Efficacy and toxicity of primary re-irradiation for malignant spinal cord compression based on radiobiological modelling: a phase II clinical trial.

BACKGROUND: The efficacy and safety of primary re-irradiation for MSCC are not known. Our aim was to establish the efficacy and safety of biologically effective dose-based re-irradiation. METHODS: Patients presenting with MSCC at a previously irradiated spine segment, and not proceeding with surgical decompression, were eligible. A 3 Gray per fraction experimental schedule (minimum 18 Gy/6 fractions, maximum 30 Gy/10 fractions) was used, delivering a maximum cumulative spinal dose of 100 Gy2 if the interval since the last radiotherapy was within 6 months, or 130 Gy2 if longer. The primary outcome was a change in mobility from week 1 to week 5 post-treatment, as assessed by the Tomita score. The RTOG SOMA score was used to screen for spinal toxicity, and an MRI performed to assess for radiation-induced myelopathy (RIM). RESULTS: Twenty-two patients were enroled, of whom eleven were evaluable for the primary outcome. Nine of eleven (81.8%) had stable or improved Tomita scores at 5 weeks. One of eight (12.5%) evaluable for late toxicity developed RIM. CONCLUSIONS: Re-irradiation is an efficacious treatment for MSCC. There is a risk of RIM with a cumulative dose of 120 Gy2. CLINICAL TRIAL REGISTRATION: Cancer Trials Ireland (ICORG 07-11); NCT00974168.

Prospective randomised phase II trial evaluating adjuvant pelvic radiotherapy using either IMRT or 3-Dimensional planning for endometrial cancer.

OBJECTIVE: To compare the incidence of grade ≥2 gastrointestinal (GI) or genitourinary (GU) toxicity for patients undergoing 3DRT versus IMRT in the postoperative setting for endometrial cancer. METHODS: Eligible patients were post-operatively randomly assigned to one of two parallel groups in a 1:1 ratio, to have their RT delivered using either a 3DRT technique or using IMRT. The prescription dose was 45 Gy in 25 fractions over 5 weeks followed by vaginal vault brachytherapy. Toxicity was graded according to National Cancer Institute (NCI) Common Terminology Criteria for Adverse Events (CTCAE) version (v) 3.0. Fisher's exact tests were used to test for associations between toxicity and arm. Differences in dosimetric parameters for patients with or without toxicity were tested using Mann-Whitney U-tests. RESULTS: 84 patients with a median age of 62 were evaluable for primary outcome. The median follow-up was 52 months. 14 (35%) participants from the 3DRT arm and 15 (34%) from the IMRT arm experienced acute grade ≥2 GI toxicity with older patients having a statistically higher risk of grade ≥2 acute GI toxicity. 20 (50%) participants from the 3DRT arm and 25 (57%) from the IMRT arm experienced acute grade ≥2 GI or GU toxicity (p = .662). 12 (30%) patients from the 3DRT arm and 17 (39%) from the IMRT arm experienced acute grade ≥2 GU toxicity (p = .493). CONCLUSION: Although IMRT can reduce dose to normal tissue, in this study no benefit in acute GI or GU toxicity outcome was seen.

A 4-Gene Signature of CDKN1, FDXR, SESN1 and PCNA Radiation Biomarkers for Prediction of Patient Radiosensitivity.

The quest for the discovery and validation of radiosensitivity biomarkers is ongoing and while conventional bioassays are well established as biomarkers, molecular advances have unveiled new emerging biomarkers. Herein, we present the validation of a new 4-gene signature panel of CDKN1, FDXR, SESN1 and PCNA previously reported to be radiation-responsive genes, using the conventional G2 chromosomal radiosensitivity assay. Radiation-induced G2 chromosomal radiosensitivity at 0.05 Gy and 0.5 Gy IR is presented for a healthy control (n = 45) and a prostate cancer (n = 14) donor cohort. For the prostate cancer cohort, data from two sampling time points (baseline and Androgen Deprivation Therapy (ADT)) is provided, and a significant difference (p > 0.001) between 0.05 Gy and 0.5 Gy was evident for all donor cohorts. Selected donor samples from each cohort also exposed to 0.05 Gy and 0.5 Gy IR were analysed for relative gene expression of the 4-gene signature. In the healthy donor cohort, there was a significant difference in gene expression between IR dose for CDKN1, FXDR and SESN1 but not PCNA and no significant difference found between all prostate cancer donors, unless they were classified as radiation-induced G2 chromosomal radiosensitive. Interestingly, ADT had an effect on radiation response for some donors highlighting intra-individual heterogeneity of prostate cancer donors.

