subtype showed only moderate levels of agreement. POLE gene mutation was detected in two patients. For both cases, mutations were detected only in resection specimens. When comparing atypical hyperplasia/EIN with subsequent hysterectomy tumor, the profile was identical to that of endometrial carcinoma. Conclusion In our cohort of endometrial carcinoma, a high level of concordance was achieved between biopsy and hysterectomy specimens for MMR-loss, MSI-high, P53-wild and abnormal types, superior to that of grade and histologic subtype, providing earlier and more reliable prognostic information to inform management. Similar concordance could not be achieved for POLE mutation, given the low frequency of this mutation in our study.

To assess the role of serial FLT-PET scans during early neoadjuvant treatment as a prognostic marker of response to treatment and survival. This study is a prospective cohort study which draws from a larger original study which examined the utility of FLT-PET imaging across multiple cancers. Our cohort consisted of patients who had biopsy-confirmed breast cancer amenable to surgical resection. These patients underwent serial FLT-PET scans: the first scan prior to starting neoadjuvant chemotherapy (NAC), and a second scan shortly after starting NAC. SUVmean was derived using an isocontour ROI drawn approximately half way between the SUVmax and background on three planes for each scan. The change in mean standardized uptake value (SUVmean) for the primary tumor between these two scans was then calculated, and patients were stratified into “responder” and “non-responder” groups based on a cut-off of 20% arithmetic decrease in SUVmean between the two scans. The rates of pathologic complete response (pCR) on subsequent surgical excision, overall survival (OS), and progression-free survival (PFS) were then compared between the two groups to assess for significant difference between responders and non-responders. 16 patients (n = 16) met criteria for inclusion and successfully underwent FLT-PET scans in the prescribed sequence of events. Seven of these patients had a decrease of 20% or larger between the two serial PET scans, making them “responders”. The remaining nine patients were “non-responders” to NAC based on PET imaging. Between responders and non-responders, there was no significant difference in median PFS (7.9 years versus 3.7 years; p = 0.425) and median OS (7.5 years versus 5.0 years; p = 0.944). In the 14 patients who underwent surgical resection (n = 14), there was no significant difference in the rate of achieving pCR (33% vs. 14%; p = 0.5846) between responders and non-responders. Further study of a larger sample size is needed to examine the potential role for FLT-PET in predicting response to neoadjuvant treatment, particularly in correlating with long-term overall and progression-free survival. Our study is limited by small sample size, but does suggest that FLT-PET has a role in the long-term prognosis of breast cancer treated with NAC and surgical resection which is worthy of further study.

Background: Uterine serous carcinomas (USC) comprise 10-15% of all uterine cancers, but are responsible for approximately 40% of all deaths due to the disease. African American women have the highest incidence of and mortality from USC of any racial or ethnic group. Assessment of racial differences in driver mutation frequency may partially explain the survival disparity, and identification of novel alterations may provide avenues for targeted treatment. Methods: Two academic hospitals in Detroit, Michigan identified 125 women who had surgical treatment for USC and formalin fixed, paraffin-embedded tissue available for whole exome sequencing (WES). Detailed clinical and pathological data were also available, including long-term follow up. WES was performed using Illumina’s NovaSeq 6000 platform and data were processed via the Genome Analysis Toolkit (GATK), with additional filtering to account for excess artifacts resulting from formalin fixation. Functional mutations were determined by ANNOVAR and the ClinVar database, while putative driver mutations were identified via the IntOGen pipeline. Percentages were used to describe the proportion of tumors harboring a gene mutation, and the Fisher’s exact test was used to test for statistically significant differences in African American (AA) versus non-Hispanic white (NHW) mutation frequencies. Results: The majority of tumors were from AA women (n=87, 69.6%), with the remaining from NHW women (n=38, 30.4%). The overall mutational burden in tumors from AA women was similar to tumors from NHW women (median=122 and 166.5, respectively, p-value=0.12).TP53 was the most frequently mutated, with 77% of tumors from AA women and 65.8% of tumors from NHW women harboring a mutation (p-value=0.20), followed by PPP2R1A (AA=19.5%, NHW=28.9%, p-value=0.25) and PIK3CA (AA=13.8%, NHW=23.7%, p-value=0.20). Of the 66 driver genes in uterine cancer identified from IntOGen, only 3 differed significantly by race: ARID1A (AA=5.7%, NHW=28.9%; p-value=0.001), PTEN (AA=1.1%, NHW=15.8%; p-value=0.003) and FGFR2 (AA=0%, NHW=7.9%, p-value=0.02). Examination of genes with mutational frequencies ≥10% in AA or NHW tumors and with significant differences in mutation distribution by race (n=96) identified an additional 10 genes with mutations that are considered drivers in other cancer types that have not been described in uterine cancers. Conclusions: There are potential driver mutations undescribed in USC that are clinically important in other cancers. Additionally, we noted several differences in the mutation frequency by race which highlights the importance of including racially diverse samples in research, particularly AA women who have the largest burden of USC. Defining the somatic landscape of USC will lead to identification of actionable molecular targets, which will ultimately improve the prognosis of this aggressive subtype. Citation Format: Michele L. Cote, Greg Dyson, Douglas Craig, Julie J. Ruterbusch, Julie Boerner, Mohamed A. Elshaikh, Thomas P. Conrads, Nicholas W. Bateman, George L. Maxwell, Kathleen M. Darcy, Sasha Makohon-Moores, Timothy D. O'Connor, Hassan Abdallah, Logan Corey, Mira Kheil, Rouba Ali-Fehmi. Whole exome sequencing of uterine serous carcinomas reveals racial differences in known and novel driver mutations [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 750.

