Discovery of prognostic markers in laryngeal cancer treated with radiotherapy Bruine de Bruin, Leonie
DOI:
10.33612/diss.143832673
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Bruine de Bruin, L. (2020). Discovery of prognostic markers in laryngeal cancer treated with radiotherapy.
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cancer treated with radiotherapy
Leonie Bruine de Bruin
© L. Bruine de Bruin, 2020. Al rights reserved. No part of this thesis may be reproduced or transmitted without prior written permission of the author.
The publication of this thesis was financially supported by:
Prof. dr. Eelco Huizinga Stichting, Ziekenhuis St Jansdal, Intermedis A&A, ALK-Abelló BV, Graduate School of Medical Sciences, Soluvos Medical BV, Atos Medical BV.
laryngeal cancer treated with radiotherapy
Proefschrift
ter verkrijging van de graad van doctor aan de Rijksuniversiteit Groningen
op gezag van de rector magnificus prof. dr. C. Wijmenga en volgens besluit van het College voor Promoties.
De openbare verdediging zal plaatsvinden op dinsdag 24 november 2020 om 12:45 uur
door
Leonie Bruine de Bruin
geboren op 11 augustus 1984 te Amersfoort
Prof. dr. E. Schuuring
Copromotores Dr. G.B. Halmos Dr. B. van der Vegt
Beoordelingscommissie Prof. dr. S.M. Willems Prof. dr. F.K.L. Spijkervet Prof. dr. M.W.M. van den Brekel
Eline Bruine de Bruin
Chapter 1 General introduction 9
Chapter 2 Head and neck tumor hypoxia imaging by
18F-fluoroazomycin-arabinoside (18F-FAZA)-PET: a review Clinical Nuclear Medicine. 2014 Jan;39(1):44-48
27
Chapter 3 Assessment of hypoxic subvolumes in laryngeal cancer with
18F-fluoroazomycinarabinoside (18F-FAZA)-PET/CT scanning and immunohistochemistry
Radiotherapy & Oncology. 2015 Oct;117(1):106-112
43
Chapter 4 PTEN is associated with worse local control in early stage supraglottic laryngeal cancer treated with radiotherapy Laryngoscope Investigative Otolaryngology. 2019 Jun 12;4(4):399-404
59
Chapter 5 High pATM is associated with poor local control in supraglottic cancer treated with radiotherapy Laryngoscope. 2020 Aug;130(8):1954-1960
75
Chapter 6 High DNMT1 expression is associated with worse local control in early stage laryngeal squamous cell carcinoma Submitted
95
Chapter 7 Summary and general discussion 109
Nederlandse samenvatting 131
List of publications 137
Dankwoord 139
Curriculum vitae 143
Chapter 1
General introduction
GENERAL INTRODUCTION 1
Head and neck cancer
Head and neck cancer is the eight most common cancer in the world with an estimated incidence of 890,000 cases per year in 20171. It commonly refers to a collection of cancers, predominantly squamous cell carcinomas (HNSCC) arising from the epithelial lining of the oral cavity, pharynx and larynx. This thesis focuses on HNSCC and in particular laryngeal squamous cell carcinomas (LSCC).
Laryngeal squamous cell carcinoma
Of all HNSCC, 25% originate in de larynx. In recent years, around 700 cases of LSCC were diagnosed annually in the Netherlands2. Smoking and alcohol consumption are the major risk factors for developing LSCC. Unlike in oropharynx carcinoma, in LSCC high-risk HPV16 or HPV18 infections are rarely seen as a risk factor. Low-risk HPV6 and HPV11 are strongly associated with recurrent respiratory papillomatosis in the larynx but not detected in LSCC3.
Treatment options of LSCC consist of surgery (endoscopic or external approach), radiotherapy, and a combination of these treatments or chemoradiation4. Based on national and international guidelines, in our institute early stage LSCC patients are treated with radiotherapy as single modality treatment with the exception of T1a glottic LSCC in which transoral CO2 laser microscopic surgery can be an alternative with equivalent results compared to radiotherapy5-7. Although a meta-analysis revealed that there was insufficient evidence to establish a clear superiority for laser surgery versus radiotherapy for T1-T2N0 glottic cancer8, laser surgery has the advantage of keeping all treatment modalities available for the treatment of possible recurrences. In other cases of early stage (T1-T2) LSCC, hyperfractionated or accelerated radiotherapy is the treatment of choice to preserve laryngeal function (voice, swallowing and breathing). Locally advanced (T3-T4) disease is treated with radiotherapy or combined chemoradiation, unless no functional larynx is present or can be expected after treatment. In these cases, total laryngectomy needs to be considered. In case chemoradiation is not feasible for patients with locally advanced non-metastatic LSCC, the use of EGFR-targeted therapy (e.g. cetuximab) is approved by the U.S. Food and Drug Administration (FDA) and European Medicines Agency (EMA) in combination with radiotherapy based on studies by Bonner et al.9-11. However, specifically in laryngeal cancer adding cetuximab to the radiation therapy does not seem to improve survival12. Patients with a
positive lymph node status (N+) require definitive treatment of the neck, either by comprehensive neck dissection or by definitive (chemo)radiation. For supraglottic LSCC, elective bilateral treatment of the neck should be undertaken for T2 or higher stages. However, for patients with glottic disease sole treatment of the primary site is sufficient and elective unilateral treatment of the neck is not needed until tumors are stages T3 or greater4.
Radiotherapy for the treatment of laryngeal cancer
Radiotherapy plays an important role in the treatment of LSCC patients. Efficacy of radiotherapy relies on DNA damage, either via direct damage of DNA by ionizing radiation or by free radicals that are generated and subsequently react with DNA, which is the more common mechanism of DNA damage. This leads to single and double strand DNA breaks, which ultimately result in apoptosis13. An increasing radiotherapy dose will lead to increasing cell death of neoplastic cells. However, normal cells will also be damaged which leads to toxic side effects like dermatitis, mucositis, pain, dysphagia and xerostomia. To prevent these side effects, patients are treated with fractionated radiotherapy to enable normal tissues to recover and repopulate. However, recovery and repopulation does not only occur in normal tissue, but also in neoplastic cells. To reduce repopulation of neoplastic cells, accelerated radiotherapy is given with a daily dose of 2 Gy for six fractions per week for a total of 66-70 Gy in total.
The local control rate for T1-T2 laryngeal carcinoma obtained with primary radiotherapy is 70-95%14-16. In case of local recurrence, frequently a disabling total laryngectomy is required as a salvage surgery. Moreover, complications and morbidity are considerably high in patients who undergo a salvage laryngectomy after radiotherapy with/without chemotherapy17.
Prognostic tumor-specific biomarkers for LSCC treated with radiotherapy Recurrences in early-stage (T1-T2) LSCC treated with radiotherapy will result in a disabling total laryngectomy. Given the high recurrence rate, prognostic factors for the development of a local recurrence after primary radiotherapy are needed to select the most optimal treatment for individual patients. Besides TNM classification, anterior commissure involvement, sublocation in which supraglottic cancers have worse prognosis than glottic cancers and a number of clinical factors, like smoking and alcohol consumption habits, there is a lack of clinical prognostic factors to predict worse local control after radiotherapy in LSCC4,18,19.
In the past decades, research has concentrated on the identification of new
1
tumor specific biomarkers to predict clinical outcome. Especially markers involved in tumorigenesis and tumor progression, such as genes associated with processes like apoptosis, angiogenesis and cell growth, have been investigated extensively in relation with radioresponse in LSCC13,19,20.
