Integrated mutational landscape analysis of poorly differentiated high-grade neuroendocrine carcinoma of the uterine cervix.

High-grade neuroendocrine cervical cancers (NETc) are exceedingly rare, highly aggressive tumors. We analyzed 64 NETc tumor samples by whole-exome sequencing (WES). Human papillomavirus DNA was detected in 65.6% (42/64) of the tumors. Recurrent mutations were identified in PIK3CA, KMT2D/MLL2, K-RAS, ARID1A, NOTCH2, and RPL10. The top mutated genes included RB1, ARID1A, PTEN, KMT2D/MLL2, and WDFY3, a gene not yet implicated in NETc. Somatic CNV analysis identified two copy number gains (3q27.1 and 19q13.12) and five copy number losses (1p36.21/5q31.3/6p22.2/9q21.11/11p15.5). Also, gene fusions affecting the ACLY-CRHR1 and PVT1-MYC genes were identified in one of the eight samples subjected to RNA sequencing. To resolve evolutionary history, multiregion WES in NETc admixed with adenocarcinoma cells was performed (i.e., mixed-NETc). Phylogenetic analysis of mixed-NETc demonstrated that adenocarcinoma and neuroendocrine elements derive from a common precursor with mutations typical of adenocarcinomas. Over one-third (22/64) of NETc demonstrated a mutator phenotype of C > T at CpG consistent with deficiencies in MBD4, a member of the base excision repair (BER) pathway. Mutations in the PI3K/AMPK pathways were identified in 49/64 samples. We used two patient-derived-xenografts (PDX) (i.e., NET19 and NET21) to evaluate the activity of pan-HER (afatinib), PIK3CA (copanlisib), and ATR (elimusertib) inhibitors, alone and in combination. PDXs harboring alterations in the ERBB2/PI3K/AKT/mTOR/ATR pathway were sensitive to afatinib, copanlisib, and elimusertib (P < 0.001 vs. controls). However, combinations of copanlisib/afatinib and copanlisib/elimusertib were significantly more effective in controlling NETc tumor growth. These findings define the genetic landscape of NETc and suggest that a large subset of these highly lethal malignancies might benefit from existing targeted therapies.

Extrauterine epithelioid trophoblastic tumour and its somatic carcinoma mimics: short tandem repeat genotyping meets the diagnostic challenges.

AIMS: While epithelioid trophoblastic tumour (ETT) primarily arises from the uterus, cases have been increasingly documented at extrauterine sites, originating from an ectopic gestation or presenting as a metastatic tumour, leading to the major differential diagnosis of somatic carcinoma with trophoblastic differentiation. The precise separation of a gestational trophoblastic tumour from its somatic carcinoma mimics is highly relevant and crucial for patient management and prognosis. METHODS AND RESULTS: We summarise the clinicopathological and molecular features of four challenging epithelioid malignancies presenting at extrauterine sites, with ETT as the main differential diagnosis. All four tumours demonstrated histological and immunohistochemical features overlapping between a somatic carcinoma and an ETT, combined with inconclusive clinical and imaging findings. Serum beta-hCG elevation was documented in two cases. Short tandem repeat (STR) genotyping was performed and was informative in all cases. The presence of a unique paternal allelic pattern in the tumour tissue confirmed the diagnosis of ETT in two cases with an initial consideration of either somatic carcinoma or suspicion of a gestational trophoblastic tumour. The presence of matching genetic profile with the patient's paired normal tissue was seen in two other cases (both initially considered as ETT), confirming their somatic origin, including one metastatic triple-negative breast carcinoma and one primary lung carcinoma. CONCLUSIONS: Diagnostic separation of ETT at an extrauterine site from its somatic carcinoma mimics can be difficult at the histological and immunohistochemical levels. STR genotyping offers a robust ancillary tool that precisely separates ETT from somatic carcinomas with trophoblastic differentiation.

Diandric triploid partial mole versus digynic nonmolar triploidy: is morphological assessment sufficient for the diagnostic distinction?

