Misonidazole combined with split-course radiotherapy in the treatment of invasive carcinoma of larynx and pharynx: report from the DAHANCA 2 study

Influence of 2-Nitroimidazoles in the Response of FaDu Cells to Ionizing Radiation and Hypoxia/Reoxygenation Stress

Cellular adaptations to hypoxia promote resistance to ionizing radiation (IR). This presents a challenge for treatment of head and neck cancer (HNC) that relies heavily on radiotherapy. Standard radiosensitizers often fail to reach diffusion-restricted hypoxic cells, whereas nitroimidazoles (NIs) [such as iodoazomycin arabinofuranoside (IAZA) and fluoroazomycin arabinofuranoside (FAZA)] can preferentially accumulate in hypoxic tumours. Here, we explored if the hypoxia-selective uptake of IAZA and FAZA could be harnessed to make HNC cells (FaDu) susceptible to radiation therapy. Cellular response to treatment was assessed through clonogenic survival assays and by monitoring DNA damage (immunofluorescence staining of DNA damage markers, γ-H2AX and p-53BP1, and by alkaline comet assay). The effects of reoxygenation were studied using the following assays: estimation of nucleoside incorporation to assess DNA synthesis rates, immunofluorescent imaging of chromatin-associated replication protein A as a marker of replication stress, and quantification of reactive oxygen species (ROS). Both IAZA and FAZA sensitized hypoxic HNC cells to IR, albeit the former is a better radiosensitizer. Radiosensitization by these compounds was restricted only to hypoxic cells, with no visible effects under normoxia. IAZA and FAZA impaired cellular adaptation to reoxygenation; high levels of ROS, reduced DNA synthesis capacity, and signs of replication stress were observed in reoxygenated cells. Overall, our data highlight the therapeutic potentials of IAZA and FAZA for targeting hypoxic HNC cells and provide rationale for future preclinical studies.

Defining the optimal threshold and prognostic utility of pre-treatment hemoglobin level as a biomarker for survival outcomes in head and neck cancer patients receiving chemoradiation

OBJECTIVES

We sought to define the optimal threshold for anemia in North American head and neck cancer patients and evaluate its role as a prognostic biomarker.

MATERIALS AND METHODS

A single-institution database was queried for patients with head and neck cancer who underwent chemoradiation from January 2005 to April 2021. An optimal threshold of hemoglobin (Hgb) level was defined based on maximum log-rank test statistic. Cox multivariable analysis (MVA), Kaplan-Meier, and propensity score matching were performed to evaluate treatment outcomes.

RESULTS

A total of 496 patients were identified. Threshold for Hgb was determined to be 11.4 for both overall survival (OS) and progression-free survival (PFS). Low Hgb was associated with worse OS (adjusted hazards ratio [aHR] 2.41, 95 % confidence interval [CI] 1.53-3.80, p < 0.001) and PFS (aHR 2.01, 95 % CI 1.30-3.11, p = 0.002). Similar findings were observed among 39 matched pairs for OS (5-year OS 22.3 % vs 49.0 %; HR 2.22, 95 % CI 1.23-4.03, p = 0.008) and PFS (5-year PFS 24.3 % vs 39.1 %; HR 1.78, 95 % CI 1.02-3.12, p = 0.04). Among those with HPV-negative tumors, low Hgb was associated with worse OS (aHR 13.90, 95 % CI 4.66-41.44, p < 0.001) and PFS (aHR 5.24, 95 % CI 2.09-13.18, p < 0.001). However, among those with HPV-positive tumors, low Hgb was not associated with both OS (aHR 1.75, 95 % CI 0.60-5.09, p = 0.31) and PFS (aHR 1.13, 95 % CI 0.41-3.14, p = 0.82).

CONCLUSION AND RELEVANCE

Low Hgb below 11.4 was an independent adverse prognostic factor for worse survival. It was also prognostic among patients with HPV-negative tumors, but not for HPV-positive tumors.

The Therapeutic Potential of Imidazole or Quinone-Based Compounds as Radiosensitisers in Combination with Radiotherapy for the Treatment of Head and Neck Squamous Cell Carcinoma

Simple Summary

Patients with curable head and neck cancers are usually treated with a combination of chemotherapy and radiotherapy, but they experience significant, severe side effects, which greatly affect their quality of life. Some of these patients still experience disease relapse after an intensive course of treatment due to tumours that are resistant to radiotherapy and chemotherapy because of hypoxia (lack of oxygen). In addition, some patients are not suitable for and/or are not able to have combined chemotherapy with radiotherapy due to their age or other physical conditions. Certain small-molecule drugs, which are used to treat various infections including malaria, have been shown to reduce hypoxia and thus make radiotherapy more effective. Therefore, their combination with radiotherapy could have less toxicities compared with the combination of chemotherapy with radiotherapy. Here, we discuss the promising results from preclinical work and clinical trials of these agents, and their potential use in the clinic, to reduce hypoxia and to sensitise radiotherapy. These agents could potentially be used for patients who are not suitable for combined chemotherapy and radiotherapy; they may also be used to reduce the dose of radiotherapy if able to enhance radiotherapy effect at lower dose in order to reduce toxicities while maintaining the treatment efficacy in a more personalised manner.

Abstract

The addition of platinum chemotherapy to primary radiotherapy (chemoradiation) improves survival outcomes for patients with head and neck squamous cell carcinoma (HNSCC), but it carries a high incidence of acute and long-term treatment-related complications, resulting in a poor quality of life. In addition, patients with significant co-morbidities, or older patients, cannot tolerate or do not benefit from concurrent chemoradiation. These patients are often treated with radiotherapy alone resulting in poor locoregional control and worse survival outcomes. Thus, there is an urgent need to assess other less toxic treatment modalities, which could become an alternative to chemoradiation in HNSCC. Currently, there are several promising anti-cancer drugs available, but there has been very limited success so far in replacing concurrent chemoradiation due to their low efficacy or increased toxicities. However, there is new hope that a treatment strategy that incorporates agents that act as radiosensitisers to improve the efficacy of conventional radiotherapy could be an alternative to more toxic chemotherapeutic agents. Recently, imidazole-based or quinone-based anti-malarial compounds have drawn considerable attention as potential radiosensitisers in several cancers. Here, we will discuss the possibility of using these compounds as radiosensitisers, which could be assessed as safe and effective alternatives to chemotherapy, particularly for patients with HNSCC that are not suitable for concurrent chemotherapy due to their age or co-morbidities or in metastatic settings. In addition, these agents could also be tested to assess their efficacy in combination with immunotherapy in recurrent and metastatic settings or in combination with radiotherapy and immunotherapy in curative settings.

Overcoming the Impact of Hypoxia in Driving Radiotherapy Resistance in Head and Neck Squamous Cell Carcinoma

Hypoxia is very common in most solid tumours and is a driving force for malignant progression as well as radiotherapy and chemotherapy resistance. Incidences of head and neck squamous cell carcinoma (HNSCC) have increased in the last decade and radiotherapy is a major therapeutic technique utilised in the treatment of the tumours. However, effectiveness of radiotherapy is hindered by resistance mechanisms and most notably by hypoxia, leading to poor patient prognosis of HNSCC patients. The phenomenon of hypoxia-induced radioresistance was identified nearly half a century ago, yet despite this, little progress has been made in overcoming the physical lack of oxygen. Therefore, a more detailed understanding of the molecular mechanisms of hypoxia and the underpinning radiobiological response of tumours to this phenotype is much needed. In this review, we will provide an up-to-date overview of how hypoxia alters molecular and cellular processes contributing to radioresistance, particularly in the context of HNSCC, and what strategies have and could be explored to overcome hypoxia-induced radioresistance.