Hypoxia as a prognostic factor
Among the several mechanisms proposed as potential causes of radioresistance, hypoxia has been studied the most21. Hypoxia is characteristic for many solid tumors, including head and neck cancer21-23. It was already proposed in the 1950s that the radiosensitivity of tumors is limited by hypoxia24. The biological effect of radiotherapy depends on the degree of tissue oxygenation and hypoxic cells are approximately threefold more resistant to radiation than well oxygenated cells25-28. Oxygen free radicals are highly reactive and are the primary source of radiation- induced DNA damage. Therefore, oxygen is a potent radiosensitizer. Indirectly, hypoxia-induced genomic changes may have impact on radiation resistance by altering proliferation, cell cycle, apoptosis, angiogenesis and anaerobic glycolysis29-31. In many tumor types, including head and neck cancer, hypoxia is associated with worse locoregional control22,23,27,31,32.
Patients with a hypoxic tumor might benefit from hypoxic modification during radiotherapy treatment. For example application of hypoxia sensitizers as nitroimidazoles to radiotherapy, radiotherapy with carbogen and nicotinamide (ARCON) or increased radiation dose to hypoxic areas or hyperbaric oxygen treatment have been investigated in HNSCC26,33-35.
However, assessing tumor hypoxia is a challenge. Direct measurement of tumor oxygenation is possible with (Eppendorf) polarographic needle electrodes31,36,37. Clinical studies demonstrated that this method could be used to predict tumor response and treatment outcome in patients with HNSCC treated with radiotherapy38. However, a later study by the same researchers disagreed with the conclusions in their first study39. This can partly be explained by the spatial heterogeneity of hypoxia in the tumor. An important disadvantage of using the needle electrodes is the restricted use to accessible tumors and intertumoral heterogeneity of hypoxia known for many years40.
Other, histological, methods to asses tumor hypoxia are the use of exogenous (2-nitroimidazole compounds such as pimonidazole) and endogenous (HIF1α, CA- IX, GLUT-1) hypoxia markers using immunohistochemistry28,31,41. The advantage is
that presence of hypoxia could be related to histological morphology. Exogenous markers are drugs, chemicals or even bacteria that, after administration to the patient, specifically accumulate or are bio-reducible under hypoxic conditions.
Binding is ascertained in tissue biopsies using specific antibodies. One of the clinically relevant markers is the 2-nitroimidazole pimonidazole42,43 that is injected intravenously before biopsy taken or surgery. It is reductively activated and forms protein products in mammalian cells at low pO2 level43. The prognostic significance of pimonidazole was demonstrated by Kaanders et al. who showed worse locoregional control in patients with high pimonidazole binding as compared to low pimonidazole binding in advanced head and neck cancer44. The disadvantage of exogenous markers is that the chemical solution must be administered intravenously to the patient before biopsy/surgery. Therefore, expression of exogenous hypoxia markers can only be investigated in tissue samples from patients who underwent this procedure preoperative and was performed only in few retrospective studies.
Under hypoxic conditions, hypoxia inducible factor 1-alpha (HIF1α) is upregulated, which leads to activation of transcription of many genes, including carbonic anhydrases and glucose transporters. These proteins are involved in many processes, such as angiogenesis, pH-regulation, cell proliferation, cell survival and apoptosis, erythropoiesis, and energy and glucose metabolism45,46. Increased expression of HIF1α detected by immunohistochemistry has been associated with poor locoregional control after radiotherapy in LSCC32,47,48. Carbonic anhydrase IX (CA-IX) catalyzes reversible hydration of carbon dioxide to carbonic acid thereby maintaining a stable intracellular pH in hypoxic conditions. High expression of CA-IX was found in many different tumor tissues. In vitro and in vivo studies demonstrated that CA-IX was strongly induced by hypoxia in a broad range of tumors. It was also shown that CA-IX positivity was associated with resistance to radiation32,49,50. In contrast, low expression of CA-IX was predictive for response to accelerated radiotherapy with carbogen breathing and nicotinamide (ARCON), a hypoxia target therapy, in laryngeal cancer51. Although CA-IX is a promising hypoxia marker, a weak correlation with pimonidazole44 questioned its value as a marker for hypoxia. However, we cannot exclude that pimonidazole is poorly associated with hypoxia and thus CA-IX is a good predictor because studies are lacking to correlate expression with hypoxic tumor areas. GLUT-1 appeared to be one of the prominent glucose transporters. Increased expression enables higher cellular uptake of glucose and facilitates anaerobic glycolysis52. GLUT-1 expression
in head and neck tumors is found at distance from vessels and adjacent to necrotic
1
areas, and indicates diffusion-limited hypoxia53. Furthermore, a correlation with oxygen electrode measurements and expression of pimonidazole and CA-IX was found54,55.
In summary, HIF1α, CA-IX and GLUT-1 are the most extensively studied endogenous markers of tumor hypoxia. These biomarkers were associated with worse survival and local control, almost regardless of the therapy provided.
Differences in outcome between various studies can be explained by spatial heterogeneity in the distribution of hypoxia, many ways to score biomarker expression levels and the use of different cutoff levels to define low/high expression reported in literature. In addition, expression of many hypoxia-related genes may be a complex function of hypoxia-dependent and -independent pathways 52. For instance, HIF1α, CA-IX and GLUT-1 accumulation can be observed also under other conditions than hypoxia, for example, hypoglycemia and acidosis56 suggesting these markers are not robust hypoxia markers but might reflect a more aggressive tumor phenotype57.
Hypoxia imaging
Alternative and non-invasive methods to obtain information about the oxygenation status with the possibility to use this for radiotherapy treatment planning (for escalating the dose to the hypoxic regions) include the use of radiologic and nuclear imaging techniques. During the past decades many PET tracers for detecting the proportion of hypoxic cells in vivo have been developed.
Most widely used are the 2-nitroimidazoles like 18F-labeled fluoromisonidazole (18F-FMISO) or 18F-fluoroazomycinarabinoside (18F-FAZA)-PET58. Several animal and human studies evaluated the use of radiolabeled nitroimidazoles for assessment of the oxygenation status in solid tumors59,60. Clinical studies performed on patients with head and neck cancer demonstrated the potential prognostic value of hypoxia imaging with 18F-FMISO for radiotherapy outcome61-64. In a small group of patients with HNSCC, pre-treatment tumor hypoxic fraction assessed using PET imaging of 18F-FAZA was predictive of survival following radiotherapy65. However, the ideal hypoxia PET tracer should express only relevant oxygen concentrations in viable cells and possess uniform and rapid cell entry (lipophilic molecule), rapid clearance from normoxic cells (hydrophilic molecule) and yielding a high target-to-background ratio. Overall, fluorinated nitroimidazoles have a low tumor uptake relative to surrounding tissue and 18F-FAZA has been shown to be superior
to 18F-FMISO66,67. None of the radiotracers that have been used in clinical studies fulfill all properties and development of better protocols in existing radiotracers and search in new tracers is still on-going. Furthermore, there is a lack of studies verifying hypoxia in hypoxic subvolumes seen on hypoxia PET imaging.
Prognostic value of EGFR and PTEN
The epidermal growth factor receptor (EGFR) is a transmembrane protein that is a receptor tyrosine kinase for extracellular ligands such as EGF. Ligand-binding to EGFR induces activation of the intrinsic kinase domain and stimulation of downstream signaling pathways such as the P13K/AKT pathway, regulating numerous cellular responses such as increased cell proliferation, decreased insensitivity to apoptosis, migration and differentiation13. Increased expression of EGFR is commonly observed in many human cancers including head and neck68-70. Furthermore, EGFR expression has been significantly correlated with poor local control after radio- or chemotherapy in different cancer types, including head and neck cancer71-74. Consequently, intensive research has focused on EGFR as potential target for cancer therapy. Although expression of EGFR is not a predictor for response to cetuximab, a monoclonal antibody targeting EGFR75, patients with HNSCC independent of EGFR status also significantly benefit from treatment with cetuximab10. Since 2006, the use of cetuximab is approved by the FDA and EMA in combination with radiotherapy for patients with locally advanced non-metastatic HNSCC in case chemoradiation is not feasible11.
