Leiomyosarcoma Research Articles

Characterizing TP53 mutations in bone and soft tissue sarcoma.

e23521 Background: Tumor protein P53 (TP53) is the most frequently mutated gene in cancer and most mutations inactivate wild type TP53 activity through heterogenous mechanisms. Whether different variants of mutant TP53 have different biologic potencies or clinical outcomes remain unclear. This ongoing study aims to characterize the spectrum of TP53 mutations in patients with bone and soft tissue sarcoma. Methods: We retrospectively identified and analyzed patients with bone and soft tissue sarcoma who underwent MSK-IMPACT (Memorial Sloan Kettering Cancer Center - Integrated Mutation Profiling of Actionable Cancer Targets) next-generation sequencing panel and had at least one mutation in the TP53 gene at Memorial Sloan Kettering Cancer Center. Mutations in the TP53 gene were categorized into the following sub-types: fusion, missense, splice site, or protein-truncating. Hotspots were defined as variants with frequency of 10 or greater. We queried the missense variants for the 800 most frequent variants recorded in the International Agency for Research on Cancer R20 (IARC), which were structurally characterized based on their impact on TP53 protein and rescue potencies with arsenic trioxide (ATO) in vitro (Song et al. Sci Transl Med. 2023). Results: We identified a total of 1257 patients with bone and soft tissue sarcoma who had at least one mutation in TP53. 92.5% of patients had only 1 mutation in TP53. In total, 1363 mutations were detected with 541 variants identified across all sarcoma subtypes. Most TP53 mutations were identified in soft tissue leiomyosarcoma (18.05%), uterine leiomyosarcoma (12.84%), sarcoma not otherwise specified (15.62%), undifferentiated pleomorphic sarcoma (12.11%), and osteosarcoma (7.78%). Of the 541 variants identified, the most frequent alterations were intragenic fusion (6.23%), R175H missense (2.93%), R248Q missense (2.27%), R273H missense (2.13%), and R213* protein-truncating (2.05%) mutations. Of the 800 most frequent missense variants in IARC R20 database, 233 missense variants were detected representing 52% of all mutations detected. Structural or likely structural mutations represented most of the identified missense mutations (77.46%). These mutations were clustered in the following hotspots: R175H, Y220C, R282W, H179Y, and C135Y. DNA-contact mutations were clustered in the following hotspots: R248Q, R273H, R273C, and R248W. Conclusions: This analysis highlights the heterogenous landscape of TP53 mutations in bone and soft tissue sarcomas. Structural variants are prevalent in sarcoma and occur at hotspots that may represent novel drug targets in the future.

Neoadjuvant treatment with camrelizumab in combination with doxorubicin and ifosfamide: A phase II clinical study of high-risk soft tissue sarcoma.

