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Background The amounts of circulating cell-free DNA (cfDNA) and circulating-tumor DNA (ctDNA) present in peripheral blood liquid biopsies can vary due to preanalytic/analytic variables. In this study, we examined the impact of patient age, sex, stage, and tumor type on cfDNA yield, ctDNA fraction, and estimated ctDNA quantity from a large cohort of clinical liquid biopsy samples. Methods We performed a retrospective analysis of 12 139 consecutive samples received for liquid biopsy (FoundationOne® Liquid) clinical testing. Results Significant differences in both cfDNA yield and estimated ctDNA quantity were observed based on the underlying tumor type that initiated the liquid biopsy analysis and the stage of the patient (P Conclusions In this study, we show that ctDNA quantity varied significantly based on patient age, sex, stage, and tumor type, which could offer an explanation as to why certain liquid biopsy specimens are more likely to fail sequencing or provide clinically meaningful results. In addition, this could affect future clinical decisions on the blood sample volumes required to allow successful liquid biopsy testing.

Objective The objective of this study was to determine the prevalence of predictive biomarkers associated with FDA-approved therapies in molecularly defined adult-type ovarian granulosa cell tumors (aGCTs). Methods We performed a retrospective cross-sectional cohort study of tumor profiles using the inclusion criteria of molecularly defined (FOXL2 c.C402G positive) aGCTs previously sequenced at Foundation Medicine, Inc. The dataset included coding variants for up to 406 genes, microsatellite instability, tumor mutational burden, and genomic loss of heterozygosity (gLOH). PD-L1 expression was determined using the tumor proportion score, as measured using the DAKO 22C3 immunohistochemistry assay. Results 423 tumor profiles met inclusion criteria. The median age at the time of sample submission was 57 years (interquartile range 48–65). The mean tumor mutational burden was 1.8 mutations per megabase (range 0–8.8). No tumors exhibited microsatellite instability, and none were gLOH-High (≥16%). Sixty-seven tumors had PD-L1 expression measurement, and 94% were negative. Potentially actionable variants including MTAP deletion (12/173, 5.8%) and activating PIK3CA mutations (23/423, 5.4%) were identified. TP53-mutated aGCT had a higher tumor mutational burden (mean 2.4 mut/Mb, 95% CI 1.7–3.0 mut/Mb vs mean 1.7 mut/Mb, 95% CI 1.5–1.9 mut/Mb; P = .02) and higher gLOH score (mean 4.4%, 95% CI 2.7–6.1% vs mean 1.4%, 95% CI 1.2–1.6%; P = .002) than TP53 non-mutated tumors. Conclusions No women with molecularly defined aGCT in this large cohort would be eligible for FDA-approved pembrolizumab based on either microsatellite instability or high tumor mutational burden. TP53 mutation identified a subset of this tumor type with distinct molecular features. The development of precision treatment options remains a critical unmet need for this rare disease.

Positive program death-ligand 1 (PD-L1) immunohistochemistry (IHC) is an approved companion diagnostic guiding the use of immune checkpoint inhibitors in uterine cervical carcinoma (CXC). The clinical and genomic features of PD-L1-positive (PD-L1positive) CXC have not been previously described. We reviewed the clinicopathologic and molecular features of 647 CXC cases that were tested using DAKO 22C3 PD-L1 IHC and comprehensive genomic profiling during the course of clinical care. PD-L1positive cases were defined via a combined positive score of ≥ 1. No differences were found in age, genetic ancestry, and HPV status of the PD-L1positive (n = 548) and PD-L1negative disease subset. The PD-L1 positivity rate varied by histologic subtype of CXC with squamous cell carcinoma (SCC) having a PD-L1 positivity rate of 91% (397/437) and usual-type adenocarcinoma’s PD-L1 positivity rate being 60% (35/58). In addition, the PD-L1 positivity rate varied depending on site of the specimen with 89.1% (261/293) positivity rate observed in cervix specimens compared to 25% (2/8) in brain metastases specimens. No significant difference in tumor mutational burden (TMB), microsatellite instability, and CD274 (encoding PD-L1) amplification was observed between PD-L1positive and PD-L1negative CXC subsets. By combining TMB with PD-L1, an additional 17 patients are eligible for pembrolizumab when compared to PD-L1 testing alone. TERT promoter alterations and APOBEC mutational signature were enriched in the PD-L1positive CXC SCC (p = 0.011, and p = 0.004, respectively). Our study reveals important prevalence data on PD-L1 positivity in CXC non-SCC and suggests that further studies in these histologic subtypes are warranted. In addition, we also provide a key framework to guide both specimen selection and future investigations of predictors of immunotherapy response in cervical cancer patients. Lastly, TERT promoter alterations and APOBEC mutational signature may be a biologically unique subset of PD-L1positive CXC SCC.

Malignant Brenner tumor is a rare primary ovarian carcinoma subtype that may present diagnostic and therapeutic conundrums. Here, we characterize the genomics of 11 malignant Brenner tumors, which represented 0.1% of 14,153 clinically advanced ovarian carcinomas submitted for genomic profiling during the course of clinical care. At the time of molecular profiling, there was no evidence of a primary urothelial carcinoma of the urinary tract in any case. Cases with transitional-like morphologic features in the setting of variant ovarian serous or endometrioid carcinoma morphology were excluded from the final cohort. Malignant Brenner tumors exhibited CDKN2A/2B loss and oncogenic FGFR1/3 genomic alterations in 55% of cases, respectively; including recurrent FGFR3 S249C or FGFR3-TACC3 fusion in 45% of cases. FGFR3-mutated cases had an associated benign or borderline Brenner tumor pre-cursor components, further confirming the diagnosis and the ovarian site of origin. Malignant Brenner tumors were microsatellite stable, had low tumor mutational burden and exhibited no evidence of homologous recombination deficiency. PIK3CA mutations were enriched with FGFR3 alterations, while FGFR3 wild-type cases featured MDM2 amplification or TP53 mutations. The FGFR3 S249C short variant mutation was absent in 14,142 non-Brenner, ovarian carcinomas subtypes. In contrast to malignant Brenner tumors, FGFR1/2/3 alterations were present in ~5% of non-Brenner, ovarian serous, clear cell and endometrioid carcinoma subtypes, most often as FGFR1 amplification in serous carcinoma or FGFR2 short variant alterations in clear cell or endometrioid carcinomas, respectively. Finally, malignant Brenner tumors had overall distinct genomic signatures compared to FGFR-mutated ovarian serous, endometrioid, and clear cell carcinoma subtypes. This study provides insights into the molecular pathogenesis of malignant Brenner tumors, contrasts the extent of FGFR1/2/3 alterations in ovarian serous, clear cell and endometrioid carcinomas and emphasizes the potential value of novel and FDA-approved, anti-FGFR inhibitors, such as erdafitinib and pemigatinib, in refractory, FGFR3-mutated malignant Brenner tumors.

PD-L1 immunohistochemistry (IHC) currently has the most Food and Drug Administration (FDA) approvals as a companion diagnostic (CDx) for immunotherapies in specific tumor types; however, multiple other immunotherapy biomarkers exist. We performed this study to examine and report the prevalence of PD-L1 expression in a wide variety of tumor types and examine its relationship to microsatellite instability (MSI), tumor mutational burden (TMB), and CD274 (PD-L1) gene amplification. We performed a retrospective analysis of all cases in which both PD-L1 IHC (using the DAKO 22C3 IHC assay with either tumor proportion score (TPS) or combined positive score (CPS); or the VENTANA SP142 assay with infiltrating immune cell score (IC)) and comprehensive genomic profiling (CGP) were tested at Foundation Medicine between January 2016 and November 2019. Of note, PD-L1 positivity is defined per the CDx indication and tumor proportion score (TPS ≥ 1) for indications without a CDx claim; and TMB positivity is defined as ≥10 mutations/Mb. A total of 48,782 cases were tested for PD-L1 IHC and CGP. Immune cell expression of PD-L1 was more frequently identified than tumor cell expression of PD-L1. We saw a high correlation between PD-L1 expression and CD274 gene amplification (p

Mullerian adenosarcoma is a biphasic neoplasm composed of benign or atypical Müllerian epithelium and a malignant mesenchymal component that is usually, but not always, of low grade. Focal architectural or cytologic atypia of the epithelial component resembling atypical hyperplasia may uncommonly be present and foci of adenocarcinoma have been rarely reported. Whether the coexistence of these 2 tumor components is a result of independent primaries (collision tumor), adenocarcinoma arising from the epithelial component of the adenosarcoma, an unusual form of carcinosarcoma or some other mechanism is uncertain. To establish the diagnostic criteria and clinical significance of the coexistence of adenocarcinoma in close association with Müllerian adenosarcoma, we conducted a multi-institutional study of these rare tumors. Twenty-six patients were identified with "mixed" adenosarcoma and adenocarcinoma; they ranged in age from 43 to 87 years (median: 66 y). Tumors occurred in the uterine corpus (n=22), ovary (n=2), and the pelvis (n=2). All but 6 had International Federation of Gynecology and Obstetrics (FIGO) stage I disease. All extrauterine tumors were associated with endometriosis. The tumor size ranged from 2 to 25 cm (median: 7.9 cm). The sarcomatous component was of low grade in 18 and high grade in 8 (the majority demonstrating rhabdomyoblastic differentiation); 9 had stromal overgrowth. Twenty-five carcinomas were endometrioid in type (23 FIGO grade 1; 3 FIGO grade 2) and 1 carcinoma was dedifferentiated with FIGO grade 1 endometrioid adenocarcinoma component; 33% of the uterine neoplasms were associated with adjacent endometrial hyperplasia. Next-generation sequencing in 2 tumors identified similar molecular abnormalities in the sarcomatous and carcinomatous components supporting a clonal relationship. Of 10 patients with available follow-up (median: 18 mo), 8 had no evidence of disease and 2 died of recurrent sarcoma at 7 and 8 months. Endometrioid adenocarcinomas that arise in close spatial association with Müllerian adenosarcoma appear to be clonally related to the sarcoma. Unlike carcinosarcomas, these tumors are usually early stage at presentation. The prognosis appears to be driven by the sarcomatous component. These tumors should be distinguished from carcinosarcomas, dedifferentiated endometrial carcinomas, and corded and hyalinized endometrioid carcinomas.

