Colorectal cancer risk stratification on histological slides based on survival curves predicted by deep learning

Studies have shown that colorectal cancer prognosis can be predicted by deep learning-based analysis of histological tissue sections of the primary tumor. So far, this has been achieved using a binary prediction. Survival curves might contain more detailed information and thus enable a more fine-grained risk prediction. Therefore, we established survival curve-based CRC survival predictors and benchmarked them against standard binary survival predictors, comparing their performance extensively on the clinical high and low risk subsets of one internal and three external cohorts. Survival curve-based risk prediction achieved a very similar risk stratification to binary risk prediction for this task. Exchanging other components of the pipeline, namely input tissue and feature extractor, had largely identical effects on model performance independently of the type of risk prediction. An ensemble of all survival curve-based models exhibited a more robust performance, as did a similar ensemble based on binary risk prediction. Patients could be further stratified within clinical risk groups. However, performance still varied across cohorts, indicating limited generalization of all investigated image analysis pipelines, whereas models using clinical data performed robustly on all cohorts.

Transgenic HPV11-E2 protein modulates URR activity in vivo

In vitro experiments have shown that the E2 protein of human papillomaviruses (HPV) binds to the upstream regulatory region (URR) of the viral genome and modulates transcription. Additionally, it seems to be a necessary component for viral DNA replication together with E1. We have developed a transgenic mouse model containing the URR region of the low-risk virus HPV11 that regulates the expression of the lacZ reporter gene. Most interestingly, in these mice, the transgene was exclusively expressed in the bulge region of the hair follicle but not in any other tissues. Further experimental data indicate that in double transgenic mice that also express the HPV11-E2 protein under the control of the Ubiquitin C-promoter, the transcription of the reporter gene is modulated. When E2 is present, the expression of the reporter gene also occurs exclusively in the bulge region of the hair follicles as it does in the single transgenic mice, but the expression of the lacZ driven by the URR is increased and the statistical spread is greater. Even if the expression of the reporter gene occurs in the hair follicles of the dorsal skin of an animal uniform, E2 obviously has the capacity for both to induce and to repress the URR activity in vivo.

Drug sensitivity profiling of 3D tumor tissue cultures in the pediatric precision oncology program INFORM

The international precision oncology program INFORM enrolls relapsed/refractory pediatric cancer patients for comprehensive molecular analysis. We report a two-year pilot study implementing ex vivo drug sensitivity profiling (DSP) using a library of 75-78 clinically relevant drugs. We included 132 viable tumor samples from 35 pediatric oncology centers in seven countries. DSP was conducted on multicellular fresh tumor tissue spheroid cultures in 384-well plates with an overall mean processing time of three weeks. In 89 cases (67%), sufficient viable tissue was received; 69 (78%) passed internal quality controls. The DSP results matched the identified molecular targets, including BRAF, ALK, MET, and TP53 status. Drug vulnerabilities were identified in 80% of cases lacking actionable (very) high-evidence molecular events, adding value to the molecular data. Striking parallels between clinical courses and the DSP results were observed in selected patients. Overall, DSP in clinical real-time is feasible in international multicenter precision oncology programs.

MODL-15. High-throughput combination drug screening identifies synergism between retinoic acid treatment and BCL-XL-inhibition in MYC(N)-driven medulloblastoma and neuroblastoma models

PURPOSE: Despite remarkable improvements in childhood cancer survival, certain high-risk entities including malignancies of the nervous system still carry dismal prognoses. Retinoic acid (RA) treatment has long been administered in high-risk neuroblastoma patients and preclinical data suggest a benefit in applying retinoids in selected brain tumor entities. However, limited single-agent efficacy and developing treatment resistance provide a rationale for investigating improved combination treatments. METHODS: We assessed the RA sensitivity of 16 cell lines and patient-derived cultures of pediatric nervous system tumors from the INFORM (INdividualized Therapy FOr Relapsed Malignancies in Childhood) registry. Bulk RNA sequencing was performed for five sensitive models undergoing RA treatment. All models were screened for drug sensitivity to 76 clinically relevant drugs alone and combined with RA. Beneficial hit combinations were further investigated for synergy, as well as their effect on differentiation and apoptosis by high-content fluorescence microscopy and caspase activity assay. Results from in vivo experiments are pending. RESULTS: Group 3 medulloblastoma and high-risk neuroblastoma models were most sensitive to RA treatment leading to significant changes in gene expression of apoptotic regulation. Drug sensitivity screening revealed similar patterns of response to combination treatments in MYC-driven Group 3 medulloblastomas and MYCN-amplified neuroblastomas. Apoptosis regulating BCL-XL-inhibitors (A-1155463, navitoclax) were identified as top hits across RA sensitive models, whereas epigenetic BET family inhibitor I-BET151 and histone deacetylase inhibitor entinostat suggested entity-specific combination benefits in neuroblastoma and medulloblastoma models, respectively. In both entities, combining RA with navitoclax was synergistic and significantly increased caspase-3 activity. The combination led to a morphological shift from differentiation under RA treatment to cell death. CONCLUSION: Exploring combinations for RA treatment in pediatric nervous system tumors, we found that MYC(N)-driven medulloblastoma and neuroblastoma not only share responsiveness to RA treatment, but also demonstrate enhanced vulnerability in combination with BCL-XL-inhibition resulting in increased apoptosis.

DDEL-01. The role of key pharmacodynamic and pharmacokinetic parameters in drug response prediction of pediatric tumors in the precision oncology study INFORM

INTRODUCTION: The INFORM (INdividualized Therapy FOr Relapsed Malignancies in Childhood) study is a European pediatric precision oncology program. Using state of the art molecular assays, INFORM aims for identification of targetable genetic alterations, matching drugs and clinical trials. High evidence targets were associated with doubling of progression free survival when patients received a matching drug. However, the fraction of tumors with high evidence drug targets remains low requiring functional layers of information such as drug sensitivity profiling. The aim of this project is to identify and investigate the role of key pharmacodynamic and pharmacokinetic parameters to improve the predictivity of ex vivo drug response of pediatric tumors. METHODS: Positive control cell lines harboring specific mutations (n=7) and primary tumors (n=121) from INFORM, including 10% ependymomas, 7% high grade gliomas, 5% neuroblastomas and 4% medulloblastomas, were profiled ex vivo using a library of n=76 clinically relevant oncology drugs in a 384 well plate format. Metabolic activity was measured after 72h of treatment. Quality control (QC) was done using the robust z-factor, correlation of replicates and mean negative control. Hit selection was based on maximum percentage inhibition, normalized AUC metric (DSSasym) and maximum serum concentration (Cmax) of the drug. Clinical follow-up was collected using a questionnaire. RESULTS: A linear mixed model revealed the DSSasym to be the strongest pharmacodynamic parameter in drug prediction in cell lines. Drug screens of n=105 INFORM cases passed QC. Application of the filtering parameters resulted in prediction of n=1-16 drugs/case (min-max). A data base of published pediatric pharmacokinetic parameters of the drug library was generated. Analysis of predictive parameters and clinical follow-up of clinical samples is ongoing. CONCLUSION: Including pharmacodynamic as well as clinical pharmacokinetic parameters is paramount to identify potentially clinically active compounds from ex vivo drug screen data. Further algorithm development is warranted.

Predictive modeling of resistance to SMO-inhibition in a patient-derived orthotopic xenograft model of SHH medulloblastoma

Background

Inhibition of the sonic hedgehog (SHH) pathway with Smoothened (SMO) inhibitors is a promising treatment strategy in SHH-activated medulloblastoma, especially in adult patients. However, the problem is that tumors frequently acquire resistance to the treatment. To understand the underlying resistance mechanisms and to find ways to overcome the resistance, preclinical models that became resistant to SMO inhibition are needed.

