Tumor Rim Research Articles

A New Thermal Damage-Controlled Protocol for Thermal Ablation Modeled with Modified Porous Media-Based Bioheat Equation with Variable Porosity

Thermal ablation of tumors is a minimally invasive technique more and more employed in cancer treatments. The main shortcomings of this technique are, on the one hand, the risk of an incomplete ablation, and on the other hand, the destruction of the surrounding healthy tissue. In this work, thermal ablation of a spherical hepatocellular carcinoma tumor (HCC) surrounded by healthy tissue is modeled. A modified porous media-based bioheat model is employed, including porosity variability from tumor core to healthy tissue, following experimental in vivo measures. Moreover, three different protocols are investigated: a constant heating protocol, a pulsating protocol, and a new developed damage-controlled protocol. The proposed damage-controlled protocol changes the heating source from constant to pulsating according to the thermal damage probability on the tumor rim. The equations are numerically solved by means of the commercial software COMSOL Multiphysics, and the outcomes show that the new proposed protocol is able to achieve the complete ablation in less time than the completely pulsating protocol, and to reach tissue temperature on the tumor rim 10 °C smaller than the constant protocol. These results are relevant to develop and improve different patient-based and automated protocols which can be embedded in medical devices’ software or in mobile applications, supporting medical staff with innovative technical solutions.

Perfusion-Limited Hypoxia Determines the Outcome of Radiation Therapy of Hypoxic Tumours.

Despite advancements in functional imaging, the resolution of modern techniques is still limited with respect to the tumour microenvironment. Radiotherapy strategies to counteract e.g., tumour hypoxia based on functional imaging therefore carry an inherent uncertainty that could compromise the outcome of the treatment. It was the aim of this study to investigate the impact of variations in the radiosensitivity of hypoxic tumours in small regions in comparison to the resolution of current imaging techniques on the probability of obtaining tumour control. A novel in silico model of three-dimensional tumour vasculature and oxygenation was used to model three tumours with different combinations of diffusion-limited, perfusion-limited and anaemic hypoxia. Specifically, cells in the transition region from a tumour core with diffusion-limited hypoxia to the well-oxygenated tumour rim were considered with respect to their differential radiosensitivity depending on the character of the hypoxia. The results showed that if the cells in the transition region were under perfusion-limited hypoxia, the tumour control probability was substantially lower in comparison to the case when the cells were anaemic (or under diffusion-limited hypoxia). This study therefore demonstrates the importance of differentiating between different forms of hypoxia on a scale currently unattainable to functional imaging techniques, lending support to the use and importance of radiobiological modelling of the cellular radiosensitivity and response at microscale.

Contrast Agent Quantification by Using Spatial Information in Dynamic Contrast Enhanced MRI

The purpose of this work is to investigate spatial statistical modelling approaches to improve contrast agent quantification in dynamic contrast enhanced MRI, by utilising the spatial dependence among image voxels. Bayesian hierarchical models (BHMs), such as Besag model and Leroux model, were studied using simulated MRI data. The models were built on smaller images where spatial dependence can be incorporated, and then extended to larger images using the maximum a posteriori (MAP) method. Notable improvements on contrast agent concentration estimation were obtained for both smaller and larger images. For smaller images: the BHMs provided substantial improved estimates in terms of the root mean squared error (rMSE), compared to the estimates from the existing method for a noise level equivalent of a 12-channel head coil at 3T. Moreover, Leroux model outperformed Besag models with two different dependence structures. Specifically, the Besag models increased the estimation precision by 27% around the peak of the dynamic curve, while the Leroux model improved the estimation by 40% at the peak, compared with the existing estimation method. For larger images: the proposed MAP estimators showed clear improvements on rMSE for vessels, tumor rim and white matter.

Brain Distribution of Berzosertib: An Ataxia Telangiectasia and Rad3-Related Protein Inhibitor for the Treatment of Glioblastoma.

The effective treatment of brain tumors is a considerable challenge in part because of the presence of the blood-brain barrier (BBB) that limits drug delivery. Glioblastoma multiforme (GBM) is an aggressive and infiltrative primary brain tumor with an extremely poor prognosis after standard-of-care therapy with surgery, radiotherapy (RT), and chemotherapy. DNA damage response (DDR) pathways play a critical role in DNA repair in cancer cells, and inhibition of these pathways can potentially augment RT and chemotherapy tumor cell toxicity. The ataxia telangiectasia and Rad3-related protein (ATR) kinase is a key regulator of the DDR network and is potently and selectively inhibited by the ATR inhibitor berzosertib. Although in vitro studies demonstrate a synergistic effect of berzosertib in combination with temozolomide, in vivo efficacy studies have yet to recapitulate this observation using intracranial tumor models. In the current study, we demonstrate that delivery of berzosertib to the brain is restricted by efflux at the BBB. Berzosertib has a high binding affinity to brain tissue compared with plasma, thereby leading to low free drug concentrations in the brain. Berzosertib distribution is heterogenous within the tumor, wherein concentrations are substantially lower in normal brain and invasive tumor rim (wherein the BBB is intact) when compared with those in the tumor core (wherein the BBB is leaky). These results demonstrate that high tissue binding and limited and heterogenous brain distribution of berzosertib may be important factors that influence the efficacy of berzosertib therapy in GBM. SIGNIFICANCE STATEMENT: This study examined the brain delivery and efficacy of berzosertib in patient-derived xenograft models of glioblastoma multiforme (GBM). Berzosertib is actively effluxed at the blood-brain barrier and is highly bound to brain tissue, leading to low free drug concentrations in the brain. Berzosertib is heterogeneously distributed into different regions of the brain and tumor and, in this study, was not efficacious in vivo when combined with temozolomide. These factors inform the future clinical utility of berzosertib for GBM.

