Therese Seierstad

Vorinostat, a histone deacetylase inhibitor, combined with pelvic palliative radiotherapy for gastrointestinal carcinoma: the Pelvic Radiation and Vorinostat (PRAVO) phase 1 study.

BACKGROUND Histone deacetylase (HDAC) inhibitors have shown radiosensitising activity in preclinical tumour models. This phase 1 study assessed the use of vorinostat combined with pelvic palliative radiotherapy for gastrointestinal carcinoma. METHODS Between Feb 14, 2007, and May 18, 2009, eligible patients with histologically confirmed carcinoma, scheduled to receive pelvic palliative radiation to 30 Gy in 3 Gy daily fractions over 2 weeks, were enrolled into cohorts of escalating vorinostat dose. Vorinostat was administered orally once daily, 3 h before each radiotherapy fraction, at the following dose levels: 100 mg (n=1), 200 mg (n=4), 300 mg (n=6), and 400 mg (n=6). Endpoints included safety, tolerability, and biological activity (tumour histone acetylation). This study is registered with ClinicalTrials.gov, number NCT00455351. FINDINGS One patient withdrew consent after one treatment day, leaving 16 patients evaluable for tolerability. Most recorded adverse events were grade 1 and 2, among which fatigue (all patients) and gastrointestinal events (all patients) were most common. Grade 3 adverse events included fatigue (n=5), anorexia (n=3), diarrhoea (n=2), hyponatraemia (n=1), hypokalaemia (n=1), and acneiform rash (n=1). Of these, treatment-related grade 3 events (ie, dose-limiting toxicities) were observed in one of six patients at vorinostat 300 mg once daily (fatigue and anorexia), and in two of six patients at vorinostat 400 mg once daily (two events of diarrhoea and one each of fatigue, anorexia, hyponatraemia, and hypokalaemia). The maximum-tolerated dose of vorinostat in combination with palliative radiotherapy was thus determined to be 300 mg once daily. Histone hyperacetylation was detected, indicating biological activity of vorinostat. INTERPRETATION Vorinostat can be safely combined with short-term pelvic palliative radiotherapy. This study highlights the potential use of HDAC inhibitors with radiation, and suggests investigation of vorinostat in long-term curative pelvic radiotherapy--eg, as a component of preoperative chemoradiotherapy for rectal cancer. FUNDING Merck & Co, Inc, Norwegian Cancer Society, Norwegian Health and Rehabilitation Foundation.

Diffusion-weighted magnetic resonance imaging for pretreatment prediction and monitoring of treatment response of patients with locally advanced breast cancer undergoing neoadjuvant chemotherapy

Abstract Background. For patients with locally advanced breast cancer (LABC) undergoing neoadjuvant chemotherapy (NACT), the European Guidelines for Breast Imaging recommends magnetic resonance imaging (MRI) to be performed before start of NACT, when half of the NACT has been administered and prior to surgery. This is the first study addressing the value of flow-insensitive apparent diffusion coefficients (ADCs) obtained from diffusion-weighted (DW) MRI at the recommended time points for pretreatment prediction and monitoring of treatment response. Materials and methods. Twenty-five LABC patients were included in this prospective study. DW MRI was performed using single-shot spin-echo echo-planar imaging with b-values of 100, 250 and 800 s/mm2 prior to NACT, after four cycles of NACT and at the conclusion of therapy using a 1.5 T MR scanner. ADC in the breast tumor was calculated from each assessment. The strength of correlation between pretreatment ADC, ADC changes and tumor volume changes were examined using Spearman’s rho correlation test. Results. Mean pretreatment ADC was 1.11 ± 0.21 × 10–3 mm2/s. After 4 cycles of NACT, ADC was significantly increased (1.39 ± 0.36 × 10–3 mm2/s; p=0.018). There was no correlation between individual pretreatment breast tumor ADC and MR response measured after four cycles of NACT (p=0.816) or prior to surgery (p=0.620). Conclusion. Pretreatment tumor ADC does not predict treatment response for patients with LABC undergoing NACT. Furthermore, ADC increase observed mid-way in the course of NACT does not correlate with tumor volume changes.