Methods

To induce SMO inhibitor resistant tumors, we have treated a patient-derived xenograft (PDX) model of SHH medulloblastoma, sensitive to SMO inhibition, with 20 mg/kg Sonidegib using an intermitted treatment schedule. Vehicle-treated and resistant models were subjected to whole-genome and RNA sequencing for molecular characterization and target engagement. In vitro drug screens (76 drugs) were performed using Sonidegib-sensitive and -resistant lines to find other drugs to target the resistant lines. One of the top hits was then validated in vivo.

Results

Nine independent Sonidegib-resistant PDX lines were generated. Molecular characterization of the resistant models showed that eight models developed missense mutations in SMO and one gained an inactivating point mutation in MEGF8, which acts downstream of SMO as a repressor in the SHH pathway. The in vitro drug screen with Sonidegib-sensitive and -resistant lines identified good efficacy for Selinexor in the resistant line. Indeed, in vivo treatment with Selinexor revealed that it is more effective in resistant than in sensitive models.

Conclusions

We report the first human SMO inhibitor resistant medulloblastoma PDX models, which can be used for further preclinical experiments to develop the best strategies to overcome the resistance to SMO inhibitors in patients.

Biosensor for deconvolution of individual cell fate in response to ion beam irradiation

Clonogenic survival assay constitutes the gold standard method for quantifying radiobiological effects. However, it neglects cellular radiation response variability and heterogeneous energy deposition by ion beams on the microscopic scale. We introduce "Cell-Fit-HD4D" a biosensor that enables a deconvolution of individual cell fate in response to the microscopic energy deposition as visualized by optical microscopy. Cell-Fit-HD4D enables single-cell dosimetry in clinically relevant complex radiation fields by correlating microscopic beam parameters with biological endpoints. Decrypting the ion beam's energy deposition and molecular effects at the single-cell level has the potential to improve our understanding of radiobiological dose concepts as well as radiobiological study approaches in general.

Deep learning can predict lymph node status directly from histology in colorectal cancer

BACKGROUND

Lymph node status is a prognostic marker and strongly influences therapeutic decisions in colorectal cancer (CRC).

OBJECTIVES

The objective of the study is to investigate whether image features extracted by a deep learning model from routine histological slides and/or clinical data can be used to predict CRC lymph node metastasis (LNM).

METHODS

Using histological whole slide images (WSIs) of primary tumours of 2431 patients in the DACHS cohort, we trained a convolutional neural network to predict LNM. In parallel, we used clinical data derived from the same cases in logistic regression analyses. Subsequently, the slide-based artificial intelligence predictor (SBAIP) score was included in the regression. WSIs and data from 582 patients of the TCGA cohort were used as the external test set.

RESULTS

On the internal test set, the SBAIP achieved an area under receiver operating characteristic (AUROC) of 71.0%, the clinical classifier achieved an AUROC of 67.0% and a combination of the two classifiers yielded an improvement to 74.1%. Whereas the clinical classifier's performance remained stable on the TCGA set, performance of the SBAIP dropped to an AUROC of 61.2%. Performance of the clinical classifier depended strongly on the T stage.

CONCLUSION

Deep learning-based image analysis may help predict LNM of patients with CRC using routine histological slides. Combination with clinical data such as T stage might be useful. Strategies to increase performance of the SBAIP on external images should be investigated.

Efficacy and Safety of Checkpoint Inhibitor Treatment in Patients with Advanced Renal or Urothelial Cell Carcinoma and Concomitant Chronic Kidney Disease: A Retrospective Cohort Study

Simple Summary

Immune checkpoint inhibition plays a pivotal role in the treatment of metastatic renal cell carcinoma and metastatic urothelial carcinoma. The association of chronic kidney disease with these tumors is well established. However, to what extent kidney failure modifies the efficacy or the toxicity profiles of checkpoint inhibitors has been poorly investigated. In this paper, we reviewed the files of 85 patients with renal cell carcinoma and 41 with urothelial cancer who had received checkpoint inhibitor treatment, and found that 37.6% and 41.5% had evidence of chronic kidney disease, respectively. We found that neither general treatment-related nor immune-related adverse events differed between patients with normal or impaired renal function. Using a multivariate analysis, we found that chronic kidney disease had no effect on progression-free survival. However, irrespective of the tumor entity, chronic kidney disease was found to positively influence overall survival. We conclude that treatment with checkpoint inhibitors in patients with chronic kidney disease is safe and efficient.

Abstract

Background: Checkpoint inhibitors are a standard of care in the treatment of advanced renal cell carcinoma (RCC) and urothelial carcinoma (UC). Patients with these tumors often suffer from concomitant chronic kidney disease (CKD). Limited data are available on the efficacy and toxicity of checkpoint inhibitors in patients with CKD. Methods: We retrospectively analyzed 126 patients who received checkpoint inhibitors for RCC (n = 85) or UC (n = 41) and analyzed the frequency of treatment- and immune-related adverse events (AEs). We performed a multivariate analysis to determine progression-free survival (PFS) and overall survival (OS). Results: A total of 38.9% of patients had CKD. Frequencies of general AEs (49.0% in CKD vs. 48.1%, p > 0.99999) and immune-related AEs (28.6 vs. 24.7%, p ≥ 0.9999) did not significantly differ between the groups. There was no difference in PFS for patients with RCC or UC and CKD or without CKD (RCC: 6.81 vs. 7.54 months, HR 1.000 (95%CI 0.548–01.822), p = 0.999; UC:2.33 vs. 3.67 months, HR 01.492 (95%CI 0.686–3.247), p = 0.431). CKD appeared to be a potential effect modifier for OS in both RCC and UC (RCC: NR vs. 23.9 months, HR 0.502 (95%CI 0.219–1.152), p = 0.104; UC:18.84 vs. 15.42 months, HR 0.656 (95%CI 0.296–1.454), p = 0.299). Conclusions: Checkpoint inhibitor treatment in our cohort of patients with CKD was as safe and efficient as in the cohort of patients without CKD.

Predicting the Risk of Metastases by PSMA-PET/CT-Evaluation of 335 Men with Treatment-Naïve Prostate Carcinoma

Simple Summary

Prostate carcinoma is the most common visceral cancer for men and the second most common cause of death. The early detection of micrometastasis may improve clinical outcome due to individual treatment approaches like early intensified therapy. Imaging using prostate-specific membrane antigen-positron emission tomography/computed tomography (PSMA-PET/CT) has a high potential of detecting even small metastases. Therefore, the present study aimed to analyze data of 335 men with primary diagnosed prostate cancer and available PSMA-PET/CT with regard to characteristic PET-parameters and the detection of metastases. We observed that an increased accumulation of the PET-tracer measured in the primary tumor significantly correlates with the presence of distant metastases. The current results may be helpful in decision making of individual treatment escalation for a variety of men with aggressive disease which should improve clinical outcome.

Abstract

Men diagnosed with aggressive prostate cancer are at high risk of local relapse or systemic progression after definitive treatment. Treatment intensification is highly needed for that patient cohort; however, no relevant stratification tool has been implemented into the clinical work routine so far. Therefore, the aim of the current study was to analyze the role of initial PSMA-PET/CT as a prediction tool for metastases. In total, 335 men with biopsy-proven prostate carcinoma and PSMA-PET/CT for primary staging were enrolled in the present, retrospective study. The number and site of metastases were analyzed and correlated with the maximum standardized uptake value (SUVmax) of the intraprostatic, malignant lesion. Receiver operating characteristic (ROC) curves were used to determine sensitivity and specificity and a model was created using multiple logistic regression. PSMA-PET/CT detected 171 metastases with PSMA-uptake in 82 patients. A statistically significant higher SUVmax was found for men with metastatic disease than for the cohort without distant metastases (median 16.1 vs. 11.2; p < 0.001). The area under the curve (AUC) in regard to predicting the presence of any metastases was 0.65. Choosing a cut-off value of 11.9 for SUVmax, a sensitivity and specificity (factor 1:1) of 76.0% and 58.4% was obtained. The current study confirms, that initial PSMA-PET/CT is able to detect a relatively high number of treatment-naïve men with metastatic prostate carcinoma. Intraprostatic SUVmax seems to be a promising parameter for the prediction of distant disease and could be used for treatment stratification—aspects which should be verified within prospective trials.

