AXL is a potential therapeutic target in dedifferentiated and pleomorphic liposarcomas

AXL as immune regulator and therapeutic target in Acute Myeloid Leukemia: from current progress to novel strategies

Until recently, treatment options for patients diagnosed with Acute Myeloid Leukemia (AML) were limited and predominantly relied on various combinations, dosages, or schedules of traditional chemotherapeutic agents. Patients with advanced age, relapsed/refractory disease or comorbidities were often left without effective treatment options. Novel advances in the understanding of leukemogenesis at the molecular and genetic levels, alongside recent progress in drug development, have resulted in the emergence of novel therapeutic agents and strategies for AML patients. Among these innovations, the receptor tyrosine kinase AXL has been established as a promising therapeutic target for AML. AXL is a key regulator of several cellular functions, including epithelial-to-mesenchymal transition in tumor cells, immune regulation, apoptosis, angiogenesis and the development of chemoresistance. Clinical studies of AXL inhibitors, as single agents and in combination therapy, have demonstrated promising efficacy in treating AML. Additionally, novel AXL-targeted therapies, such as AXL-specific antibodies or antibody fragments, present potential solutions to overcome the limitations associated with traditional small-molecule AXL inhibitors or multikinase inhibitors. This review provides a comprehensive overview of the structure and biological functions of AXL under normal physiological conditions, including its role in immune regulation. We also summarize AXL's involvement in cancer, with a specific emphasis on its role in the pathogenesis of AML, its contribution to immune evasion and drug resistance. Moreover, we discuss the AXL inhibitors currently undergoing (pre)clinical evaluation for the treatment of AML.

Evaluation of the Role of AXL in Fusion-positive Pediatric Rhabdomyosarcoma Identifies the Small-molecule Inhibitor Bemcentinib (BGB324) as Potent Chemosensitizer

Rhabdomyosarcoma (RMS) is a highly aggressive pediatric cancer with features of skeletal muscle differentiation. More than 80% of the high-risk patients ultimately fail to respond to chemotherapy treatment, leading to limited therapeutic options and dismal prognostic rates. The lack of response and subsequent tumor recurrence is driven in part by stem cell-like cells, the tumor subpopulation that is enriched after treatment, and characterized by expression of the AXL receptor tyrosine kinase (AXL). AXL mediates survival, migration, and therapy resistance in several cancer types; however, its function in RMS remains unclear. In this study, we investigated the role of AXL in RMS tumorigenesis, migration, and chemotherapy response, and whether targeting of AXL with small-molecule inhibitors could potentiate the efficacy of chemotherapy. We show that AXL is expressed in a heterogeneous manner in patient-derived xenografts (PDX), primary cultures and cell line models of RMS, consistent with its stem cell-state selectivity. By generating a CRISPR/Cas9 AXL knock-out and overexpressing models, we show that AXL contributes to the migratory phenotype of RMS, but not to chemotherapy resistance. Instead, pharmacologic blockade with the AXL inhibitors bemcentinib (BGB324), cabozantinib and NPS-1034 rapidly killed RMS cells in an AXL-independent manner and augmented the efficacy of the chemotherapeutics vincristine and cyclophosphamide. In vivo administration of the combination of bemcentinib and vincristine exerted strong antitumoral activity in a rapidly progressing PDX mouse model, significantly reducing tumor burden compared with single-agent treatment. Collectively, our data identify bemcentinib as a promising drug to improve chemotherapy efficacy in patients with RMS.