Objective Genomic alterations of BCOR via ZC3H7B-BCOR fusion or BCOR internal tandem duplication (ITD) define a subset of endometrial stromal sarcoma (ESS). The goals of this study were to: 1) determine the molecular landscape of BCOR-rearranged ESS, 2) to identify novel BCOR fusion gene partners in ESS and their associated clinicopathological characteristics, and 3) to potentially unravel targetable genomic alterations in BCOR-mutated ESS. Methods A retrospective database search of a CLIA-certified molecular laboratory was performed for uterine sarcomas that contained BCOR rearrangements or BCOR ITD. The cases were previously assayed by comprehensive genomic profiling via both DNA- and RNA-based targeted next generation sequencing during the course of clinical care. Clinicopathological and genomic data was centrally re-reviewed. Results We identify largest cohort of BCOR-rearranged ESS to date (n = 40), which included 31 cases with canonical ZC3H7B-BCOR fusion as well as 8 cases with novel BCOR gene rearrangement partners, such as BCOR-L3MBTL2, EP300-BCOR, BCOR-NUTM2G, BCOR-RALGPS1, BCOR-MAP7D2, RGAG1-BCOR, ING3-BCOR, BCOR-NUGGC, KMT2D-BCOR, CREBBP-BCOR and 1 case with BCOR internal rearrangement. Re-review of cases with novel rearrangements demonstrated sarcomas with spindle, epithelioid or small round cell components and frequent myxoid stromal change. Comprehensive genomic profiling revealed high frequency of CDK4 and MDM2 amplification in 38% and 45% of BCOR-rearranged cases, respectively, and homozygous deletion of CDKN2A, which encodes an inhibitor of CDK4 in 28% of cases. Notably, CDK4 and MDM2 amplification was absent in all cases from 15 different ESS cases harboring BCOR ITD. Conclusions Alterations of CDK4 pathway members, for which targeted therapy is clinically available (i.e. palbociclib), via CDK4 amplification or CDKN2A loss, contributes to the pathogenesis of BCOR-rearranged uterine sarcomas, which may have therapeutic implications.

Objective Small cell carcinoma of the ovary, hypercalcemic type (SCCOHT) and SMARCA4-deficient undifferentiated uterine sarcoma (SMARCA4-DUS) are rare and aggressive tumors, primarily affecting pre- and perimenopausal women. Inactivating SMARCA4 mutations are thought to be the driving molecular events in the majority of these tumors. Here, we report the clinical course of a family with germline SMARCA4 mutation and compare large cohorts of these rare tumor types. Methods We extracted clinico-pathological medical record data for the family with germline SMARCA4 mutation. Clinico-genomic data from SCCOHT and SMARCA4-DUS cohorts were retrospectively extracted from the archives of a large CLIA-certified reference molecular laboratory. Results We identified a single family with an inherited germline SMARCA4 mutation, in which two different family members developed either SCCOHT or SMARCA4-DUS, both of whom died within one year of diagnosis, despite aggressive surgical, chemotherapy and immunotherapy treatment. Retrospective comparative analysis of large SCCOHT (n = 48) and SMARCA4-DUS (n = 17) cohorts revealed that SCCOHT patients were younger (median age: 28.5 vs. 49.0) and more likely to have germline SMARCA4 alterations (37.5% vs. 11.8%) than SMARCA4-DUS patients. Conclusions Growing understanding of the role SMARCA4 plays in the pathogenesis of these rare cancers may inform recommended genetic testing and counseling in families with these tumor types.

Objective To review the genomic landscape of advanced urothelial carcinoma (UC) to assess the frequencies of EGFR and ERBB2 (HER2) alterations. Materials and methods Tumour specimens from 3753 patients with advanced UC were assayed with hybrid capture-based comprehensive genomic profiling of 180-395 genes. Tumour mutational burden (TMB) was assessed on 0.8 or 1.1 Mb of DNA, and is reported as mutations per megabase. Results In 3753 cases of UC, EGFR alterations were detected in 4.1% (154) and were most commonly amplifications (64%; 99/154), while exon 20 insertions (EGFRexon20ins ) were the second most common alteration (18%; 27/154). Alterations in ERBB2 were observed in 15% (552/3753) of cases and, similarly, ERBB2 amplification was the most commonly observed alteration (278/552; 50%); ERBB2exon20ins occurred in 3.6% (20/552) of cases. EGFRexon20ins and ERBB2exon20ins occurred in younger patients (median age 62 vs 69 years, P = 2.6E-2 and 60 vs 68 years, P = 7.8E-4), and these cases had significantly lower TMB (median 3.6 vs 7.2, P = 2.7E-4 and 2.5 vs 10, P = 1.2E-7) and less frequent TP53 alterations (3.7% vs 83%, P = 4.3E-14 and 20% vs 68%, P = 9.8E-4) compared to cases with other EGFR or ERBB2 alterations. Conclusion EGFR and ERBB2 alterations occur in 4% and 15% of UC, respectively. EGFRexon20ins and ERBB2exon20ins were present in 0.7% and 0.5% of UC overall and collectively define a small, but distinct, subset of UC with infrequent co-occurrence of other drivers and low TMB. Given recent promising clinical studies of inhibitors with activity against exon 20 insertions in non-small cell lung cancer, consideration should be given to developing a trial inclusive of patients with UC harbouring these alterations.

Although serous tubal intraepithelial carcinoma has been well described in the distal fallopian tube as precancers of pelvic high-grade serous carcinoma, endometrioid precancers have drawn less attention. Recently, endometrioid precursor lesions have been identified and reported to have a specific immunophenotype (PAX2-, ALDH1+, diffuse nuclear beta-catenin), as well as an association with both uterine and ovarian endometrioid carcinomas. These have been referred to as endometrioid (or type II) secretory cell outgrowths. A subset of endometrioid secretory cell outgrowths show architectural complexity resembling hyperplasia of the endometrium and have been referred to as endometrioid tubal intraepithelial neoplasia. We report 4 cases of endometrioid tubal intraepithelial neoplasia with clinical correlation and morphologic differential diagnosis.

Background This study assessed the contrasting genomic profiles from the primary tumors (PTs), metastatic (MET) sites, and circulating tumor DNA (ctDNA) of patients with prostate cancer (PC). Methods A total of 1294 PC tissue specimens and 2462 ctDNA specimens underwent hybrid capture-based comprehensive genomic profiling (CGP). Specimens included tissue from PTs; MET biopsies from bone, liver (LIV), lung (LU), brain (BN), lymph node, and soft tissue sites; and ctDNA. Results Differences in alteration frequencies between PT, MET, and ctDNA specimens for selected genes were observed. TMPRSS2:ERG fusion frequencies were similar between PTs and MET sites (35% vs 33%) but varied among MET sites. Genomic alterations (GAs) in AR were lowest in PTs (2%) and highest in MET sites (from 24% in LU to 50% in LIV). BN had the highest genomic alterations/tumor (8) and enrichment for PTEN GAs. The BRCA2 GA frequency varied from 0% in BN to 15% in LIV. ERBB2 amplification was increased in MET sites in comparison with PTs. RB1 GAs were increased in LIV. Biomarkers potentially associated with an anti-PD(L)1 response included CDK12 GAs (16% in LU) and a microsatellite instability-high status (29% in BN). Analyses of ctDNA featured a broad spectrum of GAs similar to those detected across MET sites. Conclusions CGP of PTs, MET sites, and ctDNA in PC exhibited differences most likely associated with tumor progression, clonal evolution, and exposure to systemic therapies; ctDNA can also capture a broad range of potential therapeutic opportunities for patients with PC.

