Liposarcoma Research Articles

Characterizing the transformation and diagnosis of atypical lipomatous tumors to dedifferentiated liposarcoma: Single-institutional outcomes.

e23560 Background: Atypical lipomatous tumor (ALT) is a locally aggressive, benign adipocytic tissue mass with risk of transformation into dedifferentiated liposarcoma (DDLS), a mixed-grade, non-lipogenic tumor with increased risk for metastasis and mortality. Studies have evaluated the dedifferentiation rate of DDLS but seldom report the methodology of obtaining their diagnosis, which is crucial due to their heterogeneous architecture and relatively low core needle biopsy (CNB) accuracy. We included a longitudinal cohort of ALT/DDLS patients characterizing how and when patients received their diagnoses. Methods: 168 patients diagnosed with ALT-only (n = 129), DDLS-only (n = 22), or both (n = 17) were included. Among DDLS patients, the presence of a prior ALT diagnosis along with time between their ALT and DDLS diagnosis was measured. Histology, location, results, and methods of each diagnosis were recorded including, CNB, surgical resection, or both. Disease-specific survival (DSS) and recurrence free-survival (RFS) were calculated with univariate/multivariate analysis for risk factors. Results: Among patients who received a diagnosis with CNB consistent with ALT, 7 were subsequently diagnosed with DDLS after surgical resection, representing 4.8% of ALT patients. Mean time between diagnoses was 2.3 months (STD 2.0). 5 (3.4%) patients were diagnosed with a DDLS recurrence after initial ALT diagnosis confirmed with CNB and surgical resection. Median time between diagnoses was 37.0 months (IQR 16.0, 63.0). 5 (3.4%) had tumors with a heterogeneous composition on initial surgical resection, described as an ALT with dedifferentiated components. 22 DDLS patients had no prior ALT diagnosis. 9 were diagnosed from both CNB and surgical resection, and 13 were diagnosed from surgical resection directly after clinical suspicion and imaging concerning for sarcoma. DSS in the DDLS was significantly lower than ALT-only DSS (p < 0.0001). There was no significant difference in RFS. Conclusions: DDLS may arise after an extended period of time after ALT resection or simultaneously with an ALT diagnosis. Due to its varied diagnostic timeline and appearance, caution is advised when evaluating and treating ALT. [Table: see text]

Mixed liposarcoma: A study of socioeconomic and demographic factors.

e23527 Background: Mixed Liposarcoma (LS) is an extremely rare subtype of LS, with characteristics often spanning 2 or more of the other LS subtypes such as myxoid, round cell, or well-differentiated LS. To date, the cytologic features of this uncommon tumor has yet to be described. Analyzing trends in diagnoses may produce valuable information about its epidemiology. The National Cancer Database (NCDB) was analyzed to uncover the demographic factors in patients diagnosed with mixed LS. Methods: A retrospective cohort study from 2004 to 2020 was conducted using the NCDB. 199 patients were found with a histologically confirmed diagnosis of mixed LS (ICD-8855-3). Race, gender, Hispanic origin, type of treatment facility, insurance coverage, and distance from patient residence to treatment facility were analyzed via descriptive statistics, and trends in incidence were interpreted using regression analysis. Results: The majority of patients were white (89%) and non-Hispanic (83%) with a relatively equal split of males (56%) and females (44%). The most common primary site of mixed LS was the retroperitoneum (72%), and the frequency of diagnosis decreased from 2004 to 2020 (R2 = 0.4568). Patients were treated at academic/research programs (45%), comprehensive community cancer programs (25%) and integrated network cancer programs (18%) that were generally located in the Middle Atlantic (19%), South Atlantic (18%), and East North Central (16%). The two primary payers at diagnosis include private insurance/managed care (45%) and Medicare (43%). Most patients were from counties in metro areas with a population of at least 1 million (57%) followed by metro counties with a population of 250,000 to 1 million (18%). The largest median household income quartile was $74,063 or more (38%), followed by $46,227 - $57,856 (22%). Most patients had a Charlson-Deyo Score of 0 (83%) with a NCDB analytic stage of either I (28%), III (26%), or not applicable (21%). Conclusions: To the best of our knowledge this NCDB analysis on mixed LS is the first of its kind and therefore addresses a significant knowledge gap. Most patients tend to be white and non-Hispanic. Mixed LS most commonly is found in the retroperitoneum, which is similar to case reports. We found that mixed LS patients have a relatively high household income, most often live in high populated metro areas, and are most frequently treated at academic/research programs. These findings are significant because these socioeconomic factors have not been noted before in literature. Further examination of these demographic and socioeconomic factors is required to understand how they impact treatment, diagnosis of, and survival of patients with mixed LS.

SU2C-SARC032: A randomized trial of neoadjuvant RT and surgery with or without pembrolizumab for soft tissue sarcoma.