Improving the accuracy of prognosis for clinical stage I solid lung adenocarcinoma by radiomics models covering tumor per se and peritumoral changes on CT.

To assess methods to improve the accuracy of prognosis for clinical stage I solid lung adenocarcinoma using radiomics based on different volumes of interests (VOIs). This retrospective study included patients with postoperative clinical stage I solid lung adenocarcinoma from two hospitals, center 1 and center 2. Three databases were generated: dataset A (training set from center 1), dataset B (internal test set from center 1), and dataset C (external validation test from center 2). Disease-free survival (DFS) data were collected. CT radiomics models were constructed based on four VOIs: gross tumor volume (GTV), 3 mm external to the tumor border (peritumoral volume [PTV]0~+3), 6 mm crossing tumor border (PTV-3~+3), and 6 mm external to the tumor border (PTV0~+6). The area under the receiver operating characteristic curve (AUC) was used to compare the model accuracies. A total of 334 patients were included (204 and 130 from centers 1 and 2). The model using PTV-3~+3 (AUC 0.81 [95% confidence interval {CI}: 0.75, 0.94], 0.81 [0.63, 0.90] for datasets B and C) outperformed the other three models, GTV (0.73 [0.58, 0.81], 0.73 [0.58, 0.83]), PTV0~+3 (0.76 [0.52, 0.87], 0.75 [0.60, 0.83]), and PTV0~+6 (0.72 [0.60, 0.81], 0.69 [0.59, 0.81]), in datasets B and C, all p < 0.05. A radiomics model based on a VOI of 6 mm crossing tumor border more accurately predicts prognosis of clinical stage I solid lung adenocarcinoma than that based on VOIs including overall tumor or external rims of 3 mm and 6 mm. • Radiomics is a useful approach to improve the accuracy of prognosis for stage I solid adenocarcinoma. • The radiomics model based on VOIs that includes 3 mm within and external to the tumor border (peritumoral volume [PTV]-3~+3) outperformed models that included either only the tumor itself or those that only included the peritumoral volume.

A computational model of glioma reveals opposing, stiffness-sensitive effects of leaky vasculature and tumor growth on tissue mechanical stress and porosity.

A biphasic computational model of a growing, vascularized glioma within brain tissue was developed to account for unique features of gliomas, including soft surrounding brain tissue, their low stiffness relative to brain tissue, and a lack of draining lymphatics. This model is the first to couple nonlinear tissue deformation with porosity and tissue hydraulic conductivity to study the mechanical interaction of leaky vasculature and solid growth in an embedded glioma. The present model showed that leaky vasculature and elevated interstitial fluid pressure produce tensile stress within the tumor in opposition to the compressive stress produced by tumor growth. This tensile effect was more pronounced in softer tissue and resulted in a compressive stress concentration at the tumor rim that increased when tumor was softer than host. Aside from generating solid stress, fluid pressure-driven tissue deformation decreased the effective stiffness of the tumor while growth increased it, potentially leading to elevated stiffness in the tumor rim. A novel prediction of reduced porosity at the tumor rim was corroborated by direct comparison with estimates from our in vivo imaging studies. Antiangiogenic and radiation therapy were simulated by varying vascular leakiness and tissue hydraulic conductivity. These led to greater solid compression and interstitial pressure in the tumor, respectively, the former of which may promote tumor infiltration of the host. Our findings suggest that vascular leakiness has an important influence on in vivo solid stress, stiffness, and porosity fields in gliomas given their unique mechanical microenvironment.

