sirolimus and Sarcoma--Ewing

Despite the use of recommended chemotherapy regimens, patients with metastatic sarcomas have a poor prognosis. To date, the median overall survival for metastatic disease remains less than 18 months. First-line treatment of most metastatic sarcomas consists of chemotherapy with or without surgical excision of residual disease, followed by "watchful waiting" until disease progression or recurrence. According to the current treatment paradigm, recommended by United States and European clinical guidelines, chemotherapy is administered for a fixed number of cycles, and then a watchful waiting approach is taken once a best response is achieved. Single-agent doxorubicin remains the standard for treatment of most soft-tissue sarcomas (STS), as combination and dose-intense regimens have largely failed to improve survival. Combination chemotherapy is the standard treatment approach for osteosarcoma and Ewing's sarcoma, but outcomes are poor for patients with recurrent disease. In order to improve outcomes (in particular, progression-free survival [PFS] and overall survival [OS]), strategies shown to be effective in other solid malignancies, such as maintenance therapy and long-term treatment with targeted therapy, are being investigated in patients with advanced sarcomas. One potential promising approach is the use of mammalian target of rapamycin (mTOR) inhibitors for maintenance therapy. One such mTOR inhibitor, ridaforolimus (AP23573, MK-8669), is currently being evaluated in patients with advanced bone and STS in the ongoing Sarcoma mUlti-Center Clinical Evaluation of the Efficacy of riDaforolimus (SUCCEED) trial.

Topics: Antineoplastic Combined Chemotherapy Protocols; Bone Neoplasms; Carcinoma, Non-Small-Cell Lung; Disease-Free Survival; Doxorubicin; Female; Humans; Lung Neoplasms; Osteosarcoma; Ovarian Neoplasms; Sarcoma; Sarcoma, Ewing; Sirolimus; Soft Tissue Neoplasms; TOR Serine-Threonine Kinases

Temsirolimus was combined with cixutumumab, a fully human IgG1 monoclonal antibody directed at the insulin growth factor-1 receptor (IGF-1R).. Patients received cixutumumab, 6 mg/kg i.v. weekly, and temsirolimus, 25 to 37.5 mg i.v. weekly (4-week cycles), with restaging after 8 weeks. Median follow-up was 8.9 months.. Twenty patients [17 with Ewing's sarcoma (EWS), 3 with desmoplastic small-round cell tumor (DSRCT)] were enrolled. Twelve patients (60%) were men with a median age of 24 years and six median prior systemic therapies in a metastatic setting. The most frequent toxicities were thrombocytopenia (85%), mucositis (80%), hypercholesterolemia (75%), hypertriglyceridemia (70%), and hyperglycemia (65%; mostly grade I-II). Seven of 20 patients (35%) achieved stable disease (SD) for more than 5 months or complete/partial (CR/PR) responses. Tumor regression of more than 20% (23%, 23%, 27%, 100%, 100%) occurred in five of 17 (29%) patients with EWS, and they remained on study for 8 to 27 months. One of six patients with EWS who previously developed resistance to a different IGF-1R inhibitor antibody achieved a CR. Four of the seven best responders developed grade III mucositis, myelosuppression, or hyperglycemia, which were controlled while maintaining drug dose.. Cixutumumab combined with temsirolimus was well-tolerated and showed preliminary evidence of durable antitumor activity in heavily pretreated EWS family tumors.

Topics: Adolescent; Adult; Antibodies, Monoclonal; Antibodies, Monoclonal, Humanized; Antineoplastic Combined Chemotherapy Protocols; Bone Neoplasms; Cohort Studies; Desmoplastic Small Round Cell Tumor; Female; Humans; Male; Neoplasm Grading; Prognosis; Receptor, IGF Type 1; Remission Induction; Sarcoma, Ewing; Sirolimus; TOR Serine-Threonine Kinases; Young Adult

