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BACKGROUND AND PURPOSE: DSC-PWI has demonstrated promising results in the presurgical diagnosis of brain tumors. While most studies analyze specific parameters derived from time-intensity curves, very few have directly analyzed the whole curves. The aims of this study were the following: 1) to design a new method of postprocessing time-intensity curves, which renders normalized curves, and 2) to test its feasibility and performance on the diagnosis of primary central nervous system lymphoma. MATERIALS AND METHODS: Diagnostic MR imaging of patients with histologically confirmed primary central nervous system lymphoma were retrospectively reviewed. Correlative cases of glioblastoma, anaplastic astrocytoma, metastasis, and meningioma, matched by date and number, were retrieved for comparison. Time-intensity curves of enhancing tumor and normal-appearing white matter were obtained for each case. Enhancing tumor curves were normalized relative to normal-appearing white matter. We performed pair-wise comparisons for primary central nervous system lymphoma against the other tumor type. The best discriminatory time points of the curves were obtained through a stepwise selection. Logistic binary regression was applied to obtain prediction models. The generated algorithms were applied in a test subset. RESULTS: A total of 233 patients were included in the study: 47 primary central nervous system lymphomas, 48 glioblastomas, 39 anaplastic astrocytomas, 49 metastases, and 50 meningiomas. The classifiers satisfactorily performed all bilateral comparisons in the test subset (primary central nervous system lymphoma versus glioblastoma, area under the curve = 0.96 and accuracy = 93%; versus anaplastic astrocytoma, 0.83 and 71%; versus metastases, 0.95 and 93%; versus meningioma, 0.93 and 96%). CONCLUSIONS: The proposed method for DSC-PWI time-intensity curve normalization renders comparable curves beyond technical and patient variability. Normalized time-intensity curves performed satisfactorily for the presurgical identification of primary central nervous system lymphoma.

The genomics of primary prostate cancer differ from those of metastatic castration-resistant prostate cancer (mCRPC). We studied genomic aberrations in primary prostate cancer biopsies from patients who developed mCRPC, also studying matching, same-patient, diagnostic, and mCRPC biopsies following treatment. We profiled 470 treatment-naive prostate cancer diagnostic biopsies and, for 61 cases, mCRPC biopsies, using targeted and low-pass whole-genome sequencing (n = 52). Descriptive statistics were used to summarize mutation and copy number profile. Prevalence was compared using Fisher’s exact test. Survival correlations were studied using log-rank test. TP53 (27%) and PTEN (12%) and DDR gene defects (BRCA2 7%; CDK12 5%; ATM 4%) were commonly detected. TP53, BRCA2, and CDK12 mutations were markedly more common than described in the TCGA cohort. Patients with RB1 loss in the primary tumor had a worse prognosis. Among 61 men with matched hormone-naive and mCRPC biopsies, differences were identified in AR, TP53, RB1, and PI3K/AKT mutational status between same-patient samples. In conclusion, the genomics of diagnostic prostatic biopsies acquired from men who develop mCRPC differ from those of the nonlethal primary prostatic cancers. RB1/TP53/AR aberrations are enriched in later stages, but the prevalence of DDR defects in diagnostic samples is similar to mCRPC.

The management of advanced prostate cancer has changed substantially with the availability of multiple effective novel treatments, which has led to improved disease survival. In the era of personalized cancer treatments, more precise imaging may help physicians deliver better care. More accurate local staging and earlier detection of metastatic disease, accurate identification of oligometastatic disease, and optimal assessment of treatment response are areas where modern imaging is rapidly evolving and expanding. Next-generation imaging modalities, including whole-body MRI and molecular imaging with combined PET and CT and combined PET and MRI using novel radiopharmaceuticals, create new opportunities for imaging to support and refine management pathways in patients with advanced prostate cancer. This article demonstrates the potential and challenges of applying next-generation imaging to deliver the clinical promise of treatment breakthroughs.

CONTEXT: Patients with nonmetastatic castration-resistant prostate cancer (nmCRPC) have rising prostate-specific antigen (PSA) and castrate testosterone levels, with no radiological findings of metastatic disease on computed tomography and bone scan. Given recent drug approvals for nmCRPC, with many other therapeutics and imaging modalities being developed, management of nmCRPC is a rapidly evolving field that merits detailed investigation.OBJECTIVE: To review current nmCRPC management practices and identify opportunities for improving care of nmCRPC patients.EVIDENCE ACQUISITION: A literature search up to July 2018 was conducted, including clinical trials and clinical practice guidelines (National Comprehensive Cancer Network, European Society for Medical Oncology, European Association of Urology, Prostate Cancer Clinical Trials Working Group, Prostate Cancer Radiographic Assessments for Detection of Advanced Recurrence). Keywords included prostate cancer, nonmetastatic, castration resistance, rising PSA, and biochemical relapse.EVIDENCE SYNTHESIS: Recommendations regarding indications for, and frequency of, imaging and PSA testing, as well as for initiating systemic therapy in nmCRPC are based on PSA rise kinetics and symptoms. Both enzalutamide and apalutamide have been shown to significantly increase metastasis-free survival in phase III placebo-controlled randomised trials in nmCRPC patients with PSA doubling time (DT) ≤10 mo. The expected impact of new imaging techniques in the assessment of nmCRPC is also reviewed.CONCLUSIONS: nmCRPC is a heterogeneous disease; while observation may be an option for some patients, enzalutamide and apalutamide may be appropriate to treat nmCRPC patients with PSA-DT ≤10 mo. The emergence of more accurate imaging modalities as well as circulating tumour biomarker assays will likely redefine the assessment of nmCRPC in the near future.PATIENT SUMMARY: Herein, we review key literature and clinical practice guidelines to summarise the optimal management of patients with prostate cancer and rising prostate-specific antigen despite castrate testosterone levels, but with no evidence of distant metastasis on traditional imaging. New drugs are being developed for this disease setting; novel imaging and tumour biomarker blood tests are likely to define this disease state more accurately.

Matemàtiques i informàtica; Neurologia; Oncologia Matemáticas e informática; Neurología; Oncología Mathematics and computing; Neurology; Oncology Glioblastoma is the most common primary brain tumor. Standard therapy consists of maximum safe resection combined with adjuvant radiochemotherapy followed by chemotherapy with temozolomide, however prognosis is extremely poor. Assessment of the residual tumor after surgery and patient stratification into prognostic groups (i.e., by tumor volume) is currently hindered by the subjective evaluation of residual enhancement in medical images (magnetic resonance imaging [MRI]). Furthermore, objective evidence defining the optimal time to acquire the images is lacking. We analyzed 144 patients with glioblastoma, objectively quantified the enhancing residual tumor through computational image analysis and assessed the correlation with survival. Pathological enhancement thickness on post-surgical MRI correlated with survival (hazard ratio: 1.98, p