OTEH-2. High-dimensional analysis of spatial immune cell heterogeneity in glioblastoma reveals differences between contrast-enhancing and non-contrast-enhancing tumor rims

BackgroundGlioblastoma (GBM) is the most common primary malignant brain tumor in adults. GBM remains an incurable disease, with a median survival ~20 months. Complex intercellular interactions within the tumor microenvironment and spatial heterogeneity have challenged and impeded therapeutic efficacy. The non-contrast-enhancing (by T1-weighted MRI) rim of GBM is not always safely resectable and represents a major source of recurrence. We hypothesized that differential immune infiltration is an underlying factor of spatial heterogeneity in GBM, particularly in the non-contrast-enhancing tumor rim.MethodsFive patients with newly diagnosed GBM (ages 53–84) were recruited to a device feasibility study (NCT04545177) utilizing an intraoperative high-resolution MRI-based navigation system coupled with the NICO Myriad (a non-ablative semi-automated resection tool) and a coupled automated biological Tissue Preservation System (NICO APS) to sample spatially mapped regions of tumors in a reproducible and minimally destructive manner. We obtained brain tumor tissue from: (a) tumor core, (b) contrast-enhancing tumor rim and (c) non-contrast-enhancing tumor rim. Downstream processing consisted of digestion of tumor tissue (Miltenyi human tumor digestion kit) for subsequent single-cell isolation, viability assessment and immediate staining for multiparametric flow cytometry for immune profiling.ResultsViability varied across sampled regions (median 85%, range 52–100%). With the exception of 1 sample, viability was >70% in all specimens. High-dimensional analysis with 26 marker flow cytometry revealed spatial heterogeneity in the frequency of myeloid-derived suppressor cell subsets, regulatory T cells, CD8+ T cells, as well as expression of T cell activation and exhaustion markers.ConclusionsSemi-automated, spatially mapped intraoperative sampling of GBM with high viability of specimens is feasible and reproducible with the NICO Myriad and APS devices. High-dimensional analysis of immune cells in the GBM microenvironment captured the spatial heterogeneity of GBM. Future studies will expand on these observations by analyzing more patient specimens in combination with multiple omics assays.

Clinical Features and Prognostic Factors of Pediatric Glioblastoma: Report of 38 Cases

To better characterize children with glioblastoma, assess outcomes, and identify prognostic factors associated with overall survival and progression-free survival in a relatively large cohort from a single institution. For this retrospective review, 38 pediatric patients with a diagnosis of glioblastoma who were treated at The First Affiliated Hospital of Zhengzhou University between January 2015 and January 2020 were selected. Clinical and pathological characteristics, imaging, treatment, and survival variables were compared. There were 24 boys and 14 girls with a median age of 11.5 years (range, 3-18 years). All patients underwent surgery, with gross total resection in 16 and subtotal resection in 22. Of patients, 18 received radiation combined with chemotherapy, 6 received radiation or chemotherapy alone, and 14 did not receive any adjuvant therapy. Contrast-enhanced magnetic resonance imaging of 21 patients showed rim enhancement, while heterogeneous enhancement was shown on imaging of the other 17 patients. Tumors were observed in hemispheric locations in 19 cases and in central locations in the others. Median overall survival was 10.5 months with a median progression-free survival of 6 months. Extent of resection, adjuvant therapy, and original site of tumor were identified as independent predictors for progression-free survival and overall survival on multivariate analysis. There were significant differences in prognosis among different enhancement characteristics; patients with rim-enhancing tumors had a better prognosis. Pediatric glioblastoma carries a dismal prognosis. Maximum safe resection followed by adjuvant radiation with chemotherapy is considered standard treatment. Better outcomes are associated with hemispheric tumor locations and rim enhancement on magnetic resonance imaging.

The Histopathologic and Radiologic Features of T2-FLAIR Mismatch Sign in IDH-Mutant 1p/19q Non-codeleted Astrocytomas

The T2-FLAIR mismatch sign is a useful imaging sign in clinical magnetic resonance imaging studies for detecting isocitrate dehydrogenase (IDH)-mutant 1p/19q non-codeleted astrocytomas. However, the association between the mismatch sign and pathologic findings is poorly understood. Therefore, the aim of this study was to elucidate the relationship of histopathologic and radiologic features with the mismatch sign in IDH-mutant 1p/19q non-codeleted astrocytomas. We divided 17 IDH-mutant 1p/19q non-codeleted patients into 2 groups according to mismatch sign presence (WITH, n= 9; WITHOUT, n= 8) and retrospectively analyzed their pathologic findings and apparent diffusion coefficient (ADC) values. We also compared these findings between the tumor Core (central area) and Rim (marginal area). In the pathologic analysis, Core of the WITH group contained numerous microcysts whereas Rim had abundant neuroglial fibrils and cellularity. In contrast, Core of the WITHOUT group had highly concentrated neuroglial fibrils. In ADC analysis, Core of the WITH group had significantly higher ADC values compared with Rim (P < 0.001). However, there was no significant difference between Core and Rim in the WITHOUT group (P= 0.12). The WITH group had a significantly higher Core/Rim ratio of ADC values compared with the WITHOUT group (P < 0.001). This study provides evidence that a region-dependent microstructural difference could reflect the mismatch sign in IDH-mutant 1p/19q non-codeleted astrocytomas. Core of the mismatch sign characteristically had microcystic changes accompanied by higher ADC values, whereas Rim had abundant neuroglial fibrils and cellularity accompanied by lower ADC values.