Identification of prostate cancer biomarkers in urinary exosomes

Exosomes have recently appeared as a novel source of non-invasive cancer biomarkers since tumour-specific molecules can be found in exosomes isolated from biological fluids. We have here investigated the proteome of urinary exosomes by using mass spectrometry to identify proteins differentially expressed in prostate cancer patients compared to healthy male controls. In total, 15 control and 16 prostate cancer samples of urinary exosomes were analyzed. Importantly, 246 proteins were differentially expressed in the two groups. The majority of these proteins (221) were up-regulated in exosomes from prostate cancer patients. These proteins were analyzed according to specific criteria to create a focus list that contained 37 proteins. At 100% specificity, 17 of these proteins displayed individual sensitivities above 60%. Even though several of these proteins showed high sensitivity and specificity for prostate cancer as individual biomarkers, combining them in a multi-panel test has the potential for full differentiation of prostate cancer from non-disease controls. The highest sensitivity, 94%, was observed for transmembrane protein 256 (TM256; chromosome 17 open reading frame 61). LAMTOR proteins were also distinctly enriched with very high specificity for patient samples. TM256 and LAMTOR1 could be used to augment the sensitivity to 100%. Other prominent proteins were V-type proton ATPase 16 kDa proteolipid subunit (VATL), adipogenesis regulatory factor (ADIRF), and several Rab-class members and proteasomal proteins. In conclusion, this study clearly shows the potential of using urinary exosomes in the diagnosis and clinical management of prostate cancer.

Principal component analysis for the comparison of metabolic profiles from human rectal cancer biopsies and colorectal xenografts using high-resolution magic angle spinning 1H magnetic resonance spectroscopy

BackgroundThis study was conducted in order to elucidate metabolic differences between human rectal cancer biopsies and colorectal HT29, HCT116 and SW620 xenografts by using high-resolution magnetic angle spinning (MAS) magnetic resonance spectroscopy (MRS) and for determination of the most appropriate human rectal xenograft model for preclinical MR spectroscopy studies. A further aim was to investigate metabolic changes following irradiation of HT29 xenografts.MethodsHR MAS MRS of tissue samples from xenografts and rectal biopsies were obtained with a Bruker Avance DRX600 spectrometer and analyzed using principal component analysis (PCA) and partial least square (PLS) regression analysis.Results and conclusionHR MAS MRS enabled assignment of 27 metabolites. Score plots from PCA of spin-echo and single-pulse spectra revealed separate clusters of the different xenografts and rectal biopsies, reflecting underlying differences in metabolite composition. The loading profile indicated that clustering was mainly based on differences in relative amounts of lipids, lactate and choline-containing compounds, with HT29 exhibiting the metabolic profile most similar to human rectal cancers tissue. Due to high necrotic fractions in the HT29 xenografts, radiation-induced changes were not detected when comparing spectra from untreated and irradiated HT29 xenografts. However, PLS calibration relating spectral data to the necrotic fraction revealed a significant correlation, indicating that necrotic fraction can be assessed from the MR spectra.

The tumour hypoxia marker pimonidazole reflects a transcriptional programme associated with aggressive prostate cancer

Background:The hypoxia marker pimonidazole is a candidate biomarker of cancer aggressiveness. We investigated the transcriptional programme associated with pimonidazole staining in prostate cancer.Methods:Index tumour biopsies were taken by image guidance from an investigation cohort of 52 patients, where 43 patients received pimonidazole before prostatectomy. Biopsy location within the index tumour was verified for 46 (88%) patients, who were included for gene expression profiling and immunohistochemistry. Two independent cohorts of 59 and 281 patients were used for validation.Results:Expression of genes in proliferation, DNA repair and hypoxia response was a major part of the transcriptional programme associated with pimonidazole staining. A signature of 32 essential genes was constructed and showed positive correlation to Ki67 staining, confirming the increased proliferation in hypoxic tumours as suggested from the gene data. Positive correlations were also found to tumour stage and lymph node status, but not to blood prostate-specific antigen level, consistent with the findings for pimonidazole staining. The association with aggressiveness was confirmed in validation cohorts, where the signature correlated with Gleason score and had independent prognostic impact, respectively.Conclusions:Pimonidazole staining reflects an aggressive hypoxic phenotype of prostate cancer characterised by upregulation of proliferation, DNA repair and hypoxia response genes.