ARIEL2 (NCT01891344) is a single-arm, open-label phase 2 study of the PARP inhibitor (PARPi) rucaparib in relapsed high-grade ovarian carcinoma. In this post hoc exploratory biomarker analysis of pre- and post-platinum ARIEL2 samples, RAD51C and RAD51D mutations and high-level BRCA1 promoter methylation predict response to rucaparib, similar to BRCA1/BRCA2 mutations. BRCA1 methylation loss may be a major cross-resistance mechanism to platinum and PARPi. Genomic scars associated with homologous recombination deficiency are irreversible, persisting even as platinum resistance develops, and therefore are predictive of rucaparib response only in platinum-sensitive disease. The RAS, AKT, and cell cycle pathways may be additional modulators of PARPi sensitivity., The identification of biomarkers of response to PARP inhibitors can enable selection of appropriate ovarian cancer patients for treatment. In this study, the authors report clinical results and exploratory biomarker analyses from the ARIEL2 phase 2 clinical trial on the safety and efficacy of the PARP inhibitor rucaparib in patients with recurrent ovarian cancers

Introduction: De-regulation of the class I phosphoinositide 3’-kinase (PI3K) pathway has long been known to contribute to the development and progression of many tumors. However, the FDA only recently approved the first selective inhibitor of PIK3CA, the p110-alpha catalytic subunit of PI3K, specifically for use in treatment of a subset of PIK3CA-mutant breast carcinomas. Given the emergence of this therapeutic class of agents, we sought to identify other subsets of breast tumors that may be driven largely by PIK3CA mutations and which therefore could be candidates for these therapies. In breast fibroepithelial neoplasms, mutations in PIK3CA have been occasionally reported in borderline and malignant phyllodes tumors. In contrast, mutations in MED12 are common and recurrent across the entire spectrum of benign and malignant breast fibroepithelial tumors, and are enriched in borderline/malignant phyllodes cases that still have benign fibroadenoma-like areas. In the current study, we sought to define the histologic and molecular features of PIK3CA-mutant phyllodes tumors. Methods: From 2014 to 2019, we analyzed clinical tumor samples using comprehensive genomic profiling by a hybrid capture-based DNA sequencing platform. We searched our case archive to find breast phyllodes tumors with known or likely pathogenic alterations in PIK3CA and other known tumor-related genes. All cases were clinically advanced. We reviewed pathology reports, histopathology, and patient clinical data. Results: We identified 12 (16%) of 76 breast phyllodes tumors in our case archive as PIK3CA-mutant. Median patient age for PIK3CA-mutant phyllodes tumors was 56 years. Cases consisted of 6 primary tumors, 2 local recurrences, and 4 lung metastases. Primary tumor size measured from 38 to 220 mm (median 100 mm; mean 114 mm). Digital slides were available for histology review in 9 cases. Cases showed uniformly malignant histology, with no benign or fibroadenoma-like regions. 3 cases showed malignant heterologous elements. Compared to the rest of our breast phyllodes tumor cohort, PIK3CA-mutant cases showed significantly fewer pathogenic genomic alterations in MED12 (8% vs. 55%, p=0.0037) and TP53 (17% vs. 56%, p=0.0245), as well as a trend to fewer mutations in RB1 (0% vs. 22%, p=0.11). The other most frequently mutated genes in the PIK3CA-mutant group were TERTp (70%), CDKN2A (67%), and NF1 (50%). Conclusions: PIK3CA-mutant phyllodes tumors define a unique subset of tumors characterized by aggressive histologic features and largely lacking the MED12 mutations seen in many fibroepithelial neoplasms. These findings provide compelling rationale for comprehensive genomic profiling of advanced cases of this disease in an effort to inform therapeutic options including clinical trials of PI3K-targeted agents in this setting. Citation Format: Erik A Williams, Ethan S Sokol, Dean C Pavlick, Nikunj Shah, Julia A Elvin, Jo-Anne Vergilio, Jonathan K Killian, Nhu Ngo, Douglas Lin, Vincent A Miller, Jeffrey S Ross. PIK3CA-mutant breast phyllodes tumors show a uniformly aggressive histology and significant mutual exclusivity with MED12 mutation [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P4-06-07.

Summary The sarcomatoid variant of renal cell carcinoma is a highly aggressive tumor with propensity for metastasis and limited therapeutic options. Metastases of sarcomatoid renal cell carcinoma can sometimes be mistaken for a variety of spindle cell sarcomas, particularly at soft tissue sites in the absence of a history of a kidney tumor. Immunoreactivity for markers associated with certain types of soft tissue sarcomas can, therefore, pose a pitfall for diagnosis under such circumstances. We evaluated the immunohistochemical and molecular features of 49 cases of sarcomatoid renal cell carcinoma with special emphasis on the expression of MDM2 by immunohistochemistry and MDM2 amplification by fluorescence in situ hybridization. Of the 49 sarcomatoid renal cell carcinoma cases evaluated by fluorescence in situ hybridization, 5 (10%) were positive for MDM2 gene amplification and 5 (10%) contained polysomy 12. Immunohistochemical nuclear expression for MDM2 was also observed in 30/49 (61%) cases; of these, 15/19 (78%) were metastatic and 15/30 (50%) were primary. MDM2 expression by immunohistochemistry has been previously reported in conventional clear cell renal cell carcinoma; however, occurrence of this phenomenon has not yet been properly assessed in the sarcomatoid variant of renal cell carcinoma. Our study demonstrates that alterations of the MDM2 pathway are relatively frequent in sarcomatoid renal cell carcinoma, and nuclear positivity for MDM2 by immunohistochemistry, as well as MDM2 amplification by fluorescence in situ hybridization may pose a potential pitfall for diagnosis with dedifferentiated liposarcoma at metastatic sites. A panel approach to immunohistochemical testing is recommended for the diagnosis of these lesions. Also, identification of cases of sarcomatoid renal cell carcinomas harboring MDM2 copy number gain or gene amplification may also have potential therapeutic implications.

Comprehensive genomic profiling (CGP) and immunohistochemistry (IHC) are important biomarker tools used for patients with non-small cell lung cancer (NSCLC) given the expanding number of standard-of-care therapies that require companion diagnostic testing. We examined 9450 NSCLC real-world patient samples that underwent both CGP and programmed death-ligand 1 (PD-L1) IHC to understand the biomarker landscape in this patient cohort. By assessing National Comprehensive Cancer Network (NCCN)-recommended biomarkers including genomic alterations, tumor mutational burden (≥10 mutations/Mb cut-off), and PD-L1 expression (Tumor Proportion Score (TPS) ≥ 50% cut-off), we show that CGP + PD-L1 IHC yielded potentially actionable results for 70.5% of the 9,450 patients with NSCLC. Among the remaining 29.5% (2,789/9,450) of patients, 86.7% (2,419/2,789) were potentially eligible for another biomarker-associated therapy and/or clinical trial based on their genomic profile. In addition, in the PD-L1TPS≥50% disease subset, BRAF mutations, MET mutations, MET amplifications, and KRAS mutations were significantly enriched; and in the PD-L1TPS, EGFR mutations, ERBB2 mutations, STK11 mutations, and KEAP1 mutations were enriched. These findings highlight the improved clinical utility of combining CGP with IHC to expand the biomarker-guided therapeutic options available for patients with NSCLC, relative to single biomarker testing alone.

Introduction Pembrolizumab was approved with an accompanying companion diagnostic (CDx) assay (PD-L1 DAKO 22C3) for urothelial carcinoma (UC). In this study, we further characterize the clinicopathologic and genomic features of UC that are programmed death-ligand 1 (PD-L1) positive. Materials and Methods The cohort of this study consisted of a total of 528 consecutive UC patients with PD-L1 immunohistochemistry (IHC) and comprehensive genomic profiling (CGP). All PD-L1 IHC testing was performed using the DAKO 22C3 CDx assay for UC. PD-L1 positivity was determined at a combined positive score ≥ 10. Results A total of 44.5% (235/528) patients with UC were PD-L1positive. A lower PD-L1 positivity rate was detected in primary (42.3%, 148/350) versus metastatic sites (48.9%, 87/178). PD-L1 positivity was dependent on the location of the metastatic sites. CGP revealed PD-L1positive patients had more frequent genomic alterations (GAs) in TP53 (p = .006) and RB1 (p = .003) and less frequent GAs in FGFR3 (p = .001) and MTAP (p = .028). The APOBEC mutational signature and tumor mutational burden (TMB)-high were more common in PD-L1positive patients. By testing patients with UC with CGP, in addition to PD-L1 IHC, an additional 97 patients (18.4%) in the total cohort were eligible for immunotherapy based on TMB status. Conclusion PD-L1positive and PD-L1negative urothelial carcinomas are genomically different. Also, our study provides the framework for future clinical investigation with regard to specimen site selection for PD-L1 testing as well as candidate biomarker genomic alterations that may predict for better response or lack of response to immune checkpoint inhibitors. Implications for Practice In this study, a higher prevalence of TP53 and RB1 alterations and APOBEC mutational signatures in the PD-L1positive urothelial carcinoma disease subset and enrichment of FGFR3 alterations in the PD-L1negative disease subset were found. These data provide the basis for future investigation into the role of these genomic changes as positive and negative predictors of immunotherapy response. Also, differences wer seen in PD-L1 positivity based on the collection site of the sample, which can provide a framework for future clinical trial design and could influence sample selection for PD-L1 testing in patients with urothelial carcinoma when multiple samples are available.