FMISO-Based Adaptive Radiotherapy in Head and Neck Cancer

Concurrent chemoradiotherapy represents one of the most used strategies in the curative treatment of patients with head and neck (HNC) cancer. Locoregional failure is the predominant recurrence pattern. Tumor hypoxia belongs to the main cause of treatment failure. Positron emission tomography (PET) using hypoxia radiotracers has been studied extensively and has proven its feasibility and reproducibility to detect tumor hypoxia. A number of studies confirmed that the uptake of FMISO in the recurrent region is significantly higher than that in the non-recurrent region. The escalation of dose to hypoxic tumors may improve outcomes. The technical feasibility of optimizing radiotherapeutic plans has been well documented. To define the hypoxic tumour volume, there are two main approaches: dose painting by contour (DPBC) or by number (DPBN) based on PET images. Despite amazing technological advances, precision in target coverage, and surrounding tissue sparring, radiation oncology is still not considered a targeted treatment if the “one dose fits all” approach is used. Using FMISO and other hypoxia tracers may be an important step for individualizing radiation treatment and together with future radiomic principles and a possible genome-based adjusting dose, will move radiation oncology into the precise and personalized era.

Small Molecules and Immunotherapy Agents for Enhancing Radiotherapy in Glioblastoma

Glioblastoma (GBM) is an aggressive primary brain tumor that is associated with a poor prognosis and quality of life. The standard of care has changed minimally over the past two decades and currently consists of surgery followed by radiotherapy (RT), concomitant and adjuvant temozolomide, and tumor treating fields (TTF). Factors such as tumor hypoxia and the presence of glioma stem cells contribute to the radioresistant nature of GBM. In this review, we discuss the current treatment modalities, mechanisms of radioresistance, and studies that have evaluated promising radiosensitizers. Specifically, we highlight small molecules and immunotherapy agents that have been studied in conjunction with RT in clinical trials. Recent preclinical studies involving GBM radiosensitizers are also discussed.

Cellular mechanism of action of 2-nitroimidzoles as hypoxia-selective therapeutic agents

Solid tumours are often poorly oxygenated, which confers resistance to standard treatment modalities. Targeting hypoxic tumours requires compounds, such as nitroimidazoles (NIs), equipped with the ability to reach and become activated within diffusion limited tumour niches. NIs become selectively entrapped in hypoxic cells through bioreductive activation, and have shown promise as hypoxia directed therapeutics. However, little is known about their mechanism of action, hindering the broader clinical usage of NIs. Iodoazomycin arabinofuranoside (IAZA) and fluoroazomycin arabinofuranoside (FAZA) are clinically validated 2-NI hypoxic radiotracers with excellent tumour uptake properties. Hypoxic cancer cells have also shown preferential susceptibility to IAZA and FAZA treatment, making them ideal candidates for an in-depth study in a therapeutic setting. Using a head and neck cancer model, we show that hypoxic cells display higher sensitivity to IAZA and FAZA, where the drugs alter cell morphology, compromise DNA replication, slow down cell cycle progression and induce replication stress, ultimately leading to cytostasis. Effects of IAZA and FAZA on target cellular macromolecules (DNA, proteins and glutathione) were characterized to uncover potential mechanism(s) of action. Covalent binding of these NIs was only observed to cellular proteins, but not to DNA, under hypoxia. While protein levels remained unaffected, catalytic activities of NI target proteins, such as the glycolytic enzyme glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and the detoxification enzyme glutathione S-transferase (GST) were significantly curtailed in response to drug treatment under hypoxia. Intraperitoneal administration of IAZA was well-tolerated in mice and produced early (but transient) growth inhibition of subcutaneous mouse tumours.

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Hypoxic cells display preferential sensitivity to IAZA and FAZA.

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They alter cell morphology and induce cytostasis.

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IAZA and FAZA generate covalent adducts of proteins but not DNA.

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GAPDH and GST activities, but not protein levels, are significantly reduced.

Therapeutic Modification of Hypoxia

Regions of reduced oxygenation (hypoxia) are a characteristic feature of virtually all animal and human solid tumours. Numerous preclinical studies, both in vitro and in vivo, have shown that decreasing oxygen concentration induces resistance to radiation. Importantly, hypoxia in human tumours is a negative indicator of radiotherapy outcome. Hypoxia also contributes to resistance to other cancer therapeutics, including immunotherapy, and increases malignant progression as well as cancer cell dissemination. Consequently, substantial effort has been made to detect hypoxia in human tumours and identify realistic approaches to overcome hypoxia and improve cancer therapy outcomes. Hypoxia-targeting strategies include improving oxygen availability, sensitising hypoxic cells to radiation, preferentially killing these cells, locating the hypoxic regions in tumours and increasing the radiation dose to those areas, or applying high energy transfer radiation, which is less affected by hypoxia. Despite numerous clinical studies with each of these hypoxia-modifying approaches, many of which improved both local tumour control and overall survival, hypoxic modification has not been established in routine clinical practice. Here we review the background and significance of hypoxia, how it can be imaged clinically and focus on the various hypoxia-modifying techniques that have undergone, or are currently in, clinical evaluation.

Identification of proteins and cellular pathways targeted by 2-nitroimidazole hypoxic cytotoxins

Tumour hypoxia negatively impacts therapy outcomes and continues to be a major unsolved clinical problem. Nitroimidazoles are hypoxia selective compounds that become entrapped in hypoxic cells by forming drug-protein adducts. They are widely used as hypoxia diagnostics and have also shown promise as hypoxia-directed therapeutics. However, little is known about the protein targets of nitroimidazoles and the resulting effects of their modification on cancer cells. Here, we report the synthesis and applications of azidoazomycin arabinofuranoside (N3-AZA), a novel click-chemistry compatible 2-nitroimidazole, designed to facilitate (a) the LC-MS/MS-based proteomic analysis of 2-nitroimidazole targeted proteins in FaDu head and neck cancer cells, and (b) rapid and efficient labelling of hypoxic cells and tissues. Bioinformatic analysis revealed that many of the 62 target proteins we identified participate in key canonical pathways including glycolysis and HIF1A signaling that play critical roles in the cellular response to hypoxia. Critical cellular proteins such as the glycolytic enzyme glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and the detoxification enzyme glutathione S-transferase P (GSTP1) appeared as top hits, and N3-AZA adduct formation significantly reduced their enzymatic activities only under hypoxia. Therefore, GAPDH, GSTP1 and other proteins reported here may represent candidate targets to further enhance the potential for nitroimidazole-based cancer therapeutics.

Application of Radiosensitizers in Cancer Radiotherapy

Radiotherapy (RT) is a cancer treatment that uses high doses of radiation to kill cancer cells and shrink tumors. Although great success has been achieved on radiotherapy, there is still an intractable challenge to enhance radiation damage to tumor tissue and reduce side effects to healthy tissue. Radiosensitizers are chemicals or pharmaceutical agents that can enhance the killing effect on tumor cells by accelerating DNA damage and producing free radicals indirectly. In most cases, radiosensitizers have less effect on normal tissues. In recent years, several strategies have been exploited to develop radiosensitizers that are highly effective and have low toxicity. In this review, we first summarized the applications of radiosensitizers including small molecules, macromolecules, and nanomaterials, especially those that have been used in clinical trials. Second, the development states of radiosensitizers and the possible mechanisms to improve radiosensitizers sensibility are reviewed. Third, the challenges and prospects for clinical translation of radiosensitizers in oncotherapy are presented.

