title: Radiosensitization and stromal imaging response correlates for the HIF-1 inhibitor PX-478 given with or without chemotherapy in pancreatic cancer.
abstract: Growing tumors are hypoxic and respond to microenvironmental stress through increased expression of the hypoxia inducible factor-1alpha (HIF-1alpha) transcription factor, resulting in an adaptive switch to glycolytic metabolism, angiogenic signaling, survival, and metastasis. HIF-1alpha expression is associated with tumor resistance to cytotoxic therapy and inferior patient outcomes. Pancreatic cancer is the most hypoxic of all solid tumors and remains refractory to current chemoradiotherapy. We have seen nuclear HIF-1alpha in 88% of human pancreatic ductal carcinoma but in only 16% of normal pancreas. Stroma adjacent to the pancreatic ductal carcinoma also showed HIF-1alpha in 43% of cases. We investigated the novel selective HIF-1alpha inhibitor PX-478 on in vitro and in vivo radiation response of human pancreatic cancer models. Inhibition of HIF-1alpha by PX-478 increased cell killing by radiation. In mice with Panc-1, CF-PAC-1, or SU.86.86 pancreatic xenografts, concurrent administration of PX-478 potentiated the antitumor effects of fractionated radiation, with or without combined treatment with 5-fluorouracil or gemcitabine. Alternative sequencing of PX-478 with fractionated radiotherapy suggests optimal radiosensitization with concurrent or neoadjuvant administration of drug. Early tumor responses to combined PX-478/radiation treatment could be rapidly and repeatedly quantified by vascular imaging biomarkers. Dual-tracer dynamic contrast enhanced-magnetic resonance imaging and ultrasound imaging discriminated response to combined treatment prior to detection of differences in anatomic tumor size at 10 days posttreatment. Therefore, PX-478 is a mechanistically appealing and potentially clinically relevant enhancer of pancreatic cancer radiosensitivity, inhibiting tumor and stromal HIF-1 proangiogenic signaling and reducing the innate radiation resistance of hypoxic tumor cells.
authors.affiliation: Department of Radiation Oncology, M.D. Anderson Cancer Center, Houston, Texas 77030, USA.
authors.forename: David L
authors.initials: DL
authors.lastname: Schwartz
authors.forename: James A
authors.initials: JA
authors.lastname: Bankson
authors.forename: Robert
authors.initials: R
authors.lastname: Lemos
authors.forename: Stephen Y
authors.initials: SY
authors.lastname: Lai
authors.forename: Arun K
authors.initials: AK
authors.lastname: Thittai
authors.forename: Yi
authors.initials: Y
authors.lastname: He
authors.forename: Galen
authors.initials: G
authors.lastname: Hostetter
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Demeure
authors.forename: Daniel D
authors.initials: DD
authors.lastname: Von Hoff
authors.forename: Garth
authors.initials: G
authors.lastname: Powis
mesh_terms: D000818:Animals; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use; D015153:Blotting, Western; D015687:Cell Hypoxia; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects / Q000528:radiation effects; D003131:Combined Modality Therapy; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D007150:Immunohistochemistry; D008279:Magnetic Resonance Imaging; D051379:Mice; D016513:Mice, SCID; D009150:Mustard Compounds / Q000008:administration & dosage / Q000494:pharmacology*; D010190:Pancreatic Neoplasms / Q000378:metabolism / Q000473:pathology / Q000628:therapy*; D010666:Phenylpropionates / Q000008:administration & dosage / Q000494:pharmacology*; D011878:Radiotherapy / Q000379:methods; D046888:Tissue Array Analysis; D047368:Tumor Burden / Q000187:drug effects / Q000528:radiation effects; D023041:Xenograft Model Antitumor Assays
chemical_list: C492908:2-amino-3-(4'-N,N-bis(2-chloroethyl)amino)phenylpropionic acid N-oxide; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D009150:Mustard Compounds; D010666:Phenylpropionates