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AAVP displaying octreotide for ligand-directed therapeutic transgene delivery in neuroendocrine tumors of the pancreas.

ABSTRACT: Patients with inoperable or unresectable pancreatic neuroendocrine tumors (NETs) have limited treatment options. These rare human tumors often express somatostatin receptors (SSTRs) and thus are clinically responsive to certain relatively stable somatostatin analogs, such as octreotide. Unfortunately, however, this tumor response is generally short-lived. Here we designed a hybrid adeno-associated virus and phage (AAVP) vector displaying biologically active octreotide on the viral surface for ligand-directed delivery, cell internalization, and transduction of an apoptosis-promoting tumor necrosis factor (TNF) transgene specifically to NETs. These functional attributes of AAVP-TNF particles displaying the octreotide peptide motif (termed Oct-AAVP-TNF) were confirmed in vitro, in SSTR type 2-expressing NET cells, and in vivo using cohorts of pancreatic NET-bearing Men1 tumor-suppressor gene KO mice, a transgenic model of functioning (i.e., insulin-secreting) tumors that genetically and clinically recapitulates the human disease. Finally, preclinical imaging and therapeutic experiments with pancreatic NET-bearing mice demonstrated that Oct-AAVP-TNF lowered tumor metabolism and insulin secretion, reduced tumor size, and improved mouse survival. Taken together, these proof-of-concept results establish Oct-AAVP-TNF as a strong therapeutic candidate for patients with NETs of the pancreas. More broadly, the demonstration that a known, short, biologically active motif can direct tumor targeting and receptor-mediated internalization of AAVP particles may streamline the potential utility of myriad other short peptide motifs and provide a blueprint for therapeutic applications in a variety of cancers and perhaps many nonmalignant diseases as well.

SUBMITTER: Smith TL

PROVIDER: S-EPMC4780640 | biostudies-other | 2016 Mar

REPOSITORIES: biostudies-other

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Project description:Lessons learnedRate of progression-free survival at a particular point in time, i.e., a landmark analysis, is a difficult endpoint for a heterogenous malignancy such as neuroendocrine cancer.Landmark analyses can also be complicated by evolution in the standard of care during the conduct of a clinical trial.Improvements in biomarker development would be useful in developing future clinical trials in NET to better tailor individualized therapies and assess for possible efficacy endpoints.BackgroundNeuroendocrine tumors (NETs) are rare malignancies of the gastrointestinal (GI) tract that are highly vascularized and overexpress vascular-endothelial growth factor (VEGF). Sunitinib has demonstrated efficacy in the pancreatic subset of NET. This study explored the activity of another oral VEGF inhibitor, AMG 706 or motesanib, a multikinase inhibitor that targets receptor tyrosine kinases, including VEGFR1, VEGFR2, VEGFR3, KIT, RET, and PDGFR (IC50s = 2, 3, 6, 8, 59, and 84 nM, respectively).MethodsThis was a single-arm, first-line, phase II study run through the Eastern Cooperative Oncology Group. Patients with low-grade NET (as defined by central confirmation of Ki-67 of 0%-2%) were administered a flat dose of 125 mg per day orally combined with octreotide long acting-repeatable (LAR) for patients who had been on a stable dose. The primary objective was to determine the 4-month progression-free survival (PFS).ResultsForty-four patients were evaluated per protocol. The 4-month PFS was 78.5%. The partial response rate was 13.6% (6/44), stable disease was 54.5% (24/44), 9.1% (4/44) had progressive disease, and 10/44 were not evaluable for response. Common toxicities included fatigue, hypertension, nausea, and headache, and most were grade 1-2. Median PFS was 8.7 months, and overall survival was 27.5 months.ConclusionMotesanib (AMG 706) demonstrated a 4-month PFS that met the per-protocol definition of efficacy. Fatigue and hypertension were the most common toxicities, and few grade 3-4 toxicities were encountered. The progression-free survival of 8.7 months in all NETs merits further study.

Project description:The management of neuroendocrine tumors (NETs) is very variable, depending on many specific aspects, such as the type of tumor, spread and patient general health. Several advances have been made with the newly developed somatostatin analogues to cure this type of malignancies. Somatostain analogues such as octreotide have been used in clinic to treat patients with neuroendocrine tumors (NETs). However, the molecular mechanism leading either to successful therapy or acquired resistance to the analogues is still to large extent unclear. Patients develop drugs resistance during a long term treatment. Therefore, to identify the pivotal regulatory genes involved in the development of drug resistance is an actual challenge. We studied five human neuroendocrine tumor cell lines, CNDT2.5, KRJ1, QGP-1, NCI H720 and NCI H727. We also investigated a long-term treated CNDT2.5 by using octreotide. We performed gene expression profiling in all the human neuroendocrine cell lines. Keywords: Gene Expression profiling, treatment comparison We investigated 5 human neuroendocrine cell lines, CNDT2.5 and KRJ1, established from ileum NETs, QGP1 by a pancreatic NET, NCI H720 and NCI H727 from bronchopulmonary NETs. CNDT2.5 cell were constantly treated with 1M-BM-5M octreotide for 10 and 16 months. We isolated total RNA (Ambion, PARISM-bM-^DM-" Kit) from 5 WT cell lines and CNDT2.5 treated with octreotide (Santostatin, Novartis). Total RNA was hybridized onto the Affymetrix Human Gene 1.0 ST Array by Affymetrix Uppsala Platform, UU. SE (Uppsala, Sweden). We first wanted to verify whether the different cell lines may become reliable models to study neuroendocrine signaling pathways. The main objective of this project aimed at understanding the mechanisms by which octrotide (Sandostatin, Novartis) alter cellular growth and differentiation of CNDT2.5 cells. We therefore focused on intermediate (10 months) and long stimulation (16 months) events triggered by sandostatin, which lead variation of CNDT.2.5 cells gene expression to identify potential pivotal genes involved in the development of drug resistance in neuroendocrine cells.

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AAVP displaying octreotide for ligand-directed therapeutic transgene delivery in neuroendocrine tumors of the pancreas.

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