AIMS: Diagnostic separation of diandric triploid gestation, i.e. partial mole from digynic triploid gestation, is clinically relevant, as the former may progress to postmolar gestational trophoblastic neoplasia. The aim of the study was to investigate if the combination of abnormal histology combined with ploidy analysis-based triploidy is sufficient to accurately diagnose partial mole. METHODS AND RESULTS: A genotype-phenotype correlation study was undertaken to reappraise histological parameters among 20 diandric triploid gestations and 22 digynic triploid gestations of comparable patient age, gestational weeks, and clinical presentations. Two villous populations, irregular villous contours, pseudoinclusions, and syncytiotrophoblast knuckles, were common in both groups. Villous size ≥2.5 mm, cistern formation, trophoblastic hyperplasia, and syncytiotrophoblast lacunae were significantly more common in the partial hydatidiform mole. Cistern formation had the highest positive predictive value (PPV) (93%) and highest specificity (96%) for diandric triploid gestation, although the sensitivity was 70%. Cistern formation combined with villous size ≥2.5 mm or trophoblast hyperplasia or syncytiotrophoblast lacunae had 100% specificity and PPV, but a marginal sensitivity of 60%-65%. A moderate interobserver agreement (Kappa = 0.57, Gwet's AC1 = 0.59) was achieved among four observers who assigned diagnosis of diandric triploid gestation or digynic triploidy solely based on histology. CONCLUSIONS: None of histological parameters are unique to either diandric triploid gestation or digynic triploid gestation. Cistern formation is the most powerful discriminator, with 93% PPV and 70% sensitivity for diandric triploid gestation. While cistern formation combined with either trophoblastic hyperplasia or villous size ≥2.5 mm or syncytiotrophoblast lacunae has 100% PPV and specificity for diandric triploid gestation, the sensitivity is only 60% to 65%. Therefore, in the presence of triploidy, histological assessment is unable to precisely classify 35% to 40% of diandric triploid gestations or partial moles.

Mixed Gestational Trophoblastic Tumors-Challenging Clinicopathological Presentations.

Mixed gestational trophoblastic tumors are exceptionally rare and have variable clinicopathological presentations. We report 3 such tumors with different combinations of choriocarcinoma (CC), placental site trophoblastic tumor (PSTT), and epithelioid trophoblastic tumor (ETT). The patients' age ranged from 38 to 44 years. Mixed trophoblastic tumor was not considered at the initial diagnosis and all 3 tumors were proven of gestational origin by DNA genotyping. Patient #1 presented with serum human chorionic gonadotropin (hCG) of 97 mIU/mL and a 5.6-cm cervical mass that was initially interpreted as PSTT on biopsy. Hysterectomy revealed a mixed PSTT (60%) and ETT (40%) with extrauterine metastases of only the ETT component. The tumor recurred 15 months after a multiagent chemotherapy and was tested positive for programmed death-ligand 1. The patient received immune checkpoint inhibitor therapy and remained disease-free after 24 months. Patient #2 presented with vaginal bleeding and serum hCG of 46,458 mIU/mL. An endometrial biopsy was interpreted as CC. Recurrence developed in the uterus and lung after methotrexate-based chemotherapy. A mixed CC and ETT were eventually diagnosed upon consultation review. Patient #3 presented with a complete hydatidiform mole and serum hCG of 744,828 mIU/mL. Three months after methotrexate, followed by actinomycin D therapy, a uterine mass was found. Hysterectomy revealed a mixed CC and PSTT. In conclusion, the rarity, elusive presentation, and wide range of histology make the diagnosis of mixed trophoblastic tumors highly challenging. The clinical management and prognosis are dictated by each component of the tumor. CC component must be considered when the patient presents with a high serum hCG level.

Novel FOXL2 Mutation in an Ovarian Adult Granulosa Cell Tumor: Report of a Case With Diagnostic and Clinicopathologic Implications.

Adult granulosa cell tumor, the most common malignant ovarian sex cord-stromal tumor, harbors the characteristic mutation c.402C>G (p.C134W) in the FOXL2 gene in ~90% to 95% of cases. To date, no other variants of FOXL2 mutations have been identified in these tumors. Here we report the first case of an adult granulosa cell tumor with a novel FOXL2 point mutation c.398C>T (p.A133V) presenting in a 64-year-old postmenopausal woman. The patient underwent total hysterectomy and bilateral salpingo-oophorectomy for atypical endometrial hyperplasia and gross examination revealed an incidental 3.2 cm right ovarian mass with a solid, bright yellow, homogeneous cut surface. Microscopically, ~30% of the tumor showed a nested growth pattern composed of uniform tumor cells with oval nuclei and a moderate amount of pale cytoplasm, while the remaining areas consisted of a bland storiform fibromatous stroma. Reticulin stain demonstrated loss of the individual pericellular network within the nested areas, while the pericellular staining pattern was retained in the background stromal component. FOXL2 sequencing analysis was performed in both components and revealed a c.398C>T (p.A133V) mutation in the nested component, whereas wild-type FOXL2 sequence was identified in the fibromatous stroma. Sections from the uterus showed a low-grade endometrioid endometrial adenocarcinoma with superficial myometrial invasion. The patient underwent adjuvant vaginal cuff brachytherapy for the endometrial carcinoma and is alive and well at 8 months follow-up. This case illustrates that new FOXL2 mutations may be detected in ovarian sex cord-stromal tumors with increasing use of routine molecular testing, adding to the complexity of the pathologic diagnosis. In the right morphologic and clinical context, a FOXL2 mutation-even if it is different from the dominant hotspot mutation c.402C>G (p.C134W)-can support the diagnosis of adult granulosa cell tumor.

