Phoebe M Hammer

Folate receptor alpha ( FRα / FOLR1 ) and HER2 immunohistochemical staining in high‐grade endometrial carcinoma with aberrant p53 expression

Aims Mirvetuximab soravtansine is an anti‐FOLR1 (folate receptor 1/alpha) antibody–drug conjugate with a companion diagnostic immunohistochemical (IHC) biomarker for platinum‐resistant ovarian, fallopian tube and primary peritoneal carcinoma. Its effectiveness has sparked interest in FOLR1 expression in endometrial carcinoma. We evaluate the relationship of FOLR1 and HER2‐IHC expression in high‐grade p53‐aberrantly expressed endometrial carcinomas, as overexpression of both is associated with high‐grade histologic features and aggressiveness. Methods and results Carcinomas were scored for HER2‐IHC by both gastric and endometrial serous criteria and FOLR1‐IHC by Ventana package insert on tissue microarray cores. Intratumoral heterogeneity was quantified for HER2 and FOLR1 expression across multiple cores from the same tumour. A total of 291 cores (226 endometrial serous, 47 high‐grade endometrioid and 18 high‐grade Müllerian carcinoma, nos) were collected from 66 cases (discrete accession dates) from 62 patients. When stratified by two‐category HER2‐IHC status (0/1+ vs. 2+/3+, either criteria), significantly more HER2 2+/3+ cores (16/133, 12%) were FOLR1‐positive by a ≥75% cut‐off than HER2 0/1+ specimens (8/158, 5%, P  = 0.031). Results were similar by a ≥25% cut‐off (49/133, 37% vs. 38/158, 24%; P  = 0.018). More cases with high HER2‐IHC heterogeneity (2–3‐pt difference) also demonstrated FOLR1‐IHC heterogeneity (≥50% score difference between cores from the same case) than cases with no or low (1‐pt) HER2‐IHC heterogeneity, though most cases did not show high HER2 or FOLR1 intratumoral heterogeneity (16.7%–18.2% 2–3‐pt difference and 12.1% ≥50% score difference). Conclusions A positive correlation between HER2 and FOLR1 overexpression may be seen in high‐grade endometrial carcinomas with aberrant p53 expression, which may extend to intratumoral heterogeneity of biomarker expression.

Prognostic performance of FIGO 2023 endometrial carcinoma staging: a comparison to FIGO 2009 staging in the setting of known and unknown molecular classification

AimsThe 2023 FIGO staging criteria for endometrial cancer (EC) introduced marked changes from the 2009 version. The full implication of these changes for patient diagnosis and treatment is unknown. We evaluate the differences in staging and prognostication between the two systems, with and without inclusion of molecular classification.Methods and resultsWe assigned (1) FIGO 2009, (2) 2023 molecular‐agnostic and (3) 2023 molecular‐informed stages to 404 fully staged and molecularly classified patients with EC. Disease‐specific and progression/relapse‐free survival were analysed via the Kaplan–Meier method and compared with log‐rank testing; 118 of 252 (47%) FIGO 2009 stage I patients were upstaged based on histopathological findings alone. Stage I/II subgroup survival distribution analysis showed a worse prognosis in FIGO 2023 IIB and IIC patients. In the molecular‐informed FIGO 2023 system, three of 15 (20%) POLE‐mutated stage I/II cases were downstaged from FIGO 2009 and eight (53%) were downstaged from molecular‐agnostic FIGO 2023. Fifty‐one of 60 (85%) p53‐abnormal tumours were upstaged from the FIGO 2009, whereas 13 of 60 (22%) were upstaged from the 2023 molecular‐agnostic stage. Molecular classification improved prognostic stratification for both 2009 and 2023 FIGO systems.ConclusionsDownstaging based on POLE mutation more accurately represents patient outcomes. However, in the absence of known POLE status, applying molecular‐agnostic FIGO 2023 criteria for stage I/II disease should be conducted with caution. For aggressive histotypes, additionally reporting FIGO 2009 stage should be considered. Upstaging based on substantial lymphovascular space invasion, aggressive histotype with any myometrial invasion and abnormal p53 improves prognostic discernment. Further subdivisions within stage I/II provide minimal additional prognostic information.