PDE3A Is a Highly Expressed Therapy Target in Myxoid Liposarcoma

Liposarcomas (LPSs) are a heterogeneous group of malignancies that arise from adipose tissue. Although LPSs are among the most common soft-tissue sarcoma subtypes, precision medicine treatments are not currently available. To discover LPS-subtype-specific therapy targets, we investigated RNA sequenced transcriptomes of 131 clinical LPS tissue samples and compared the data with a transcriptome database that contained 20,218 samples from 95 healthy tissues and 106 cancerous tissue types. The identified genes were referred to the NCATS BioPlanet library with Enrichr to analyze upregulated signaling pathways. PDE3A protein expression was investigated with immunohistochemistry in 181 LPS samples, and PDE3A and SLFN12 mRNA expression with RT-qPCR were investigated in 63 LPS samples. Immunoblotting and cell viability assays were used to study LPS cell lines and their sensitivity to PDE3A modulators. We identified 97, 247, and 37 subtype-specific, highly expressed genes in dedifferentiated, myxoid, and pleomorphic LPS subtypes, respectively. Signaling pathway analysis revealed a highly activated hedgehog signaling pathway in dedifferentiated LPS, phospholipase c mediated cascade and insulin signaling in myxoid LPS, and pathways associated with cell proliferation in pleomorphic LPS. We discovered a strong association between high PDE3A expression and myxoid LPS, particularly in high-grade tumors. Moreover, myxoid LPS samples showed elevated expression levels of SLFN12 mRNA. In addition, PDE3A- and SLFN12-coexpressing LPS cell lines SA4 and GOT3 were sensitive to PDE3A modulators. Our results indicate that PDE3A modulators are promising drugs to treat myxoid LPS. Further studies are required to develop these drugs for clinical use.

Systemic Therapy in Advanced Pleomorphic Liposarcoma: a Comprehensive Review

OPINION STATEMENT

The therapeutic approach of pleomorphic liposarcoma (PLPS), a rare high-grade subgroup of soft tissue sarcoma, is commonly extrapolated from the management of other LPS subtypes. Only published retrospective data on PLPS currently serve as a guide for oncologists without clear recommendations or specific guidelines. In the advanced setting, specific systemic therapy such as eribulin and trabectedin showed promising activity in comparison to conventional therapy (doxorubicin- and gemcitabine-based protocols), which currently remains the current standard of care at initial stages of the disease. The better understanding of soft tissue sarcoma (STS) pathophysiology and disease course has led to the development of adapted clinical trial designs for rare STS histotypes with specific treatment approach.

Gas6/AXL pathway: immunological landscape and therapeutic potential

Cancer is a disease with ecological and evolutionary unity, which seriously affects the survival and quality of human beings. Currently, many reports have suggested Gas6 plays an important role in cancer. Binding of gas6 to TAM receptors is associated with the carcinogenetic mechanisms of multiple malignancies, such as in breast cancer, chronic lymphocytic leukemia, non-small cell lung cancer, melanoma, prostate cancer, etc., and shortened overall survival. It is accepted that the Gas6/TAM pathway can promote the malignant transformation of various types of cancer cells. Gas6 has the highest affinity for Axl, an important member of the TAM receptor family. Knockdown of the TAM receptors Axl significantly affects cell cycle progression in tumor cells. Interestingly, Gas6 also has an essential function in the tumor microenvironment. The Gas6/AXL pathway regulates angiogenesis, immune-related molecular markers and the secretion of certain cytokines in the tumor microenvironment, and also modulates the functions of a variety of immune cells. In addition, evidence suggests that the Gas6/AXL pathway is involved in tumor therapy resistance. Recently, multiple studies have begun to explore in depth the importance of the Gas6/AXL pathway as a potential tumor therapeutic target as well as its broad promise in immunotherapy; therefore, a timely review of the characteristics of the Gas6/AXL pathway and its value in tumor treatment strategies is warranted. This comprehensive review assessed the roles of Gas6 and AXL receptors and their associated pathways in carcinogenesis and cancer progression, summarized the impact of Gas6/AXL on the tumor microenvironment, and highlighted the recent research progress on the relationship between Gas6/AXL and cancer drug resistance.

Decreased Gas6 and sAxl Plasma Levels Are Associated with Hair Loss in COVID-19 Survivors