Performance of [68Ga]Ga-PSMA-11 PET/CT in patients with recurrent prostate cancer after prostatectomy-a multi-centre evaluation of 2533 patients

PURPOSE

To evaluate the performance of [⁶⁸Ga]Ga-PSMA-11 PET/CT in the diagnosis of recurrent prostate cancer (PC) after prostatectomy in a large multicentre cohort.

METHODS

The centres, which contributed to this study, were the departments of nuclear medicine of Heidelberg (Germany), Technical University of Munich (Germany) and Albert Einstein Hospital of São Paulo (Brazil). A total of 2533 patients who were scanned with [⁶⁸Ga]Ga-PSMA-11 PET/CT at 1 h p.i. due to recurrent PC after prostatectomy were included in this retrospective analysis. Exclusion criteria were as follows: patients with untreated primary tumour, previous chemotherapy or Xofigo®; those previously treated with exclusively external beam radiation therapy or HIFU; those referred for PSMA-therapy; and those treated with ADT (including first- and second-generation ADT) within the last 6 months. Potential influences of different factors such as PSA level, PSA doubling-time (PSA_DT), PSA velocity (PSA_Vel), Gleason Score (GSC, including the separate analysis of 7a and 7b), age and amount of injected tracer were evaluated in a multivariable analysis.

RESULTS

The rate of pathologic PET/CT-scans was 43% for PSA ≤ 0.2 ng/ml, 58% for PSA > 0.2 to ≤ 0.5, 72% for PSA > 0.5 to ≤ 1.0 and increased to a maximum of 93% for PSA > 10 ng/ml. A pathological PET/CT was significantly (p = 0.001) associated with PSA level and higher GSC. Amount of injected tracer, age, PSA_DT and PSA_Vel were not associated with a higher probability of a pathological scan.

CONCLUSION

[⁶⁸Ga]Ga-PSMA-11 PET/CT at 1 h p.i. confirmed its high performance in the largest patient cohort yet analysed. Tumour detection showed a clear association with higher PSA and higher GSC. No association was found between a pathological [⁶⁸Ga]Ga-PSMA-11 PET/CT and age, amount of injected tracer, PSA_DT or PSA_Vel.

Potential therapeutic effect of low-dose paclitaxel in melanoma patients resistant to immune checkpoint blockade: A pilot study

The low dose application of chemotherapeutic agents such as paclitaxel was previously shown to initiate anti-tumor activity by neutralizing myeloid-derived suppressor cells (MDSCs) in melanoma mouse models. Here, we investigated immunomodulating effects of low-dose paclitaxel in 9 metastatic melanoma patients resistant to prior treatments. Three patients showed response to therapy (two partial responses and one stable disease). In responding patients, paclitaxel decreased the frequency and immunosuppressive pattern of MDSCs in the peripheral blood and skin metastases. Furthermore, paclitaxel modulated levels of inflammatory mediators in the serum. In addition, responders displayed enhanced frequencies of tumor-infiltrating CD8⁺ T cells and their activity indicated by the upregulation of CD25 and TCR ζ-chain expression. Our study suggests that low-dose paclitaxel treatment could improve clinical outcome of some advanced melanoma patients by enhancing anti-tumor immunity and might be proposed for combined melanoma immunotherapy.

The design heatmap: A simple visualization of D -optimality design problems

Optimal experimental designs are often formal and specific, and not intuitively plausible to practical experimenters. However, even in theory, there often are many different possible design points providing identical or nearly identical information compared to the design points of a strictly optimal design. In practical applications, this can be used to find designs that are a compromise between mathematical optimality and practical requirements, including preferences of experimenters. For this purpose, we propose a derivative-based two-dimensional graphical representation of the design space that, given any optimal design is already known, will show which areas of the design space are relevant for good designs and how these areas relate to each other. While existing equivalence theorems already allow such an illustration in regard to the relevance of design points only, our approach also shows whether different design points contribute the same kind of information, and thus allows tweaking of designs for practical applications, especially in regard to the splitting and combining of design points. We demonstrate the approach on a toxicological trial where a D -optimal design for a dose-response experiment modeled by a four-parameter log-logistic function was requested. As these designs require a prior estimate of the relevant parameters, which is difficult to obtain in a practical situation, we also discuss an adaption of our representations to the criterion of Bayesian D -optimality. While we focus on D -optimality, the approach is in principle applicable to different optimality criteria as well. However, much of the computational and graphical simplicity will be lost.

Drawing statistical conclusions from experiments with multiple quantitative measurements per subject

In experiments with multiple quantitative measurements per subject, for example measurements on multiple lesions per patient, the additional measurements on the same patient provide limited additional information. Treating these measurements as independent observations will produce biased estimators for standard deviations and confidence intervals, and increases the risk of false positives in statistical tests. The problem can be remedied in a simple way by first taking the average of all observations of each specific patient, and then doing all further calculations only on the list of these patient means. A more sophisticated statistical modeling of the experiment, for example in a linear mixed model, is only required if (i) there is a large imbalance in the number of observations per patient or (ii) there is a specific interest in actually identifying the various sources of variation in the experiment.

Diagnostic Accuracy of 18F-PSMA-1007 PET/CT Imaging for Lymph Node Staging of Prostate Carcinoma in Primary and Biochemical Recurrence

Prostate-specific membrane antigen (PSMA)-ligand PET/CT is performed on patients with prostate cancer to stage the disease initially or to identify sites of recurrence after definitive therapy. On the basis of clinical results, ¹⁸F-PSMA-1007 is a promising PSMA PET tracer, but detailed histologic confirmation has been lacking. Methods: Ninety-six patients with prostate cancer underwent ¹⁸F-PSMA-1007 PET/CT followed by either radical prostatectomy with lymphadenectomy or salvage lymphadenectomy. The histologic findings of PSMA PET-positive nodes were analyzed retrospectively. A lesion-based and patient-based analysis was performed comparing all positive lesions and only lesions larger than 3 mm on histopathology. Results: Of the patients, 90.6% received ¹⁸F-PSMA-1007 PET/CT for staging before the primary treatment, whereas 9.4% underwent imaging for biochemical recurrence. In 34.4% of the cohort, positive lymph nodes were present on imaging. In total, 1,746 lymph nodes were dissected in 96 patients. ¹⁸F-PSMA-1007 PET had a lesion-based sensitivity of 81.7%, a specificity of 99.6%, a positive predictive value of 92.4%, and a negative predictive value of 98.9% for detecting positive lymph nodes larger than 3 mm. In the analysis of all malignant nodes regardless of size, the overall sensitivity, specificity, positive predictive value, and negative predictive value on lesion-based analysis were 71.2%, 99.5%, 91.3%, and 97.9%, respectively. The patient-based analysis showed a sensitivity of 85.9% and a specificity of 99.5% for lymph nodes larger than 3 mm. Conclusion: ¹⁸F-PSMA-1007 PET/CT reliably detects malignant lymph nodes and has an exceptional specificity of more than 99% for nodal metastases.

Artificial Intelligence in Skin Cancer Diagnostics: The Patients' Perspective

Background: Artificial intelligence (AI) has shown promise in numerous experimental studies, particularly in skin cancer diagnostics. Translation of these findings into the clinic is the logical next step. This translation can only be successful if patients' concerns and questions are addressed suitably. We therefore conducted a survey to evaluate the patients' view of artificial intelligence in melanoma diagnostics in Germany, with a particular focus on patients with a history of melanoma.

