Sabrina Croce

The KAT6B::KANSL1 Fusion Defines a New Uterine Sarcoma With Hybrid Endometrial Stromal Tumor and Smooth Muscle Tumor Features

Neoplasms harboring a KAT6B/A::KANSL1 fusion were initially reported as benign (leiomyomas) and malignant (leiomyosarcomas, low-grade endometrial stromal sarcomas [LG-ESSs]) uterine neoplasms. However, they may represent an emerging entity characterized by clinical aggressiveness contrasting with a rather reassuring microscopic appearance. Here, we aimed to confirm that this neoplasm is a distinct clinicopathologic and molecular sarcoma and identify criteria that should alert pathologists and lead to KAT6B/A::KANSL1 fusion testing in routine practice. Therefore, we conducted a comprehensive clinical, histopathologic, immunohistochemical, and molecular study, including array comparative genomic hybridization, whole RNA-sequencing, unsupervised clustering, and cDNA mutational profile analyses of 16 tumors with KAT6B::KANSL1 fusion from 12 patients. At presentation, patients were peri-menopausal (median, 47.5 years), and the primary tumors were located in the uterine corpus (12/12, 100%), with an additional prevesical location in 1 (8.3%) of 12 cases. The relapse rate was 33.3% (3/9). All tumors (16/16, 100%) showed morphologic and immunohistochemical features overlapping between leiomyoma and endometrial stromal tumors. A whirling recurrent architecture (resembling fibromyxoid-ESS/fibrosarcoma) was found in 13 (81.3%) of 16 tumors. All tumors (16/16, 100%) exhibited numerous arterioliform vessels, and 13 (81.3%) of 18 had large hyalinized central vessels and collagen deposits. Estrogen and progesterone receptors were expressed in 16 (100%) of 16 and 14 (87.5%) of 16 tumors, respectively. Array comparative genomic hybridization performed on 10 tumors classified these neoplasms as simple genomic sarcomas. Whole RNA-sequencing on 16 samples and clustering analysis on primary tumors found that the KAT6B::KANSL1 fusion always occurred between exons 3 of KAT6B and 11 of KANSL1; no pathogenic variant was identified on cDNA, all neoplasms clustered together, close to LG-ESS, and pathway enrichment analysis showed cell proliferation and immune infiltrate recruitment pathway involvement. These results confirm that the sarcomas harboring a KAT6B/A::KANSL1 fusion represent a distinct clinicopathologic entity, close to LG-ESS but different, with clinical aggressiveness despite a reassuring morphology, for which the KAT6B/A::KANSL1 fusion is the molecular driver alteration.

NTRK and other recently described kinase fusion positive uterine sarcomas: A review of a group of rare neoplasms

AbstractThe landscape of uterine sarcomas has greatly expanded in recent years to include neoplasms with recurrent gene fusions, such as BCOR and YWHAE translocated high‐grade endometrial stromal sarcomas. Sophisticated molecular techniques have also resulted in the description of “new” entities associated with recurrent kinase fusions involving NTRK and RET as well as COL1A1‐PDGFB rearranged uterine sarcomas. These rare neoplasms will be discussed in this review, highlighting that some of the underlying molecular events are clinically actionable and potentially susceptible to targeted therapy. While relatively few of these neoplasms have been described to date, likely being previously lumped under the spectrum of undifferentiated uterine sarcoma, the number of cases will expand in the future given their recognition and the increasing availability of molecular testing. These neoplasms have overlapping morphology (often with a “fibrosarcoma‐like” appearance) and immunohistochemical features, and are characterized by variable clinical outcomes. Although immunohistochemistry may assist in some cases, a definitive subclassification requires confirmatory molecular studies. As these molecular assays may not be routinely available in most laboratories, referral to reference centers may be needed. In order to assist the pathologist, we suggest a diagnostic algorithm for routine practice when dealing with a malignant or potentially malignant uterine spindle cell neoplasm.