Non-inferiority randomised phase 3 trial comparing two radiation schedules (single vs. five fractions) in malignant spinal cord compression.

BACKGROUND: The optimal EBRT schedule for MSCC is undetermined. Our aim was to determine whether a single fraction (SF) was non-inferior to five daily fractions (5Fx), for functional motor outcome. METHODS: Patients not proceeding with surgical decompression in this multicentre non-inferiority, Phase 3 trial were randomised to 10 Gy/SF or 20 Gy/5Fx. A change in mobility from baseline to 5 weeks for each patient, was evaluated by a Modified Tomita score: 1 = 'Walk unaided', 2 = 'With walking aid' and 3 = 'Bed-bound'. The margin used to establish non-inferiority was a detrimental change of -0.4 in the mean difference between arms. RESULTS: One-hundred and twelve eligible patients were enrolled. Seventy-three patients aged 30-87 were evaluated for the primary analysis. The 95% CI for the difference in the mean change in mobility scores between arms was -0.12 to 0.6. Since -0.4 is not included in the interval, there is evidence that 10 Gy/SF is non-inferior to 20 Gy/5Fx. One grade 3 AE was reported in the 5Fx arm. Twelve (26%) patients in the 5Fx arm had a Grade 2-3 AE compared with six (11%) patients in the SF arm (p = 0.093). CONCLUSION: For mobility preservation, one 10-Gy fraction is non-inferior to 20 Gy in five fractions, in patients with MSCC not proceeding with surgical decompression. CLINICAL TRIAL REGISTRATION: Cancer Trials Ireland ICORG 05-03; NCT00968643; EU-20952.

Discovery and Longitudinal Evaluation of Candidate Protein Biomarkers for Disease Recurrence in Prostate Cancer.

When compared with hormonal therapy alone, treatment with combined hormone and radiation therapy (CHRT) gives improved disease-specific survival outcomes for patients with prostate cancer; however, a significant number of CHRT patients still succumb to recurrent disease. The purpose of this study was to use longitudinal patient samples obtained as part of an ongoing noninterventional clinical trial (ICORG06-15) to identify and evaluate a potential serum protein signature of disease recurrence. Label-free LC-MS/MS based protein discovery was undertaken on depleted serum samples from CHRT patients who showed evidence of disease recurrence (n = 3) and time-matched patient controls (n = 3). A total of 104 proteins showed a significant change between these two groups. Multiple reaction monitoring (MRM) assays were designed for a subset of these proteins as part of a panel of putative prostate cancer biomarkers (41 proteins) for evaluation in longitudinal serum samples. These data revealed significant interpatient variability in individual protein expression between time of diagnosis, disease recurrence, and beyond and serve to highlight the importance of longitudinal patient samples for evaluating the use of candidate protein biomarkers in disease monitoring.

The SARS-CoV-2 Pandemic and Cancer Trials Ireland: Impact, Resolution and Legacy.

BACKGROUND: Cancer Trials Ireland (CTI) is the national cooperative group in Ireland. The SARS-CoV-2 pandemic led to significant ongoing disruptive change in healthcare from March 2020 to the present day. Its impact and legacy on a national clinical trials organisation was assessed. METHODS: A review was conducted of prospectively acquired communications, team logs and time sheets, trial activation, closure and accrual, for the period 2019 to September 2021. An online survey of the impact of the pandemic on clinical investigators and of clinical trials units was performed. A National Cancer Retreat was organised on 21 May 2021 to identify and address pandemic related disruption and develop adaptive strategies. RESULTS: In the weeks after the pandemic was declared, remote working was initiated by all central office staff. Nationally, clinical trial accrual fell by 54% compared to the same period in 2019, radiotherapy trial accrual by 90%, and translational studies by 36%. Staff reassignment of research nurse staff occurred in 60% of units, trial monitoring was reduced in 42%, and trial initiations fell by 67%. Extreme fluctuations in monitoring hours were noted paralleling lockdown measures. Significant impact on all clinical trials units was noted including staff reassignments, reduced access to diagnostic imaging and reduced institutional supports. Remote clinic visits and remote monitoring was widely adopted. The National Cancer Retreat identified flexibility in trial conduct, staff recruitment and retention, the need for harmonisation of processes, and research staff support in the context of remote working as priorities. CONCLUSION: The pandemic has had a significant ongoing negative impact on cancer clinical trial activity in Ireland. Adaptive strategies including trial flexibility, expanded telehealth and remote monitoring, harmonisation of processes and staff support have been identified as priorities to ameliorate this impact, and develop a more sustainable clinical trial ecosystem.