Another mechanism for PI3K/AKT pathway activation is the loss of PTEN (phosphatase and tensin homolog deleted on chromosome 10), a tumor suppressor gene which opposes PI3K/AKT activation11,76,77. PTEN is the second most affected tumor suppressor gene after p53 and mutations/deletions in PTEN are found in a variety of primary tumors including HNSCC78-82. In a cohort of patients with locally advanced HNSCC postoperatively treated with radiotherapy, overexpression of PTEN was associated with increased radioresistance83, in line with an alternative role of PTEN in DNA damage repair82,84.
DNA damage response markers as biomarkers for radiation response
During radiotherapy, DNA double strand breaks (DSBs) are introduced to cause cell death. DSBs activate a complex DNA damage response (DDR) pathway that controls cell cycle checkpoints, DNA repair and apoptosis85. Central in the DDR is the protein kinase ataxia telangiectasia mutated protein (ATM)86-91. DNA DSB induced
by ionizing radiation leads to activation of ATM and subsequently phosphorylates
1
a variety of substrates including the checkpoint kinase 2 (Chk2) which is known to prevent entry into mitosis. Both phosphorylated ATM and Chk2 are known to activate the tumor suppressor gene p53 with cell cycle arrest and apoptosis86-90.
In patients with cervical cancer treated with (chemo)radiation, high levels of phosphorylated ATM were linked to poor locoregional disease-free survival and inhibition of ATM sensitizes cell lines to radiation92. Although inhibition of ATM was also demonstrated to sensitize HNSCC cell lines to radiation93,94, only few studies using tumor tissues from patients with head and neck cancer showed no relation between ATM expression and response to chemo(radiation)95,96.
Epigenetic changes as prognosticator in LSCC treated with radiotherapy
DNA methylation is one of the major forms of epigenetic regulation of gene expression. Among others, it plays an important role in tumorigenesis leading to the epigenetic modulation of the expression of tumor suppressor genes involved in cell cycle regulation, apoptosis, and DNA repair97-99. In cancer, DNA methylation becomes aberrant, causing global hypomethylation and local hypermethylation in tumor suppressor genes as compared to normal cells100. DNA methylation was found to be associated with clinical outcome in HNSCC in our research group101-103 and others104,105.
DNA methylation is regulated by the DNA methyltransferase (DNMT) enzymes such as DNMT1, DNMT3A and DNMT3B97. High expression of DNMT’s in a variety of tumors was associated with hypermethylation and oncogenic activation106. DNMT1 expression correlates well with aberrant DNA methylation in solid tumors, including esophageal carcinomas resulting in poor prognosis in patients107. DNMT1 expression positively correlated with radiation sensitization and longer survival of esophageal squamous cell carcinoma patients108. Furthermore, positive staining for DNMT1 was significantly linked to lower rates of treatment response and shorter survival of patients with pharyngeal squamous cell carcinoma treated with surgery combined with adjuvant radiotherapy with/without chemotherapy, or definitive concurrent chemoradiotherapy109. DNMT inhibitors were demonstrated to sensitize HNSCC cell lines to irradiation110. Epigenetic therapies, such as with DNMT1 inhibitors used in clinical practice (like azacitidine, decitabine, zebularine)111 leading to hypomethylation of DNA, might offer new opportunities for modulating the radiation resistance of tumors112.
OUTLINE OF THIS THESIS
In early stage (T1-T2) LSCC radiotherapy is the preferred choice of treatment because of laryngeal preservation. Despite the relatively high treatment response rate after radiotherapy a considerable number of patients will develop a local recurrence, which consequently requires salvage surgery (i.e. total laryngectomy) with high morbidity and deterioration of quality of life. For individual patients, it would be useful to predict local tumor control after radiotherapy on the pre-treatment biopsy. In HNSCC many studies have been performed to identify prognostic tumor biomarkers. However, diversity in staining protocols and in the composition of study populations makes it difficult to compare the reported results and determine the clinical value of these biomarkers as prognostic factors for local control.
In the first part of this thesis (Chapter 2 and 3), the feasibility of a hypoxia PET tracer is investigated. In the second part of this thesis (Chapter 4, 5 and 6), tumor biomarkers associated with local control are investigated in a well-defined homogeneous cohort of early stage (T1-T2) glottic and supraglottic LSCC patients all treated with curatively intended radiotherapy. For this purpose, we used a bio-database covering 1286 patients diagnosed with LSCC at the department of Otorhinolaryngology/ Head & Neck Surgery in the University Medical Center Groningen (UMCG) between 1990 and 2008. Clinicopathological baseline and follow-up data were available from the archives of the departments of Otorhinolaryngology/ Head & Neck Surgery, Pathology and Radiation Oncology.
Formalin-fixed and paraffin-embedded pre-treatment tissue biopsies with sufficient neoplastic cells were selected for immunohistochemical analysis.
Chapter 2 gives a comprehensive review on different animal and human
18F-FAZA-PET studies and its potential use for individualized treatment in patients with hypoxic head and neck tumors. In Chapter 3, the accuracy of 18F-FAZA-PET/CT scan in detecting hypoxic regions within the tumor using exogenous (pimonidazole) and endogenous (HIF1α, CA-IX and GLUT-1) immunohistochemical markers is investigated. For this purpose 11 patients were selected (outside previous mentioned database) with an indication for total laryngectomy because of locally advanced or recurrent laryngeal carcinoma. The prognostic value of EGFR and PTEN expression on local control in 52 patients from our database with early-stage supraglottic LSCC treated with radiotherapy, is evaluated in Chapter 4. The prognostic value of the immunohistochemical expression of pATM, pChk2 and p53, all involved in the ATM-associated DNA damage response pathway, is investigated in our
series of patients with early-stage LSCC treated with radiotherapy in Chapter 5.
1
Because DNA methylation is regulated by DNMT1, in Chapter 6 we investigate the association between DNMT1 expression and local control in LSCC patients treated with radiotherapy. Chapter 7 provides a summary, general discussion and some future perspectives. Chapter 8 provides a Dutch summary of the results.
REFERENCES
1. Global Burden of Disease Cancer Collaboration, Fitzmaurice C, Abate D, et al. Global, regional, and national cancer incidence, mortality, years of life lost, years lived with disability, and disability- adjusted life-years for 29 cancer groups, 1990 to 2017: A systematic analysis for the global burden of disease study. JAMA Oncol. 2019.
2. Statistics on cancer in the Netherlands based on data from the Netherlands Cancer Registry man- aged by the Netherlands Comprehensive Cancer Organization (IKNL). Retrieved July 15, 2020, from https://www.iknl.nl/nkr-cijfers?fs%7Cepidemiologie_id=6&fs%7Ctumor_id=200&fs%7Cregio_
id=155&fs%7Cperiode_id=78%2C79%2C80%2C81%2C82%2C83%2C84%2C85%2C86%2C87%2C88
%2C89%2C90%2C91%2C92%2C93%2C94%2C95%2C96%2C97%2C98%2C99%2C100%2C101%2C 102%2C103%2C104%2C105%2C106%2C108%2C110&fs%7Cgeslacht_id=15&fs%7Cleeftijdsgroep_id
=67%2C36%2C37%2C38%2C39%2C40%2C41&fs%7Cjaren_na_diagnose_id=16&fs%7Ceenheid_
id=2&cs%7Ctype=line&cs%7CxAxis=periode_id&cs%7Cseries=leeftijdsgroep_id&ts%7CrowDimen- sions=periode_id&ts%7CcolumnDimensions=leeftijdsgroep_id&lang%7Clanguage=nl.