Targetable ERBB2/HER2 Mutations in Gynecologic Malignancies: Clinicopathological, Immunohistochemical, and Molecular Correlations.

Targeted anti-HER2 therapy has been recently added to the standard treatment recommendations in endometrial serous carcinoma. Current eligibility requires testing for HER2 overexpression and/or gene amplification by immunohistochemistry and by fluorescence in situ hybridization. However, clinical trials have also demonstrated the efficacy of anti-HER2 drugs against activating ERBB2/HER2 mutations in a variety of solid tumor types, and fam-trastuzumab deruxtecan is now approved by the US Food and Drug Administration for HER2-mutant non-small cell lung cancer. This study aimed at evaluating the detailed clinical, histomorphological, immunohistochemical, and molecular characteristics of gynecologic malignancies with ERBB2/HER2 mutations. We identified 16 tumors with 19 ERBB2/HER2 mutations in our departmental archives: 11 endometrial primaries, 2 endocervical adenocarcinomas, 1 ovarian mucinous adenocarcinoma, 1 tubo-ovarian undifferentiated carcinoma, and 1 high-grade endometrioid adenocarcinoma of Mullerian origin. ERBB2/HER2 mutations most often involved the tyrosine kinase domain (52.6%), and the most frequent specific mutation was R678Q (31.6%), involving the juxtamembrane domain. More than half (54.5%) of endometrial carcinomas and half of all tumors were MMR-deficient, resulting from MSH6 loss in all but 2 tumors. None of the tumors (0%) were POLE-mutated, while 18.8% were TP53-mutated. HER2 IHC was negative (score 0 or 1+) in 12 tumors (67%) and equivocal (score 2+) in 4 tumors (33%), whereas none of the tumors were scored as HER2 3+. Score 2+ was associated with R678Q, L755S, I767M mutations, and ERBB2/HER2 rearrangement with a breakpoint in exon 23. Concurrent ERBB2/HER2 amplification was identified in 2 endometrial carcinomas, with HER2/CEP17 ratios of 3.1 and 3.5. We also queried the cBioportal database, which revealed 70 ERBB2/HER2-mutant gynecologic tumors with a total of 77 ERBB2/HER2 mutations, most often involving the active site of the tyrosine kinase domain (n=36; 46.8%), and the most common specific mutation was S310F (n=20; 26%), located in the extracellular domain. Our results provide important details regarding the clinicopathological and molecular associations of potentially actionable ERBB2/HER2 mutations in endometrial carcinoma and other gynecological cancer types and contribute to addressing clinical treatment needs and improving pathology testing recommendations in the future.

Integrated mutational landscape analysis of uterine leiomyosarcomas.

Uterine leiomyosarcomas (uLMS) are aggressive tumors arising from the smooth muscle layer of the uterus. We analyzed 83 uLMS sample genetics, including 56 from Yale and 27 from The Cancer Genome Atlas (TCGA). Among them, a total of 55 Yale samples including two patient-derived xenografts (PDXs) and 27 TCGA samples have whole-exome sequencing (WES) data; 10 Yale and 27 TCGA samples have RNA-sequencing (RNA-Seq) data; and 11 Yale and 10 TCGA samples have whole-genome sequencing (WGS) data. We found recurrent somatic mutations in TP53, MED12, and PTEN genes. Top somatic mutated genes included TP53, ATRX, PTEN, and MEN1 genes. Somatic copy number variation (CNV) analysis identified 8 copy-number gains, including 5p15.33 (TERT), 8q24.21 (C-MYC), and 17p11.2 (MYOCD, MAP2K4) amplifications and 29 copy-number losses. Fusions involving tumor suppressors or oncogenes were deetected, with most fusions disrupting RB1, TP53, and ATRX/DAXX, and one fusion (ACTG2-ALK) being potentially targetable. WGS results demonstrated that 76% (16 of 21) of the samples harbored chromoplexy and/or chromothripsis. Clinically actionable mutational signatures of homologous-recombination DNA-repair deficiency (HRD) and microsatellite instability (MSI) were identified in 25% (12 of 48) and 2% (1 of 48) of fresh frozen uLMS, respectively. Finally, we found olaparib (PARPi; P = 0.002), GS-626510 (C-MYC/BETi; P < 0.000001 and P = 0.0005), and copanlisib (PIK3CAi; P = 0.0001) monotherapy to significantly inhibit uLMS-PDXs harboring derangements in C-MYC and PTEN/PIK3CA/AKT genes (LEY11) and/or HRD signatures (LEY16) compared to vehicle-treated mice. These findings define the genetic landscape of uLMS and suggest that a subset of uLMS may benefit from existing PARP-, PIK3CA-, and C-MYC/BET-targeted drugs.

