Strategic plans to promote head and neck cancer translational research within the radiation therapy oncology group: a report from the translational research program

Recent advances in radiation oncology

Radiotherapy (RT) is very much a technology-driven treatment modality in the management of cancer. RT techniques have changed significantly over the past few decades, thanks to improvements in engineering and computing. We aim to highlight the recent developments in radiation oncology, focusing on the technological and biological advances. We will present state-of-the-art treatment techniques, employing photon beams, such as intensity-modulated RT, volumetric-modulated arc therapy, stereotactic body RT and adaptive RT, which make possible a highly tailored dose distribution with maximum normal tissue sparing. We will analyse all the steps involved in the treatment: imaging, delineation of the tumour and organs at risk, treatment planning and finally image-guidance for accurate tumour localisation before and during treatment delivery. Particular attention will be given to the crucial role that imaging plays throughout the entire process. In the case of adaptive RT, the precise identification of target volumes as well as the monitoring of tumour response/modification during the course of treatment is mainly based on multimodality imaging that integrates morphological, functional and metabolic information. Moreover, real-time imaging of the tumour is essential in breathing adaptive techniques to compensate for tumour motion due to respiration. Brief reference will be made to the recent spread of particle beam therapy, in particular to the use of protons, but also to the yet limited experience of using heavy particles such as carbon ions. Finally, we will analyse the latest biological advances in tumour targeting. Indeed, the effectiveness of RT has been improved not only by technological developments but also through the integration of radiobiological knowledge to produce more efficient and personalised treatment strategies.

Porous silicon for cancer therapy: from fundamental research to the clinic

Porous silicon (PSi) has emerged over the past decade as a promising biomaterial for nanomedicine in general and cancer nanomedicine in particular. PSi offers a unique combination of properties, including large surface area and porous volume, biocompatibility, degradability

The role of imaging in radiation therapy planning: past, present, and future

The use of ionizing radiation for cancer treatment has undergone extraordinary development during the past hundred years. The advancement of medical imaging has been critical in helping to achieve this change. The invention of computed tomography (CT) was pivotal in the development of treatment planning. Despite some disadvantages, CT remains the only three-dimensional imaging modality used for dose calculation. Newer image modalities, such as magnetic resonance (MR) imaging and positron emission tomography (PET), are also used secondarily in the treatment-planning process. MR, with its better tissue contrast and resolution than those of CT, improves tumor definition compared with CT planning alone. PET also provides metabolic information to supplement the CT and MR anatomical information. With emerging molecular imaging techniques, the ability to visualize and characterize tumors with regard to their metabolic profile, active pathways, and genetic markers, both across different tumors and within individual, heterogeneous tumors, will inform clinicians regarding the treatment options most likely to benefit a patient and to detect at the earliest time possible if and where a chosen therapy is working. In the post-human-genome era, multimodality scanners such as PET/CT and PET/MR will provide optimal tumor targeting information.

Targeting FAK radiosensitizes 3-dimensional grown human HNSCC cells through reduced Akt1 and MEK1/2 signaling

PURPOSE

Focal adhesion kinase (FAK), a main regulator of integrin signaling and cell migration, is frequently overexpressed and hyperphosphorylated in human head-and-neck squamous cell carcinoma (HNSCC). We have previously shown that pharmacologic FAK inhibition leads to radiosensitization of 3-dimensionally grown HNSCC cell lines. To further evaluate the role of FAK in radioresistance and as a potential cancer target, we examined FAK and FAK downstream signaling in HNSCC cell lines grown in more physiologic extracellular matrix-based 3-dimensional cell cultures.

METHODS AND MATERIALS

Seven HNSCC cell lines were grown in 3-dimensional extracellular matrix and the clonogenic radiation survival, expression, and phosphorylation of FAK, paxillin, Akt1, extracellular signal-regulated kinase (ERK)1/2, and MEK1/2 were analyzed after siRNA-mediated knockdown of FAK, Akt1, MEK1, FAK+Akt1, or FAK+MEK1 compared with controls or stable overexpression of FAK. The role of MEK1/2 for clonogenic survival and signaling was investigated using the MEK inhibitor U0126 with or without irradiation.