Patient-Derived Xenograft and Organoid Models for Precision Medicine Targeting of the Tumour Microenvironment in Head and Neck Cancer

Patient survival from head and neck squamous cell carcinoma (HNSCC), the seventh most common cause of cancer, has not markedly improved in recent years despite the approval of targeted therapies and immunotherapy agents. Precision medicine approaches that seek to individualise therapy through the use of predictive biomarkers and stratification strategies offer opportunities to improve therapeutic success in HNSCC. To enable precision medicine of HNSCC, an understanding of the microenvironment that influences tumour growth and response to therapy is required alongside research tools that recapitulate the features of human tumours. In this review, we highlight the importance of the tumour microenvironment in HNSCC, with a focus on tumour hypoxia, and discuss the fidelity of patient-derived xenograft and organoids for modelling human HNSCC and response to therapy. We describe the benefits of patient-derived models over alternative preclinical models and their limitations in clinical relevance and how these impact their utility in precision medicine in HNSCC for the discovery of new therapeutic agents, as well as predictive biomarkers to identify patients' most likely to respond to therapy.

Fundamentals to clinical application of nanoparticles in cancer immunotherapy and radiotherapy

Cancer immunotherapy has made rapid progress over the past decade leading to high enthusiasm and interest worldwide. Codelivery of immunomodulators with chemotherapeutic agents and radioisotopes has been shown to elicit a strong and sustained immune response in animal models. Despite showing promising results in metastatic and recurrent cancers, the utilisation of immunotherapy in clinical settings has been limited owing to uncertainties in elicited immune response and occurrence of immune-related adverse events. These uncertainties can be overcome with the help of nanoparticles possessing unique properties for the effective delivery of targeted agents to specific sites. Nanoparticles play a crucial role in the effective delivery of cancer antigens and adjuvants, modulation of tumour microenvironment, production of long-term immune response and development of cancer vaccines. Here, we provide a comprehensive summary of nanotechnology-based cancer immunotherapy and radiotherapy including basics of nanotechnology, properties of nanoparticles and various methods of employing nanoparticles in cancer treatment. Thus, nanotechnology is anticipated to overcome the limitations of existing cancer immunotherapy and to effectively combine various cancer treatment modalities.

Radioresistance in Glioblastoma and the Development of Radiosensitizers

Ionizing radiation is a common and effective therapeutic option for the treatment of glioblastoma (GBM). Unfortunately, some GBMs are relatively radioresistant and patients have worse outcomes after radiation treatment. The mechanisms underlying intrinsic radioresistance in GBM has been rigorously investigated over the past several years, but the complex interaction of the cellular molecules and signaling pathways involved in radioresistance remains incompletely defined. A clinically effective radiosensitizer that overcomes radioresistance has yet to be identified. In this review, we discuss the current status of radiation treatment in GBM, including advances in imaging techniques that have facilitated more accurate diagnosis, and the identified mechanisms of GBM radioresistance. In addition, we provide a summary of the candidate GBM radiosensitizers being investigated, including an update of subjects enrolled in clinical trials. Overall, this review highlights the importance of understanding the mechanisms of GBM radioresistance to facilitate the development of effective radiosensitizers.

Fragmentation Patterns of Radiosensitizers Metronidazole and Nimorazole upon Valence Ionization

We study gas-phase photodissociation of radiosensitizer molecules nimorazole and metronidazole with the focus on the yield of the oxygen mimics nitrogen oxides and nitrous acid. Regardless of photon energy, we find the nimorazole cation to split the intramolecular bridge with little NO₂ or NO production, which makes the molecule a precursor of dehydrogenated methylnitroimidazole. Metronidazole cation, on the contrary, has numerous fragmentation pathways with strong energy dependence. Most notably, ejection of NOOH and NO₂ takes place within 4 eV from the valence ionization energy. Whereas the NO₂ ejection is followed by further fragmentation steps when energy so allows, we find emission of NOOH takes place in microsecond time-scales and as a slow process that is relevant only when no other competing reaction is feasible. These primary dissociation characteristics of the molecules are understood by applying the long-known principle of rapid internal conversion of the initial electronic excitation energy and by studying the energy minima and the saddle points on the potential energy surface of the electronic ground state of the molecular cation.

Interstitial diffuse optical probe with spectral fitting to measure dynamic tumor hypoxia

Understanding the dynamic nature of tumor hypoxia is vital for cancer therapy. The presence of oxygen within a tumor during radiation therapy increases the likelihood of local control. We used a novel interstitial diffuse optical probe to make real-time measurements of blood volume fraction and hemoglobin oxygen saturation within a tumor at a high temporal resolution. This device was initially characterized and benchmarked using a customized vessel designed to control hemoglobin oxygen saturation and blood volume in a solution of blood with different concentrations of an oxygen scavenger, tetrakis (hydroxymethyl) phosphonium chloride. The optical device was found to consistently monitor the changes in oxygen saturation and these changes correlated to the concentration of the oxygen scavenger added. In near-simultaneous measurements of blood volume and oxygen saturation in tumor-bearing mice, the changes in blood volume fraction and oxygen saturation measured with the interstitial diffuse optical probe were benchmarked against photoacoustic imaging system to track and compare temporal dynamics of oxygen saturation and blood volume in a patient-derived xenograft model of hypopharyngeal carcinoma. Positive correlations between our device and photoacoustic imaging in measuring blood volume and oxygen saturation were observed.

Hyperthermia-triggered release of hypoxic cell radiosensitizers from temperature-sensitive liposomes improves radiotherapy efficacy in vitro

Hypoxia is a characteristic feature of solid tumors and an important cause of resistance to radiotherapy. Hypoxic cell radiosensitizers have been shown to increase radiotherapy efficacy, but dose-limiting side effects prevent their widespread use in the clinic. We propose the encapsulation of hypoxic cell radiosensitizers in temperature-sensitive liposomes (TSL) to target the radiosensitizers specifically to tumors and to avoid unwanted accumulation in healthy tissues. The main objective of the present study is to develop and characterize TSL loaded with the radiosensitizer pimonidazole (PMZ) and to evaluate the in vitro efficacy of free PMZ and PMZ encapsulated in TSL in combination with hyperthermia and radiotherapy. PMZ was actively loaded into TSL at different drug/lipid ratios, and the physicochemical characteristics and the stability of the resulting TSL-PMZ were evaluated. PMZ release was determined at 37 °C and 42 °C in HEPES buffer saline and fetal bovine serum. The concentration-dependent radiosensitizing effect of PMZ was investigated by exposing FaDu cells to different PMZ concentrations under hypoxic conditions followed by exposure to ionizing irradiation. The efficacy of TSL-PMZ in combination with hyperthermia and radiotherapy was determined in vitro, assessing cell survival and DNA damage by means of the clonogenic assay and histone H2AX phosphorylation, respectively. All TSL-PMZ formulations showed high encapsulation efficiencies and were stable for 30 d upon storage at 4 °C and 20 °C. Fast PMZ release was observed at 42 °C, regardless of the drug/lipid ratio. Increasing the PMZ concentration significantly enhanced the effect of ionizing irradiation. Pre-heated TSL-PMZ in combination with radiotherapy caused a 14.3-fold increase in cell death as compared to radiotherapy treatment alone. In conclusion, our results indicate that TSL-PMZ in combination with hyperthermia can assist in improving the efficacy of radiotherapy under hypoxic conditions.

Controlling NO Production Upon Valence Ionization of Nitroimidazoles

Nitroimidazole exhibits a remarkable regioselective fragmentation subsequent to valence ionization, which is characterized by ejection of NO. As NO is also considered to be an effective radiosensitizer, we investigated its production efficiency as a function of isomeric composition (the site of the NO₂ nitro group). We observe strong dependence in the 8.6-15 eV binding energy range, and moreover, that the production of NO can be effectively suppressed by methylation of nitroimidazole. This behavior can be understood by modification of the valence electronic structure with respect to the dissociation threshold, which gives rise to varying effective density of dissociative states. We find the NO yield to follow the efficiency of the nitroimidazole dervivatives as radiosensitizers, found in preclinical studies.