Challenges of a tailored immunohistochemistry algorithm for uterine leiomyosarcoma: an integrated analysis of leiomyomas with bizarre nuclei and fumarate hydratase (FH) deficiency

AimsLeiomyomas (LM) are the most common uterine mesenchymal neoplasms and encompass a variety of histological subtypes. Bizarre nuclei are described in both leiomyomas with bizarre nuclei (LM‐BN) and fumarate hydratase‐deficient leiomyomas (FH‐LM), which raise diagnostic concerns regarding leiomyosarcoma (LMS). Recently, an immunohistochemical algorithm to support the diagnosis of LMS based on the genomic landscape of these neoplasms was proposed. This study aimed to evaluate the algorithm's accuracy in distinguishing LM‐BN and FH‐LM from LMS.Methods and ResultsWe collected 68 LM (29 LM‐BN, 30 FH‐LM, and 9 LM) and 9 LMS, along with clinicopathological and molecular data. An immunohistochemical panel comprising p53, Rb, PTEN, ATRX, DAXX, and MDM2 was applied. Nine cases were non‐interpretable due to fixation issues. The algorithm demonstrated 100% accuracy for LM without bizarre nuclei (9/9) and for nonmyxoid LMS (5/5). Notably, 28.6% (14/49) of LM‐BN and FH‐LM exhibited at least two abnormalities, leading to potential misclassification as LMS. However, their clinical course, morphology, and genomic profile supported a benign diagnosis. Frequent alterations included Rb (20/49; 40.8%) and p53 (19/49; 38.8%), particularly in bizarre cells, while no abnormal staining was observed for ATRX, DAXX, or MDM2.ConclusionThe proposed algorithm has limitations in differentiating LMS from LM‐BN and FH‐LM, misclassifying 28.6% of the latter. Accurate interpretation requires proper internal controls, particularly for markers whose loss of expression favours malignancy. Morphology remains central for diagnosis, although integration of molecular data may provide additional insights for a definitive classification in challenging cases.

Genomic profile analysis of leiomyomas with bizarre nuclei and fumarate hydratase deficient leiomyomas: Strengths, weaknesses, and limitations of array‐CGH interpretation

AbstractA close relationship has been demonstrated between genomic complexity and clinical outcome in uterine smooth muscle tumors. We studied the genomic profiles by array‐CGH of 28 fumarate hydratase deficient leiomyomas and 37 leiomyomas with bizarre nuclei (LMBN) from 64 patients. Follow‐up was available for 46 patients (from three to 249 months, mean 87.3 months). All patients were alive without evidence of disease. For 51 array‐CGH interpretable tumors the mean Genomic Index (GI) was 16.4 (median: 9.8; from 1 to 57.8), significantly lower than the mean GI in LMS (mean GI 51.8, p < 0.001). We described three groups: (1) a group with FH deletion (24/58) with low GI (mean GI: 11 vs. 22,4, p = 0.02), (2) a group with TP53 deletion (17/58) with higher GI (22.4 vs. 11 p = 0.02), and (3) a group without genomic events on FH or TP53 genes (17/58) (mean GI:18.3; from 1 to 57.8). Because none of these tumors recurred and none showed morphological features of LMS we concluded that GI at the cut‐off of 10 was not applicable in these subtypes of LM. By integration of all those findings, a GI <10 in LMBN remains a valuable argument for benignity. Conversely, in LMBN a GI >10 or alteration in tumor suppressor genes, should not alone warrant a diagnosis of malignancy. Nine tumors were tested with Nanocind CINSARC® signature and all were classified in low risk of recurrence. We propose, based on our observations, a diagnostic approach of these challenging lesions.

Dissecting the Origin of Heterogeneity in Uterine and Ovarian Carcinosarcomas

Gynecologic carcinosarcomas (CS) are biphasic neoplasms composed of carcinomatous (C) and sarcomatous (S) malignant components. Because of their rarity and histologic complexity, genetic and functional studies on CS are scarce and the mechanisms of initiation and development remain largely unknown. Whole-genome analysis of the C and S components reveals shared genomic alterations, thus emphasizing the clonal evolution of CS. Reconstructions of the evolutionary history of each tumor further reveal that C and S samples are composed of both ancestral cell populations and component-specific subclones, supporting a common origin followed by distinct evolutionary trajectories. However, while we do not find any recurrent genomic features associated with phenotypic divergence, transcriptomic and methylome analyses identify a common mechanism across the cohort, the epithelial-to-mesenchymal transition (EMT), suggesting a role for nongenetic factors in inflicting changes to cellular fate. Altogether, these data accredit the hypothesis that CS tumors are driven by both clonal evolution and transcriptomic reprogramming, essential for susceptibility to transdifferentiation upon encountering environmental cues, thus linking CS heterogeneity to genetic, transcriptomic, and epigenetic influences. Significance: We have provided a detailed characterization of the genomic landscape of CS and identified EMT as a common mechanism associated with phenotypic divergence, linking CS heterogeneity to genetic, transcriptomic, and epigenetic influences.