Post-acute conditions after coronavirus disease 2019 (COVID-19) are quite common, although the underlying pathogenetic mechanisms leading to these conditions are not yet completely understood. In this prospective observational study, we aimed to test the hypothesis that Growth Arrest-Specific 6 (Gas6) and its soluble receptors, Axl (sAxl) and MerTK (sMer), might be implicated. A total of 263 subjects underwent a structured clinical evaluation one year after their hospital discharge for COVID-19, and they consented to donate a blood sample to measure their circulating Gas6, sAxl, and sMer levels. A total of 98 (37.3%) post-COVID-19 subjects complained of at least one residual physical symptom one year after their hospital discharge. Univariate analysis revealed that sAxl was marginally associated with residual symptoms, but at the level of logistic regression analysis, only the diffusing capacity of the lungs for carbon monoxide (DLCO) (OR 0.98, CI 95%: 0.96–0.99; p = 0.007) and the female sex (OR 2.49, CI 95%: 1.45–4.28; p = 0.001) were independently associated with long-lasting symptoms. A total of 69 (26.2%) subjects had hair loss. At the level of univariate analysis, Gas6, sAxl, DLCO, and the female gender were associated with its development. In a logistic regression analysis model, Gas6 (OR 0.96, CI 95%: 0.92–0.99; p = 0.015) and sAxl (OR 0.98, CI 95%; 0.97–1.0; p = 0.014), along with the female sex (OR 6.58, CI 95%: 3.39–12.78; p = 0.0001), were independent predictors of hair loss. Decreased levels of Gas6 and sAxl were associated with a history of hair loss following COVID-19. This was resolved spontaneously in most patients, although 23.7% complained of persistent hair loss one year after hospital discharge.

The First-In-Class Anti-AXL×CD3ε Pronectin™-Based Bispecific T-Cell Engager Is Active in Preclinical Models of Human Soft Tissue and Bone Sarcomas

Sarcomas are heterogeneous malignancies with limited therapeutic options and a poor prognosis. We developed an innovative immunotherapeutic agent, a first-in-class Pronectin™-based Bispecific T-Cell Engager (pAXL×CD3ε), for the targeting of AXL, a TAM family tyrosine kinase receptor highly expressed in sarcomas. AXL expression was first analyzed by flow cytometry, qRT-PCR, and Western blot on a panel of sarcoma cell lines. The T-cell-mediated pAXL×CD3ε cytotoxicity against sarcoma cells was investigated by flow cytometry, luminescence assay, and fluorescent microscopy imaging. The activation and degranulation of T cells induced by pAXL×CD3ε were evaluated by flow cytometry. The antitumor activity induced by pAXL×CD3ε in combination with trabectedin was also investigated. In vivo activity studies of pAXL×CD3ε were performed in immunocompromised mice (NSG), engrafted with human sarcoma cells and reconstituted with human peripheral blood mononuclear cells from healthy donors. Most sarcoma cells showed high expression of AXL. pAXL×CD3ε triggered T-lymphocyte activation and induced dose-dependent T-cell-mediated cytotoxicity. The combination of pAXL×CD3ε with trabectedin increased cytotoxicity. pAXL×CD3ε inhibited the in vivo growth of human sarcoma xenografts, increasing the survival of treated mice. Our data demonstrate the antitumor efficacy of pAXL×CD3ε against sarcoma cells, providing a translational framework for the clinical development of pAXL×CD3ε in the treatment of human sarcomas, aggressive and still-incurable malignancies.

Enapotamab Vedotin, an AXL-Specific Antibody-Drug Conjugate, Demonstrates Antitumor Efficacy in Patient-Derived Xenograft Models of Soft Tissue Sarcoma

Doxorubicin (doxo) remains the standard of care for patients with advanced soft tissue sarcoma (STS), even though response rates to doxo are only around 14% to 18%. We evaluated enapotamab vedotin (EnaV), an AXL-specific antibody-drug conjugate (ADC), in a panel of STS patient-derived xenografts (PDX). Eight models representing multiple STS subtypes were selected from our STS PDX platform (n = 45) by AXL immunostaining on archived passages. Models were expanded by unilateral transplantation of tumor tissue into the left flank of 20 NMRI nu/nu mice. Once tumors were established, mice were randomized into an EnaV treatment group, or a group treated with isotype control ADC. Treatment efficacy was assessed by tumor volume evaluation, survival analysis, and histological evaluation of tumors, and associated with AXL expression. EnaV demonstrated significant tumor growth delay, regression, and/or prolonged survival compared to isotype control ADC in 5/8 STS PDX models investigated. Experimental passages of responding models were all found positive for AXL at varying levels, but no linear relationship could be identified between the level of expression and level of response to EnaV. One model was found negative for AXL on experimental passage and did not respond to EnaV. This study provides a preclinical rationale for the evaluation of AXL-targeting ADCs in the treatment of AXL-expressing sarcomas.