Hypoxia-targeted drug delivery

Hypoxia is a state of low oxygen tension found in numerous solid tumours. It is typically associated with abnormal vasculature, which results in a reduced supply of oxygen and nutrients, as well as impaired delivery of drugs. The hypoxic nature of tumours often leads to the development of localized heterogeneous environments characterized by variable oxygen concentrations, relatively low pH, and increased levels of reactive oxygen species (ROS). The hypoxic heterogeneity promotes tumour invasiveness, metastasis, angiogenesis, and an increase in multidrug-resistant proteins. These factors decrease the therapeutic efficacy of anticancer drugs and can provide a barrier to advancing drug leads beyond the early stages of preclinical development. This review highlights various hypoxia-targeted and activated design strategies for the formulation of drugs or prodrugs and their mechanism of action for tumour diagnosis and treatment.

EPOETIN A ALFA IN RADIOTERAPIA

Sixty per cent of oncologic patients need radiation therapy for cure or palliation. In fact, in most neoplastic diseases, a better local control positively impacts on disease-free survival and overall survival. The efficacy of radiotherapy depends on several factors: while some are tumor-related, others are host-related.

Radiobiological phenomena are also important: ionizing radiation is responsible for cell damage (double rupture of DNA chains), mostly an indirect mechanism with the formation of free radicals. Their toxic action is enhanced by the oxygen partial pressure at the cellular level.

A number of studies have confirmed that good tissue oxygenation is a function of a high hemoglobin level in the peripheral blood (Hb≥13g/dL). Unfortunately, these values are rarely present in oncologic patients due to the disease-related toxicosis as well as to the therapy induced hematologic toxicity.

The treatment of anemia is free of risk for the recent developments in technology which with gene cloning and the technique of recombinant DNA has allowed the production of human recombinant erythropoietin.

Erythropoietin is produced by the interstitial cells of renal tubules in response to hypoxia. It prevents apoptosis and promotes erythroid proliferation and differentiation with consequent reticulocyte release and hemoglobin synthesis.

It is not completely understood whether the efficacy of radiotherapy depends on hemoglobin values present at the start of irradiation (often less than 12-13 g/dL) or on the higher ones observed during and at the end of radiotherapy.

Therefore, preventive systemic erythropoietin therapy in non anemic patients in terms of costs/benefits is at present non sustainable.

To the contrary, in patients undergoing radiotherapy to extended fields or aggressive multimodal treatments, for the higher risk of anemia, the early use of this treatment can be hypothesized in case of initial anemia to improve therapy compliance and prevent negative conditioning of results.

Keeping in mind that grade 1 minimum toxicity for red cells, according to the Radiation Therapy Oncology Group (RTOG) is equal to 11gHb/dL we think that this value can be considered as cutoff to start erythropoietin therapy.

DAHANCA 10 - Effect of darbepoetin alfa and radiotherapy in the treatment of squamous cell carcinoma of the head and neck. A multicenter, open-label, randomized, phase 3 trial by the Danish head and neck cancer group

PURPOSE

To evaluate if correction of low hemoglobin (Hb) levels by means of darbepoetin alfa improves the outcomes of radiotherapy in patients with squamous cell carcinoma of the head and neck (HNSCC).

PATIENTS AND METHODS

Patients eligible for primary radiotherapy and who had Hb values below 14.0 g/dl were randomized to receive accelerated fractionated radiotherapy with or without darbepoetin alfa. Patients also received the hypoxic radiosensitizer nimorazole. Darbepoetin alfa was given weekly during radiotherapy or until the Hb value exceeded 15.5 g/dl.

RESULTS

Following a planned interim analysis which showed inferiority of the experimental treatment the trial was stopped after inclusion of 522 patients (of a planned intake of 600). Of these, 513 were eligible for analysis (254 patients treated with darbepoetin alfa and 259 patients in the control group). Overall, the patients were distributed according to the stratification parameters (gender, T and N staging, tumor site). Treatment with darbepoetin alfa increased the Hb level to the planned value in 81% of the patients. The compliance was good without excess serious adverse events. The results showed a poorer outcome with a 5-year cumulative loco-regional failure rate of 47% vs. 34%, Hazard Ratio (HR): 1.53 [1.16-2.02], for the darbepoetin alfa vs. control arm, respectively. This was also seen for the endpoints of event-free survival (HR: 1.36 [1.09-1.69]), disease-specific death (HR: 1.43 [1.08-1.90]), and overall survival (HR: 1.30 [1.02-1.64]). There was no enhanced risk of cardio-vascular events observed in the experimental arm or any significant differences in acute or late radiation related morbidity. All univariate analyses were confirmed in a multivariate setting.

CONCLUSION

Correction of the Hb level with darbepoetin alfa during radiotherapy of patients with HNSCC resulted in a significantly poorer tumor control and survival.

Cancer Radiosensitizers

Radiotherapy (RT) is a mainstay treatment for many types of cancer, although it is still a large challenge to enhance radiation damage to tumor tissue and reduce side effects to healthy tissue. Radiosensitizers are promising agents that enhance injury to tumor tissue by accelerating DNA damage and producing free radicals. Several strategies have been exploited to develop highly effective and low-toxicity radiosensitizers. In this review, we highlight recent progress on radiosensitizers, including small molecules, macromolecules, and nanomaterials. First, small molecules are reviewed based on free radicals, pseudosubstrates, and other mechanisms. Second, nanomaterials, such as nanometallic materials, especially gold-based materials that have flexible surface engineering and favorable kinetic properties, have emerged as promising radiosensitizers. Finally, emerging macromolecules have shown significant advantages in RT because these molecules can be combined with biological therapy as well as drug delivery. Further research on the mechanisms of radioresistance and multidisciplinary approaches will accelerate the development of radiosensitizers.

Fragmentation patterns of 4(5)-nitroimidazole and 1-methyl-5-nitroimidazole-The effect of the methylation

We present here the photofragmentation patterns of doubly ionized 4(5)-nitroimidazole and 1-methyl-5-nitroimidazole. The doubly ionized state was created by core ionizing the C 1s orbitals of the samples, rapidly followed by Auger decay. Due to the recent development of nitroimidazole-based radiosensitizing drugs, core ionization was selected as it represents the very same processes taking place under the irradiation with medical X-rays. In addition to the fragmentation patterns of the sample, we study the effects of methylation on the fragmentation patterns of nitroimidazoles. We found that methylation alters the fragmentation significantly, especially the charge distribution between the final fragments. The most characteristic feature of the methylation is that it effectively quenches the production of NO and NO⁺ , widely regarded as key radicals in the chemistry of radiosensitization by the nitroimidazoles.

Biomarker driven treatment of head and neck squamous cell cancer

Abstract

Treatment modalities of head and neck squamous cell cancer include surgery, radiation, chemotherapy, targeted agents and immune checkpoint inhibition. Treatment is often toxic and can affect long-term function and quality of life. In this context, identification of biomarker data that can help tailor therapy on an individualized basis and reduce treatment-related toxicity would be highly beneficial. A variety of predictive biomarkers have been discovered and are already utilized in clinical practice, while many more are being explored. We will review p16 overexpression as a surrogate biomarker in HPV-associated head and neck cancer and plasma EBV DNA as a biomarker in nasopharyngeal carcinoma, the two established biomarkers currently utilized in clinical practice. We will also examine novel predictive biomarkers that are in clinical development and may shape the future landscape of targeted head and neck cancer therapy. These emerging biomarkers include the tyrosine kinases and their signaling pathway, immune checkpoint biomarkers, tumor suppressor abnormalities, and molecular predictors of hypoxia-targeted therapy. We will also look at futuristic biomarkers including detection of circulating DNA from clinical specimens and rapid tumor profiling. We will highlight the ongoing effort that will see a shift from prognostic to predictive biomarker development in head and neck cancer with the goal of delivering individualized cancer therapy.