Perinatal social work during the Covid-19 pandemic: Reflecting on concepts of time and liminality.

This article reflects upon the experiences of two perinatal, hospital social workers during the unprecedented time of the Covid-19 in Ireland, as discussed with their academic colleague. This encounter revealed the complexity of service delivery that emerged, when managing the needs of vulnerable clients whilst being mindful of personal safety. One of the social workers was pregnant so was conscious of possible risks to her unborn child, as well as her young family at home. The second social worker, her line manager, discusses the dilemmas associated with the management of risk when allocating staff to contexts where they would be in direct contact with Covid-19. At the core of the analysis of these situations is the notion of liminal space and the realisation that time appears to have a new meaning; what we once knew as normal no longer exists, but we have yet to reach the 'new normal'.

Vibrational spectroscopy of liquid biopsies for prostate cancer diagnosis.

BACKGROUND: Screening for prostate cancer with prostate specific antigen and digital rectal examination allows early diagnosis of prostate malignancy but has been associated with poor sensitivity and specificity. There is also a considerable risk of over-diagnosis and over-treatment, which highlights the need for better tools for diagnosis of prostate cancer. This study investigates the potential of high throughput Raman and Fourier Transform Infrared (FTIR) spectroscopy of liquid biopsies for rapid and accurate diagnosis of prostate cancer. METHODS: Blood samples (plasma and lymphocytes) were obtained from healthy control subjects and prostate cancer patients. FTIR and Raman spectra were recorded from plasma samples, while Raman spectra were recorded from the lymphocytes. The acquired spectral data was analysed with various multivariate statistical methods, principal component analysis (PCA), partial least squares discriminant analysis (PLS-DA) and classical least squares (CLS) fitting analysis. RESULTS: Discrimination was observed between the infrared and Raman spectra of plasma and lymphocytes from healthy donors and prostate cancer patients using PCA. In addition, plasma and lymphocytes displayed differentiating signatures in patients exhibiting different Gleason scores. A PLS-DA model was able to discriminate these groups with sensitivity and specificity rates ranging from 90% to 99%. CLS fitting analysis identified key analytes that are involved in the development and progression of prostate cancer. CONCLUSIONS: This technology may have potential as an alternative first stage diagnostic triage for prostate cancer. This technology can be easily adaptable to many other bodily fluids and could be useful for translation of liquid biopsy-based diagnostics into the clinic.

Effect of hemolysis on Fourier transform infrared and Raman spectra of blood plasma.

Hemolysis is a very common phenomenon and is referred as the release of intracellular components from red blood cells to the extracellular fluid. Hemolyzed samples are often rejected in clinics due to the interference of hemoglobin and intracellular components in laboratory measurements. Plasma and serum based vibrational spectroscopy studies are extensively applied to generate spectral biomarkers for various diseases. However, no studies have reported the effect of hemolysis in blood based vibrational spectroscopy studies. This study was undertaken to evaluate the effect of hemolysis on infrared and Raman spectra of blood plasma. In this study, prostate cancer plasma samples (n = 30) were divided into three groups (nonhemolyzed, mildly hemolyzed, and moderately hemolyzed) based on the degree of hemolysis and FTIR and Raman spectra were recorded using high throughput (HT)-FTIR and HT-Raman spectroscopy. Discrimination was observed between the infrared and Raman spectra of nonhemolyzed and hemolyzed plasma samples using principal component analysis. A classical least square fitting analysis showed differences in the weighting of pure components in nonhemolyzed and hemolyzed plasma samples. Therefore, it is worth to consider the changes in spectral features due to hemolysis when comparing the results within and between experiments.