Objective To identify CT-acquisition parameters accounting for radiomics variability and to develop a post-acquisition CT-image correction method to reduce variability and improve radiomics classification in both phantom and clinical applications. Methods CT-acquisition protocols were prospectively tested in a phantom. The multi-centric retrospective clinical study included CT scans of patients with colorectal/renal cancer liver metastases. Ninety-three radiomics features of first order and texture were extracted. Intraclass correlation coefficients (ICCs) between CT-acquisition protocols were evaluated to define sources of variability. Voxel size, ComBat, and singular value decomposition (SVD) compensation methods were explored for reducing the radiomics variability. The number of robust features was compared before and after correction using two-proportion z test. The radiomics classification accuracy (K-means purity) was assessed before and after ComBat- and SVD-based correction. Results Fifty-three acquisition protocols in 13 tissue densities were analyzed. Ninety-seven liver metastases from 43 patients with CT from two vendors were included. Pixel size, reconstruction slice spacing, convolution kernel, and acquisition slice thickness are relevant sources of radiomics variability with a percentage of robust features lower than 80%. Resampling to isometric voxels increased the number of robust features when images were acquired with different pixel sizes (p < 0.05). SVD-based for thickness correction and ComBat correction for thickness and combined thickness–kernel increased the number of reproducible features (p < 0.05). ComBat showed the highest improvement of radiomics-based classification in both the phantom and clinical applications (K-means purity 65.98 vs 73.20). Conclusion CT-image post-acquisition processing and radiomics normalization by means of batch effect correction allow for standardization of large-scale data analysis and improve the classification accuracy. Key Points • The voxel size (accounting for the pixel size and slice spacing), slice thickness, and convolution kernel are relevant sources of CT-radiomics variability. • Voxel size resampling increased the mean percentage of robust CT-radiomics features from 59.50 to 89.25% when comparing CT scans acquired with different pixel sizes and from 71.62 to 82.58% when the scans were acquired with different slice spacings. • ComBat batch effect correction reduced the CT-radiomics variability secondary to the slice thickness and convolution kernel, improving the capacity of CT-radiomics to differentiate tissues (in the phantom application) and the primary tumor type from liver metastases (in the clinical application).

Purpose To determine the usefulness of whole-body diffusion-weighted imaging (DWI) to assess the response of bone metastases to treatment in patients with metastatic castration-resistant prostate cancer (mCRPC). Materials and Methods A phase II prospective clinical trial of the poly-(adenosine diphosphate-ribose) polymerase inhibitor olaparib in mCRPC included a prospective magnetic resonance (MR) imaging substudy; the study was approved by the institutional research board, and written informed consent was obtained. Whole-body DWI was performed at baseline and after 12 weeks of olaparib administration by using 1.5-T MR imaging. Areas of abnormal signal intensity on DWI images in keeping with bone metastases were delineated to derive total diffusion volume (tDV); five target lesions were also evaluated. Associations of changes in volume of bone metastases and median apparent diffusion coefficient (ADC) with response to treatment were assessed by using the Mann-Whitney test and logistic regression; correlation with prostate-specific antigen level and circulating tumor cell count were assessed by using Spearman correlation (r). Results Twenty-one patients were included. All six responders to olaparib showed a decrease in tDV, while no decrease was observed in all nonresponders; this difference between responders and nonresponders was significant (P = .001). Increases in median ADC were associated with increased odds of response (odds ratio, 1.08; 95% confidence interval [CI]: 1.00, 1.15; P = .04). A positive association was detected between changes in tDV and best percentage change in prostate-specific antigen level and circulating tumor cell count (r = 0.63 [95% CI: 0.27, 0.83] and r = 0.77 [95% CI: 0.51, 0.90], respectively). When assessing five target lesions, decreases in volume were associated with response (odds ratio for volume increase, 0.89; 95% CI: 0.80, 0.99; P = .037). Conclusion This pilot study showed that decreases in volume and increases in median ADC of bone metastases assessed with whole-body DWI can potentially be used as indicators of response to olaparib in mCRPC. Online supplemental material is available for this article.

Background: Mucinous colorectal carcinoma (CRC) is found in 10-20% of patients and is associated with worse prognosis and treatment resistance. The early identification of mucinous tumor component at baseline and monitoring resistant clones at follow-up is challenging in clinical practice, which hinders appropriate and timely treatment selection. At CT, being routinely acquired in clinical practice, mucinous tumors can be characterized by semantic features, such as hypoattenuation and more heterogeneous enhancement than the non-mucinous tumors (Wnorowski et al 2019). However, the diagnostic accuracy of such CT findings reaches at most 62% (Young et al 2007). This can be substantially improved by utilizing robust feature quantification using state-of-art machine learning and neural network techniques. Materials and Methods: 7 mucinous and 7 non-mucinous CRC CTs were included in the model development (80% training and 20% validation) and 2 mucinous and 2 non-mucinous independent patients were used to test the model performance. Multiple lesions (primary and metastatic) were semi-automatically segmented in 3D Slicer (N=32 development and N=12 test). Three different classification models were generated using CT images: (1) a logistic regression model based on a newly developed hypodense tissue connectivity (HTC) metric, (2) a logistic regression model using a set of automatically selected radiomics (RAD) features (shape, 1st order and 2nd order) and (3) a convolutional neural network model (CNN) based on the ResNet architecture and automatically selected features. HTC was computed as a ratio between the volume of the connected hypodense tissue (0 Citation Format: Kinga Bernatowicz, Raquel Perez Lopez, Hector Garcia Palmer, Elena Elez Fernandez, Jose Fernandez Navarro, Marta Ligero Hernandez, Alonso Garcia Ruiz, Manuel Escobar Amores. Humans cannot accurately detect mucinous colorectal carcinoma from CT images, can AI help? [abstract]. In: Proceedings of the AACR Virtual Special Conference on Artificial Intelligence, Diagnosis, and Imaging; 2021 Jan 13-14. Philadelphia (PA): AACR; Clin Cancer Res 2021;27(5_Suppl):Abstract nr PO-021.

Purpose To determine the correlation between the volume of bone metastasis as assessed with diffusion-weighted (DW) imaging and established prognostic factors in metastatic castration-resistant prostate cancer (mCRPC) and the association with overall survival (OS). Materials and Methods This retrospective study was approved by the institutional review board; informed consent was obtained from all patients. The authors analyzed whole-body DW images obtained between June 2010 and February 2013 in 53 patients with mCRPC at the time of starting a new line of anticancer therapy. Bone metastases were identified and delineated on whole-body DW images in 43 eligible patients. Total tumor diffusion volume (tDV) was correlated with the bone scan index (BSI) and other prognostic factors by using the Pearson correlation coefficient (r). Survival analysis was performed with Kaplan-Meier analysis and Cox regression. Results The median tDV was 503.1 mL (range, 5.6-2242 mL), and the median OS was 12.9 months (95% confidence interval [CI]: 8.7, 16.1 months). There was a significant correlation between tDV and established prognostic factors, including hemoglobin level (r = -0.521, P < .001), prostate-specific antigen level (r = 0.556, P < .001), lactate dehydrogenase level (r = 0.534, P < .001), alkaline phosphatase level (r = 0.572, P < .001), circulating tumor cell count (r = 0.613, P = .004), and BSI (r = 0.565, P = .001). A higher tDV also showed a significant association with poorer OS (hazard ratio, 1.74; 95% CI: 1.02, 2.96; P = .035). Conclusion Metastatic bone disease from mCRPC can be evaluated and quantified with whole-body DW imaging. Whole-body DW imaging-generated tDV showed correlation with established prognostic biomarkers and is associated with OS in mCRPC. (©) RSNA, 2016 Online supplemental material is available for this article.