e23548 Background: Surgery remains the cornerstone in the management of non-metastatic soft tissue sarcomas. However, high rate of recurrence and metastasis are not uncommon in patients(pts) with high-risk soft tissue sarcoma. Although doxorubicin plus ifosfamide resulted in better tumor shrinkage which facilitate surgical resection, approaches of reducing recurrence and metastasis are still needed. Chemotherapy combined with PD-1 antibodies showed promising activity in several tumors. To date, there is no study to evaluate the efficacy and safety of camrelizumab combined with chemotherapy for high-risk Soft Tissue Sarcoma. Methods: This is a phase II, open-label single-arm study (NCT04606108), aimed to include pts aged 14-65 with histopathologically confirmed high risk soft tissue sarcoma and ECOG 0-1, at least one measurable lesion. One course of treatment every three weeks (camrelizumab 200 mg on day 1, doxorubicin 37.5 mg/m2 or liposomal doxorubicin 25 mg/m2 on days 1-2, and ifosfamide 3 g/m2 on days 1-3). After completing the 2nd course of chemotherapy, the drug will be stopped for 14 days, and surgery or the next stage of treatment will be carried out according to the efficacy of the treatment. Six courses of preoperative chemotherapy will be administered 2 weeks ± 5 days after surgery based on the effectiveness, followed by radiotherapy (50 Gy in 25 fractions or 60 Gy in 30 fractions.) within 3 months after surgery. The primary objective is the Objective response rate (ORR). Using the Simon minimax 2 stage design, planned sample size is 62 pts with 80% power and alpha of 5% to detect an increase in ORR from 27% to 42%. Interim analysis requiring at least 9 confirmed responses in the first 30 pts to proceed to full accrual. Results: 35 pts completed neoadjuvant therapy and surgery, 30 pts received postoperative adjuvant therapy and 1 patient achieved partial response (PR). Median age was 36.4 years (14-61), 62.8% were females, and 57.1% were ECOG-PS 0. Surgery was performed in 35 pts including 16/35 Synovial Sarcoma (SS), 5/35 Liposarcoma (LPS), 2/35 Myxofibrosarcoma (MFS), 2/35 Undifferentiated pleomorphic sarcoma (UPS), 1/35 Leiomyosarcoma (LMS), 5/35 Malignant mesenchymal tumors and 4/35 other pathologic subtype. The 2-year PFS rate was 84.9%, the 2-year OS rate was 96.77%, and the 2-year RFS rate was 72.6%. The most common grade 3-4 adverse events included leukopenia (37.7%), Neutrophil count decreased (37.7%), Platelet count decreased (20.0%), Blennisthmia (3.1%), and Aspartate aminotransferase increased (0.8%). Conclusions: Camrelizumab combined with doxorubicin, liposomal doxorubicin, and ifosfamide in the perioperative treatment of soft tissue sarcoma pts were safe and tolerable. Survival follow-up is still ongoing to analyze the effect of perioperative immunotherapy combined with chemotherapy on long-term outcomes of pts with soft tissue sarcoma. Clinical trial information: NCT04606108 .

Efficacy and safety of anthracycline combined with alkylating agent for treatment of advanced leiomyosarcoma.

e23558 Background: Leiomyosarcoma(LMS) accounts for 12-14% of all soft tissue sarcomas(STSs) and this STS subtype has high metastatic potential. We evaluated the efficacy and safety of epirubicin combined with temozolomide(EPI-TMZ) for treatment of advanced LMS. Methods: Oral TMZ(200 or 300 mg) was administered each day on days 1-5, and intravenous EPI(60 mg/m2) was administered on days 1-4, with even distribution over these 96h within a 21‐day cycle. After 8 cycles of intensive chemotherapy, monodrug maintenance therapy consisted of TMZ alone(dosing as in the primary therapy, most choices, stop taking medication after 1 year control), and two-drug maintenance therapy consisted of TMZ with thalidomide(only 3 patients). All patients-initiated EPI-TMZ treatment between January 2018 and January 2024. Results: We examined 31 patients who received EPI-TMZ. There were 25 females and 6 males, with average age 50.5 years old. All were unresectable patients derived from abdominal retroperitoneum, uterus, inferior vena cava, mesentery, small intestine, stomach, thighs, elbows, wrists, pancreas, nasal cavity, meantime with distant metastasis. Average Ki67 is above 40%. This was a first-line treatment in 16 patients, a second- or third-line in 13, and a fourth-line in 2. At the time of data cutoff (January 31, 2024), the median PFS was 12.6 months, 1 patient had cCR, 9 PR and 20 SD. The ORR was 32.3%(10/31) and DCR was 96.8%(30/31). The only patient who progressed after two cycles of medication had PMS2 deficiency, and studies have reported that it may have a primary resistance mechanism. Even the shortest disease control period is also 5 months, indicating this regime has significant clinical benefit. Some patients have undergone tumor reduction surgery to improve quality of life after achieving significant tumor relief. The current longest PFS is 42 months up to now and under continuous tumor control. Previous retrospective studies indicated the best mPFS was 9.2 months and the best ORR was 30.9%. 2023 ESMO declared prospective doxorubicin with trabectedin obtained mPFS of 12.19 months. The most common treatment-related adverse effects were leukopenia, neutropenia, thrombocytopenia, anemia, nausea, vomiting, fatigue, and oral mucositis. Two patients had severe febrile neutropenia, but there were no treatment-related deaths, survival data follow-up. Conclusions: EPI-TMZ is potentially effective for treatment of advanced LMS, and the adverse effects appear tolerable. EPI-TMZ may provide better outcomes than reported in previous studies of other treatments for advanced LMS, worth further prospective research.

Molecular characterization of long-term and short-term survivors of metastatic uterine leiomyosarcoma.