Abstract PS14-16: Novel iodine nanoparticle micro-localization and resultant radiotherapy-enhancement of triple negative human breast cancer growing in the brains of athymic nude mice

Abstract About 30% of breast cancers metastasize to brain; those widely disseminated are fatal typically in 3-4 months, even with the best available surgery, drugs, and radiotherapy. To address this dire situation, we have developed iodine nanoparticles (INPs) that target brain tumors after intravenous (IV) injection. The iodine then absorbs X-rays during radiotherapy (RT), creating free radicals and local tumor damage, effectively boosting the local RT dose at the tumor. Efficacy was tested using the very aggressive human triple negative breast cancer (TNBC, MDA-MB-231 cells) growing in the brains of athymic nude mice. With a well-tolerated non-toxic IV dose of the INPs (7 g iodine/kg body weight), tumors showed a heavily iodinated rim surrounding the tumor having an average uptake of 2.9% iodine by weight (peaks at 4.5%), calculated to provide dose enhancement factors of ~5.5 (peaks at 8.0) – the highest ever reported for any radio-enhancing agents. With 15-Gy, single dose RT, all animals died by 72 days; INP pretreatment resulted in longer-term remissions with 40% of mice surviving 150 days and 30% surviving &amp;gt; 280 days (Hainfeld et al., 2020). Fluorescence confocal microscopy revealed most INP staining co-localized with CD31 in the tumor center and tumor periphery. Greatest INP and CD31 staining was in the tumor periphery, the region of increased Micro CT contrast. Tumor cells are seen to line irregularly-shaped spaces (ISS) with INP and CD31 staining very close to or on the tumor cell surface and with PAS stain on their boundary and may represent a unique form of CD31-expressing vascular mimicry in intracerebral 231-tumors. INP and CD31 co-staining is also seen around ISS formed around tumor cells migrating on CD31 positive blood-vessels. We hypothesize that breast cancer cells secrete a CD31 containing scaffold to which IV-injected INPs bind; tumor cells proliferate along the scaffold forming the boundaries of the ISS creating a form of vascular mimicry. The significant radiation dose enhancement to the prolific INP-binding ISS found throughout the tumor but concentrated in the tumor rim, may contribute significantly to the life extensions observed after INP-RT; vascular mimicry could represent a new nanoparticle, particularly INP, tumor-homing target. Citation Format: Sharif M Ridwan, James F Hainfeld, Yaroslav Stanishevskiy, Vanessa Ross, Henry M Smilowitz. Novel iodine nanoparticle micro-localization and resultant radiotherapy-enhancement of triple negative human breast cancer growing in the brains of athymic nude mice [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS14-16.

High-frequency electrical properties tomography at 9.4T as a novel contrast mechanism for brain tumors.

PurposeTo establish high‐frequency magnetic resonance electrical properties tomography (MREPT) as a novel contrast mechanism for the assessment of glioblastomas using a rat brain tumor model.MethodsSix F98 intracranial tumor bearing rats were imaged longitudinally 8, 11 and 14 days after tumor cell inoculation. Conductivity and mean diffusivity maps were generated using MREPT and Diffusion Tensor Imaging. These maps were co‐registered with T2‐weighted images and volumes of interests (VOIs) were segmented from the normal brain, ventricles, edema, viable tumor, tumor rim, and tumor core regions. Longitudinal changes in conductivity and mean diffusivity (MD) values were compared in these regions. A correlation analysis was also performed between conductivity and mean diffusivity values.ResultsThe conductivity of ventricles, edematous area and tumor regions (tumor rim, viable tumor, tumor core) was significantly higher (P < .01) compared to the contralateral cortex. The conductivity of the tumor increased over time while MD from the tumor did not change. A marginal positive correlation was noted between conductivity and MD values for tumor rim and viable tumor, whereas this correlation was negative for the tumor core.ConclusionWe demonstrate a novel contrast mechanism based on ionic concentration and mobility, which may aid in providing complementary information to water diffusion in probing the microenvironment of brain tumors.

