The epichaperome is an integrated chaperome network that facilitates tumour survival.

Transient, multi-protein complexes are important facilitators of cellular functions. This includes the chaperome, an abundant protein family comprising chaperones, co-chaperones, adaptors, and folding enzymes-dynamic complexes of which regulate cellular homeostasis together with the protein degradation machinery. Numerous studies have addressed the role of chaperome members in isolation, yet little is known about their relationships regarding how they interact and function together in malignancy. As function is probably highly dependent on endogenous conditions found in native tumours, chaperomes have resisted investigation, mainly due to the limitations of methods needed to disrupt or engineer the cellular environment to facilitate analysis. Such limitations have led to a bottleneck in our understanding of chaperome-related disease biology and in the development of chaperome-targeted cancer treatment. Here we examined the chaperome complexes in a large set of tumour specimens. The methods used maintained the endogenous native state of tumours and we exploited this to investigate the molecular characteristics and composition of the chaperome in cancer, the molecular factors that drive chaperome networks to crosstalk in tumours, the distinguishing factors of the chaperome in tumours sensitive to pharmacologic inhibition, and the characteristics of tumours that may benefit from chaperome therapy. We find that under conditions of stress, such as malignant transformation fuelled by MYC, the chaperome becomes biochemically 'rewired' to form a network of stable, survival-facilitating, high-molecular-weight complexes. The chaperones heat shock protein 90 (HSP90) and heat shock cognate protein 70 (HSC70) are nucleating sites for these physically and functionally integrated complexes. The results indicate that these tightly integrated chaperome units, here termed the epichaperome, can function as a network to enhance cellular survival, irrespective of tissue of origin or genetic background. The epichaperome, present in over half of all cancers tested, has implications for diagnostics and also provides potential vulnerability as a target for drug intervention.

Improved tumor imaging and therapy via i.v. IgG-mediated time-sequential modulation of neonatal Fc receptor.

The long plasma half-life of IgG, while allowing for enhanced tumor uptake of tumor-targeted IgG conjugates, also results in increased background activity and normal-tissue toxicity. Therefore, successful therapeutic uses of conjugated antibodies have been limited to the highly sensitive and readily accessible hematopoietic tumors. We report a therapeutic strategy to beneficially alter the pharmacokinetics of IgG antibodies via pharmacological inhibition of the neonatal Fc receptor (FcRn) using high-dose IgG therapy. IgG-treated mice displayed enhanced blood and whole-body clearance of radioactivity, resulting in better tumor-to-blood image contrast and protection of normal tissue from radiation. Tumor uptake and the resultant therapeutic response was unaltered. Furthermore, we demonstrated the use of this approach for imaging of tumors in humans and discuss its potential applications in cancer imaging and therapy. The ability to reduce the serum persistence of conjugated IgG antibodies after their infusion can enhance their therapeutic index, resulting in improved therapeutic and diagnostic efficacy.

Assessment of Simplified Methods for Quantification of 18F-FDHT Uptake in Patients with Metastatic Castration-Resistant Prostate Cancer.