Highlights • Gastric type endocervical adenocarcinoma (GAS) is rare in the United States. • GAS is an aggressive tumor and can metastasize unusual sites including peritoneal surfaces and adnexa. • Metastatic lesions can mimic benign/borderline mucinous tumors of ovaries. • There is no established standard of care for GAS. • Genetic consultation should be included in patient’s management.

Despite advances in systemic therapies for solid tumors, the development of brain metastases remains a significant contributor to overall cancer mortality and requires improved methods for diagnosing and treating these lesions. Similarly, the prognosis for malignant primary brain tumors remains poor with little improvement in overall survival over the last several decades. In both primary and metastatic central nervous system (CNS) tumors, the challenge from a clinical perspective centers on detecting CNS dissemination early and understanding how CNS lesions differ from the primary tumor, in order to determine potential treatment strategies. Acquiring tissue from CNS tumors has historically been accomplished through invasive neurosurgical procedures, which restricts the number of patients to those who can safely undergo a surgical procedure, and for which such interventions will add meaningful value to the care of the patient. In this review we discuss the potential of analyzing cell free DNA shed from tumor cells that is contained within the cerebrospinal fluid (CSF) as a sensitive and minimally invasive method to detect and characterize primary and metastatic tumors in the CNS.

PurposeLeiomyosarcomas (LMS) harbor frequent inactivation of TP53 and RB1, and extensive DNA copy number alterations. Here, we describe a distinct recurrent genomic signature in TP53/RB1-wildtype uterine LMS.MethodsTissues from 276,645 unique advanced cancers, including 2,570 uterine and soft tissue LMS were sequenced by hybrid-capture-based next-generation DNA and RNA sequencing/comprehensive genomic profiling of up to 406 genes. We characterized clinicopathologic features of relevant cases.ResultsWe identified 77 LMS with homozygous copy loss of CDKN2C at chromosome 1p32.3 (3.0% of LMS). Genomic alterations (GAs) in TP53, RB1, and ATRX were rare in comparison with the remainder of the LMS cohort (11.7% vs 73.4%, 0% vs 54.5%, 2.6% vs 24.5%, all pCDKN2C-null LMS cases were significantly enriched for GAs in CIC (40.3% vs 1.4%) at 19q13.2, CDKN2A (46.8% vs 7.0%), and RAD51B (16.9% vs 1.7%; all pCDKN2C-null LMS cases exhibited 1p/19q-codeletion, with significant enrichment in comparison to the remainder of the evaluated LMS cohort (85% vs. 5.1%, p99% of CDKN2C-null cases were in females; median age was 61 years at surgery (range, 36-81 years). 55 cases were of uterine primary, 4 cases non-uterine, and the remaining 18 of uncertain primary site. 6 patients had a prior history of leiomyomatosis or uterine smooth muscle tumor of uncertain malignant potential. 60% of cases showed at least focal epithelioid variant histology. Most cases were of known advanced stage, with 62% of confirmed uterine primary cases at FIGO stage IVB.ConclusionThe identification of this novel genomic subset may have prognostic and/or therapeutic clinical relevance, including use of specific cyclin-dependent kinase inhibitors.

BackgroundImmune checkpoint inhibitors (ICIs) benefit patients with multiple cancer types, however, additional predictive biomarkers of response are needed. CD274 (programmed cell death ligand-1, PD-L1) gene rearrangements are positively associated with PD-L1 expression and may confer benefit to ICI, thus a pan-cancer characterization of these alterations is needed.MethodsWe analyzed 283,050 patient samples across multiple tumor types that underwent comprehensive genomic profiling for activating CD274 rearrangements and other alterations. The DAKO 22C3 Tumor Proportion Scoring (TPS) method was used for PD-L1 immunohistochemistry (IHC) testing in a small subset with available data (n=55,423). A retrospective deidentified real-world clinico-genomic database (CGDB) was examined for ICI treatment outcomes. We also report a detailed case of CD274-rearranged metastatic rectal adenocarcinoma.ResultsWe identified 145 samples with functional rearrangements in CD274. There were significant enrichments for PIK3CA, JAK2, PDCD1LG2, CREBBP, and PBRM1 co-mutations (ORs=2.1, 16.7, 17.8, 3.6, and 3.4, respectively, pCD274 wild-type samples (7.0 vs 3.5 mutations/Mb, p=1.7e-11), with disease-specific TMB enrichment in non-small cell lung, colorectal, unknown primary, and stomach cancers. PD-L1 IHC skewed toward positivity (N=39/43 samples with ≥1% positivity). Of eight patients from the CGDB, three remained on ICI treatment after 6 months. Separately, one patient with metastatic rectal adenocarcinoma experienced a pathologic complete response on chemoimmunotherapy.ConclusionsCD274 gene rearrangements are associated with increased PD-L1 IHC scores, higher TMB, and potential clinical benefit in ICI-treated patients with cancer.

Background Carcinoma of the urethra (UrthCa) is an uncommon Genitourinary (GU) malignancy that can progress to advanced metastatic disease. Methods One hundred twenty-seven metastatic UrthCa underwent hybrid capture-based comprehensive genomic profiling to evaluate all classes of genomic alterations (GA). Tumor mutational burden was determined on up to 1.1 Mbp of sequenced DNA, and microsatellite instability was determined on 114 loci. PD-L1 expression was determined by IHC (Dako 22C3). Results Forty-nine (39%) urothelial (UrthUC), 31 (24%) squamous (UrthSCC), 24 (19%) adenocarcinomas NOS (UrthAC), and 12 (9%) clear cell (UrthCC) were evaluated. UrthUC and UrthSCC are more common in men; UrthAC and UrthCC are more common in women. Ages were similar in all 4 groups. GA in PIK3CA were the most frequent potentially targetable GA; mTOR pathway GA in PTEN were also identified. GA in other potentially targetable genes were also identified including ERBB2 (6% in UrthUC, 3% in UrthSCC, and 12% in UrthAC), FGFR1-3 (3% in UrthSCC), BRAF (3% in UrthAC), PTCH1 (8% in UrthCC), and MET (8% in UrthCC). Possibly reflecting their higher GA/tumor status, potential for immunotherapy benefit associated with higher tumor mutational burden and PD-L1 staining levels were seen in UrthUC and UrthSCC compared to UrthAC and UrthCC. Microsatellite instability high status was absent throughout. Conclusions Comprehensive genomic profiling reveals GA that may be predictive of both targeted and immunotherapy benefit in patients with advanced UrthCa and that could potentially be used in future adjuvant, neoadjuvant, and metastatic disease trials.

Objectives: Endometrial serous carcinoma (EMSC) is an aggressive variant of uterine cancer with limited therapeutic options. We analyzed the genomics of the largest EMSC cohort to date (n=2,159) to determine the extent of homologous recombination deficiency (HRD) and potential for targeted therapies. Methods: EMSC was assayed via hybrid capture-based comprehensive genomic profiling. HRD status was determined using genome wide loss of heterozygosity (gLOH) scores with validated methods for PARP inhibitor effectiveness in ovarian carcinoma. gLOH-high was defined as a score of ≥16%, similar to previously described for ovarian carcinomas. Tumor mutational burden (TMB) was determined on 0.8Mbp of sequenced DNA, and TMB-high was defined as ≥10mut/Mb using an FDA-approved companion diagnostic cutoff for pembrolizumab in patients with unresectable or metastatic solid tumor based on the KEYNOTE-158 trial. Microsatellite instability (MSI) was determined on 95 loci. Clinicopathological and genomic data was centrally re-reviewed. Results: EMSC is characterized by TP53 mutations (92%), microsatellite stability (99%), low tumor mutational burden (96%), and less frequent recurrent alterations in PIK3CA (35%), PPP2R1A (25%), CCNE1 (19%), ERBB2 (17%), FBXW7 (17%) and MYC (12%). Evidence for HRD via high gLOH was identified in 21% of EMSC. There was no difference in age, MSI and TMB-high status between gLOH-high vs gLOH-low EMSC. However, alterations in BRCA1/2 and HRD genes as a group were significantly enriched in gLOH-high EMSC (14% vs 2% and 23% vs 9%, both p Conclusions: EMSC has overall distinct genomic signatures compared to endometrioid endometrial carcinomas with a significant proportion of gLOH-high EMSC, compatible with HRD. Our study provides the framework for future studies to test the susceptibility of EMSC to PARP inhibitor therapy in a molecularly defined EMSC subgroup with evidence for HRD.