Prediction of DNA damage and G2 chromosomal radio-sensitivity ex vivo in peripheral blood mononuclear cells with label-free Raman micro-spectroscopy.

PURPOSE: Liquid biopsies are a potentially rich store of biochemical information that can be linked to an individual's response to therapeutic treatments, including radiotherapy, and which may ultimately play a role in the individualization of treatment regimens. Peripheral blood mononuclear cells (PBMCs) can be used not only for the biochemical profiling of the individual, but also, being living cells, can provide insights into the individuals response to ionizing radiation exposure. MATERIALS AND METHODS: The present study attempts to link the biochemical profile of lymphocytes within PBMCs obtained through Raman spectroscopy to in vitro measures of low-dose (<0.5Gy) DNA damage response and cytogenetic metrics of radiosensitivity in a cohort of healthy controls and prostate cancer patients (from CTRIAL-IE(ICORG) 08-17, NCT00951535). All parallel metrics to the Raman spectra of the cells were obtained ex vivo in cycling peripheral blood lymphocytes, with radiosensitivity estimated using the G2 chromosomal assay and DNA damage assessed using γH2AX fluorescence. Spectra from a total of 26 healthy volunteers and 22 prostate cancer patients were obtained. RESULTS: The links between both measures of cellular response to ionizing radiation and the Raman spectra were modeled using partial least squares regression (PLSR) and support-vector regression (SVR). It was found that neither regression approach could predict radiation-induced G2 score well, but could predict γH2AX MFI with the SVR outperforming PLSR, implying a non-linear relationship between spectral measurements and measures of DNA damage. CONCLUSIONS: Raman spectroscopy of PBMCs represents a label-free approach for prediction of DNA damage levels for either prospective or retrospective analysis.

Monitoring Radiotherapeutic Response in Prostate Cancer Patients Using High Throughput FTIR Spectroscopy of Liquid Biopsies.

Radiation therapy (RT) is used to treat approximately 50% of all cancer patients. However, RT causes a wide range of adverse late effects that can affect a patient's quality of life. There are currently no predictive assays in clinical use to identify patients at risk of normal tissue radiation toxicity. This study aimed to investigate the potential of Fourier transform infrared (FTIR) spectroscopy for monitoring radiotherapeutic response. Blood plasma was acquired from 53 prostate cancer patients at five different time points: prior to treatment, after hormone treatment, at the end of radiotherapy, two months post radiotherapy and eight months post radiotherapy. FTIR spectra were recorded from plasma samples at all time points and the data was analysed using MATLAB software. Discrimination was observed between spectra recorded at baseline versus follow up time points, as well as between spectra from patients showing minimal and severe acute and late toxicity using principal component analysis. A partial least squares discriminant analysis model achieved sensitivity and specificity rates ranging from 80% to 99%. This technology may have potential to monitor radiotherapeutic response in prostate cancer patients using non-invasive blood plasma samples and could lead to individualised patient radiotherapy.

Antiangiogenics and radiotherapy.

Antiangiogenic therapies are one of the fore-runners of the new generation of anticancer drugs aimed at tumour-specific molecular targets. Up until the beginning of this century, the general opinion was that targeted agents should show antitumour activity when used as single agents. However, it has now become clear that much greater improvements in therapeutic activity may be achieved by combining the novel agents with conventional cytotoxic therapies already in use in the clinic. Radiotherapy is currently used to treat half of all cancer patients at some stage in their therapy, although the development of radioresistance is an ongoing problem. It is therefore reasonable to expect that any novel molecularly-targeted agent which reaches the clinic will be used in combination with radiotherapy. The rationale for combining antiangiogenics in particular with radiotherapy exists, as radiotherapy has been shown to kill proliferating endothelial cells, suggesting that inhibiting angiogenesis may sensitise endothelial cells to the effects of radiation. Furthermore, targeting the vasculature may paradoxically increase oxygenation within tumours, thereby enhancing radiotherapy efficacy. In this review we present an update on the use of antiangiogenic methods in combination with radiotherapy.

Combining radiotherapy with AZD2171, a potent inhibitor of vascular endothelial growth factor signaling: pathophysiologic effects and therapeutic benefit.