18F-fluorodihydrotestosterone (18F-FDHT) PET/CT potentially provides a noninvasive method for assessment of androgen receptor expression in patients with metastatic castration-resistant prostate cancer (mCRPC). The objective of this study was to assess simplified methods for quantifying 18F-FDHT uptake in mCRPC patients and to assess effects of tumor perfusion on these 18F-FDHT uptake metrics. Methods: Seventeen mCRPC patients were included in this prospective observational multicenter study. Test and retest 30-min dynamic 18F-FDHT PET/CT scans with venous blood sampling were performed in 14 patients. In addition, arterial blood sampling and dynamic 15O-H2O scans were obtained in a subset of 6 patients. Several simplified methods were assessed: Patlak plots; SUV normalized to body weight (SUVBW), lean body mass (SUVLBM), whole blood (SUVWB), parent plasma activity concentration (SUVPP), area under the parent plasma curve (SUVAUC,PP), and area under the whole-blood input curve (SUVAUC,WB); and SUVBW corrected for sex hormone-binding globulin levels (SUVSHBG). Results were correlated with parameters derived from full pharmacokinetic 18F-FDHT and 15O-H2O. Finally, the repeatability of individual quantitative uptake metrics was assessed. Results: Eighty-seven 18F-FDHT-avid lesions were evaluated. 18F-FDHT uptake was best described by an irreversible 2-tissue-compartment model. Replacing the continuous metabolite-corrected arterial plasma input function with an image-derived input function in combination with venous sample data provided similar Ki results (R2 = 0.98). Patlak Ki and SUVAUC,PP showed an excellent correlation (R2 > 0.9). SUVBW showed a moderate correlation to Ki (R2 = 0.70, presumably due to fast 18F-FDHT metabolism. When calculating SUVSHBG, correlation to Ki improved (R2 = 0.88). The repeatability of full kinetic modeling parameters was inferior to that of simplified methods (repeatability coefficients > 36% vs. < 28%, respectively). 18F-FDHT uptake showed minimal blood flow dependency. Conclusion:18F-FDHT kinetics in mCRPC patients are best described by an irreversible 2-tissue-compartment model with blood volume parameter. SUVAUC,PP showed a near-perfect correlation with the irreversible 2-tissue-compartment model analysis and can be used for accurate quantification of 18F-FDHT uptake in whole-body PET/CT scans. In addition, SUVSHBG could potentially be used as an even simpler method to quantify 18F-FDHT uptake when less complex scanning protocols and accuracy are required.

Positron Emission Tomography/Computed Tomography-Based Assessments of Androgen Receptor Expression and Glycolytic Activity as a Prognostic Biomarker for Metastatic Castration-Resistant Prostate Cancer.

IMPORTANCE: Androgen receptor-signaling inhibitor (ARSi) drugs prolong life in metastatic castration-resistant prostate cancer (mCRPC), but such tumors eventually become resistant and progress. Comprehensive positron emission tomography/computed tomography (PET/CT) imaging using fluoro-2-D-deoxyglucose F 18 ([18F]-FDG) for glycolysis (Glyc) and fluorodihydrotestosterone F 18 ([18F]-FDHT) for androgen receptor (AR) expression determine heterogeneity of imaging phenotypes, which may be useful in distinguishing patients who will benefit from ARSi drugs from those who need alternative treatments. OBJECTIVE: To test the hypothesis that PET/CT-based assessments of AR expression and glycolytic activity would reveal heterogeneity affecting prognosis. DESIGN, SETTING, AND PARTICIPANTS: Between April 6, 2007, and October 4, 2012, patients with mCRPC underwent imaging with both [18F]-FDG and [18F]-FDHT at Memorial Sloan Kettering Cancer Center. The patients were naive to ARSi treatment with enzalutamide or abiraterone acetate and were referred during documented disease progression. Image-directed biopsy determined the presence or absence of prostate cancer at positive imaging sites. INTERVENTIONS: PET/CT imaging was performed with [18F]-FDHT and [18F]-FDG; select individual lesions were biopsied to correlate imaging phenotype with histologic findings. MAIN OUTCOMES AND MEASURES: All metabolically active lesions were interpreted as [18F]-FDHT-positive (AR1) or [18F]-FDHT-negative (AR0) and as [18F]-FDG-positive (Glyc1) or [18F]-FDG-negative (Glyc0). Correlation was performed with overall survival for both individual lesion imaging phenotype as well as patient-specific imaging phenotype. RESULTS: The mean (SD) age of the 133 patients was 68 (8.6) years. Imaging phenotypes of 2405 PET/CT-positive lesions (median, 12.0 per patient) included 1713 (71.2%) AR1Glyc1, 386 (16.0%) AR1Glyc0, and 306 (12.7%) AR0Glyc1. On multivariate analysis, each phenotype had an independent negative impact effect on survival, most pronounced for AR0Glyc1 lesions (hazard ratio [HR], 1.11; 95% CI, 1.05-1.16; P < .001), followed by AR1Glyc1 lesions (HR, 1.05; 95% CI, 1.03-1.06; P < .001) and AR1Glyc0 lesions (HR, 1.03; 95% CI, 1.00-1.05; P = .048). When sorted by lesion type, 4 patient-specific groups emerged: (1) concordant, with all AR1Glyc1 (34 patients [25.6%]); (2) AR predominant, with AR1Glyc1 and varying numbers of AR1Glyc0 (33 [24.8%]); (3) Glyc predominant, with AR1Glyc1 and varying numbers of AR0Glyc1 (40 [30.1%]); and (4) mixed, with AR1Glyc1 plus a mixture of varying numbers of AR1Glyc0 and AR0Glyc1 (26 [19.5%]). CONCLUSIONS AND RELEVANCE: Heterogeneity of PET/CT imaging phenotype has clinical relevance on a lesion and individual patient level. With regard to mCRPC lesions, most express ARs, consistent with initial benefit of ARSi drugs. On a patient basis, 49% (groups 3 and 4) had at least 1 AR0Glyc1 lesion-the imaging phenotype with the most negative effect on survival, possibly due to ARSi resistance.

