Well-differentiated liposarcomas and dedifferentiated liposarcomas: Systemic treatment options for two sibling neoplasms.

Well-differentiated liposarcomas (WDLPS) and dedifferentiated liposarcomas (DDLPS) account for 60 % of all liposarcomas, reflecting the heterogeneity of this type of sarcoma. Genetically, both types of liposarcomas are characterized by the amplification of MDM2 and CDK4 genes, which indicates an important molecular event with diagnostic and therapeutic relevance. In both localized WDLPS and DDLPS of the retroperitoneum and the extremities, between 25 % and 30 % of patients have local or distant recurrence, even when perioperatively treated, with clear margins present. The systemic treatment of WDLPS and DDLPS remains a challenge, with anthracyclines as the gold standard for first-line treatment. Several regimens have been tested with modest results regarding their efficacy. Herein we discuss the systemic treatment options for WDLPS and DDLPS and review their reported clinical efficacy results.

MDM2-p53 in liposarcoma: The need for targeted therapies with novel mechanisms of action.

Well-differentiated and dedifferentiated liposarcomas (WDLPS and DDLPS) are rare tumors that arise from lipocytes in soft tissue. There is a high unmet need in patients with these liposarcomas given poor outcomes, particularly for DDLPS. WDLPS and DDLPS share important genetic and histological characteristics - most notably, the amplification of the 2 genes MDM2 and CDK4. Both genes are considered oncogenes because of their ability to shut down tumor suppressor pathways. There are multiple therapeutic approaches that aim to target MDM2 and CDK4 activity for the purpose of restoring intrinsic tumor suppressor cellular response and terminating oncogenesis. However, current understanding of the molecular mechanisms involved in WDLPS and DDLPS pathology is limited. In recent years, significant efforts have been made to refine and implement targeted therapy for this patient population. The use of patient-derived cell and tumor xenograft models has been an important tool for recapitulating WDLPS and DDLPS biology. These models also offer valuable insights for drug development and drug combination studies. Here we offer a review of the current understanding of WDLPS and DDLPS biology and its therapeutic implications.

Pharmacological reactivation of p53 in the era of precision anticancer medicine.

p53, which is encoded by the most frequently mutated gene in cancer, TP53, is an attractive target for novel cancer therapies. Despite major challenges associated with this approach, several compounds that either augment the activity of wild-type p53 or restore all, or some, of the wild-type functions to p53 mutants are currently being explored. In wild-type TP53 cancer cells, p53 function is often abrogated by overexpression of the negative regulator MDM2, and agents that disrupt p53-MDM2 binding can trigger a robust p53 response, albeit potentially with induction of p53 activity in non-malignant cells. In TP53-mutant cancer cells, compounds that promote the refolding of missense mutant p53 or the translational readthrough of nonsense mutant TP53 might elicit potent cell death. Some of these compounds have been, or are being, tested in clinical trials involving patients with various types of cancer. Nonetheless, no p53-targeting drug has so far been approved for clinical use. Advances in our understanding of p53 biology provide some clues as to the underlying reasons for the variable clinical activity of p53-restoring therapies seen thus far. In this Review, we discuss the intricate interactions between p53 and its cellular and microenvironmental contexts and factors that can influence p53's activity. We also propose several strategies for improving the clinical efficacy of these agents through the complex perspective of p53 functionality.

[Prognostic model for assessing the human glioma cell malignancy grade based on MDM2, MELK, SOX2, CDK4, DR5 and OCT4 gene expression]. / Prognosticheskaya model' dlya otsenki stepeni zlokachestvennosti kul'tury kletok gliomy cheloveka na osnovanii issledovaniya ekspressii paneli genov MDM2, MELK, SOX2, CDK4, DR5 i OCT4.

Glioma cell cultures are used in basic researches of tumor processes, personalized medicine for selecting treatment regimens depending on individual characteristics of patients and pharmacology for assessing the effectiveness of chemotherapy. Suppression of glioma culture growth without reduction of malignancy grade is common. Drug cancellation may be followed by substitution of precursor cells by more malignant clones. Therefore, analysis of culture cell malignancy grade is important. In the future, intraoperative analysis of glioma cell malignancy grade can be used to select individual therapy. OBJECTIVE: We analyzed the relationship between expression of marker genes TUBB3, CD133, CDK4, CDK6, CIRBP, DR4, DR5, EGFR, FGFR, FSHR, GDNF, GFAP, L1CAM, LEF1, MAP2, MDM2, MELK, NANOG, NOTCH2, OCT4, OLIG2, PDGFRA, PDGFA, PDGFB and SOX2 and glioma cell malignancy grade, as well as created appropriate prognostic model. MATERIAL AND METHODS: We analyzed expression of 25 marker genes in 22 samples of human glioma cultures using quantitative real-time PCR. Statistical analysis was performed using the IBM SPSS Statistics 26.0 software. We used the Kolmogorov-Smirnov and Shapiro-Wilk tests to assess distribution normality. Nonparametric Jonckheere-Terpstra and Spearman tests were applied. RESULTS: We obtained a prognostic model for assessing the grade III and IV glioma cell malignancy based on expression of marker genes MDM2, MELK, SOX2, CDK4, DR5 and OCT4. Predictive accuracy was 83% (Akaike information criterion -55.125).