Therapies cotargeting insulin-like growth factor receptor 1 (IGF-1R) and mammalian target of rapamycin (mTOR) have demonstrated remarkable, albeit short-lived, clinical responses in a subset of Ewing sarcoma (ES) patients. However, the mechanisms of resistance and applicable strategies for overcoming drug resistance to the IGF-1R/mTOR blockade are still undefined.. To elucidate predominant mechanism(s) of acquired drug resistance while identifying synergistic drug combinations that improve clinical efficacy, we generated more than 18 ES cell lines resistant to IGF-1R- or mTOR-targeted therapy. Two small-molecule inhibitors of IGF-1R were chosen, NVP-ADW-742 (IGF-1R-selective) and OSI-906 (a dual IGF-1R/insulin receptor alpha [IR-α] inhibitor). Reverse-phase protein lysate arrays (RPPAs) revealed proteomic changes linked to IGF-1R/mTOR resistance, and selected proteins were validated in cell-based assays, xenografts, and within human clinical samples. All statistical tests were two-sided.. Novel mechanisms of resistance (MOR) emerged after dalotuzumab-, NVP-ADW-742-, and OSI-906-based targeting of IGF-1R. MOR to dalotuzumab included upregulation of IRS1, PI3K, and STAT3, as well as p38 MAPK, which was also induced by OSI-906. pEIF4E(Ser209), a key regulator of Cap-dependent translation, was induced in ridaforolimus-resistant ES cell lines. Unique drug combinations targeting IGF-1R and PI3K-alpha or Mnk and mTOR were synergistic in vivo and vitro (P < .001) as assessed respectively by Mantel-Cox and isobologram testing.. We discovered new druggable targets expressed by chemoresistant ES cells, xenografts, and relapsed human tumors. Joint suppression of these newfound targets, in concert with IGF-1R or mTOR blockade, should improve clinical outcomes.

Topics: Adenosine Triphosphatases; Animals; Antibodies, Monoclonal; Antibodies, Monoclonal, Humanized; Antineoplastic Combined Chemotherapy Protocols; Bone Neoplasms; Cation Transport Proteins; Cell Line, Tumor; Copper-Transporting ATPases; Drug Resistance, Neoplasm; Drug Synergism; Humans; Imidazoles; Insulin Receptor Substrate Proteins; Male; Mice; Mice, SCID; Neoplasm Transplantation; Nucleocytoplasmic Transport Proteins; p38 Mitogen-Activated Protein Kinases; Phosphatidylinositol 3-Kinase; Phosphoinositide-3 Kinase Inhibitors; Protein Array Analysis; Pyrazines; Pyrimidines; Pyrroles; Receptor, IGF Type 1; Receptors, Somatomedin; Sarcoma, Ewing; Sirolimus; STAT3 Transcription Factor; TOR Serine-Threonine Kinases; Up-Regulation

Recent evidence implicates the insulin-like growth factor (IGF) pathway in development of Ewing sarcoma, a highly malignant bone and soft-tissue tumor that primarily affects children and young adults. Despite promising results from preclinical studies of therapies that target this pathway, early-phase clinical trials have shown that a significant fraction of patients do not benefit, suggesting that cellular factors determine tumor sensitivity. Using FAIRE-seq, a chromosomal deletion of the PTEN locus in a Ewing sarcoma cell line was identified. In primary tumors, PTEN deficiency was observed in a large subset of cases, although not mediated by large chromosomal deletions. PTEN loss resulted in hyperactivation of the AKT signaling pathway. PTEN rescue led to decreased proliferation, inhibition of colony formation, and increased apoptosis. Strikingly, PTEN loss decreased sensitivity to IGF1R inhibitors but increased responsiveness to temsirolimus, a potent mTOR inhibitor, as marked by induction of autophagy. These results suggest that PTEN is lost in a significant fraction of primary tumors, and this deficiency may have therapeutic consequences by concurrently attenuating responsiveness to IGF1R inhibition while increasing activity of mTOR inhibitors. The identification of PTEN status in the tumors of patients with recurrent disease could help guide the selection of therapies.. PTEN status in Ewing sarcoma affects cellular responses to IGFI and mTOR-directed therapy, thus justifying its consideration as a biomarker in future clinical trials.