Trabectedin plus Durvalumab in Patients with Advanced Pretreated Soft Tissue Sarcoma and Ovarian Carcinoma (TRAMUNE): An Open-Label, Multicenter Phase Ib Study

Abstract Purpose: Trabectedin has shown preclinical synergy with immune checkpoint inhibitors in preclinical models. Patients and Methods: TRAMUNE is a phase Ib study investigating the combination of trabectedin with durvalumab through a dose escalation phase and two expansion cohorts, soft tissue sarcoma (STS) and ovarian carcinoma. Trabectedin was given at three dose levels (1 mg/m2, 1.2 mg/m2, and 1.5 mg/m2) on day 1, in combination with durvalumab, 1,120 mg on day 2, every 3 weeks. The primary endpoints were the recommended phase II dose (RP2D) of trabectedin combined with durvalumab and the objective response rate (ORR) as per RECIST 1.1. The secondary endpoints included safety, 6-month progression-free rate (PFR), progression-free survival (PFS), overall survival, and biomarker analyses. Results: A total of 40 patients were included (dose escalation, n = 9; STS cohort, n = 16; ovarian carcinoma cohort, n = 15, 80% platinum resistant/refractory). The most frequent toxicities were grade 1–2 fatigue, nausea, neutropenia, and alanine/aspartate aminotransferase increase. One patient experienced a dose-limiting toxicity at dose level 2. Trabectedin at 1.2 mg/m2 was selected as the RP2D. In the STS cohort, 43% of patients experienced tumor shrinkage, the ORR was 7% [95% confidence interval (CI), 0.2–33.9], and the 6-month PFR was 28.6% (95% CI, 8.4–58.1). In the ovarian carcinoma cohort, 43% of patients experienced tumor shrinkage, the ORR was 21.4% (95% CI, 4.7–50.8), and the 6-month PFR was 42.9% (95% CI, 17.7–71.1). Baseline levels of programmed death-ligand 1 expression and CD8-positive T-cell infiltrates were associated with PFS in patients with ovarian carcinoma. Conclusions: Combining trabectedin and durvalumab is manageable. Promising activity is observed in patients with platinum-refractory ovarian carcinoma. See related commentary by Digklia et al., p. 1745

Diagnostic des sarcomes utérins et tumeurs mésenchymateuses utérines rares à potentiel de malignité. Référentiels du Groupe Sarcome Français et des Tumeurs Rares Gynécologiques

The landscape of uterine sarcomas is becoming more complex with the description of new entities associated with recurrent driver molecular alterations. Uterine sarcomas, in analogy with soft tissue sarcomas, are distinguished into complex genomic and simple genomic sarcomas. Leiomyosarcomas and undifferentiated uterine sarcomas belong to complex genomic sarcomas group. Low-grade and high-grade endometrial stromal sarcomas, other rare tumors associated with fusion transcripts (such as NTRK, PDGFB, ALK, RET ROS1) and SMARCA4-deficient uterine sarcoma are considered simple genomic sarcomas. The most common uterine sarcoma are first leiomyosarcoma and secondly endometrial stromal sarcomas. Three different histological subtypes of leiomyosarcoma (fusiform, myxoid, epithelioid) are identified, myxoid and epithelioid leiomyosarcoma being more aggressive than fusiform leiomyosarcoma. The distinction between low-grade and high-grade endometrial stromal sarcoma is primarily morphological and immunohistochemical and the detection of fusion transcripts can help the diagnosis. Uterine PEComa is a rare tumor, which is distinguished into borderline and malignant, according to a risk assessment algorithm. Embryonal rhabdomyosarcoma of the uterine cervix is more common in children but can also occur in adult women. Embryonal rhabdomyosarcoma of the uterine cervix is almost always DICER1 mutated, unlike that of the vagina which is wild-type DICER1, and adenosarcoma which can be DICER1 mutated but with less frequency. Among the emerging entities, sarcomas associated with fusion transcripts involving the NTRK, ALK, PDGFB genes benefit from targeted therapy. The integration of molecular data with histology and clinical data allows better identification of uterine sarcomas in order to better treat them.