Objectives: Recently, TMB ≥10 tumor mutational burden-high (TMB-high)mutations/megabase (mut/Mb) was approved as a companion diagnostic for pembrolizumab in patients with unresectable or metastatic solid tumor based on the KEYNOTE-158 trial. This approval offers patients with gynecologic tumors another pathway to pursue eligibility for immune checkpoint inhibitors (ICPI). Here, we present the real-world prevalence of TMB-High in a large cohort of gynecologic tumors and examine its correlation to other ICPI biomarkers. Methods: We retrospectively reviewed 17,304 gynecologic tumors tested with comprehensive genomic profiling (CGP). TMB was determined on 0.79 Mb of sequenced DNA, microsatellite instability (MSI) was assessed across 95 loci, and CD274 amplification was defined copy number ≥ ploidy + 4. For a subset of cases, PD-L1 immunohistochemistry was performed concurrently on the samples with DAKO 22C3 assay and scored with a combined positive score (CPS) or a tumor proportion score (TPS). For cervical carcinoma, a CPS ≥ 1 was considered positive and for non-cervical carcinoma, a TPS ≥ 1 was considered positive. Results: TMB-High frequencies varied amongst the different types of gynecologic tumors, with TMB-High occurring more frequently in vaginal carcinoma, uterine carcinoma, and cervical carcinoma (27.5%, 22.1%, and 21.4%, respectively) and less frequently in vulvar carcinoma, ovarian carcinoma, fallopian tube carcinoma, and peritoneum carcinoma (10.0%, 4.0%, 3.5%, 2.0%, respectively). MSI-High was highly correlated with TMB-High, although a small subset of MSI-High was present in the cervical carcinoma and uterine carcinoma TMB Download : Download high-res image (190KB) Download : Download full-size image Conclusions: TMB-High is common in many types of gynecologic tumors and can identify additional patients that may be eligible for ICPI that are not identified by MSI, PD-L1, and CD274 amplification ICPI biomarkers. In addition, potential resistance and hyper-progression biomarkers were present in most gynecologic tumor TMB disease subsets. These results highlight that CGP should be considered for all gynecologic tumors in order to evaluate TMB, identify POLE-hypermutated carcinomas, and to determine eligibility for ICPI.

Objectives: Among women with high-risk human papillomavirus (hrHPV) detected in cervical swabs, the distribution of hrHPV types is known to differ by racial/ethnic group, with East and West Africans and North Americans of African ancestry1 showing overrepresentation of hrHPV types that are not covered by the current 9-valent HPV vaccine. Possible downstream consequences in ethno-specific rates of aggressive hrHPV-related cancers, however, have not been systematically examined. Here, we surveyed a large, multiethnic database of aggressive cancers for non-9-valent-vaccine hrHPV types in association with individual ancestry data. Download : Download high-res image (398KB) Download : Download full-size image Methods: Our archive of 290,311 unique advanced cancer samples underwent comprehensive genomic profiling (CGP) using a hybrid-capture-based DNA sequencing platform. We detected hrHPV genomic sequences in 1,690 cervical, 1,196 anogenital, and 1,380 head and neck cancers by de novo assembly of nonhuman reads, followed by alignment to the RefSeq database, which distinguishes hrHPV types. Patient ancestry was determined by classifying specific SNPs by CGP based on their known variation among populations in the 1000 Genomes Project. Quantitative data were analyzed using the Fisher exact test. A two-tailed P value of Results: We identified four non-vaccine hrHPV types with >10 cancer cases each: HPV35 (n=71 cases), HPV51 (n=11), HPV59 (n=42), and HPV67 (n=12). Among patients whose cancers harbored hrHPV types that are covered by the 9-valent vaccine (here, HPV16, 18, 31, 33, 45, 52, and 58), 7.5% (308/4,131) were of African ancestry, lower than the overall representation of African ancestry in our database (9.1% [26,471/290,311]). In contrast, among cases with non-9-valent-vaccine hrHPV types, we identified several-fold enrichment for individuals of African ancestry (HPV35: 24% of African ancestry [17/71], HPV51: 27% [3/11], HPV59: 43% [18/42], HPV67: 25% [3/12]). In total, these four non-vaccine hrHPV types accounted for 11.4% (40/350) of all hrHPV-related advanced cancers in persons of African ancestry, but only 2.4% (95/3928) of hrHPV-related advanced cancers in individuals of other ancestries, a difference of nearly five-fold (p Conclusions: In our pan-hrHPV analysis of advanced cancers, hrHPV types not covered by the current 9-valent vaccine are strikingly increased in individuals of African ancestry. Our data strongly indicate a need to re-evaluate the choice of hrHPV types to include in the vaccine, as well as a need to re-evaluate the underlying process by which hrHPV types are chosen for inclusion.

Objectives: Analysis of circulating tumor DNA (ctDNA) extracted from peripheral blood liquid biopsies is a less-invasive alternative to traditional solid tumor tissue testing. In this study, we analyzed a large cohort of liquid biopsies collected from advanced tubo-ovarian and peritoneal cancer patients to determine the clinical utility and landscape of potentially actionable genomic alterations. Methods: CGP by a hybrid-capture based sequencing assay was performed on blood samples from 574 patients with primary ovarian, fallopian tube, or peritoneal cancer. Short variant alterations, rearrangements, and copy number gains were interrogated across exons from 70 genes and introns from 7 genes; gene deletions were not evaluated. Microsatellite instability (MSI) was also assessed by the assay. An additional cohort assayed by an expanded gene panel and an analysis of paired liquid and tissue samples will be presented. Results: A total of 527 ovarian primary, 36 fallopian tube primary, and 11 peritoneal primary cancers were analyzed. Patients had a median age of 68 years (range 22-89+). There were 202 serous carcinomas, 7 carcinosarcomas, 7 clear cell carcinomas, 6 endometrioid carcinomas, 4 mucinous carcinomas, 1 carcinoma of mixed histology, and the remainder of the cases (n=347) had no specified histologic subtype. A total of 508 (89%) patients had at least 1 genomic alteration detected by the assay. The most frequently altered genes were TP53 (74%) consistent with high-grade carcinomas, CHEK2 (24%), ATM (14%), BRCA1 (7%), NF1 (7%), PIK3CA (6%), BRCA2 (5%), and KRAS (5%). Patients often harbored more than one alteration in TP53, CHEK2, and ATM (48%, 22%, and 16% of altered cases respectively). Alterations in BRCA1/2 were detected in a total of 71 patients (12.3%). 8/71 cases (11.3%) had multiple alterations in either BRCA1 or BRCA2, and these alterations were consistent with known reversion mechanisms that restored BRCA1/2 function and conferred resistance to PARP inhibitors (PARPi). Follow-up was available for one of these patients, who had BRCA2 alterations and had received 10 months of PARPi therapy prior to the collection of their liquid biopsy. A second patient showed acquisition of a second, likely reversion BRCA1 alteration on their liquid biopsy from a solid-tissue CGP test performed 22 months prior. Rearrangements in genes associated with approved targeted therapies were detected in FGFR2 (n=3), RET (n=1), ROS1 (n=1), and ALK (n=1). Other potentially targetable genes altered in this cohort included ERBB2 (1%), BRAF (1%), and PALB2 (1%). Additionally, one case was found to be MSI-high. Conclusions: CGP via liquid biopsies identified actionable alterations in metastatic or recurrent ovarian, fallopian tube, and peritoneal carcinomas across various histologic subtypes. The mutational landscape included alterations that supported the tissue diagnosis as well as potentially targetable alterations by both FDA-approved and investigational agents in clinical trials, inlcuding BRCA1/2 mutations that conferred sensitivity and/or explained resistance to PARPi therapy. These results support the clinical utility and integration of liquid biopsy in guiding the treatment of advanced tubo-ovarian and peritoneal cancers.

5062 Background: Loss-of-function genomic alterations (GAs) in MSH6 have been associated with a unique subtype of hypermutated mCRPC that is often microsatellite stable (MSS) and may occur in either a sporadic or familial Lynch Syndrome-like clinical setting. Methods: 5,617 mCRPC cases were sequenced to evaluate all classes of GA using a hybrid capture-based FDA-approved comprehensive genomic profiling (CGP) assay. Tumor mutational burden (TMB) was determined on 0.8 Mb of sequenced DNA and microsatellite instability high (MSI-High) was determined on 95 loci. MSI-low status was not assessed. Results: 78 (1.4%) mCRPC were MSH6mut (Table). MSH6mut mCRPC included 73.1% short variant mutations, 23.1% biallelic deletions, 2.6% genomic rearrangements, and 1.3% multiple GAs/sample. Co-mutation of MSH2 was found in 28% of MSH6mut cases vs. 2% in MSH6wt cases (P mut mCRPC, which was significantly greater than the 2% seen in MSH6wt cases (P mut cases, compared to 3% MSH6wt cases (P mut cases with neither MSI-High nor MMR mutational signature, 87% did not have biallelic loss of MSH6 or any other MMR gene, confirming that monoallelic pathogenic mutations are insufficient to cause the MMR-D phenotype. For subjects whose variants could be classified, 45% (19/42) of pathogenic MSH6 alleles were germline; of these, 58% (11/19) had neither MSI-High nor an MMR single nucleotide signature. MSH6mut cases had fewer TMPRSS2: ERG fusions (P =.01), but harbored significantly higher frequencies of GAs in AR (P =.0002), ATM (P =.04), PIK3CA (P =.0003), APC (P =.005), ERBB2 (P =.001), and CDK6 (p =.046), likely at least partially attributable to the higher TMB in MSH6mutcases (P mut mCRPC is a unique disease that often features a hypermutated genomic signature, although only 46% of cases exhibited MSI-high status. This complex phenotype highlights the potential utility of multiple rather than single biomarkers to understand tumor biology and determine patients who may benefit from immunotherapy.[Table: see text]