AZD2171 is a highly potent, orally active inhibitor of vascular endothelial growth factor receptor signaling. The potential for AZD2171 to enhance the antitumor effects of radiotherapy was investigated in lung (Calu-6) and colon (LoVo) human tumor xenograft models. Combined treatment resulted in a significantly enhanced growth delay compared with either modality alone. The enhancement was independent of whether chronic once daily AZD2171 treatment was given 2 h prior to each radiation fraction (2 Gy daily for 3 or 5 consecutive days), and daily thereafter, or commenced immediately following the course of radiotherapy. Histologic assessments revealed that 5 days of radiation (2 Gy) or AZD2171 (3 or 6 mg/kg/d) reduced vessel density and perfusion. Concomitant AZD2171 and radiation enhanced this effect and produced a significant increase in tumor hypoxia. Concomitant AZD2171 (6 mg/kg/d) was also found to reduce tumor growth significantly during the course of radiotherapy (5 x 2 Gy). However, the extent and duration of tumor regression observed postradiotherapy was similar to sequentially treated tumors, suggesting that preirradiated tumors were sensitized to AZD2171 treatment. An enhanced antivascular effect of administering AZD2171 postradiotherapy was observed in real-time in Calu-6 tumors grown in dorsal window chambers. Collectively, these data support the clinical development of AZD2171 in combination with radiotherapy.

Cancer Trials Ireland (ICORG) 06-34: A multi-centre clinical trial using three-dimensional conformal radiation therapy to reduce the toxicity of palliative radiation for lung cancer.

TITLE: Cancer Trials Ireland (ICORG) 06-34: A multi-centre clinical trial using three-dimensional conformal radiation therapy to reduce the toxicity of palliative radiation for lung cancer. NCT01176487. BACKGROUND & PURPOSE: Trials of radiation therapy for the palliation of intra-thoracic symptoms from locally advanced non-small cell lung cancer (NSCLC) have concentrated on optimising fractionation and dose schedules. In these trials, the rates of oesophagitis induced by this "palliative" therapy have been unacceptably high. In contrast, this non-randomised, single-arm trial was designed to assess if more technically advanced treatment techniques would result in equivalent symptom relief and reduce the side-effect of symptomatic oesophagitis. MATERIALS & METHODS: Thirty-five evaluable patients with symptomatic locally advanced or metastatic NSCLC were treated using a three-dimensional conformal technique (3-DCRT) and standardised dose regimens of 39 Gy in 13 fractions, 20 Gy in 5 fractions or 17 Gy in 2 fractions. Treatment plans sought to minimise oesophageal dose. Oesophagitis was recorded during treatment, at two weeks, one month and three months following radiation therapy and 3-6 monthly thereafter. Mean dose to the irradiated oesophagus was calculated for all treatment plans. RESULTS: Five patients (14%) had experienced grade 2 oesophagitis or dysphagia or both during treatment and 2 other patients had these side effects at the 2-week follow-up. At follow-up of one month after therapy, there was no grade two or higher oesophagitis or dysphagia reported. 22 patients were eligible for assessment of late toxicity. Five of these patients reported oesophagitis or dysphagia (one had grade 3 dysphagia, two had grade 2 oesophagitis, one of whom also had grade 2 dysphagia). Quality of Life (QoL) data at baseline and at 1-month follow up were available for 20 patients. At 1-month post radiation therapy, these patients had slightly less trouble taking a short walk, less shortness of breath, did not feel as weak, had better appetite and generally had a better overall quality of life than they did at baseline. They did report being slightly more tired. CONCLUSIONS: This trial is the first of its kind showing that 3-DCRT provides patients with lower rates of oesophageal toxicity whilst yielding acceptable rates of symptom control. (Sponsored by Cancer Trials Ireland (ICORG) Study number 06-34, the Friends of St. Luke's and the St. Luke's Institute of Cancer Research.).

Oncological implications of hypoxia inducible factor-1alpha (HIF-1alpha) expression.