Novel Iodine nanoparticles target vascular mimicry in intracerebral triple negative human MDA-MB-231 breast tumors

Triple negative breast cancer (TNBC), ~ 10–20% of diagnosed breast cancers, metastasizes to brain, lungs, liver. Iodine nanoparticle (INP) radioenhancers specifically localize to human TNBC MDA-MB-231 tumors growing in mouse brains after iv injection, significantly extending survival of mice after radiation therapy (RT). A prominent rim of INP contrast (MicroCT) previously seen in subcutaneous tumors but not intracerebral gliomas, provide calculated X-ray dose-enhancements up to > eightfold. Here, MDA-MB-231-cells, INPs, CD31 were examined by fluorescence confocal microscopy. Most INP staining co-localized with CD31 in the tumor center and periphery. Greatest INP/CD31 staining was in the tumor periphery, the region of increased MicroCT contrast. Tumor cells are seen to line irregularly-shaped spaces (ISS) with INP, CD31 staining very close to or on the tumor cell surface and PAS stain on their boundary and may represent a unique form of CD31-expressing vascular mimicry in intracerebral 231-tumors. INP/CD31 co-staining is also seen around ISS formed around tumor cells migrating on CD31+ blood-vessels. The significant radiation dose enhancement to the prolific collagen I containing, INP-binding ISS found throughout the tumor but concentrated in the tumor rim, may contribute significantly to the life extensions observed after INP-RT; VM could represent a new drug/NP, particularly INP, tumor-homing target.

Small Animal IMRT Using 3D-Printed Compensators

Preclinical radiation replicating clinical intensity modulated radiation therapy (IMRT) techniques can provide data translatable to clinical practice. For this work, treatment plans were created for oxygen-guided dose-painting in small animals using inverse-planned IMRT. Spatially varying beam intensities were achieved using 3-dimensional (3D)-printed compensators. Optimized beam fluence from arbitrary gantry angles was determined using a verified model of the XRAD225Cx treatment beam. Compensators were 3D-printed with varied thickness to provide desired attenuation using copper/polylactic-acid. Spatial resolution capabilities were investigated using printed test-patterns. Following American Association of Physicists in Medicine TG119, a 5-beam IMRT plan was created for a miniaturized (∼1/8th scale) C-shape target. Electron paramagnetic resonance imaging of murine tumor oxygenation guided simultaneous integrated boost (SIB) plans conformally treating tumor to a base dose (Rx1) with boost (Rx2) based on tumor oxygenation. The 3D-printed compensator intensity modulation accuracy and precision was evaluated by individually delivering each field to a phantom containing radiochromic film and subsequent per-field gamma analysis. The methodology was validated end-to-end with composite delivery (incorporating 3D-printed tungsten/polylactic-acid beam trimmers to reduce out-of-field leakage) of the oxygen-guided SIB plan to a phantom containing film and subsequent gamma analysis. Resolution test-patterns demonstrate practical printer resolution of ∼0.7 mm, corresponding to 1.0 mm bixels at the isocenter. The miniaturized C-shape plan provides planning target volume coverage (V95% = 95%) with organ sparing (organs at risk Dmax < 50%). The SIB plan to hypoxic tumor demonstrates the utility of this approach (hypoxic tumor V95%,Rx2 = 91.6%, normoxic tumor V95%,Rx1 = 95.7%, normal tissue V100%,Rx1 = 7.1%). The more challenging SIB plan to boost the normoxic tumor rim achieved normoxic tumor V95%,Rx2 = 90.9%, hypoxic tumor V95%,Rx1 = 62.7%, and normal tissue V100%,Rx2 = 5.3%. Average per-field gamma passing rates using 3%/1.0 mm, 3%/0.7 mm, and 3%/0.5 mm criteria were 98.8% ± 2.8%, 96.6% ± 4.1%, and 90.6% ± 5.9%, respectively. Composite delivery of the hypoxia boost plan and gamma analysis (3%/1 mm) gave passing results of 95.3% and 98.1% for the 2 measured orthogonal dose planes. This simple and cost-effective approach using 3D-printed compensators for small-animal IMRT provides a methodology enabling preclinical studies that can be readily translated into the clinic. The presented oxygen-guided dose-painting demonstrates that this methodology will facilitate studies driving much needed biologic personalization of radiation therapy for improvements in patient outcomes.

EXTH-03. IODINE NANOPARTICLE RADIOTHERAPY OF HUMAN BREAST CANCER GROWING IN THE BRAINS OF ATHYMIC MICE

Abstract About 30% of breast cancers metastasize to brain; those widely disseminated are fatal typically in 3–4 months, even with the best available surgery, drugs, and radiotherapy. To address this dire situation, we have developed iodine nanoparticles (INPs) that target brain tumors after intravenous (IV) injection. The iodine then absorbs X-rays during radiotherapy (RT), creating free radicals and local tumor damage, effectively boosting the local RT dose at the tumor. Efficacy was tested using the very aggressive human triple negative breast cancer (TNBC, MDA-MB-231 cells) growing in the brains of athymic nude mice. With a well-tolerated non-toxic IV dose of the INPs (7 g iodine/kg body weight), tumors showed a heavily iodinated rim surrounding the tumor having an average uptake of 2.9% iodine by weight (peaks at 4.5%), calculated to provide dose enhancement factors of ~5.5 (peaks at 8.0) -- the highest ever reported for any radio-sensitizing agents. With 15 Gy, single dose RT, all animals died by 72 days; INP pretreatment resulted in longer-term remissions with 40% of mice surviving 150 days and 30% surviving &amp;gt; 280 days. Fluorescence confocal microscopy revealed most INP staining co-localized with CD31in the tumor center and periphery. Greatest INP/CD31 staining was in the tumor periphery, the region of increased MicroCT contrast. Tumor cells line irregularly-shaped spaces (ISS) with INP, CD31 staining very close to or on the tumor cell surface and PAS stain on their boundary and may represent a unique form of CD31-expressing vascular mimicry in intracerebral 231-tumors. INP/CD31 co-staining is also seen around ISS formed around tumor cells migrating on CD31+blood-vessels. The significant radiation dose enhancement to the prolific INP-binding ISS found throughout the tumor but concentrated in the tumor rim, may contribute significantly to the life extensions observed after INP-RT; VM could represent a new NP, particularly INP, tumor-homing target.

