Federica Capozzi

The Combination of Sorafenib and Everolimus Abrogates mTORC1 and mTORC2 Upregulation in Osteosarcoma Preclinical Models

Purpose: The multikinase inhibitor sorafenib displays antitumor activity in preclinical models of osteosarcoma. However, in sorafenib-treated patients with metastatic-relapsed osteosarcoma, disease stabilization and tumor shrinkage were short-lived and drug resistance occurred. We explored the sorafenib treatment escape mechanisms to overcome their drawbacks. Experimental Design: Immunoprecipitation, Western blotting, and immunohistochemistry were used to analyze the mTOR pathway [mTOR complex 1 (mTORC1) and mTOR complex 2 (mTORC2)]. Cell viability, colony growth, and cell migration were evaluated in different osteosarcoma cell lines (MNNG-HOS, HOS, KHOS/NP, MG63, U-2OS, SJSA-1, and SAOS-2) after scalar dose treatment with sorafenib (10–0.625 μmol/L), rapamycin-analog everolimus (100–6.25 nmol/L), and combinations of the two. Cell cycle, reactive oxygen species (ROS) production, and apoptosis were assessed by flow cytometry. Nonobese diabetic/severe combined immunodeficient (NOD/SCID) mice injected with MNNG-HOS cells were used to determine antitumor and antimetastatic effects. Angiogenesis and vascularization were evaluated in vitro by exploiting endothelial branching morphogenesis assays and in vivo in xenografted mice and chorioallantoic membranes. Results: After sorafenib treatment, mTORC1 signaling was reduced (downstream target P-S6), whereas mTORC2 was increased (phospho-mTOR Ser2481) in MNNG-HOS xenografts compared with vehicle-treated mice. Combining sorafenib with everolimus resulted in complete abrogation of both mTORC1 [through ROS-mediated AMP-activated kinase (AMPK) activation] and mTORC2 (through complex disassembly). The sorafenib/everolimus combination yielded: (i) enhanced antiproliferative and proapoptotic effects, (ii) impaired tumor growth, (iii) potentiated antiangiogenesis, and (iv) reduced migratory and metastatic potential. Conclusion: mTORC2 activation is an escape mechanism from sorafenib treatment. When sorafenib is combined with everolimus, its antitumor activity is increased by complete inhibition of the mTOR pathway in the preclinical setting. Clin Cancer Res; 19(8); 2117–31. ©2013 AACR.

PARP1 expression drives the synergistic antitumor activity of trabectedin and PARP1 inhibitors in sarcoma preclinical models

BackgroundEnhancing the antitumor activity of the DNA-damaging drugs is an attractive strategy to improve current treatment options. Trabectedin is an isoquinoline alkylating agent with a peculiar mechanism of action. It binds to minor groove of DNA inducing single- and double-strand-breaks. These kinds of damage lead to the activation of PARP1, a first-line enzyme in DNA-damage response pathways. We hypothesized that PARP1 targeting could perpetuate trabectedin-induced DNA damage in tumor cells leading finally to cell death.MethodsWe investigated trabectedin and PARP1 inhibitor synergism in several tumor histotypes both in vitro and in vivo (subcutaneous and orthotopic tumor xenografts in mice). We searched for key determinants of drug synergism by comparative genomic hybridization (aCGH) and gene expression profiling (GEP) and validated their functional role.ResultsTrabectedin activated PARP1 enzyme and the combination with PARP1 inhibitors potentiated DNA damage, cell cycle arrest at G2/M checkpoint and apoptosis, if compared to single agents. Olaparib was the most active PARP1 inhibitor to combine with trabectedin and we confirmed the antitumor and antimetastatic activity of trabectedin/olaparib combination in mice models. However, we observed different degree of trabectedin/olaparib synergism among different cell lines. Namely, in DMR leiomyosarcoma models the combination was significantly more active than single agents, while in SJSA-1 osteosarcoma models no further advantage was obtained if compared to trabectedin alone. aCGH and GEP revealed that key components of DNA-repair pathways were involved in trabectedin/olaparib synergism. In particular, PARP1 expression dictated the degree of the synergism. Indeed, trabectedin/olaparib synergism was increased after PARP1 overexpression and reduced after PARP1 silencing.ConclusionsPARP1 inhibition potentiated trabectedin activity in a PARP1-dependent manner and PARP1 expression in tumor cells might be a useful predictive biomarker that deserves clinical evaluation.

