sirolimus and Intestinal-Neoplasms

There have been only five reported cases of primary posttransplant T-cell lymphoma. We report the first case associated with the use of sirolimus (Rapamycin, Wyeth-Ayerst, Philadelphia, PA). The patient, receiving prednisone, cyclosporine, and sirolimus treatment, developed ascites, diarrhea, and weight loss 7 months after his second renal transplant. Tissue obtained at laparotomy established the diagnosis of primary T-cell lymphoma. Latent membrane protein-1 for Epstein-Barr virus was negative, but in-site hybridization test for Epstein-Barr-encoded RNA was positive. Despite aggressive chemotherapy, the patient died 8 months posttransplant. This is the sixth reported case of primary intestinal posttransplant T-cell lymphoma, but it is the first case associated with the use of sirolimus. The incidence of posttransplant lymphoproliferative disease in patients receiving sirolimus should be studied.

Topics: Fatal Outcome; Humans; Immunosuppressive Agents; Intestinal Neoplasms; Kidney Transplantation; Lymphoma, T-Cell; Male; Middle Aged; Postoperative Complications; Sirolimus

Preclinical and clinical studies suggest synergistic activity between somatostatin analogues and mammalian target of rapamycin inhibitors. The activity and safety of everolimus was assessed in combination with octreotide long-acting repeatable (LAR) in patients with neuroendocrine tumors (NETs) of gastroenteropancreatic and lung origin.. This was a phase 2, multicenter trial using a Simon's 2-stage minimax design. Treatment-naive patients with advanced well-differentiated NETs of gastroenteropancreatic tract and lung origin received everolimus 10 mg daily, in combination with octreotide LAR 30 mg every 28 days. The primary endpoint was objective response rate (ORR).. A total of 50 patients (median age, 60.5 years) were enrolled. Primary tumor sites were: pancreas (14 patients), lung (11 patients), ileum (9 patients), jejunum and duodenum (2 patients), and unknown (14 patients). Thirteen patients (26%) had carcinoid syndrome. Treatment-related adverse events (AEs) were mostly grade 1 or 2; the only grade 4 AE was mucositis in 1 patient, whereas grade 3 AEs included skin rash in 1 case (2%), stomatitis in 4 cases (8%), and diarrhea in 11 cases (22%). The ORR was 18%; 2% of patients had a complete response (CR), 16% a partial response (PR) and 74% achieved stable disease (SD). All CRs and all PRs as well as 92% of SDs had a duration ≥ 6 months. The clinical benefit (CR+PR+SD) was 92%. At a median follow-up of 277 days, median time to progression and overall survival were not reached.. The everolimus-octreotide LAR combination was active and well tolerated in these previously treated patients with advanced NETs, suggesting a possible role as first-line treatment in patients with NET.

Topics: Adult; Aged; Antineoplastic Combined Chemotherapy Protocols; Everolimus; Female; Humans; Intestinal Neoplasms; Lung Neoplasms; Male; Middle Aged; Neuroendocrine Tumors; Octreotide; Pancreatic Neoplasms; Sirolimus; Stomach Neoplasms

A 7-year-old boy with a history of low-risk acute lymphoblastic leukemia developed multiple intussusceptions shortly after the end of maintenance therapy. Explorative laparotomy showed >10 polyps in the small intestine. Histologic examination revealed intestinal smooth muscle sarcomas associated with Epstein-Barr virus. The patient recovered well after partial cuneiform resection of the largest polyps and treatment with sirolimus. This case report indicates that these tumors may arise even after moderate transient immunosuppression and that association with acute lymphoblastic leukemia is possible although rarely described. We discuss the potential benefit of the mTor/Akt signal inhibitors as treatment for these tumors.

Topics: Child; Epstein-Barr Virus Infections; Herpesvirus 4, Human; Humans; Intestinal Neoplasms; Male; Muscle Neoplasms; Muscle, Smooth; Precursor B-Cell Lymphoblastic Leukemia-Lymphoma; Sarcoma; Sirolimus

