monomethyl-auristatin-e and Neuroendocrine-Tumors

As patient-derived xenografts and other preclinical models of neuroendocrine tumors for testing personalized therapeutics are lacking, we have developed a perfused, 3D bioreactor model to culture tumor surrogates from patient-derived neuroendocrine tumors. This work evaluates the duration of surrogate culture and surrogate response to a novel antibody-drug conjugate.. Twenty-seven patient-derived neuroendocrine tumors were cultured. Histologic sections of a pancreatic neuroendocrine tumor xenograft (BON-1) tumor were assessed for SSTR2 expression before tumor implantation into 2 bioreactors. One surrogate was treated with an antibody-drug conjugate composed of an anti-mitotic Monomethyl auristatin-E linked to a somatostatin receptor 2 antibody. Viability and therapeutic response were assessed by pre-imaging incubation with IR-783 and the RealTime-Glo AnnexinV Apoptosis and Necrosis Assay (Promega Corporation, Madison, WI) over 6 days. A primary human pancreatic neuroendocrine tumor was evaluated similarly.. Mean surrogate growth duration was 34.8 days. Treated BON-1 surrogates exhibited less proliferation (1.2 vs 1.9-fold) and greater apoptosis (1.5 vs 1.1-fold) than controls, whereas treated patient-derived neuroendocrine tumor bioreactors exhibited greater degrees of apoptosis (13- vs 9-fold) and necrosis (2.5- vs 1.6-fold).. Patient-derived neuroendocrine tumor surrogates can be cultured reliably within the bioreactor. This model can be used to evaluate the efficacy of antibody-guided chemotherapy ex vivo and may be useful for predicting clinical responses.

Topics: Animals; Antineoplastic Agents, Immunological; Apoptosis; Bioreactors; Cell Proliferation; Drug Screening Assays, Antitumor; Humans; Immunoconjugates; Male; Mice; Molecular Targeted Therapy; Neuroendocrine Tumors; Oligopeptides; Pancreatic Neoplasms; Primary Cell Culture; Receptors, Somatostatin; Reproducibility of Results; Tumor Cells, Cultured

Surgical resection is the only cure for neuroendocrine tumors (NETs). However, widespread metastases have already occured by the time of initial diagnosis in many cases making complete surgical removal impossible. We developed a recombinant heavy-chain receptor binding domain (rHCR) of botulinum neurotoxin type A that can specifically target synaptic vesicle 2 (SV2), a surface receptor abundantly expressed in multiple neuroendocrine tumors. Expression of neuroendocrine differentiation markers chromogranin A (CgA) and achaete-scute complex 1 (ASCL1) were signficantly reduced when treated with rHCR. rHCR conjugated to the antimitotic agent monomethyl auristatin E (MMAE) significantly suppressed proliferation of pancreatic carcinoid (BON) and medullary thyroid cancer cells (MZ) at concentrations of 500 and 300 nM respectively, while no growth suppression was observed in pulmonary fibroblasts and cortical neuron control cell lines. In vivo, rHCR-MMAE significantly reduced tumor volume in mouse xenografts with no observed adverse effects. These data suggest recombinant HCR (rHCR) of BoNT/A preferentially targets neuroendocrine cancer without the neurotoxicity of the full BoNT/A and that SV2 is a specific and promising target for delivering drugs to neuroendocrine tumors.

Topics: Animals; Apoptosis; Botulinum Toxins, Type A; Cell Line, Tumor; Cell Proliferation; Disease Models, Animal; Humans; Mice; Neuroendocrine Tumors; Neuromuscular Agents; Oligopeptides