The combination of sorafenib and everolimus shows antitumor activity in preclinical models of malignant pleural mesothelioma

BackgroundMalignant Pleural Mesothelioma (MPM) is an aggressive tumor arising from mesothelial cells lining the pleural cavities characterized by resistance to standard therapies. Most of the molecular steps responsible for pleural transformation remain unclear; however, several growth factor signaling cascades are known to be altered during MPM onset and progression. Transducers of these pathways, such as PIK3CA-mTOR-AKT, MAPK, and ezrin/radixin/moesin (ERM) could therefore be exploited as possible targets for pharmacological intervention. This study aimed to identify ‘druggable’ pathways in MPM and to formulate a targeted approach based on the use of commercially available molecules, such as the multikinase inhibitor sorafenib and the mTOR inhibitor everolimus.MethodsWe planned a triple approach based on: i) analysis of immunophenotypes and mutational profiles in a cohort of thoracoscopic MPM samples, ii) in vitro pharmacological assays, ii) in vivo therapeutic approaches on MPM xenografts. No mutations were found in ‘hot spot’ regions of the mTOR upstream genes (e.g. EGFR, KRAS and PIK3CA).ResultsPhosphorylated mTOR and ERM were specifically overexpressed in the analyzed MPM samples. Sorafenib and everolimus combination was effective in mTOR and ERM blockade; exerted synergistic effects on the inhibition of MPM cell proliferation; triggered ROS production and consequent AMPK-p38 mediated-apoptosis. The antitumor activity was displayed when orally administered to MPM-bearing NOD/SCID mice.ConclusionsERM and mTOR pathways are activated in MPM and ‘druggable’ by a combination of sorafenib and everolimus. Combination therapy is a promising therapeutic strategy against MPM.

Cytokine Induced Killer cells are effective against sarcoma cancer stem cells spared by chemotherapy and target therapy.

ABSTRACT Metastatic bone and soft tissue sarcomas often relapse after chemotherapy (CHT) and molecular targeted therapy (mTT), maintaining a severe prognosis. A subset of sarcoma cancer stem cells (sCSC) is hypothesized to resist conventional drugs and sustain disease relapses. We investigated the immunotherapy activity of cytokine induced killer cells (CIK) against autologous sCSC that survived CHT and mTT. The experimental platform included two aggressive bone and soft tissue sarcoma models: osteosarcoma (OS) and undifferentiated-pleomorphic sarcoma (UPS). To visualize putative sCSC we engineered patient-derived sarcoma cultures (2 OS and 3 UPS) with a lentiviral sCSC-detector wherein the promoter of stem-gene Oct4 controls the expression of eGFP. We visualized a fraction of sCSC (mean 24.2 ± 5.2%) and confirmed their tumorigenicity in vivo. sCSC resulted relatively resistant to both CHT and mTT in vitro. Therapeutic doses of doxorubicin significantly enriched viable eGFP+sCSC in both OS (2.6 fold, n = 16) and UPS (2.3 fold, n = 29) compared to untreated controls. Treatment with sorafenib (for OS) and pazopanib (for UPS) also determined enrichment (1.3 fold) of viable eGFP+sCSC, even if less intense than what observed after CHT. Sarcoma cells surviving CHT and mTT were efficiently killed in vitro by autologous CIK even at minimal effector/target ratios (40:1 = 82%, 1:4 = 29%, n = 13). CIK immunotherapy did not spare sCSC that were killed as efficiently as whole sarcoma cell population. The relative chemo-resistance of sCSC and sensitivity to CIK immunotherapy was confirmed in vivo. Our findings support CIK as an innovative, clinically explorable, approach to eradicate chemo-resistant sCSC implicated in tumor relapse.

Abstract 3709: PARP1 expression (PARP1expr) drives synergy between PARP1 inhibitors (PARP1-Is) and trabectedin (TR)

