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.

Clinical Observations and Molecular Variables of Primary Vascular Leiomyosarcoma.

IMPORTANCE: Vascular leiomyosarcomas are a rare subtype of leiomyosarcomas that most commonly affect the inferior vena cava and account for 5% of all leiomyosarcomas. These tumors are aggressive malignant tumors for which adjuvant modalities have not shown increased efficacy compared with surgery. OBJECTIVES: To evaluate the outcomes of patients with vascular leiomyosarcoma and the association between vascular leiomyosarcomas and immunohistochemical molecular markers, to determine their potential prognostic and therapeutic utility. DESIGN, SETTING, AND PARTICIPANTS: Retrospective medical record review of a cohort of 77 patients who presented to the University of Texas MD Anderson Cancer Center in Houston during the period from January 1993 to April 2012. Data were analyzed during the period from November 2012 to May 2015. All of the patients received a confirmed diagnosis of vascular leiomyosarcoma. Immunohistochemical studies for biomarkers were performed on a tissue microarray that included 26 primary specimens of vascular leiomyosarcoma. MAIN OUTCOMES AND MEASURES: Demographic and clinical factors were evaluated to assess clinical course, patterns of recurrence, and survival outcomes for patients with primary vascular leiomyosarcoma. A univariate Cox proportional hazards model was used to correlate disease-specific survival and time to recurrence with potential prognostic indicators. RESULTS: Sixty-three patients with localized disease who underwent surgical resection formed the study population, and their data were used for subsequent outcomes analysis. The median age at diagnosis was 58 years (range, 22-78 years). The majority of patients were female (41 patients [65%]) and white (51 patients [81%]). The 5-year disease-specific survival rate after tumor resection was 65%. The median time to local recurrence was 43 months, the median time to distant recurrence was 25 months, and the median time to concurrent local and distant recurrences was 15 months (P = .04). Strong expressions of cytoplasmic ß-catenin (hazard ratio, 5.33 [95% CI, 0.97-29.30]; P = .06) and insulinlike growth factor 1 receptor (hazard ratio, 2.74 [95% CI, 1.14-6.56]; P = .02) were associated with inferior disease-specific survival. CONCLUSIONS AND RELEVANCE: Vascular leiomyosarcomas are aggressive malignant tumors, with high recurrence rates. Expressions of ß-catenin and insulinlike growth factor 1 receptor were associated with poor disease-specific survival. Prospective studies should evaluate the clinical and therapeutic utility of these molecular markers.

Progressive loss of myogenic differentiation in leiomyosarcoma has prognostic value.

AIMS: Well-differentiated leiomyosarcomas show morphologically recognizable smooth muscle differentiation, whereas poorly differentiated tumours may form a spectrum with a subset of undifferentiated pleomorphic sarcomas. The expression of certain muscle markers has been reported to have prognostic impact. We investigated the correlation between the morphological spectrum and the muscle marker expression profile of leiomyosarcoma, and the impact of these factors on patient outcomes. METHODS AND RESULTS: Tissue microarrays including 202 non-uterine and 181 uterine leiomyosarcomas with a spectrum of tumour morphologies were evaluated for expression of immunohistochemical markers of muscle differentiation. Poorly differentiated tumours frequently lost one or more conventional smooth muscle markers [smooth muscle actin, desmin, h-caldesmon, and smooth muscle myosin (P < 0.0001)], as well as the more recently described markers SLMAP, MYLK, and ACTG2 (P < 0.0001). In primary tumours, both desmin and CFL2 expression predicted improved overall survival in multivariate analyses (P = 0.0111 and P = 0.043, respectively). Patients with muscle marker-enriched tumours (expressing all four conventional markers or any three of ACTG2, CFL2, CASQ2, MYLK, and SLMAP) had improved overall survival (P < 0.05) in univariate analyses. CONCLUSIONS: Morphologically and immunohistochemically, poorly differentiated leiomyosarcomas can masquerade as undifferentiated pleomorphic sarcomas with progressive loss of muscle markers. The expression of muscle markers has prognostic significance in primary leiomyosarcomas independently of tumour morphology.

Localized and metastatic myxoid/round cell liposarcoma: clinical and molecular observations.