Purpose: We evaluated whether next-generation sequencing (NGS) of circulating cell-free DNA (cfDNA) could be used for patient selection and as a tumor clone response biomarker in patients with advanced cancers participating in early-phase clinical trials of targeted drugs. Experimental Design: Plasma samples from patients with known tumor mutations who completed at least two courses of investigational targeted therapy were collected monthly, until disease progression. NGS was performed sequentially on the Ion Torrent PGM platform. Results: cfDNA was extracted from 39 patients with various tumor types. Treatments administered targeted mainly the PI3K–AKT–mTOR pathway (n = 28) or MEK (n = 7). Overall, 159 plasma samples were sequenced with a mean sequencing coverage achieved of 1,685X across experiments. At trial initiation (C1D1), 23 of 39 (59%) patients had at least one mutation identified in cfDNA (mean 2, range 1–5). Out of the 44 mutations identified at C1D1, TP53, PIK3CA and KRAS were the top 3 mutated genes identified, with 18 (41%), 9 (20%), 8 (18%) different mutations, respectively. Out of these 23 patients, 13 received a targeted drug matching their tumor profile. For the 23 patients with cfDNA mutation at C1D1, the monitoring of mutation allele frequency (AF) in consecutive plasma samples during treatment with targeted drugs demonstrated potential treatment associated clonal responses. Longitudinal monitoring of cfDNA samples with multiple mutations indicated the presence of separate clones behaving discordantly. Molecular changes at cfDNA mutation level were associated with time to disease progression by RECIST criteria. Conclusions: Targeted NGS of cfDNA has potential clinical utility to monitor the delivery of targeted therapies. Clin Cancer Res; 21(20); 4586–96. ©2015 AACR.

3541 Background: So far, no biomarkers of response to anti-angiogenic drugs are available in colorectal cancer (CRC) treatment. Liquid biopsy tracks dynamic mutational changes in CRC patients (pts). RAS mutant allele fraction in plasma (plMAF) is an independent prognostic marker in metastatic CRC (mCRC). We explored the predictive value of plMAF in RAS mutant pts treated in 1st line with chemotherapy +/- bevacizumab (bev). Methods: A multicentric prospective/retrospective analysis was conducted. We collected data from 226 mCRC pts and selected the subset not eligible for metastasis resection with basal plMAF sample evaluable for RAS mutant MAF quantification with digital PCR (BEAMing). Pts were stratified as high (≥ 5.8%) or low ( < 5.8%) plMAF. We investigated associations between clinicopathological variables and progression-free survival (PFS) stratified by plMAF RAS levels using Cox regression models and survival data were calculated by Kaplan-Meier method. Computational analysis of baseline CT scan data extracted 93 radiomics features of all the lesions per patient including 1) 1st class from density histogram distribution and texture analysis by 2) 2nd order and 3) higher order feature classes. The radiomic features distribution between pts with high and low pIMAF was assessed with Student’s t-test analysis. Results: From October 17 to May 19, 63 basal plasma samples were analysed with BEAMing. 42 pts (67.7%) were classified as high and 21 pts (32,3%) as low plMAF. In high plMAF subgroup, a statistically significant longer PFS favouring FOLFOX+bev was observed, compared to FOLFOX alone (10.7 vs 6.9 mts; HR: 0.30; p = 0.002). In low RAS plMAF subgroup, no differences in terms of PFS were observed in either arm (8.9 vs 8.7 mts; HR: 0.7; p = 0.6). Multivariate PFS model showed no association between RAS plMAF and clinicopathological variables, except for high RAS plMAF and treatment benefit with FOLFOX+bev. The CT-radiomics signature, that may translate tumor vascularization, differentiated patients with high vs low pIMAF (p = 0.002). 58 patients (92%) had similar radiomic score; 5 patients with high plMAF (8%) presented very heterogeneous radiomic score distribution. Conclusions: Tumor-borne RAS plMAFs may constitute a potential predictive biomarker of efficacy for anti-angiogenic drugs in mCRC. Next steps will include the identification of -histological, transcriptomic and radiomic- surrogate biomarkers of response that reflect tumor irrigational status.

Purpose: CHD1 deletions and SPOP mutations frequently cooccur in prostate cancer with lower frequencies reported in castration-resistant prostate cancer (CRPC). We monitored CHD1 expression during disease progression and assessed the molecular and clinical characteristics of CHD1-deleted/SPOP-mutated metastatic CRPC (mCRPC). Experimental Design: We identified 89 patients with mCRPC who had hormone-naive and castration-resistant tumor samples available: These were analyzed for CHD1, PTEN, and ERG expression by IHC. SPOP status was determined by targeted next-generation sequencing (NGS). We studied the correlations between these biomarkers and (i) overall survival from diagnosis; (ii) overall survival from CRPC; (iii) duration of abiraterone treatment; and (iv) response to abiraterone. Relationship with outcome was analyzed using Cox regression and log-rank analyses. Results: CHD1 protein loss was detected in 11 (15%) and 13 (17%) of hormone-sensitive prostate cancer (HSPC) and CRPC biopsies, respectively. Comparison of CHD1 expression was feasible in 56 matched, same patient HSPC and CRPC biopsies. CHD1 protein status in HSPC and CRPC correlated in 55 of 56 cases (98%). We identified 22 patients with somatic SPOP mutations, with six of these mutations not reported previously in prostate cancer. SPOP mutations and/or CHD1 loss was associated with a higher response rate to abiraterone (SPOP: OR, 14.50 P = 0.001; CHD1: OR, 7.30, P = 0.08) and a longer time on abiraterone (SPOP: HR, 0.37, P = 0.002, CHD1: HR, 0.50, P = 0.06). Conclusions: SPOP-mutated mCRPCs are strongly enriched for CHD1 loss. These tumors appear highly sensitive to abiraterone treatment. Clin Cancer Res; 24(22); 5585–93. ©2018 AACR.

Primary malignant brain tumours (PMBT) constitute less than 2% of all malignancies and carry a dismal prognosis. Treatment options at relapse are limited. First-in-human solid tumour studies have historically excluded patients with PMBT due to the poor prognosis, concomitant drug interactions and concerns regarding toxicities. Retrospective data were collected on clinical and tumour characteristics of patients referred for consideration of Ph1 trials in the Royal Marsden Hospital between June 2004 and August 2016. Survival analyses were performed using the Kaplan–Meier method, Cox proportional hazards model. Chi squared test was used to measure bivariate associations between categorical variables. 100pts with advanced PMBT were referred. At initial consultation, patients had a median ECOG PS 1, median age 48 years (range 18–70); 69% were men, 76% had glioblastoma; 68% were on AEDs, 63% required steroid therapy; median number of prior treatments was two. Median OS for patients treated on a Ph1 trials was 9.3 months (95% CI 5.9–12.9) versus 5.3 months (95% CI 4.1–6.1) for patients that did not proceed with a Ph1 trial, p = 0.0094. Steroid use, poor PS, neutrophil-to-lymphocyte ratio and treatment on a Ph1 trial were shown to independently influence OS. We report a survival benefit for patients with PMBT treated on Ph1 trials. Toxicity and efficacy outcomes were comparable to the general Ph1 population. In the absence of an internationally recognized standard second line treatment for patients with recurrent PMBT, more Ph1 trials should allow enrolment of patients with refractory PMBT and Ph1 trial participation should be considered at an earlier stage.