Endometrioid Endometrial RNA Index Predicts Recurrence in Stage I Patients

Abstract Purpose: Risk prediction with genomic and transcriptomic data has the potential to improve patient outcomes by enabling clinicians to identify patients requiring adjuvant treatment approaches, while sparing low-risk patients from unnecessary interventions. Endometrioid endometrial carcinoma (EEC) is the most common cancer in women in developed countries, and rates of endometrial cancer are increasing. Experimental Design: We collected a 105-patient case-control cohort of stage I EEC comprising 45 patients who experienced recurrence less than 6 years after excision, and 60 Fédération Internationale de Gynécologie et d'Obstétrique grade-matched controls without recurrence. We first utilized two RNA-based, previously validated machine learning approaches, namely, EcoTyper and Complexity Index in Sarcoma (CINSARC). We developed Endometrioid Endometrial RNA Index (EERI), which uses RNA expression data from 46 genes to generate a personalized risk score for each patient. EERI was trained on our 105-patient cohort and tested on a publicly available cohort of 263 patients with stage I EEC. Results: EERI was able to predict recurrences with 94% accuracy in the training set and 81% accuracy in the test set. In the test set, patients assigned as EERI high-risk were significantly more likely to experience recurrence (30%) than the EERI low-risk group (1%) with a hazard ratio of 9.9 (95% CI, 4.1–23.8; P < 0.001). Conclusions: Tumors with high-risk genetic features may require additional treatment or closer monitoring and are not readily identified using traditional clinicopathologic and molecular features. EERI performs with high sensitivity and modest specificity, which may benefit from further optimization and validation in larger independent cohorts.

POLE-Mutated Uterine Carcinosarcomas: A Clinicopathologic and Molecular Study of 11 Cases

Uterine carcinosarcomas (UCS) are high-grade biphasic neoplasms with generally poor outcomes. Based on The Cancer Genome Atlas molecular classification of endometrial carcinomas, the majority of UCS are classified as copy-number high/serous-like (p53-abnormal); however, a small subset represent other molecular subtypes, including those that harbor POLE mutations. We identified 11 POLE-mutated (POLEmut) UCS across 3 institutions and assessed the clinical, histopathologic, immunohistochemical, and molecular features of these tumors. POLEmut UCS occurred in adult women (median age, 64 years; range, 48-79 years) and usually presented as The International Federation of Gynecology and Obstetrics 2009 clinical stage IA (n = 4) or IB (n = 3). Almost all tumors were predominantly carcinomatous (n = 10), with most showing endometrioid morphology (n = 7), followed by ambiguous (n = 4) and serous (n = 3) histotypes. By immunohistochemistry, 7 tumors showed aberrant or subclonally aberrant expression of p53, 6 of which harbored pathogenic mutations in TP53 by sequencing. Other frequent mutations included PIK3CA (10/11), PTEN (8/11), RB1 (7/11), ARID1A (7/11), ATM (6/11), PIK3RA (5/11), and FBXW7 (4/11). Two tumors demonstrated loss of mismatch repair protein expression, and 1 had subclonal loss. Heterologous differentiation was uncommon, and only chondrosarcomatous type (n = 2) was observed. Mean and median follow-ups were 24.3 and 14.1 months, respectively (range, 1.4-61.1 months). Ten patients (91%) had no recurrences or death from disease, although 3 of these had follow-up periods <1 year. One patient, with the subclonal POLE variant, presented with stage IV disease and died 1.4 months after surgery. In conclusion, POLEmut UCS demonstrate unique morphologic and immunohistochemical features compared with their p53-abnormal counterparts and may have significant prognostic differences. Our study supports full molecular classification of UCS. We also raise awareness for potentially assessing POLE mutation allele frequency and clonality in consideration of classifying a tumor as POLEmut.

Detection of FOXL2 C134W Mutation Status by a Novel BaseScope In Situ Hybridization Assay is Highly Sensitive and Specific for Adult Granulosa Cell Tumors