Topics: Autophagy; Cell Line, Tumor; Gene Deletion; Human Umbilical Vein Endothelial Cells; Humans; Insulin-Like Growth Factor I; Proto-Oncogene Proteins c-akt; PTEN Phosphohydrolase; Receptor, IGF Type 1; Sarcoma, Ewing; Signal Transduction; Sirolimus; TOR Serine-Threonine Kinases

Mammalian target of rapamycin suppression by rapamycin inhibits tumor growth and neovascularization via cyclooxygenase-2 (COX-2) downregulation with no effect on lung metastases. We hypothesize that combining a selective COX-2 antagonist (celecoxib) with rapamycin would decrease lung metastases.. Ewing sarcoma cells (SK-NEP-1) were surgically implanted into the left kidney of athymic mice (n = 40). The mice were divided into 4 treatment groups (control, rapamycin only, celecoxib only, and combination) and then killed at 6 weeks. Primary tumors were weighed. Vasculature was examined using lectin angiography and immunohistochemistry, and lung metastases were examined using H&E and CD99 immunostaining. Tumor weight and lung metastases were analyzed.. Mean primary tumor weights were significantly reduced in the rapamycin-treated groups but not in the celecoxib-only group. Lectin angiography and endothelial markers immunostaining showed markedly decreased vascularity in the rapamycin-treated groups but not in the celecoxib-only group. Celecoxib-treated groups showed significantly fewer mice with lung metastases than non-celecoxib-treated groups.. Celecoxib prevents lung metastasis in a murine model of Ewing sarcoma with no effect on tumor size or neovascularization. Cyclooxygenase-2 may represent a future potential target for metastatic disease prevention.

Topics: Angiogenesis Inhibitors; Animals; Celecoxib; Cell Line, Tumor; Cyclooxygenase 2; Cyclooxygenase 2 Inhibitors; Disease Models, Animal; Down-Regulation; Drug Therapy, Combination; Female; Lung Neoplasms; Mice; Mice, Nude; Neoplasm Metastasis; Neovascularization, Pathologic; Pyrazoles; Sarcoma, Ewing; Sirolimus; Sulfonamides

Ewing's and osteogenic sarcoma are two of the leading causes of cancer deaths in children and adolescents. Recent data suggest that sarcomas may depend on the insulin-like growth factor type 1 (IGF-1) receptor (IGF1R) and/or the insulin receptor (INSR) to drive tumor growth, survival, and resistance to mammalian target of rapamycin complex 1 (mTORC1) inhibitors. We evaluated the therapeutic value of ganitumab (AMG 479; C(6472)H(10028)N(1728)O(2020)S(42)), an anti-IGF1R, fully human monoclonal antibody, alone and in combination with rapamycin (mTORC1 inhibitor) in Ewing's (SK-ES-1 and A673) and osteogenic (SJSA-1) sarcoma models. IGF1R was activated by IGF-1 but not by insulin in each sarcoma model. INSR was also activated by IGF-1 in the SJSA-1 and SK-ES-1 models, but not in the A673 model where insulin was the preferred INSR ligand. Ganitumab significantly inhibited the growth of SJSA-1 and SK-ES-1 xenografts; inhibition was associated with decreased IGF1R and Akt phosphorylation, reduced total IGF1R and bromodeoxyuridine detection, and increased caspase-3 expression. Ganitumab inhibited rapamycin-induced IGF1R, Akt, and glycogen synthase kinase-3β hyperphosphorylation in each sarcoma model. However, ganitumab in combination with rapamycin also resulted in a marked increase in INSR expression and activity in the SJSA-1 and A673 models. The in vivo efficacy of ganitumab in the two ganitumab-sensitive models (SJSA-1 and SK-ES-1) was significantly enhanced in combination with rapamycin. Our results support studying ganitumab in combination with mTORC1 inhibitors for the treatment of sarcomas and suggest that INSR signaling is an important mechanism of resistance to IGF1R blockade.