Preclinical Development of ADCT-601, a Novel Pyrrolobenzodiazepine Dimer-based Antibody-drug Conjugate Targeting AXL-expressing Cancers

AXL, a tyrosine kinase receptor that is overexpressed in many solid and hematologic malignancies, facilitates cancer progression and is associated with poor clinical outcomes. Importantly, drug-induced expression of AXL results in resistance to conventional chemotherapy and targeted therapies. Together with its presence on multiple cell types in the tumor immune microenvironment, these features make it an attractive therapeutic target for AXL-expressing malignancies. ADCT-601 (mipasetamab uzoptirine) is an AXL-targeted antibody-drug conjugate (ADC) comprising a humanized anti-AXL antibody site specifically conjugated using GlycoConnect technology to PL1601, which contains HydraSpace, a Val-Ala cleavable linker and the potent pyrrolobenzodiazepine (PBD) dimer cytotoxin SG3199. This study aimed to validate the ADCT-601 mode of action and evaluate its efficacy in vitro and in vivo, as well as its tolerability and pharmacokinetics. ADCT-601 bound to both soluble and membranous AXL, and was rapidly internalized by AXL-expressing tumor cells, allowing release of PBD dimer, DNA interstrand cross-linking, and subsequent cell killing. In vivo, ADCT-601 had potent and durable antitumor activity in a wide variety of human cancer xenograft mouse models, including patient-derived xenograft models with heterogeneous AXL expression where ADCT-601 antitumor activity was markedly superior to an auristatin-based comparator ADC. Notably, ADCT-601 had antitumor activity in a monomethyl auristatin E-resistant lung-cancer model and synergized with the PARP inhibitor olaparib in a BRCA1-mutated ovarian cancer model. ADCT-601 was well tolerated at doses of up to 6 mg/kg and showed excellent stability in vivo. These preclinical results warrant further evaluation of ADCT-601 in the clinic.

Potential of Stem Cells and CART as a Potential Polytherapy for Small Cell Lung Cancer

Despite the increasing urgency of the problem of treating small cell lung cancer (SCLC), information on the causes of its development is fragmentary. There is no complete understanding of the features of antitumor immunity and the role of the microenvironment in the development of SCLC resistance. This impedes the development of new methods for the diagnosis and treatment of SCLC. Lung cancer and chronic obstructive pulmonary disease (COPD) have common pathogenetic factors. COPD is a risk factor for lung cancer including SCLC. Therefore, the search for effective approaches to prevention, diagnosis, and treatment of SCLC in patients with COPD is an urgent task. This review provides information on the etiology and pathogenesis of SCLC, analyses the effectiveness of current treatment options, and critically evaluates the potential of chimeric antigen receptor T cells therapy (CART therapy) in SCLC. Moreover, we discuss potential links between lung cancer and COPD and the role of endothelium in the development of COPD. Finally, we propose a new approach for increasing the efficacy of CART therapy in SCLC.

OPCML Exerts Antitumor Effects in Cholangiocarcinoma via AXL/STAT3 Inactivation and Rho GTPase Down-regulation

BACKGROUND/AIM

Opioid-binding protein/cell adhesion molecule-like (OPCML) plays a crucial role in the suppression of tumor progression in several cancer types. Nevertheless, the association between OPCML functions and cholangiocarcinoma (CCA) progression remains unknown. We aimed to investigate biological functions of OPCML and related signaling pathways in CCA cell lines.

MATERIALS AND METHODS

Methylation status and ectopic expression of OPCML were determined in CCA cell lines using methylation-specific polymerase chain reaction and pcDNA3.1+/C-(K)DYK-OPCML, respectively. Cell proliferation, migration and invasion were investigated.

RESULTS

OPCML was found to be epigenetically silenced by DNA methylation. Ectopic expression of OPCML inhibited CCA proliferation by inducing apoptosis via AXL receptor tyrosine kinase/signal transducer and activator of transcription 3 (AXL/STAT3) inactivation. It also suppressed cell migration and invasion via down-regulation of Rho GTPases, ras homolog family member A (RHOA), Rac family small GTPase 1 (RAC1) and cell division cycle 42 (CDC42).