Until 2010, docetaxel was the only agent with proven survival benefit for castration-resistant prostate cancer. The development of cabazitaxel, abiraterone acetate, enzalutamide, radium-223, and sipuleucel-T has increased the number of treatment options. Because these agents were developed concurrently within a short period of time, prospective data on their sequential use efficacy are scarce. The challenge now is to reach a consensus on the best way to sequence effective treatments, ideally by the use of an approach specific to patient subgroups. However, the absence of robust surrogates of survival and the lack of predictive biomarkers makes data for the sequential use of these agents difficult to obtain and interpret.

SummaryToward development of a precision medicine framework for metastatic, castration-resistant prostate cancer (mCRPC), we established a multi-institutional clinical sequencing infrastructure to conduct prospective whole-exome and transcriptome sequencing of bone or soft tissue tumor biopsies from a cohort of 150 mCRPC affected individuals. Aberrations of AR, ETS genes, TP53, and PTEN were frequent (40%–60% of cases), with TP53 and AR alterations enriched in mCRPC compared to primary prostate cancer. We identified new genomic alterations in PIK3CA/B, R-spondin, BRAF/RAF1, APC, β-catenin, and ZBTB16/PLZF. Moreover, aberrations of BRCA2, BRCA1, and ATM were observed at substantially higher frequencies (19.3% overall) compared to those in primary prostate cancers. 89% of affected individuals harbored a clinically actionable aberration, including 62.7% with aberrations in AR, 65% in other cancer-related genes, and 8% with actionable pathogenic germline alterations. This cohort study provides clinically actionable information that could impact treatment decisions for these affected individuals.

Aim To test the hypothesis that computed tomography (CT)-based signs might precede symptomatic malignant spinal cord compression (MSCC) in men with metastatic castration-resistant prostate cancer (mCRPC). Materials and methods A database was used to identify suitable mCRPC patients. Staging CT images were retrospectively reviewed for signs preceding MSCC. Signs of malignant paravertebral fat infiltration and epidural soft-tissue disease were defined and assessed on serial CT in 34 patients with MSCC and 58 control patients. The presence and evolution of the features were summarized using descriptive statistics. Results In MSCC patients, CT performed a median of 28 days prior to the diagnostic magnetic resonance imaging (MRI) demonstrated significant epidural soft tissue in 28 (80%) patients. The median time to MSCC from a combination of overt malignant paravertebral and epidural disease was 2.7 (0–14.6) months. Conversely, these signs were uncommon in the control cohort. Conclusions Significant malignant paravertebral and/or epidural disease at CT precede MSCC in up to 80% of mCRPC patients and should prompt closer patient follow-up and consideration of early MRI evaluation. These CT-based features require further prospective validation.

Background: CTEPH is one of the leading causes of severe pulmonary hypertension and can be devastating for those individuals who are affected. The exact incidence of CTEPH after a PE is debated depending on patient selection as well as CTEPH diagnostic criteria. Aim: To determine the incidence for CTEPH at six monyhs of a PE. Methods: A prospective study was conducted in 17 Spanish hospitals. All consecutive PE patients were recruited and followed-up according to a standarized set of clinical questions. Symptomatic patients underwent a structured evaluation with echocardiography and complete work-up for CTEPH. Results: 1065 patients were recruited from April of 2014. 1026 patients completed the follow-up until 6 months, 52% were males. There were significant differences in mean ages between males (63.8±14.7 years) and females (67.2±17.1 years) (p=0.001). Patients were haemodinamically unstable at PE diagnosis in 9%, cancer-associated-PE in 20%, incidental PE in 14% and with previous thromboembolic diseases in 12%. CTEPH with pathological imaging and a mean pulmonary artery pressure (mPAP) ≥25 mmHg at rest was confirmed in seven subjects; accumulated incidence of 6.82‰[CI95%: 2.74-14.0]. Conclusions: Accumulated incidence at 6 months after a PE was infrequent. Only the fourth part of patients who reparted symptons had CTEPH diagnostic criteria. Acknowledgment to Angelica Martin and Tania Jimenez (S-H Medical) for your support, and to Bayer Heathcare for partial funding.

1075 Background: NGS in ctDNA from MBC is feasible and results may be informative for patients’ management, especially in non-luminal tumors (Oliveira et al, ASCO 2018). We aimed to study the determinants of concordance in CRG in a cohort of 60 MBC patients undergoing tBx and ctDNA collection. Methods: MiSeq Amplicon-based NGS (59 cancer-related genes) was performed in one single metastatic lesion per patient and compared with liquid biopsies taken at the same time point at disease progression to prior treatment. The concordance in CRG ( PIK3CA, AKT1, ERBB2, ESR1, PTEN, BRAF, FGFR1, HRAS, KRAS, and PIK3R1) in tBx vs ctDNA was determined at patient and at mutation (mut) level and correlated with mutant allele fraction (MAF), total disease volume (TDV), and clinical characteristics. True positive in plasma (TPP): patient with a mut detected both in ctDNA and tBx. TDV was defined as all metastasis volume assessed by CT scan (excluding sclerotic bone metastasis), and analyzed by an experienced radiologist using the 3DSlicer semiautomatic segmentation tool (TDV = pixel size x number of pixels). Results: Concordance in CRG at patient and mut level was 72% and 55%, respectively. Concordance for ERBB2 (1/1; 100%) and PIK3CA (17/22; 77%) was higher than for ESR1 (8/20; 40%) and AKT1 (2/6; 33%). ctDNA failed to detect 14 mut present in tBx ( ESR1 n = 5, PIK3CA n = 5, AKT1 n = 3, BRAF n = 1). Concordance was 100% for non-luminal and 60% for luminal cases (P = 0.01). In univariate analysis, concordance was not associated with MAF in tBx (P = 0.15), TDV (p = 0.86), number of prior lines of therapy (P = 0.57), number of metastatic sites (P = 0.56) or presence of visceral metastasis (P = 1.0). In patients with PIK3CA mut (N = 22), those with TPP had a numerically higher TDV than those where a PIK3CA mut was not detected in ctDNA (20.9cm3 vs 5.1cm3, P = 0.28). Across all patients, in the multivariate logistic model adjusted for other factors, TDV was a determinant of TPP (OR 1.02, 95%CI 1.0-1.06; P = 0.059). For each increase of 1cm3 in TDV, there was a 2% increase in the probability of detecting a mut in ctDNA. Conclusions: Our results suggest that liquid biopsy testing for the detection of actionable CRG is clinically valid in MBC, although its yield depends on several factors – tumor subtype, analyzed gene, and possibly tumor volume – that reflect both tumor heterogeneity and tumor shedding rate. Due to the potential clinical implications, the observation that mutation detection in ctDNA may correlate with tumor volume merits further study in a larger dataset.