BACKGROUND: Myxoid liposarcoma (MLPS), a disease especially of young adults with potential for local recurrence and metastasis, currently lacks solid prognostic factors and therapeutic targets. The authors of this report evaluated the natural history and outcome of patients with MLPS and commonly deregulated protein biomarkers. METHODS: Medical records were retrospectively reviewed for patients who presented to the authors' institution with localized (n = 207) or metastatic (n = 61) MLPS (1990 to 2010). A tissue microarray of MLPS patient specimens (n = 169) was constructed for immunohistochemical analysis of molecular markers. RESULTS: The 5-year and 10-year disease-specific survival rates among patients with localized disease were 93% and 87%, respectively; male gender, age >45 years, and recurrent tumor predicted poor outcome. The local recurrence rate was 7.4%, and the risk of local recurrence was associated with recurrent tumors and nonextremity disease location. Male gender was the main risk factor for metastatic disease, which occurred in 13% of patients. Forty percent of patients who had localized disease received chemotherapy, mostly in the neoadjuvant setting. Immunohistochemical analysis revealed significantly higher expression of C-X-C chemokine receptor type 4 (CXCR4) and platelet-derived growth factor beta (PDGFR-ß) in metastatic lesions versus localized lesions. Tumors with a round cell phenotype expressed increased levels of CXCR4, p53, adipophilin, PDGFR-α, PDGFR-ß, and vascular endothelial growth factor relative to myxoid phenotype. Only the receptor tyrosine kinase encoded by the AXL gene (AXL) was identified as a prognosticator of disease-specific survival in univariate analysis. CONCLUSIONS: In this study, the authors identified clinical and molecular outcome prognosticators for patients with MLPS as well as several potential therapeutic targets.

Uterine leiomyosarcoma management, outcome, and associated molecular biomarkers: a single institution's experience.

BACKGROUND: Uterine leiomyosarcoma (ULMS) is an aggressive, rapidly progressive tumor lacking clinical and molecular predictors of outcome. METHODS: ULMS patients (n = 349) were classified by disease status at presentation to MDACC as having intra-abdominal (n = 157) or distant metastatic disease (n = 192). Patient, tumor, treatment, and outcome variables were retrospectively retrieved. Formalin-fixed, paraffin-embedded tumor and control tissues from these patients (n = 109) were assembled in a tissue microarray and evaluated for hormone receptors and markers of angiogenesis, cell-cycle progression and survival. Patient, tumor, and treatment variables were correlatively analyzed. RESULTS: The 5- and 10-year disease-specific survival (DSS) for the cohort was 42 and 27 %, respectively. Patients with primary intra-abdominal tumors had better outcomes than those with recurrent intraperitoneal tumors. Whites had a more favorable prognosis. In patients with intra-abdominal tumors, only mitotic count >10M/10HPF portended poorer prognosis. Patients with pulmonary metastasis had improved outcomes with "curative" metastasectomy. ULMS samples exhibited loss of ER and PR expression, overexpressed Ki-67, and altered p53, Rb, p16, cytoplasmic ß-catenin, EGFR, PDGFR-α, PDGFR-ß, and AXL levels. Metastatic tumors had increased VEGF, Ki-67, and survivin expression versus localized disease. Survivin and ß-catenin expression were associated with intraperitoneal recurrence; high bcl-2 expression predicted longer DSS. CONCLUSIONS: Analysis of both clinicopathologic factors and immunohistochemical biomarkers in ULMS identified several prognostic clinical and molecular factors, suggesting that further study may lead to improved ULMS understanding and treatment.

Targeting the PI3K/mTOR axis, alone and in combination with autophagy blockade, for the treatment of malignant peripheral nerve sheath tumors.

There is a critical need for efficacious therapeutic strategies to improve the outcome of patients afflicted by malignant peripheral nerve sheath tumors (MPNST). Multiple lines of evidence suggest a role for deregulated phosphoinositide 3-kinase (PI3K)/mTOR signaling in MPNST, making this axis an attractive target for therapeutic manipulation. On the basis of previous observations obtained from in vitro experimentation, here we aimed to assess the effects of PI3K/mTOR blockade on MPNST growth in vivo. The anti-MPNST impact of XL765, a dual PI3K/mTOR inhibitor currently being evaluated in human cancer clinical trials, was tested in two human MPNST xenograft models (STS26T and MPNST724) and an experimental model of pulmonary metastasis (STS26T). XL765 abrogated human MPNST local and metastatic growth in severe combined immunodeficient mice. Notably, this therapeutic approach failed to induce apoptosis in MPNST cells but rather resulted in marked productive autophagy. Importantly, genetic and pharmacologic autophagy blockade reversed apoptotic resistance and resulted in significant PI3K/mTOR inhibition-induced MPNST cell death. The addition of the autophagy inhibitor, chloroquine, to the therapeutic regimen of MPNST xenografts after pretreatment with XL765 resulted in superior antitumor effects as compared with either agent alone. Together, preclinical studies described here expand our previous findings and suggest that PI3K/mTOR inhibition alone and (most importantly) in combination with autophagy blockade may comprise a novel and efficacious therapy for patients harboring MPNST.