Trastuzumab deruxtecan (DS-8201a), a HER2-targeting antibody-drug conjugate with topoisomerase I inhibitor payload, shows antitumor activity in uterine and ovarian carcinosarcoma with HER2/neu expression.

OBJECTIVES: Carcinosarcomas are highly aggressive gynecologic malignancies containing both carcinomatous and sarcomatous elements with heterogeneous HER2/neu expression and limited therapeutic options. We compared the efficacy of trastuzumab deruxtecan (DS-8201a), a novel HER2/neu-targeting antibody-drug conjugate (ADC) to an ADC isotype control (MAAA-9199) against primary uterine and ovarian carcinosarcomas in vitro and in vivo. METHODS: Twelve primary carcinosarcoma (CS) cell lines were evaluated for HER2/neu surface expression by immunohistochemistry (IHC) and by flow cytometry, and gene amplification by fluorescence in situ hybridization (FISH) assays. The in vitro experiments included cytotoxicity and bystander killing effect assays on three cell lines of variable HER2/neu expression. In vivo activity was studied in a mouse CS xenograft model of 3+ HER2/neu uterine CS. RESULTS: In vitro studies showed that DS-8201a was highly effective against uterine and ovarian CS cell lines demonstrating 3+ HER2/neu expression compared to MAAA-9199 control; there was no significant improvement in the 0 HER2/neu CS cell line. However, DS-8201a induced efficient bystander killing of 0 HER2/neu tumor cells when admixed with 3+ HER2/neu cells. In vivo studies confirmed that DS-8201a was more effective than MAAA-9199 in 3+ HER2/neu-expressing CS xenografts. CONCLUSION: DS-8201a may represent a novel and highly effective ADC against HER2/neu-expressing CS.

Elimusertib (BAY1895344), a novel ATR inhibitor, demonstrates in vivo activity in ATRX mutated models of uterine leiomyosarcoma.

INTRODUCTION: Uterine leiomyosarcoma (uLMS) is a rare, highly aggressive malignancy. Recent data suggest 50% of uLMS may harbor alterations in the ATRX gene and such mutations may confer sensitivity to ataxia-telangiectasia-and-Rad3-related (ATR) kinase inhibitors. We sought to investigate the in vivo activity of Elimusertib (BAY1895344), a novel ATR-inhibitor, against ATRX-mutated uLMS patient-derived xenografts (PDXs). METHODS: Two fully characterized uLMS (i.e., LEY-11 and LEY-16) were grafted into female CB-17/SCID mice. Treatments with control vehicle or BAY1895344 (20 mg/kg dosed twice daily 3 days on 4 days off) were given via oral gavage and tumor measurements as well as weights obtained twice weekly. Tumor volume differences were calculated with a two-way ANOVA. Mechanistic studies were performed ex vivo using BAY1895344 treated uLMS tumor samples by western blot analysis. RESULTS: Both PDX LEY-11 and PDX LEY-16 harboring ATRX gene mutations demonstrated an aggressive behavior in vivo (i.e., control mice were euthanized on average at day 12.5 for PDX LEY-11 and at day 33 for PDX LEY-16). In both tumor models BAY1895344 20 mg/kg dosed with an intermittent oral schedule was able to induce significant growth inhibition compared to vehicle control treatment (p < 0.001 for both LEY-11 and LEY-16) and prolong median overall survival [PDX LEY-11 (12.5 vs. 42 days, p < 0.001) and PDX LEY-16 (33 vs. 60 days, p < 0.001)]. There were not significant changes in weight between treatment and controls. By western blot assays BAY1895344 exposure decreased phosphorylated-ATR and increased expression of apoptotic molecules in LMS PDXs. CONCLUSIONS: BAY1895344 demonstrates promising in vivo activity against biologically aggressive PDX models of uLMS harboring ATRX mutations, with no significant toxicity. Clinical trials of BAY1895344 in uLMS patients are warranted.

Ovarian and uterine carcinosarcomas are sensitive in vitro and in vivo to elimusertib, a novel ataxia-telangiectasia and Rad3-related (ATR) kinase inhibitor.