MDM2-mediated Inhibitory Effect of Arsenic Trioxide on Small Cell Lung Cancer Cell Line by Degrading Mutant p53.

INTRODUCTION: Small cell lung cancer (SCLC) is featured by a high TP53 mutant rate. Our previous research found that arsenic trioxide (As2O3) could significantly inhibit the growth and metastasis of SCLC. Studies have shown that the degradation of mutant p53 mediated by murine double minute 2 (MDM2) can be induced by As2O3, which probably contributes to the inhibition of SCLC, but the detailed mechanism is still unclear. We aimed to testify that As2O3 can inhibit the growth of SCLC cells by degrading mutant p53 protein via binding to MDM2. METHODS: CCK-8 assay, cell cycle analysis, and western blot of apoptosis markers were used to evaluate the inhibitory effect of As2O3 on NCI-H446 cells (containing mutant p53) and NCI-H1299 cells (p53 null). The effects of As2O3 on p53 and its downstream proteins were identified by western blot using mut-p53-knockdown and overexpressed cell models. MDM2-knockdown cell models were constructed, and western blot, co-IP of mut-p53, and ubiquitin were carried out to explore the mediating effect of MDM2 in As2O3 induced mut-p53 degradation. RESULTS: As2O3 inhibited proliferation and induced cell cycle arrest and apoptosis of SCLC cells in a dose- and timedependent manner. After mut-p53 knockdown or overexpressed, the inhibitory effect of As2O3 was dampened or enhanced. Additionally, As2O3-induced mut-p53 ubiquitination was significantly weakened after MDM2 knockdown. CONCLUSION: As2O3 could inhibit SCLC cells by inhibiting proliferation and inducing cell cycle arrest and apoptosis. These inhibitory effects were achieved at least in part by upregulating MDM2, which, in turn, promotes ubiquitination and degradation of mut-p53.

Recent Advancements in the Discovery of MDM2/MDM2-p53 Interaction Inhibitors for the Treatment of Cancer.

Discovery of MDM2 and MDM2-p53 interaction inhibitors changed the direction of anticancer research as it is involved in about 50% of cancer cases globally. Not only the inhibition of MDM2 but also its interaction with p53 proved to be an effective strategy in anticancer drug design and development. Various molecules of natural as well as synthetic origin have been reported to possess excellent MDM2 inhibitory potential. The present review discusses the pathophysiology of the MDM2-p53 interaction loop and MDM2/MDM2-p53 interaction inhibitors from literature covering recent patents. Focus has also been put on characteristic features of the active site of the target and its desired interactions with the currently FDA-approved inhibitor. The designing approach of previously reported MDM2/MDM2-p53 interaction inhibitors, their SAR studies, in silico studies, and the biological efficacy of various inhibitors from natural as well as synthetic origins are also elaborated. An attempt is made to cover recently patented MDM2/MDM2- p53 interaction inhibitors.

New targeted treatments for advanced sarcomas.

PURPOSE OF REVIEW: The purpose of this review is to provide the rationale and results behind recent clinical trials regarding molecular-targeted agents for advanced sarcomas. RECENT FINDINGS: Tazemetostat, a first-in-class EZH2 inhibitor, was approved to treat advanced epithelioid sarcoma. In synovial sarcoma, the interaction between pathognomonic SS18-SSX fusion protein and the BAF complex has brought insight in using BRD9 inhibitors as a treatment based on synthetic lethality. MDM2 overexpression is an important mechanism to suppress p53 function, and MDM2 gene amplification is pathognomonic in well differentiated and dedifferentiated liposarcoma. Two MDM2 inhibitors, milademetan and BI907828, have both reached the optimal dosing and have shown promising efficacy in MDM2-amplified liposarcoma. Late-stage pivotal studies are ongoing for both of these MDM2 inhibitors. The co-amplification of CDK4 and MDM2 in liposarcoma also provided a rationale for CDK4/6 inhibitors as a potential therapy. Selinexor, an exportin-1 inhibitor, has shown single-agent activity in dedifferentiated liposarcoma and action in gastrointestinal stromal tumour in combination with imatinib. Lastly, a new formulation of mTOR inhibitor, nab-sirolimus, was recently approved for perivascular epithelioid cell tumour (PEComa). SUMMARY: Molecular-guided precision medicine holds a bright future in bringing more active treatments for advanced sarcoma patients.

A First-in-Human Phase I Study of Milademetan, an MDM2 Inhibitor, in Patients With Advanced Liposarcoma, Solid Tumors, or Lymphomas.