11504 Background: Surgery & radiation therapy (RT) yield high local control rates for soft tissue sarcoma (STS) of the extremity and limb girdle. However, patients (pts) with high-grade stage III STS are at significant risk for developing metastasis. Median survival for pts with metastatic STS is < 2 years. SARC028 (NCT02301039) evaluated the efficacy of pembrolizumab (pembro) for metastatic STS, showing 20% and 8.7% response rates in undifferentiated pleomorphic sarcoma (UPS) and pleomorphic/dedifferentiated liposarcoma (LPS), respectively. We hypothesized that neoadjuvant pembro with concurrent RT followed by surgery and adjuvant pembro for stage III UPS, including myxofibrosarcoma, or LPS would stimulate an anti-tumor immune response to eliminate micrometastatic disease & improve disease-free survival (DFS). SU2C-SARC032 (NCT03092323) is a multi-institutional, international, randomized phase 2 trial evaluating the safety and efficacy of adding pembro to standard of care (SOC) RT & surgery for pts with stage III UPS or LPS. Methods: Pts aged > 12 yo with stage III (FNCLCC grade 2 or 3) UPS or LPS of the extremity and limb girdle were enrolled. Pts were randomized (1:1, stratified by grade) to neoadjuvant RT (50 Gy/25 fx) then surgery (SOC arm) or neoadjuvant pembro and RT then surgery & adjuvant pembro (EXP arm). Pembro was given 200 mg IV Q3 wk for 3 doses (before, during & after RT) & up to 14 adjuvant cycles. The primary endpoint was 2-yr DFS. Secondary endpoints included local recurrence-free survival (LRFS), distant disease-free survival (DDFS), & overall survival (OS). Target enrollment of 126 evaluable patients (max 144 total) provided 80% power (1-sided α = 0.05) to distinguish between a null hypothesis of 50% 2-yr DFS rate & alternative hypothesis of 75% 2-yr DFS rate by log-rank test, with initial analysis at 45 DFS events. Cox models were stratified by grade; primary analysis was a one-sided stratified log-rank test. Results: Between July 2017-November 2023, 143 patients were enrolled, predominantly with UPS (85%) & grade 3 (64%) histology. Median follow-up for alive patients is 24.1 mo. DFS in the EXP arm is significantly higher than the SOC arm (p = 0.023; HR 0.57, 90% CI: 0.35, 0.91). Estimated 2-yr DFS is 53% (90% CI: 43, 66%) for SOC vs 70% (90% CI: 61, 81%) for EXP arm. Currently, there is no statistically significant difference in LRFS (HR 0.55, 95% CI: 0.21, 1.42), DDFS (HR 0.57, 95% CI: 0.32, 1.01), or OS (HR 0.39, 95% CI: 0.14, 1.12). Pts with grade 3 sarcomas had improved DFS with pembro (HR 0.47, 95% CI: 0.25, 0.89), but no difference in DFS was observed in grade 2 tumors (HR 1.21, 95% CI: 0.35, 4.18). The proportion of patients with grade 3+ adverse events was significantly higher in EXP (52%) vs SOC arm (26%) (p = 0.002). Conclusions: Theaddition of neoadjuvant & adjuvant pembro to RT and surgery significantly improves DFS for pts with stage III UPS and LPS of the extremity and limb girdle. Clinical trial information: NCT03092323 .

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 .

Sclerosing well-differentiated liposarcoma: two diagnostically challenging mimicker cases and a literature review.

Liposarcoma is a malignant soft tissue tumor with several subtypes, the most common of which is well-differentiated liposarcoma (WDL) or atypical lipomatous tumor (ALT). WDL/ALTs are further divided into three histological subtypes, including lipoma-like, sclerosing, andinflammatory. While the majority of these tumors are predominantly fatty, the sclerosing variant demonstrates diverse histologic and radiographic characteristics, including variable amounts of fibrosis and fat. Because of this histological variability and relative rarity, the sclerosing WDL/ALT can present diagnostic dilemmas. We present two cases of sclerosing WDL/ALT, both of which demonstrated high degrees of fibrosis and a paucity of fat, mimicking desmoid fibromatosis and other fibrotic soft tissue tumors. Thus, it is important for radiologists to be aware of the subtypes of liposarcoma and their unique characteristics, and to consider sclerosing WDL/ALT in cases of fibrotic soft tissue tumors.

New targeted therapies in liposarcoma: state of art and future perspectives.

Liposarcomas (LPSs) represent the most common soft tissue sarcoma (STS) subtype, and exhibit distinct clinical molecular features according to histological subgroup. Chemotherapy (ChT), and in particular anthracycline-based schedules, still remains the standard of treatment for all LPS forms. However, given the increasing knowledge gained throughout last years about LPS molecular biology and their genomic profiling, new therapeutic alternatives with targeted drugs are now to be considered. In this review, we will highlight most promising ongoing and published clinical trials regarding targeted therapies in LPSs and provide some insights about future approaches and possible new treatment options for this rare disease. Among all the explored targets, mouse double minute 2 homolog amplification and CKD4-Rb axis inhibition seem to be the most promising target in well differentiated/dedifferentiated LPS subtype. On the other hand, myxoid LPS is known to have a particular sensitivity for trabectedin, which acts like a targeted drug due to its specific action on cellular DNA. In addition to these, multiple other strategies are now being evaluated in LPSs, including the administration of immune-checkpoint inhibitors (ICIs) and 'new-old' cytotoxic agents, such as cabazitaxel, in a continuously growing scenario. Although preliminary, results of recently published and ongoing examined clinical trials will hopefully be translated in clinical practice in the next future, leading the way to future research in this rare disease.

