ESTRO 36 Abstract Book

S528 ESTRO 36 2017 _______________________________________________________________________________________________

Material and Methods 19 consecutive surgically resected HNSCCs were studied. WDF were collected 1 day and 3 days after surgery from the cancer operative bed. EGF, VEGF, SDF-1 and osteopontin levels were measured in WDF using enzyme- linked immunosorbent assay (ELISA) kits. Clonogenic assays were performed using Cal27 HNSCC cells irradiated with 1 to 6 Gy in presence or not of WDF and pretreated or not with cetuximab 6 hours before irradiation. Results The correlations between molecular levels and pathological cancer features showed that CXCL-12 expression was significantly increased in WDF in presence of lymph node metastasis (p<0,05), lymph node density (p<0,05) and extra capsular spread (ECS) (P<0,05). Osteopontin expression was significantly increased in presence of ECS (p<0,05). TGF-β expression was significantly reduced in presence of ECS (P<0,0000001) and for patients treated for a cancer relapse (p<0,001). Clonogenic assays evidenced that WDF reduced efficacy of irradiation on Cal27 cells with an increase of clonogenic survival compared to control (that is irradiated cells without WDF). Pretreatment of cells with cetuximab reduced surviving fraction to values comparable to control. Conclusion Preliminary data from pilot study evidenced that microenvironment in WDF favors residual tumor cell proliferation and affects response to radiation. Early treatment with biological therapies can increase radio sensitivity and improve outcome. PO-0965 Imaging of the hypoxia related marker Carbonic Anhydrase IX in human head and neck cancer xenografts F.J. Huizing 1 , B.A.W. Hoeben 1 , O.C. Boerman 2 , J. Bussink 1 1 Radboudumc, Radiation oncology, Nijmegen, The Netherlands 2 Radboudumc, Nuclear medicine, Nijmegen, The Netherlands Purpose or Objective Tumor hypoxia forms a major factor in radio- and chemoresistance in head and neck cancer and other solid tumors. Assessment of tumor hypoxia may allow patient selection for hypoxia or CAIX targeting treatment combined with radiotherapy. Recently, the radioactive tracer 111 In-girentuximab-F(ab’) 2 was designed to target the endogenous hypoxia related marker carbonic anhydrase IX (CAIX), in combination with a SPECT scan this tracer can be used for imaging. The purpose of this study was to characterize 111 In-girentuximab-F(ab’) 2 in a preclinical setting. Material and Methods First the affinity and internalization kinetics of 111 In- girentuximab-F(ab’) 2 were determined in vitro with the use of SK-RC-52 cells. The optimal timing and optimal protein dose for imaging were determined in athymic nude mice with a subcutaneous xenografted human head and neck carcinoma. Tracer uptake was measured using the U- SPECT, by analyzing ex vivo activity counting and by autoradiography of tumor sections. Immunohistochemical staining was used to validate the tracer uptake to the CAIX expression. Results In vitro 26% of the tracs internalized into the SK-RC-52 cells after 24 hours. The half maximal inhibitory concentration was 0.69 ± 0.08 nM. As optimal time between tracer injection and imaging we found 24 hours to be optimal. The protein dose of 10 microgram will result in the highest tumor to blood ratio after 24 hours. Immunohistochemical images show a distinct spatial correlation to autoradiography images (Fig. 1).

was observed between the 95% confidence ellipses for the three positions in the SOBP (see Fig 1). An RBE increase up to 1.46 was determined for the distal fall-off position (see Fig 2).

Conclusion The results obtained in the current study with V-79 fibroblast cells confirm the expected increase in RBE along the proton Bragg curve.

Poster: Radiobiology track: Radiobiology of head and neck cancer

PO-0964 Biomarkers in wound drainage fluids affect response to radiations of head and neck cancer cells M. Mangoni 1 , M. Sottili 1 , T. Gualtieri 2 , A. Javarone 2 , M. Loi 1 , I. Meattini 1 , P. Bonomo 1 , I. Desideri 1 , A. Deganello 2 , L. Livi 1 1 University of Florence, Experimental and Clinical Biomedical Sciences, Firenze, Italy 2 University of Florence, Academic Clinic of Otorynolaryngology and Head and Neck Surgery, Firenze, Italy Purpose or Objective In recent years in head and neck oncology many efforts have been made in order to characterize molecular biomarkers with potential prognostic and therapeutic value. The detection of significant features in the early perioperative setting could possibly lead to a refinement of current adjuvant treatments in high-risk patients. The purpose of our study is to report the feasibility and preliminary results of a pilot prospective study on wound drainage fluids (WDF) analysis in head and neck squamous cells carcinoma (HNSCC) and to evaluate effect of WDF microenvironment on HNSCC response to radiation.