CONCLUSION

We are the first to unravel the antitumor effects and the related signaling pathways of OPCML in CCA. The loss of OPCML expression due to promoter hypermethylation can cause a decrease in cell death but increase in cell migration and invasion, which may at least in part contribute to CCA progression.

AXL Inhibition Enhances MEK Inhibitor Sensitivity in Malignant Peripheral Nerve Sheath Tumors

Dysregulation of the receptor tyrosine kinase AXL is known to promote cancer cell growth and survival in many sarcomas, including the rare subtype, malignant peripheral nerve sheath tumors (MPNST). MPNSTs are largely chemoresistant and carry a poor prognosis. AXL is an attractive potential therapeutic target, as it is aberrantly expressed, and its activation may be an early event in MPNST. However, the effect of AXL inhibition on MPNST development and progression is not known. Here, we investigated the role of AXL in MPNST development and the effects of AXL and MEK1/2 co-inhibition on MPNSTs. We used western blotting to examine AXL expression and activation in MPNST cell lines. We analyzed the effects of exogenous growth arrest-specific 6 (GAS6) expression on downstream signaling and the proliferation, migration, and invasion of MPNST cells. The effect of AXL knockdown with or without mitogen-activated protein kinase (MAPK) inhibition on downstream signal transduction and tumorigenesis was also examined in vivo and in vitro. We found that AXL knockdown increased MAPK pathway signaling. This compensation, in turn, abrogated the antitumorigenic effects linked to AXL knockdown in vivo. AXL knockdown, combined with pharmacological MEK inhibition, reduced the proliferation and increased the apoptosis of MPNST cells both in vitro and in vivo. The pharmacological co-inhibition of AXL and MEK1/2 reduced MPNST volumes. Together these findings suggest that AXL inhibition enhances the sensitivity of MPNST to other small molecule inhibitors. We conclude that combination therapy with AXL inhibitor may be a therapeutic option for MPNST.

A dual MET/AXL small-molecule inhibitor exerts efficacy against gastric carcinoma through killing cancer cells as well as modulating tumor microenvironment

The receptor tyrosine kinases MET and AXL have been implicated in tumorigenesis and aggressiveness of multiple malignancies. We performed this study to evaluate the antitumor impact of LY2801653, a dual MET and AXL inhibitor on gastric cancer and to elucidate the underlying mechanisms. In the present study, tissue microarrays containing gastric cancer tissues were stained with MET and AXL antibodies, which showed the prognostic values of MET and AXL. Administration of LY2801653 inhibited cell proliferation, migration, epithelial‐mesenchymal transition, induced apoptosis, and cell cycle arrest. Xenograft mouse models showed suppressed cell proliferation of tumors in high MET and AXL expression cells. LY2801653 also inhibited the growth of MET and AXL‐independent cells at higher but clinically relevant doses through decreased angiogenesis and M2 macrophages in the tumor microenvironment. In conclusion, our study provides evidence for MET and AXL as prognostic biomarkers and potential therapeutic targets in gastric cancer. The dual MET/AXL inhibitor LY2801653 represents a promising therapeutic strategy for the treatment of patients with gastric carcinoma.

Drug Development in Soft Tissue Sarcomas: Novel Targets and Recent Early Phase Trial Results

Soft tissue sarcomas are a heterogeneous group of rare malignancies with few effective standard therapies. Our understanding of the underlying biology driving tumorigenesis in these mesenchymal tumors have led to a growth in drug development for soft tissue sarcomas. This review focuses on novel targets in soft tissue sarcomas, describes early clinical trial results of drugs directed at these targets, and discusses the data surrounding the use of these compounds in clinical practice and rationale for possible future US Food and Drug Administration approvals.