An overview on liposarcoma subtypes: Genetic alterations and recent advances in therapeutic strategies.

Liposarcoma (LPS) is a rare malignancy of adipocytic differentiation. According to World Health Organization classification, LPS comprises of four principle subtypes Atypical lipomatous tumor/Well-differentiated liposarcoma (ATL/WDLPS), Dedifferentiated liposarcoma (WDLPS), Myxoid liposarcoma (MLPS), and Pleomorphic liposarcoma (PLPS). Each subtype can develop at any location and shows distinct clinical behavior and treatment sensitivity. ATL/ WDLPS subtype has a higher incidence rate, low recurrence, and is insensitive to radiation and chemotherapy. DDLPS is the focal progression of WDLPS, which is aggressive and highly metastasizing. MLPS is sensitive to radiation and chemotherapy, with a higher recurrence rate and metastasis. PLPS subtype is highly metastasizing, has a poor prognosis, and exhibiting higher recurrence rate. Initial histological analysis provides information for the characterization of LPS subtypes', further molecular and genetic analysis provides certain subtype specifications, such as gene amplifications and gene fusions. Such molecular genetic alterations will be useful as therapeutic targets in various cancers, including the LPS subtypes. A wide range of novel therapeutic agents based on genetic alterations that aim to target LPS subtypes specifically are under investigation. This review summarizes the LPS subtype classification, their molecular genetic characteristics, and the implications of genetic alterations in therapeutics.

Outcome of patients with liposarcoma: A retrospective review over 12 ​Years in a single center

BackgroundLiposarcoma is the most common soft tissue sarcoma, which comprises around 20% of soft tissue sarcoma. While diverse therapeutic approaches exist for liposarcoma, the primary goal remains the achievement of effective local disease control. Wide resection of liposarcoma is the cornerstone of treatment. Radiotherapy is often employed as an adjuvant measure to enhance the local disease control. At Hospital Kuala Lumpur, the treatment protocol includes R0 resection and followed by adjuvant radiotherapy. This study aims to review the demographic characteristic of liposarcoma patients and evaluate the efficacy of their treatment based on the treatment protocol. Method and materialThis is a retrospective cohort study. A total of 72 patients (male/female ​= ​43/29) were included in this study. Recorded parameters included the histologic subtype, tumor location, treatment modality, resection margin, radiotherapy status, and occurrences of local recurrence and metastasis. ResultHistopathological examination revealed a varied spectrum of liposarcoma subtypes, with the predominant subtype being atypical lipomatous tumor (n ​= ​35), followed by myxoid liposarcoma (n ​= ​32), two cases of dedifferentiated liposarcoma, and three cases of pleomorphic liposarcoma. Of these patients, 69 underwent resection, while three necessitated amputations. Total 62 achieving negative and 10 cases had R1 margins. Adjuvant radiotherapy was administered in 58 cases. Overall, the local recurrence was observed in only six cases. ConclusionThis study emphasizes that achieving R0 resection is the fundamental approach in the treatment of liposarcoma and is able to minimize the risk of local recurrence.

Abstract CT066: Phase 1 study of MDM2 antagonist ASTX295 in patients with solid tumors with wild-type TP53