e17622 Background: 50% of endometrial atypical hyperplasia (AH) cases on endometrial sampling have concurrent endometrial cancer (EC) on hysterectomy. Little data exists regarding molecular signatures that can predict the presence of concurrent endometrial cancer in patients with AH on biopsy. Therefore, we set to characterize molecular landscapes of endometrial samples diagnosed with AH with EC on the final hysterectomy specimen, using matched controls. Methods: Karmanos Cancer Institute pathology database was searched for patients with AH on endometrial curettage or biopsy who had a hysterectomy within 6 months. Only samples with adequate tissue for next generation sequencing were included. In total, 59 tissue samples from 34 patients were included: there were 15 AH endometrial biopsy samples, 18 AH final hysterectomy samples (13 matched pairs), 13 EC endometrial biopsies and 13 samples that were EC on final hysterectomy samples (12 matched pairs) that were analyzed using next-generation sequencing (WES) and/or whole transcriptome sequencing (WTS) (NovaSeq). TMB was measured by counting all somatic mutations found per tumor (TMB-high: >10 mutations per MB). Immune cell infiltrates were calculated by Quantiseq. Significance was determined using Fisher exact, Chi-square and Mann-Whitney U test and adjusted for multiple comparisons: p < 0.05 but q > 0.05 was considered a trend. Results: Clinical analysis demonstrated 15/34 patients with endometrial AH on initial sampling and EC on the final hysterectomy. 2 out of 15 patients were > stage II at time of surgery. Molecularly, fewer PTEN mutations were found between AH (2/8) and EC (14/17) on final hysterectomy (25% vs 82.4%, p = 0.01). Samples of EC origin were MSI-H by NGS-MSI (3/18) and had no mutations in PPP2R1A (0/16). Comparing hysterectomy samples, EC trended toward increased CTLA4 (FC: 6.97-fold) expression and immune cell infiltration of Macrophage M1 (+1.19%), NK cells (+2.13%), CD8+ T Cells (+1.27%), regulatory T cells (+2.17%) and Dendritic cells (+2.87%) compared to AH samples (all p < 0.05). Similarly, when comparing endometrial biopsies, EC samples trended toward increased expression of CTLA4 (12.6-fold), HAVCR2/TIM3 (FC: 2.59-fold) and IFNG (FC: 17.8-fold) immune checkpoint genes, as well as increased immune cell infiltration of Neutrophils (+11.7%), CD8+ T cells (+2.39%) and regulatory T cells (+2.43%) compared to AH samples (all p < 0.05). Conclusions: There are molecular and tumor microenvironment differences seen between AH endometrial biopsies that have concurrent EC compared to those that do not on the final hysterectomy specimens. These differences may lead to advances in identifying appropriate patients for fertility sparing treatments, versus those that can be managed surgically by a benign gynecologist or a gynecologic oncologist. Analyses with larger sample sizes are needed and are ongoing.