Mechanistic target of rapamycin (mTOR) complex 1 (mTORC1) is frequently activated in cancers and can be counteracted with the clinical mTORC1 inhibitors everolimus and temsirolimus. Although mTORC1 and dual mTORC1/2 inhibitors are currently under development to treat various malignancies, the emergence of drug resistance has proven to be a major complication. Using the cis-Apc/Smad4 mouse model of locally invasive intestinal adenocarcinoma, we show that administration of everolimus or the dual mTORC1/2 inhibitor AZD8055 significantly reduces the growth of intestinal tumors. In contrast, although everolimus treatment at earlier phase of tumor progression delayed invasion of the tumors, both inhibitors exhibited little effect on blocking invasion of the tumors when administered later in their progression. Biochemical and immunohistochemical analyses revealed that treatment of cis-Apc/Smad4 mice with everolimus or AZD8055 induced marked increases in epidermal growth factor receptor (EGFR) and MEK/ERK signaling in tumor epithelial and stromal cells, respectively. Notably, co-administration of AZD8055 and the EGFR inhibitor erlotinib or the MEK inhibitor trametinib was sufficient to suppress tumor invasion in cis-Apc/Smad4 mice. These data indicate that mTOR inhibitor resistance in invasive intestinal tumors involves feedback signaling from both cancer epithelial and stromal cells, highlighting the role of tumor microenvironment in drug resistance, and support that simultaneous inhibition of mTOR and EGFR or MEK may be more effective in treating colon cancer.

Topics: Adenocarcinoma; Animals; Antineoplastic Agents; Blotting, Western; Cell Line, Tumor; Disease Models, Animal; Drug Resistance, Neoplasm; ErbB Receptors; Erlotinib Hydrochloride; Everolimus; Gene Expression Regulation, Neoplastic; HCT116 Cells; HT29 Cells; Humans; Intestinal Neoplasms; MAP Kinase Signaling System; Mice, 129 Strain; Mice, Inbred C57BL; Morpholines; Neoplasm Invasiveness; Sirolimus; TOR Serine-Threonine Kinases; Tumor Microenvironment

Therapeutic targeting of tumor angiogenesis with VEGF inhibitors results in demonstrable, but transitory efficacy in certain human tumors and mouse models of cancer, limited by unconventional forms of adaptive/evasive resistance. In one such mouse model, potent angiogenesis inhibitors elicit compartmental reorganization of cancer cells around remaining blood vessels. The glucose and lactate transporters GLUT1 and MCT4 are induced in distal hypoxic cells in a HIF1α-dependent fashion, indicative of glycolysis. Tumor cells proximal to blood vessels instead express the lactate transporter MCT1, and p-S6, the latter reflecting mTOR signaling. Normoxic cancer cells import and metabolize lactate, resulting in upregulation of mTOR signaling via glutamine metabolism enhanced by lactate catabolism. Thus, metabolic symbiosis is established in the face of angiogenesis inhibition, whereby hypoxic cancer cells import glucose and export lactate, while normoxic cells import and catabolize lactate. mTOR signaling inhibition disrupts this metabolic symbiosis, associated with upregulation of the glucose transporter GLUT2.

Topics: Angiogenesis Inhibitors; Animals; Axitinib; Cell Line, Tumor; Drug Resistance, Neoplasm; Gene Expression Regulation, Neoplastic; Glucose; Glutamine; Glycolysis; Humans; Imidazoles; Indazoles; Indoles; Intestinal Neoplasms; Lactic Acid; Membrane Transport Proteins; Mice; Models, Biological; Neuroendocrine Tumors; Pancreatic Neoplasms; Pyrroles; Signal Transduction; Sirolimus; Stomach Neoplasms; Sunitinib; TOR Serine-Threonine Kinases; Up-Regulation

Neuroendocrine tumors (NETs) are a rare diverse group of malignancies occurring most commonly in the gastroenteropancreatic system and the lungs. The incidence of NETs is increasing worldwide; median survival for patients with metastatic NETs is 5-65 months. A growing body of evidence shows survival benefit in patients with advanced NETs (gastroenteropancreatic and lung) treated with mTOR inhibitor everolimus, with improvement in survival being demonstrated in the clinical trial and real-world setting. Everolimus has been shown to have a manageable safety profile, with the most common adverse events being stomatitis, rash, diarrhea, fatigue and infections. Due to the rarity of the condition, there are challenges in conducting clinical trials in these patients. Further research is required to clarify the role of adjuvant therapy, treatment sequencing and the use of multimodality treatments.