Abstract Background: ASTX295 is a novel small molecule antagonist of human Murine Double Minute 2 (MDM2), which tightly regulates the level and activity of the p53 tumor suppressor. To minimize potential thrombocytopenia previously seen with antagonism of this target, ASTX295 was designed to have a short half-life (t1/2) with decreased bone marrow (BM) exposure. ASTX295 has proapoptotic and tumor growth inhibitory activity in preclinical cancer (CA) models. We report here the safety and preliminary efficacy of the phase 1 and dose expansion portions of Study ASTX295-01. Methods: ASTX295-01 is a first-in-human, open-label, multicenter, phase 1/2 study to assess safety, pharmacokinetics (PK), pharmacodynamics (PD), and preliminary clinical activity of ASTX295 (NCT03975387). Eligible patients (advanced solid tumors with Wild-Type [WT] TP53, ECOG PS 0-2, adequate organ and bone marrow function, etc.) had oral administration of ASTX295 starting at a daily dose of 15 mg. Dose escalation was by standard 3 + 3 with cohorts testing multiple regimens. Safety was assessed by CTCAE and disease was assessed by RECIST 1.1. Safety and efficacy and dosing recommendations were overseen by the Data Safety Review Committee. Results:83 subjects were enrolled in over 14 cohorts, evaluating daily (QD) and intermittent dosing regimens and the effect of food. The mean age of subjects on study was 60.1 year, 56.9 were male, with 2.94 (0-15) prior chemotherapy regimens. For PK exposure, the total weekly AUC for 400 mg QD and 660 twice a week (BIW) are similar. The median tmax is 3 hours and mean t1/2 is 4-6 hours. PD demonstrates p53 pathway modulation. Nausea, vomiting, diarrhea, and fatigue were dose limiting. RP2D regimens were 660 mg BIW and 400 mg QD and these regimens were expanded with a total of 25 additional subjects. The most common treatment related AEs for both regimens were nausea, diarrhea, and vomiting at 76.2%,76.2%, and 33.3% respectively, for daily and 71.4%, 47.6%, and 33.3%, for intermittent. Grade 3 GI AEs were reported in 14.3% of subjects in the daily cohort vs 9.5% in the intermittent; none had Grade ≥ 4. One subject had grade 2 thrombocytopenia. Based on decreased incidence and duration of GI AEs, 660 mg BIW was selected as the RP2D.Multiple objective responses were seen, including 1 subject with non-small cell lung CA and 3 subjects with liposarcoma (LPS), a tumor with frequent MDM2 amplification. For LPS the ORR is 7.9% (de-differentiated 7.7%, well differentiated 8.0%), with a PFS of 7.95 and 9.66 months respectively, along with a 16-week disease control rate of 69.2% and 72.0%. Five subjects with GBM were enrolled, 4 with MDM2 amplification, 3 of whom showed evidence of tumor regression, with one subject remaining on study for > 34 cycles. Conclusion:ASTX295 was well tolerated at doses producing p53 pathway modulation with manageable toxicities, notably avoiding significant thrombocytopenia. Preliminary single agent efficacy was observed in heavily pretreated subjects across multiple solid tumor types with WT TP53. Citation Format: Ecaterina E. Dumbrava, Fabio M. Iwamoto, Mark Agulnik, Mohammed Milhem, Anthony W. Tolcher, Rashmi Chugh, Michael J. Demeure, Alain Mita, Kurt Demel, Mark Diamond, Beloo Mirakhur, Laksmi Wilson, Aram Oganesian, Danna Chan, Harold N. Keer, Jason Taylor, Martin J. Sims, Andrea Biondo, Simone Jueliger, Alexander Spira. Phase 1 study of MDM2 antagonist ASTX295 in patients with solid tumors with wild-type TP53 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr CT066.

Recurrent dedifferentiated retroperitoneal liposarcoma complicating pregnancy

Retroperitoneal liposarcoma is an uncommon tumor both in the pregnant and nonpregnant state. Its exact incidence is unknown because of its rarity. Due to its propensity for local recurrence, prognosis depends on histologic subtype and negative margins of resection. Surgery remains the mainstay of treatment, and timing is critical in terms of finding a surgically resectable lesion while balancing fetal risks. This report describes tumor recurrence in a pregnancy with a prior history of surgery for an atypical lipomatous tumor presenting as a retroperitoneal mass. After discussion with the multidisciplinary team, as well as with the patient’s consent, the plan was to defer surgery until 34 weeks, followed by scheduled tumor removal 2 weeks postpartum. She delivered abdominally to a baby girl with a good outcome. Histopathology showed dedifferentiated liposarcoma with a positive tumor margin. The patient has survived at 6-month follow-up and completed four cycles of chemotherapy with doxorubicin, ifosfamide, and mesna. However, surveillance imaging again showed tumor recurrence.

Atypical lipoma of the right piriformis muscle: a case report and review of the literature

BackgroundPiriformis muscle mass is rare, which is particular for intrapiriformis lipoma. Thus far, only 11 cases of piriformis muscle mass have been reported in the English literature. Herein, we encountered one patient with intrapiriformis lipoma who was initially misdiagnosed.Case presentationThe patient is a 50-year-old Chinese man. He complained of osphyalgia, right buttock pain, and radiating pain from the right buttock to the back of the right leg. Both ultrasound and magnetic resonance imaging demonstrated a cyst-like mass in the right piriformis muscle. Ultrasonography-guided aspiration was performed on this patient first, but failed. He was then recommended to undergo mass resection and neurolysis of sciatic nerve. Surprisingly, final histology revealed the diagnosis of intrapiriformis lipoma. The patient exhibited significant relief of symptoms 3 days post-surgery.ConclusionDiagnosis and differential diagnosis of radicular pain are potentially challenging but necessary. Atypical lipoma is prone to be misdiagnosed, especially in rare sites. It is notable for clinicians to be aware of the presence of intrapiriformis lipoma to avoid misdiagnosis and inappropriate treatment.