Topics: Animals; Antibiotics, Antineoplastic; Antibodies, Monoclonal; Antibodies, Monoclonal, Humanized; Antineoplastic Combined Chemotherapy Protocols; Bone Neoplasms; Caspase 3; Cell Line, Tumor; Cell Proliferation; Female; Humans; Insulin-Like Growth Factor I; Mice; Mice, Nude; Osteosarcoma; Phosphorylation; Receptor, IGF Type 1; Receptor, Insulin; Sarcoma, Ewing; Signal Transduction; Sirolimus; Xenograft Model Antitumor Assays

Rapamycin can inhibit tumor growth and angiogenesis in various human cancers. Cyclooxygenase 2 (COX-2) is involved in the angiogenic process. We hypothesized that the antiangiogenic effect of rapamycin may be mediated by suppression of COX-2.. Ewing sarcoma (ES) cells were implanted in athymic mice. Selected animals were treated with rapamycin for 5 weeks. Tumor vascularity was assessed by lectin perfusion angiography and immunohistochemistry. Phosphorylation of mammalian target of rapamycin pathway proteins was determined by Western blot analysis. Staining of COX-2 protein was determined by immunohistochemistry, and expression of COX-2 messenger RNA levels was assessed with quantitative real-time (RT) polymerase chain reaction.. Mean tumor weights were significantly reduced in the treated group (5.43 g +/- 1.43 SEM vs 0.49 g +/- 0.15 SEM, P < .003). There was abundant vasculature in the control group and blunted vascularity in the treated xenografts. The phosphorylation of p70s6k and Akt was not inhibited in the rapamycin-treated tumors. Cyclooxygenase 2 was suppressed in the treated xenografts at both the protein and messenger RNA levels.. Low-dose rapamycin inhibits tumor growth and angiogenesis in human ES without inhibiting the phosphorylation of p70s6k and Akt. Cyclooxygenase 2 levels are inhibited by low-dose treatment of ES with rapamycin. Cyclooxygenase 2 suppression may mediate the antiangiogenic effect of rapamycin in Ewing sarcoma.

Topics: Angiogenesis Inhibitors; Animals; Cell Line, Tumor; Cyclooxygenase 2; Disease Models, Animal; Female; Humans; Mice; Mice, Nude; Neovascularization, Pathologic; Sarcoma, Ewing; Signal Transduction; Sirolimus

Signaling through the type 1 insulin-like growth factor receptor (IGF-1R) occurs in many human cancers, including childhood sarcomas. As a consequence, targeting the IGF-1R has become a focus for cancer drug development. We examined the antitumor activity of CP-751,871, a human antibody that blocks IGF-1R ligand binding, alone and in combination with rapamycin against sarcoma cell lines in vitro and xenograft models in vivo. In Ewing sarcoma (EWS) cell lines, CP751,871 inhibited growth poorly (<50%), but prevented rapamycin-induced hyperphosphorylation of AKT(Ser473) and induced greater than additive apoptosis. Rapamycin treatment also increased secretion of IGF-1 resulting in phosphorylation of IGF-1R (Tyr1131) that was blocked by CP751,871. In vivo CP-751,871, rapamycin, or the combination were evaluated against EWS, osteosarcoma, and rhabdomyosarcoma xenografts. CP751871 induced significant growth inhibition [EFS(T/C) >2] in four models. Rapamycin induced significant growth inhibition [EFS(T/C) >2] in nine models. Although neither agent given alone caused tumor regressions, in combination, these agents had greater than additive activity against 5 of 13 xenografts and induced complete remissions in one model each of rhabdomyosarcoma and EWS, and in three of four osteosarcoma models. CP751,871 caused complete IGF-1R down-regulation, suppression of AKT phosphorylation, and dramatically suppressed tumor-derived vascular endothelial growth factor (VEGF) in some sarcoma xenografts. Rapamycin treatment did not markedly suppress VEGF in tumors and synergized only in tumor lines where VEGF was dramatically inhibited by CP751,871. These data suggest a model in which blockade of IGF-1R suppresses tumor-derived VEGF to a level where rapamycin can effectively suppress the response in vascular endothelial cells.

Topics: Animals; Antibodies, Monoclonal; Antineoplastic Combined Chemotherapy Protocols; Bone Neoplasms; Child; Drug Synergism; Female; Humans; Immunoglobulins, Intravenous; Mechanistic Target of Rapamycin Complex 1; Mice; Mice, SCID; Multiprotein Complexes; Osteosarcoma; Proteins; Receptor, IGF Type 1; Rhabdomyosarcoma; Sarcoma; Sarcoma, Ewing; Sirolimus; TOR Serine-Threonine Kinases; Transcription Factors; Vascular Endothelial Growth Factor A

