EPIC: phase III trial of cetuximab plus irinotecan after fluoropyrimidine and oxaliplatin failure in patients with metastatic colorectal cancer.

PURPOSE: To determine whether adding cetuximab to irinotecan prolongs survival in patients with metastatic colorectal cancer (mCRC) previously treated with fluoropyrimidine and oxaliplatin. PATIENTS AND METHODS: This multicenter, open-label, phase III study randomly assigned 1,298 patients with epidermal growth factor receptor-expressing mCRC who had experienced first-line fluoropyrimidine and oxaliplatin treatment failure to cetuximab (400 mg/m(2) day 1 followed by 250 mg/m(2) weekly) plus irinotecan (350 mg/m(2) every 3 weeks) or irinotecan alone. Primary end point was overall survival (OS); secondary end points included progression-free survival (PFS), response rate (RR), and quality of life (QOL). RESULTS: Median OS was comparable between treatments: 10.7 months (95% CI, 9.6 to 11.3) with cetuximab/irinotecan and 10.0 months (95% CI, 9.1 to 11.3) with irinotecan alone (hazard ratio [HR], 0.975; 95% CI, 0.854 to 1.114; P = .71). This lack of difference may have been due to post-trial therapy: 46.9% of patients assigned to irinotecan eventually received cetuximab (87.2% of those who did, received it with irinotecan). Cetuximab added to irinotecan significantly improved PFS (median, 4.0 v 2.6 months; HR, 0.692; 95% CI, 0.617 to 0.776; P

Phase II trial of cetuximab in combination with fluorouracil, leucovorin, and oxaliplatin in the first-line treatment of metastatic colorectal cancer.

PURPOSE: This phase II study investigated the efficacy and safety of cetuximab combined with standard oxaliplatin-based chemotherapy (infusional fluorouracil, leucovorin, and oxaliplatin [FOLFOX-4]) in the first-line treatment of epidermal growth factor receptor-expressing metastatic colorectal cancer (mCRC). PATIENTS AND METHODS: The activity of cetuximab plus oxaliplatin was investigated in colon cancer cell lines and xenograft models. In the clinical study, patients with mCRC received on day 1 of a 14 day cycle, cetuximab (initial dose 400 mg/m(2) during week 1, then 250 mg/m(2) weekly) followed by FOLFOX-4 (oxaliplatin 85 mg/m(2) on day 1; leucovorin 200 mg/m(2) on days 1 and 2, followed by fluorouracil 400 mg/m(2) bolus then 600 mg/m(2) intravenous infusion during 22 hours on days 1 and 2). RESULTS: The preclinical studies confirmed the supra-additive activity of cetuximab to oxaliplatin. In the clinical study, 43 patients were included, with a median age of 65 years (range, 43 to 78 years). Response rates (RRs) were 79% (unconfirmed) and 72% (confirmed), with 95% disease control. Median progression-free survival (mPFS) and median duration of response were 12.3 and 10.8 months, respectively. Ten patients (23%) underwent resection with curative intent of previously unresectable metastases. After a median follow-up of 30.5 months, median overall survival (mOS) was 30.0 months. Cetuximab did not increase the characteristic toxicity of FOLFOX-4 and was generally well tolerated. CONCLUSION: Cetuximab in combination with FOLFOX-4 is a highly active first-line treatment for mCRC, showing encouraging RR, mPFS, and mOS values. The treatment resulted in a high resectability rate, which could potentially result in an improved cure rate. This combination is under phase III development.

Therapeutic efficacy of endostatin exhibits a biphasic dose-response curve.

We show here that recombinant endostatin protein has a biphasic effect on the inhibition of endothelial cell migration in vitro. In tumor-bearing animals, there is a similar biphasic effect on the inhibition of tumor growth and on circulating endothelial cells after once-daily s.c. injections. This biphasic effect is revealed as a U-shaped curve in which efficacy is optimal between very low and very high doses depending on the tumor type. This result may be applicable to other inhibitors of endothelial growth and to angiogenesis. Furthermore, these results have important implications for clinicians who administer angiogenesis inhibitors for cancer or other angiogenesis-dependent diseases. When these results are taken together with two previous reports of angiogenesis inhibitors with a U-shaped dose-response, they suggest that other regulators of endothelial growth may display a similar pattern.

A peptide trivalent arsenical inhibits tumor angiogenesis by perturbing mitochondrial function in angiogenic endothelial cells.

Mitochondria are the powerhouse of the cell and their disruption leads to cell death. We have used a peptide trivalent arsenical, 4-(N-(S-glutathionylacetyl)amino) phenylarsenoxide (GSAO), to inactivate the adenine nucleotide translocator (ANT) that exchanges matrix ATP for cytosolic ADP across the inner mitochondrial membrane and is the key component of the mitochondrial permeability transition pore (MPTP). GSAO triggered Ca(2+)-dependent MPTP opening by crosslinking Cys(160) and Cys(257) of ANT. GSAO treatment caused a concentration-dependent increase in superoxide levels, ATP depletion, mitochondrial depolarization, and apoptosis in proliferating, but not growth-quiescent, endothelial cells. Endothelial cell proliferation drives new blood vessel formation, or angiogenesis. GSAO inhibited angiogenesis in the chick chorioallantoic membrane and in solid tumors in mice. Consequently, GSAO inhibited tumor growth in mice with no apparent toxicity at efficacious doses.

Treatment of human pancreatic cancer in mice with angiogenic inhibitors.