Topics: Clinical Trials as Topic; Combined Modality Therapy; Everolimus; Humans; Intestinal Neoplasms; Neoplasm Metastasis; Neuroendocrine Tumors; Pancreatic Neoplasms; Protein Kinase Inhibitors; Respiratory System; Sirolimus; Stomach Neoplasms

Neuroendocrine tumors of the gastroenteropancreatic tract remain a difficult array of neoplasia to treat. Treatment of advanced and metastatic gastroenteropancreatic neuroendocrine tumors has traditionally been difficult with few systemic treatment options. In 2011, two new targeted therapies, everolimus and sunitinib were approved for treatment of pancreatic neuroendocrine tumor. The approval of these agents led to an enhanced interest in exploring novel agents. This can be evidenced by the fact that this is the first year that ASCO assembled related abstracts under a separate title of neuroendocrine tumor. The annual American Society of Clinical Oncology (ASCO) conference in 2013 presented four abstracts (#4030, #4031, #4032, #4136) that shed light on new therapeutic options that help target the unique pathways involved in these neuroendocrine malignancies.

Topics: Antibodies, Monoclonal, Humanized; Antineoplastic Combined Chemotherapy Protocols; Bevacizumab; Everolimus; Humans; Indoles; Intestinal Neoplasms; Neuroendocrine Tumors; Octreotide; Pancreatic Neoplasms; Pyrroles; Sirolimus; Stomach Neoplasms; Sunitinib; Treatment Outcome

Although (177)Lu-octreotate is an effective treatment for patients with gastroenteropancreatic neuroendocrine tumors (GEP-NETs), some patients will fail or develop disease progression necessitating further treatment. We examined whether the safety and efficacy of everolimus after prior treatment with (177)Lu-octreotate is different from the published safety profile of everolimus in GEP-NETs. In this multicenter study, 24 GEP-NET patients were included. Adverse events were assessed according to the National Cancer Institute Common Terminology Criteria for Adverse Events (CTCAE), version 3.0. Tumor response was measured according to the Response Evaluation Criteria in Solid Tumors (RECIST), version 1.0. Major clinical adverse events (grade 3 or 4) during treatment with everolimus were hyperglycemia (20.8%), fatigue (8.3%), thrombocytopenia (8.3%), and elevated alanine transaminase levels (8.3%). By radiological review, there were four partial responses (16.7%), five patients (62.5%) with stable disease, and three patients (12.5%) with progressive disease. For two patients (8.3%), no data on tumor response were available. Median progression-free survival (PFS) was 13.1 months (95% CI, 11.5-21.2). Median PFS of the current study was longer when compared with the RADIANT-3 trial (13.1 vs 11.4 months) and shorter when compared with the RADIANT-1 trial (13.1 vs 16.7 months). In conclusion, the safety profile of everolimus is not influenced by previous treatment with peptide receptor radiotherapy.

Topics: Adult; Aged; Bone Neoplasms; Everolimus; Female; Follow-Up Studies; Humans; Immunosuppressive Agents; Intestinal Neoplasms; Liver Neoplasms; Lutetium; Lymphatic Metastasis; Male; Middle Aged; Neoplasm Staging; Neuroendocrine Tumors; Octreotide; Pancreatic Neoplasms; Prognosis; Retrospective Studies; Safety; Sirolimus; Stomach Neoplasms; Survival Rate

Chromogranin A is a neuroendocrine secretory product and its loss is a feature of malignant NEN de-differentiation. We hypothesized that chromogranin A fragments were differentially expressed during NEN metastasis and played a role in the regulation of NEN proliferation.. Chromogranin A mRNA (PCR) and protein (ELISA/western blot) were studied in 10 normal human mucosa, 5 enterochromaffin cell preparations, 26 small intestinal NEN primaries and 9 liver metastases. Cell viability (WST-1 assay), proliferation (bromodeoxyuridine ELISA) and expression of AKT/AKT-P (CASE ELISA/western blot) in response to chromogranin A silencing, inhibition of prohormone convertase and mTOR inhibition (RAD001/AKT antisense) as well as different chromogranin A fragments were examined in 4 SI-NEN cell lines.. Chromogranin A mRNA and protein levels were increased (37-340 fold, p<0.0001) in small intestinal NENs compared to normal enterochromaffin cells. Western blot identified chromogranin A-associated processing bands including vasostatin in small intestinal NENs as well as up-regulated expression of prohormone convertase in metastases. Proliferation in small intestinal NEN cell lines was decreased by silencing chromogranin A as well as by inhibition of prohormone convertase (p<0.05). This inhibition also decreased secretion of chromogranin A (p<0.05) and 5-HT (p<0.05) as well as expression of vasostatin. Metastatic small intestinal NEN cell lines were stimulated (50-80%, p<0.05) and AKT phosphorylated (Ser473: p<0.05) by vasostatin I, which was completely reversed by RAD001 (p<0.01) and AKT antisense (p<0.05) while chromostatin inhibited proliferation (~50%, p<0.05).. Chromogranin A was differentially regulated in primary and metastatic small intestinal NENs and cell lines. Chromogranin A fragments regulated metastatic small intestinal NEN proliferation via the AKT pathway indicating that CgA plays a far more complex role in the biology of these tumors than previously considered.