Molecular characterization of long-term and short-term survivors of metastatic uterine leiomyosarcoma.

Clinical Implications and Molecular Features of Extracellular Matrix Networks in Soft Tissue Sarcomas.

The landscape of extracellular matrix (ECM) alterations in soft tissue sarcomas (STS) remains poorly characterized. We aimed to investigate the tumor ECM and adhesion signaling networks present in STS and their clinical implications. Proteomic and clinical data from 321 patients across 11 histological subtypes were analyzed to define ECM and integrin adhesion networks. Subgroup analysis was performed in leiomyosarcomas (LMS), dedifferentiated liposarcomas (DDLPS), and undifferentiated pleomorphic sarcomas (UPS). This analysis defined subtype-specific ECM profiles including enrichment of basement membrane proteins in LMS and ECM proteases in UPS. Across the cohort, we identified three distinct coregulated ECM networks which are associated with tumor malignancy grade and histological subtype. Comparative analysis of LMS cell line and patient proteomic data identified the lymphocyte cytosolic protein 1 cytoskeletal protein as a prognostic factor in LMS. Characterization of ECM network events in DDLPS revealed three subtypes with distinct oncogenic signaling pathways and survival outcomes. Evaluation of the DDLPS subtype with the poorest prognosis nominates ECM remodeling proteins as candidate antistromal therapeutic targets. Finally, we define a proteoglycan signature that is an independent prognostic factor for overall survival in DDLPS and UPS. STS comprise heterogeneous ECM signaling networks and matrix-specific features that have utility for risk stratification and therapy selection, which could in future guide precision medicine in these rare cancers.

Current landscape of primary small bowel leiomyosarcoma: cases report and a decade of insights

The incidence of leiomyosarcoma (LMS) is about 4–5/100,000 individuals per year. LMSs occurring in the small bowel are even rarer, and their preoperative diagnosis is very difficult. We described two patients with pathologically confirmed small bowel LMS and analyzed their clinical and medical imaging features. Similar cases reported in English in Pubmed database over the past decade were reviewed and summarized. These tumors were categorized by the growth direction and relationship with the intestinal lumen into three types: intraluminal (n = 10), intermural (n = 3), and extraluminal (n = 7). Notably, among the three types of LMS, the intramural leiomyosarcoma stands out as a noteworthy subtype. Emerging evidence suggests that smaller tumor size (< 5 cm) and the intraluminal type may serve as favorable prognostic indicators, while the extraluminal type is associated with relatively poor prognosis. Furthermore, the integration of imaging features with CA125 and LDH biomarkers holds promise for potential diagnostic value in LMS.

Clinical actionability of BRCA2 alterations in uterine leiomyosarcoma: a molecular tumor board case report and a cBioPortal comprehensive analysis.

Uterine leiomyosarcoma (uLMS) represents one of the most common sarcoma histotypes, demonstrating an overall dismal prognosis. Previous studies reported uLMS to carry recurrent somatic BRCA2 homozygous deletions, related to significant clinical benefits from the use of PARP inhibitors. To investigate the prevalence in uLMS of genomic alterations (alt) in BRCA2 and other homologous recombination (HR) and DNA damage response (DDR) genes, cBioPortal was accessed and data were retrieved from studies including pan-sarcoma histologies. HR-/DDR-genes included BRCA1, BRCA2, ATM, BARD1, BRIP1, CHEK1, CHEK2, FANCA, FANCB, FANCC, FANCD2, FANCE, FANCF, FANCG, FANCI, FANCL, FANCM, NBN, PALB2, RAD51C, RAD51D, RAD50, and ATR. Only oncogenic/likely oncogenic alterations were included according to OncoKB. We reported a clinical case of a patient affected by a highly pretreated uLMS discussed at the European Institute of Oncology Molecular Tumor Board. A targeted next-generation sequencing panel demonstrated a somatic BRCA2 homozygous deletion (homDel). Upon access to Niraparib, a remarkable response of 15 months was observed before experiencing disease progression. In the genomic query, among 2393 cases, uLMS (n = 193) displayed 9 of all 31 BRCA2alt observed, representing the only sarcoma histotype showing an enrichment in BRCA2alt (4.66%; q < 0.001). All of 9 BRCA2alt were represented by homDel, which related to a high fraction of genome altered. uLMS displays a significant frequency of somatic BRCA2alt homDel. Considering their dismal prognosis, further investigation is warranted to test the use of PARPi in uLMS, and particularly in the setting of BRCA1/2 alterations.