448 Background: Hyperprogressive disease (HPD) is a new pattern of progression in cancer patients (pts) treated with immune checkpoint inhibitors (ICI). The rate and outcome of HDP in pts with metastatic renal carcinoma (RCC) and urothelial carcinoma (UC) are unknown. Here, we report the percentage of HPD in a cohort of pts with GU malignancies treated at our center and explore associations with clinical variables. Methods: Medical records from pts treated in phase I-III clinical trials with ICI alone or in combination between July 2013 and June 2018 were retrospectively reviewed. We defined HPD according to the radiologic VHIO´s criteria (ASCO 2018). Associations between HPD and categorical or continuous variables were evaluated using Fisher exact test and Wilcoxon test respectively. OS were estimated with the Kaplan-Meir method. Statistical analyses were performed using the R statistical software (R version 3.5.0). Results: Overall, 104 pts received therapy with ICI. Of these patients, 16 were not included for the analysis (6 pts with absence of measurable disease, 6 pts did not have CT scan available after the clinical progression and 4 pts treated with ICI plus chemotherapy). Thus, 88 pts were included for the analysis, 29 (33%) with RCC and 59 (67%) with UC. Median follow-up was 7.4 months. Median age was 66.5 years (range 29-91 y).Twenty-three pts (26%) were treated with ICI monotherapy and 65 pts (74%) in combination (anti-CTL4, antiangiogenics, PARP inhibitors, FGFR inhibitors). Forty-seven pts (53%) received ICI as second-line therapy or later. By RECIST v1.1, 26 (30%), 19 (21%) and 43(49%) pts had a best response of progressive disease, stable disease or partial+complete response, respectively. We identified 9 pts (10%) who meet the HPD criteria, 2 pts with RCC and 7 with UC. HPD was associated with anemia at baseline (p = 0.058). Pts with HPD had a trend toward lower overall survival (OS) compared with pts with non-HPD (8.87 vs 4.77 months; p = 0.065). Conclusions: These findings demonstrate that HPD is a phenomenon seen in a significant proportion of pts with RCC and UC and should be taken in account. We found that HPD is associated with poor OS and the anemia at baseline was correlated with HPD.

Micro-Abstract We analyzed 115 iliac crest bone marrow biopsy specimens from 101 patients with metastatic castration-resistant prostate cancer, divided into a test (n = 57) and a validation (n = 58) set. We developed a score based on computed tomography Hounsfield units and lactate dehydrogenase levels, which were associated with a positive biopsy result. The score can be used to select patients for whom a bone marrow biopsy will provide tissue for molecular characterization., Background The urgent need for castration-resistant prostate cancer molecular characterization to guide treatment has been constrained by the disease's predilection to metastasize primarily to bone. We hypothesized that the use of clinical and imaging criteria could maximize tissue acquisition from bone marrow biopsies (BMBs). We aimed to develop a score for the selection of patients undergoing BMB. Materials and Methods A total of 115 BMBs were performed in 101 patients: 57 were included in a derivation set and 58 were used as the validation set. The clinical and laboratory data and prebiopsy computed tomography parameters (Hounsfield units [HUs]) were determined. A score for the prediction of biopsy positivity was developed from logistic regression analysis of the derivation set and tested in the validation set. Results Of the 115 biopsy specimens, 75 (62.5%) were positive; 35 (61.4%) in the test set and 40 (69%) in the validation set. On univariable analysis, hemoglobin (P = .019), lactate dehydrogenase (P = .003), prostate-specific antigen (P = .005), and mean HUs (P = .004) were selected. A score based on the LDH level (≥ 225 IU/L) and mean HUs (≥ 125) was developed in multivariate analysis and was associated with BMB positivity in the validation set (odds ratio, 5.1; 95% confidence interval, 1.9%-13.4%; P = .001). The area under the curve of the score was 0.79 in the test set and 0.77 in the validation set. Conclusion BMB of the iliac crest is a feasible technique for obtaining tumor tissue for genomic analysis in patients with castration-resistant prostate cancer metastatic to the bone. A signature based on the mean HUs and LDH level can predict a positive yield with acceptable internal validity. Prospective studies of independent cohorts are needed to establish the external validity of the score.

BACKGROUND Prostate cancer is a heterogeneous disease, but current treatments are not based on molecular stratification. We hypothesized that metastatic, castration-resistant prostate cancers with DNA-repair defects would respond to poly(adenosine diphosphate [ADP]-ribose) polymerase (PARP) inhibition with olaparib. METHODS We conducted a phase 2 trial in which patients with metastatic, castration-resistant prostate cancer were treated with olaparib tablets at a dose of 400 mg twice a day. The primary end point was the response rate, defined either as an objective response according to Response Evaluation Criteria in Solid Tumors, version 1.1, or as a reduction of at least 50% in the prostate-specific antigen level or a confirmed reduction in the circulating tumor-cell count from 5 or more cells per 7.5 ml of blood to less than 5 cells per 7.5 ml. Targeted next-generation sequencing, exome and transcriptome analysis, and digital polymerase-chain-reaction testing were performed on samples from mandated tumor biopsies. RESULTS Overall, 50 patients were enrolled; all had received prior treatment with docetaxel, 49 (98%) had received abiraterone or enzalutamide, and 29 (58%) had received cabazitaxel. Sixteen of 49 patients who could be evaluated had a response (33%; 95% confidence interval, 20 to 48), with 12 patients receiving the study treatment for more than 6 months. Next-generation sequencing identified homozygous deletions, deleterious mutations, or both in DNA-repair genes - including BRCA1/2, ATM, Fanconi's anemia genes, and CHEK2 - in 16 of 49 patients who could be evaluated (33%). Of these 16 patients, 14 (88%) had a response to olaparib, including all 7 patients with BRCA2 loss (4 with biallelic somatic loss, and 3 with germline mutations) and 4 of 5 with ATM aberrations. The specificity of the biomarker suite was 94%. Anemia (in 10 of the 50 patients [20%]) and fatigue (in 6 [12%]) were the most common grade 3 or 4 adverse events, findings that are consistent with previous studies of olaparib. CONCLUSIONS Treatment with the PARP inhibitor olaparib in patients whose prostate cancers were no longer responding to standard treatments and who had defects in DNA-repair genes led to a high response rate. (Funded by Cancer Research UK and others; ClinicalTrials.gov number, NCT01682772; Cancer Research UK number, CRUK/11/029.)