Strategy of Using Intratreatment Hypoxia Imaging to Selectively and Safely Guide Radiation Dose De-escalation Concurrent With Chemotherapy for Locoregionally Advanced Human Papillomavirus-Related Oropharyngeal Carcinoma.

PURPOSE: To report a small substudy of an ongoing large, multi-arm study using functional imaging to assess pre-/intratreatment hypoxia for all head and neck cancer, in which we hypothesized that pre- and early-treatment hypoxia assessment using functional positron emission tomography (PET) imaging may help select which human papillomavirus (HPV)-positive (HPV(+)) oropharyngeal cancer (OPC) patients can safely receive radiation de-escalation without jeopardizing treatment outcomes. METHODS AND MATERIALS: Patients with HPV(+) oropharyngeal carcinoma were enrolled on an institutional review board-approved prospective study of which de-escalation based on imaging response was done for node(s) only. Pretreatment (18)F-fluorodeoxyglucose and dynamic (18)F-FMISO (fluoromisonidazole) positron emission tomography (PET) scans were performed. For patients with pretreatment hypoxia on(18)F-FMISO PET (defined as a >1.2 tumor to muscle standard uptake value ratio), a repeat scan was done 1 week after chemoradiation. Patients without pretreatment hypoxia or with resolution of hypoxia on repeat scan received a 10-Gy dose reduction to metastatic lymph node(s). The 2-year local, regional, distant metastasis-free, and overall survival rates were estimated using the Kaplan-Meier product-limit method. A subset of patients had biopsy of a hypoxic node done under image guidance. RESULTS: Thirty-three HPV(+) OPC patients were enrolled in this pilot study. One hundred percent showed pretreatment hypoxia (at primary site and/or node[s]), and among these, 48% resolved (at primary site and/or node[s]); 30% met criteria and received 10-Gy reduction to the lymph node(s). At the median follow-up of 32 months (range, 21-61 months), the 2-year locoregional control rate was 100%. One patient failed distantly with persistence of hypoxia on (18)F-FMISO PET. The 2-year distant metastasis-free rate was 97%. The 2-year OS rate was 100%. Hypoxia on imaging was confirmed pathologically. CONCLUSIONS: Hypoxia is present in HPV(+) tumors but resolves within 1 week of treatment in 48% of cases either at the primary site and/or lymph node(s). Our 100% locoregional control rate suggests that intratreatment functional imaging used to selectively de-escalate node(s) to 60 Gy was confirmed safe using our stringent imaging criteria. Intratreatment functional imaging warrants further study to determine its ultimate role in de-escalation treatment strategies.