To show the efficacy of targeting EWS/FLI-1 expression with a combination of specific antisense oligonucleotides and rapamycin for the control of Ewing's sarcoma (EWS) cell proliferation in vitro and the treatment of mouse tumor xenografts in vivo.. EWS cells were simultaneously exposed to EWS/FLI-1-specific antisense oligonucleotides and rapamycin for various time periods. After treatment, the following end points were monitored and evaluated: expression levels of the EWS/FLI-1 protein, cell proliferation, cell cycle distribution, apoptotic cell death, caspase activation, and tumor growth in EWS xenografts implanted in nude mice.. Simultaneous exposure of EWS cells in culture to an EWS/FLI-1-targeted suppression therapy using specific antisense oligonucleotides and rapamycin resulted in the activation of a caspase-dependent apoptotic process that involved the restoration of the transforming growth factor-beta-induced proapoptotic pathway. In vivo, individual administration of either antisense oligonucleotides or rapamycin significantly delayed tumor development, and the combined treatment with antisense oligonucleotides and rapamycin caused a considerably stronger inhibition of tumor growth.. Concurrent administration of EWS/FLI-1 antisense oligonucleotides and rapamycin efficiently induced the apoptotic death of EWS cells in culture through a process involving transforming growth factor-beta. In vivo experiments conclusively showed that the combined treatment with antisense oligonucleotides and rapamycin caused a significant inhibition of tumor growth in mice. These results provide proof of principle for further exploration of the potential of this combined therapeutic modality as a novel strategy for the treatment of tumors of the Ewing's sarcoma family.

Topics: Animals; Antibiotics, Antineoplastic; Antineoplastic Combined Chemotherapy Protocols; Apoptosis; Bone Neoplasms; Caspase 3; Caspase 7; Cell Proliferation; Combined Modality Therapy; Dose-Response Relationship, Drug; Gene Targeting; Genetic Therapy; Humans; Male; Mice; Mice, Nude; Oligonucleotides, Antisense; Oncogene Proteins, Fusion; Proto-Oncogene Protein c-fli-1; RNA-Binding Protein EWS; Sarcoma, Ewing; Sirolimus; Transcription Factors; Transforming Growth Factor beta1; Tumor Cells, Cultured; Xenograft Model Antitumor Assays

Ewing's sarcoma (ES) is the prototype of a family of tumors (ESFT) of neuroectodermal origin formed by small, round cells with limited neural differentiation, which arise most frequently within bones in children or adolescents. The proliferation of ESFT cells is highly dependent on the establishment of, and signaling through several growth factor-mediated autocrine loops. The mammalian target of rapamycin (mTOR) is a central regulator of translation and cell proliferation, involved in the cellular response to various nutritional, stress and mitogenic effectors. As mTOR has recently been associated with certain human cancers, we investigated the possibility that mTOR played a role in the regulation of ES cell proliferation. Results showed that ES cell lines carrying EWS/FLI-1 alleles of different types expressed different levels of total and phosphorylated mTOR protein. We demonstrate that rapamycin, an mTOR inhibitor, efficiently blocked the proliferation of all cell lines by promoting cell cycle arrest at the G1 phase. This was paralleled by the downregulation of the levels of the EWS/FLI-1 proteins, regardless of their fusion type, and the concomitant restoration of the expression of the TGF-beta type 2 receptor (TGFbeta RII), which is known to be repressed by several EWS-ETS fusion proteins. The expression of a rapamycin-resistant mTOR construct prevented both the proliferation blockade and the EWS/FLI-1 downregulation. These data demonstrate that mTOR signaling plays a central role in ES cell pathobiology and strongly suggest that the use of rapamycin as a cytostatic agent may be an efficient tool for the treatment of ES patients.

Topics: Alleles; Antibiotics, Antineoplastic; Apoptosis; Cell Division; Cell Line, Tumor; Down-Regulation; G1 Phase; Humans; Oncogene Proteins, Fusion; Phosphorylation; Protein Kinases; Protein Serine-Threonine Kinases; Proto-Oncogene Protein c-fli-1; Receptor, Transforming Growth Factor-beta Type II; Receptors, Transforming Growth Factor beta; RNA-Binding Protein EWS; Sarcoma, Ewing; Sirolimus; Time Factors; TOR Serine-Threonine Kinases; Transcription Factors