AXL receptor tyrosine kinase as a promising anti-cancer approach: functions, molecular mechanisms and clinical applications

Molecular targeted therapy for cancer has been a research hotspot for decades. AXL is a member of the TAM family with the high-affinity ligand growth arrest-specific protein 6 (GAS6). The Gas6/AXL signalling pathway is associated with tumour cell growth, metastasis, invasion, epithelial-mesenchymal transition (EMT), angiogenesis, drug resistance, immune regulation and stem cell maintenance. Different therapeutic agents targeting AXL have been developed, typically including small molecule inhibitors, monoclonal antibodies (mAbs), nucleotide aptamers, soluble receptors, and several natural compounds. In this review, we first provide a comprehensive discussion of the structure, function, regulation, and signalling pathways of AXL. Then, we highlight recent strategies for targeting AXL in the treatment of cancer.AXL-targeted drugs, either as single agents or in combination with conventional chemotherapy or other small molecule inhibitors, are likely to improve the survival of many patients. However, future investigations into AXL molecular signalling networks and robust predictive biomarkers are warranted to select patients who could receive clinical benefit and to avoid potential toxicities.

Animal models of well-differentiated/dedifferentiated liposarcoma: utility and limitations

Liposarcoma is a malignant neoplasm of fat tissue. Well-differentiated and dedifferentiated liposarcoma (WDL/DDL) represent the two most clinically observed histotypes occurring in middle-aged to older adults, particularly within the retroperitoneum or extremities. WDL/DDL are thought to represent the broad spectrum of one disease, as they are both associated with the amplification in the chromosomal 12q13-15 region that causes MDM2 and CDK4 overexpression, the most useful predictor for liposarcoma diagnosis. In comparison to WDL, DDL contains additional genetic abnormalities, principally coamplifications of 1p32 and 6q23, that increase recurrence and metastatic rate. In this review, we discuss the xenograft and transgenic animal models generated for studying progression of WDL/DDL, highlighting utilities and pitfalls in such approaches that can facilitate or impede the development of new therapies.

Precision Oncology in Sarcomas: Divide and Conquer

Sarcomas are a heterogeneous group of rare malignancies that exhibit remarkable heterogeneity, with more than 50 subtypes recognized. Advances in next-generation sequencing technology have resulted in the discovery of genetic events in these mesenchymal tumors, which in addition to enhancing understanding of the biology, have opened up avenues for molecularly targeted therapy and immunotherapy. This review focuses on how incorporation of next-generation sequencing has affected drug development in sarcomas and strategies for optimizing precision oncology for these rare cancers. In a significant percentage of soft tissue sarcomas, which represent up to 40% of all sarcomas, specific driver molecular abnormalities have been identified. The challenge to evaluate these mutations across rare cancer subtypes requires the careful characterization of these genetic alterations to further define compelling drivers with therapeutic implications. Novel models of clinical trial design also are needed. This shift would entail sustained efforts by the sarcoma community to move from one-size-fits-all trials, in which all sarcomas are treated similarly, to divide-and-conquer subtype-specific strategies.

Activated tyrosine kinases in gastrointestinal stromal tumor with loss of KIT oncoprotein expression

Oncogenic KIT or PDGFRA receptor tyrosine kinase (TK) mutations are compelling therapeutic targets in gastrointestinal stromal tumors (GISTs), and the KIT/PDGFRA kinase inhibitor, imatinib, is the standard of care for patients with metastatic GIST. However, approximately 10% of KIT-positive GIST metastases lose KIT expression at the time of clinical progression during imatinib therapy. In the present report, we performed TK-activation screens, using phosphotyrosine-TK double immunoaffinity purification and mass spectrometry, in GIST in vitro models lacking KIT expression. These studies demonstrated tyrosine-phosphorylated EGFR, AXL, and EPHA2 in four of six KIT-negative GIST lines (GIST62, GIST522, GIST54, GIST226, GIST48B, and GIST430B), and tyrosine-phosphorylated focal adhesion kinase (FAK) in each of the six KIT-negative lines. AXL expression was strong in KIT-negative or -weak clinical GIST samples that were obtained from progressing metastases during imatinib therapy. AXL knockdown inhibited viability in three KIT-negative GIST cell lines (GIST62, GIST54, and GIST522), but not in an AXL-negative, KIT-positive GIST control cell line (GIST430). AXL inhibition by R428, a specific AXL kinase inhibitor, reduced viability in AXL-activated GIST54. AXL knockdown in GIST62, GIST522, and GIST54 was accompanied by an increase in p21, p27, and p53 expression. By contrast, gefitinib-mediated EGFR inhibition, PF562271-mediated FAK inactivation, and shRNA-mediated knockdowns of EPHA2 and FAK had no effect on viability or colony formation of the KIT-negative GISTs. These findings highlight the potential relevance of AXL/p53 signaling as a therapeutic target in a subset of GISTs that have lost KIT oncoprotein expression.