Trial registration

N/A.

The impact of hypoxia and its modification of the outcome of radiotherapy

Since the initial observations made at the beginning of the last century, it has been established that solid tumors contain regions of low oxygenation (hypoxia). Tumor cells can survive in these hypoxic conditions and are a major factor in tumor radioresistance. This significance has resulted in hypoxia becoming the most cited biological topic in translational radiation oncology. Identifying hypoxic cells in human tumors has become paramount, and the ability to do this has been improved by the help of new imaging techniques and the use of predictive gene profiles. Substantial data confirm the presence of hypoxia in many types of human tumors, although with considerable heterogeneity among individual tumors. Various approaches have been investigated for eliminating the hypoxic population. These include increasing oxygen availability, directly radiosensitizing or killing the hypoxic cells, indirectly affecting them by targeting the tumor vascular supply, increasing the radiation dose to this resistant population, or by using radiation with a high linear energy transfer, for which hypoxia is believed to be less of an issue. Many of these approaches have undergone controlled clinical trials during the last 50 years, and the results have shown that hypoxic radiation resistance can indeed be overcome. Thus, ample data exists to support a high level of evidence for the benefit of hypoxic modification. However, such hypoxic modification still has no impact on general clinical practice. In this review we summarize the biological rationale, and the current activities and trials, related to identifying and overcoming hypoxia in modern radiotherapy.

Molecular Pathways: A Novel Approach to Targeting Hypoxia and Improving Radiotherapy Efficacy via Reduction in Oxygen Demand

Tumor hypoxia presents a unique therapeutic challenge in the treatment of solid malignancies. Its presence has been established to be a poor prognostic factor in multiple cancer types, and past hypoxia-directed approaches have yielded generally disappointing results. Previous approaches have centered on either increasing oxygen delivery or administering agents that preferentially radiosensitize or kill hypoxic cells. However, a novel and potentially more effective method may be to increase therapeutic benefit by decreasing tumor oxygen consumption via agents such as metformin or nelfinavir in a patient population that is enriched for tumor hypoxia. This promising approach is currently being investigated in clinical trials and the subject of this article.

Incidence of and survival after glottic squamous cell carcinoma in Denmark from 1971 to 2011-A report from the Danish Head and Neck Cancer Group

AIM

To describe the incidence, disease-specific mortality (DSM), and overall survival (OS) of patients with glottic squamous cell carcinomas (SCC) in Denmark from 1971-2011 in a national population-based cohort of consecutive patients.

MATERIALS AND METHODS

All patients diagnosed with glottic SCC stage I-IV between 1971 and 2011 in Denmark were included. Patients were identified from the Danish Head and Neck Cancer database, which has a coverage of approximately 100% of registered glottic cancer in Denmark. Information on vital status and cause of death were updated using patient charts and national registries.

RESULTS

In total 5132 patients with glottic SCC were included. The yearly number of new cases increased from 107 in the 1970s to 139 in the 2000s. Overall, the incidence increased from 1.9 to 2.6 per 100,000, with a more prominent increase in men (3.5 to 4.7) compared with women (0.4 to 0.6). The 5-year DSM was 16% (15-17%) and the 5-year OS was 63% (61-64). The hazard rate of DSM adjusted for patient characteristics, tumour characteristics and waiting-time was significantly lower in the 2000s (p < 0.01), and the hazard rate of OS was significantly higher (p < 0.01) compared to the earlier decades. Longer waiting-time for treatment (>25 d) significantly increased DSM and reduced OS.

CONCLUSION

Despite being highly avoidable with smoking cessation, the incidence of glottic SCC increased in Denmark from 1971-2011. The adjusted hazard rate of DSM and overall death after glottic SCC was significantly lower in the 2000s compared to previous decades. Waiting-time for treatment significantly influenced DSM and OS.

Pattern of failure in 5001 patients treated for glottic squamous cell carcinoma with curative intent - A population based study from the DAHANCA group

PURPOSE

To describe the pattern of failure in a national consecutive cohort of patients with glottic squamous cell carcinomas (SCC) treated with primary radiotherapy (RT) with curative intent over a 41-year period.

MATERIALS AND METHODS

All patients undergoing curative treatment for a glottic SCC diagnosed in Denmark between 1971 and 2011 were included and followed from the first contact with the oncology center to death or February 15, 2015.

RESULTS

5001 patients were identified of whom 98% had primary RT. The median follow-up was 9.1 years/5.7 years (patients alive/patients who died). Ten patients were lost to follow-up. In total 1511 failures were observed; of these 93%, 11% and 5% included T site, N site, and M site, respectively. For patients diagnosed in the 70s and the 00s, respectively, the five-year incidences were: local failure (32% vs 19%), loco-regional failure (34% vs 21%), laryngectomy (26% vs 10%), laryngectomy-free survival (48% vs 62%), disease-free survival (62% vs 68%), and overall survival (62% vs 68%). The five-year incidence of ultimate failure (13-16%) remained statistically unchanged.

CONCLUSION

From the 70s to the 00s a continually improving primary disease-control was observed with a concurrent decrease in the incidence of laryngectomy. The survival rate was significantly higher in the 00s compared to the previous three decades.

The DAHANCA 6 randomized trial: Effect of 6 vs 5 weekly fractions of radiotherapy in patients with glottic squamous cell carcinoma

PURPOSE

The DAHANCA 6 trial evaluated tumor response and morbidity after moderate accelerated radiotherapy compared to conventional fractionated radiotherapy in patients treated for glottic squamous cell carcinoma (SCC). Further, the failure pattern and incidence of new primary tumors were explored.

PATIENTS AND METHODS

Six hundred and ninety-four patients with non-metastatic glottic SCC were randomized between six or five weekly fractions (fx/w) of radiotherapy to the same total dose. The median treatment time was 38 and 46days, respectively. The primary endpoint was loco-regional failure.

RESULTS

Median follow-up time was 14.5years. Of the 177 failures, 167 involved T-site. The cumulative incidence of loco-regional failure (LRF) was 21.6% in the 6fx/w group and 29.3% in the 5fx/w group and the corresponding hazard rate (HR) of LRF was 0.72 (CI: 0.53-0.97, p=0.04). The effect of acceleration on LRF was especially evident in well differentiated tumors (HR=0.42 (CI: 0.23-0.75) and in T1-2 tumors (HR=0.60 (CI: 0.41-0.89)). The HR of laryngectomy was 0.72 (CI: 0.50-1.04) in the 6fx/w group compared to the 5fx/w group. The hazards of disease-specific death, event-free survival, and overall survival were comparable between the two groups. Significantly more patients experienced severe acute mucositis in the 6fx/w group but the incidence of late morbidity was comparable between the groups. New primary tumors occurred in 22.5% of the patients.

CONCLUSION

Moderate accelerated radiotherapy significantly improved loco-regional control in patients with glottic SCC.

Locally advanced head and neck cancer treated with accelerated radiotherapy, the hypoxic modifier nimorazole and weekly cisplatin. Results from the DAHANCA 18 phase II study

PURPOSE/OBJECTIVE

A phase II clinical trial evaluating the feasibility and outcome of treating locally advanced head and neck squamous cell carcinoma (HNSCC) with accelerated radiotherapy, the hypoxic modifier nimorazole and weekly cisplatin.