Participants and Methods: A web-based questionnaire was designed using LimeSurvey, sent by e-mail to university hospitals and melanoma support groups and advertised on social media. The anonymous questionnaire evaluated patients' expectations and concerns toward artificial intelligence in general as well as their attitudes toward different application scenarios. Descriptive analysis was performed with expression of categorical variables as percentages and 95% confidence intervals. Statistical tests were performed to investigate associations between sociodemographic data and selected items of the questionnaire.

Results: 298 individuals (154 with a melanoma diagnosis, 143 without) responded to the questionnaire. About 94% [95% CI = 0.91–0.97] of respondents supported the use of artificial intelligence in medical approaches. 88% [95% CI = 0.85–0.92] would even make their own health data anonymously available for the further development of AI-based applications in medicine. Only 41% [95% CI = 0.35–0.46] of respondents were amenable to the use of artificial intelligence as stand-alone system, 94% [95% CI = 0.92–0.97] to its use as assistance system for physicians. In sub-group analyses, only minor differences were detectable. Respondents with a previous history of melanoma were more amenable to the use of AI applications for early detection even at home. They would prefer an application scenario where physician and AI classify the lesions independently. With respect to AI-based applications in medicine, patients were concerned about insufficient data protection, impersonality and susceptibility to errors, but expected faster, more precise and unbiased diagnostics, less diagnostic errors and support for physicians.

Conclusions: The vast majority of participants exhibited a positive attitude toward the use of artificial intelligence in melanoma diagnostics, especially as an assistance system.

Multiplex quantitation of 270 plasma protein markers to identify a signature for early detection of colorectal cancer

Blood-based protein biomarker signatures might be an alternative or supplement to existing methods for early detection of colorectal cancer (CRC) for population-based screening. The objective of this study was to derive a protein biomarker signature for early detection of CRC and its precursor advanced adenoma (AA). In a two-stage design, 270 protein markers were measured by liquid chromatography/multiple reaction monitoring/mass spectrometry in plasma samples of discovery and validation sets. In the discovery set consisting of 100 newly diagnosed CRC cases and 100 age- and sex-matched controls free of neoplasm at screening colonoscopy, the algorithms predicting the presence of early- or late-stage CRC were derived by Lasso regression and .632 + bootstrap. The prediction algorithms were then externally validated in an independent validation set consisting of participants of screening colonoscopy including 56 participants with CRC, 99 with AA and 99 controls without any colorectal neoplasms. Three different signatures for all-, early- and late-stage CRC consisting of five-, three- and eight-protein markers were obtained in the discovery set with areas under the curves (AUCs) after .632 + bootstrap adjustment of 0.85, 0.83 and 0.96, respectively. External validation in the representative screening population yielded AUCs of 0.79 (95% CI, 0.70-0.86), 0.79 (95% CI, 0.66-0.89) and 0.80 (95% CI, 0.70-0.89) for all-, early- and late-stage CRCs, respectively. The three-marker early-stage algorithm yielded an AUC of 0.65 (95% CI, 0.56-0.73) for detection of AA in the validation set. Although not yet competitive with available stool-based tests for CRC early detection, the identified proteins may contribute to the development of powerful blood-based tests for early detection of CRC and its precursors AAs.

Tumor microenvironment-derived S100A8/A9 is a novel prognostic biomarker for advanced melanoma patients and during immunotherapy with anti-PD-1 antibodies

BACKGROUND

Predicting metastasis in melanoma patients is important for disease management and could help to identify those who might benefit from adjuvant treatment. The aim of this study was to investigate whether the tumor microenvironment-derived protein S100A8/A9 qualifies as prognostic marker for melanoma patients, also in the setting of immunotherapy.

METHODS

S100A8/A9 gene and protein expression were analyzed on melanocytic nevi, primary melanomas and metastases using a cDNA library and three independent tissue-microarrays (TMA). Serum levels of S100A8/A9 were measured using a specific ELISA in two independent cohorts of 354 stage III and stage IV melanoma patients as well as in two independent cohorts of patients treated with the PD-1 antibody pembrolizumab.

RESULTS

cDNA analysis revealed an upregulation of S100A8 and S100A9 gene expression in melanoma metastases compared to primary melanomas. Significantly higher numbers of infiltrating S100A8/A9 positive cells were found in tissue samples of metastasizing primary melanomas compared to non-metastasizing melanomas (P < .0001) and in melanomas of short-term survivors compared to long-term survivors (P < .0001). Serum S100A8/A9 levels > 5.5 mg/l were associated with impaired overall survival in two independent cohorts (both P < .0001). Importantly, patients with serum elevated S100A8/A9 treated with pembrolizumab showed significantly impaired survival compared to patients with lower S100A8/A9 levels (cohort 1: P = .0051; cohort 2: P < .0001).

CONCLUSIONS

The tumor microenvironment-associated protein S100A8/A9 serves as a novel prognostic marker for metastasis and survival of metastatic melanoma patients and predicts response to immunotherapy with pembrolizumab. These data underscore the significance of tumor microenvironment-derived factors as suitable biomarkers for melanoma.

68Ga-PSMA-11 PET/CT in patients with recurrent prostate cancer-a modified protocol compared with the common protocol

PURPOSE

⁶⁸Ga-PSMA-11 PET/CT is commonly performed at 1 h post injection (p.i.). However, various publications have demonstrated that most prostate cancer (PC) lesions exhibit higher contrast at later imaging. The aim of this study was to compare the "common" protocol of ⁶⁸Ga-PSMA-11 PET/CT with a modified protocol.

METHODS

In 2017, we used the following scanning protocol for ⁶⁸Ga-PSMA-11 PET/CT in patients with recurrent PC: acquisition at 1 h p.i. without further preparations. From 2018, all scans were conducted at 1.5 h p.i. In addition, patients were orally hydrated with 1 L of water 0.5 h p.i. and were injected with 20 mg of furosemide 1 h p.i. Both protocols including 112 patients (2017) and 156 (modified protocol in 2018) were retrospectively compared. Rates of pathologic scans, maximum standardized uptake values (SUVmax), and tumor contrast (ratio lesion-SUVmax/background-SUVmean) as well as average standardized uptake values (SUVmean) of urinary bladder were analyzed.

RESULTS

Both tumor contrast and tracer uptake were significantly (p < 0.001) higher in the novel protocol. Although statistically not significant, the rates of pathologic scans were also higher in the modified protocol: 76.3% vs. 68.8% for all PSA values including 38.9% vs. 25.0% for PSA < 0.5 ng/ml and 60.0% vs. 56.7% for PSA > 0.5-≤ 2.0 ng/ml. Average SUVmean of the urinary bladder was significantly (p < 0.001) lower with the modified protocol.

CONCLUSIONS

The modified protocol, which includes a combination of delayed image acquisition at 1.5 h p.i., hydration, and furosemide resulted in higher tumor contrast and seems to have the potential to increase the rates of pathological scans, especially at low PSA levels.