8555 Background: Malignant pleural mesothelioma (MPM) is an aggressive malignancy with limited therapeutic options. Immunotherapy has emerged as an effective therapeutic strategy, particularly in the non-epithelioid MPM subgroup. An improved understanding of the molecular profile of MPM may inform targeted therapeutic approaches and provide insights into factors underlying differential sensitivity to therapies. Methods: We performed comprehensive genomic profiling of MPMs from 980 patients, with histologic subtyping on a subset (n = 340; n = 235 epithelioid, n = 48 sarcomatoid, n = 57 biphasic). Analyses included quantifying tumor mutational burden (TMB), assessing microsatellite instability (MSI), and evaluating PD-L1 expression (Dako 22C3). Results: Median TMB of MPM was 1.74 (0.87-2.61) mutations per megabase (mut/mb). Median TMB was comparable for non-epithelioid (biphasic, sarcomatoid) vs epithelioid MPM (1.25 mut/mb vs 1.25 mut/mb, p = 0.43). In the overall cohort, inactivating alterations in the following genes were most prevalent: CDKN2A (49%), BAP1 (44%), CDKN2B (42%), MTAP (35%), and NF2 (33%). MTAP loss co-occurred with CDKN2A and CDKN2B loss in > 99% and 94% of cases, respectively. MTAP loss was observed in 28% of epithelioid vs 46% of non-epithelioid MPMs (p = 0.03). BAP1 alterations were detected in 51% of epithelioid vs 36% of non-epithelioid MPMs (p = 0.81). PD-L1 expression was assessed in 308 MPMs, among which 153 (49%) had PD-L1 ≥1%, including 35 (11%) with PD-L1 ≥50%. Among 164 specimens that underwent histologic subtyping and PD-L1 evaluation, PD-L1 was expressed in 46 (71%) non-epithelioid MPMs compared to 49 (51%) epithelioid MPMs (p = 0.03). Given the high prevalence of alterations involving the two genes, we evaluated impact of BAP1 and MTAP status on PD-L1 and TMB. TMB (1.74 mut/mb vs 1.74 mut/mb) and PD-L1 expression (50% vs 54%) were comparable in BAP1-altered vs wildtype specimens. Although TMB was comparable in MTAP-deficient and MTAP-intact tumors (1.25 mut/mb vs 1.74 mut/mb), more tumors with MTAP loss expressed PD-L1 (68% vs 44%, p = 0.0004). Conclusions: Compared to epithelioid MPM, non-epithelioid tumors demonstrate comparable TMB, higher PD-L1 expression, and enrichment for MTAP loss. As MTAP is frequently altered in MPM, further study is indicated to explore the relationship between MTAP status and MPM biology, including sensitivity to therapeutics such as immunotherapy and synthetic lethal approaches.

5567 Background: The FDA has separately approved pembrolizumab for all advanced solid tumors with either microsatellite instability or high tumor mutational burden (≥10 mutations per megabase), and homologous recombination deficiency is an established biomarker for response to poly ADP ribose polymerase inhibitors in epithelial ovarian cancer. The detection of these predictive biomarkers in adult-type ovarian granulosa cell tumors could identify novel treatment strategies in this rare disease. The primary objective of this study was to determine the prevalence of established predictive biomarkers among molecularly defined adult-type ovarian granulosa cell tumors. Methods: With institutional review board approval, we performed a cross-sectional study examining de-identified FoundationOne companion diagnostic molecular profiles for 423 women with molecularly defined (FOXL2 c.C402G positive) adult type ovarian granulosa cell tumors. The dataset was comprised of coding variants for up to 406 genes as well as genomic signatures including microsatellite instability, tumor mutational burden, and genome wide loss of heterozygosity. PD-L1 expression by immunohistochemistry was also available for a subset of tumors. Descriptive statistics were used for comparison between groups and all statistical tests were two-sided. Results: Women in this cohort had a mean age of 57 years (range 24-87) at the time of sample submission for molecular profiling. The median tumor mutational burden was 1.3 mutations per megabase [mut/Mb] (range 0-8.8 mut/Mb). TP53-mutated aGCT had a higher tumor mutation burden than TP53 non-mutated tumors (median 2.4 mut/Mb, 95% CI 1.7-3.0 mut/Mb vs median 1.3 mut/Mb, 95% CI 1.5-1.9 mut/Mb; P=.02). All 384 tumors with available microsatellite instability testing were microsatellite stable. Sixty-seven tumors had PD-L1 expression measured and of these 94% (63/67) were negative with the remainder “low positive.” No tumors were positive for genome wide loss of heterozygosity. Apart from FOXL2 c.C402G, the most frequent short variants were TERT promoter mutations (-124C>T: 190/423, 45.0%; -146C>T: 39/423, 9.2%). Other frequently observed variants included truncating mutations in KMT2D/MLL2 (71/423, 16.8%), pathogenic TP53 mutations (35/423, 8.3%), CDKN2A/B deletions (43/423, 10.2%), and activating PIK3CA mutations (23/423, 5.4%). Conclusions: No women with molecularly defined adult-type ovarian granulosa cell tumors in this large cross-sectional study would be eligible for FDA-approved pembrolizumab based on either microsatellite instability or high tumor mutational burden. No tumors exhibited evidence of homologous recombination deficiency and molecularly targetable mutations were rare. The development of novel precision treatment options remains a critical unmet need for this rare disease.

3130 Background: Given that the clinical manifestations, disease course, and treatment options for pSCC differ between tumor types, we performed CGP to examine possible genomic differences. Methods: 1,741 clinically advanced pSCCs including 230 penile (penSCC), 17 male urethral (murthSCC), 125 male anal (manSCC), 7 female urethral (furthSCC), 263 vulvar (vulSCC), 822 cervical (crvSCC), and 277 female anal SCCs (fanSCC) underwent hybrid capture-based CGP to evaluate all classes of genomic alterations (GAs). Tumor mutational burden (TMB) was determined on up to 1.1 Mb of sequenced DNA and microsatellite instability (MSI) was determined on up to 114 loci. PD-L1 expression was determined by IHC (Dako 22C3). Results: HPV-16/18 detection was lowest in murthSCC and vulSCC and highest in manSCC, fanSCC, and crvSCC. TP53 GAs were inversely associated with HPV status. PIK3CA GA frequency varied (22-43%). DNA-damage response (DDR) GAs (e.g., BRCA1/2, ATM, others) were low ( < 1-3%) throughout. Cell-cycle GAs were most frequent in external cases (penSCC, furthSCC, vulSCC). MTOR pathway GAs ( PTEN, FBXW7) were the most frequently identified “actionable” GAs. FGFR3 GA were present in >5% of murthSCC, crvSCC, and fanSCC; other receptor-tyrosine kinase (RTK) targeted options were 1% in BRAF/ ERBB2. NOTCH1 GAs were present in > 15% of penSCC and vulvSCC. TMB ≥10 mut/Mb was >15% in manSCC, fanSCC, and crvSCC. PD-L1 low expression was > 25% in all pSCC except crvSCC and high expression was > 18% in all pSCC except urthSCC and manSCC. Conclusions: Despite similar histology, pSCC differ widely in GAs and HPV status. PIK3CA is the most frequent “targetable” GA followed by MTOR pathway and cell cycle; RTK targets are extremely rare. PARP inhibitor options appear low given the infrequent finding of DDR GAs. Anti-PD(L)1 could be considered in a number of cases based on TMB>10 mut/Mb and PD-L1 expression.[Table: see text]

This cross-sectional study assesses the prevalence of high-risk human papillomavirus (hrHPV) types not covered by the 9-valent HPV vaccine among patients of African vs non-African ancestry with advanced squamous cell carcinoma.

High-grade serous ovarian carcinoma (HGSOC) is the most frequent type of ovarian cancer and has a poor outcome. It has been proposed that fallopian tube cancers may be precursors of HGSOC but evolutionary evidence for this hypothesis has been limited. Here, we perform whole-exome sequence and copy number analyses of laser capture microdissected fallopian tube lesions (p53 signatures, serous tubal intraepithelial carcinomas (STICs), and fallopian tube carcinomas), ovarian cancers, and metastases from nine patients. The majority of tumor-specific alterations in ovarian cancers were present in STICs, including those affecting TP53, BRCA1, BRCA2 or PTEN. Evolutionary analyses reveal that p53 signatures and STICs are precursors of ovarian carcinoma and identify a window of 7 years between development of a STIC and initiation of ovarian carcinoma, with metastases following rapidly thereafter. Our results provide insights into the etiology of ovarian cancer and have implications for prevention, early detection and therapeutic intervention of this disease., It has previously been proposed that high-grade serous ovarian carcinoma (HGSOC) may originate from the fallopian tube. Here, the authors analyze genetic aberrances in fallopian tube lesions, ovarian cancers, and metastases from HGSOC patients and establish the evolutionary origins of HGSOC in the fallopian tube.