Purpose of study. An attractive strategy to improve antitumor treatments is to inflict cytotoxic DNA damage with chemotherapy, and then impede DNA repair by molecular targeting. TR is a new drug characterized by a peculiar mechanism of action: TR traps DNA repair machinery leading to DNA damage, particularly in BRCA1/2-deficient tumors. We speculated that TR might activate PARP1, a key player in DNA-repair, and that subsequent PARP1 inhibition perpetuates TR-induced DNA damage leading to cell death. Experimental procedures and results. We developed a preclinical platform of 31 cell lines from different histotypes to explore the potential synergy between TR and the PARP1-Is olaparib (OL) and veliparib. We demonstrated that, regardless of BRCA1/2 status, PARP1-Is significantly increased TR activity, but a 15-fold range of sensitivity to the combination was observed. OL was proven the best PARP-I to combine with TR, probably due to its PARP1 trapping activity. In selected experiments, whole-genome expression profiling and GSEA analysis comparing cells displaying high vs. low synergism of the combination (HS-C vs. LS-C) revealed that DDR, G2/M cell cycle checkpoint, and DNA repair pathways were mechanistically involved in TR+OL synergy. TR induced PARP1 activation in 3/6 cell lines and PARP1-Is completely blocked both basal and TR-induced PARP1 activation. OL enhanced DNA damage response in 6/6 cell lines, but unrepairable DNA fragmentation was obtained in cells with high PARP1expr only. In two independent cell panels TR+OL synergism was directly related to PARP1expr both at mRNA (Pearson score r: 0.70, p = 0.00079) and protein level (r: 0.71, p = 0.015). Silencing and overexpression experiments validated the functional role of PARP1expr in determining TR+OL synergism: in HS-C the downmodulation of PARP1expr reduced sensitivity to TR+OL while the overexpression of PARP1 in LS-C rose TR+OL activity to levels observed in HS-C. Subcutaneous, intravenous and orthotopic xenografts of one HS-C (DMR) and one LS-C (SJSA-1) in NOD/SCID mice revealed OL significantly increased antitumor and antimetastatic activity of TR in cells with high PARP1expr only. Finally, we demonstrated that basal PARP1expr PARP1 activation by other cytotoxics with a stronger PARP1 activation observed in cells with high vs. low PARP1expr, regardless of the considered drug. Conclusions. OL enhances and potentially broaden TR cytotoxicity. TR+OL combination is particularly attractive in tumors harboring high PARP1expr and specific DDR-R gene signatures that might become predictive biomarkers of response. Future clinical validation of TR+OL combination may extend the use of PARP1-Is beyond BRCA1/2 defective tumors. Indeed, the crucial role of PARP1expr is confirmed regardless of tumor histotype and BRCA1/2 status. Further studies of combination between PARP1-Is and other cytotoxics should consider basal PARP1expr and activation after drug exposure. Citation Format: Ymera Pignochino, Federica Capozzi, Lorenzo D’ambrosio, Carmine Dell’aglio, Marco Basirico, Paola Boccone, Erica Palesandro, Loretta Gammaitoni, Dario Sangiolo, Maria Serena Benassi, Massimo Aglietta, Giovanni Grignani. PARP1 expression (PARP1expr) drives synergy between PARP1 inhibitors (PARP1-Is) and trabectedin (TR). [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3709.

Abstract LB-366: Everolimus (EV) potentiates Sorafenib (SOR)activity in osteosarcoma (OS) preclinical models: a combination targeting the crosstalk between ERK1/2 and mTORC1/2 signaling pathways

Proceedings: AACR 103rd Annual Meeting 2012‐‐ Mar 31‐Apr 4, 2012; Chicago, IL OS is the most frequent primary bone tumor in children and young adults.The mammalian Target of Rapamycin (mTOR) and the Extracellular Regulated Kinases (ERK)1/2 pathways have been shown to cooperate in survival advantage of OS. Inhibition of this signaling can be a rational pharmacological strategy to impinge on OS progression. This study pursued the dual blockage of ERK1/2 and mTOR pathways by combining the multikinase inhibitor SOR with the rapamycin analog EV. The synergistic anti-profilerative effect was found against 5 out 7 OS cell lines (combination index<1, based on Chou-Talalay method). The inhibition of OS colony growth, due to cell cycle arrest and apoptosis induction was obtained. Mechanistically SOR alone, but EV, inhibited phospho-ERK1/2. EV and SOR as single agent induced the down-regulation of P-S6, P-4EBP. EV alone induced an increase in phospho-AKT as a consequence of the release of negative feed back by MTORC1 on MTORC2. Nonetheless, the combined treatment completely abrogated both ERK1/2 and MTORC1/2. The crosstalk among these pathways was interrupted by AMPK activation due to sorafenib-induced ROS burst and MTORC2 disassembling. The anti-tumoral activity and the inhibition of angiogenesis and metastasis in vivo were demonstrated against OS xenografts in NOD/SCID mice and in chicken chorioallantoic membrane model. A 28 daily oral gavage of mice (6/group) with SOR 5mg/kg, EV 1mg/kg, or their combination reduced tumor growth to 34%, 46%, and 29% of control slowing down cell proliferation and inducing apoptosis. In vivo model of OS metastasis obtained by e.v injection of OS cells confirmed the high metastatic potential of human OS consistently with the clinical experience. However, daily treatment of mice induced a significant reduction in number and size of lung metastases (foci area 65%, 74% and 29% of control obtained after 14 daily SOR, EV, and combined treatment). Anti-migratory effect was evidenced in 7 OS cell lines and was attributable to SRC/FAK/ERM pathway inhibition. HUVEC branching morphogenesis inhibition and reduction of blood vessel density in xenografts confirmed a strong potentiation of anti-angiogenic activity of drug combination. These results straighten our understanding of the networking nature of oncogenic signal transduction circuits in OS, therefore sustaining the rational for testing combination of sorafenib and everolimus in clinical setting. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr LB-366. doi:1538-7445.AM2012-LB-366