Endometrial carcinoma and immune escape: prognostic relevance of HLA class I loss in NSMP subtype

Aims This study aims to define and characterize human leukocyte antigen class I (HLA‐I) expression in a consecutive series of molecularly classified endometrial carcinomas (ECs), and to evaluate its association with clinicopathologic features, spatial cancer–immune phenotypes and patient prognosis, with a focus on the NSMP (no specific molecular profile) subtype. Methods and results HLA‐I expression was assessed by immunohistochemistry on whole tissue sections from 208 ECs, classified into POLE ‐mutated, MMR‐deficient (MMRd), p53‐abnormal (p53abn) and NSMP subtypes. Loss of HLA‐I was identified in 31% of cases and was associated with adverse features including high‐grade, aggressive histotypes, deep myometrial invasion, substantial lymphovascular space invasion (LVSI), extensive tumour necrosis and an ‘excluded’ immune phenotype. While HLA‐I loss showed no significant prognostic impact in POLE , MMRd or p53abn tumours, it significantly correlated with worse disease‐free survival in NSMP tumours ( P  < 0.001). Multivariate analysis confirmed HLA‐I loss as an independent prognostic factor in early‐stage NSMP ECs, in addition to substantial LVSI, presence of lymph node metastases and spatial cancer–immune phenotypes. Integration of HLA‐I status improved the performance of predictive models over time. Conclusions HLA‐I loss defines a biologically aggressive subgroup within NSMP ECs and is associated with adverse clinicopathologic and immune features. Assessment of HLA‐I expression could refine risk stratification in NSMP ECs, a group traditionally lacking robust prognostic markers and may help identify patients who could benefit from intensified clinical surveillance and future immunomodulatory treatment strategies.

Pan‐TRK immunohistochemistry in gynaecological mesenchymal tumours: diagnostic implications and pitfalls

AimsNTRK‐rearranged sarcomas of the female genital tract mainly occur in the uterus (more commonly cervix than corpus) and are characterized by a “fibrosarcoma‐like” morphology and NTRK gene rearrangements. These neoplasms may exhibit histological overlap with other entities and can present diagnostic difficulties without molecular confirmation. Pan‐TRK immunohistochemistry was developed to identify tumours harbouring NTRK rearrangements. The aim of this study was to characterize pan‐TRK immunohistochemical expression in a large cohort of gynaecological mesenchymal neoplasms and investigate the utility of pan‐TRK immunohistochemistry to distinguish NTRK‐rearranged sarcoma from its mimics.Methods and resultsA total of 473 gynaecological mesenchymal tumours (461 without known NTRK fusions and 12 NTRK‐rearranged sarcomas) were selected. Pan‐TRK immunohistochemistry (EPR17341, Abcam) was performed on whole tissue sections and tissue microarrays. Molecular interrogation of pan‐TRK positive tumours was performed by RNA sequencing or fluorescence in situ hybridization (FISH). Of the 12 NTRK‐rearranged sarcomas, 11 (92%) exhibited diffuse (≥70%) cytoplasmic pan‐TRK staining with moderate/marked intensity, while the other was negative. Eleven (2.4%) additional tumours also exhibited pan‐TRK immunohistochemical expression: three low‐grade endometrial stromal sarcomas, seven high‐grade endometrial stromal sarcomas, and an undifferentiated uterine sarcoma. Molecular confirmation of the absence of NTRK rearrangements was possible in nine of these tumours. Of these nine neoplasms, seven exhibited focal/multifocal (<70%) pan‐TRK cytoplasmic staining with weak/moderate intensity.ConclusionEven though pan‐TRK immunohistochemical expression is not entirely sensitive or specific for NTRK‐rearranged sarcomas, these neoplasms tend to exhibit diffuse staining of moderate/strong intensity, unlike its mimics. Pan‐TRK should be performed in monomorphic uterine (corpus and cervix) spindle cell neoplasms that are negative for smooth muscle markers and hormone receptors and positive for CD34 and/ or S100. Ultimately, the diagnosis requires molecular confirmation.