Topics: Calreticulin; Cell Line, Tumor; Cell Proliferation; Cell Survival; Chromogranin A; Everolimus; Gene Expression Regulation, Neoplastic; Humans; Intestinal Neoplasms; Liver Neoplasms; Neuroendocrine Tumors; Peptide Fragments; Phosphorylation; Proprotein Convertases; Proto-Oncogene Proteins c-akt; RNA, Messenger; RNA, Small Interfering; Signal Transduction; Sirolimus; TOR Serine-Threonine Kinases

While the range of therapeutic options for well-differentiated gastroenteropancreatic neuroendocrine tumors has recently increased with the emergence of targeted therapies, such as mTOR inhibitors, there is no recent progress in the treatment of poorly differentiated neuroendocrine carcinomas (PDNECs). Since PDNECs have been shown to strongly express mTOR pathway components, the aim of the present study was to assess the antitumor effect of the mTOR inhibitor everolimus in preclinical models of PDNECs.. The expression of mTOR pathway components and their response to everolimus were assessed in two neuroendocrine cell lines: STC-1 and GluTag. A xenograft model of intrahepatic dissemination in the nude mouse, based on the intrasplenic injection of either STC-1 and GluTag tumor cells, was used. Animals were started on everolimus treatment 3 days after injection. The effects of treatment on tumor growth, proliferative capacities, apoptosis and in situ expression of mTOR pathway components were assessed.. The expression of mTOR pathway components was comparable in STC-1 and GluTag cells and in human PDNECs and could be inhibited in vitro by everolimus. In vivo, the tumor volume of STC-1 and GluTag xenografts was significantly reduced in treated animals (6.05 ± 1.84% as compared to 21.76 ± 3.88% in controls). Everolimus treatment also induced a significant decrease in Ki67 index and in the phosphorylation levels of the two major effectors of mTOR, p70S6K and 4E-BP1.. Our experimental data suggest that mTOR inhibition could be considered a therapeutic option for high-grade gastroenteropancreatic neuroendocrine tumors.

Topics: Adult; Aged; Animals; Antineoplastic Agents; Cell Line, Tumor; Everolimus; Female; Humans; Intestinal Neoplasms; Male; Mice; Mice, Nude; Middle Aged; Neuroendocrine Tumors; Pancreatic Neoplasms; Signal Transduction; Sirolimus; Stomach Neoplasms; TOR Serine-Threonine Kinases; Xenograft Model Antitumor Assays

The mammalian target of rapamycin (mTOR) inhibitors, such as rapalogues, are a promising new tool for the treatment of metastatic gastroenteropancreatic endocrine tumors. However, their mechanisms of action remain to be established. We used two murine intestinal endocrine tumoral cell lines, STC-1 and GLUTag, to evaluate the antitumor effects of rapamycin in vitro and in vivo in a preclinical model of liver endocrine metastases. In vitro, rapamycin inhibited the proliferation of cells in the basal state and after stimulation by insulin-like growth factor-1. Simultaneously, p70S6 kinase and 4EBP1 phosphorylation was inhibited. In vivo, rapamycin substantially inhibited the intrahepatic growth of STC-1 cells, irrespectively of the timing of its administration and even when the treatment was administered after cell intrahepatic engraftment. In addition, treated animals had significantly prolonged survival (mean survival time: 47.7 days in treated animals versus 31.8 days in controls) and better clinical status. Rapamycin treatment was associated with a significant decrease in mitotic index and in intratumoral vascular density within STC-1 tumors. Furthermore, the antitumoral effect obtained after treatment with a combination of rapamycin and phosphatidylinositol 3-kinase (PI3K) inhibitor LY294002 was more significant than with rapamycin alone in both cell lines. Our results suggest that the antitumor efficacy of rapamycin in neuroendocrine tumors results from a combination of antiproliferative and antiangiogenic effects. Interestingly, a more potent antitumor efficiency could be obtained by simultaneously targeting several levels of the PI3K/mTOR pathway.