BACKGROUND: Carcinosarcoma of the ovary (OCS) and uterus (UCS) are rare highly aggressive malignancies. Ataxia-telangiectasia-and-Rad3-related (ATR) kinase and homologous recombination play a pivotal role in DNA damage repair. Homologous recombination deficiency (HRD) has been demonstrated in >30% of OCS/UCS. We investigated the preclinical activity of elimusertib, a selective ATR kinase inhibitor, against carcinosarcoma (CS) cell lines and xenografts. METHODS: Sensitivity to elimusertib was evaluated in vitro against nine whole exome-sequenced (WES) primary CS cell lines and in vivo against HRD CS xenografts. Western blots were performed to determine baseline ATR and p-ATR protein expression in CS, and ATR pathway downstream effectors and apoptosis markers in CS HRD cell lines after Elimusertib treatment. RESULTS: Out of the 9 CS cell lines, 3 harbored HRD and 6 homologous recombination proficient (HRP) features. Most of CS (i.e., 7/9 = 85%) were found to be sensitive to Elimusertib in vitro. Among the 5 primary CS cell lines with a high-grade pure serous epithelial component, HRD cell lines were more sensitive to elimusertib than HRP tumors (mean IC50 ± SEM HRD CS = 61.3 nM ±15.2 vs HRP = 361.6 nM ±24.4 (p = 0.01)). Baseline ATR and p-ATR protein expression was higher in HRD CS cell lines. Elimusertib showed tumor growth inhibition in HRD CS xenografts (p < 0.0001) and increased overall animal survival (p < 0.0001). Western blot demonstrated dose-dependent inhibition of ATR, p-ATR and its downstream effector p-CHK1, and a dose-dependent increase in caspase-3 expression. CONCLUSIONS: Elimusertib is preclinically active in vitro and in vivo against primary CS cell lines and xenografts, respectively. CS models harboring HRD or with pure/mixed endometrioid histology demonstrated higher sensitivity to ATR inhibition. Clinical trials with elimusertib in CS patients are warranted.

Uterine leiomyosarcomas harboring MAP2K4 gene amplification are sensitive in vivo to PLX8725, a novel MAP2K4 inhibitor.

INTRODUCTION: Uterine leiomyosarcomas (uLMS) are rare, highly aggressive tumors. Up to 30% of uLMS may harbor gain of function (GOF) in the MAP2K4 gene, important for tumor cell proliferation, differentiation and metastasis. We investigated the in vivo activity of a novel MAP2K4 inhibitor, PLX8725, against uLMS harboring MAP2K4 gene-amplification. METHODS: Two fully characterized uLMS (i.e., LEY-11 and LEY-16) were grafted into female CB-17/SCID mice. Treatments with control vehicle or PLX8725 (50 mg/kg) were given via oral gavage daily on weekdays for up to 60 days. Tumor volume differences were calculated with two-way ANOVA. Pharmacokinetic (PK) and mechanistic studies of PLX8725 in uLMS PDX models were also performed. RESULTS: Both uLMS tumors evaluated demonstrated GOF in MAP2K4 (i.e., 3 CNV in both LEY-11 and LEY-16). Tumor growth inhibition was significantly greater in both PDX LEY-11 and PDX LEY-16 treated with PLX8725 when compared to controls (p < 0.001). Median overall survival was also significantly longer in both PDX LEY-11 (p = 0.0047) and PDX LEY-16 (p = 0.0058) treatment cohorts when compared to controls. PLX8725 oral treatment was well tolerated, and PK studies demonstrated that oral PLX8725 gives extended exposure in mice. Ex vivo tumor samples after PLX8725 exposure decreased phosphorylated-ATR, JNK and p38, and increased expression of apoptotic molecules on western blot. CONCLUSION: PLX8725 demonstrates promising in vivo activity against PDX models of uLMS harboring GOF alterations in the MAP2K4 gene with tolerable toxicity. Phase I trials of PLX8725 in advanced, recurrent, chemotherapy-resistant uLMS patients are warranted.

Anastomosing Hemangioma of the Ovary With Leydig Cell Hyperplasia: A Clinicopathologic Study of 12 Cases.

Anastomosing hemangioma is a recently described vascular neoplasm, initially identified in the male genitourinary tract. Since its first description, it has been reported at multiple anatomic sites, including rare cases in the female genital tract, most in the ovary. Herein we report the largest series to date of 12 ovarian anastomosing hemangiomas identified at our institution over a 15-yr period. The patients' age at the time of resection ranged from 50 to 76 yr (median: 62 yr), 3 patients presented with symptomatic pelvic masses, 3 tumors were identified by imaging studies, and the remaining 6 were incidentally discovered in ovaries removed for other indications. All tumors were unilateral, occurred at the ovarian hilum, and contained a vaguely lobulated architecture with sinusoidal-like vessels lined by hobnail endothelial cells with minimal to no cytologic atypia. A rim of luteinized/Leydig cells with abundant, eosinophilic cytoplasm and round, centrally placed nuclei surrounding the hemangioma was present in 9/12 tumors. Reinke crystals were observed in 3 of these 9 tumors. The volume of luteinized cells relative to the vascular proliferation ranged from 2% to 30%. All tumors with luteinized/Leydig cells also displayed numerous small eosinophilic, globular intracytoplasmic inclusions within the endothelial cells. The 3 tumors without luteinized/Leydig cells were exclusively intravascular lesions. Despite the frequent presence of luteinization/Leydig cells none of the patients experienced hormonal manifestations. Awareness of this rare benign ovarian entity is important, as its association with luteinized cells/Leydig cell hyperplasia (often exuberant) may be misinterpreted as a steroid cell tumor, Leydig-cell tumor, or as a mixed stromal-vascular tumor.