RESULTS

FAK knockdown moderately or significantly enhanced the cellular radiosensitivity of 3-dimensionally grown HNSCC cells. The FAK downstream targets paxillin, Akt1, and ERK1/2 were substantially dephosphorylated under FAK depletion. FAK overexpression, in contrast, increased radiation survival and paxillin, Akt1, and ERK1/2 phosphorylation. The degree of radiosensitization upon Akt1, ERK1/2, or MEK1 depletion or U0126 was superimposable to FAK knockdown. Combination knockdown conditions (ie, Akt1/FAK, MEK1/FAK, or U0126/FAK) failed to provide additional radiosensitization.

CONCLUSIONS

Our data provide further evidence for FAK as important determinant of radiation survival, which acts in the same signaling axis as Akt1 and ERK1/2. These data strongly support our hypothesis that FAK is a relevant molecular target for HNSCC radiotherapy.

Tissue biomarker development in a multicentre trial context: a feasibility study on the PETACC3 stage II and III colon cancer adjuvant treatment trial

PURPOSE

We evaluated the feasibility of biomarker development in the context of multicenter clinical trials.

EXPERIMENTAL DESIGN

Formalin-fixed, paraffin-embedded (FFPE) tissue samples were collected from a prospective adjuvant colon cancer trial (PETACC3). DNA was isolated from tumor as well as normal tissue and used for analysis of microsatellite instability, KRAS and BRAF genotyping, UGT1A1 genotyping, and loss of heterozygosity of 18 q loci. Immunohistochemistry was used to test expression of TERT, SMAD4, p53, and TYMS. Messenger RNA was retrieved and tested for use in expression profiling experiments.

RESULTS

Of the 3,278 patients entered in the study, FFPE blocks were obtained from 1,564 patients coming from 368 different centers in 31 countries. In over 95% of the samples, genomic DNA tests yielded a reliable result. Of the immmunohistochemical tests, p53 and SMAD4 staining did best with reliable results in over 85% of the cases. TERT was the most problematic test with 46% of failures, mostly due to insufficient tissue processing quality. Good quality mRNA was obtained, usable in expression profiling experiments.

CONCLUSIONS

Prospective clinical trials can be used as framework for biomarker development using routinely processed FFPE tissues. Our results support the notion that as a rule, translational studies based on FFPE should be included in prospective clinical trials.

Targeting EGFR resistance networks in head and neck cancer

A core set of oncoproteins is overexpressed or functionally activated in many types of cancer, and members of this group have attracted significant interest as subjects for development of targeted therapeutics. For some oncoproteins such as EGFR/ErbB1, both small molecule and antibody agents have been developed and applied in the clinic for over a decade. Analysis of clinical outcomes has revealed an initially unexpected complexity in the response of patients to these agents. Diverse factors, including developmental lineage of the tumor progenitor cell, co-mutation or epigenetic modulation of genes encoding proteins in an extended EGFR signaling network or regulating core survival responses in individual tumors, and environmental factors including inflammatory agents and viral infection, all have been identified as modulating response to treatment with EGFR-targeted drugs. Second and third generation therapeutic strategies increasingly incorporate knowledge of cancer type-specific signaling environments, in a more personalized treatment approach. This review takes squamous cell carcinoma of the head and neck (SCCHN) as a specific example of an EGFR-involved cancer with idiosyncratic biological features that influence design of treatment modalities, with particular emphasis on commonalities and differences with other cancer types.

Isoflavones and gamma irradiation inhibit cell growth in human salivary gland cells

We studied the effects of isoflavones and irradiation on cell cycle in a human salivary gland cell line (HSG). Genistein and a soy isoflavone conjugate (NS) inhibited DNA synthesis. Cells deconjugated the glucoside form of isoflavones in NS to the aglycones genistein and daidzein. NS, genistein and IR increased phosphorylation of p53 and p21 CIP1 at serine 15 (phos-p53). Irradiation and NS also increased levels of p21 CIP1. In a cologenic survival assay, cells in log phase growth had high radio-sensitivity with 2 Gy causing a reduction in survival (SF2=0.45).

CONCLUSION

isoflavones and radiation may interact to sensitize cancer cells to radiation.