Predictive value of hypoxia, proliferation and tyrosine kinase receptors for EGFR-inhibition and radiotherapy sensitivity in head and neck cancer models

Abstract

Background and Purpose EGFR-inhibitor Cetuximab (C225) improves the efficacy of radiotherapy in only a subgroup of HNSCC patients. Identification of predictive tumor characteristics is essential to improve patient selection. Material and Methods Response to C225 and/or radiotherapy was assessed with tumor growth delay assays in 4 HNSCC xenograft models with varying EGFR-expression levels. Hypoxia and proliferation was quantified with immunohistochemistry and expression of proteins involved in C225-resistance with western blot. Results EGFR-expression did not predict response to C225 and/or radiotherapy. Reduction of hypoxia by C225 was only observed in SCCNij202, which was highly sensitive to C225. Proliferation changes correlated with response to C225 and C225 combined with radiotherapy, as proliferation decreased after C225 treatment in C225-sensitive SCCNij202 and after combined treatment in SCCNij185, which showed a synergistic effect to combined C225-radiotherapy. Furthermore, C225-resistant SCCNij153 tumors expressed high levels of (activated) HER3 and MET. Conclusions EGFR-expression is needed for C225-response, but is not sufficient to predict response to C225 with or without radiotherapy. However, basal expression of additional growth factor receptors and effects on proliferation, but not hypoxia, correlated with response to combined C225-radiotherapy treatment and are potential clinically relevant predictive biomarkers.

111In-Cetuximab-F(ab′)2 SPECT and 18F-FDG PET for Prediction and Response Monitoring of Combined-Modality Treatment of Human Head and Neck Carcinomas in a Mouse Model

“…In several studies, the persistent activation of the mitogen-activated protein kinase (MAPK) or P13-K/AKT pathway has been shown to play an important role in EGFR inhibitor resistance (25,29,30). SCCNij185 is known to express high endogenous levels of phosphorylated AKT, which might explain the insensitivity toward cetuximab treatment in this model (21).…”

“…emphasizes the addiction to, and dependency on, EGFR ligands for continued proliferation and survival (21,22). A significant increase in 111 In-cetuximab-F(ab9) 2 uptake in the tumor 2.5 wk after treatment was seen in tumors resistant to therapy.…”

Imaging Integrin αvβ3 on Blood Vessels with 111In-RGD2 in Head and Neck Tumor Xenografts

“…Cells were maintained at 37°C in a humidified 5% CO 2 atmosphere and routinely passaged using a 0.25% trypsin/ethylenediaminetetraacetic acid solution (Invitrogen). Patient-derived SSCNij202 and SSCNij3 head and neck SCC (HNSCC) xenografts were maintained in female BALB/c nu/nu mice (21,22). In the right flank of 6-to 8-wkold female nude BALB/c nu/nu mice (Janvier), 5 · 10 6 FaDu cells in 200 mL of medium were injected subcutaneously, or a 1 mm 3 viable piece of SCCNij202 or SCCNij3 tumor xenografts was transplanted under anesthesia.…”

“…In micro-SPECT imaging studies, mice with FaDu, SCCNij3, or SCCNij202 tumor xenografts were injected intravenously with 1 mg of 111 In-RGD 2 (14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25). A 50-fold cold excess of RGD 2 was coinjected to investigate receptor-mediated localization of the radiolabeled peptide.…”

Early Response Monitoring with 18F-FDG PET and Cetuximab-F(ab′)2-SPECT After Radiotherapy of Human Head and Neck Squamous Cell Carcinomas in a Mouse Model

“…Several intrinsic prognostic markers have been identified as predictive markers in response to EGFR inhibition, including human papillomavirus (6,7), EGFR protein expression (8,9), and EGFR copy number (10,11), though research focuses on colorectal cancer and non-small cell lung cancer predominantly (12,13). In HNSCC, EGFRvIII, hypoxia, proliferation, and tyrosine kinase receptors have been studied as potential predictive markers for response to radiotherapy; however, no definite marker for response to EGFR-directed therapy has been found (14,15). Furthermore, early response markers are of interest to predict treatment efficacy of EGFR inhibitors, allowing for further personalized treatment.…”