Correlative Assessment of p53 Immunostaining Patterns and TP53 Mutation Status by Next-Generation Sequencing in High-Grade Endometrial Carcinomas.

TP53 mutations are frequently identified in the copy number-high molecular subgroup of endometrial carcinomas (ECs). P53 immunohistochemistry (IHC) is a widely used surrogate marker reflecting the mutational status of TP53 , and recent reports have shown ~95% concordance between the two methods in ECs. While these results are promising, studies evaluating the correlation between different p53 IHC staining patterns and comprehensive next-generation sequencing results are still limited. We compared the p53 IHC staining patterns, scored as wild-type, diffuse nuclear overexpression, null/complete absence, and cytoplasmic, to next-generation sequencing results reported by FoundationOneCDx in 43 high-grade ECs: 20 serous ECs, 9 mixed ECs with a serous component, 4 carcinosarcomas with a serous component, and 10 grade 3 endometrioid ECs. The concordance of p53 IHC and TP53 mutation status was 100% (43/43) overall, including 100% (33/33) concordance in tumors with a serous component and 100% (10/10) in endometrioid ECs. Among the 35 tumors with aberrant p53 expression the most commonly observed pattern was diffuse nuclear overexpression seen in 69% (24/35), followed by cytoplasmic staining in 17% (6/35), and complete absence of staining (null) in 14% (5/35) of tumors. Of the 6 tumors with cytoplasmic staining, 4 corresponded to missense mutations within the DNA binding domain (V157F in 2 tumors, and S127P and R280S, in 2 tumor each), while 2 corresponded to nonsense mutations in the tetramerization domain (p.E339*). Our results further support that p53 IHC can serve as an accurate predictor of TP53 alterations in ECs to aid the molecular-based tumor classification and the distinction between tumor histotypes, both of which play an important role in the assessment of clinical prognosis and therapeutic decision making. In addition, our data suggest, that the type and position of TP53 mutation may not directly correlate with the observed p53 IHC pattern in all tumors, and that there may be alternative mechanisms for cytoplasmic localization (other than mutations involving the nuclear localization domain), possibly due to conformational changes or posttranslational modifications of the aberrant p53 protein.

A phase 2 evaluation of pembrolizumab for recurrent Lynch-like versus sporadic endometrial cancers with microsatellite instability.

BACKGROUND: Microsatellite instability-high (MSI-H)/mismatch repair deficiency (dMMR) is a biomarker for responses to immune checkpoint inhibitors (ICIs). Whether mechanisms underlying microsatellite instability alter responses to ICIs is unclear. This article reports data from a prospective phase 2 pilot study of pembrolizumab in patients with recurrent MSI-H endometrial cancer (EC) analyzed by whole exome sequencing (WES) and potential mechanisms of primary/secondary ICI resistance (NCT02899793). METHODS: Patients with measurable MSI-H/dMMR EC confirmed by polymerase chain reaction/immunohistochemistry were evaluated by WES and received 200 mg of pembrolizumab every 3 weeks for ≤2 years. The primary end point was the objective response rate (ORR). Secondary end points included progression-free survival (PFS) and overall survival (OS). RESULTS: Twenty-five patients (24 evaluable) were treated. Six patients (25%) harbored Lynch/Lynch-like tumors, whereas 18 (75%) had sporadic EC. The tumor mutation burden was higher in Lynch-like tumors (median, 2939 mutations/megabase [Mut/Mb]; interquartile range [IQR], 867-5108 Mut/Mb) than sporadic tumors (median, 604 Mut/Mb; IQR, 411-798 Mut/Mb; P = .0076). The ORR was 100% in Lynch/Lynch-like patients but only 44% in sporadic patients (P = .024). The 3-year PFS and OS proportions were 100% versus 30% (P = .017) and 100% versus 43% (P = .043), respectively. CONCLUSIONS: This study suggests prognostic significance of Lynch-like cancers versus sporadic MSI-H/dMMR ECs for ORR, PFS, and OS when patients are treated with pembrolizumab. Larger confirmatory studies in ECs and other MSI-H/dMMR tumors are necessary. Defective antigen processing/presentation and deranged induction in interferon responses serve as mechanisms of resistance in sporadic MSI-H ECs. Oligoprogression in MSI-H/dMMR patients appears salvageable with surgical resection and/or local treatment and the continuation of pembrolizumab off study. Clinical studies evaluating separate MSI-H/dMMR EC subtypes treated with ICIs are warranted.