3. Tjon Pian Gi, R E, San Giorgi MR, Slagter-Menkema L, et al. Clinical course of recurrent respiratory papillomatosis: Comparison between aggressiveness of human papillomavirus-6 and human papillomavirus-11. Head Neck. 2015;37(11):1625-1632.
4. Steuer CE, El-Deiry M, Parks JR, Higgins KA, Saba NF. An update on larynx cancer. CA Cancer J Clin.
2017;67(1):31-50.
5. Marshak G, Brenner B, Shvero J, et al. Prognostic factors for local control of early glottic cancer: The rabin medical center retrospective study on 207 patients. Int J Radiat Oncol Biol Phys. 1999;43(5):1009- 1013.
6. Schrijvers ML, van Riel EL, Langendijk JA, et al. Higher laryngeal preservation rate after CO2 laser surgery compared with radiotherapy in T1a glottic laryngeal carcinoma. Head Neck. 2009;31(6):759-764.
7. Hartl DM, Brasnu DF. Contemporary surgical management of early glottic cancer. Otolaryngol Clin North Am. 2015;48(4):611-625.
8. Feng Y, Wang B, Wen S. Laser surgery versus radiotherapy for T1-T2N0 glottic cancer: A meta-analysis.
ORL J Otorhinolaryngol Relat Spec. 2011;73(6):336-342.
9. Bonner JA, Harari PM, Giralt J, et al. Radiotherapy plus cetuximab for squamous-cell carcinoma of the head and neck. N Engl J Med. 2006;354(6):567-578.
10. Bonner JA, Harari PM, Giralt J, et al. Radiotherapy plus cetuximab for locoregionally advanced head and neck cancer: 5-year survival data from a phase 3 randomised trial, and relation between cetuximab- induced rash and survival. Lancet Oncol. 2010;11(1):21-28.
11. Winquist E, Agbassi C, Meyers BM, Yoo J, Chan KKW, Head and Neck Disease Site Group. Systemic therapy in the curative treatment of head and neck squamous cell cancer: A systematic review. J Otolaryngol Head Neck Surg. 2017;46(1):29.
12. Magrini SM, Buglione M, Corvo R, et al. Cetuximab and radiotherapy versus cisplatin and radiotherapy for locally advanced head and neck cancer: A randomized phase II trial. J Clin Oncol. 2016;34(5):427- 435.
13. Ow TJ, Pitts CE, Kabarriti R, Garg MK. Effective biomarkers and radiation treatment in head and neck cancer. Arch Pathol Lab Med. 2015;139(11):1379-1388.
14. Lefebvre JL. Laryngeal preservation in head and neck cancer: Multidisciplinary approach. Lancet Oncol.
2006;7(9):747-755.
15. Chera BS, Amdur RJ, Morris CG, Kirwan JM, Mendenhall WM. T1N0 to T2N0 squamous cell carcinoma of the glottic larynx treated with definitive radiotherapy. Int J Radiat Oncol Biol Phys. 2010;78(2):461-466.
16. Hartl DM, Ferlito A, Brasnu DF, et al. Evidence-based review of treatment options for patients with glottic cancer. Head Neck. 2011;33(11):1638-1648.
17. Dedivitis RA, Aires FT, Cernea CR, Brandão LG. Pharyngocutaneous fistula after total laryngectomy:
Systematic review of risk factors. Head Neck. 2015;37(11):1691-1697.
18. Eskiizmir G, Baskin Y, Yalcin F, Ellidokuz H, Ferris RL. Risk factors for radiation failure in early-stage glottic carcinoma: A systematic review and meta-analysis. Oral Oncol. 2016;62:90-100.
1
19. de Miguel-Luken MJ, Chaves-Conde M, Carnero A. A genetic view of laryngeal cancer heterogeneity.
Cell Cycle. 2016;15(9):1202-1212.
20. Noordhuis MG, Kop EA, van B, et al. Biological tumor markers associated with local control after primary radiotherapy in laryngeal cancer: A systematic review. Clin Otolaryngol. 2020.
21. Horsman MR, Overgaard J. The impact of hypoxia and its modification of the outcome of radiotherapy.
J Radiat Res. 2016;57 Suppl 1:i90-i98.
22. Vaupel P, Mayer A. Hypoxia in cancer: Significance and impact on clinical outcome. Cancer Metastasis Rev. 2007;26(2):225-239.
23. Janssen HL, Haustermans KM, Balm AJ, Begg AC. Hypoxia in head and neck cancer: How much, how important? Head Neck. 2005;27(7):622-638.
24. THOMLINSON RH, GRAY LH. The histological structure of some human lung cancers and the possible implications for radiotherapy. Br J Cancer. 1955;9(4):539-549.
25. GRAY LH, CONGER AD, EBERT M, HORNSEY S, SCOTT OC. The concentration of oxygen dissolved in tissues at the time of irradiation as a factor in radiotherapy. Br J Radiol. 1953;26(312):638-648.
26. Overgaard J. Hypoxic radiosensitization: Adored and ignored. J Clin Oncol. 2007;25(26):4066-4074.
27. Hoogsteen IJ, Marres HA, van der Kogel, A J, Kaanders JH. The hypoxic tumour microenvironment, patient selection and hypoxia-modifying treatments. Clin Oncol (R Coll Radiol). 2007;19(6):385-396.
28. Hammond EM, Asselin MC, Forster D, O’Connor JP, Senra JM, Williams KJ. The meaning, measurement and modification of hypoxia in the laboratory and the clinic. Clin Oncol (R Coll Radiol). 2014;26(5):277- 288.
29. Le QT, Denko NC, Giaccia AJ. Hypoxic gene expression and metastasis. Cancer Metastasis Rev.
2004;23(3-4):293-310.
30. Harris AL. Hypoxia--a key regulatory factor in tumour growth. Nat Rev Cancer. 2002;2(1):38-47.
31. Hill RP, Bristow RG, Fyles A, Koritzinsky M, Milosevic M, Wouters BG. Hypoxia and predicting radiation response. Semin Radiat Oncol. 2015;25(4):260-272.
32. Schrijvers ML, van der Laan, B F, de Bock GH, et al. Overexpression of intrinsic hypoxia markers HIF1alpha and CA-IX predict for local recurrence in stage T1-T2 glottic laryngeal carcinoma treated with radiotherapy. Int J Radiat Oncol Biol Phys. 2008;72(1):161-169.
33. Rischin D, Peters LJ, O’Sullivan B, et al. Tirapazamine, cisplatin, and radiation versus cisplatin and radiation for advanced squamous cell carcinoma of the head and neck (TROG 02.02, HeadSTART): A phase III trial of the trans-tasman radiation oncology group. J Clin Oncol. 2010;28(18):2989-2995.
34. Thorwarth D, Eschmann SM, Paulsen F, Alber M. A model of reoxygenation dynamics of head-and- neck tumors based on serial 18F-fluoromisonidazole positron emission tomography investigations. Int J Radiat Oncol Biol Phys. 2007;68(2):515-521.
35. Janssens GO, Rademakers SE, Terhaard CH, et al. Accelerated radiotherapy with carbogen and nicotinamide for laryngeal cancer: Results of a phase III randomized trial. J Clin Oncol. 2012;30(15):1777- 1783.