Solid tumours contain regions of hypoxia, which may be a prognostic indicator and determinant of malignant progression, metastatic development and chemoradio-resistance. The degree of intra-tumoural hypoxia has been shown to be positively correlated with the expression of the transcription factor hypoxia-inducible factor 1. HIF-1 is composed of 2 sub-units, namely HIF-1alpha and HIF-1beta. The production of hypoxia inducible factor 1-alpha has been identified as a key element in allowing cells to adapt and survive in a hostile hypoxic environment via a variety of pathways. HIF-1alpha is stabilised by hypoxia at the protein level, and also by the oncogenes HER2neu, v-src and ras. There are over 60 target genes for HIF-1, many of which are activated in cancers in comparison to equivalent normal tissues. Chemotherapeutic modulation of HIF-1 pathways has shown promise for patients with chemo-radio resistant or recurrent tumours in Phase II clinical trials. We herein review the existing literature on hypoxia inducible factor-1alpha, particularly its role in carcinogenesis and clinical implications of its over-expression.

Tumour hypoxia, chemotherapeutic resistance and hypoxia-related therapies.

Tissue hypoxia occurs where there is an imbalance between oxygen supply and consumption. Hypoxia occurs in solid tumours as a result of an inadequate supply of oxygen, due to exponential cellular proliferation and an inefficient vascular supply. It is an adverse prognostic indicator in cancer as it is associated with tumour progression and resistance to therapy. The expression of several genes controlling tumour cell survival are regulated by hypoxia, e.g., growth factors governing the formation of new blood vessels, and hypoxia-responsive transcription factors modulating the expression of genes, which promote tumour cell survival. This review outlines some of the pathways by which tumour hypoxia leads to chemotherapeutic resistance, directly due to lack of oxygen availability, and indirectly due to alterations in the proteome/genome, angiogenesis and pH changes. Some innovative therapies are also detailed which may potentially minimise or eliminate these problems associated with targeting solid tumours.

Examining changes in [18 F]FDG and [18 F]FLT uptake in U87-MG glioma xenografts as early response biomarkers to treatment with the dual mTOR1/2 inhibitor AZD8055.

PURPOSE: The mTOR kinase inhibitor AZD8055 inhibits both mTORC1 and mTORC2 leading to disruption of glucose metabolism and proliferation pathways. This study assessed the impact of single and multiple doses of AZD8055 on the uptake of the glucose metabolism marker 2-deoxy-2-[(18) F]fluoro-D-glucose ([(18) F]FDG) and the proliferation marker 3'-deoxy-3'-[(18) F]fluorothymidine ([(18) F]FLT) in U87-MG glioma xenografts. PROCEDURES: Mice bearing U87-MG tumours received either vehicle or AZD8055 (20 mg/kg) once daily p.o. Mice were imaged with either [(18) F]FDG or [(18) F]FLT PET to assess treatment response. Comparisons were made between in vivo imaging and ex vivo histopathology data. RESULTS: Tumour uptake of [(18) F]FDG was reduced by 33 % 1 h after a single dose of AZD8055 and by 49 % following 4 days of dosing. These changes coincided with suppression of the mTOR pathway biomarkers pS6 and pAKT. In contrast, the effect of AZD8055 on [(18) F]FLT uptake was inconsistent. CONCLUSIONS: The very rapid change in [(18) F]FDG uptake following acute AZD8055 treatment suggests that this could be used as an early mechanistic biomarker of metabolic changes resulting from mTOR inhibition. The utility of [(18) F]FLT for measuring the anti-proliferative effect of AZD8055 remains unclear.

Development of a label-free LC-MS/MS strategy to approach the identification of candidate protein biomarkers of disease recurrence in prostate cancer patients in a clinical trial of combined hormone and radiation therapy.

PURPOSE: Combined hormone and radiation therapy (CHRT) is one of the principle curative regimes for localised prostate cancer (PCa). Following treatment, many patients subsequently experience disease recurrence however; current diagnostics tests fail to predict the onset of disease recurrence. Biomarkers that address this issue would be of significant advantage. EXPERIMENTAL DESIGN: Label-free LC-MS/MS for protein biomarker discovery and MRM for targeted confirmation were applied to patient serum samples accrued in a non-interventional clinical trial of CHRT. RESULTS: Analysis of time-matched patient samples from a patient with disease recurrence compared with a time match disease-free individual supported the identification of 287 proteins. Of these, 141 proteins were quantified, 95 proteins changed in their expression (P ≤ 0.05 and ≥1.5-fold change) and of these 16 were selected for MRM confirmation. The protein expression changes observed in the label-free LC-MS/MS and MRM analysis were found to be highly correlated (R(2) = 0.85). CONCLUSIONS AND CLINICAL RELEVANCE: The establishment of a clinical trial to support the acquisition of samples and development of a pipeline for MS-based biomarker discovery and validation should contribute to the identification of a serum protein signature to predict or monitor the outcome of treatment of patients with PCa.