Comprehensive Analysis of Tumour Sub-Volumes for Radiomic Risk Modelling in Locally Advanced HNSCC.

Simple SummaryRadiomic risk models are usually based on imaging features, which are extracted from the entire gross tumour volume (GTV). This approach does not explicitly consider the complex biological structure of the tumours. Therefore, in this retrospective study, we investigated the prognostic value of radiomic analyses based on different tumour sub-volumes using computed tomography imaging of patients with locally advanced head and neck squamous cell carcinoma who were treated with primary radio-chemotherapy. The GTV was cropped by different margins to define the rim and corresponding core sub-volumes of the tumour. Furthermore, the best performing tumour rim sub-volume was extended into surrounding tissue with different margins. As a result, the models based on the 5 mm tumour rim and on the 3 mm extended rim sub-volume showed an improved performance compared to models based on the corresponding tumour core. This indicates that the consideration of tumour sub-volumes may help to improve radiomic risk models.Imaging features for radiomic analyses are commonly calculated from the entire gross tumour volume (GTV). However, tumours are biologically complex and the consideration of different tumour regions in radiomic models may lead to an improved outcome prediction. Therefore, we investigated the prognostic value of radiomic analyses based on different tumour sub-volumes using computed tomography imaging of patients with locally advanced head and neck squamous cell carcinoma. The GTV was cropped by different margins to define the rim and the corresponding core sub-volumes of the tumour. Subsequently, the best performing tumour rim sub-volume was extended into surrounding tissue with different margins. Radiomic risk models were developed and validated using a retrospective cohort consisting of 291 patients in one of the six Partner Sites of the German Cancer Consortium Radiation Oncology Group treated between 2005 and 2013. The validation concordance index (C-index) averaged over all applied learning algorithms and feature selection methods using the GTV achieved a moderate prognostic performance for loco-regional tumour control (C-index: 0.61 ± 0.04 (mean ± std)). The models based on the 5 mm tumour rim and on the 3 mm extended rim sub-volume showed higher median performances (C-index: 0.65 ± 0.02 and 0.64 ± 0.05, respectively), while models based on the corresponding tumour core volumes performed less (C-index: 0.59 ± 0.01). The difference in C-index between the 5 mm tumour rim and the corresponding core volume showed a statistical trend (p = 0.10). After additional prospective validation, the consideration of tumour sub-volumes may be a promising way to improve prognostic radiomic risk models.

Abstract 3871: Infiltration of CD56dim NK cells regulated by MLH1 into tumor tissue of FAP patients predict better prognosis

Abstract Backgroud Familial adenomatous polyposis (FAP) is an autosomal dominant-inherited colorectal cancer (CRC) with poor prognosis, and is also considered as model to study the change of CRC from pre-tumor to tumor progression. To better predict and guide clinical applications of immune check point inhibitors(ICI), researchers proposed the classification system of human cancer, termed tumor immunity in the microenvironment (TIME), that four different TIME groups have been identified according to the presence of TILs and B7-H1(PD-L1) expression in tumor biopsies. Therefore, we followed and performed this theory into our research about TIME of FAP, to explore the potential of immunotherapy for FAP, and explore the cancerous mechanism from immune microenvironment. Methods We collected tissue samples of 40 FAP patients from May 2009 to December 2018, followed by detection of PD-L1 by using Dako PD-L1 IHC 22C3 pharmDx, MLH1, PMS2, MSH2, MSH6 were detected by IHC, and CD8+ T cells, tumor associated macrophages (TAM) and NK cells infiltration in the tumor biopsies by multiple fluorescence immunohistochemistry (mICH). Follow-up data of these 40 patients were analyzed. Results CD8+T cells, M1 and M2 TAM, CD56bright NK and CD56dim NK cells were found both in intratumoral region and tumor rim of FAP patients(n=40), no differences have been found between M1and M2 TAM, however, CD56dim NK increased more than CD56bright NK both in intratumoral region and tumor rim(p&amp;lt;0.01). Surprisingly, no positive expression of PD-L1 was detected in the tumor tissue of these FAP patients (Tumor Proportion Score, TPS&amp;lt;1%). Further results shown CD56dim NK mainly increased in the tissue of FAP patients(n=7) with loss of MLH1, and consistent with this, these patients shown better prognosis than patients with wild type MLH1, that is, have longer progression free survival (p&amp;lt;0.005). Conclusions For the TIME characteristics of FAP patient, Immunotherapy targeted PD-1/PD-L1 may not applicable for FAP, however, MLH1, the member of mismatch repair protein, was associated with infiltration of NK cells, especially CD56dim NK cells in the tumor, and also associated with prognosis of FAP patients. Therefore, it can be exploited as potential target of immunotherapy for FAP or even CRC. Citation Format: Jun Yang, Hushan Zhang, Wei Qing Liu, Wenliang Li, Shumin Ma, Lei Liang, Zhiyong Kou, Depei Huang, Xudong Shen, Jian Dong. Infiltration of CD56dim NK cells regulated by MLH1 into tumor tissue of FAP patients predict better prognosis [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 3871.