36. Nordsmark M, Overgaard M, Overgaard J. Pretreatment oxygenation predicts radiation response in advanced squamous cell carcinoma of the head and neck. Radiother Oncol. 1996;41(1):31-39.
37. Brizel DM, Sibley GS, Prosnitz LR, Scher RL, Dewhirst MW. Tumor hypoxia adversely affects the prognosis of carcinoma of the head and neck. Int J Radiat Oncol Biol Phys. 1997;38(2):285-289.
38. Nordsmark M, Bentzen SM, Rudat V, et al. Prognostic value of tumor oxygenation in 397 head and neck tumors after primary radiation therapy. an international multi-center study. Radiother Oncol.
2005;77(1):18-24.
39. Nordsmark M, Loncaster J, Aquino-Parsons C, et al. The prognostic value of pimonidazole and tumour pO2 in human cervix carcinomas after radiation therapy: A prospective international multi-center study. Radiother Oncol. 2006;80(2):123-131.
40. Becker A, Hansgen G, Bloching M, Weigel C, Lautenschlager C, Dunst J. Oxygenation of squamous cell carcinoma of the head and neck: Comparison of primary tumors, neck node metastases, and normal tissue. Int J Radiat Oncol Biol Phys. 1998;42(1):35-41.
41. Dhani N, Fyles A, Hedley D, Milosevic M. The clinical significance of hypoxia in human cancers. Semin Nucl Med. 2015;45(2):110-121.
42. Hoogsteen IJ, Marres HA, Bussink J, van der Kogel, A J, Kaanders JH. Tumor microenvironment in head and neck squamous cell carcinomas: Predictive value and clinical relevance of hypoxic markers. A review. Head Neck. 2007;29(6):591-604.
43. Raleigh JA, Calkins-Adams DP, Rinker LH, et al. Hypoxia and vascular endothelial growth factor expression in human squamous cell carcinomas using pimonidazole as a hypoxia marker. Cancer Res.
1998;58(17):3765-3768.
44. Kaanders JH, Wijffels KI, Marres HA, et al. Pimonidazole binding and tumor vascularity predict for treatment outcome in head and neck cancer. Cancer Res. 2002;62(23):7066-7074.
45. Vaupel P, Multhoff G. Fatal alliance of hypoxia-/HIF-1α-driven microenvironmental traits promoting cancer progression. Adv Exp Med Biol. 2020;1232:169-176.
46. Semenza GL. Targeting HIF-1 for cancer therapy. Nat Rev Cancer. 2003;3(10):721-732.
47. Nordsmark M, Eriksen JG, Gebski V, Alsner J, Horsman MR, Overgaard J. Differential risk assessments from five hypoxia specific assays: The basis for biologically adapted individualized radiotherapy in advanced head and neck cancer patients. Radiother Oncol. 2007;83(3):389-397.
48. Kwon OJ, Park JJ, Ko GH, et al. HIF-1α and CA-IX as predictors of locoregional control for determining the optimal treatment modality for early-stage laryngeal carcinoma. Head Neck. 2015;37(4):505-510.
49. Koukourakis MI, Giatromanolaki A, Sivridis E, et al. Hypoxia-regulated carbonic anhydrase-9 (CA9) relates to poor vascularization and resistance of squamous cell head and neck cancer to chemoradiotherapy.
Clin Cancer Res. 2001;7(11):3399-3403.
50. Koukourakis MI, Bentzen SM, Giatromanolaki A, et al. Endogenous markers of two separate hypoxia response pathways (hypoxia inducible factor 2 alpha and carbonic anhydrase 9) are associated with radiotherapy failure in head and neck cancer patients recruited in the CHART randomized trial. J Clin Oncol. 2006;24(5):727-735.
51. Rademakers SE, Hoogsteen IJ, Rijken PF, et al. Pattern of CAIX expression is prognostic for outcome and predicts response to ARCON in patients with laryngeal cancer treated in a phase III randomized trial.
Radiother Oncol. 2013;108(3):517-522.
52. Fang J, Zhou SH, Fan J, Yan SX. Roles of glucose transporter-1 and the phosphatidylinositol 3-kinase/
protein kinase B pathway in cancer radioresistance (review). Mol Med Rep. 2015;11(3):1573-1581.
53. Jonathan RA, Wijffels KI, Peeters W, et al. The prognostic value of endogenous hypoxia-related markers for head and neck squamous cell carcinomas treated with ARCON. Radiother Oncol. 2006;79(3):288- 297.
54. Airley RE, Loncaster J, Raleigh JA, et al. GLUT-1 and CAIX as intrinsic markers of hypoxia in carcinoma of the cervix: Relationship to pimonidazole binding. Int J Cancer. 2003;104(1):85-91.
55. Airley R, Loncaster J, Davidson S, et al. Glucose transporter glut-1 expression correlates with tumor hypoxia and predicts metastasis-free survival in advanced carcinoma of the cervix. Clin Cancer Res.
2001;7(4):928-934.
56. Sorensen BS, Hao J, Overgaard J, et al. Influence of oxygen concentration and pH on expression of hypoxia induced genes. Radiother Oncol. 2005;76(2):187-193.
57. Hoogsteen IJ, Peeters WJ, Marres HA, et al. Erythropoietin receptor is not a surrogate marker for tumor hypoxia and does not correlate with survival in head and neck squamous cell carcinomas. Radiother Oncol. 2005;76(2):213-218.
58. Wedman J, Pruim J, Roodenburg JL, et al. Alternative PET tracers in head and neck cancer. A review. Eur Arch Otorhinolaryngol. 2013;270(10):2595-2601.
59. Troost EG, Laverman P, Kaanders JH, et al. Imaging hypoxia after oxygenation-modification: Comparing [18F]FMISO autoradiography with pimonidazole immunohistochemistry in human xenograft tumors.
Radiother Oncol. 2006;80(2):157-164.
60. Gagel B, Piroth M, Pinkawa M, et al. pO polarography, contrast enhanced color duplex sonography (CDS), [18F] fluoromisonidazole and [18F] fluorodeoxyglucose positron emission tomography: Validated methods for the evaluation of therapy-relevant tumor oxygenation or only bricks in the puzzle of tumor hypoxia? BMC Cancer. 2007;7:113-2407.
61. Rajendran JG, Schwartz DL, O’Sullivan J, et al. Tumor hypoxia imaging with [F-18] fluoromisonidazole positron emission tomography in head and neck cancer. Clin Cancer Res. 2006;12(18):5435-5441.
62. Rischin D, Hicks RJ, Fisher R, et al. Prognostic significance of [18F]-misonidazole positron emission tomography-detected tumor hypoxia in patients with advanced head and neck cancer randomly
1
assigned to chemoradiation with or without tirapazamine: A substudy of trans-tasman radiation oncology group study 98.02. J Clin Oncol. 2006;24(13):2098-2104.
63. Hicks RJ, Rischin D, Fisher R, Binns D, Scott AM, Peters LJ. Utility of FMISO PET in advanced head and neck cancer treated with chemoradiation incorporating a hypoxia-targeting chemotherapy agent. Eur J Nucl Med Mol Imaging. 2005;32(12):1384-1391.
64. Zips D, Zophel K, Abolmaali N, et al. Exploratory prospective trial of hypoxia-specific PET imaging during radiochemotherapy in patients with locally advanced head-and-neck cancer. Radiother Oncol.
2012;105(1):21-28.
65. Mortensen LS, Johansen J, Kallehauge J, et al. FAZA PET/CT hypoxia imaging in patients with squamous cell carcinoma of the head and neck treated with radiotherapy: Results from the DAHANCA 24 trial.