Tumor localization of 16beta-18F-fluoro-5alpha-dihydrotestosterone versus 18F-FDG in patients with progressive, metastatic prostate cancer.

UNLABELLED: This trial was an initial assessment of the feasibility, in vivo targeting, and biokinetics of 16beta-(18)F-fluoro-5alpha-dihydrotestosterone ((18)F-FDHT) PET in patients with metastatic prostate cancer to assess androgen receptor expression. METHODS: Seven patients with progressive clinically metastatic prostate cancer underwent (18)F-FDG and (18)F-FDHT PET scans in addition to conventional imaging methods. Three patients had their studies repeated 1 mo later, 2 while on testosterone therapy, and the third after treatment with 17-allylamino-17-demethoxygeldanamycin (17-AAG). High-pressure liquid radiochromatography was used to separate (18)F-FDHT from radiolabeled metabolites. Lesion-by-lesion comparisons between the (18)F-FDHT, (18)F-FDG, and conventional imaging methods were performed. RESULTS: Metabolism of (18)F-FDHT was rapid, with 80% conversion within 10 min to radiolabeled metabolites that circulated bound to plasma proteins. Tumor uptake was rapid and tumor retention was prolonged. Fifty-nine lesions were identified by conventional imaging methods. (18)F-FDG PET was positive in 57 of 59 lesions (97%), with an average lesion maximum standardized uptake value (SUV(max)) = 5.22. (18)F-FDHT PET was positive in 46 of 59 lesions (78%), with the average positive lesion SUV(max) = 5.28. Treatment with testosterone resulted in diminished (18)F-FDHT uptake at the tumor site. CONCLUSION: (18)F-FDHT localizes to tumor sites in patients with progressive clinically metastatic prostate cancer and may be a promising agent to analyze antigen receptors and their impact on the clinical management of prostate cancer.

How to assess background activity: introducing a histogram-based analysis as a first step for accurate one-step PET quantification.

Many common PET segmentation methods for malignant lesions use surrounding background activity as a reference. To date, background has to be measured by drawing a second volume of interest (VOI) in nearby, undiseased tissue. This is time consuming as two VOIs have to be determined for each lesion. The aim of our study was to analyse whether background activity in different organs and body regions could be calculated from the tumour VOI by histogram analyses. The institutional review board waived informed consent for this retrospective study. For each of the following tumour types and areas - head and neck (neck), lung, hepatic metastasis (liver), melanoma (skin), and cervix (pelvis) - 10 consecutive patients with biopsy-proven tumours who underwent (18)F-fluorodeoxyglucose-PET in January 2012 were retrospectively selected. One lesion was selected and two readers drew a cubical VOI around the lesion (VOItumour) and over the background (VOIBG). The mean value of VOIBG was compared with the mode of the histogram, using equivalence testing with an equivalence margin of ±0.5 SUV. Inter-reader agreement was analysed for the mean background, and the mode of the VOItumour histogram was assessed using the concordance correlation coefficient. For both readers, the mode of VOItumour was equivalent to the mean of VOIBG (P<0.0001 for R1 and R2). The inter-reader agreement was almost perfect, with a concordance correlation coefficient of greater than 0.92 for both the mode of VOItumour and the mean of VOIBG. Background activity determined within a tumour VOI using histogram analysis is equivalent to separately measured mean background values, with an almost perfect inter-reader agreement. This could facilitate PET quantification methods based on background values without increasing workload.

Ontologizing gene-expression microarray data: characterizing clusters with Gene Ontology.

An XML-based Java application is described that provides a function-oriented overview of the results of cluster analysis of gene-expression microarray data based on Gene Ontology terms and associations. The application generates one HTML page with listings of the frequencies of explicit and implicit Gene Ontology annotations for each cluster, and separate, linked pages with listings of explicit annotations for each gene in a cluster.