An evaluation of 2-deoxy-2-[18F]fluoro-D-glucose and 3'-deoxy-3'-[18F]-fluorothymidine uptake in human tumor xenograft models.

PURPOSE: The aim of this study is to assess the variability of 2-deoxy-2-[(18)F]fluoro-D: -glucose ([(18)F]-FDG) and 3'-deoxy-3'-[(18)F]-fluorothymidine ([(18)F]-FLT) uptake in pre-clinical tumor models and examine the relationship between imaging data and related histological biomarkers. PROCEDURES: [(18)F]-FDG and [(18)F]-FLT studies were carried out in nine human tumor xenograft models in mice. A selection of the models underwent histological analysis for endpoints relevant to radiotracer uptake. Comparisons were made between in vitro uptake, in vivo imaging, and ex vivo histopathology data using quantitative and semi-quantitative analysis. RESULTS: In vitro data revealed that [1-(14)C]-2-deoxy-D: -glucose ([(14)C]-2DG) uptake in the tumor cell lines was variable. In vivo, [(18)F]-FDG and [(18)F]-FLT uptake was highly variable across tumor types and uptake of one tracer was not predictive for the other. [(14)C]-2DG uptake in vitro did not predict for [(18)F]-FDG uptake in vivo. [(18)F]-FDG SUV was inversely proportional to Ki67 and necrosis levels and positively correlated with HKI. [(18)F]-FLT uptake positively correlated with Ki67 and TK1. CONCLUSION: When evaluating imaging biomarkers in response to therapy, the choice of tumor model should take into account in vivo baseline radiotracer uptake, which can vary significantly between models.

The mitogen-activated protein/extracellular signal-regulated kinase kinase 1/2 inhibitor AZD6244 (ARRY-142886) enhances the radiation responsiveness of lung and colorectal tumor xenografts.

PURPOSE: Novel molecularly targeted agents, given in combination with radiotherapy, have the potential to increase tumor response rates and the survival of patients with lung cancer. AZD6244 is a potent and selective inhibitor of mitogen-activated protein kinase (MAPK) kinase 1/2 (MEK1/2), a critical enzyme within the MAPK/extracellular signal-regulated kinase (ERK) signaling pathway that regulates the proliferation and survival of tumor cells. EXPERIMENTAL DESIGN: This study examined the potential benefit of combining AZD6244 with fractionated radiotherapy using human lung and colon carcinoma xenograft models. RESULTS: AZD6244 reduced ERK phosphorylation in Calu-6 lung cancer cells in vitro. Administration of AZD6244 for 10 days (25 mg/kg twice daily p.o.) inhibited the tumor growth of Calu-6 xenografts, with regrowth occurring on cessation of drug treatment. When fractionated tumor-localized radiotherapy (5 x 2 Gy) was combined with AZD6244 treatment, the tumor growth delay was enhanced significantly when compared with either modality alone, and this effect was also seen in a colon tumor model. We examined the effect of inhibiting MEK1/2 on the molecular responses to hypoxia, a potential interaction that could contribute to radioresponsiveness. AZD6244 reduced hypoxia-inducible factor-specific transactivation in vivo, shown using Calu-6 dual clone cells that stably express a Firefly luciferase gene under the control of a hypoxia-driven promoter. Furthermore, hypoxia-inducible factor-1 alpha, GLUT-1, and vascular endothelial growth factor levels were reduced by AZD6244, and there was a significant decrease in vascular perfusion in the tumors given combination treatment when compared with the other treatment groups. CONCLUSIONS: These data provide support for the clinical development of AZD6244 in combination with radiotherapy and indicate a potential role for AZD6244 in inhibiting the tumor hypoxia response.