Adult granulosa cell tumors (AGCTs) are a molecularly distinct group of malignant ovarian sex cord-stromal tumors (SCSTs) characterized by a nearly ubiquitous c.402C>G/p.C134W mutation in FOXL2 (hereafter referred to as "C134W"). In some cases, AGCT exhibits marked morphologic overlap with other SCSTs and has an identical immunophenotype, and molecular testing may be necessary to help confirm the diagnosis. However, molecular testing is time consuming, relatively expensive, and unavailable in many pathology laboratories. We describe the development and validation of an in situ hybridization (ISH) custom BaseScope assay for the detection of the FOXL2 C134W mutation. We evaluated 106 ovarian SCSTs, including 78 AGCTs, 9 juvenile granulosa cell tumors, 18 fibromas (cellular and conventional), and 1 SCST, not otherwise specified, as well as 53 epithelial ovarian tumors (42 endometrioid carcinomas and 11 carcinosarcomas) and 1 STK11 adnexal tumor for the presence or absence of FOXL2 wild-type and FOXL2 C134W RNA expression via BaseScope-ISH. Fifty-one tumors had previously undergone DNA sequencing of the FOXL2 gene. Across the entire cohort, the FOXL2 C134W probe staining was positive in 77 of 78 (98.7%) AGCTs. Two of 81 (2.5%) non-AGCTs also showed positive staining, both of which were epithelial ovarian tumors. The assay worked in tissue from blocks >20 years old. There was 100% concordance between the FOXL2 sequencing and BaseScope-ISH results. Overall, assessment of FOXL2 mutation status by custom BaseScope-ISH demonstrated 98.7% sensitivity and 97.5% specificity for the diagnosis of AGCT. BaseScope-ISH for FOXL2 C134W represents a reasonable alternative to sequencing, is quicker and less expensive, and is more easily incorporated than molecular testing into many pathology laboratories. It also has the advantage of requiring less tissue, and the neoplastic cells can be directly visualized on stained sections.

A Subset of SMARCB1 (INI‐1)‐deficient vulvar neoplasms express germ cell markers

AimsSMARCB1 (INI‐1)‐deficient vulvar neoplasms comprise a group of rare tumours that include epithelioid sarcoma (ES), myoepithelial carcinoma (MEC), the recently described myoepithelioma‐like tumour of the vulvar region (MELTVR), and sarcomas that are difficult to classify. It has been suggested that so‐called vulvar yolk sac tumours (YST) may represent morphologic variants of SMARCB1‐deficient tumours; thus, we investigated the immunoreactivity of germ cell markers in SMARCB1‐deficient vulvar neoplasms.Methods and resultsTen SMARCB1‐deficient vulvar neoplasms were stained with germ cell tumour markers (SALL4, glypican‐3, OCT3/4, and AFP) and re‐reviewed for morphologic features. The tumours occurred in adult females (median age 41 years) and included ES (n = 7), MELTVR (n = 2), and MEC (n = 1). All cases showed loss of SMARCB1 expression. Four cases (40%) were focally positive for SALL4 in areas with morphology of typical‐appearing ES. One of these cases also showed focal staining for OCT3/4. One ES showed a transition from typical‐appearing ES to YST‐like morphology, with diffuse expression of SALL4 and glypican‐3, and focal expression of AFP, in these latter areas. All other tested cases were negative for AFP.ConclusionOur study reveals that SALL4, glypican‐3, and OCT3/4 are positive in a subset of SMARCB1‐deficient vulvar neoplasms, which may pose a diagnostic challenge and result in consideration of a germ cell tumour. We also highlight a case with transition from ES to YST‐like morphology, lending further support that YSTs of the vulva are somatically derived SMARCB1‐deficient neoplasms and do not represent true germ‐cell neoplasia.

Clinicopathologic and Molecular Features of Tubo-Ovarian Carcinosarcomas with an Emphasis on p53 Wild-Type, KRAS-Mutated Tumors.

Tubo-ovarian carcinosarcomas (OCS) are uncommon, aggressive tumors. Recent literature in uterine carcinosarcomas has shown prognostic differences by the molecular classification established by The Cancer Genome Atlas. Our aim was to delineate the molecular subtypes within OCS and associated clinicopathologic, immunohistochemical, and additional molecular features. A total of 57 OCS were identified at our institution. The overall median follow-up period was 32.3 months, and 5-year survival rates were 71% (stage I/II), 42% (stage III), and 17% (stage IV). Fifty-one (89%) tumors were of the p53-abnormal molecular subtype. Five (9%) tumors were of no specific molecular subtype, and all 5 of these tumors harbored canonical mutations in KRAS (codon 12). We also identified the first reported primary POLE-mutated OCS in a patient with Lynch syndrome; this case was assigned as of a double-classifier POLE-mutated/mismatch repair-deficient molecular subtype. No tumors were of the single-classifier mismatch repair-deficient or POLE-mutated molecular subtype. Compared with the p53-abnormal tumors, KRAS-mutated tumors occurred in younger women at lower stages, but did recur in 2 out of 5 (40%) patients. They always showed endometrioid rather than high-grade serous morphology and were usually ER, PR, and WT1 negative. Three KRAS-mutated tumors also had at least focal mesonephric-like histology. Although rare, p53 wild-type tumors represent a small subset of OCS that show distinct clinical and histologic features and are largely driven by KRAS mutations.