Randomised phase II trial of weekly ixabepilone ± biweekly bevacizumab for platinum-resistant or refractory ovarian/fallopian tube/primary peritoneal cancer.

BACKGROUND: This multi-center RP2 study assessed activity/safety of ixabepilone + bevacizumab compared to ixabepilone in platinum-resistant/refractory ovarian/fallopian tube/primary peritoneal cancer. Additional objectives were to examine the role of prior bevacizumab and taxanes, and explore class III-ß-tubulin (TUBB3) as a predictive biomarker. METHODS: Participants were randomised to receive ixabepilone 20 mg/m2 days 1, 8, 15 with (IXA + BEV) or without (IXA) bevacizumab 10 mg/kg days 1, 15 every 28 days. Patients were stratified by prior BEV. The primary endpoint was PFS. OS, safety, and ORR served as secondary endpoints. RESULTS: Among 76 evaluable patients who received IXA + BEV (n = 39) compared to IXA (n = 37), the ORR was 33% (n = 13) versus 8% (n = 3)(P = 0.004), durable at 6 months in 37% (n = 14) and 3% (n = 1) (P < 0.001). BEV significantly improved PFS (median:5.5 vs 2.2 months, HR = 0.33, 95%CI 0.19-0.55, P < 0.001) and OS (median:10.0 vs 6.0 months, HR = 0.52, 95%CI 0.31-0.87, P = 0.006). Both regimens were well-tolerated. TUBB3 expression did not predict response. Subgroup analyses revealed minimal effect of prior BEV or taxane resistant/refractory status on response to IXA + BEV. CONCLUSIONS: IXA + BEV is a well-tolerated, effective combination for platinum/taxane-resistant ovarian cancer that extends PFS and likely OS relative to IXA monotherapy. Prior receipt of BEV should not preclude the use of IXA + BEV. TUBB3 is not a predictive biomarker. CLINICAL TRIAL REGISTRATION: NCT3093155.

Synergistic activity of neratinib in combination with olaparib in uterine serous carcinoma overexpressing HER2/neu.

INTRODUCTION: Uterine serous carcinoma (USC) is an aggressive variant of endometrial cancer with a poor prognosis. Approximately 30% of USC overexpress HER2/neu, a recognized target for trastuzumab in advanced/recurrent HER2/neu-positive USC. We evaluated the efficacy of the pan-c-erb inhibitor neratinib and the poly (ADP-ribose)-polymerase (PARP) inhibitor olaparib as single agents and in combination against USC cell lines and xenografts. METHODS: In-vitro cell-viability assays with olaparib, neratinib, and olaparib/neratinib were assessed using flow-cytometry based assays against a panel of USC cell lines with high and low HER2/neu expression. Homologous recombination deficiency (HRD) signatures were evaluated as described by Alexandrov et al. (Nature;2020;578:94-101) while downstream signaling affected by neratinib/olaparib exposure was assessed with immunoblotting. Efficacy of single- versus dual-agent inhibition was evaluated in-vivo using two USC-xenografts with 3+ HER2/neu expression. RESULTS: Neratinib was more potent than olaparib in suppression of in-vitro growth of HER2/neu 3+ cell lines (ARK1: p = 0.0047; ARK2: p = 0.0428) while no difference was noted against HER2/neu 1+ tumors (ARK4). Importantly, the combination of olaparib with neratinib synergistically improved tumor suppression compared to either single-agent in vitro. USC cells exposed to olaparib upregulated HER2/neu expression, while neratinib treatment increased PARP activity (ARK1: p < 0.0001; ARK2: p < 0.0001). Single-agent neratinib transiently inhibited in vivo growth of USC xenografts harboring HER2/neu gene amplification (ARK1: p < 0.05; ARK2: p < 0.05). In contrast, the combination of the two inhibitors caused a stronger and durable growth inhibition in both USC xenografts (ARK1: p < 0.05; ARK2: p < 0.05). CONCLUSION: The combination of olaparib and neratinib is active and synergistic against primary HER2/neu + USC. This combination may represent a novel therapeutic option for USC patients with HER2/neu+, homologous recombination-proficient tumors resistant to chemotherapy.

HER2 Expression in Endometrial Cancers Diagnosed as Clear Cell Carcinoma.

