CCRG-04. TARGETING THE CELL-CYCLE EFFECTS OF TUMOR TREATING FIELDS (TTFIELDS) TO INCREASE ITS EFFICACY

Tumor Treating Fields (TTFields) are a novel, non-invasive FDA-approved treatment modality for glioblastoma (GBM) that utilises alternating electric fields. Our research aims to elucidate the effect of TTFields on the cell cycle to advance the understanding of TTFields and find novel targets for increasing its efficacy. We studied the cell cycle progression using live-cell imaging (inovitro Live™) of PIP-FUCCI-transduced GBM cells, EdU incorporation, RPA foci and fiber assay (in U251-MG, SNB-19, A172). These tools allow us to track individual cells evaluate the time spent in each cell cycle phase, and study the ultimate cell fate in control and treatment conditions concerning the cell cycle and replication fork dynamics. Statistical testing was performed by 2-way ANOVA, Tukey-corrected for multiple comparisons, and Kruskal-Wallis test. TTFields causes an immediate delay in S and G2 cell cycle phase, with a subsequent G1 arrest. Wee1 inhibition by AZD1775 forces cells through S-phase and abrogates the subsequent TTFields-induced G2-checkpoint, preventing DNA repair. Combined treatment with TTFields and AZD1775 led to decreased incorporation of EdU and an increase in S-phase-specific phospho-RPA foci. TTFields reduced significantly the DNA fiber length after 12, 24, 48 and 72 hrs of exposure (10.2, 8.3, 7.1 and 5.6 vs 13 um), with also an increase in replication fork asymmetry at these time points (0.56, 0.45, 0.49, and 0.47 vs 0.9 ratio) respectively. CombiningTTFields with either Wee1, ATR, or Chk1 inhibition synergistically decreased clonogenic survival. TTFields induced cell cycle effects with the induction of replication stress, which is aggravated by inhibition of Wee1. Additionally, Wee1, ATR, and Chk1 inhibition dramatically boost the efficacy of TTFields in vitro. This combination strategy has promising clinical potential and will be tested in vivo in different GBM xenografts.

Cell signaling and signaling pathways

NIMG-40. RAPID EARLY PROGRESSION (REP) OF GLIOBLASTOMA IS AN INDEPENDENT NEGATIVE PROGNOSTIC FACTOR: RESULTS FROM A SYSTEMATIC REVIEW AND META-ANALYSIS

INTRODUCTION

In patients with newly-diagnosed glioblastoma, rapid early progression (REP) refers to tumour regrowth between surgery and postoperative chemoradiotherapy. This systematic review and meta-analysis appraised published data on REP to better characterise and understand it.

METHODS

Systematic searches of MEDLINE, EMBASE and the Cochrane database from inception to 21/10/21. Studies describing the incidence of REP – tumour growth between the postoperative MRI scan and pre-radiotherapy MRI scan in newly-diagnosed glioblastoma, were included. The primary outcome was REP incidence.

RESULTS

From 1590 search results, 9 studies were included with 716 patients. The median age was 56.9 years (IQR 54.0-58.8 years). There was a male predominance with a median male-to-female ratio of 1.4 (IQR 1.1-1.5). The median number of days between MRI scans was 34 days (IQR 18-45 days). The mean incidence rate of REP was 45.9% (range 19.3%-72.0%) and significantly lower in studies employing functional imaging to define REP (p< 0.001). REP/non-REP groups were comparable with respect to age (p=0.99), gender (p=0.33) and time between scans (p=0.81). REP was associated with shortened overall survival (HR 1.78, 95% CI 1.30-2.43, p< 0.001), shortened progression-free survival (HR 1.78, 95% CI 1.30-2.43, p< 0.001), subtotal resection (OR 6.96, 95% CI 4-51-10.73, p< 0.001) and IDH wildtype versus mutant tumours (OR 0.20, 95% CI 0.02-0.38, p=0.03). MGMT promoter methylation was not associated with REP (OR 1.29, 95% CI 0.72-2.28, p=0.39).