Radiother Oncol. 2012;105(1):14-20.
66. Sorger D, Patt M, Kumar P, et al. 18F]fluoroazomycinarabinofuranoside (18FAZA) and [18F]
fluoromisonidazole (18FMISO): A comparative study of their selective uptake in hypoxic cells and PET imaging in experimental rat tumors. Nucl Med Biol. 2003;30(3):317-326.
67. Piert M, Machulla HJ, Picchio M, et al. Hypoxia-specific tumor imaging with 18F-fluoroazomycin arabinoside. J Nucl Med. 2005;46(1):106-113.
68. Hynes NE, Lane HA. ERBB receptors and cancer: The complexity of targeted inhibitors. Nat Rev Cancer.
2005;5(5):341-354.
69. Sharafinski ME, Ferris RL, Ferrone S, Grandis JR. Epidermal growth factor receptor targeted therapy of squamous cell carcinoma of the head and neck. Head Neck. 2010;32(10):1412-1421.
70. Grandis JR, Tweardy DJ. Elevated levels of transforming growth factor alpha and epidermal growth factor receptor messenger RNA are early markers of carcinogenesis in head and neck cancer. Cancer Res. 1993;53(15):3579-3584.
71. Ang KK, Berkey BA, Tu X, et al. Impact of epidermal growth factor receptor expression on survival and pattern of relapse in patients with advanced head and neck carcinoma. Cancer Res. 2002;62(24):7350- 7356.
72. Chang AR, Wu HG, Park CI, Jun YK, Kim CW. Expression of epidermal growth factor receptor and cyclin D1 in pretreatment biopsies as a predictive factor of radiotherapy efficacy in early glottic cancer. Head Neck. 2008;30(7):852-857.
73. Demiral AN, Sarioglu S, Birlik B, Sen M, Kinay M. Prognostic significance of EGF receptor expression in early glottic cancer. Auris Nasus Larynx. 2004;31(4):417-424.
74. Chung CH, Zhang Q, Hammond EM, et al. Integrating epidermal growth factor receptor assay with clinical parameters improves risk classification for relapse and survival in head-and-neck squamous cell carcinoma. Int J Radiat Oncol Biol Phys. 2011;81(2):331-338.
75. Licitra L, Störkel S, Kerr KM, et al. Predictive value of epidermal growth factor receptor expression for first-line chemotherapy plus cetuximab in patients with head and neck and colorectal cancer: Analysis of data from the EXTREME and CRYSTAL studies. Eur J Cancer. 2013;49(6):1161-1168.
76. Worby CA, Dixon JE. Pten. Annu Rev Biochem. 2014;83:641-669.
77. Song MS, Salmena L, Pandolfi PP. The functions and regulation of the PTEN tumour suppressor. Nat Rev Mol Cell Biol. 2012;13(5):283-296.
78. Okami K, Wu L, Riggins G, et al. Analysis of PTEN/MMAC1 alterations in aerodigestive tract tumors.
Cancer Res. 1998;58(3):509-511.
79. Poetsch M, Lorenz G, Kleist B. Detection of new PTEN/MMAC1 mutations in head and neck squamous cell carcinomas with loss of chromosome 10. Cancer Genet Cytogenet. 2002;132(1):20-24.
80. Shao X, Tandon R, Samara G, et al. Mutational analysis of the PTEN gene in head and neck squamous cell carcinoma. Int J Cancer. 1998;77(5):684-688.
81. Yokota T. Is biomarker research advancing in the era of personalized medicine for head and neck cancer? Int J Clin Oncol. 2014;19(2):211-219.
82. Liu W, Zhou Y, Reske SN, Shen C. PTEN mutation: Many birds with one stone in tumorigenesis.
Anticancer Res. 2008;28(6A):3613-3619.
83. Pattje WJ, Schuuring E, Mastik MF, et al. The phosphatase and tensin homologue deleted on chromosome 10 mediates radiosensitivity in head and neck cancer. Br J Cancer. 2010;102(12):1778-1785.
84. Shen WH, Balajee AS, Wang J, et al. Essential role for nuclear PTEN in maintaining chromosomal integrity. Cell. 2007;128(1):157-170.
85. Thoms J, Bristow RG. DNA repair targeting and radiotherapy: A focus on the therapeutic ratio. Semin Radiat Oncol. 2010;20(4):217-222.
86. Chehab NH, Malikzay A, Appel M, Halazonetis TD. Chk2/hCds1 functions as a DNA damage checkpoint in G(1) by stabilizing p53. Genes Dev. 2000;14(3):278-288.
87. Shieh SY, Ahn J, Tamai K, Taya Y, Prives C. The human homologs of checkpoint kinases Chk1 and Cds1 (Chk2) phosphorylate p53 at multiple DNA damage-inducible sites. Genes Dev. 2000;14(3):289-300.
88. Banin S, Moyal L, Shieh S, et al. Enhanced phosphorylation of p53 by ATM in response to DNA damage.
Science. 1998;281(5383):1674-1677.
89. Hirao A, Kong YY, Matsuoka S, et al. DNA damage-induced activation of p53 by the checkpoint kinase Chk2. Science. 2000;287(5459):1824-1827.
90. Canman CE, Lim DS, Cimprich KA, et al. Activation of the ATM kinase by ionizing radiation and phosphorylation of p53. Science. 1998;281(5383):1677-1679.
91. Shiloh Y. ATM and related protein kinases: Safeguarding genome integrity. Nat Rev Cancer.
2003;3(3):155-168.
92. Roossink F, Wieringa HW, Noordhuis MG, et al. The role of ATM and 53BP1 as predictive markers in cervical cancer. Int J Cancer. 2012;131(9):2056-2066.
93. Zou J, Qiao X, Ye H, et al. Inhibition of ataxia-telangiectasia mutated by antisense oligonucleotide nanoparticles induces radiosensitization of head and neck squamous-cell carcinoma in mice. Cancer Biother Radiopharm. 2009;24(3):339-346.
94. Dohmen AJC, Qiao X, Duursma A, et al. Identification of a novel ATM inhibitor with cancer cell specific radiosensitization activity. Oncotarget. 2017;8(43):73925-73937.
95. Condon LT, Ashman JN, Ell SR, Stafford ND, Greenman J, Cawkwell L. Overexpression of bcl-2 in squamous cell carcinoma of the larynx: A marker of radioresistance. Int J Cancer. 2002;100(4):472-475.
96. Lim AM, Young RJ, Collins M, et al. Correlation of ataxia-telangiectasia-mutated (ATM) gene loss with outcome in head and neck squamous cell carcinoma. Oral Oncol. 2012;48(8):698-702.
97. Zhang W, Xu J. DNA methyltransferases and their roles in tumorigenesis. Biomark Res. 2017;5:1-017.
98. Jones PA, Baylin SB. The fundamental role of epigenetic events in cancer. Nat Rev Genet. 2002;3(6):415- 428.
99. Herman JG, Baylin SB. Gene silencing in cancer in association with promoter hypermethylation. N Engl J Med. 2003;349(21):2042-2054.
100. Lewandowska J, Bartoszek A. DNA methylation in cancer development, diagnosis and therapy--multiple opportunities for genotoxic agents to act as methylome disruptors or remediators. Mutagenesis.
2011;26(4):475-487.
101. Melchers LJ, Clausen MJ, Mastik MF, et al. Identification of methylation markers for the prediction of nodal metastasis in oral and oropharyngeal squamous cell carcinoma. Epigenetics. 2015;10(9):850- 860.