MATERIAL AND METHODS

A total of 227 patients with stage III or IV HNSCC of the larynx, oropharynx, hypopharynx, or oral cavity where included between January 2007 and December 2010. The prescribed radiotherapy (RT) dose was 66-68 Gy in 2 Gy fractions, 6 F/W. The hypoxic radiosensitiser nimorazole was given orally at a dose of 1200 mg/m(2) before each fraction. Concomitant cisplatin (40 mg/m(2)) i.v. was given once a week for a maximum of six cycles. Outcome data were evaluated in terms of loco-regional tumour control (LRC), event-free survival (EFS) and overall survival (OS). Morbidity data were evaluated based on the DAHANCA routine registration. Human papillomavirus (HPV)-status was estimated by immunohistochemical staining of p16.

RESULTS

Included were 178 (78%) men and 49 (22%) women with a median age of 57 years. All except five patients received RT as prescribed. At least five series of cisplatin was given to 164 (72%) of the patients, and 149 patients (66%) received the full dose of nimorazole. The five-year actuarial LRC, EFS and OS rates were 80%, 67% and 72%, respectively. The LRC rates according to site were: oropharynx: 88%, larynx: 77%, hypopharynx 72% and oral cavity 49%, respectively. HPV/p16 staining was obtained in 141 of the 150 oropharyngeal cancers. Of these, 112 (79%) were p16 pos and 29 (21%) were p16 neg. LRC for the p16 neg oropharyngeal cancers was poorer than for the p16 pos (74% vs. 91%; p = 0.02). Tube feeding during treatment was necessary for 146 (64%) patients. At 12 months this number was reduced to 6%.

CONCLUSION

The treatment was tolerable in this cohort of locally advanced HNSCC patients. Acute and late toxicity was comparable to similar studies of chemoradiotherapy, and the outcome superior to the data reported in the literature. This strongly indicates that RT of advanced head and neck cancer must include as well hypoxic modification, accelerated fractionation as chemoradiotherapy to yield optimal outcome.

Drug radiotherapy combinations: review of previous failures and reasons for future optimism

Combining chemotherapy with radiotherapy has resulted in significant clinical improvements in many different tumour types. However, the non-specific mechanisms by which these drugs exert their effects mean that this is often at the expense of increased side effects. Previous attempts at using targeted drugs to induce more tumour specific radiosensitisation have been generally disappointing. Although cetuximab, an EGFR monoclonal antibody, resulted in improved overall survival in HNSCC when combined with radiotherapy, it has failed to show benefit when added to chemo-radiotherapy. In addition, our inability to successfully use drug treatments to reverse tumour hypoxia is underlined by the fact that no such treatment is currently in widespread clinical use. The reasons for these failures include the lack of robust biomarkers, and the previous use of drugs with unacceptable side-effect profiles. Despite these disappointments, there is reason for optimism. Our improved understanding of key signal transduction pathways and of tumour specific DNA repair deficiencies has produced new opportunities to specifically radiosensitise tumours. Novel strategies to reduce tumour hypoxia include the use of drugs that cause vascular normalisation and drugs that reduce tumour oxygen consumption. These new strategies, combined with better compounds at our disposal, and an ability to learn from our previous mistakes, mean that there is great promise for future drug-radiotherapy combinations to result in significant clinical benefits.

Compliance and toxicity of the hypoxic radiosensitizer nimorazole in the treatment of patients with head and neck squamous cell carcinoma (HNSCC)

PURPOSE

To evaluate the compliance and toxicity of the hypoxic radiosensitizer nimorazole in head and neck cancer patients.

METHODS

A retrospective study of patients with head and neck squamous cell carcinoma (HNSCC), treated in Denmark between 1990 and 2013. All patients treated with radical radiotherapy (± chemotherapy) [66-70 Gy; 33-35 fractions; 2 Gy/fraction; 5-6 fractions/week] concomitant with the hypoxic radiosensitizer nimorazole. Nimorazole was administered as oral tablets in doses of approximately 1.2 g/m(2) body surface area in connection with the first of each daily radiation treatment. A second daily dose of 1 g was given in connection with the second radiotherapy fraction in the accelerated fractionation regimen. The compliance was estimated as the percentage of the initially prescribed dose, which was received by each patient. The main side effects were recorded.

RESULTS

A total of 1049 patients were investigated. The tolerance to nimorazole was fair: 58% of patients received the full prescribed total dose. Nausea and vomiting were the major complaints: among the 260 patients with dose reductions due to known side effects, (87%) were due to nausea/vomiting. All side effects ceased when treatment was interrupted, and neither severe nor long lasting side effects were observed. Female patients were significantly more likely to have dose reduction (OR 2.02; 95% CI 1.50-2.70), and nausea/vomiting. Patients aged more than 70 years were significantly more likely to have dose reduction. Patients who received less than 1100 mg/m(2) were significantly less likely to have dose reduction (OR 0.58; CI 0.44-0.78), and nausea/vomiting, compared to those who received 1100-1300 mg/m(2). The tolerance was also less in the group of patients received accelerated chemoradiotherapy (OR 1.70; CI 1.20-2.50) with more association with nausea/vomiting (OR 2.09; CI 1.40-3.10).

CONCLUSION

The compliance to nimorazole is fair, with tolerable acute, but neither persistent nor late, toxicity. It can be administered with chemotherapy and different radiotherapy fractionation schedules.

Radiotherapeutic management of locally advanced head and neck cancer

Head and neck cancer management has undergone several paradigm shifts for several relevant reasons. From the dismal experience with the use of radiotherapy as the sole modality in the treatment of this group of patients with advanced disease, radiotherapy has been evaluated as an adjuvant for the same group of patients who had undergone successful surgery. Although there is no level 1 evidence to support postoperative adjuvant radiation, several studies have demonstrated that adjuvant radiotherapy reduces the local failures and, thereby, improves survival. Predictors of recurrence after surgical resection are: positive margins of resection; extranodal spread in involved nodes; perineural invasion; and presence of two or more involved regional lymph nodes. Realization of the advantages of a combination of chemotherapy with radiotherapy has had a major impact on the management of these cancers. There is emerging evidence for the use of adjuvant concurrent chemoradiotherapy in the group with high-risk features. Multiple organ conservation strategies in the management of locally advanced head and neck cancers have evolved over the years. However, the meta-analyses of impact of chemotherapy in various settings reveal that concomitant chemoradiotherapy is superior to any of the other regimens. Increasing use of computed tomography, magnetic resonance imaging and positron emission tomography scan images has resulted in better visualization of target volumes and critical structures. Delineation of these structures is of paramount importance and has resulted in a profound change in conformal treatment planning. Better understanding of the physical aspects of delivery of radiotherapy and the advent of modern treatment planning systems have led to the development of conformal techniques. Although the benefit of these techniques on survival have yet to be demonstrated, there is evidence to suggest that they reduce treatment-related toxicities significantly and facilitate dose escalation. Increased knowledge of radiobiology has led to the development of various altered fractionation regimens in the management of locally advanced head and neck cancers. Discovery of cell-cycle kinetics and signal transduction pathways has led to the unearthing of several potential targets for targeted therapy. The epidermal growth factor receptor gene has emerged as the most promising target. The role of biological radiation response modifiers is evolving. All of these approaches to improve the therapeutic gain would be incomplete without evaluating their effect on the quality of life of these patients.

The prospective application of a hypoxic radiosensitizer, doranidazole to rat intracranial glioblastoma with blood brain barrier disruption

Background

Glioblastoma is one of the intractable cancers and is highly resistant to ionizing radiation. This radioresistance is partly due to the presence of a hypoxic region which is widely found in advanced malignant gliomas. In the present study, we evaluated the effectiveness of the hypoxic cell sensitizer doranidazole (PR-350) using the C6 rat glioblastoma model, focusing on the status of blood brain barrier (BBB).