218 Background: CRPC is enriched for germline mutations in DNA damage repair genes (gDDRm). BRCA2 mutations (g BRCA2m) associate with poor prognosis from localized PC, but prognostic and predictive value for standard therapy in CRPC is unclear. We reviewed clinical outcome of 390 patients previously tested for gDDRm. Methods: Patient records were reviewed for 372 patients from 3 institutions (Royal Marsden UK, Weill-Cornell NY, University of Washington, WA) with gDDRm status previously published (Pritchard et al, NEJM 2016) and 18 g BRCA1/2m carriers from KConFab consortium (Australia). Baseline characteristics and survival were annotated. Response (PSA50%/RECIST) and PFS (RECIST/PSA progression or start of a new therapy due to clinical progression) were collected for Abiraterone, Enzalutamide and Docetaxel. To account for potential differences between cohorts, a mixed effect model (Weibull distribution) with random intercept per cohort was pursued. Results: dDDRm status was available for n = 390 (60 gDDRm+, including 37 g BRCA2m, and 330 gDDRm-). Overall, 74% and 69% received Docetaxel and Abiraterone/Enzalutamide respectively; 47% gDDRm+ and 34% gDDRm- received PARPi and/or platinum. Median overall survival from CRPC was 3.0 vs 3.2 years in gDDRm+ vs gDDRm- (p = 0.73; g BRCA2m = 3.0 years, p = 0.72). Age and Gleason score at diagnosis were associated with survival from castration-resistance in multivariate analysis. Median PFS on Docetaxel for gDDRm+ (6.8 months; 6.3 for g BRCA2m) and gDDRm- (5.1 months) were not significantly different (p = 0.2). Similarly, RR to Docetaxel was similar for the two groups (61% vs 54% in gDDRm+ vs gDDRm-; 63% g BRCA2m). Median PFS and RR on first Abiraterone/Enzalutamide were similar across groups (PFS: 8.3 months gDDRm+, 8.3 months for gDDRm-; p = 0.9; RR 46% vs 56% respectively) The Interaction of PARPi/platinum therapy among gDDRm+ patients resulted in an aHR for OS from CRPC of 0.59 (95%CI 0.28-1.25; p = 0.17). Conclusions: In this retrospective analysis, CRPC patients with gDDRm still benefited from standard therapies similarly to non-mutation carriers; interpretation of survival data should consider the high proportion treated with PARPi/platinum.

5071 Background: An urgent need exists for new therapies after progression (PD) onAA and enzalutamide (ENZ). Increased PR expression or progesterone-activating AR mutations have been associated with resistance to AR targeting. We aimed to test ONA, a type I PR antagonist with clinical activity in PRpos cancers, in AA/enz-resistant CRPC. In a prospectively defined exploratory analysis, we aimed to report outcome by plasma AR status ( pAR). Methods: This was a multi-institution, open label phase I/II clinical trial in pts progressing after ENZ/AA. Pts were first treated with single agent (SA) ONA using a randomised dose escalation design. ONA at 2 doses was then combined with AA (1000mg od with pred 5mg bid) in pts progressing on AA. The primary end-points were safety, pharmacokinetics (PK) and anti-tumor activity split by p AR. Archival and metastatic biopsies were collected when possible and tested for PR status. p AR was studied using previous methods (Romanel STM 2015). Results: 21 pts received SA ONA (5 = 10mg/ 5 = 20mg/ 4 = 30mg/ 4 = 40mg /3 = 50mg BID) and 15 pts received ONA-AA combination (5 = 30mg ONA BID, 10 = 50mg ONA BID). There were not DLTs or significant LFT abnormalities and no G3/4 adverse events (AE), no treatment discontinuations due to AEs and no SAEs considered related to ONA. PK in SA ONA observed active plasma concentrations and no interaction with AA. Of 32 evaluated pts 15 had a 2105T > A (p.L702H) or 2632A > G (p.T878A) AR mutation detected in plasma pre-treatment and 1 had AR copy number gain. PSA declines were not observed with SA ONA but in 2 pts with combination (-30%, -7%) who were AR normal. The rPFS on SA ONA was 2.8 months for AR normal and 2.6 for AR aberrant (Hazard ratio (HR) 1.41; 95% CI, 0.62-3.72; P 0.48) and on combination was 4.4 months for AR normal (8/15) and 2.2 for AR aberrant (7/15) (HR 6.08; 95%CI, 6.32-221.9; P < 0.001). Conclusions: ONA is safe in CRPC as SA and in combination with AA. There was no difference in rPFS by p AR status for SA ONA but on the combination with AA, pts who were plasma AR normal had a significantly longer rPFS. Clinical trial information: NCT02049190.

INTRODUCTION: Response assessment of bone metastases (BM) remains a challenge for drug development in metastatic castration resistant prostate cancer (mCRPC) as standard imaging techniques, computed tomography and bone scintigraphy, fail to characterize BM. Diffusion-weighted imaging (DWI) is a functional MRI technique that studies the motion of water molecules within a tissue informing on cellularity. We hypothesized that changes in whole body (WB) DWI informs on BM response to treatment in mCRPC. METHODS: We conducted a phase II trial of the PARP inhibitor olaparib in mCRPC (TOPARP-A; CRUK/11/029); the primary endpoint was response rate defined using RECIST 1.1, PSA falls of ≥50% and conversion of circulating tumour cell (CTC) counts from ≥5 to RESULTS: Overall, 33/42 pt consented to the WB-DWI substudy of whom 21 had WB-DWI at baseline and at 12w. Of these 29% (6/21) were classified as responders to olaparib as per the primary endpoint definition and had not progressed prior to 12w. At baseline, median CTC count was 46 CTC/7.5ml blood and median PSA was 411 ng/ml for this cohort. When assessing all the areas of DWI signal abnormality, median volume of BM per patient was 445ml and mADC was 782 x10-6 mm2/s. Baseline CTC counts and PSA were significantly associated with volume of BM (ρ = 0.59, p = 0.005; ρ = 0.64, p = 0.002 respectively). All pts who responded to olaparib showed a decrease in volume of BM (median -41.1%, range -58.8%, -6.3%), whilst in non-responders a decrease was not observed in any pt (median 20.7%, range 0.0%, 76.9%); the difference between responders and non-responders was statistically significant (p = 0.001). Increases in mADC after 12 weeks of treatment were associated with increased odds of response (Odds Ratio: 1.08, 95% CI 1.00, 1.15, p = 0.04). Additionally, we detected a significant positive association between changes in volume of BM estimated by DWI and best percentage change in PSA and CTC (ρ = 0.63, p = 0.002 and ρ = 0.77, p CONCLUSION: Decrease in volume and increase in mADC of BM assessed by WB-DWI are indicators of response to olaparib in BM from mCRPC. These data require validation but support the use of WB-DWI for assessing BM during treatment. Citation Format: Raquel Perez-Lopez, Matthew D. Blackledge, Helen Mossop, Joaquin Mateo, David Collins, Veronica A. Morgan, Alison McDonald, Shahneen Sandhu, Aurelius Omlin, Diletta Bianchini, Zafeiris Zafeiriou, Pasquale Rescigno, Michael Kolinsky, Daniel Nava Rodrigues, Penny Flohr, Berni Ebbs, Gemma Fowler, Nuria Porta, Emma Hall, Martin Leach, Johann S. de Bono, Dow-Mu Koh, Nina Tunariu. Diffusion-weighted imaging of bone metastases as treatment response biomarker in prostate cancer. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3973.

2043Background: Malignant primary CNS tumors constitute less than 2% of all malignancies and carry a dismal prognosis. Treatment (tx) options at relapse are limited. First-in-human solid tumor stud...

5028Background: Recent data show that 20-30% of mCRPC patients have defects in DNAr genes. We have evaluated the clinical phenotype of these patients. Methods: Medical records of mCRPC patients tre...

e13515Background: Molecular alterations in GBM, might better explain than morphology or clinical factors, differences in outcome and response to treatment. Multiple data integration an homogeneous ...