High expression of apoptosis-related LMNB2 predicts an unfavorable outcome: A potential prognostic biomarker for liposarcoma

Liposarcoma (LPS) is the most prevalent soft-tissue sarcoma and the second most common malignant mesenchymal sarcoma. Molecular markers have proven instrumental in guiding the diagnosis, prognosis, and treatment strategies for LPS patients. Identifying potential therapeutic targets is essential for developing effective intervention strategies for LPS. LMNB2, an apoptosis-related gene, exhibits associations with various tumors. Therefore, exploring the feasibility of LMNB2 as a prognostic biomarker for LPS is crucial. After screening for differentially expressed genes (DEGs), which were analyzed by GEO2R, 14 apoptosis-related genes were obtained by overlapping DEGs from the GSE21122 and GSE159659 datasets. SPSS software was used for univariate analysis. Receiver operating characteristic curves were constructed by GraphPad software to compare the expression of LMNB2 between LPS and normal tissues. Kaplan–Meier curves were generated to verify the correlation between LMNB2 expression and survival time. GeneMANIA and STRING were used to construct LMNB2-related gene-gene and protein–protein interaction networks. Hiplot software facilitated function and pathway enrichment analysis to determine the potential mechanism of LMNB2-mediated LPS progression. CIBERSORT was used to evaluate the correlation between LMNB2 expression and immune cell infiltration. The expression level of LMNB2 was significantly higher in LPS, and the high expression of LMNB2 was significantly related to poor prognosis in LPS patients. Further analysis indicated that LMNB2 was mainly involved in “senescence” and “apoptosis,” further confirming its role in regulating the occurrence and development of LPS by modulating the cell cycle progression and apoptosis. This study demonstrates that the elevated expression of LMNB2 is significantly associated with poor prognostic outcomes in LPS, suggesting that LMNB2 holds high potential as a new biomarker for LPS. This study is designed to elucidate the potential mechanism of LMNB2-mediated LPS progression, with the prospect of improving therapeutic development by identifying LMNB2 as a promising prognostic biomarker for LPS.

Abstract 604: Targeting casein kinase 1 alpha (CK1 alpha) and transcriptional CDKs (CDK7/9) in human liposarcomas

Abstract Introduction: Liposarcomas (LPS) are rare mesenchymal cell malignancies of adipocytic origin that are diagnosed in more than 3500 patients in the US each year. The two most common subtypes, well-differentiated LPS (WDLPS) and dedifferentiated LPS (DDLPS), are characterized by extrachromosomal DNA amplifications harboring the MDM2 (100%) and CDK4 (90+%) genes, generally with wild type TP53. Management of metastatic or surgically unresectable LPS remains purely palliative. Recent clinical trials targeting MDM2 or CDK4/6 with small-molecule inhibitors have shown promise but have been hampered by dose-limiting toxicities. The development of new therapeutics is greatly needed to improve outcomes for patients with LPS. Results: To identify unique liposarcoma-specific vulnerabilities, we screened multiple human LPS cell lines for transcriptional CDK expression and found high levels of CDK7 and CDK9. We demonstrate that CDK9 inhibitors suppress LPS cell growth and induce apoptosis by decreasing MDM2 levels while inducing expression of p53. To enhance p53 activation in these cells, we screened for expression of known regulators of p53, including CK1α, whose inhibition has previously been shown to activate p53. We demonstrate that LPS cells express CK1α and that the cytotoxic effects of CDK9 inhibitors are enhanced upon CK1α depletion. These data led us to examine combined targeting of CK1α and CDK9 in LPS with the novel agent BTX-A51, which has previously been shown to inhibit CK1α, CDK9, as well as CDK7 with nanomolar efficacy in AML models. BTX-A51 potently reduces expression of MDM2 with marked induction of p53, resulting in profound apoptosis of LPS cells. Through CRISPR/Cas9-mediated p53 knockout, we establish that BTX-A51-mediated apoptosis is primarily p53-dependent. However, BTX-A51 also reduces expression of MCL1 and primes LPS cell lines and primary LPS cells for BIM-induced apoptosis, as demonstrated by BH3 profiling. Importantly, preliminary in vivo data in an LPS patient-derived xenograft model reveal that BTX-A51 is well-tolerated with tumor growth inhibition. Conclusions: Our results suggest that BTX-A51 has potent preclinical efficacy in treating LPS, primarily through inhibition of CK1α and CDK9. Future mechanistic studies will further clarify mechanisms of BTX-A51-mediated apoptosis, as well as the contribution of CDK7 inhibition to anti-tumor activity. Our data justify a planned clinical trial that will evaluate the efficacy of BTX-A51 in patients with advanced WDLPS or DDLPS. Citation Format: Renyan Liu, Nicole L. Solimini, Patrick Bhola, Timothy B. Branigan, Jie Hao, Xin Wang, Roshen Alharthi, Michael Yorsz, Shaili Soni, Cing-siang Hu, Irit Snir-Alkalay, Prafulla Gokhale, Anthony Letai, Yinon Yinon Ben-Neriah, George D. Demetri, Geoffrey I. Shapiro. Targeting casein kinase 1 alpha (CK1 alpha) and transcriptional CDKs (CDK7/9) in human liposarcomas [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 604.