Dual targeting of mTOR and aurora-A kinase for the treatment of uterine Leiomyosarcoma.

PURPOSE: The significance of mTOR activation in uterine leiomyosarcoma (ULMS) and its potential as a therapeutic target were investigated. Furthermore, given that effective therapies likely require combination mTOR blockade with inhibition of other targets, coupled with recent observations suggesting that Aurora-A kinase (Aurk-A) deregulations commonly occur in ULMS, the preclinical impact of dually targeting both pathways was evaluated. EXPERIMENTAL DESIGN: Immunohistochemical staining was used to evaluate expression of activated mTOR components in a large (>200 samples) ULMS tissue microarray. Effects of mTOR blockade (using rapamycin) and Aurk-A inhibition (using MLN8237) alone and in combination on human ULMS cell growth, cell-cycle progression, and apoptosis were assessed in cellular assays. Drug interactions were determined via combination index analyses. The antitumor effects of inhibitors alone or in combination were evaluated in vivo. RESULTS: Enhanced mTOR activation was seen in human ULMS samples. Increased pS6RP and p4EBP1 expression correlated with disease progression; p4EBP1 was found to be an independent prognosticator of patient outcome. Rapamycin inhibited growth and cell-cycle progression of ULMS cell strains/lines in culture. However, only a cytostatic effect on tumor growth was found in vivo. Combining rapamycin with MLN8237 profoundly (and synergistically) abrogated ULMS cells' growth in culture; interestingly, these effects were seen only when MLN8237 was preadministered. This novel therapeutic combination and scheduling regimen resulted in marked tumor growth inhibition in vivo. CONCLUSIONS: mTOR and Aurk-A pathways are commonly deregulated in ULMS. Preclinical data support further exploration of dual mTOR and Aurk-A therapeutic blockade for human ULMS.

Survivin is a viable target for the treatment of malignant peripheral nerve sheath tumors.

PURPOSE: To examine the role of survivin as a therapeutic target in preclinical models of human malignant peripheral nerve sheath tumors (MPNST) EXPERIMENTAL DESIGN: Survivin protein expression levels and subcellular localization were examined immunohistochemically in an MPNST tissue microarray. Human MPNST cells were studied in vitro and in vivo; real-time PCR, Western blotting, and immunocytochemical analyses were used to evaluate survivin expression and localization activation. Cell culture assays were used to evaluate the impact of anti-survivin-specific siRNA inhibition on cell growth and cell-cycle progression and survival. The effect of the small-molecule survivin inhibitor YM155 on local and metastatic MPNST growth was examined in vivo. RESULTS: Survivin was found to be highly expressed in human MPNSTs; enhanced cytoplasmic subcellular localization differentiated MPNSTs from their plexiform neurofibroma premalignant counterparts. Human MPNST cell lines exhibited survivin mRNA and protein overexpression; expression in both nuclear and cytoplasmic compartments was noted. Survivin knockdown abrogated MPNST cell growth, inducing G(2) cell-cycle arrest and marked apoptosis. YM155 inhibited human MPNST xenograft growth and metastasis in severe combined immunodeficient (SCID) mice. Antitumor effects were more pronounced in fast-growing xenografts. CONCLUSIONS: Our studies show an important role for survivin in human MPNST biology. Patients with MPNSTs should be considered for ongoing or future clinical trials that evaluate anti-survivin therapeutic strategies. Most importantly, future investigations should evaluate additional pathways that can be targeted in combination with survivin for maximal synergistic anti-MPNST effects.

FAP-related desmoid tumors: a series of 44 patients evaluated in a cancer referral center.