We developed an automated 2-tiered Fuhrman’s grading system for clear cell renal cell carcinoma (ccRCC). Whole slide images (WSI) and clinical data were retrieved for 395 The Cancer Genome Atlas (TCGA) ccRCC cases. Pathologist 1 reviewed and selected regions of interests (ROIs). Nuclear segmentation was performed. Quantitative morphological, intensity, and texture features (n=72) were extracted. Features associated with grade were identified by constructing a Lasso model using data from cases with concordant 2-tiered Fuhrman’s grades between TCGA and Pathologist 1 (training set n=235; held-out test set n=42). Discordant cases (n=118) were additionally reviewed by Pathologist 2. Cox proportional hazard model evaluated the prognostic efficacy of the predicted grades in an extended test set which was created by combining the test set and discordant cases (n=160). The Lasso model consisted of 26 features and predicted grade with 84.6% sensitivity and 81.3% specificity in the test set. In the extended test set, predicted grade was significantly associated with overall survival after adjusting for age and gender (Hazard Ratio 2.05; 95% CI 1.21-3.47); manual grades were not prognostic. Future work can adapt our computational system to predict WHO/ISUP grades, and validating this system on other ccRCC cohorts.

A chemotherapy response score (CRS) system was recently described to assess the histopathologic response and prognosis of patients with tubo-ovarian high-grade serous carcinoma (HGSC) receiving neoadjuvant chemotherapy. The current study was performed as an independent assessment of this CRS system. We retrospectively identified advanced stage HGSC patients who received neoadjuvant chemotherapy and underwent interval debulking. If available, a hemotoxylin and eosin slide from the omentum and the adnexa was selected for the study. Slides were independently scored by 13 pathologists using the 3-tiered CRS system. Reviewers then received web-based training and rescored the slides. Overall survival and progression-free survival were estimated using the Kaplan-Meier method and compared using the log-rank test. A total of 68 patients with omental (n=65) and/or adnexal (n=59) slides were included in the study. Interobserver reproducibility was moderate for omentum (κ, 0.48) and poor for adnexa (κ, 0.40), which improved for omentum (κ, 0.62) but not for adnexa (κ, 0.38) after online training. For omental slides, a consensus CRS of 1/2 was associated with a shorter median progression-free survival (10.9 mo; 95% confidence interval, 9-14) than a CRS of 3 (18.9 mo; 95% CI, 18-24; P=0.020). In summary, a 3-tiered CRS system of hemotoxylin and eosin-stained omental deposits can yield prognostic information for HGSC patients receiving neoadjuvant chemotherapy, and web-based training improved reproducibility but did not alter determination of clinical outcomes. The CRS system may allow oncologists to identify potential nonresponders and triage HGSC patients for heightened observation and/or clinical trials.

In surgical pathology, an understanding of the normal ovarian anatomy and the range of nonneoplastic lesions of the ovary is essential during the examination of gynecological specimens. Pathologists routinely evaluate nonneoplastic adult ovaries as components of (1) hysterectomy procedures for uterine leiomyomata, uterine prolapse, vaginal bleeding, or gynecological cancer and (2) risk-reducing prophylactic salpingo-oophorectomy, with the primary goals of excluding ovarian malignancy and/or determining whether the ovary is the source of hormone production driving uterine cancer. In these scenarios, with the exception of endometriosis, ovarian infection, or a hormone-producing lesion, any incidental nonneoplastic lesion encountered in the ovary is likely not of clinical significance. However, another frequently encountered scenario is examination of the ovary via biopsy, cystectomy, or excision for a specific purpose, including ovarian enlargement, cyst formation, masses, torsion, infection, infertility, or ectopic pregnancy, in which the ovary is submitted for evaluation for a clinical or radiological reason. Each of these settings requires the pathologist to have knowledge of the normal ovarian anatomy, the histology, and the range of nonneoplastic lesions of the ovary in order to guide the obstetrician-gynecologist or gynecologic oncologist to the appropriate treatment and follow-up.

481 Background: mBSCC is an uncommon form of urinary bladder malignancy when compared with the much higher urothelial carcinoma incidence. We studied the genomic alteration (GA) landscape in a series of mBSCC based on the association with HPV-16 to determine if differences would be observed between the positive and negative groups. Methods: Using a hybrid capture-based FDA-approved CGP assay, a series of 171 mBSCC were sequenced to evaluate all classes of GA. Tumor mutational burden (TMB) was determined on up to 1.1 Mbp of sequenced DNA and microsatellite instability (MSI) was determined on 114 loci. PD-L1 expression was determined by IHC (Dako 22C3) with low tumor cell positive staining set at 1-49% and high staining at ≥50% expression. Results: Overall, 11 (6.4%) of the mBSCC were found to harbor HPV-16 sequences (Table). HPV-16+ status was identified slightly more often in women (NS) and in younger patients (P = .04); 2 female patients with mBSCC had prior history of SCC including 1 anal SCC and 1 vaginal SCC. HPV-16+ mBSCC had fewer GA/tumor (P < .0001), and fewer inactivating GA in CDKN2A (P < .0001), CDKN2B (P = .05), TERT promoter (P = .0004) and TP53 (P < .0001). GA in genes associated with urothelial carcinoma including FGFR2 and FGFR3 were similar in both HPV-16+ and HPV-16- mBSCC groups. MTOR and PIK3CA pathway GA were not significantly different in the 2 groups. MSI and TMB were also similar in the 2 groups. The 3 HPV-16+ mBSCC cases showed high positive PD-L1 IHC staining. Conclusions: HPV-16+ mBSCC tends to occur more often in women and younger patients. As reported in other HPV-associated squamous cell carcinomas, HPV-16+ mBSCC demonstrates significantly reduced frequencies of inactivating mutations in cell cycle regulatory genes with similar GA in MTOR and PIK3CA pathways. The implication of HPV in the pathogenesis of bladder cancer remains unknown but warrants further exploration and clinical validation. [Table: see text]

163 Background: Herpesvirus HHV-8 has been detected in normal prostate tissue and has been linked to the acquisition of androgen-independent growth of prostate cancer cells in vitro, early development of anti-androgen therapy resistance, and more aggressive disease in a subset of patients with mCRPC. We used comprehensive genomic profiling (CGP) to test the hypothesis that HHV-8 associated mCRPC is a distinct molecular subset of mCRPC featuring altered AR signaling compared to HHV-8 negative mCRPC. Methods: Using a hybrid capture-based FDA-approved CGP assay, a series of 4,918 mCRPC were sequenced to evaluate all classes of genomic alterations (GAs). Tumor mutational burden (TMB) was determined on up to 1.1 Mb of sequenced DNA and microsatellite instability (MSI) was determined on 114 loci. PD-L1 expression was determined by IHC (Dako 22C3). HHV-8 status was determined by CGP-based identification of unique viral reads. Results: Overall, 128 (2.6%) of the mCRPC cases harbored HHV-8 sequences (Table). The patient age distribution was similar in the HHV-8+ and HHV-8− groups. GAs in AR, predominantly amplifications, and RAD21 were slightly reduced in HHV-8+ mCRPC cases (P = .01 for both). The frequencies of GAs in genes associated with mCRPC including PTEN, BRCA2, ATM, CDK12, and the TMPRSS2: ERG fusion were similar in the two groups. HHV-8+ patients were less likely to be of European ancestry (P = 0.001). Putative biomarkers associated with immunotherapy response (MSI status, TMB, and PD-L1 expression) were also similar in the two groups. Conclusions: HHV-8+ mCRPC is a rare sub-type of mCRPC with lower frequency of AR GAs compared to HHV-8− mCRPC cases, suggesting a potential role of HHV-8 in inducing androgen-independent prostate cancer growth. Additional alterations associated with potentially enhanced PARP inhibitor response seen in HHV-8+ mCRPC (e.g., RAD21) suggest that early performance of CGP may inform precision treatment strategies to be tested in clinical trials. [Table: see text]