Abstract 3365: Reliable detection of potentially therapeutically actionable ecDNA using clinical-grade NGS in a large pan-cancer cohort

Abstract Background Focal high-level oncogene amplifications (FH-amp) (e.g., MYC, EGFR) frequently occur on extrachromosomal DNA (ecDNA), highly transcribed units of circular non-chromosomal DNA. FH-amp on ecDNA promote intra-tumoral heterogeneity, resistance to therapies, and poor prognosis. Recently, a Phase 1 clinical trial exploring ecDNA-directed treatments has begun. However, to date, bioinformatic detection of ecDNA has relied on whole-genome sequencing data, and no standard method exists to detect ecDNA on targeted NGS. We thus sought to explore the feasibility of detecting ecDNA in a large cohort of patients with solid tumors sequenced with the targeted NGS panel, MSK-IMPACT, and describe the pan-cancer prevalence of oncogenes amplified on ecDNA. Methods We utilized a novel bioinformatic ecDNA-diagnostic algorithm, ECHO, to determine the presence of oncogene FH-amp on ecDNA (including HSR) vs. chromosomal in clinical-grade NGS data. 72,651 tumor samples profiled by MSK-IMPACT were queried for high level oncogene FH-amp (AR, CCNE1, CDK4/6, EGFR, FGFR1-4, KRAS, MDM2, MDM4, MET, MYC, MYCL, and MYCN) above a fold-change of three, and subsequently annotated with ECHO. Patients with concomitant oncogenic driver mutations or fusions (e.g., EGFR L858R, EML4-ALK) were excluded based on the hypothesis that they might be mutually exclusive with oncogene FH-amp. Results FH-amp of any above listed oncogene were found in 3065 (4.2%) samples. Cancer types with frequent FH-amp without concomitant driver alterations were liposarcoma (LPS) (61% FH-amp; 43% were ecDNA+), glioblastoma (GBM) (22%; 72%), gastroesophageal adenocarcinoma (GE AD) (10%; 57%) squamous cell lung cancer (7%; 18%), and breast cancer (BRCA) (7%; 23%). Among tumors with oncogene FH-amp, GBM and GE AD had high frequencies of ecDNA+ FH-amp of EGFR (39% and 15% of all EGFR ecDNA+). LPS had the highest frequency of ecDNA+ FH-amp of CDK4 (64%), followed by GBM (15%). The majority of ecDNA+ FGFR1 and FGFR2 FH-amp were in BRCA (75% and 47%). EGFR in GBM and EGFR or FGFR2 in GE AD were ecDNA+ in more than 90% of patients, while CDK4 in LPS and FGFR1 in BRCA were ecDNA+ in 45% and 39% respectively.Evaluation the relationship between ecDNA+ by ECHO and amp FC range showed higher ecDNA+ in samples with higher level amp (FC > 5; 58% ecDNA+) compared to lower level amp (FC 4~5; 12%, FC 3~4; 6% ecDNA+). Conclusions A novel ecDNA clinical diagnostic tool, ECHO, was successfully applied to a large clinical cohort of patients enriched for actionable oncogene amplifications sequenced with MSK-IMPACT. The results demonstrate that detection of ecDNA using clinical-grade NGS assays is feasible and that key oncogene FH-amp on ecDNA (e.g., EGFR, FGFR2) are common in select tumor types. ECHO may be developed as a clinical trial device to prospectively identify patients with oncogene ecDNA+ FH-amp for clinical testing of ecDNA-directed therapies. Citation Format: Matteo Repetto, Klaus Wagner, Shalabh Suman, Peter Krein, Pavitra Rao, Maria Arcila, Christian Hassig, Mark Donoghue, Alexander Drilon, Michael Berger. Reliable detection of potentially therapeutically actionable ecDNA using clinical-grade NGS in a large pan-cancer cohort [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 3365.

Abstract 2088: Targeting transcriptional factor IWS1 as a potential treatment of advanced dedifferentiated liposarcoma