102. Clausen MJ, Melchers LJ, Mastik MF, et al. Identification and validation of WISP1 as an epigenetic regulator of metastasis in oral squamous cell carcinoma. Genes Chromosomes Cancer. 2016;55(1):45- 59.
103. Clausen MJ, Melchers LJ, Mastik MF, et al. RAB25 expression is epigenetically downregulated in oral and oropharyngeal squamous cell carcinoma with lymph node metastasis. Epigenetics. 2016;11(9):653-663.
104. Azad N, Zahnow CA, Rudin CM, Baylin SB. The future of epigenetic therapy in solid tumours--lessons from the past. Nat Rev Clin Oncol. 2013;10(5):256-266.
105. Ahuja N, Easwaran H, Baylin SB. Harnessing the potential of epigenetic therapy to target solid tumors.
J Clin Invest. 2014;124(1):56-63.
106. Esteller M. Epigenetics in cancer. N Engl J Med. 2008;358(11):1148-1159.
107. Zhao SL, Zhu ST, Hao X, Li P, Zhang ST. Effects of DNA methyltransferase 1 inhibition on esophageal squamous cell carcinoma. Dis Esophagus. 2011;24(8):601-610.
108. Wu S, Wang X, Chen JX, Chen Y. Predictive factors for the sensitivity of radiotherapy and prognosis of esophageal squamous cell carcinoma. Int J Radiat Biol. 2014;90(5):407-413.
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109. Chen MF, Chen WC, Chang YJ, Wu CF, Wu CT. Role of DNA methyltransferase 1 in hormone-resistant prostate cancer. J Mol Med (Berl). 2010;88(9):953-962.
110. De Schutter H, Kimpe M, Isebaert S, Nuyts S. A systematic assessment of radiation dose enhancement by 5-aza-2’-deoxycytidine and histone deacetylase inhibitors in head-and-neck squamous cell carcinoma. Int J Radiat Oncol Biol Phys. 2009;73(3):904-912.
111. Zielske SP. Epigenetic DNA methylation in radiation biology: On the field or on the sidelines? J Cell Biochem. 2015;116(2):212-217.
112. Roossink F, de Jong S, Wisman GB, van der Zee, A G, Schuuring E. DNA hypermethylation biomarkers to predict response to cisplatin treatment, radiotherapy or chemoradiation: The present state of art. Cell Oncol (Dordr). 2012;35(4):231-241.
Chapter 2
Head and neck tumor hypoxia imaging by 18 F-fluoroazomycin-
arabinoside ( 18 F-FAZA)-PET:
a review
GB Halmosa, L Bruine de Bruina,b,†, JA Langendijkd, BFAM van der Laana,#, J Pruimc, RJHM Steenbakkersd
aDepartment of Otorhinolaryngology/Head and Neck Surgery,University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
bDepartment of Pathology and Medical Biology,University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
cDepartment of Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Center Groningen, The Netherlands and Department of Nuclear Medicine, Tygerberg Hospital, Stellenbosch University, Stellenbosch, South-Africa
dDepartment of Radiation Oncology,University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
†Current affiliation: Department of Otorhinolaryngology/Head and Neck Surgery, Hospital St Jansdal, Harderwijk/Lelystad, The Netherlands
#Current affiliation: Department of Otorhinolaryngology/Head and Neck Surgery, Haaglanden Medical Center, The Hague, The Netherlands
Published in: Clinical Nuclear Medicine. 2014 Jan;39(1):44-48
ABSTRACT
Tumor hypoxia is known to be associated with poor clinical outcome; therefore, patients with hypoxic tumors might benefit from more intensive treatment approaches. This is particularly true for patients with head and neck cancer. Pre- treatment assessment of hypoxia in tumors would be desirable, not only to predict prognosis but also to select patients for more aggressive treatment.
As an alternative to the invasive polarographic needle electrode method, there is the possibility of using PET with radiopharmaceuticals visualizing hypoxia. Most hypoxia imaging studies on head and cancer have been performed using 18F-labeled fluoromisonidazole (18F-FMISO). A chemically related molecule, 18F-fluoroazomycin- arabinoside (18F-FAZA), seems to have superior kinetic properties and may therefore be the radiopharmaceutical of choice.
This minireview summarizes the published literature on animal and human
18F-FAZA-PET studies. Furthermore, future perspectives on how individualized treatment could be applied in patients with hypoxic head and neck tumors are discussed, for instance the use of hypoxia sensitizers or special intensity modulated radiation therapy techniques achieving tumor subvolume dose escalation.
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INTRODUCTION
Tumor hypoxia
Tumor hypoxia is a well-recognized adverse prognostic factor in patients with solid tumors treated with radiotherapy1 and is associated with a number of unfavorable biological characteristics, including increased genetic instability, increased invasiveness, enhanced metastatic potential and decreased radiosensitivity2,3. Poorer clinical outcome of hypoxic tumors has been observed in patients with head and neck cancer treated by radiotherapy4,5 and surgery6. From this point of view, patients with hypoxic tumors might benefit from more intensive treatment approaches to counterbalance the radioresistance. It has been estimated that tumor hypoxia is present in about half of the solid tumors regardless of the tumor volume or histological type7. Unfortunately, patients with head and neck cancer tend to present themselves with tumors in advanced stages, which increase the likelihood of developing hypoxia8.
Detection of hypoxia
Although tumor hypoxia is usually defined as a tumor region with a partial oxygen pressure (pO2) less than 10 mm Hg9, there is no consensus over the interpretation and analysis of hypoxia-positive areas of different imaging modalities. For instance, some of the PET studies use the tumor-to-background ratio (T/B), others the tumor-to-muscle ratio (T/M) and there are also self-developed scoring systems.
Unfortunately, these differences make it difficult to compare studies.
Polarographic needle electrode sampling is considered the gold standard to assess hypoxia in vivo10,11. However, assessing tumor hypoxia using the Eppendorf electrodes is invasive, requires sophisticated skills and technical demands and may be subject to sampling error because of the known heterogeneity in tumor hypoxia12,13. In addition, the results of these measurements cannot be used for radiotherapy treatment planning, for example, for escalating the dose to hypoxic regions within a tumor.
Therefore, assessing tumor hypoxia with metabolic imaging techniques such as PET, using specific radiopharmaceuticals visualizing hypoxia, is an attractive alternative, at least theoretically. Several studies have been published and several different radiopharmaceuticals have been applied. Due to the different analysis techniques applied, however, it is difficult to compare studies even using the same PET radiopharmaceuticals (Table 1).
Table 1. Summary of studies on human 18F-FAZA-PET
Publication No. patients Tumor site (n) Definition of
hypoxic volume Percentage of patients with increased 18F-FAZA uptake
(ie, hypoxia) Grosu et al.16 and
Souvatzoglou et al.43 18 Head and neck
(18) T/M ≥ 1.5* 83
Postema et al.44 50 Head and neck (9) Lymphoma (21)
High-grade glioma (7)
Lung (13)
Visual inspection
and T/B ratio ≥ 1.2 66
14 10054
Schuetz et al.45 15 Cervix (15) T/M ≥ 1.2† 33
Shi et al.46 5 Head and neck
(5) Different kinetic
models 80
Garcia-Parra et al.47 14 Prostate (14) T/B ratio‡ 0
Mortensen et al.48 40 Head and neck
(40) T/M ≥ 1.4§ 63
Bollineni et al.49 11 Lung (11) T/B ratio ≥ 1.2 and
T/B ratio ≥ 1.4 100
*Tumor SUV/muscle SUVmean ratio ≥ 1.5.
†Tumor SUVmax/muscle SUVmax ratio ≥ 1.2.
