There is a clinical need for noninvasive biomarkers of tumor hypoxia for prognostic and predictive studies, radiotherapy planning, and therapy monitoring. Oxygen-enhanced MRI (OE-MRI) is an emerging imaging technique for quantifying the spatial distribution and extent of tumor oxygen delivery in vivo. In OE-MRI, the longitudinal relaxation rate of protons (DR 1 ) changes in proportion to the concentration of molecular oxygen dissolved in plasma or interstitial tissue fluid. Therefore, well-oxygenated tissues show positive DR 1 . We hypothesized that the fraction of tumor tissue refractory to oxygen challenge (lack of positive DR 1 , termed "Oxy-R fraction") would be a robust biomarker of hypoxia in models with varying vascular and hypoxic features. Here, we demonstrate that OE-MRI signals are accurate, precise, and sensitive to changes in tumor pO 2 in highly vascular 786-0 renal cancer xenografts. Furthermore, we show that Oxy-R fraction can quantify the hypoxic fraction in multiple models with differing hypoxic and vascular phenotypes, when used in combination with measurements of tumor perfusion. Finally, Oxy-R fraction can detect dynamic changes in hypoxia induced by the vasomodulator agent hydralazine. In contrast, more conventional biomarkers of hypoxia (derived from blood oxygenation-level dependent MRI and dynamic contrast-enhanced MRI) did not relate to tumor hypoxia consistently. Our results show that the Oxy-R fraction accurately quantifies tumor hypoxia noninvasively and is immediately translatable to the clinic.
A panel of compounds belonging to the underexposed sulfamate class of carbonic anhydrase (CA, EC 4.2.1.1) inhibitors was generated that displayed high specificity at nanomolar levels for the tumor-associated CA IX/XII isoforms. Three of the specific CA IX/XII inhibitors showed a positive response in in vitro assays for tumor cell migration and spreading. One of them, 4-(3'-(3″,5″-dimethylphenyl)ureido)phenyl sulfamate (S4), was taken forward into the orthotopic MDA-MB-231 (breast carcinoma) model in mice. Treatment with a 10 mg/kg maintenance dosage of S4 given daily on a "5 days on, 2 days off" regimen reduced metastatic tumor burden in the lung while not affecting primary tumor growth or mouse condition. CA inhibitors of the sulfamate class specifically targeting the tumor-associated isoforms are potential candidates in antimetastatic therapy.
Purpose: Hypoxia is associated with poor prognosis and is predictive of poor response to cancer treatments, including radiotherapy. Developing noninvasive biomarkers that both detect hypoxia prior to treatment and track change in tumor hypoxia following treatment is required urgently. Experimental Design: We evaluated the ability of oxygenenhanced MRI (OE-MRI) to map and quantify therapyinduced changes in tumor hypoxia by measuring oxygenrefractory signals in perfused tissue (perfused Oxy-R). Clinical first-inhuman study in patients with non-small cell lung cancer (NSCLC) was performed alongside preclinical experiments in two xenograft tumors (Calu6 NSCLC model and U87 glioma model). Results: MRI perfused Oxy-R tumor fraction measurement of hypoxia was validated with ex vivo tissue pathology in both xenograft models. Calu6 and U87 experiments showed that MRI perfused Oxy-R tumor volume was reduced relative to control following single fraction 10-Gy radiation and fractionated chemoradiotherapy (P < 0.001) due to both improved perfusion and reduced oxygen consumption rate. Next, evaluation of 23 patients with NSCLC showed that OE-MRI was clinically feasible and that tumor perfused Oxy-R volume is repeatable [interclass correlation coefficient: 0.961 (95% CI, 0.858-0.990); coefficient of variation: 25.880%]. Group-wise perfused Oxy-R volume was reduced at 14 days following start of radiotherapy (P ¼ 0.015). OE-MRI detected between-subject variation in hypoxia modification in both xenograft and patient tumors. Conclusions: These findings support applying OE-MRI biomarkers to monitor hypoxia modification, to stratify patients in clinical trials of hypoxia-modifying therapies, to identify patients with hypoxic tumors that may fail treatment with immunotherapy, and to guide adaptive radiotherapy by mapping regional hypoxia.
Background: Heparan sulfate (HS) is an essential regulator of multiple angiogenic growth factors. Results: Down-regulation of 6-O-sulfation in endothelial cell HS affects FGF2-and VEGF-mediated endothelial cell functions.
Conclusion:The level of 6-O-sulfation in specific HS domains regulates endothelial cell responses to angiogenic growth factors. Significance: The relationships between 6-O-sulfation and endothelial phenotypes could help to design HS sequences inhibiting angiogenic growth factors.
PI3K plays a prominent role in the metastatic behavior of thyroid carcinoma cells irrespective of O(2) tension and appears upstream of HIF activation. GDC-0941 significantly inhibited the metastatic phenotype, supporting the clinical development of PI3K inhibition in thyroid carcinomas.
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