Abstract Introduction. Surgery remains the only curative treatment for patients with liposarcoma (LPS). The translation of novel therapies has been hampered, and there has been no significant improvement in prognosis for 30 years. Our recent findings demonstrate that IWS1, a transcription elongation and alternative splicing factor, is elevated in dedifferentiated LPS (ddLPS) patient tumor samples and is associated with worse survival and a shorter time to relapse in ddLPS. In this study, we present preliminary results on a novel treatment for advanced ddLPS: an IWS1 inhibitor, serving as a way to discover a spliceosome as a novel therapeutic target. Methods. Utilizing computer-aided, structure-based virtual screening approaches, we identified a class of compounds that exhibited inhibitory potential. A subset of FDA-approved drugs was evaluated by molecular docking calculations, and compounds with the highest calculated theoretical potency were selected for further analysis. To assess the ability of specific compounds to disrupt IWS1/Spt6 binding, Co-immunoprecipitation (Co-IP) experiments on ddLPS cell line Lipo863 were conducted. Transwell invasion and migration assays were performed to evaluate the effect of the drug candidate on the metastatic potential of cells. Additionally, to evaluate the impact of IWS1 inhibition on spheroid formation, a matrigel extracellular matrix scaffold was employed. Results. Through virtual screening, we identified a class of compounds characterized by a specific chemical pattern featuring a tricyclic fused-ring structure. This class of compounds includes the well-known FDA-approved drug Ketotifen, an antihistamine and mast cell stabilizer. Co-immunoprecipitation of IWS1/Spt6 complex after 48-hour treatment with Ketotifen showed a decrease of over 50% of the isolated complex. Migration and invasion of the ddLPS cell line, Lipo863, were reduced in a dose-dependent manner by 18-44% and 17-52%, respectively, when treated with Ketotifen, without affecting cell viability. In a 3D model, a 14-day treatment of Ketotifen significantly reduced spheroid formation, confirming its impact on tumor growth and cell proliferation. Conclusion. Ketotifen effectively disrupted IWS1/Spt6 complex in vitro. Importantly, it did not affect cell viability while reducing the migratory and invasive potential of ddLPS. The dose-dependent effect of Ketotifen suggests that there may be an optimal in vivo concentration to prevent cells from invading nearby structures and/or metastasizing. We are currently testing the ability of these compounds in preclinical mouse models of ddLPS. Citation Format: Marina Goryunova, Yiran He, Nipin Sp, Elizaveta K. Titerina, Sayumi Tahara, Carson Karakis, Alessandro La Ferlita, Michael Sorkin, Alex Kim, Hua Zhu, Christopher M. Hadad, Raphael E. Pollock, Joal D. Beane. Targeting transcriptional factor IWS1 as a potential treatment of advanced dedifferentiated liposarcoma [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 2088.

[Translated article] Comparative study of deep lipomas and atypical lipomatous tumours: Malignancy risk factors

Background and objectivesThe diagnostic suspicion of an atypical lipomatous tumour (ALT) is difficult. The aim of this study is to delve into the most controversial diagnostic aspects of the subject. Material and methodObservational, longitudinal and retrospective study of a series of 96 deep adipose tumours (75 lipomas and 21 TLA) from 2006 to 2016: demographic, clinical, imaging and pathological variables were analysed and compared, as well as other variables related to treatment and oncological outcomes of the patients. A descriptive analysis of the collected variables was performed for the statistical study. To evaluate the potential predictor variables of malignancy, a multivariate logistic regression analysis was performed, including those that were statistically significant in the univariate analysis. ResultsOlder age at diagnosis, lower limb location and larger size were significantly more frequent in ALTs. MRI findings showed no statistically significant differences between the two groups. In multivariate analysis, the same clinical variables were confirmed as predictors of malignancy. In the ROC curve, an optimal cut-off point of 134.0mm was used as a predictor of malignancy. ConclusionsAdvanced age, location in the lower limbs and larger size are risk factors for malignancy in the differential diagnosis of deep lipomas and atypical lipomatous tumours. No radiological variable on MRI reached significance as a predictor of malignancy in our series.

A comprehensive analysis of CD47 expression in various histological subtypes of soft tissue sarcoma: exploring novel opportunities for macrophage-directed treatments

PurposeThe CD47 molecule, often referred to as the “do not eat me” signal, is frequently overexpressed in tumor cells. This signaling pathway limits phagocytosis by macrophages. Our objective was to determine CD47 abundance in various soft tissue sarcomas (STS) to investigate whether it could serve as a potential evasion mechanism for tumor cells. Additionally, we aimed to assess the prognostic value of CD47 expression by examining its association with different clinicopathological factors. This study aimed to elucidate the significance of CD47 in the context of emerging anti-tumor targeting approaches.MethodsIn this retrospective study, formalin-fixed paraffine-embedded (FFPE) tumor tissues of 55 treatment-naïve patients were evaluated by immunohistochemistry for the abundance of CD47 molecule on tumor cells. The categorization of CD47 positivity was as follows: 0 (no staining of tumor cells), 1 + (less than 1/3 of tumor area positive), 2 + (between 1/3 and 2/3 of tumor area positive), and 3 + (more than 2/3 of tumor area positive for CD47). Next, we compared CD47 abundance between different tumor grades (G1–3). We used Kaplan–Meier survival curves with log-rank test to analyze the differences in survival between patients with different CD47 expression. Moreover, we performed Cox proportional hazards regression model to evaluate the clinical significance of CD47.ResultsCD47 is widely prevalent across distinct STS subtypes. More than 80% of high grade undifferentiated pleiomorphic sarcoma (UPS), 70% of myxofibrosarcoma (MFS) and more than 60% of liposarcoma (LPS) samples displayed a pattern of moderate-to-diffuse positivity. This phenomenon remains consistent regardless of the tumor grade. However, there was a tendency for higher CD47 expression levels in the G3 group compared to the combined G1 + G2 groups when all LPS, MFS, and UPS were analyzed together. No significant associations were observed between CD47 abundance, death, and metastatic status. Additionally, high CD47 expression was associated with a statistically significant increase in progression-free survival in the studied cohort of patients.ConclusionThis study highlights the potential of the CD47 molecule as a promising immunotherapeutic target in STS, particularly given its elevated expression levels in diverse sarcoma types. Our data showed a notable trend linking CD47 expression to tumor grade, while also suggesting an interesting correlation between enhanced abundance of CD47 expression and a reduced hazard risk of disease progression. Although these findings shed light on different roles of CD47 in STS, further research is crucial to assess its potential in clinical settings.