PI3K/mTOR inhibition induces tumour microenvironment remodelling and sensitises pS6high uterine leiomyosarcoma to PD-1 blockade.

Uterine leiomyosarcomas (uLMS) are aggressive tumours with poor prognosis and limited treatment options. Although immune checkpoint blockade (ICB) has proven effective in some 'challenging-to-treat' cancers, clinical trials showed that uLMS do not respond to ICB. Emerging evidence suggests that aberrant PI3K/mTOR signalling can drive resistance to ICB. We therefore explored the relevance of the PI3K/mTOR pathway for ICB treatment in uLMS and explored pharmacological inhibition of this pathway to sensitise these tumours to ICB. We performed an integrated multiomics analysis based on TCGA data to explore the correlation between PI3K/mTOR dysregulation and immune infiltration in 101 LMS. We assessed response to PI3K/mTOR inhibitors in immunodeficient and humanized uLMS patient-derived xenografts (PDXs) by evaluating tumour microenvironment modulation using multiplex immunofluorescence. We explored response to single-agent and a combination of PI3K/mTOR inhibitors with PD-1 blockade in humanized uLMS PDXs. We mapped intratumoural dynamics using single-cell RNA/TCR sequencing of serially collected biopsies. PI3K/mTOR over-activation (pS6high) associated with lymphocyte depletion and wound healing immune landscapes in (u)LMS, suggesting it contributes to immune evasion. In contrast, PI3K/mTOR inhibition induced profound tumour microenvironment remodelling in an ICB-resistant humanized uLMS PDX model, fostering adaptive anti-tumour immune responses. Indeed, PI3K/mTOR inhibition induced macrophage repolarisation towards an anti-tumourigenic phenotype and increased antigen presentation on dendritic and tumour cells, but also promoted infiltration of PD-1+ T cells displaying an exhausted phenotype. When combined with anti-PD-1, PI3K/mTOR inhibition led to partial or complete tumour responses, whereas no response to single-agent anti-PD-1 was observed. Combination therapy reinvigorated exhausted T cells and induced clonal hyper-expansion of a cytotoxic CD8+ T-cell population supported by a CD4+ Th1 niche. Our findings indicate that aberrant PI3K/mTOR pathway activation contributes to immune escape in uLMS and provides a rationale for combining PI3K/mTOR inhibition with ICB for the treatment of this patient population.

Can endobronchial metastasis from uterine leiomyosarcoma be managed by sleeve lobectomy? A case report and systematic review

Uterine Leiomyosarcoma (uLMS) is an exceptionally rare yet aggressive tumor, characterized by poor clinical outcomes. It exhibits a high potential for metastasis, even long after apparent remission. Surgical excision remains the cornerstone of treatment for localized uLMS and isolated metastatic cases.

Phase Ib Study of Unesbulin (PTC596) Plus Dacarbazine for the Treatment of Locally Recurrent, Unresectable or Metastatic, Relapsed or Refractory Leiomyosarcoma.

This multicenter, single-arm, open-label, phase Ib study was designed to determine the recommended phase II dose (RP2D) and to evaluate the safety and preliminary efficacy of unesbulin plus dacarbazine (DTIC) in patients with advanced leiomyosarcoma (LMS). Adult subjects with locally advanced, unresectable or metastatic, relapsed or refractory LMS were treated with escalating doses of unesbulin orally twice per week in combination with DTIC 1,000 mg/m2 intravenously (IV) once every 21 days. The time-to-event continual reassessment method was used to determine the RP2D on the basis of dose-limiting toxicities (DLTs) assessed during the first two 21-day treatment cycles. All explored doses of unesbulin (200 mg up to 400 mg) were in combination with DTIC. An expansion cohort was enrolled to evaluate the safety and efficacy of unesbulin at the RP2D. Unesbulin 300 mg administered orally twice per week in combination with DTIC 1,000 mg/m2 IV once every 21 days was identified as the RP2D. On the basis of data from 27 subjects who were deemed DLT-evaluable, toxicity was higher in the unesbulin 400 mg group, with three of four subjects (75%) experiencing DLTs versus one of four subjects (25%) in the 200 mg group and three of 19 subjects (15.8%) in the 300 mg group. The most commonly reported DLTs and treatment-related grade 3 and 4 adverse events were thrombocytopenia and neutropenia. At the RP2D, seven subjects who were efficacy evaluable achieved partial response for an objective response rate of 24.1%. Unesbulin 300 mg twice per week plus DTIC 1,000 mg/m2 once every 21 days was identified as the RP2D, demonstrating a favorable benefit-risk profile in a heavily pretreated population of adults with advanced LMS.