Preclinical dynamic 18F-FDG PET – tumor characterization and radiotherapy response assessment by kinetic compartment analysis

Abstract Background. Non-invasive visualization of tumor biological and molecular processes of importance to diagnosis and treatment response is likely to be critical in individualized cancer therapy. Since conventional static 18F-FDG PET with calculation of the semi-quantitative parameter standardized uptake value (SUV) may be subject to many sources of variability, we here present an approach of quantifying the 18F-FDG uptake by analytic two-tissue compartment modeling, extracting kinetic tumor parameters from dynamic 18F-FDG PET. Further, we evaluate the potential of such parameters in radiotherapy response assessment. Material and methods. Male, athymic mice with prostate carcinoma xenografts were subjected to dynamic PET either untreated (n=8) or 24 h post-irradiation (7.5 Gy single dose, n=8). After 10 h of fasting, intravenous bolus injections of 10–15 MBq 18F-FDG were administered and a 1 h dynamic PET scan was performed. 4D emission data were reconstructed using OSEM-MAP, before remote post-processing. Individual arterial input functions were extracted from the image series. Subsequently, tumor 18F-FDG uptake was fitted voxel-by-voxel to a compartment model, producing kinetic parameter maps. Results. The kinetic model separated the 18F-FDG uptake into free and bound tracer and quantified three parameters; forward tracer diffusion (k1), backward tracer diffusion (k2), and rate of 18F-FDG phosphorylation, i.e. the glucose metabolism (k3). The fitted kinetic model gave a goodness of fit (r2) to the observed data ranging from 0.91 to 0.99, and produced parametrical images of all tumors included in the study. Untreated tumors showed homogeneous intra-group median values of all three parameters (k1, k2 and k3), whereas the parameters significantly increased in the tumors irradiated 24 h prior to 18F-FDG PET. Conclusions. This study demonstrates the feasibility of a two-tissue compartment kinetic analysis of dynamic 18F-FDG PET images. If validated, extracted parametrical maps might contribute to tumor biological characterization and radiotherapy response assessment.

Early prediction of response to radiotherapy and androgen-deprivation therapy in prostate cancer by repeated functional MRI: a preclinical study

BackgroundIn modern cancer medicine, morphological magnetic resonance imaging (MRI) is routinely used in diagnostics, treatment planning and assessment of therapeutic efficacy. During the past decade, functional imaging techniques like diffusion-weighted (DW) MRI and dynamic contrast-enhanced (DCE) MRI have increasingly been included into imaging protocols, allowing extraction of intratumoral information of underlying vascular, molecular and physiological mechanisms, not available in morphological images. Separately, pre-treatment and early changes in functional parameters obtained from DWMRI and DCEMRI have shown potential in predicting therapy response. We hypothesized that the combination of several functional parameters increased the predictive power.MethodsWe challenged this hypothesis by using an artificial neural network (ANN) approach, exploiting nonlinear relationships between individual variables, which is particularly suitable in treatment response prediction involving complex cancer data. A clinical scenario was elicited by using 32 mice with human prostate carcinoma xenografts receiving combinations of androgen-deprivation therapy and/or radiotherapy. Pre-radiation and on days 1 and 9 following radiation three repeated DWMRI and DCEMRI acquisitions enabled derivation of the apparent diffusion coefficient (ADC) and the vascular biomarker Ktrans, which together with tumor volumes and the established biomarker prostate-specific antigen (PSA), were used as inputs to a back propagation neural network, independently and combined, in order to explore their feasibility of predicting individual treatment response measured as 30 days post-RT tumor volumes.ResultsADC, volumes and PSA as inputs to the model revealed a correlation coefficient of 0.54 (p < 0.001) between predicted and measured treatment response, while Ktrans, volumes and PSA gave a correlation coefficient of 0.66 (p < 0.001). The combination of all parameters (ADC, Ktrans, volumes, PSA) successfully predicted treatment response with a correlation coefficient of 0.85 (p < 0.001).ConclusionsWe have in a preclinical investigation showed that the combination of early changes in several functional MRI parameters provides additional information about therapy response. If such an approach could be clinically validated, it may become a tool to help identifying non-responding patients early in treatment, allowing these patients to be considered for alternative treatment strategies, and, thus, providing a contribution to the development of individualized cancer therapy.

MR-guided simultaneous integrated boost in preoperative radiotherapy of locally advanced rectal cancer following neoadjuvant chemotherapy