CONCLUSIONS

REP occurs in almost half of patients with newly-diagnosed glioblastoma and has a strongly negative prognostic effect. Future studies should investigate its biology and effective treatment strategies.

Prolonged Transfusion-Dependent Temozolomide-Induced Thrombocytopaenia in Glioblastoma: Risk Factors Remain Elusive

AIMS

Temozolomide-induced thrombocytopaenia is well-recognised; clinical-course varies widely. Aims: To identify risk factors for prolonged thrombocytopaenia; improve patient-care; inform trial design.

METHOD

Glioblastoma (GBM) patients requiring platelet transfusion were identified. (Local policy: transfuse when plt count ≤ 30 x 109/L). Inclusion criteria: First-line-standard-of-care temozolomide-chemo-radiotherapy (TMZ-CRT). Case-notes reviewed for demographics, blood-counts, radiotherapy and treatment parameters. Thrombocytopaenia grading: CTCAE V5. Date of onset measured from start of TMZ-CRT to date of platelets < 100 x 109/L, and to date of first instance of ≥ grade 3 thrombocytopaenia. Thrombocytopaenia duration: time to platelet count recovery to ≥ 100x109/L.

RESULTS

Between 2017-2021, 69 patients required platelet transfusion; 68/69 identified on routine monitoring. 49 patients were analysed (6:no CRT; 5:trial study drug; 7:≥ 2nd line treatment; 2:inadequate data). Median age: 59 (range 25-73); 61% female. First incidence of thrombocytopaenia during concurrent TMZ-CRT: 27/49 patients; during adjuvant TMZ in 22/49 (13/22 following 6-week-TMZ-CRT, 9/22 following 3-week-TMZ-CRT). In concurrent patients, median time to thrombocytopaenia: 33 days (range 23-38); median duration: 44 days (range 20-105; 5 not recovered); number of transfusions: 1-2:9 pts; 3-4:6pts; 5-7:3pts; 8-10:7pts; >10:2pts. Of 22 adjuvant patients transfused, 8/22 developed ≥G3 thrombocytopaenia post-cycle-2; 19/22 resolved after 1 or 2 transfusions. Thrombocyopaenia was associated with ≥G3 neutropaenia in 11% of patients requiring <5 transfusions vs 75% requiring ≥ 5. Comparison of < 5 vs ≥ 5 transfusion-patients did not identify differences in any demographic or treatment parameters.

CONCLUSION

Risk factors for prolonged TMZ-induced thrombocytopenia vs swiftly-resolving thrombocytopaenia remain elusive. This needs to be reflected in consent processes and in design of clinical trials.

Rapid Early Progression (REP) of Glioblastoma Is an Independent Negative Prognostic Factor: Results From a Systematic Review and Meta-Analysis

AIMS

In patients with newly-diagnosed glioblastoma, rapid early progression (REP) refers to tumour regrowth between surgery and postoperative chemoradiotherapy. This systematic review and meta-analysis aimed to appraise published data on REP to better characterise and understand this phenomenon.

METHOD

Systematic searches of MEDLINE, EMBASE and the Cochrane database from inception to 21/10/21. Studies describing the incidence of REP – tumour growth between the postoperative MRI scan and pre-radiotherapy MRI scan in newly-diagnosed glioblastoma, were included. The primary outcome was REP incidence.

RESULTS

From 1590 search results, 9 studies were included with 716 patients. The median age was 56.9 years (IQR 54.0- 58.8 years). There was a male predominance with a median male-to-female ratio of 1.4 (IQR 1.1-1.5). The median number of days between MRI scans was 34 days (IQR 18-45 days). The mean incidence rate of REP was 45.9% (range 19.3%-72.0%) and significantly lower in studies employing functional imaging to define REP (p<0.001). REP/non-REP groups were comparable with respect to age (p=0.99), gender (p=0.33) and time between scans (p=0.81). REP was associated with shortened overall survival (HR 1.78, 95% CI 1.30-2.43, p<0.001), shortened progression-free survival (HR 1.78, 95% CI 1.30-2.43, p<0.001), subtotal resection (OR 6.96, 95% CI 4-51-10.73, p<0.001) and IDH wildtype versus mutant tumours (OR 0.20, 95% CI 0.02-0.38, p=0.03). MGMT promoter methylation was not associated with REP (OR 1.29, 95% CI 0.72-2.28, p=0.39).