Metastatic Retroperitoneal Leiomyosarcoma: Case Report

Introduction: Leiomyosarcomas (LMS) are rare malignant neoplasms originating in smooth muscle, more common in women in their fifth and sixth decades of life. Inherent characteristics of the retroperitoneum allow LMS in this location to reach substantial proportions and present symptoms only in more advanced stages. Case report: A 37-year-old woman sought medical attention in July 2020 due to the growth of a painful, fixed mass in the left hemiabdomen that appeared six months earlier. The patient denied urinary or gastrointestinal alterations but reported an 8 kg weight loss in the last month. Computed tomography identified a lobulated, heterogeneous formation in the left flank measuring 8.5 cm, along with hepatic and pulmonary nodules. Subsequently, surgical resection of the lesion, nephroureterectomy, and hepatic biopsy were performed, confirming the diagnosis of LMS through anatomopathological and immunohistochemical analysis. After unsuccessful adjuvant chemotherapy, she progressed to multiple metastases and is currently undergoing palliative treatment. Conclusion: Detecting and diagnosing retroperitoneal LMS are challenging. Awareness of their aggressiveness, especially in young patients, is crucial to ensure personalized and early interventions, thereby improving the prognosis.

Molecular Heterogeneity in Leiomyosarcoma and Implications for Personalised Medicine.

Leiomyosarcoma (LMS) is one of the more common subtypes of soft tissue sarcomas (STS), accounting for about 20% of cases. Differences in anatomical location, risk of recurrence and histomorphological variants contribute to the substantial clinical heterogeneity in survival outcomes and therapy responses observed in patients. There is therefore a need to move away from the current one-size-fits-all treatment approach towards a personalised strategy tailored for individual patients. Over the past decade, tissue profiling studies have revealed key genomic features and an additional layer of molecular heterogeneity among patients, with potential utility for optimal risk stratification and biomarker-matched therapies. Furthermore, recent studies investigating intratumour heterogeneity and tumour evolution patterns in LMS suggest some key features that may need to be taken into consideration when designing treatment strategies and clinical trials. Moving forward, national and international collaborative efforts to aggregate expertise, data, resources and tools are needed to achieve a step change in improving patient survival outcomes in this disease of unmet need.

Validating the diagnostic accuracy of an MRI-based scoring system for differentiating benign uterine leiomyomas from leiomyosarcomas

ObjectiveUterine leiomyomas are the most common benign uterine tumors. They are difficult to distinguish from their malignant counterparts—smooth muscle tumors of unknown malignant potential (STUMP) and leiomyosarcoma. The purpose of...

Machine Learning Applied to Pre-Operative Computed-Tomography-Based Radiomic Features Can Accurately Differentiate Uterine Leiomyoma from Leiomyosarcoma: A Pilot Study.

The accurate discrimination of uterine leiomyosarcomas and leiomyomas in a pre-operative setting remains a current challenge. To date, the diagnosis is made by a pathologist on the excised tumor. The aim of this study was to develop a machine learning algorithm using radiomic data extracted from contrast-enhanced computed tomography (CECT) images that could accurately distinguish leiomyosarcomas from leiomyomas. Pre-operative CECT images from patients submitted to surgery with a histological diagnosis of leiomyoma or leiomyosarcoma were used for the region of interest identification and radiomic feature extraction. Feature extraction was conducted using the PyRadiomics library, and three feature selection methods combined with the general linear model (GLM), random forest (RF), and support vector machine (SVM) classifiers were built, trained, and tested for the binary classification task (malignant vs. benign). In parallel, radiologists assessed the diagnosis with or without clinical data. A total of 30 patients with leiomyosarcoma (mean age 59 years) and 35 patients with leiomyoma (mean age 48 years) were included in the study, comprising 30 and 51 lesions, respectively. Out of nine machine learning models, the three feature selection methods combined with the GLM and RF classifiers showed good performances, with predicted area under the curve (AUC), sensitivity, and specificity ranging from 0.78 to 0.97, from 0.78 to 1.00, and from 0.67 to 0.93, respectively, when compared to the results obtained from experienced radiologists when blinded to the clinical profile (AUC = 0.73 95%CI = 0.62-0.84), as well as when the clinical data were consulted (AUC = 0.75 95%CI = 0.65-0.85). CECT images integrated with radiomics have great potential in differentiating uterine leiomyomas from leiomyosarcomas. Such a tool can be used to mitigate the risks of eventual surgical spread in the case of leiomyosarcoma and allow for safer fertility-sparing treatment in patients with benign uterine lesions.