Tumor growth is dependent on the balance of positive and negative regulators of angiogenesis. Antiangiogenic compounds inhibit endothelial cell biology in vitro and angiogenesis in vivo. Therefore antiangiogenic therapy presumes to be an effective treatment for pancreatic cancer. We wanted to determine the effect of antiangiogenic therapy on the growth of human pancreatic cancer in a mouse model. The angiogenesis inhibitors TNP-470 and antiangiogenic antithrombin III (aaATIII) were tested in vitro for their ability to inhibit endothelial cell proliferation. These inhibitors, along with the known antiangiogenic molecule endostatin, were then employed to treat two different primary human pancreatic cancers implanted subcutaneously into the dorsa of immunodeficient (SCID) mice. Treated tumors were examined histologically for microvessel density, apoptosis, and proliferation. All three inhibitors suppressed the growth of pancreatic tumors in vivo. Immunohistochemical analysis revealed increased degrees of apoptosis and reduced microvessel density in treated tumors compared to untreated tumors, although tumor cell proliferation was the same in both groups. None of the inhibitors tested significantly inhibited proliferation of human pancreatic cancer cells, although both TNP-470 and aaATIII were able to inhibit the proliferation of endothelial cells. The observed tumor suppression may be due to increased tumor cell apoptosis as a result of capillary dropout. These studies show that after the angiogenic switch in a human tumor, there is residual production of angiogenesis inhibitors.

Vitamin D binding protein-macrophage activating factor (DBP-maf) inhibits angiogenesis and tumor growth in mice.

We have isolated a selectively deglycosylated form of vitamin D binding protein (DBP-maf) generated from systemically available DBP by a human pancreatic cancer cell line. DBP-maf is antiproliferative for endothelial cells and antiangiogenic in the chorioallantoic membrane assay. DBP-maf administered daily was able to potently inhibit the growth of human pancreatic cancer in immune compromised mice (T/C=0.09). At higher doses, DBP-maf caused tumor regression. Histological examination revealed that treated tumors had a higher number of infiltrating macrophages as well as reduced microvessel density, and increased levels of apoptosis relative to untreated tumors. Taken together, these data suggest that DBP-maf is an antiangiogenic molecule that can act directly on endothelium as well as stimulate macrophages to attack both the endothelial and tumor cell compartment of a growing malignancy.

Adenovirus-mediated delivery of a soluble form of the VEGF receptor Flk1 delays the growth of murine and human pancreatic adenocarcinoma in mice.

BACKGROUND: Because pancreatic adenocarcinoma is poorly responsive to chemotherapy and radiation therapy, novel treatments such as antiangiogenic gene therapy may have use in the adjuvant treatment of this malignancy. We evaluated the antitumor effects of the in vivo administration of an adenovirus vector encoding a soluble form of Flk1 (Flk1-Fc), a receptor for vascular endothelial growth factor, in 3 murine models of pancreatic adenocarcinoma. METHODS: In a first model, immunocompetent C57Bl/6 mice were injected subcutaneously with Panc02 murine pancreatic adenocarcinoma cells before treatment. In a second model, immunodeficient severe combined immunodeficiency mice were injected subcutaneously with BxPc-3 human pancreatic adenocarcinoma cells before treatment. In a third model, C57Bl/6 mice were injected with Panc02 cells through an intrasplenic route before treatment, in an effort to model metastatic disease. In each model, half the tumor-bearing mice were injected intravenously with 10(9) Flk1-Fc adenovirus particles and half with control adenovirus. RESULTS: In subcutaneous tumor models, Ad Flk1-Fc-treated animals were found to have 75% smaller murine and 78% smaller human pancreatic tumor volumes, relative to tumor volumes of Ad Fc-treated animals, 6 weeks after vector administration. In animals injected with tumor through the intrasplenic route, pathologic and histologic analyses made 10 days after injection of tumor revealed hepatic, pancreatic, and splenic tumors, together with a desmoplastic response consistent with pathologic findings in human pancreatic cancer. Cohorts of these tumor-bearing mice treated with Ad Flk1-Fc demonstrated significantly longer survival and decreased liver replacement with tumor at the time of death, relative to animals treated with Ad Fc. CONCLUSION: A recombinant adenovirus encoding soluble Flk-1 inhibited pancreatic tumor growth in mice. These studies suggest that the delivery of gene products such as Flk1-Fc through in vivo gene transfer may be useful in the future treatment of patients with pancreatic cancer.

Pancreatic tumor growth is regulated by the balance between positive and negative modulators of angiogenesis.

There is increasing evidence for the implication of tumor-derived angiogenic and anti-angiogenic factors in controlling tumor growth in vivo. In this study, we documented the production of inhibitors of angiogenesis by pancreatic cancer cells and examined how changes in the balance between pro- and anti-angiogenic factors regulate tumor growth in vivo. The human pancreatic cancer cell line Hs-776T (HS-W) produces slow-growing tumors in SCID mice. Cells of a variant form (HS-R) of Hs-776T produced faster-growing tumors compared to HS-W. Characterization of HS-W and HS-R cells in vitro showed similar proliferation rates and production of the angiogenic factors vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF). Analyzes of anti-angiogenic factors showed comparable levels of angiostatin and thrombospondin 1 and 2, but endostatin was only detected in conditioned media of HS-W cells and was absent in HS-R. Cell proliferation was similar in both tumor types in vivo, whereas HS-W tumors demonstrated increased apoptosis with a high percentage of apoptotic endothelial cells (EC). Subsequently, VEGF was over-expressed in Hs-776T cells (HS-VF), resulting in rapidly growing tumors and lowering tumor and EC apoptosis. Collectively, our study confirms that tumor growth is dependent on its ability to increase the angiogenic stimulus or to reduce the amounts of endogenous anti-angiogenic factors.