‡Tumor SUVmax/benign prostate SUV.
§Tumor SUVmax/muscle SUV mean ratio ≥ 1.4.
18F-FMISO for hypoxia imaging
A number of PET radiopharmaceuticals for hypoxia imaging have been identified, of which the group of nitroimidazoles is the largest. These compounds undergo reduction under hypoxic conditions and form highly reactive oxygen radicals.
After binding to intracellular macromolecules, they are trapped inside the hypoxic cells. Among the radiolabeled nitroimidazoles, 18F-FMISO is the most frequently used. Troost et al.14 found a significant correlation between 18F-FMISO-PET imaging of tumor hypoxia in head and neck cancer and the extrinsic hypoxic cell marker pimonidazole. Pimonidazole is a nitroimidazole-like robust exogenous hypoxia marker, which needs to be injected 2 hours before biopsy. The distribution of pimonidazole is visualized by immunohistochemistry. In another validation study, only a week correlation was found between 18F-FMISO uptake and pO2 histography15. These apparently conflicting results are most likely due to heterogeneity in intratumoral hypoxia16. In a study of 73 patients with head and neck cancer, hypoxia, defined by increased 18F-FMISO uptake, was found in almost 80% of the patients. Moreover, increased 18F-FMISO uptake found to be associated with significant worse overall survival17. Rischin and co-workers18 also found 18F-FMISO effective in determining hypoxic regions in head and neck carcinoma. In that study,
2
tirapazamine (a hypoxic cytotoxin), was found to be effective in patients with hypoxic tumors as assessed by 18F-FMISO-PET. Pre-treatment dynamic 18F-FMISO- PET scanning has also found to be successful in predicting radiotherapy outcome in non-small cell lung cancer and head and neck cancer19,20. Moreover, a later study of the same group21 showed that the same imaging technique is also suitable for following the radio-induced reoxygenation of head and neck cancer during radiotherapy. A recent study by Zips et al.22 investigated the change of hypoxia and the predictive value of it for survival during radiotherapy in patients with head and neck cancer using 18F-FMISO-PET scan. Each patient has been scanned before and three times during radiotherapy. The scan parameters performed at week 1 (8-10 Gy) and 2 (18-20 Gy) strongly correlated with the local progression-free survival endpoints, suggesting good prognostic value of 18F-FMISO-PET at these time points and not at baseline.
Most of the studies investigating hypoxia by PET scans using static scans, as technically static scans are easier to perform. However, dynamic scans are more informative as they allow kinetic modeling and estimation of some rate constants, which can discriminate between tumor and background.
Alternatives to 18F-FMISO
Although hypoxia imaging using 18F-FMISO-PET is feasible and has prognostic value, there are also some disadvantages using this PET radiopharmaceutical. One of the problems is the relatively short half-life time (110 minutes) of 18F-FMISO, which hampers late imaging that could enhance good contrast between hypoxia and normal tissues23. There is ongoing intensive research in order to find alternative hypoxia PET radiopharmaceuticals with better kinetics. 18F-HX4, another new potential marker for hypoxia PET scanning has recently been described24. Preclinical studies showed advantageous biodistribution and dosimetry properties, which make 18F-HX4 a promising hypoxia radiopharmaceutical candidate. A pilot PET study on hypoxia imaging using 18F-HX4 as a radiopharmaceutical in head and neck cancer patient has recently been published25. Although this study included only 12 patients, the data are promising; higher sensitivity, specificity, faster clearance, and shorter injection-imaging time were found compared to 18F-FMISO. 18F-EF5 is another nitroimidazole that has been evaluated in imaging hypoxia in patients with head and neck squamous cell carcinoma. Data showed that the later uptake and binding of 18F-EF5 are hypoxia specific. The optimal scanning time and the appropriate T/M have also been established26. Head and neck tumor hypoxia has
also been assessed by 18F-FETNIM27. In a later study, high uptake of 18F-FETNIM seemed to correlate with poorer radiotherapy outcome, although firm conclusions are difficult to draw due to small study population28. Beside these nitroimidazoles, other molecules have been also tested, like the dithiosemicarbazones. One of them is 64Cu-ATSM, which is also a PET radiopharmaceutical developed to accumulate in hypoxic tumors. It found to be feasible for radiotherapy planning in a pilot study, and the biokinetic properties seems to be superior to 18F-FMISO, as a hypoxic tumor subvolume could be identified as early as 10 minutes after injection29.
Purpose of the present review
In this review, we will focus on the possible applicability of PET scanning with a relatively new hypoxia radiopharmaceutical, 18F-FAZA, in radiotherapy treatment planning based on tumor hypoxia determination in head and neck cancer.
More specifically, the purposes of this review are to assess whether hypoxia as determined with 18F-FAZA-PET correlates with histological or biological parameters, to investigate whether the presence of hypoxia as demonstrated with 18F-FAZA predicts outcome and to investigate how 18F-FAZA could be used in clinical practice.
PROPERTIES OF
18F-FAZA
18F-FAZA is, like 18F-FMISO, a 2-nitroimidazole compound, but sugar-coupled (Figure 1). As already mentioned, 2-nitroimidazole compounds undergo reduction under hypoxic conditions, forming highly reactive oxygen radicals. Subsequently, they bind to macromolecules in the intracellular compartment and trapped inside hypoxic cells30. When 18F-FAZA is labeled with the radioisotope 18F, it can be detected by a PET scanner.
Kumar et al31 were the first that reported on the synthesis of 18F-FAZA by fluorination of 1-α-D-(2,3-di-O-acetylarabinofuranosyl)-2-nitroimidazole with DAST followed by deprotection. Their main objective was to develop a PET imaging compound that was similar to the SPECT compound 123I-IAZA, but that was less lipophilic than 18F-FMISO. Theoretically, a less lipophilic compound may produce higher perfusion and faster clearance from blood resulting in a better hypoxia-background-ratio. In a rat model, they showed that 3H-FAZA had similar biodistribution, tumor uptake, and pharmacokinetics as 123I-IAZA, but was indeed less lipophilic than 18F-FMISO.
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Figure 1. Molecular structure of 18F-FAZA
IN VITRO
18F-FAZA EXPERIMENTS AND
18F-FAZA-PET XENOGRAFT MODELS
As all new radiopharmaceuticals, 18F-FAZA is also intensively investigated in both in vitro and in vivo experiments. The detection of hypoxia-dependent radiopharmaceutical accumulation is fundamental, just like exact characterization of pharmacokinetic features.
In the first in vitro study by Busk et al.32, oxygenation-dependent 18F-FAZA retention was compared to that of 18F-FDG in different carcinoma lines. 18F-FAZA accumulation was measured after radiopharmaceutical incubation in different oxygenation conditions. Significant 18F-FAZA retention was observed after 3 hours of anoxia and no binding in nonhypoxic cells. Furthermore, it showed superior in vivo hypoxia specificity compared with 18F-FDG. This study concluded that 18F-FAZA has excellent in vitro characteristics for hypoxia imaging. Another study33 compared the hypoxia-selective uptake of 18F-FAZA to that of 18F-FMISO, as the mostly used hypoxia radiopharmaceutical, and found no differences in the vitro experiments with tumor cell lines, but in the in vivo animal PET study the elimination of
18F-FAZA was found to be faster. This feature seems to be an advantage in imaging, but the concentration of 18F-FAZA was lower, which suggests a lower sensitivity of 18F-FAZA. In a later animal PET study, obvious superior biokinetics for 18F-FAZA were found as compared to 18F-FMISO, for example, significantly higher T/M and tumor-to-blood ratios34.