Enhancing Brain Retention of a KIF11 Inhibitor Significantly Improves its Efficacy in a Mouse Model of Glioblastoma

Glioblastoma, the most lethal primary brain cancer, is extremely proliferative and invasive. Tumor cells at tumor/brain-interface often exist behind a functionally intact blood-brain barrier (BBB), and so are shielded from exposure to therapeutic drug concentrations. An ideal glioblastoma treatment needs to engage targets that drive proliferation as well as invasion, with brain penetrant therapies. One such target is the mitotic kinesin KIF11, which can be inhibited with ispinesib, a potent molecularly-targeted drug. Although, achieving durable brain exposures of ispinesib is critical for adequate tumor cell engagement during mitosis, when tumor cells are vulnerable, for efficacy. Our results demonstrate that the delivery of ispinesib is restricted by P-gp and Bcrp efflux at BBB. Thereby, ispinesib distribution is heterogeneous with concentrations substantially lower in invasive tumor rim (intact BBB) compared to glioblastoma core (disrupted BBB). We further find that elacridar—a P-gp and Bcrp inhibitor—improves brain accumulation of ispinesib, resulting in remarkably reduced tumor growth and extended survival in a rodent model of glioblastoma. Such observations show the benefits and feasibility of pairing a potentially ideal treatment with a compound that improves its brain accumulation, and supports use of this strategy in clinical exploration of cell cycle-targeting therapies in brain cancers.

T2/FLAIR-mismatch sign for noninvasive detection of IDH-mutant 1p/19q non-codeleted gliomas: validity and pathophysiology.

BackgroundThis study aimed to assess the validity and pathophysiology of the T2/FLAIR-mismatch sign for noninvasive identification of isocitrate dehydrogenase (IDH)-mutant 1p/19q non-codeleted glioma.MethodsMagnetic resonance imaging scans from 408 consecutive patients with newly diagnosed glioma (113 lower-grade gliomas and 295 glioblastomas) were evaluated for the presence of T2/FLAIR-mismatch sign by 2 independent reviewers. Sensitivity, specificity, accuracy, positive predictive value (PPV), and negative predictive value (NPV) were calculated to assess the performance of the T2/FLAIR-mismatch sign for identifying IDH-mutant 1p/19q non-codeleted tumors. An exploratory analysis of differences in contrast-enhancing tumor volumes, apparent diffusion coefficient (ADC) values, and relative cerebral blood volume (rCBV) values in IDH-mutant gliomas with versus without the presence of a T2/FLAIR-mismatch sign (as well as analysis of spatial differences within tumors with the presence of a T2/FLAIR-mismatch sign) was performed.ResultsThe T2/FLAIR-mismatch sign was present in 12 cases with lower-grade glioma (10.6%), all of them being IDH-mutant 1p/19q non-codeleted tumors (sensitivity = 10.9%, specificity = 100%, PPV = 100%, NPV = 3.0%, accuracy = 13.3%). There was a substantial interrater agreement to identify the T2/FLAIR-mismatch sign (Cohen’s kappa = 0.75 [95% CI, 0.57–0.93]). The T2/FLAIR-mismatch sign was not identified in any other molecular subgroup, including IDH-mutant glioblastoma cases (n = 5). IDH-mutant gliomas with a T2/FLAIR-mismatch sign showed significantly higher ADC (P < .0001) and lower rCBV values (P = .0123) as compared to IDH-mutant gliomas without a T2/FLAIR-mismatch sign. Moreover, in IDH-mutant gliomas with T2/FLAIR-mismatch sign the ADC values were significantly lower in the FLAIR-hyperintense rim as compared to the FLAIR-hypointense core of the tumor (P = .0005).ConclusionsThis study confirms the high specificity of the T2/FLAIR-mismatch sign for noninvasive identification of IDH-mutant 1p/19q non-codeleted gliomas; however, sensitivity is low and applicability is limited to lower-grade gliomas. Whether the higher ADC and lower rCBV values in IDH-mutant gliomas with a T2/FLAIR-mismatch sign (as compared to those without) translate into a measurable prognostic effect requires investigation in future studies. Moreover, spatial differences in ADC values between the core and rim of tumors with a T2/FLAIR-mismatch sign potentially reflect specific distinctions in tumor cellularity and microenvironment.