2 Background: Although SCC of the penile skin (pSCC) and the male urethral surface epithelium (uSCC) arise in nearby locations and can feature similar histology, their clinical manifestations, disease course, and surgical and medical treatment options are distinct. We performed CGP on pSCC and uSCC to examine genomic profiles differences. Methods: Tissues obtained from men with clinically advanced pSCC (n = 230) and uSCC (n = 17) underwent hybrid capture-based CGP to evaluate all classes of genomic alterations (GAs). Tumor mutational burden (TMB) was determined on up to 1.1 Mb of sequenced DNA and microsatellite instability (MSI) was determined on up to 114 loci. PD-L1 expression was determined by IHC (Dako 22C3). Results: The median ages were similar in both groups. pSCC exhibited a slightly higher frequency of HPV-16/18 infection (29% vs. 12%, P = .16), although the TP53 mutation frequencies were nearly identical (55% vs. 59%, NS). CDKN2A inactivation (P = .08), CCND1 amplification trending higher and TERT promoter mutations (P = .01) were more frequent in pSCC, potentially indicating prior HPV infection. GAs in NOTCH1 were exclusively identified in pSCC. Potentially actionable GAs identified in both groups included PIK3CA activating mutations (TKIs) as well as pathogenic alterations in FBXW7 and PTEN (MTOR inhibitors). Rare BRCA1 and BRCA2 inactivation (PARP inhibitors) was seen in pSCC only. High-positive PD-L1 staining was elevated in pSCC (34 vs. 14%, P = .06). Although average TMB was similar in both groups, pSCC exhibited an elevated frequency of cases with CD274 ( PD-L1) amplification as well as TMB >10 mut/Mb which are on label for immune checkpoint inhibitor (ICPI) treatment. Conclusions: CGP of pSCC and uSCC identifies opportunities for both targeted and ICPI therapies. Compared to uSCC, pSCC had genomic features more similar to head and neck SCC including slightly increased cell-cycle perturbation, HPV infection, and NOTCH pathway signaling alterations. Further use of CGP in the treatment planning for pSCC and uSCC may be warranted. [Table: see text]

Highlights • KRAS mutation is a major driver in mesonephric and mesonephric-like carcinomas of cervical, endometrial or ovarian origin. • ARID1A and PIK3CA mutations were also identified in endometrial and ovarian mesonephric-like carcinomas. • Peripheral blood ctDNA liquid biopsy may detect mutations in recurrent and/or metastatic mesonephric carcinomas., Mesonephric carcinoma is a rare cancer that most often arises within the cervix, and less frequently, in the ovary and endometrium. A retrospective search of our CLIA-certified and CAP-accredited reference molecular laboratory database (Foundation Medicine, Inc.) identified 20 mesonephric or mesonephric-like, cervical (n = 10), endometrial (n = 5), ovarian (n = 4) or peri-bladder (n = 1) carcinomas that had undergone comprehensive genomic profiling via next generation sequencing. Activating KRAS mutations were present in 90%, 18 of 20 cases, including G12V (n = 7), G12D (n = 6), G12A (n = 3) and G12C (n = 2). Other recurrent alterations were identified in ARID1A (25%), PIK3CA (20%), CTNNB1 (15%), TP53 (10%), MLL2 (10%) and CDKN2A (10%). One KRAS wild-type case had a GATA3 mutation as the sole alteration, while the second KRAS wild-type case had an EGFR exon 20 insertion D770_N771insSVD alteration. All tumors were negative for HPV DNA, microsatellite instability, high tumor mutational burden and homologous recombination deficiency. A circulating tumor DNA (ctDNA) liquid biopsy from peripheral blood, which was performed 6 years after original solid tumor resection in one patient with suspected lung metastasis, revealed concordance of KRAS alteration, gains of chromosomes 1q, 2, 10, 12 and 20, plus new TP53 alterations in the liquid biopsy compared to the original sample. KRAS G12 mutation is major driver of mesonephric and mesonephric-like carcinomas, with less frequent contribution by ARID1A and PIK3CA pathways in tumors of non-cervical origin. ctDNA liquid biopsy may be useful in detecting mutations in recurrent or metastatic patients, who may potentially be eligible for trials against emerging targeted therapies.

1053 Background: Prior to use of cell cycle inhibitor drugs such as palbociclib, mutations in the retinoblastoma cell cycle inhibitory gene ( RB1) were extremely uncommon. To assess recent descriptions of RB1 mutations in MBC as treatment related, we compared primary untreated ER+ breast cancer samples from patients who developed MBC with ER+ MBC metastasis biopsies in post-primary treatment patients. Methods: Extracted DNA from 15 untreated primary breast tumors (PBx) and 36 treated metastatic MBC tumors (MBx) were sequenced by hybrid capture genomic profiling to evaluate all classes of genomic alterations (GA). Tumor mutational burden (TMB) was determined on up to 1.1 Mbp of sequenced DNA. PD-L1 expression was determined by IHC (Dako 22C3). Results: The age distribution, GA per tumor, CDH1 and ERBB2 GA frequencies were similar in PBx and MBx. GA in ESR1 (P < 0.0008), classically associated with acquired hormonal therapy resistance, and PIK3CA (p < 0.11) were increased in the MBx vs the PBx samples. RB1 GA were more frequent in the MBx samples (11%) than the pre-treatment PBx samples (0%, P < 0.31). GA not associated with targeted therapy programs were similar in both groups. In addition to low frequencies of ERBB2 amplification in the ER+ tumors, the most frequent potentially targetable GA identified in both PBx and MBx included GA in FGFR1 and NF1. BRCA1 GA were identified in the MBx group only. Biomarkers of potential immunotherapy benefit including MSI status, TMB levels and PD-L1 IHC staining were at similarly low levels in both groups. Additional cases are being identified to expand the cohort sizes for final presentation. Conclusions: In addition to the well-known acquisition of hormonal therapy resistance mutations in ESR1 and PIK3CA in ER+ MBC, this study also supports the acquisition of RB1 mutations when post-treatment metastasis biopsies are sequenced rather than pre-treatment primary tumors. This increase in RB1 mutation identification is associated with exposure of the tumors to anti-cell cycle drugs such as palbociclib in the treated but not the untreated cohort. [Table: see text]

11521 Background: We queried whether comprehensive genomic profiling (CGP) could differentiate genomic alteration (GA) differences in mChor based on tumor site of origin Methods: 111 mChor FFPE tissues were sequenced using a hybrid-capture based CGP method to evaluate all classes of genomic alterations (GA). Tumor mutational burden (TMB) was determined on up to 1.1 Mbp of sequenced DNA and microsatellite instability (MSI) was determined on 114 loci. Results: 27 clivus (Cliv), 12 cervical (Cerv), 10 thoracic (Thor) and 44 lumbosacral (Sacr) mChor were compared (Table). A separate set of 18 mChor were submitted as metastasis biopsies with no primary tumor site available (Unk). mChor was generally more common in men with Sacr tumors. Cliv patients were significantly younger (p = 0.00002). GA/tumor was highest in Sacr at 2.9 and lowest Thor at 1.5. All (100%) mChor were MSI stable and the TMB was low ( < 5 mut/Mb) for all cases. CDKN2A and CDKN2B mutation frequencies were highest in Sacr (52% and 46%, p = 0.009 and 0.0109). Potentially actionable GA in PTEN were highest in Thor and Sacr. PTCH1 GA were seen in Cliv and Cerv and PBRM1 GA potentially associated with immune-oncology (IO) drug response were present in all groups. Additional noteworthy targets were seen in all groups but were found in less than 11% of cases throughout the study (Table). Conclusions: Genomic profiles of our mChor cohort differ based on the site of tumor origin in the axial spine. Sacr appear to have the highest frequency of GA and the greatest number of potentially targetable GA. Although MSI and TMB biomarker results do not predict responsiveness, a significant PBRM1 GA frequency in all groups raises the possibility of IO drug benefit for some patients. [Table: see text]

5534 Background: Comprehensive genomic profiling (CGP) was done on pre-systemic treatment (pre) PT, post-treatment (post) MET sites and LB in PC to uncover differences in genomic alterations (GA) and potential impact on therapy selection. Methods: 1,294 PC tissues and 782 LB underwent hybrid-capture based CGP. PT biopsies and resections were compared with post-treatment MET biopsies from bone (BO), liver (LIV), lung (LU), brain (BN), lymph node (LN) and soft tissue (ST) sites and LB. TMB was determined on up to 1.1 Mbp of sequenced DNA for tumor samples. Tumor cell PD-L1 IHC was measured (Dako 22C3). Results: Differences in alteration frequencies between PT, MET and LB for selected genes are shown in the Table. TMPRSS2:ERG fusion frequencies were similar between PT and MET (35% vs 33%) but varied between MET sites (27% in BO and ST to 40% in LN). GA in AR were lowest in pre PT (2%) and highest in MET (24% in LU to 50% in LIV). BN had the highest GA/tumor (8) and the most PTEN GA. BRCA2 GA frequency varied from 0% in BN to 15% in LI. Potential predictors of IO response included CDK12 GA (16% in LU) and MSI high status (29% in BN). High PD-L1 expression was found in only two cases (LN) and low PD-L1 expression was relatively uncommon. ERBB2 amplifications were increased in MET compared with PT. RB1 GA were increased in LIV cases. LB GA had a similar increase in AR and TP53 GA to MET and appeared to be a blend of MET site biopsies across alteration frequencies. Conclusions: CGP of PT, MET and LB in PC demonstrates differences most likely associated with exposure to systemic therapies. Differences identified in the MET GA landscape suggest that liquid biopsies may capture a broader range of therapeutic opportunities for PC patients. [Table: see text]