2504Background: ATR is a regulator of cellular responses to replication stress, where it signals DNA damage repair by homologous recombination. Many cells depend on ATR to survive DNA damage. VX-970 is a potent, selective ATR inhibitor with marked preclinical antitumor activity in combo with chemotherapy. Methods: Patients (pts) with advanced cancers were enrolled in 2 parts. Part A: N=1 pt cohorts received VX-970 QW; 3 + 3 cohorts were commenced if ³ G2 drug-related toxicities occurred. Part B: 3 + 3 pt cohorts received CP on d1 + VX-970 on d2 and 9 in 21-day cycles. Timed pre- and post-VX-970 tumor biopsies were assessed for pS345 CHK1 levels by IHC in part B. Hematologic toxicities were modeled for pts in part B. Results: 26 pts were treated; M/F 10/16, ECOG PS 0/1: 9/17. Median age: 66 yrs (range 49-76 years). VX-970 was generally well tolerated as mono or CP combo with mainly G1-2 toxicities. CP dose delays and reductions occurred in 3/3 pts (B1); 2/2 pts (B2); 0/3 pts (B3); 1/6 pts (B4) due to neutr...

Background: ATR mediates the homologous recombination DNA repair pathway and cellular response to replication stress. VX-970 is a potent and selective inhibitor of ATR (Ki Methods: Pts with advanced solid tumors enrolled in 2 sequential parts. Part A: pts received IV VX-970 mono weekly in single-pt cohorts, with 3+3 cohorts initiated if grade (G) ≥2 VX-970-related adverse events (AEs) were observed. Part B: pts received CP on day 1 and VX-970 on days 2 and 9 of a 21-day cycle in a 3+3 dose-escalation design. Paired VX-970 tumor biopsies were obtained in selected CP treated pts pre- and post-VX-970, and pS345 Chk1 levels assessed by IHC. Results: 25 pts were treated; M/F 10/15; median age 67 yr (range 49-76 yr); ECOG PS 0/1: 11/14. In Part A, 11 pts (colorectal [CRC; n = 2]; mesothelioma [n = 2]; other [n = 7]; median prior lines of therapy = 3) received VX-970 at 60 mg/m2 (n = 1), 120 mg/m2 (n = 2), 240 mg/m2 (n = 1) and 480 mg/m2 (n = 7). In Part B, 14 pts (CRC [n = 6]; ovarian [n = 2]; other [n = 6]; median prior lines of therapy = 3) received VX-970 240 mg/m2 + CP AUC5 (n = 3; dose level 1 [DL1]), VX-970 120 mg/m2 + CP AUC5 (n = 3; DL2), VX-970 120 mg/m2 + CP AUC4 (n = 3; DL3) and VX-970 90 mg/m2 + CP AUC5 (n = 5; DL4). In Part A, no dose-limiting toxicities (DLT) or drug-related G3-4 AEs were seen. In Part B, 2 pts had DLT: G4 neutropenia and fever (n = 1; DL1) and G3 hypersensitivity (n = 1; DL2). Non-DLT G3-4 AEs were neutropenia (n = 4; DL1-2) and thrombocytopenia (n = 1; DL2) requiring dose delays. No G3-4 AEs were seen at DL3-4. RP2D cohort expansion is ongoing at DL4. VX-970 displayed linear AUC and Cmax at all DLs; median half-life was 16h with no accumulation. Based on preclinical models, efficacious exposures were achieved. When combined with CP, DL1 and DL2 showed similar VX-970 exposure, suggesting no apparent drug interactions. Decreased Chk1 phosphorylation was seen in 2/2 paired tumor biopsies (74% at DL4; 94% at DL2). An advanced CRC pt (serosal disease and abdominal lymphadenopathy; 3 prior lines of chemotherapy) with complete ATM loss by IHC achieved RECIST complete response to VX-970 mono at 60 mg/m2 and remains on trial at 59+ wks. RECIST stable disease (SD) was seen with VX-970 mono in 4 pts (median duration of SD = 11 wks [11-17.4 wks]) and VX-970 + CP in 7 pts, who were still ongoing (duration of SD = 5+ to 20+ wks), including several pts who had progressed on prior platinum therapy. Conclusion: VX-970 is well tolerated as monotherapy and in combination with CP, with preliminary evidence of target modulation and antitumor activity. VX-970 will be further explored in early phase II studies; in multiple tumor types, including triple-negative breast cancer and non-small cell lung cancer; and in patients with DDR aberrations. Citation Format: Timothy A. Yap, Maria J. de Miguel Luken, Brent O'Carrigan, Desam Roda, Dionysis Papadatos-Pastos, David Lorente, Nina Tunariu, Raquel Perez Lopez, Sasha Gayle, Ruth Riisnaes, Ines Figueiredo, Susana Miranda, Suzanne Carreira, Fang Yang, Sharon Karan, Marina Penney, John Pollard, L. Rhoda Molife, Udai Banerji, Mohammed Asmal, Scott Z. Fields, Johann S. de Bono. Phase I trial of first-in-class ataxia telangiectasia-mutated and Rad3-related (ATR) inhibitor VX-970 as monotherapy (mono) or in combination with carboplatin (CP) in advanced cancer patients (pts) with preliminary evidence of target modulation and antitumor activity. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2015 Nov 5-9; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2015;14(12 Suppl 2):Abstract nr PR14.

Introduction The Neuropsychiatric Inventory (NPI) is a scale that assesses psychiatric symptoms in patients with neurological disorders, principally dementia. Despite its advantages, there are few published studies in traumatic brain injury (TBI) patients. With the NPI information we are going to describe the psychopathologic disorders in a group of TBI chronic patients and look for the possible association with psychiatric history and outcome measures. Method The NPI was applied to caregivers of 53 patients with severe TBI in chronic phase. We also collected functional and community integration scales. Results 92.5% of patients had some neuropsychiatric symptoms, according to NPI. The most frequent were irritability/lability, apathy and depression/dysphoria. Those patients with drugs abuse history had more psychiatric symptoms. Presence of agitation/aggression, apathy and disinhibition were correlated with more disabilities. Conclusions Psychiatric disorders are common among patients with TBI. The NPI is a scale that systematically assesses the behavioural and emotional disorders more common in these patients. Some of the symptoms negatively influence the degree of disability.