Dual inhibition of PFKFB3 and VEGF normalizes tumor vasculature, reduces lactate production, and improves chemotherapy in glioblastoma: insights from protein expression profiling and MRI.

Rationale: Tumor vascular normalization (TVN) is emerging to enhance the efficacy of anticancer treatment in many cancers including glioblastoma (GBM). However, a common and severe challenge being currently faced is the transient TVN effect, hampering the sustained administration of anticancer therapy during TVN window. Additionally, the lack of non-contrast agent-based imaging biomarkers to monitor TVN process postpones the clinical translation of TVN strategy. In this study, we investigated whether dual inhibition of VEGF and the glycolytic activator PFKFB3 could reinforce the TVN effect in GBM. Dynamic contrast-enhanced-magnetic resonance imaging (DCE-MRI) and intravoxel incoherent motion (IVIM)-MRI were performed to monitor TVN process and to identify whether IVIM-MRI is a candidate or complementary imaging biomarker for monitoring TVN window without exogenous contrast agent administration.Methods: Patient-derived orthotopic GBM xenografts in mice were established and treated with bevacizumab (BEV), 3PO (PFKFB3 inhibitor), BEV+3PO dual therapy, or saline. The vascular morphology, tumor hypoxia, and lactate level were evaluated before and at different time points after treatments. Doxorubicin was used to evaluate chemotherapeutic efficacy and drug delivery. Microarray of angiogenesis cytokines and western blotting were conducted to characterize post-treatment molecular profiling. TVN process was monitored by DCE- and IVIM-MRI. Correlation analysis of pathological indicators and MRI parameters was further analyzed.Results: Dual therapy extended survival and delayed tumor growth over each therapy alone, concomitant with a decrease of cell proliferation and an increase of cell apoptosis. The dual therapy reinforces TVN effect, thereby alleviating tumor hypoxia, reducing lactate production, and improving the efficacy and delivery of doxorubicin. Mechanistically, several angiogenic cytokines and pathways were downregulated after dual therapy. Notably, dual therapy inhibited Tie1 expression, the key regulator of TVN, in both endothelial cells and tumor cells. DCE- and IVIM-MRI data showed that dual therapy induced a more homogenous and prominent TVN effect characterized by improved vascular function in tumor core and tumor rim. Correlation analysis revealed that IVIM-MRI parameter D* had better correlations with TVN pathological indicators compared with the DCE-MRI parameter Ktrans.Conclusions: Our results propose a rationale to overcome the current limitation of BEV monotherapy by integrating the synergistic effects of VEGF and PFKFB3 blockade to enhance chemotherapy efficacy through a sustained TVN effect. Moreover, we unveil IVIM-MRI parameter D* has much potential as a complementary imaging biomarker to monitor TVN window more precisely without exogenous contrast agent injection.

Spatial heterogeneity of cell-matrix adhesive forces predicts human glioblastoma migration.

BackgroundGlioblastoma (GBM) is a highly aggressive incurable brain tumor. The main cause of mortality in GBM patients is the invasive rim of cells migrating away from the main tumor mass and invading healthy parts of the brain. Although the motion is driven by forces, our current understanding of the physical factors involved in glioma infiltration remains limited. This study aims to investigate the adhesion properties within and between patients’ tumors on a cellular level and test whether these properties correlate with cell migration.MethodsSix tissue samples were taken from spatially separated sections during 5-aminolevulinic acid (5-ALA) fluorescence-guided surgery. Navigated biopsy samples were collected from strongly fluorescent tumor cores, a weak fluorescent tumor rim, and nonfluorescent tumor margins. A microfluidics device was built to induce controlled shear forces to detach cells from monolayer cultures. Cells were cultured on low modulus polydimethylsiloxane representative of the stiffness of brain tissue. Cell migration and morphology were then obtained using time-lapse microscopy.ResultsGBM cell populations from different tumor fractions of the same patient exhibited different migratory and adhesive behaviors. These differences were associated with sampling location and amount of 5-ALA fluorescence. Cells derived from weak- and nonfluorescent tumor tissue were smaller, adhered less well, and migrated quicker than cells derived from strongly fluorescent tumor mass.ConclusionsGBM tumors are biomechanically heterogeneous. Selecting multiple populations and broad location sampling are therefore important to consider for drug testing.