Methods

Reproductive cell death in the rat C6 glioma cell line was determined by means of clonogenic assay. An intracranial C6 glioma model was established for the in vivo experiments. To investigate the status of the BBB in C6 glioma bearing brain, we performed the Evans blue extravasation test. Autoradiography with [¹⁴C]-doranidazole was performed to examine the distribution of doranidazole in the glioma tumor. T2-weighted MRI was employed to examine the effects of X-irradiation and/or doranidazole on tumor growth.

Results

Doranidazole significantly enhanced radiation-induced reproductive cell death in vitro under hypoxia, but not under normoxia. The BBB in C6-bearing brain was completely disrupted and [¹⁴C]-doranidazole specifically penetrated the tumor regions. Combined treatment with X-irradiation and doranidazole significantly inhibited the growth of C6 gliomas.

Conclusions

Our results revealed that BBB disruption in glioma enables BBB-impermeable radiosensitizers to penetrate and distribute in the target region. This study is the first to propose that in malignant glioma the administration of hydrophilic hypoxic radiosensitizers could be a potent strategy for improving the clinical outcome of radiotherapy without side effects.

In vitro hypoxic cytotoxicity and hypoxic radiosensitization. Efficacy of the novel 2-nitroimidazole N,N,N-tris[2-(2-nitro-1H-imidazol-1-yl)ethyl]amine

BACKGROUND AND PURPOSE

Tumor hypoxia is a major problem in radiation therapy of solid tumors because of the radiosensitizing effect of oxygen. Nitroimidazole-containing compounds are oxygen mimetics accumulating in hypoxic tumor areas. However, the broad use of 2-nitroimidazoles as a hypoxic radiosensitizer is limited by their partially low efficacy and/or high neurotoxicity.

MATERIALS AND METHODS

Here, we characterized the in vitro hypoxic cytotoxicity and hypoxic radiosensitizing efficacy of N,N,N-tris [2-(2-nitro-1H-imidazol-1-yl)ethyl]amine (PRC) in a hypoxia-sensitive lymphoma and a hypoxia-resistant glioblastoma cell line by colony formation assay and flow cytometry.

RESULTS

PRC exerted high hypoxic cytotoxic and radiosensitizing action on both cell lines at almost absent toxicity under normoxic conditions. In particular, under hypoxia, but not normoxia, PRC targeted the mitochondria resulting in oxidative stress, G(2)/M cell cycle arrest, and triggering of the intrinsic apoptosis pathway.

CONCLUSION

Our in vitro findings suggest that PRC might be a promising new 2-nitroimidazole for improving radiation therapy of hypoxic tumors in vivo.

Prevalence and significance of anaemia in patients receiving long-course neoadjuvant chemoradiotherapy for rectal carcinoma

AIM

The study aimed to assess the prevalence and significance of anaemia during long-course neoadjuvant radiotherapy for rectal cancer at our centre.

METHOD

Hospital coding and a prospective oncology database were used to identify all patients undergoing long-course neoadjuvant radiotherapy for rectal cancer at our centre between 2004 and 2009. A retrospective review of computerized records was used to extract individual patient data. Anaemia was defined as a haemoglobin level of < 11.5 g/dl for women and of < 13 g/dl for men. Downstaging was assessed by comparing radiological stage (rTNM) with histological stage (ypTNM). Tumour regression after radiotherapy was assessed using the Rectal Cancer Regression Group (RCRG) scores of 1-3. The results were analysed using Gnu PSPP statistical software.

RESULTS

There were 70 patients (51 men) of median age 66 (interquartile range 60-72.75) years. Of these, 24 were anaemic. Two (3%) had no haemoglobin level recorded and were excluded. Forty-two per cent of anaemic patients demonstrated mural (T) downstaging compared with 68% of nonanaemic patients (P = 0.03). There was no difference in nodal downstaging between the groups. The RCRG scores showed more tumour regression in nonanaemic patients than in anaemic patients, as follows: RCRG 1, 59%vs 30%; RCRG 2, 11%vs 17%; and RCRG 3, 38%vs 46% (P < 0.001).

CONCLUSION

The prevalence of anaemia in patients undergoing long-course neoadjuvant radiotherapy was 35%. Anaemia during long-course neoadjuvant radiotherapy was associated with significant reductions in tumour downstaging and regression.

Early response and local control of stage I non-small-cell lung cancer after stereotactic radiotherapy: difference by histology

To investigate the possible influences of various factors on tumor response to radiation, regression speeds and long-term local control rates of primary adenocarcinoma and squamous cell carcinoma of the lung after stereotactic body radiotherapy were evaluated. Ninety-one patients (65 men and 26 women) with a median age of 76 years were serially examined using computed tomography at 2, 4 and 6 months after treatment. Tumor histology was adenocarcinoma in 62 patients and squamous cell carcinoma in 29 patients. The prescribed dose was 48 Gy in four fractions given twice a week for T1 tumors (≤ 3 cm) and 52 Gy in four fractions given twice a week for T2 tumors (3-5 cm). Tumor shrinkage speed and 3-year local control rates were similar between T1 and T2 tumors and between patients with normal pulmonary function and those with impaired function. Squamous cell carcinomas shrank faster than adenocarcinomas at 2 and 4 months after radiation, but mean relative tumor size at 6 months and local control rates at 3 years did not differ significantly between the two histologies. Tumors in patients with a higher hemoglobin level tended to shrink faster but the control rates were not different. It is concluded that, although squamous cell carcinoma shrinks faster than adenocarcinoma, the two types of lung cancer are of similar radiosensitivity in terms of long-term control rates. Radiosensitivity should not be evaluated by early tumor response.

Hypoxia in head and neck squamous cell carcinoma

Hypoxia is a common feature in most of the solid tumors including head and neck squamous cell carcinoma (HNSCC). Hypoxia reflects the imbalance between oxygen consumption by the rapidly proliferating cancer cells and the insufficient oxygen delivery due to poor vascularization and blood supply. The hypoxic microenvironment in the HNSCC contributes to the development of aggressive carcinoma phenotype with high metastatic rate, resistance to therapeutic agents, and higher tumor recurrence rates, leading to low therapeutic efficiency and poor outcome. To overcome the therapeutic resistance due to hypoxia and improving the prognosis of the HNSCC patients, many approaches have been examined in laboratory studies and clinical trials. In this short paper, we discuss the mechanisms involved in the resistance of radiotherapy and chemotherapy in hypoxic condition. We also exploit the molecular mechanisms employed by the HNSCC cells to adapt the hypoxic condition and their tumorigenic role in head and neck, as well as the strategies to overcome hypoxia-induced therapeutic resistance.

Regression curves of brain metastases after gamma knife irradiation: Difference by tumor and patient characteristics

Regression curves and local control rates of brain metastases after gamma knife treatment were evaluated to investigate differences in tumor response to radiation. A total of 203 metastases were serially evaluated using contrast-enhanced MRI (or computed tomography) at 1, 2, 3, 4.5 and 6 months after a 20-Gy dose. Differences were evaluated in regression curves and control rates between tumors ≥10 mm and tumors <10 mm in mean diameter, among three major histological subtypes of lung cancer, among adenocarcinomas of the lung, breast and colorectum, and between tumors in patients with above and below median hemoglobin levels. Smaller tumors shrank faster and yielded better control rates than larger tumors. Metastases from small cell and squamous cell carcinomas of the lung shrank faster than those from lung adenocarcinoma, but 6-month control rates were not different. Breast adenocarcinomas tended to shrink faster than lung adenocarcinomas, but the control rates were not different among adenocarcinomas of the lung, breast and colorectum. Tumors in patients with higher hemoglobin levels tended to shrink faster but the control rates were not different. Small cell and squamous cell carcinomas of the lung regress more rapidly than adenocarcinomas, although local control rates might not differ significantly.