CONCLUSION

REP occurs in almost half of patients with newly-diagnosed glioblastoma and has a strongly negative prognostic effect. Future studies should investigate its biology and effective treatment strategies.

Estimating the percentage of patients who might benefit from proton beam therapy instead of X-ray radiotherapy

OBJECTIVES

High-energy Proton Beam Therapy (PBT) commenced in England in 2018 and NHS England commissions PBT for 1.5% of patients receiving radical radiotherapy. We sought expert opinion on the level of provision.

METHODS

Invitations were sent to 41 colleagues working in PBT, most at one UK centre, to contribute by completing a spreadsheet. 39 responded: 23 (59%) completed the spreadsheet; 16 (41%) declined, arguing that clinical outcome data are lacking, but joined six additional site-specialist oncologists for two consensus meetings. The spreadsheet was pre-populated with incidence data from Cancer Research UK and radiotherapy use data from the National Cancer Registration and Analysis Service. 'Mechanisms of Benefit' of reduced growth impairment, reduced toxicity, dose escalation and reduced second cancer risk were examined.

RESULTS

The most reliable figure for percentage of radical radiotherapy patients likely to benefit from PBT was that agreed by 95% of the 23 respondents at 4.3%, slightly larger than current provision. The median was 15% (range 4-92%) and consensus median 13%. The biggest estimated potential benefit was from reducing toxicity, median benefit to 15% (range 4-92%), followed by dose escalation median 3% (range 0 to 47%); consensus values were 12 and 3%. Reduced growth impairment and reduced second cancer risk were calculated to benefit 0.5% and 0.1%.

CONCLUSIONS

The most secure estimate of percentage benefit was 4.3% but insufficient clinical outcome data exist for confident estimates. The study supports the NHS approach of using the evidence base and developing it through randomised trials, non-randomised studies and outcomes tracking.

ADVANCES IN KNOWLEDGE

Less is known about the percentage of patients who may benefit from PBT than is generally acknowledged. Expert opinion varies widely. Insufficient clinical outcome data exist to provide robust estimates. Considerable further work is needed to address this, including international collaboration; much is already underway but will take time to provide mature data.

[Treatment options for patients with brain metastases: The choice of treatment demands special attention]

The incidence and survival of patients with brain metastases is increasing which stresses the importance of treatment decisions regarding local control and toxicity. Unfortunately, the literature (that usually forms the backbone of treatment guidelines) encompasses mostly retrospective analysis of a wide variety of cancers and clinical presentations, and only limited data of the intracranial effects of novel systemic agents is available. The extrapolation of the literature to the individual patient should therefore be done with caution. For example, until more reliable prediction models are available, treatment guidelines should better avoid categorization of patients according to cut-off values (e.g. tumor size or number of metastases) to prevent suboptimal treatment decisions. For each patient the multidisciplinary team has to take all the individual factors that determine the prognosis into account and discuss the best options regarding symptomatology, local control and toxicity. This approach secures a tailored and optimised treatment strategy for every patient.

The role of alexithymia and empathy on radiation therapists' professional quality of life

BACKGROUND AND PURPOSE

Physical and mental well-being are crucial for oncology professionals as they affect performance at work. Personality traits, as alexithymia and empathy, may influence professional quality of life. Alexithymia involves diminished skills in emotion processing and awareness. Empathy is pertinent to the ability to understand another's 'state of mind/emotion'. The PROject on Burn-Out in RadiatioN Oncology (PRO BONO) investigates professional quality of life amongst radiation oncology professionals, exploring the role of alexithymia and empathy. The present study reports on data pertinent to radiation therapists (RTTs).