Response Prediction of 177Lu-PSMA-617 Radioligand Therapy Using Prostate-Specific Antigen, Chromogranin A, and Lactate Dehydrogenase

Neuroendocrinelike transdifferentiation of prostate cancer adenocarcinomas correlates with serum levels of chromogranin A (CgA) and drives treatment resistance. The aim of this work was to evaluate whether CgA can serve as a response predictor for ¹⁷⁷Lu-prostate-specific membrane antigen 617 (PSMA) radioligand therapy (RLT) in comparison with the established tumor markers. Methods: One hundred consecutive patients with metastasized castration-resistant prostate cancer scheduled for PSMA RLT were evaluated for prostate-specific antigen (PSA), lactate dehydrogenase (LDH), and CgA at baseline and in follow-up of PSMA RLT. Tumor uptake of PSMA ligand, a known predictive marker for response, was assessed as a control variable. Results: From the 100 evaluated patients, 35 had partial remission, 16 stable disease, 15 mixed response, and 36 progression of disease. Tumor uptake above salivary gland uptake translated into partial remission, with an odds ratio (OR) of 60.265 (95% confidence interval [CI], 5.038-720.922). Elevated LDH implied a reduced chance for partial remission, with an OR of 0.094 (95% CI, 0.017-0.518), but increased the frequency of progressive disease (OR, 2.717; 95% CI, 1.391-5.304). All patients who achieved partial remission had a normal baseline LDH. Factor-2 elevation of CgA increased the risk for progression, with an OR of 3.089 (95% CI, 1.302-7.332). Baseline PSA had no prognostic value for response prediction. Conclusion: In our cohort, baseline PSA had no prognostic value for response prediction. LDH was the marker with the strongest prognostic value, and elevated LDH increased the risk for progression of disease under PSMA RLT. Elevated CgA demonstrated a moderate impact as a negative prognostic marker in general but was explicitly related to the presence of liver metastases. Well in line with the literature, sufficient tumor uptake is a prerequisite to achieve tumor response.

Mapping Active Gene-Regulatory Regions in Human Repopulating Long-Term HSCs

Genes that regulate hematopoietic stem cell (HSC) self-renewal, proliferation, and differentiation are tightly controlled by regulatory regions. However, mapping such regions relies on surface markers and immunophenotypic definition of HSCs. Here, we use γ-retroviral integration sites (γRV ISs) from a gene therapy trial for 10 patients with Wiskott-Aldrich syndrome to mark active enhancers and promoters in functionally defined long-term repopulating HSCs. Integration site clusters showed the highest ATAC-seq signals at HSC-specific peaks and strongly correlated with hematopoietic risk variants. Tagged genes were significantly enriched for HSC gene sets. We were able to map over 3,000 HSC regulatory regions in late-contributing HSCs, and we used these data to identify miR-10a and miR-335 as two miRNAs regulating early hematopoiesis. In this study, we show that viral insertion sites can be used as molecular tags to assess chromatin conformation on functionally defined cell populations, thereby providing a genome-wide resource for regulatory regions in human repopulating long-term HSCs.

Lymph Node Involvement in Treatment-Naïve Prostate Cancer Patients: Correlation of PSMA PET/CT Imaging and Roach Formula in 280 Men in Radiotherapeutic Management

The importance of prostate-specific membrane antigen (PSMA) PET/CT for primary staging of treatment-naïve prostate cancer patients is still under debate. Therefore, the present study aimed to evaluate the role of PSMA PET/CT in detecting nodal metastases in a large cohort of men and compare imaging results with the risk of lymph node involvement based on the Roach formula. Methods: In total, 280 men with newly diagnosed prostate carcinoma were included in the present study. For all patients, PSMA PET/CT was performed for primary staging. Median age was 67 y (range, 38-84 y), and 84% of all patients were classified as high-risk according to the d'Amico criteria. The risk of lymph node involvement was calculated using the Roach formula and compared with the PSMA PET/CT results. Results: PSMA-positive nodes were detected in 90 of 280 men (32.1%). Although most nodal metastases occurred within the pelvis, 36.0% were in extrapelvic sites. In 9 patients (3.2%), nodal metastases occurred in the Virchow node. After comparison of PSMA data with the results of the Roach formula, an area under the curve of 0.781 was obtained for the Roach predictions. Conclusion: For treatment-naïve prostate cancer patients, PSMA PET/CT is well suited for the detection of nodal metastases. However, the original Roach formula can still be used for a quick assessment of potential lymphatic spread in daily clinical routine.

Pathologist-level classification of histopathological melanoma images with deep neural networks

BACKGROUND

The diagnosis of most cancers is made by a board-certified pathologist based on a tissue biopsy under the microscope. Recent research reveals a high discordance between individual pathologists. For melanoma, the literature reports 25-26% of discordance for classifying a benign nevus versus malignant melanoma. Deep learning was successfully implemented to enhance the precision of lung and breast cancer diagnoses. The aim of this study is to illustrate the potential of deep learning to assist human assessment for a histopathologic melanoma diagnosis.

METHODS

Six hundred ninety-five lesions were classified by an expert histopathologist in accordance with current guidelines (350 nevi and 345 melanomas). Only the haematoxylin and eosin stained (H&E) slides of these lesions were digitalised using a slide scanner and then randomly cropped. Five hundred ninety-five of the resulting images were used for the training of a convolutional neural network (CNN). The additional 100 H&E image sections were used to test the results of the CNN in comparison with the original class labels.

FINDINGS

The total discordance with the histopathologist was 18% for melanoma (95% confidence interval [CI]: 7.4-28.6%), 20% for nevi (95% CI: 8.9-31.1%) and 19% for the full set of images (95% CI: 11.3-26.7%).

INTERPRETATION

Even in the worst case, the discordance of the CNN was about the same compared with the discordance between human pathologists as reported in the literature. Despite the vastly reduced amount of data, time necessary for diagnosis and cost compared with the pathologist, our CNN archived on-par performance. Conclusively, CNNs indicate to be a valuable tool to assist human melanoma diagnoses.

Deep learning outperformed 136 of 157 dermatologists in a head-to-head dermoscopic melanoma image classification task

BACKGROUND

Recent studies have successfully demonstrated the use of deep-learning algorithms for dermatologist-level classification of suspicious lesions by the use of excessive proprietary image databases and limited numbers of dermatologists. For the first time, the performance of a deep-learning algorithm trained by open-source images exclusively is compared to a large number of dermatologists covering all levels within the clinical hierarchy.

METHODS

We used methods from enhanced deep learning to train a convolutional neural network (CNN) with 12,378 open-source dermoscopic images. We used 100 images to compare the performance of the CNN to that of the 157 dermatologists from 12 university hospitals in Germany. Outperformance of dermatologists by the deep neural network was measured in terms of sensitivity, specificity and receiver operating characteristics.

FINDINGS

The mean sensitivity and specificity achieved by the dermatologists with dermoscopic images was 74.1% (range 40.0%-100%) and 60% (range 21.3%-91.3%), respectively. At a mean sensitivity of 74.1%, the CNN exhibited a mean specificity of 86.5% (range 70.8%-91.3%). At a mean specificity of 60%, a mean sensitivity of 87.5% (range 80%-95%) was achieved by our algorithm. Among the dermatologists, the chief physicians showed the highest mean specificity of 69.2% at a mean sensitivity of 73.3%. With the same high specificity of 69.2%, the CNN had a mean sensitivity of 84.5%.

INTERPRETATION

A CNN trained by open-source images exclusively outperformed 136 of the 157 dermatologists and all the different levels of experience (from junior to chief physicians) in terms of average specificity and sensitivity.