Topics: Animals; Antibiotics, Antineoplastic; Antineoplastic Combined Chemotherapy Protocols; Carcinoma, Neuroendocrine; Cell Line, Tumor; Cell Proliferation; Chromones; Intestinal Neoplasms; Mice; Morpholines; Phosphoinositide-3 Kinase Inhibitors; Phosphorylation; Protein Kinase Inhibitors; Sirolimus; TOR Serine-Threonine Kinases

Treatment of small intestinal neuroendocrine tumors (SINETs) with mammalian target of rapamycin (mTOR) inhibitors alone or with somatostatin analogs has been proposed as effective therapy, because both agents have been reported to exhibit antiproliferative activity. Because adenocarcinomas escape mTOR inhibition, we examined whether the escape phenomenon occurred in SINETs and whether usage of somatostatin analogs with mTOR inhibitors surmounted loss of inhibition.. The effects of the somatostatin analog octreotide (OCT), the mTOR inhibitor RAD001 (RAD), or the combination were evaluated in SINET cell lines (KRJ-I, H-STS) using cell viability assays, western blotting, enzyme-linked immunosorbent assay, and reverse-transcription polymerase chain reaction to assess antiproliferative signaling pathways and feedback regulation.. RAD (10(-9) M) incompletely decreased cell viability (-40% to +15%); growth escape (P < .001) was noted at 72 hours in both cell lines. Phosphorylated (p)mTOR/mTOR and pp70S6K/p70S6K ratios were decreased but were associated with increases in phosphorylated extracellular signal-regulated kinase (pERK)/ERK and pAKT/AKT in both cell lines, whereas phosphorylated insulin-like growth factor 1 receptor (pIGF-1R)/IGF-1R levels were elevated only in H-STS cells. Increased (P < .05) transcript levels for AKT1, MAPK, mTOR, IGF-1R, IGF-1, and TGFβ1 were evident. OCT (10(-6) M) itself had no significant effect on growth signaling in either cell line. An antiproliferative effect (66 ± 5%) using OCT+RAD was only noted in the KRJ-I cells (P < .05).. SINET treatment with the mTOR inhibitor RAD had no antiproliferative effect based on activation of pAKT and pERK1/2. A combinatorial approach using OCT and RAD failed to overcome this escape phenomenon. However, differences in RAD response rates in individual NET cell lines suggested that pretreatment identification of different tumor sensitivity to mTOR inhibitors could provide the basis for individualized treatment.

Topics: Cell Line, Tumor; Cell Proliferation; Cell Survival; Everolimus; Humans; Intestinal Neoplasms; Intestine, Small; Mitogen-Activated Protein Kinase 1; Mitogen-Activated Protein Kinase 3; Neuroendocrine Tumors; Octreotide; Phosphatidylinositol 3-Kinases; Phosphorylation; Protein Kinase Inhibitors; Proto-Oncogene Proteins c-akt; Signal Transduction; Sirolimus; TOR Serine-Threonine Kinases

The adenomatous polyposis coli (APC) gene is mutated in familial adenomatous polyposis. Mice with a heterozygous APC(Min) mutation develop multiple intestinal neoplasia (Min) leading to premature death. Early in colorectal carcinogenesis, APC(Min/+) mice show enhanced Akt-mammalian target of rapamycin (mTOR) signaling, which is paralleled by upregulation of oncogenic K(+) channels. In this study, we tested the effect of mTOR inhibition with rapamycin on tumor formation in APC(Min/+) mice and evaluated ion channel regulation. We found that continuous long-term rapamycin treatment of APC(Min/+) mice dramatically inhibits intestinal neoplasia. Moreover, although untreated APC(Min/+) mice lose weight, experience intestinal bleeding and succumb to multiple neoplasia by 22.3+/-1.4 weeks of age, mice treated with rapamycin maintain stable weight and survive long term (39.6+/-3.4 weeks), with more than 30% surviving >1 year. Impressively, abnormalities in colonic electrolyte transport typical for APC(Min/+) mice are abolished, along with the suppression of epithelial Na(+) channel (ENaC) and oncogenic K(+) ion channels BK, Elk1 and Erg1, both functionally and at mRNA levels. These results show that continuous prophylaxis by rapamycin markedly inhibits the development of APC mutation-related polyposis, and suggest a novel contributing mechanism of action through the blockade of intestinal oncogenic ion channels.

