Noninvasive monitoring of therapy-induced microvascular changes in a pancreatic cancer model using dynamic contrast-enhanced magnetic resonance imaging with P846, a new low-diffusible gadolinium-based contrast agent.

A predictive technique in the management of patients with cancer could improve the therapeutic index by allowing better individualization of treatment. Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) is a noninvasive technique that can provide anatomical and physiological information on the tumor and its microenvironment. We studied the effect of chemotherapy (gemcitabine), anti-angiogenesis therapy (sunitinib) and radiotherapy on the kinetics of DCE-MRI parameters in a preclinical model of pancreatic cancer using P846, a new low-diffusible contrast agent. Mice underwent DCE-MRI before treatment (MRI1), after 1 week of treatment (MRI2), and after 1 additional week (MRI3). Combined treatment with radiotherapy and sunitinib had a synergistic effect on tumor growth. In radiotherapy/sunitinib-treated mice, a decrease in K(trans) at MRI2 predicted its superior antivascular and antitumor effect at an early time. An increased K(trans) at MRI2, as seen in gemcitabine- and gemcitabine/sunitinib-treated mice, reflects increased permeability for P846 and might predict a smaller therapeutic effect at this early time. This study shows that the kinetics of DCE-MRI parameters depends on the contrast agent used. P846 appears to be a promising low-diffusible agent to monitor therapeutic effects in this preclinical cancer model, but further studies are needed to compare its behavior with Gd-DTPA and macromolecular-weight contrast agents. Sunitinib as a radiosensitizer is promising for future clinical trials in human pancreatic cancer.

Antiangiogenic versus cytotoxic therapeutic approaches in a mouse model of pancreatic cancer: an experimental study with a multitarget tyrosine kinase inhibitor (sunitinib), gemcitabine and radiotherapy.

This work evaluated SU11248 (sunitinib) as a potential therapeutic agent, alone or in combination with the cytotoxic agent gemcitabine or radiotherapy in a murine model of pancreatic cancer. Panc02 cells were injected subcutaneously into HsdOla/MF1 mice (n=222). Treatment was administered during 1 week: sunitinib (SUN), gemcitabine (GEM), radiotherapy (RT), RT+SUN and GEM+SUN. Mice were sacrificed 14 days after treatment. The effect on microvessel density (MVD) was measured by CD31 staining. Apoptosis (sFAS, cleaved caspase-3) and proangiogenic proteins (VEGF, PlGF, EGF) were measured with ELISA and immunohistochemistry. At day 14, tumors in all groups increased significantly despite treatment. Only after RT/SUN treatment tumor growth slowed down, although the accretion was still significant (P=0.033). Highest levels of apoptosis were seen in GEM/SUN, RT/SUN and RT treated mice (respectively P<0.001, P<0.01 and P<0.05 compared to placebo). MVD was lowest in RT/SUN treated mice [compared to placebo (P<0.05), GEM (P<0.05) and GEM/SUN (P<0.01)]. Highest VEGF levels were seen after RT and RT/SUN treatment [vs. placebo (P<0.001) and vs. other treatments (P<0.01 for all comparisons)]. GEM and SUN in monotherapy lead to an up-regulation of PlGF and EGF, respectively. In conclusion, the combination treatments RT/SUN and GEM/SUN result in a more potent anti-angiogenic and antitumor effect when compared to either treatment alone. Multitargeted angiogenesis inhibitor therapy with sunitinib combined with either radiotherapy or gemcitabine may be a novel approach for human pancreatic cancer.

Expression of SGLT1, Bcl-2 and p53 in primary pancreatic cancer related to survival.

Increased expression of glucose transporters has been reported in many cancers. It is not known whether Sodium dependent GLucose Transporter 1 (SGLT1) is up-regulated in pancreatic cancer. We studied the expression of SGLT1, Bcl-2 and p53 in primary pancreatic adenocarcinomas related to survival. In primary tumors, mean SGLT1-Hscore (n = 83) was 4.24 (median 3.0, range 0.5-15.0). Patients with positive staining for Bcl-2 had higher mean SGLT1-Hscores than those without Bcl-2 expression: 5.87 vs. 3.07 (P = 0.025). No correlation was found between expression of p53 and SGLT1 (P = 0.881). On multivariate analysis TNM stage (P = 0.015) and SGLT1 (P = 0.030) showed prognostic value for disease free survival (DFS). For overall survival (OS), TNM stage (P<0.001) and chemotherapy (P = 0.048) were prognostic and SGLT1 showed a trend (P = 0.071). In a subgroup of younger patients (age < or = median, 63.9 y) who did not receive chemotherapy, SGLT1 was a very strong predictor of DFS (P = 0.005). We conclude that high SGLT1 expression (H score > median, 3.0) in pancreatic adenocarcinomas was significantly correlated with DFS and a trend was found for OS, especially in younger patients. High SGLT1 expression in primary tumors was correlated with high Bcl-2 expression, not with p53 expression. This supports our hypothesis that SGLT1 and Bcl-2 expression could serve as prognostic markers in pancreatic cancer.