There is increasing evidence that many endometrial cancers (EC) diagnosed as clear cell carcinoma (CCC) have substantial overlap with both serous carcinoma (SC) and endometrioid carcinoma (EmC), not only in terms of morphology and immunophenotype but also by molecular characterization. Now with use of HER2-based therapy in SC, a CCC diagnosis in serous-like tumors has the potential to exclude patients from receiving beneficial therapy. To assess HER2 in CCC in relation to other characteristics, a tissue microarray of archived CCC, EmC, and SC was stained for HER2 alongside a battery of immunostains used in EC. Cases with equivocal HER2 IHC were also assessed by in situ hybridization. HER2 status was assessed in 229 cases (23 CCC, 74 SC, 132 EmC). HER2 was positive in 48% of cases diagnosed as CCC, 19% of SC, and 0% of EmC. Rigorous morphologic and immunophenotypic review by 5 gynecologic pathologists revealed diagnostic disagreement in 8/11 HER2+ cases diagnosed as CCC, with SC as the other major diagnostic consideration. All HER2+ (n=25) cases were MMR-intact and most HER2+ EC had aberrant p53 staining (22/25, 88%); the 3 cases with a wild type pattern for p53 (12%) were all negative for ER. Based on these findings, patients with a diagnosis of CCC should be included in future clinical trials of HER2-targeted therapy. Moreover, given the diagnostic difficulty surrounding CCC, immunohistochemistry-based algorithms that include aberrant p53 and/or the absence of ER expression may provide a more objective means of establishing eligibility criteria than is currently possible using traditional histologic classification.

Dataset for the Reporting of Gestational Trophoblastic Neoplasia: Recommendations From the International Collaboration on Cancer Reporting (ICCR).

Comprehensive pathology reporting of cancers is important for patient management, tumor staging, and prognostication. Standardized cancer datasets are essential in guiding pathology reporting in a consistent and concise manner and this facilitates effective global cancer information exchange and comparison. The International Collaboration on Cancer Reporting (ICCR) is an alliance of several national and international pathology societies in many countries as well as bodies which are involved in tumor classification and staging. One function of the ICCR is to develop evidence-based, standardized reporting datasets for each cancer site. Herein, we report the development of an evidence-based cancer dataset by an ICCR panel of international experts for the reporting of primary uterine gestational trophoblastic neoplasia. We present the core elements that should be included and noncore elements that are recommended for inclusion in pathology reports. Lists of the response values are provided for each element, along with explanatory commentaries. The dataset also discusses controversial issues in the reporting of gestational trophoblastic neoplasia. Such evidence-based and structured pathology datasets developed through an international effort will facilitate consistent and accurate exchange and comparison of epidemiological and pathologic parameters among different populations and countries. This will ultimately improve gestational trophoblastic neoplasia patient care and facilitate future research.

Data Set for the Reporting of Endometrial Cancer: Recommendations From the International Collaboration on Cancer Reporting (ICCR).

Endometrial cancer is one of the most common cancers among women. The International Collaboration on Cancer Reporting (ICCR) developed a standardized endometrial cancer data set in 2011, which provided detailed recommendations for the reporting of resection specimens of these neoplasms. A new data set has been developed, which incorporates the updated 2020 World Health Organization Classification of Female Genital Tumors, the Cancer Genome Atlas (TCGA) molecular classification of endometrial cancers, and other major advances in endometrial cancer reporting, all of which necessitated a major revision of the data set. This updated data set has been produced by a panel of expert pathologists and an expert clinician and has been subject to international open consultation. The data set includes core elements which are unanimously agreed upon as essential for cancer diagnosis, clinical management, staging, or prognosis and noncore elements which are clinically important, but not essential. Explanatory notes are provided for each element. Adoption of this updated data set will result in improvements in endometrial cancer patient care.

Immunohistochemistry in gynecologic carcinomas: Practical update with diagnostic and clinical considerations based on the 2020 WHO classification of tumors.

This review provides an update on immunohistochemistry applications-diagnostic, prognostic, and predictive-in the pathology evaluation of gynecologic carcinomas. The 5th edition of the WHO Classification of Female Genital Tumors introduced important changes in the diagnostic classification of lower genital tract, endometrial, and ovarian carcinomas, with major influence on the routine pathology practice. Lower genital tract carcinomas and their precursor lesions are now classified based on their human papillomavirus (HPV)-associated and HPV-independent pathogenesis, reflecting the clinically significant prognostic differences and impacting the therapeutic decision-making. Immunohistochemical markers have an increasing role in the pathology evaluation of endometrial carcinomas: in addition to their traditional use in the differential diagnosis and histologic subtyping, they have also been recently advocated for prognostic classification as surrogates for the TCGA (The Cancer Genome Atlas) molecular groups. New entities - mesonephric-like adenocarcinoma and gastric (gastrointestinal)-type mucinous adenocarcinoma of the endometrium - have also been added and often require immunostains for diagnostic confirmation. Ovarian carcinomas frequently show overlapping morphologic patterns and heterogeneous appearance within the same tumor, necessitating immunohistochemical work-up. Beyond diagnostic applications, there is increasing clinical demand for screening of inherited cancer syndromes, prediction of prognosis and guiding targeted therapy. Practical issues and pitfalls related to mismatch repair protein immunohistochemistry, HER2, and PD-L1 testing are also discussed.