Mechanisms of sexual dimorphism in the pathogenesis of sarcomas

Sarcomas of non-genital organs affect women 1.5–3 times less often than men. The mechanism of such dimorphism is studied at various levels, mainly in the field of influence on the pathogenesis of sex hormones and their receptors, the effect of which is significantly related to the histogenesis of the tumor, its localization, the mechanism of malignant transformation and the stage of progression. Sex hormone receptors are often found in the early stages of tumor development and are lost during progression. At the same time, the expression of the same receptors in tumors of different histogenesis sometimes correlates with the opposite prognosis of the disease and sensitivity to hormonal therapy. For example, in uterine leiomyosarcomas, the expression of estrogen and androgen receptors correlates with a better prognosis and greater effectiveness of therapy, and in osteo- and fibrosarcomas, vice versa. Estrogens stimulate proliferation of osteosarcoma cells, and androgens that of rhabdomyosarcoma and small round cell tumor, which growth is inhibited by antiandrogens used in the treatment of prostate cancer. In this regard, when trying to include a hormonal component in a therapeutic complex, an individual study of the hormonal sensitivity of the tumor is necessary. One of the methodological approaches to this could be testing a culture of tumor cells from surgical material for sensitivity to agonists/antagonists of hormonal receptors separately and in combination with chemotherapy drugs.

Loss of the DNA Repair Gene RNase H2 Identifies a Unique Subset of DDR-Deficient Leiomyosarcomas.

Targeting the DNA damage response (DDR) pathway is an emerging therapeutic approach for leiomyosarcoma (LMS), and loss of RNase H2, a DDR pathway member, is a potentially actionable alteration for DDR-targeted treatments. Therefore, we designed a protein- and genomic-based RNase H2 screening assay to determine its prevalence and prognostic significance. Using a selective RNase H2 antibody on a pan-tumor microarray (TMA), RNase H2 loss was more common in LMS (11.5%, 9/78) than across all tumors (3.8%, 32/843). In a separate LMS cohort, RNase H2 deficiency was confirmed in uterine LMS (U-LMS, 21%, 23/108) and soft-tissue LMS (ST-LMS; 30%, 39/102). In the TCGA database, RNASEH2B homozygous deletions (HomDels) were found in 6% (5/80) of LMS cases, with a higher proportion in U-LMS (15%; 4/27) compared with ST-LMS (2%; 1/53). Using the SNiPDx targeted-NGS sequencing assay to detect biallelic loss of function in select DDR-related genes, we found RNASEH2B HomDels in 54% (19/35) of U-LMS cases with RNase H2 loss by IHC, and 7% (3/43) HomDels in RNase H2 intact cases. No RNASEH2B HomDels were detected in ST-LMS. In U-LMS patient cohort (n = 109), no significant overall survival difference was seen in patients with RNase H2 loss versus intact, or RNASEH2B HomDel (n = 12) versus Non-HomDel (n = 37). The overall diagnostic accuracy, sensitivity, and specificity of RNase H2 IHC for detecting RNA-SEH2B HomDels in U-LMS was 76%, 93%, and 71%, respectively, and it is being developed for future predictive biomarker driven clinical trials targeting DDR in U-LMS.

Roles of Matrix Metalloproteinases 2 and 9 in Uterine Leiomyosarcoma.