Impact of sialendoscopy on improving health related quality of life in patients suffering from radioiodineinduced xerostomia

Introduction: Xerostomia following radioiodine therapy (RIT) in patients suffering from differentiated thyroid cancer is a common side effect in 2 % to 67 % of patients treated with radioiodine (I-131). In order to evaluate the impact of sialendoscopy on health related quality of life (HRQOL) in patients suffering from therapy induced sialadenitis and xerostomia, we analyzed findings from two dedicated questionnaires (Xerostomy Questionnaire XQ and Xerostomy Inventory XI) in patients before and three months after sialendoscopy. Procedures: In total, 12 patients suffering from differentiated thyroid carcinoma (10 women and 2 men) were evaluated. All patients had experienced conservative management. Patients were offered a sialendoscopy procedure if no major contradictions were present. Patients who denied the procedure formed the control group. Pre- and (three months) postoperative HRQOL was measured with the Patient Reported Outcome Measures (PROM) Xerostomia Questionnaire (XQ) and the Xerostomia Inventory (XI), as well as by a pre- and post-interventional salivary gland scintigram. Patients were graded according to their sialendoscopical findings. Results: Interventional group presented with significant improvements in HRQOL measurements regarding XQ and XI-scores three months postoperatively. Control group showed no significant changes in the XQ or the XI scores. Number of RIT and cumulative activity of I-131 did not correlate with higher disease grade in regards to sialendoscopical findings nor did it correlate with higher XQand XI scores. Pre- and post-interventional salivary gland scintigram stated that parotid glands are more severely damaged than submandibular glands (SMG), but no significant scintigraphically changes could be detected after sialendoscopy. Conclusion: Sialendoscopy in patients suffering from therapy induced sialadenitis and xerostomia seems to be beneficial when evaluating the impact on HRQOL. Functional parameters measured by salivary gland scintigram did not show significant changes in post-interventional scintigrams.

Impact of long-term androgen deprivation therapy on PSMA ligand PET/CT in patients with castration-sensitive prostate cancer

Purpose

Since the introduction of PSMA PET/CT with ⁶⁸Ga-PSMA-11, this modality for imaging prostate cancer (PC) has spread worldwide. Preclinical studies have demonstrated that short-term androgen deprivation therapy (ADT) can significantly increase PSMA expression on PC cells. Additionally, retrospective clinical data in large patient cohorts suggest a positive association between ongoing ADT and a pathological PSMA PET/CT scan. The present evaluation was conducted to further analyse the influence of long-term ADT on PSMA PET/CT findings.

Methods

A retrospective analysis was performed of all 1,704 patients who underwent a ⁶⁸Ga-PSMA-11 PET/CT scan at our institution from 2011 to 2017 to detect PC. Of 306 patients scanned at least twice, 10 had started and continued ADT with a continuous clinical response between the two PSMA PET/CT scans. These ten patients were included in the current analysis which compared the tracer uptake intensity and volume of PC lesions on PSMA PET/CT before and during ongoing ADT.

Results

Overall, 31 PC lesions were visible in all ten patients before initiation of ADT. However, during ongoing ADT (duration 42–369 days, median 230 days), only 14 lesions were visible in eight of the ten patients. The average tracer uptake values decreased in 71% and increased in 12.9% of the PC lesions. Of all lesions, 33.3% were still visible in six patients with a complete PSA response (≤0.1 ng/ml).

Conclusion

Continuous long-term ADT significantly reduces the visibility of castration-sensitive PC on PSMA PET/CT. If the objective is visualization of the maximum possible extent of disease, we recommend referring patients for PSMA PET/CT before starting ADT.

Combining standard clinical blood values for improving survival prediction in patients with newly diagnosed brain metastases-development and validation of the LabBM score

Background

We aimed to investigate the potential of standard hematologic and serum biochemical parameters to provide an independent and substantial contribution to the prediction of survival in patients with newly diagnosed brain metastases (BM).

Methods

Hemoglobin, white blood cell count, platelet count, serum albumin, creatinine, lactate dehydrogenase (LDH), and C-reactive protein (CRP) were assessed at diagnosis of BM in a discovery cohort of 1200 cancer patients. A multivariable Cox regression model was used to derive the LabBM score. The LabBM score was externally validated in an independent cohort consisting of 366 patients.

Results

Hemoglobin below lower limit of normal (<LLN; hazard ratio [HR] 1.28; P = .001), platelet count <LLN (HR: 1.36; P = .013), albumin <LLN (HR: 1.19; P = .038), LDH above upper limit of normal (>ULN; HR: 1.51; P < .001), and CRP >ULN (HR: 1.52; P < .001) were associated with survival in a multivariable Cox regression model and were included in the calculation of the LabBM score. Multivariable analysis including the LabBM score and graded prognostic assessment class revealed an independent and significant association of the LabBM score with overall survival (OS) (HR: 1.42; 95% CI: 1.29-1.57; P < .001). The strong and independent association of LabBM score (HR: 1.93; 95% CI: 1.54-2.42) with OS prognosis was confirmed in the validation cohort.

Conclusion

Standard clinical blood parameters, combined in the easy-to-calculate LabBM score, provide strong and independent prognostic information in patients with BM. The LabBM score is an objective, inexpensive, and reproducible tool to plan clinical management strategies in BM patients and to improve patient selection and stratification for clinical trials.

Abstract 1063: A clear cell renal cancer metastasis model identifies novel mediators of tumor aggressiveness and predictors of patient survival

Clear cell renal cell carcinoma (ccRCC) is the most common subtype of renal cell carcinoma with a 5-year survival rate of only 10.5%, and chemotherapy and radiotherapy regimen have shown limited efficacy. On the molecular level, significant inter- and intra-tumor heterogeneity hamper identification of drug targets, biomarkers and unraveling of disease mechanisms.

We developed a novel patient-derived model system of ccRCC that recapitulates the heterogeneity of the originating cancer enabling us to study ccRCC on a functional level. In five rounds and in three biological replicates of an in vivo selection, we transplanted the metastases of orthotopically transplanted tumor cells into the renal capsules of NOD scid gamma (NSG) mice. The tumor was enriched for cells with higher growth and metastatic potential compared to the initial heterogeneous population. Comparative gene-expression analysis revealed candidate genes associated with enhanced malignant growth and metastasis. Absolute shrinkage and selection operator (LASSO) regression identified a gene signature that can robustly predict patient survival. The prognostic power of our signature was additionally verified in independent patient cohorts suggesting that this approach leverages efficient stratification of patients into distinctive risk groups.

One of the hallmark genes in this signature is known to alter cellular signaling properties. Therefore, we hypothesized that this gene contributes to tumor growth and metastasis and thus to aggressiveness of ccRCC. In fact, in knockdown and overexpression xenografts experiments we could confirm an essential role for tumor aggressiveness in vivo suggesting that the gene and associated downstream signaling pathways are attractive targets for treatment of clear cell renal cancer.

Citation Format: Felix Geist, Teresa Dolt, Thomas Höfner, Corinna Klein, Vanessa Vogel, Albrecht Stenzinger, Tim Holland-Letz, Ornella Kossi, Wilko Weichert, Peter Schirmacher, Sascha Pahernik, Markus Hohenfellner, Andreas Trumpp, Martin Sprick. A clear cell renal cancer metastasis model identifies novel mediators of tumor aggressiveness and predictors of patient survival [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1063.

Evaluation of Promoter Methylation of RASSF1A and ATM in Peripheral Blood of Breast Cancer Patients and Healthy Control Individuals

Breast cancer (BC) is the most common cancer among women and has high mortality rates. Early detection is supposed to be critical for the patient’s prognosis. In recent years, several studies have investigated global DNA methylation profiles and gene-specific DNA methylation in blood-based DNA to develop putative screening markers for cancer. However, most of the studies have not yet been validated. In our study, we analyzed the promoter methylation of RASSF1A and ATM in peripheral blood DNA of 229 sporadic patients and 151 healthy controls by the MassARRAY EpiTYPER assay. There were no significant differences in DNA methylation levels of RASSF1A and ATM between the sporadic BC cases and the healthy controls. Furthermore, we performed the Infinium HumanMethylation450 BeadChip (450K) array analysis using 48 sporadic BC cases and 48 healthy controls (cases and controls are the same from those of the MassARRAY EpiTYPER assay) and made a comparison with the published data. No significant differences were presented in DNA methylation levels of RASSF1A and ATM between the sporadic BC cases and the healthy controls. So far, the evidence for powerful blood-based methylation markers is still limited and the identified markers need to be further validated.