PURPOSE: This study evaluated the safety, pharmacokinetics, pharmacodynamics, and preliminary efficacy of milademetan, a small-molecule murine double minute-2 (MDM2) inhibitor, in patients with advanced cancers. PATIENTS AND METHODS: In this first-in-human phase I study, patients with advanced solid tumors or lymphomas received milademetan orally once daily as extended/continuous (days 1-21 or 1-28 every 28 days) or intermittent (days 1-7, or days 1-3 and 15-17 every 28 days) schedules. The primary objective was to determine the recommended phase II dose and schedule. Secondary objectives included tumor response according to standard evaluation criteria. Predefined analyses by tumor type were performed. Safety and efficacy analyses included all patients who received milademetan. RESULTS: Between July 2013 and August 2018, 107 patients were enrolled and received milademetan. The most common grade 3/4 drug-related adverse events were thrombocytopenia (29.0%), neutropenia (15.0%), and anemia (13.1%). Respective rates at the recommended dose and schedule (260 mg once daily on days 1-3 and 15-17 every 28 days, ie, 3/14 days) were 15.0%, 5.0%, and 0%. Across all cohorts (N = 107), the disease control rate was 45.8% (95% CI, 36.1 to 55.7) and median progression-free survival was 4.0 months (95% CI, 3.4 to 5.7). In the subgroup with dedifferentiated liposarcomas, the disease control rate and median progression-free survival were 58.5% (95% CI, 44.1 to 71.9) and 7.2 months overall (n = 53), and 62.0% (95% CI, 35.4 to 84.8) and 7.4 months with the recommended intermittent schedule (n = 16), respectively. CONCLUSION: An intermittent dosing schedule of 3/14 days of milademetan mitigates dose-limiting hematologic abnormalities while maintaining efficacy. Notable single-agent activity with milademetan in dedifferentiated liposarcomas has prompted a randomized phase III trial (MANTRA).

High-Throughput Screening Identifies Idasanutlin as a Resensitizing Drug for Venetoclax-Resistant Neuroblastoma Cells.

Neuroblastoma tumors frequently overexpress the anti-apoptotic protein B-cell lymphoma/leukemia 2 (BCL-2). We previously showed that treating BCL-2-dependent neuroblastoma cells with the BCL-2 inhibitor venetoclax results in apoptosis, but unfortunately partial therapy resistance is observed. The current study describes the identification of drugs capable of resensitizing venetoclax-resistant neuroblastoma cells to venetoclax. To examine these effects, venetoclax resistance was induced in BCL-2-dependent neuroblastoma cell lines KCNR and SJNB12 by continuous exposure to high venetoclax concentrations. Non-resistant and venetoclax-resistant neuroblastoma cell lines were exposed to a 209-compound library in the absence and presence of venetoclax to identify compounds that were more effective in the venetoclax-resistant cell lines under venetoclax pressure. Top hits were further validated in combination with venetoclax using BCL-2-dependent neuroblastoma model systems. Overall, high-throughput drug screening identified the MDM2 inhibitor idasanutlin as a promising resensitizing agent for venetoclax-resistant neuroblastoma cell lines. Idasanutlin treatment induced BAX-mediated apoptosis in venetoclax-resistant neuroblastoma cells in the presence of venetoclax, whereas it caused p21-mediated growth arrest in control cells. In vivo combination treatment showed tumor regression and superior efficacy over single-agent therapies in a BCL-2-dependent neuroblastoma cell line xenograft and a patient-derived xenograft. However, xenografts less dependent on BCL-2 were not sensitive to venetoclax-idasanutlin combination therapy. This study demonstrates that idasanutlin can overcome resistance to the BCL-2 inhibitor venetoclax in preclinical neuroblastoma model systems, which supports clinical development of a treatment strategy combining the two therapies.

Primary colonic liposarcomatosis: report of a case with review of literature

The colon is a rare site of occurrence of liposarcoma, as either the primary site or by secondary involvement from a retroperitoneal liposarcoma. Liposarcomatosis denotes simultaneous occurrence of multiple liposarcomas. There are only 17 cases of primary colonic liposarcoma reported in the English literature­one of which was primary colonic liposarcomatosis. We depict the second case of primary colonic liposarcomatosis in a 57-year-old female who presented with abdominal swelling and pain. On exploratory laparotomy, two large masses were seen arising from the wall of the right colon along with multiple smaller masses attached to the colon. Right hemicolectomy with en bloc excision of the masses was performed along with hysterectomy and pelvic floor repair. Macroscopically, multiple exophytic masses and one endophytic mass were identified. The exophytic masses were of variable size and were found to hang from the colon by a thin pedicle simulating variable-sized appendices epiploicae. Histopathologically, the lesions showed the morphology of well-differentiated liposarcoma. This appears to be a case of primary colonic liposarcomatosis. There is only one other similar case reported in the English literature, to the best of our knowledge.