Topics: Adenomatous Polyposis Coli Protein; Animals; Codon, Nonsense; Immunosuppressive Agents; Intestinal Mucosa; Intestinal Neoplasms; Intestinal Polyps; Intestines; Intracellular Signaling Peptides and Proteins; Ion Channels; Mice; Protein Serine-Threonine Kinases; Sirolimus; TOR Serine-Threonine Kinases; Weight Loss

Activation of the mTORC1 pathway has been implicated in many types of cancer, and several mTORC1 inhibitors are currently under clinical trials for treating various cancer patients. Notably, Temsirolimus has recently been approved for treatment of advanced renal cell carcinoma. However, the role of mTORC1 pathway in colorectal tumorigenesis remains largely unknown. We have recently found that the mTORC1 pathway is activated in intestinal adenomas of Apc mutant mice, accompanied by an elevated level of mTOR protein, and that treatment with RAD001, an mTORC1 inhibitor, suppresses the growth of these polyps. Our results suggest an important role of mTORC1 pathway in colorectal cancer, as well as a therapeutic possibility for mTORC1 inhibitors in its treatment.

Topics: Adenoma; Animals; Everolimus; Humans; Intestinal Neoplasms; Mechanistic Target of Rapamycin Complex 1; Mice; Models, Biological; Multiprotein Complexes; Proteins; Signal Transduction; Sirolimus; TOR Serine-Threonine Kinases; Transcription Factors; Wnt Proteins

The mammalian target of rapamycin (mTOR) has become an interesting target for cancer therapy through its influence on oncogenic signals, which involve phosphatidylinositol-3-kinase and hypoxia-inducible factor-1alpha (HIF-1alpha). Since mTOR is an upstream regulator of HIF-1alpha, a key mediator of gastric cancer growth and angiogenesis, we investigated mTOR activation in human gastric adenocarcinoma specimens and determined whether rapamycin could inhibit gastric cancer growth in mice. Expression of phospho-mTOR was assessed by immunohistochemical analyses of human tissues. For in vitro studies, human gastric cancer cell lines were used to determine S6K1, 4E-BP-1 and HIF-1alpha activation and cancer cell motility upon rapamycin treatment. Effects of rapamycin on tumor growth and angiogenesis in vivo were assessed in both a subcutaneous tumor model and in an experimental model with orthotopically grown tumors. Mice received either rapamycin (0.5 mg/kg/day or 1.5 mg/kg/day) or diluent per intra-peritoneal injections. In addition, antiangiogenic effects were monitored in vivo using a dorsal-skin-fold chamber model. Immunohistochemical analyses showed strong expression of phospho-mTOR in 60% of intestinal- and 64% of diffuse-type human gastric adenocarcinomas. In vitro, rapamycin-treatment effectively blocked S6K1, 4E-BP-1 and HIF-1alpha activation, and significantly impaired tumor cell migration. In vivo, rapamycin-treatment led to significant inhibition of subcutaneous tumor growth, decreased CD31-positive vessel area and reduced tumor cell proliferation. Similar significant results were obtained in an orthotopic model of gastric cancer. In the dorsal-skin-fold chamber model, rapamycin-treatment significantly inhibited tumor vascularization in vivo. In conclusion, mTOR is frequently activated in human gastric cancer and represents a promising new molecular target for therapy.

Topics: Adenocarcinoma; Animals; Antibiotics, Antineoplastic; Cell Hypoxia; Cell Line, Tumor; Cell Movement; Cell Proliferation; Disease Models, Animal; Humans; Hypoxia-Inducible Factor 1, alpha Subunit; Intestinal Neoplasms; Male; Mice; Mice, Inbred BALB C; Mice, Nude; Neovascularization, Pathologic; Phosphatidylinositol 3-Kinases; Phosphorylation; Protein Kinases; Ribosomal Protein S6 Kinases, 70-kDa; Signal Transduction; Sirolimus; Stomach Neoplasms; Survival Rate; TOR Serine-Threonine Kinases; Vascular Endothelial Growth Factor A