Clinically relevant biomarkers in targeted radiotherapy

Three classic parameters have been recognized as predictors or biomarkers of radiation response: intrinsic radiosensitivity, degree of hypoxia and repopulation capacity of clonogenic cells during a course of fractionated radiation therapy. Although good functional assays exist to measure these tumor parameters, and their use has led to the understanding of factors affecting outcome after radiotherapy, their application in clinical practice is hampered by technical difficulties, the length of time needed to obtain results and the lack of prospective randomized clinical trials. Recently, with the progress in molecular biology, genome-wide screening methods have been used to look for genetic signatures that can distinguish between good and bad outcome after radiotherapy. One of the most promising candidates is the epidermal growth factor receptor which is overexpressed or mutated in a variety of malignancies, such lung and head and neck cancer. Inhibition of this receptor has led to radio-sensitization with the prolongation of median survival in several cancers. Since there is significant variability in the response of patients with the same disease to radiotherapy, it would be very valuable to be able to predict which patients would benefit from a molecularly targeted therapy administered with concomitant radiation in order to increase the response rate (and cure rate) of those patients with radioresistant tumors. Optimally, this assay should be able to provide results in an efficient and reproducible manner and detect tumor genetic mutations that would provide specificity to the intervention. One approach currently in clinical practice to overcome intrinsic radioresistance and repopulation is stereotactic body radiotherapy coupled with image-guided radiation, a highly precise and powerful form of radiation, allowing radiation oncologist to treat tumors with more aggressive biological doses of radiation without causing serious normal tissues injury.

Cobalt complexes with tripodal ligands: implications for the design of drug chaperones

Extensive research is currently being conducted into metal complexes that can selectively deliver cytotoxins to hypoxic regions in tumours. The development of pharmacologically suitable agents requires an understanding of appropriate ligand-metal systems for chaperoning cytotoxins. In this study, cobalt complexes with tripodal tren (tris-(2-aminoethyl)amine) and tpa (tris-(2-pyridylmethyl)amine) ligands were prepared with ancillary hydroxamic acid, β-diketone and catechol ligands and several parameters, including: pK(a), reduction potential and cytotoxicity were investigated. Fluorescence studies demonstrated that only tpa complexes with β-diketones showed any reduction by ascorbate in situ and similarly, cellular cytotoxicity results demonstrated that ligation to cobalt masked the cytotoxicity of the ancillary groups in all complexes except the tpa diketone derivative [Co(naac)tpa](ClO(4))(2) (naac = 1-methyl-3-(2-naphthyl)propane-1,3-dione). Additionally, it was shown that the hydroxamic acid complexes could be isolated in both the hydroxamate and hydroximate form and the pK(a) values (5.3-8.5) reveal that the reversible protonation/deprotonation of the complexes occurs at physiologically relevant pHs. These results have clear implications for the future design of prodrugs using cobalt moieties as chaperones, providing a basis for the design of cobalt complexes that are both more readily reduced and more readily taken up by cells in hypoxic and acidic environments.

Clinical relevance of a new pre-treatment laboratory prognostic index in patients with oral squamous cell carcinoma

The purpose of this retrospective study was to develop a pre-treatment laboratory prognostic index (LPI) based on laboratory results that might serve as an extension to clinicopathological parameters for prognosis and treatment in patients with oral squamous cell carcinoma (OSCC). Pre-treatment LPI was calculated from C-reactive protein (CRP), hemoglobin (Hb) levels, and count of white blood cells (WBCs) due to significant (P < 0.05) association with locoregional recurrence measured for each parameter by receiver operating characteristic (ROC) curves in 187 patients with OSCC. Positive predictive values (+PV, precision rate) and negative predictive values (-PV) of LPI were measured. Likelihood ratios (LRs) were used to assess how good the pre-treatment LPI diagnostic test is to determine locoregional recurrence of the disease. CRP expression by cancer cells was confirmed by immunocytochemistry and FACS analysis. ROC analysis determined cutoff values for CRP levels, Hb levels, and WBC count and showed significant differences between nonrecurrent and recurrent group of OSCC. On univariate analysis, patients with high pre-treatment LPI (LPI ≥ 2, hazard ratio (HR) = 3.8670, 95% confidence interval (CI) = 2.2518-6.6407, P < 0.0001) had a significant poorer prognosis. Multivariate analysis showed that the most important independent prognostic factor was high pre-treatment LPI (LPI ≥ 2, HR = 3.6450, 95% CI = 2.3964-5.5441, P < 0.0001). Moreover, pre-treatment LPI ≥ 2 showed high probability that locoregional recurrence will be present later (+PV, LPI ≥ 2, 86.4%, 95% CI = 65.1-97.1). High +LR gave an excellent indication for a good quality of the test (LR+, LPI ≥ 2, 12.77, 95% CI = 8.8-18.6). Immunohistochemistry and FACS analysis confirmed inflammatory CRP expression by cancer cells. This study highlights the combination of inflammatory CRP levels, Hb levels, and WBC count as the most important independent prognostic factor in predicting disease recurrence of patients with OSCC. LPI can be used as a pre-treatment inflammatory biomarker that may identify OSCC with a more aggressive biological phenotype of the disease and might be helpful for guiding further post-operative treatment in OSCC.

Hypoxic modification of radiotherapy in squamous cell carcinoma of the head and neck--a systematic review and meta-analysis

BACKGROUND

The importance of tumour hypoxia for the outcome of radiotherapy has been under investigation for decades. Numerous clinical trials modifying the hypoxic radioresistance in squamous cell carcinoma of the head and neck (HNSCC) have been conducted, but most have been inconclusive, partly due to a small number of patients in the individual trial. The present meta-analysis was, therefore, performed utilising the results from all clinical trials addressing the specific question of hypoxic modification in HNSCC undergoing curative intended primary radiotherapy alone.

METHODS

A systematic review of published and unpublished data identified 4805 patients with HNSCC treated in 32 randomized clinical trials, applying, normobaric oxygen or carbogen breathing (5 trials); hyperbaric oxygen (HBO) (9 trials); hypoxic radiosensitizers (17 trials) and HBO and radiosensitizer (1 trial). The trials were analysed with regard to the following endpoints: loco-regional control (32 trials), disease specific survival (30 trials), overall survival (29 trials), distant metastases (12 trials) and complications to radiotherapy (23 trials).

RESULTS

Overall hypoxic modification of radiotherapy in head and neck cancer did result in a significant improved therapeutic benefit. This was most dominantly observed when using the direct endpoint of loco-regional control with an odds ratio (OR) of 0.71, 95% cf.l. 0.63-0.80; p<0.001), but this was almost mirrored in the disease specific survival (OR: 0.73, 95% cf.l. 0.64-0.82; p<0.001), and to a lesser extent in the overall survival (OR: 0.87, 95% cf.l. 0.77-0.98; p=0.03). The risk of distant metastases was not significantly influenced although it appears to be less in the tumours treated with hypoxic modification (OR: 0.87, 95% cf.l. 0.69-1.09; p=0.22), whereas the radiation related late complications were not influenced by the overall use of hypoxic modifications (OR: 1.00, 95% cf.l. 0.82-1.23; p=0.96). The improvement in loco-regional control was found to be independent of the type of hypoxic modification. The trials have used different fractionation schedules, including large doses per fraction, which may result in relatively more hypoxia and greater benefit. However, analysis of HNSCC trials using conventional fractionation only, showed that the significant effect of hypoxic modification was maintained.

CONCLUSION

The meta-analysis thus demonstrates that there is level 1a evidence in favour of adding hypoxic modification to radiotherapy of squamous cell carcinomas of the head and neck.