Introduction: Next generation sequencing (NGS) has identified genomic aberrations causing DNA repair defects in sporadic metastatic castration resistant prostate cancer (mCRPC). We hypothesized that single agent olaparib would have antitumor activity in a sub-population of mCRPC patients (pts) and that exome and transcriptome studies would identify this population. Methods: TOPARP is an open-label, investigator-initiated phase II trial with a novel multi-step adaptive design (CRUK/11/029). The first part of the study (TOPARP-A) has a two-stage design evaluating the antitumor activity of single agent olaparib in unselected mCRPC pts (p0 = 0.05; p1 = 0.20; α = 0.02; β = 0.10) with a preplanned analysis to identify a biomarker defined sensitive subgroup. Primary endpoint, response rate (RR), was defined as objective response by RECIST 1.1 and/or PSA fall ≥50% and/or confirmed circulating tumor cell (CTC) count falls from ≥5 to Results: Fifty pts were enrolled from 7 UK centers; all had had prior docetaxel, 48 (96%) prior abiraterone and 29 (58%) prior cabazitaxel. Overall, 16 of 49 evaluable pts experienced a response (RR 32.7%, 95% CI: 20.0 to 47.5), with 11 and 4 pts having been on treatment for >6 and >12 months respectively at data cut-off. NGS identified homozygous deletions and/or putatively deleterious mutations in DNA repair genes in 15/49 (30.6%) evaluable pts. While a majority of these genomic aberrations occurred in BRCA2 and ATM, biallelic loss of other relevant genes, including members of the Fanconi Anemia complementation group and CHEK2, were also observed. Among these fifteen pts, 13 (86.7%) responded to olaparib. All seven pts with BRCA2 loss (somatic [4/7] or germline [3/7]) and 4/5 pts with ATM truncating mutations responded to olaparib. The specificity of the biomarker suite was 94% in this population. Conversely, PTEN loss and ERG rearrangements were not associated with response. Finally, consistent with previous studies of olaparib, anemia (10/50, 20%) and fatigue (6/50, 12%) were the most common grade>3 adverse events, with 13 (26%) pts requiring a dose reduction. Conclusions: Olaparib has durable antitumor activity in heavily pre-treated pts with sporadic mCRPC with a 32.7% overall response rate. Genomic defects in DNA repair genes associate with olaparib sensitivity in sporadic mCRPC, offering a possibility for the very first molecular treatment stratification of advanced prostate cancer. Citation Format: Joaquin Mateo, Shahneen Sandhu, Susana Miranda, Suzanne Carreira, Suneil Jain, Christy Ralph, Andrew Protheroe, Syed Hussain, Robert Jones, Tony Elliot, Ursula McGovern, Alexa Gillman, Claire Paulding, Helen Mossop, Nuria Porta, Diletta Bianchini, Zafeiris Zafeiriou, Gunther Boysen, Daniel Nava Rodrigues, Penelope Flohr, George Seed, Jane Goodall, Ines Figueiredo, Raquel Perez-Lopez, Nina Tunariu, Aurelius Omlin, Roberta Ferraldeschi, Lakshmi P. Kunju, Rosalind Eeles, Gerhardt Attard, Dan Robinson, Arul Chinnaiyan, Emma Hall, Johann S. de Bono. DNA repair defects and antitumor activity with PARP inhibition: TOPARP, a phase II trial of olaparib in metastatic castration resistant prostate cancer. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr CT322. doi:10.1158/1538-7445.AM2015-CT322

5051 Background: An urgent need exists for new therapies after progression (PD) onabiraterone (AA) and enzalutamide (ENZ). PR expression increases with castration resistance [Bonkhoff 2001]. ONA, a...

TPS5097 Background: PR expression in prostate cancer increases with resistance to castration [Bonkhoff 2001]. The transcriptional, activated PR (APR), offers a potential target in advanced CRPC. ON...

180 Background: Advanced prostate cancer (APC) is a molecularly heterogeneous disease, with evidence of clonal evolution that could be responsible for resistance to treatment. About 90% of patients (pts) with APC have bone metastases. The acquisition of a bone marrow biopsies (BMBs) is a safe and feasible technique for obtaining tissue, with a low rate of complications. We hypothesized that pre-biopsy clinical variables may increase the success rate of BMBs in APC. Methods: Standard BMBs of the iliac crest were performed in APC pts between October 2011 and June 2013. All pts signed ethics approved consent. In the control cohort (n=10) BMBs were collected in pts with normal CT and bone scan appearance. Minimum, maximum, and mean Hounsfield Units (HU) of the iliac crest on pre-biopsy CTs were determined. Clinical and laboratory variables were collected from the electronic record system. Biopsies were defined as containing 50 or more or 1 to 50 malignant cells or none (negative). Univariate analysis was performed to determine variables associated with biopsy positivity with 50 or more cells. For variables with p value

215 Background: Falls in prostate specific antigen (PSA) levels by 50% from the baseline at 12 weeks are currently used to assess response to treatment for mCRPC (Scher et al, 2008). However PSA decline algorithms do not provide robust intermediate endpoints of overall survival (OS) benefit in mCRPC. We evaluated the association between PSA decline at 4 weeks and OS. Methods: We identified mCRPC patients who had received treatment with abiraterone acetate (AA) plus prednisolone post-docetaxel at the Royal Marsden (London, UK) between 01.01.2006 and 30.04.14. Patients were eligible for this analysis if they had PSA levels assessed at baseline, after 4 weeks and 12 weeks of treatment. PSA response at 4 weeks was defined as a ≥30% (PSA4w30) and ≥50% (PSA4w50) decline from baseline (PSABL). Association with outcome was analyzed using multivariate Cox regression and log-rank analyses. A significant p-value of 0.0167 was pre-specified to account for multiple testing. Demographics and clinical data were retrospectively collected from the hospital electronic patient record system (EPR). Results: We identified 124 patients who had received AA post-docetaxel and were eligible for this analysis. PSA4w30 was associated with longer OS (median OS 11.1 vs. 6.8 months; HR 0.50; 95% CI 0.32-0.80; p=.004). PSA4w50 was not associated with OS. A ≥50% PSA decline at 12 weeks (PSA12w50), the standard response measure, was also associated with OS (median OS 9.3 vs. 8.2; HR 0.49; 95% CI 0.29-0.80; p=.005). PSA4w30 was significantly associated with PSA12w50 (p

278 Background: PSA decline (PSAD) in CRPC after withdrawal of antiandrogens and steroid related drugs is well established. DW responses have been anecdotal and not well characterized. In this study we investigated the frequency and magnitude of PSA changes after DW. Methods: We retrospectively identified patients treated in the Royal Marsden for CRPC with D monotherapy. Patients were considered evaluable if they had between DW and their next treatment or radiotherapy an interval of at least 7 days, no other intervention and at least one PSA reading. Patients who received radiotherapy during treatment with D or received D for palliation of symptoms were excluded. The number of patients showing PSAD was recorded together with its percentage change from baseline. Chi-square test was used to compare response rates between different groups and 95% confidence intervals (CI) for the description of frequencies. PSA progression (PSAP) was defined according to Prostate Cancer Working Group 2 criteria. Results: 200 patients were identified who had received D of which 50 were evaluable. During D treatment PSA responses were not available for 5 patients, while 16 (35%, 95%CI [20%-50%]) had a ≥ 50% PSAD which was confirmed a month later with a second reading. For the responders, the median duration of PSA response from initiation of treatment to PSAP was 293 days (range: 219 to 1063). After DW, PSAD was observed in 12 patients (24%, 95% CI [12%,36%]). PSAD ≥ 25%, ≥ 30% and ≥ 50% was observed in 6, 3 and 2 patients respectively (12%, 6% and 4%) and in only one could the ≥ 30% PSAD be confirmed with a second reading a month later. In 5 cases of ≥ 25% PSAD, next treatment was initiated despite a dropping PSA, after 8 to 43 days. In one case only was PSAP reached during DW with a response duration of 53 days from DW to PSAP. The frequency of ≥ 25% PSAW responses was not significantly different between patients with and without prior response to dexamethasone: 6% and 17% respectively, Chi-square test p = 0.29. One patient reported improvement of his urinary symptoms after DW. Conclusions: DW responses are observed in a minority of patients. This phenomenon merits further prospective characterization and needs to be considered in the design of clinical trials.