Surgical Management of a Large Well-Differentiated Liposarcoma in the Supraclavicular Fossa: A Case Report.

Background: Liposarcomas originating in the supraclavicular fossa are exceptionally rare, with only a few documented cases in the medical literature. Methods: We present a unique case involving a remarkably large indolent, atypical lipomatous tumor or well-differentiated liposarcoma situated in the right supraclavicular region, measuring 18 cm × 18 cm × 17 cm. To our knowledge, this represents the largest liposarcoma found in the supraclavicular fossa reported in the literature. This unique case highlights the effective management of a remarkably large supraclavicular liposarcoma through complete surgical resection. Result and Conclusion: Our findings further support the existing consensus that complete surgical removal is often curative for well-differentiated liposarcoma.

Differential Diagnosis of Lipomatous Tumors Using 18F-Fluorodeoxygulcose Positron Emission Tomography/Computed Tomography: A Retrospective Observational Study.

Lipomatous tumors, including lipomas, atypical lipomatous tumors (ALTs), myxoid liposarcomas (MLs), and dedifferentiated liposarcomas (DLs), are often diagnosed using magnetic resonance imaging (MRI). Differential diagnosis of lipomas and ALTs by MRI is often challenging. 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) has recently been used for the diagnosis and evaluation of tumor staging and recurrence of soft tissue tumors. The maximum standardized uptake value (SUVmax) is positively associated with malignant grade in several cancers. This study aimed to evaluate SUVmax of 18F-FDG PET/CT in the differential diagnosis of lipomatous tumors. Patients who underwent 18F-FDG PET/CT for the diagnosis of lipomatous tumors between January 2013 and September 2021 were included in the study. Patients with lipomatous tumors, confirmed by pathological diagnosis or surgical specimens, were evaluated for lipomatous tumor SUVmax. This study included 44 patients with lipomas (n=19), ALTs (n=12), MLs (n=9), and DLs (n=4). The mean SUVmax of lipomas, ALTs, MLs, and DLs was 0.99±1.41, 1.92±0.95, 5.21±4.94, and 9.29±1.43, respectively. Lipomas showed a significantly lower SUVmax than did ALTs, MLs, and DLs (p<0.05). ALTs demonstrated a significantly lower SUVmax than did MLs and DLs (p<0.05). No significant differences were observed between MLs and DLs. Lipomas or ALTs had a significantly lower SUVmax than lipomatous sarcomas. Lipomas had a significantly lower SUVmax than ALTs, aiding in their preoperative differentiation. 18F-FDG-PET/CT could serve as a potent tool for the differential diagnosis of lipomatous tumors.

Radiologic-histopathologic correlation of fatty island sign with fat necrosis in atypical lipomatous tumor and lipoma

This study aimed to assess the imaging features of atypical lipomatous tumors (ALTs) and lipoma with fat necrosis. This study included patients with histopathologically proven fat necrosis within adipocytic tumors who underwent preoperative imaging. Magnetic resonance imaging (MRI) and/or computer tomography (CT) findings of fat necrosis associated with lipomatous tumors were retrospectively reviewed, emphasizing the "fatty island sign (FIS)." FISs were defined as well-demarcated, focal fat-containing areas surrounded by more thickened septa compared with other intratumoral septa. Imaging findings of FIS were compared between ALT and lipoma. Fat necrosis was histopathologically confirmed in 17 patients (6 ALTs and 11 lipomas). Among them, 18 FISs were observed in 10 lesions (59%). Multiple FISs within a lesion were observed in 4 (40%) patients. The median maximum diameter of the FISs was 37 mm. Hypointense areas within FISs relative to the subcutaneous fat on T1- and T2-weighted images were observed in 8 (80%) and 9 (90%), respectively, whereas hyperintense areas within FISs on fat-suppressed T2-weighted images were observed in 2 (20%). Nonfatty solid components within FISs were observed in 2 (20%). On CT, increased fat attenuation and pure fat attenuation within FISs were observed in 6 (86%) and 1 (14%), respectively. The imaging findings of FIS were not significantly different between ALT and lipoma. FISs were observed in 59% of the histologically proven ALT and lipoma patients with fat necrosis. The hypointense areas relative to the subcutaneous fat on T1- and T2-weighted images and increased fat attenuation on CT were usually observed within FISs.