Eribulin therapy for the treatment of patients with advanced soft tissue sarcoma

Eribulin is a structurally simplified, synthetic macrocyclic ketone analog of halichondrin B, which is a natural, polyether macrolide derived from marine sponges. Eribulin exerts its cytotoxicity by its unique microtubule dynamics inhibitory action. Eribulin was approved in 2010 by the US FDA as a third-line therapy for metastatic breast cancer patients previously treated with an anthracycline and a taxane. In 2016, it was approved for treatment of metastatic liposarcoma for patients who have progressed with anthracycline treatment. In this article, we review the pharmacokinetics, mechanism of action of eribulin with focus on preclinical and clinical data in sarcoma and also the role of miRNAs in soft tissue sarcomas.

Therapeutic Targeting of AXL Receptor Tyrosine Kinase Inhibits Tumor Growth and Intraperitoneal Metastasis in Ovarian Cancer Models

Despite substantial improvements in the treatment strategies, ovarian cancer is still the most lethal gynecological malignancy. Identification of drug treatable therapeutic targets and their safe and effective targeting is critical to improve patient survival in ovarian cancer. AXL receptor tyrosine kinase (RTK) has been proposed to be an important therapeutic target for metastatic and advanced-stage human ovarian cancer. We found that AXL-RTK expression is associated with significantly shorter patient survival based on the The Cancer Genome Atlas patient database. To target AXL-RTK, we developed a chemically modified serum nuclease-stable AXL aptamer (AXL-APTAMER), and we evaluated its in vitro and in vivo antitumor activity using in vitro assays as well as two intraperitoneal animal models. AXL-aptamer treatment inhibited the phosphorylation and the activity of AXL, impaired the migration and invasion ability of ovarian cancer cells, and led to the inhibition of tumor growth and number of intraperitoneal metastatic nodules, which was associated with the inhibition of AXL activity and angiogenesis in tumors. When combined with paclitaxel, in vivo systemic (intravenous [i.v.]) administration of AXL-aptamer treatment markedly enhanced the antitumor efficacy of paclitaxel in mice. Taken together, our data indicate that AXL-aptamers successfully target in vivo AXL-RTK and inhibit its AXL activity and tumor growth and progression, representing a promising strategy for the treatment of ovarian cancer.

The Gas6/TAM System and Multiple Sclerosis

Growth arrest specific 6 (Gas6) is a multimodular circulating protein, the biological actions of which are mediated by the interaction with three transmembrane tyrosine kinase receptors: Tyro3, Axl, and MerTK, collectively named TAM. Over the last few decades, many progresses have been done in the understanding of the biological activities of this highly pleiotropic system, which plays a role in the regulation of immune response, inflammation, coagulation, cell growth, and clearance of apoptotic bodies. Recent findings have further related Gas6 and TAM receptors to neuroinflammation in general and, specifically, to multiple sclerosis (MS). In this paper, we review the biology of the Gas6/TAM system and the current evidence supporting its potential role in the pathogenesis of MS.

Primary liposarcoma of the pancreas: A review illustrated by findings from a recent case

Liposarcoma is the most common soft tissue sarcoma and accounts for 15%-20% of all mesenchymal malignancies. The tumor occurs most frequently in limbs and retroperitoneum, with only rare instances of visceral location reported. Pancreas is a very rare site of primary liposarcoma, with a total of seven cases reported since 1979 and only four of those in the English literature. We review the literature specific for primary liposarcoma of the pancreas and discuss radiological and pathological aspects of this rare tumor type as well as emerging options of treatment. The review is illustrated by findings of a recent case of a dedifferentiated liposarcoma of the pancreas coupled with undifferentiated pleomorphic sarcoma, including the first description of this rare tumor by magnetic resonance imaging. The patient was successfully treated with distal pancreatectomy and splenectomy, followed by adjuvant chemotherapy and radiotherapy. At the 5-year follow-up, the patient showed no signs of recurrence.