Combination of antiangiogenic therapy using the mTOR-inhibitor everolimus and low-dose chemotherapy for locally advanced and/or metastatic pancreatic cancer: a dose-finding study.

Pancreatic adenocarcinomas are associated with a poor survival prognosis. Besides curative surgical resection, only limited therapies with modest impact are available. New evidence suggests that the mammalian target of rapamycin pathway may be involved in the pathogenesis of neuroendocrine tumors, and breast and renal cell cancer. The phase I study described here was therefore designed to determine the maximum tolerated dose (MTD) and dose-limiting toxicity (DLT) of escalating doses of the mammalian target of rapamycin inhibitor everolimus in combination with gemcitabine in patients with advanced pancreatic cancer. Eligible patients had histologically confirmed locally advanced and/or metastatic pancreatic carcinoma and were administered 5 mg everolimus every second day (cohort 1, 2, 3) or 5 mg daily (cohort 4, 5) in combination with escalating low-dose gemcitabine. It was found that if two patients showed DLTs, MTD was reached and gemcitabine dose escalation was stopped at this level. Twenty-seven patients were enrolled in the study (cohort 1: n=3; cohort 2: n=4; cohort 3: n=6; cohort 4: n=7; cohort 5: n=7) and received a maximum 600 mg gemcitabine/week. In cohort 5, two of the six patients experienced DLTs (grade 3 liver toxicity lasting for>7 days). MTD was measured as 400 mg/m/week gemcitabine plus 5 mg/day everolimus. The MTD of a low-dose gemcitabine treatment in combination with everolimus was determined and no new safety concerns were identified in patients with advanced pancreatic cancer.

Impact of the spheroid model complexity on drug response.

Pharmaceutical investigators are searching for preclinical models closely resembling the original cancer and predicting clinical outcome. This study compares drug response of three in vitro 3D-drug screening models with different complexity. Tumor cell line spheroids were generated from the cell lines Caco-2, DLD-1, COLO 205, HT-29 and HCT-116, and treated with clinically relevant combination therapies, namely 5-FU/oxaliplatin (FO), 5-FU/irinotecan (FI) and the molecular drugs Cetuximab, Trastuzumab, Vorinostat and Everolimus. Treatment results were compared with spheroids originated from tumor cell lines (Caco-2, DLD-1) co-cultured with stromal cells (PBMCs, cancer-associated fibroblasts of colorectal origin) and spheroids directly prepared from colon cancer tissues. Different microenvironment compositions altered the tumor cell line spheroid response patterns. Adding PBMCs increased resistance to FO treatment by 10-15% in Caco-2 and DLD-1 spheroids but decreased resistance to FI by 16% in DLD-1 spheroids. Fibroblast co-cultures decreased resistance to FI in Caco-2 spheroids by 38% but had no impact on FO. Treatment of colon cancer tissue spheroids revealed three distinct response pattern subgroups not detectable in 3D cell lines models. The cancer tissue spheroid model mimics both tumor characteristics and the stromal microenvironment and therefore is an invaluable screening model for pharmaceutical drug development.

The immunosuppressant FTY720 inhibits tumor angiogenesis via the sphingosine 1-phosphate receptor 1.

FTY720, a sphingosine 1-phosphate (S1P) analog, acts as an immunosuppressant through trapping of T cells in secondary lymphoid tissues. FTY720 was also shown to prevent tumor growth and to inhibit vascular permeability. The MTT proliferation assay illustrated that endothelial cells are more susceptible to the anti-proliferative effect of FTY720 than Lewis lung carcinoma (LLC1) cells. In a spheroid angiogenesis model, FTY720 potently inhibited the sprouting activity of VEGF-A-stimulated endothelial cells even at concentrations that apparently had no anti-proliferative effect. Mechanistically, the anti-angiogenic effect of the general S1P receptor agonist FTY720 was mimicked by the specific S1P1 receptor agonist SEW2871. Moreover, the anti-angiogenic effect of FTY720 was abrogated in the presence of CXCR4-neutralizing antibodies. This indicates that the effect was at least in part mediated by the S1P1 receptor and involved transactivation of the CXCR4 chemokine receptor. Additionally, we could illustrate in a coculture spheroid model, employing endothelial and smooth muscle cells (SMCs), that the latter confer a strong protective effect regarding the action of FTY720 upon the endothelial cells. In a subcutaneous LLC1 tumor model, the anti-angiogenic capacity translated into a reduced tumor size in syngeneic C57BL/6 mice. Consistently, in the Matrigel plug in vivo assay, 10 mg/kg/d FTY720 resulted in a strong inhibition of angiogenesis as demonstrated by a reduced capillary density. Thus, in organ transplant patients, FTY720 may prove efficacious in preventing graft rejection as well as tumor development.