Uterine leiomyosarcoma (uLMS) is a rare, highly malignant, and invasive cancer, with early metastasis. Mismatch repair (MMR) proteins and matrix metalloproteinases (MMPs) are associated with the occurrence, proliferation, and invasion of most malignant cancers; however, their abnormal expression in uLMS remains poorly clarified. Immunohistochemistry was performed to assess MMR protein and MMP2/9 expression as well as Ki67 marker proliferation in benign and malignant uterine smooth muscle tumors. Data from 28 cases of uterine leiomyoma and 31 cases of uLMS were analyzed. Tumor tissues from patients with uLMS had higher expression levels of MMP2 (p<0.001), MMP9 (p<0.05), and Ki67 (p<0.001) than those from patients with uterine leiomyoma; MMR protein expression showed the opposite trend (p<0.05). uLMS proliferation and metastasis correlated positively with MMP2 (p=0.012 and 0.015, respectively) but negatively with MMP9 (p=0.021 and 0.04, respectively). MMR protein expression did not correlate with uLMS proliferation or metastasis (p>0.05). Expression levels of MMP2 and MMP9 were upregulated in malignant uLMS tumors when compared with those in benign uterine leiomyoma tumors. Increased MMP2 expression might promote uLMS invasion and migration. MMP9 overexpression might be related to uLMS occurrence; however, it protects against uLMS invasion and metastasis. MMP2 and MMP9 may be potential predictors of uLMS cell proliferation, metastasis, and prognosis. These findings could be helpful in developing new strategies for diagnosing and treating uLMS.

New treatment strategies for uterine sarcoma using secreted frizzled‑related proteins.

Secreted frizzled-related proteins (SFRPs) are involved in the development of various types of cancer and function by suppressing the Wnt signaling pathway. To elucidate the clinical implications of SFRPs in uterine sarcoma, SFRP expression levels and their effects on uterine leiomyosarcoma cells were examined. Immunostaining for SFRP4 was performed on uterine smooth muscle, uterine fibroid and uterine leiomyosarcoma tissues. Additionally, the effects of SFRP4 administration on cell viability, migration and adhesion were evaluated in uterine leiomyosarcoma SKN cells using the WST-1 assay (Roche Diagnostics) and the CytoSelect™ 24-well Cell Migration Assay Kit and the CytoSelect™ 48-well Cell Adhesion Assay Kit. The expression levels of SFRP4 in uterine leiomyosarcoma tissues were lower than those in normal smooth muscle and uterine fibroid tissues. In addition, SFRP4 suppressed the viability and migration, and increased the adhesion ability of uterine leiomyosarcoma cells compared with in the control group. In conclusion, SFRP4 may suppress the viability and migration, and enhance the adhesion of sarcoma cells. These results suggested that SFRP4 could be considered as a novel therapeutic target for uterine sarcoma.

Abstract 1766: CREBBP, NOTCH2 and GNASmutational profile in uterine sarcomas

Abstract Background: Uterine sarcomas (US) present clinical challenges due to their dynamic behavior and limited treatment options. Representing 1-3% of uterine cancer cases, these tumors exhibit rapid growth, high recurrence rates, and resistance to the standard treatments. The present study aimed to validate several Loss-of-function mutations (LOF), obtained by NGS analysis in the CREBBP, NOTCH2, and GNAS sequences, in US through Sanger sequencing. Methods: Twenty-five samples of US were collected between 2000 and 2015 for genomic DNA extraction. An initial genetic screening of the samples by NGS method was followed by Sanger sequencing validation. Bioinformatics analysis through SnapGene confirmed the results. Results: A c.4063G&amp;gt;A mutation was confirmed in uterine leiomyosarcomas (ULMS), in the both strands. Notable variations in the forward strand, such as a C&amp;gt;G substitution at position 38 of the alignment and a degenerate base S at position 113, differentiated ULMS from uterine sarcomas (US). Two ULMSs exhibited the highest substitution rates: one with 18 and another with 6 substitutions. Despite the absence of the c.5527T&amp;gt;C CREBBP mutation, ULMS displayed increased insertions and deletions. Assessing the NOTCH2 gene in US revealed a complex genetic landscape, with a unique SU-specific duplication in the forward strand. The reverse strand maintained high genetic stability. Mutation c.6094C&amp;gt;A was exclusive to one US sample. Notably, the c.7223T&amp;gt;A mutation in NOTCH2 was not identified. Shared mutations between ULMS and US suggest genomic similarities in these regions. In the GNAS analysis, the c.2381A&amp;gt;C mutation was not found. However, in the forward sequence of one US sample, a deletion at the expected substitution site was detected, suggesting a specific genetic alteration. The c.706G&amp;gt;A mutation was consistently present in sample ULMS, indicating genetic stability in this sample. US exhibited a G&amp;gt;C substitution in the reverse sequence, hinting at a unique pattern of genetic variation. These findings underscore the complexity of genetic alterations in these critical gene regions. Conclusion: Our analysis identified specific alterations in ULMS and US. ULMS showed the c.4063G&amp;gt;A CREBBP mutation and unique variations, while US had a specific c.6094C&amp;gt;A NOTCH2 mutation. The absence of the c.2381A&amp;gt;C GNAS mutation in both ULMS and US, along with distinct genetic patterns (c.706G&amp;gt;A in ULMS and G&amp;gt;C substitution in US), underscores significant mutational differences in these critical gene regions. These findings enhance our understanding of uterine sarcoma genetics, prompting further exploration for potential diagnosis, prognosis and therapeutic advancements. Citation Format: Laura Gonzalez dos Anjos, Giovanna Quevedo, Edmund Baracat, Katia C. Carvalho. CREBBP, NOTCH2 and GNASmutational profile in uterine sarcomas [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1766.