Liquid Profiling of Circulating Tumor DNA in Plasma of Melanoma Patients for Companion Diagnostics and Monitoring of BRAF Inhibitor Therapy

BACKGROUND

The current standard for determining eligibility of patients with metastatic melanoma for BRAF-targeted therapy is tissue-based testing of BRAF mutations. As patients are rarely rebiopsied, detection in blood might be advantageous by enabling a comprehensive assessment of tumor mutational status in real time and thereby representing a noninvasive biomarker for monitoring BRAF therapy.

METHODS

In all, 634 stage I to IV melanoma patients were enrolled at 2 centers, and 1406 plasma samples were prospectively collected. Patients were assigned to 3 separate study cohorts: study 1 for assessment of circulating tumor DNA (ctDNA) as part of companion diagnostics, study 2 for assessment of ctDNA for patients with low tumor burden and for follow-up, and study 3 for monitoring of resistance to BRAF inhibitor (BRAFi) or mitogen-activated protein kinase inhibitor therapy.

RESULTS

Overall, a high degree of concordance between plasma and tissue testing results was observed at 90.9% (study 1) and 90.1% (study 2), respectively. Interestingly, discrepant results were in some cases associated with nonresponse to BRAFi (n = 3) or a secondary BRAF-mutant malignancy (n = 5). Importantly, ctDNA results correlated with the clinical course of disease in 95.7% and with response to treatment. Significantly, the detection of BRAF mutant ctDNA preceded relapse assessed by Response Evaluation Criteria in Solid Tumors, and was more specific than serum S100 and lactate dehydrogenase.

CONCLUSIONS

Blood-based testing compares favorably with standard-of-care tissue-based BRAF mutation testing. Importantly, blood-based BRAF testing correlates with the clinical course, even for early-stage patients, and may be used to predict response to treatment, recurrence, and resistance before radioimaging under BRAFi therapy, thereby enabling considerable improvements in patient treatment.

Intraindividual Comparison of 99mTc-Methylene Diphosphonate and Prostate-Specific Membrane Antigen Ligand 99mTc-MIP-1427 in Patients with Osseous Metastasized Prostate Cancer

The objective of this study was to evaluate the rate of detection of bone metastases obtained with the prostate-specific membrane antigen (PSMA)-targeting tracer ^99mTc-MIP-1427, as opposed to conventional bone scanning with ^99mTc-methylene diphosphonate (^99mTc-MDP), in a collective of patients with known advanced-stage osseous metastasized prostate cancer. Methods: Twenty-one patients with known metastatic disease were staged with both conventional bone scanning and PSMA ligand scintigraphy within a time frame of less than 10 d. Imaging included planar whole-body scanning and SPECT or SPECT/CT with 2 bed positions 3 h after injection of either 500-750 MBq of ^99mTc-MIP-1427 or 600-750 MBq of ^99mTc-MDP. Lesions were scored as typical tumor, equivocal (benign/malignant), or normal within a standard reporting schema divided into defined anatomic regions. Masked and consensus readings were performed with sequential unmasking: planar scans first, then SPECT/CT, the best evaluable comparator (including MRI), PET/CT, and follow-up examinations. Results: Eleven patients had PSMA-positive visceral metastases that were predictably not diagnosed with conventional bone scanning. However, SPECT/CT was required to distinguish between soft-tissue uptake and overlapping bone. Four patients had extensive ^99mTc-MDP-negative bone marrow lesions. Seven patients had superscan characteristics on bone scans; in contrast, the extent of red marrow involvement was more evident on PSMA scans. Only 3 patients had equivalent results on bone scans and PSMA scans. In 16 patients, more suspect lesions were detected with PSMA scanning than with bone scanning. In 2 patients (10%), a PSMA-negative tumor phenotype was present. Conclusion: PSMA scanning provided a clear advantage over bone scanning by reducing the number of equivocal findings in most patients. SPECT/CT was pivotal for differentiating bone metastases from extraosseous tumor lesions.

Circulating free DNA integrity and concentration as independent prognostic markers in metastatic breast cancer

PURPOSE

Non-invasive blood-based molecular markers have been investigated for cancer diagnosis and prognosis. Circulating free or cell-free DNA (cfDNA) variables have been shown to be putative markers in breast cancer prognosis.

METHODS

Here, we investigated the potential prognostic ability of cfDNA concentration and cfDNA integrity (cfDI) in a study cohort of 268 patients by quantitative PCR. We compared cfDNA concentration and cfDI at baseline and after one cycle of therapy in metastatic breast cancer (MBC) patients.

RESULTS

A significantly increased cfDI (P = 1.21E-7 for ALU and P = 1.87E-3 for LINE1) and decreased cfDNA concentration (P = 1.17E-3 for ALU and P = 1.60E-2 for LINE1) in both repetitive DNA elements after one cycle of therapy was observed. A multiple Cox regression model indicated that cfDI and cfDNA concentration can serve as independent prognostic markers in patients at baseline with HR (95% CI) of 0.70 (0.48-1.01) for ALU cfDI, 0.63 (0.44-0.92) for LINE1 cfDI, 2.44 (1.68-3.53) for ALU cfDNA concentration, and 2.12 (1.47-3.06) for LINE1 cfDNA concentration and after one cycle of therapy with HR (95% CI) of 0.59 (0.42-0.84) for ALU cfDI, 0.51 (0.36-0.74) for LINE1 cfDI, 1.59 (1.31-1.92) for ALU cfDNA concentration, and 1.30 (1.17-1.45) for LINE1 cfDNA concentration, respectively. By comparing integrated prediction error of different models, cfDNA variables were shown to improve the prognostic power of the CTC status.

CONCLUSIONS

We hereby show that cfDNA variables, especially in combination with other markers, can serve as attractive prognostic markers for MBC patients at baseline and during the systematic therapy.

Role of CT Density in PET/CT-Based Assessment of Lymphoma

PURPOSE

In patients with Hodgkin (HL) and non-Hodgkin lymphoma (NHL), primary staging, as well as intermediate and late response assessment, is often performed by integrated 2-deoxy-2-[¹⁸F]fluoro-D-glucose ([¹⁸F]FDG) positron emission tomography/X-ray computed tomography (PET/CT). The purpose of this analysis was to evaluate if findings in patients with histopathologically proven HL or NHL might correlate with semi-automated density measurements of target lesions (TLs) in the CT component of the integrated PET/CT examination.

PROCEDURES

After approval by the institutional review board, 176 lymph nodes (LN) in 90 PET/CT examinations of 90 patients were retrospectively analyzed (HL, 108 TLs out of 55 patients; NHL, 68 TLs out of 35 patients). PET/CT was performed for reasons of primary staging, response evaluation as interim PET, or as final examination after therapy, according to the clinical schedule. Analyses of TLs were performed on the basis of tracer uptake (SUV) 60 min after tracer injection and volumetric CT histogram analysis in non-contrast-enhanced CT.

RESULTS

All patients were diagnosed with HL or NHL in a pretreatment biopsy. Prior to therapy induction, staging of all patients was performed using contrast-enhanced CT of the neck to the pelvis, or by [¹⁸F]FDG PET/CT. Of the 176 TLs, 119 were classified as malignant, and 57 were benign. Malignant TLs had significantly higher CT density values compared to benign (p < 0.01).

CONCLUSION

Density measurements of TLs in patients with HL and NHL correlate with the dignity of TLs and might therefore serve as a complementary surrogate parameter for the differentiation between malignant and benign TLs. A possible density threshold in clinical routine might be a 20-Hounsfield units (HU) cutoff value to rule out benignancy in TLs that are above the 20-HU threshold.