PURPOSE To evaluate a simultaneous integrated boost (SIB) strategy in preoperative radiotherapy of rectal cancer patients following neoadjuvant chemotherapy using pre- and post-chemotherapy tumor volumes assessed by MRI. MATERIALS AND METHODS Ten patients with locally advanced rectal cancer, receiving chemotherapy prior to radiotherapy, were included in this study. Pre- and post-chemotherapy MR tumor images were co-registered with CT images for IMRT planning. Three planning target volumes were defined: PTV(risk), PTV(pre_chemo) and PTV(post_chemo). For SIB, prescribed mean doses to the PTVs were 46, 50 and 58 Gy, respectively, given in 25 fractions. Organs at risk (OARs) were bladder and intestine. The novel three-volume SIB strategy was compared to a conventional two-volume SIB plan, in which PTV(post_chemo) was ignored, using dose-volume histograms (DVHs) and the generalized equivalent uniform dose (gEUD). RESULTS All patients showed tumor shrinkage following chemotherapy. For the novel SIB, population-based mean doses given to PTV(risk), PTV(pre_chemo) and PTV(post_chemo) were 46.8+/-0.3, 50.6+/-0.4 and 58.1+/-0.4 Gy, respectively. DVHs and gEUDs for PTV(risk), PTV(pre_chemo), bladder and intestine revealed minimal differences between the two SIB strategies. CONCLUSIONS Tumor volume reduction for rectal cancer patients following neoadjuvant chemotherapy allows for increased tumor dose using a SIB strategy without increased OAR toxicity.

Diffusion-weighted MRI compared to FDG PET/CT for assessment of early treatment response in lymphoma.

Background 18F fluoro-deoxyglucose (FDG) positron emission tomography / computed tomography (PET/CT) is a well-recognized diagnostic tool used for staging and monitoring of therapy response for lymphomas. During the past decade diffusion-weighted (DW) magnetic resonance imaging (MRI) is increasingly being included in the assessment of tumor response for various cancers. Purpose To compare the change in maximum standardized uptake value (ΔSUVmax) from FDG PET/CT with the change in apparent diffusion coefficient (ΔADC) from DW MRI after initiation of the first cycle of chemotherapy in patients with Hodgkins lymphoma (HL) and in patients with diffuse large B-cell lymphoma (DLBCL). Material and Methods Twenty-seven consecutive patients with histologically proven lymphoma and lymphomatous lymph nodes (LLN) of the neck (19 with HL, 8 with DLBCL) underwent FDG PET/CT and MRI of the neck before and after initiation of the first cycle of chemotherapy. The mean time interval from initiation of chemotherapy to imaging was 19 days and 2 days for FDG PET/CT and MRI, respectively. For each patient ΔSUVmax, ΔADC, and change in volume of the same LLN were compared. Results There was a significant mean decrease of SUVmax by 70%, but no significant change in ADC. There was no significant reduction in LLN volume. Conclusion There was no significant correlation between ΔSUVmax and ΔADC. Thus, our data do not support that FDG PET/CT can be replaced by early DW MRI for response evaluation in lymphoma patients.

Dynamic 18F-FDG-PET for monitoring treatment effect following anti-angiogenic therapy in triple-negative breast cancer xenografts

Abstract Introduction. Dynamic 18F-FDG PET allows the study of glucose distribution in tissues as a function of time and space. Using pharmacokinetics, the temporal uptake pattern of 18F-FDG may be separated into components reflecting perfusion and metabolism. Bevacizumab is an angiogenesis inhibitor which prevents the growth of new blood vessels, and may potentially lead to normalization of the blood circulation in the tumor. The purpose of the study was to explore the use of dynamic PET as a tool for monitoring treatment effect, reflected by changes in perfusion and metabolism. Materials and Methods. Twelve athymic nude mice, bearing the bilateral triple-negative human breast cancer xenograft MAS98.12 were treated with bevacizumab (5 mg/kg i.p.). Dynamic PET data was acquired prior to and 24 and 72 hours after treatment for 1 hour after injection of 10 MBq 18F-FDG and fitted with a FDG two-tissue compartment model. The changes in the rate constants k1, k3, MRFDG and the vascular fraction νB were assessed. To evaluate the effect of treatment regimes, 30 mice, randomized in 5 groups, received either vehicle (0.9% NaCl), bevacizumab (5 mg/kg i.p.), doxorubicin (8 mg/kg i.v.) or bevacizumab and doxorubicin either together, or doxorubicin 24 hours after bevacizumab treatment. Tumor volume was measured twice a week. Results. The perfusion-related rate parameter k1 and the metabolic rate constant k3 decreased significantly 24 hours after treatment. This decrease was followed by an increase, albeit non-significant, at 72 hours post treatment. Doxorubicin given 24 hours after bevacizumab showed less antitumor effect compared to concomitant treatment. Conclusions. Dynamic PET can detect changes in tumor perfusion and metabolism following anti-angiogenic therapy in mouse xenograft models. Longitudinal dynamic PET, used to assess the efficacy of anti-angiogenic treatment, can identify the time frame of potential tumor vasculature re-normalization and allow optimal timing of supplementary therapy (radiation or chemotherapy).