Desmoid tumors (DTs), the commonest extra-intestinal manifestation of familial adenomatosis polyposis (FAP), are monoclonal neoplasms demonstrating fibroblastic - myofibroblastic differentiation; they are locally invasive without metastatic capacity. FAP-associated DT natural history knowledge is limited; we examined patient and tumor characteristics for a FAP-DT cohort and evaluated anti-DT therapy molecular target expression levels (immunohistochemical analyses, FAP-DT tissue microarray; TMA). Forty-four patients were classified as intra-abdominal (IA; n=26), abdominal wall (AW)/extra-abdominal (EA; n=12) or concomitant IA/AW (n=6) based on DT primary diagnosis location. Positive family histories were found in 62% of FAP versus 10% of DT patients. Surgery was the mainstay therapy for AW/EW patients, whereas IA DTs received surgery, chemotherapy, radiotherapy, tamoxifen, NSAIDs, and/or imatinib. Eight of 20 completely resected DTs in the IA and AW/EA groups recurred; 12 of 38 patients in these groups (33%) developed secondary lesions elsewhere. Two intestinal mesenteric DT patients died of disease, three from other cancers, 27 are alive with disease and 12 are alive without disease. All evaluable FAP-DT exhibited nuclear ß-catenin, 65% were positive for cyclin D1, and 66% expressed nuclear p53. No ERα expression was observed, but ERß was expressed in 72%. COX2 was expressed in all evaluable FAP-DTs. KIT was rarely found in DTs but both PDGFRs and their ligands were expressed. Comparing biomarker expression (IA vs. EA DTs), only nuclear ER-ß staining was significantly higher in EA lesions (p=0.0070); no other markers were site informative. Enhanced knowledge of FAP-DT molecular underpinnings will facilitate development of novel therapeutic strategies.

Increased midkine expression correlates with desmoid tumour recurrence: a potential biomarker and therapeutic target.

Desmoid tumours (DTs) are soft tissue monoclonal neoplasms exhibiting a unique phenotype, consisting of aggressive local invasiveness without metastatic capacity. While DTs can infrequently occur as part of familial adenomatosis polyposis, most cases arise sporadically. Sporadic DTs harbour a high prevalence of CTNNB1 mutations and hence increased ß-catenin signalling. However, ß-catenin downstream transcriptional targets and other molecular deregulations operative in DT inception and progression are currently not well defined, contributing to the lack of sensitive molecular prognosticators and efficacious targeted therapeutic strategies. We compared the gene expression profiles of 14 sporadic DTs to those of five corresponding normal tissues and six solitary fibrous tumour specimens. A DT expression signature consisting of 636 up- and 119 down-regulated genes highly enriched for extracellular matrix, cell adhesion and wound healing-related proteins was generated. Furthermore, 98 (15%) of the over-expressed genes were demonstrated to contain a TCF/LEF consensus binding site in their promoters, possibly heralding direct ß-catenin downstream targets relevant to DT. The protein products of three of the up-regulated DT genes: ADAM12, MMP2 and midkine, were found to be commonly expressed in a large cohort of human DT samples assembled on a tissue microarray. Interestingly, enhanced midkine expression significantly correlated with a higher propensity and decreased time for primary DT recurrence (log-rank p = 0.0025). Finally, midkine was found to enhance the migration and invasion of primary DT cell cultures. Taken together, these studies provide insights into potential DT molecular aberrations and novel ß-catenin transcriptional targets. Further studies to confirm the utility of midkine as a clinical DT molecular prognosticator and a potential therapeutic target are therefore warranted. Raw gene array data can be found at: http://smd.stanford.edu/

Incidence and risk factors of venous thromboembolism in colorectal surgery: does laparoscopy impart an advantage?

OBJECTIVES: Laparoscopy is increasingly used in colon and rectal procedures. However, little is known regarding the incidence of venous thromboembolism (VTE) in laparoscopic colorectal (LC) compared with that in open colorectal (OC) procedures. We aimed to compare the incidences and to highlight the risk factors of developing VTE after LC and OC surgery. DESIGN: Analysis of the Nationwide Inpatient Sample data from 2002 through 2006. SETTING: National database. PATIENTS: Patients who underwent elective LC and OC surgery from 2002 through 2006. MAIN OUTCOMES MEASURE: Incidence of VTE during initial hospitalization after LC and OC surgery; VTE classified by surgical site, pathology type, and at-risk patient population. RESULTS: Over a 60-month period, 149,304 patients underwent LC or OC resection. Overall, the incidence of VTE was significantly higher in OC cases (2036 of 141,456 [1.44%]) compared with the incidence in LC cases (65 of 7848 [0.83%]) (P < .001). When stratified according to pathologic condition and surgical site, the overall rate of VTE was highest in patients with inflammatory bowel disease and in those undergoing rectal resections. Patients who underwent OC surgery were almost twice as likely to develop VTE compared with patients who underwent LC surgery. We also identified malignancy, obesity, and congestive heart failure as statistically significant (P < .05) risk factors for VTE in OC and LC surgery. CONCLUSIONS: On the basis of data from a large clinical data set, the incidence of perioperative VTE is lower after LC than after OC surgery. These findings may help colorectal surgeons use appropriate VTE prophylaxis for patients undergoing colorectal procedures.