Parametric modeling and optimal experimental designs for estimating isobolograms for drug interactions in toxicology

In toxicology and related areas, interaction effects between two substances are commonly expressed through a combination index [Formula: see text] evaluated separately at different effect levels and mixture ratios. Often, these indices are combined into a graphical representation, the isobologram. Instead of estimating the combination indices at the experimental mixture ratios only, we propose a simple parametric model for estimating the underlying interaction function. We integrate this approach into a joint model where both the parameters of the dose-response functions of the singular substances and the interaction parameters can be estimated simultaneously. As an additional benefit, this concept allows to determine optimal statistical designs for combination studies optimizing the estimation of the interaction function as a whole. From an optimal design perspective, finding the interaction parameters generally corresponds to a [Formula: see text]-optimality resp. [Formula: see text]-optimality design problem, while estimation of all underlying dose response parameters corresponds to a [Formula: see text]-optimality design problem. We show how optimal designs can be obtained in either case as well as how combination designs providing reasonable performance in regard to both criteria can be determined by putting a constraint on the efficiency in regard to one of the criteria and optimizing for the other. As all designs require prior information about model parameter values, which may be unreliable in practice, the effect of misspecifications is investigated as well.

The challenge of mapping the human connectome based on diffusion tractography

Tractography based on non-invasive diffusion imaging is central to the study of human brain connectivity. To date, the approach has not been systematically validated in ground truth studies. Based on a simulated human brain data set with ground truth tracts, we organized an open international tractography challenge, which resulted in 96 distinct submissions from 20 research groups. Here, we report the encouraging finding that most state-of-the-art algorithms produce tractograms containing 90% of the ground truth bundles (to at least some extent). However, the same tractograms contain many more invalid than valid bundles, and half of these invalid bundles occur systematically across research groups. Taken together, our results demonstrate and confirm fundamental ambiguities inherent in tract reconstruction based on orientation information alone, which need to be considered when interpreting tractography and connectivity results. Our approach provides a novel framework for estimating reliability of tractography and encourages innovation to address its current limitations.

Though tractography is widely used, it has not been systematically validated. Here, authors report results from 20 groups showing that many tractography algorithms produce both valid and invalid bundles.

Highly efficient destruction of squamous carcinoma cells of the head and neck by photochemical internalization of Ranpirnase

INTRODUCTION

Photochemical Internalization is a novel drug delivery technology for cancer treatment based on the principle of Photodynamic Treatment. Using a photosensitizer that locates in endocytic vesicles membranes of tumor cells, Photochemical internalization enables cytosolic release of endocytosed antitumor agents in a site-specific manner. The purpose of the present in-vitro study was to explore whether Photochemical Internalization is able to enhance the efficacy of Ranpirnase, a cytotoxic amphibian ribonuclease, for eradication of squamous cell carcinoma of the head and neck.

METHODS

Cell viability was measured in 8 primary human cell lines of squamous cell carcinoma of the head and neck after treatment with Ranpirnase and Photochemical Internalization. For Photochemical Internalization the photosensitizer disulfonated tetraphenyl porphine was incubated with tumor cells followed by exposure to blue light (435 nm).

RESULTS

Our study demonstrates significant enhancement of antitumor activity of Ranpirnase by Photochemical Internalization. Treatment responses were heterogeneous between the primary cancer cell lines. Combining Photochemical Internalization with Ranpirnase resulted in 4.6 to 1,940-fold increased cytotoxicity when compared with the ribonuclease alone (P < 0.05).

CONCLUSION

Cytotoxicity of Ranpirnase can be markedly enhanced by Photochemical Internalization in squamous cell carcinoma of the head and neck.

68Ga-PSMA PET/CT and Volumetric Morphology of PET-Positive Lymph Nodes Stratified by Tumor Differentiation of Prostate Cancer

⁶⁸Ga-prostate-specific membrane antigen (PSMA) PET/CT is a new method to detect early nodal metastases in patients with biochemical relapse of prostate cancer. In this retrospective investigation, the dimensions, volume, localization, and SUV_max of nodes identified by ⁶⁸Ga-PSMA were correlated to their Gleason score (GS) at diagnosis. Methods: All PET/CT images were acquired 60 ± 10 min after intravenous injection of ⁶⁸Ga-PSMA (mean dose, 176 MBq). In 147 prostate cancer patients (mean age, 68 y; range, 44-87 y) with prostate-specific antigen relapse (mean prostate-specific antigen level, 5 ng/mL; range, 0.25-294 ng/mL), 362 ⁶⁸Ga-PSMA PET-positive lymph nodes (LNs) were identified. These patients were classified on the basis of their histopathology at primary diagnosis into either low- (GS ≤ 6, well differentiated), intermediate- (GS = 7, moderately differentiated), or high-GS cohorts (GS ≥ 8, poorly differentiated prostate cancer). Using semiautomated LN segmentation software (Fraunhofer MEVIS), we measured node volume and short-axis dimensions (SADs) and long-axis dimensions based on CT and compared with the SUV_max Nodes demonstrating uptake of ⁶⁸Ga-PSMA with an SUV_max of 2.0 or more were considered PSMA-positive, and nodes with an SAD of 8 mm or more were considered positive by morphologic criteria. Results: Mean SUV_max was 13.5 (95% confidence interval [CI], 10.9-16.1), 12.4 (95% CI, 9.9-14.9), and 17.8 (95% CI, 15.4-20.3) within the low-, intermediate-, and high-GS groups, respectively. The morphologic assessment of the ⁶⁸Ga-PSMA-positive LN demonstrated that the low-GS cohort presented with smaller ⁶⁸Ga-PSMA-positive LNs (mean SAD, 7.7 mm; n = 113), followed by intermediate- (mean SAD, 9.4 mm; n = 122) and high-GS cohorts (mean SAD, 9.5 mm; n = 127). On the basis of the CT morphology criteria, only 34% of low-GS patients, 56% of intermediate-GS patients, and 53% of high-GS patients were considered CT positive. Overall, ⁶⁸Ga-PSMA imaging led to a reclassification of stage in 90 patients (61%) from cN0 to cN1 over CT. Conclusion:⁶⁸Ga-PSMA PET is a promising modality in biochemical recurrent prostate cancer patients for N staging. Conventional imaging underestimates LN involvement compared with PSMA molecular staging score in each GS cohort. The sensitivity of ⁶⁸Ga-PSMA PET/CT enables earlier detection of subcentimeter LN metastases in the biochemical recurrence setting.

Repeated PSMA-targeting radioligand therapy of metastatic prostate cancer with 131I-MIP-1095

PURPOSE

Prostate-specific membrane antigen (PSMA)-targeting radioligand therapy (RLT) was introduced in 2011. The first report described the antitumor and side effects of a single dose. The aim of this analysis was to evaluate toxicity and antitumor activity after single and repetitive therapies.

METHODS

Thirty-four men with metastatic castration-resistant prostate cancer received PSMA-RLT with 131I-MIP-1095. Twenty-three patients received a second, and three patients a third dose, timed at PSA progression after an initial response to the preceding therapy. The applied doses were separated in three groups: <3.5, 3.5-5.0 and >5.0 GBq. Antitumor and side-effects were analyzed by blood samples and other clinical data. Follow-up was conducted for up to 5 years.

RESULTS

The best therapeutic effect was achieved by the first therapy. A PSA decline of ≥50% was achieved in 70.6% of the patients. The second and third therapies were significantly less effective. There was neither an association between the applied activity and PSA response or the time-to-progression. Hematologic toxicities were less prevalent but presented in a higher percentage of patients with increasing number of therapies. After hematologic toxicities, xerostomia was the second most frequent side effect and presented more often and with higher intensity after the second or third therapy.

CONCLUSION

The first dose of RLT with 131I-MIP-1095 presented with low side effects and could significantly reduce the tumor burden in a majority of patients. The second and third therapies were less effective and presented with more frequent and more intense side effects, especially hematologic toxicities and xerostomia.