Abstract 1991: Leiomyosarcoma poly-aneuploid cancer cells form in response to chemotherapy, contribute to chemoresistance, and lead to higher rates of metastatic recurrence

Abstract Poly-aneuploid cancer cells (PACCs) or as also known as “giant cells”, are a treatment resistant stem cell-like cancer phenotype. PACCs have been identified in numerous cancer types, and their presence appears to play a significant role in chemoresistance and poor patient outcomes. PACCs employ a multitude of polyploidization programs to enter this transient state in response to stress. After removal of stress, PACCs give rise to non-PACC progeny through potential mechanisms of neosis or depolyploidization that maintain chemotherapeutic resistance. Leiomyosarcoma (LMS) is a difficult to treat sarcoma that grows in smooth muscle that often develops chemoresistance. Here we report the first description of PACCs in LMS cell culture, LMS xenografts, and LMS patient tumor microarrays. LMS cells treated (doxorubicin, docetaxel, and gemcitabine) in vitro and in vivo lead to the development of mononucleated and multinucleated polypoid cells as the predominant phenotype via polyploidization. Polyploidization mechanisms identified included endocycling, endomitosis, and cell-cell fusion. In vitro, LMS PACCs had a significant increase in size and DNA content as well as an increase in resistance to chemotherapy as compared to parents. LMS PACCs also repopulated the culture with non-PACC LMS progeny cells. The PACC progeny cells maintained a significantly decreased (p&amp;lt;0.0001) response to chemotherapy compared to parent cells. PACCs were also identified in clinical samples from patients with LMS. Twenty-nine percent of samples (N=289) contained abnormally large tumor cells and fifty-eight percent contained abnormal nuclei. A positive correlation was observed in patient tumor samples between PACCs in metastatic tumors and recurrence (p=0.0277) and survival (p=0.0009) than those patient tumors without PACCs. The high rate of functional loss of TP53 in LMS (&amp;gt;90%) may contribute to the ability of PACCs to form abnormal, multiple nuclei. We therefore transfected LMS PACCs to express TP53 and observed an increased apoptotic response. Additionally, combining functional TP53 expression with low doses of doxorubicin increases the apoptotic response of LMS cells, potentially by targeting PACCs. LMS PACCs may contribute to the lack of response in patients with LMS. Identifying therapeutic approaches that prevent or target LMS PACCs, including TP53 replacement, may improve response to chemotherapy and improve outcomes for patients. Citation Format: Ryan Kennington, Gareth Mitchell, Emily Payne, Niraja Bhachech, Jonathan A. Fletcher, Ting Liu, Matt van de Rijn, Sarah Amend, Kenneth J. Pienta, Joshua D. Schiffman, Lisa M. Abegglen. Leiomyosarcoma poly-aneuploid cancer cells form in response to chemotherapy, contribute to chemoresistance, and lead to higher rates of metastatic recurrence [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1991.