MATERIAL AND METHODS

An online survey targeted ESTRO members. Participants were asked to fill out 3 questionnaires for alexithymia, empathy and professional quality of life: (a) Toronto Alexithymia Scale (TAS-20); (b) Interpersonal Reactivity Index (IRI); (c) Professional Quality of Life Scale (ProQoL). The present analysis focuses on RTTS to evaluate compassion satisfaction (CS), secondary traumatic stress (STS) and Burnout and their correlation with alexithymia and empathy, using generalized linear modeling. Covariates found significant at univariate linear regression analysis were included in the multivariate linear regression model.

RESULTS

A total of 399 RTTs completed all questionnaires. The final model for the burnout scale of ProQoL found, as significal predictors, the TAS-20 total score (β = 0.46, p < 0 0.001), and the individual's perception of being valued by supervisor (β = -0.29, p < 0.001). With respect to CS, the final model included TAS-20 total score (β = -0.33, p < 0.001), the Empatic Concern domain (β = 0.23, p < 0.001) of the IRI questionnaire and the individual's perception of being valued by colleagues (β = 0.22, p < 0.001).

CONCLUSIONS

Alexithymia increased the likelyhood to experience burnout and negatively affected the professional quality of life amongst RTTs working in oncology. Empathy resulted in higher professional fulfillment together with collegaues' appreciation. These results may be used to benchmark preventing strategies and implement organization-direct and/or individual-directed interventions.

Abstract 92: Increasing TTFields treatment efficacy by targeting G2 cell cycle checkpoint

Introduction; Tumor Treating Fields (TTFields) is a novel non-invasive anticancer treatment modality utilizing alternating electric fields. TTFields is FDA approved for glioblastoma patients after demonstrating a 5 months increase in overall survival, and for unresectable mesothelioma patients after the STELLAR trial showed an overall survival of 18 months without increasing the toxicity. While the effectiveness of TTFields is initially attributed to the effects of TTFields during cell division, studies are ongoing analysing its interphase effects and impact on the tumor (micro)environment. Our aim is to further exploit the working mechanism of TTFields by analysing its effect on the cell cycle and identify targets to increase its efficacy.

Material and Methods; To analyse the effect of TTFields on the cell cycle, A172 glioblastoma cells were synchronized in S-phase by double thymidine block. Six hours post-release, cells were subjected to TTFields treatment (200kHz; 4,5V/cm). Cell cycle analysis was performed by flow cytometry (PI, α-phospho-histone H3Ser10). Efficacy of combination strategies were tested in 3 different glioblastoma cells lines (A172, U251 and SNB-19). Efficacy was quantified by colony formation assay (CFA) testing the cell reproductive death after treatment (i.e. only viable cells after treatment are replated to analyse the colony forming capacity).

Results: TTFields treatment of synchronized A172 cells showed that TTFields causes an accumulation of cells in G2 phase and delayed entry into mitosis with less than 1% of the cells in mitosis 4 hours after TTFields exposure (versus 5% of mitotic cells in the control arm, p&lt;0.001). This arrest can be abrogated by Wee1 inhibition (AZD1775) increasing the mitotic population to more than 35% at 4 hours after TTFields exposure (p&lt;0.001). To test the efficacy of targeting the G2 checkpoint during TTFields treatment, cells were treated with TTFields and a Wee1 (AZD1775, PD0166285) or Chk1 (AZD7762) inhibitor for 72 hours and then replated for CFA. We observed an impressive synergistic effect between TTFields and any of these G2 cell cycle interfering drugs in all three cell lines (p&lt;0.001).

Conclusion: The underlying mechanism of the G2 checkpoint activation and the synergistic effect of TTFields plus G2 checkpoint targeting agents is subject of ongoing research. By any means, the combination of TTFields and G2 checkpoint targeting agents causes a synergistic treatment effect and is a very promising strategy.

Citation Format: Paul Slangen, Mariska van Geldorp, Mark de Gooijer, Olaf van Tellingen, Gerben Borst. Increasing TTFields treatment efficacy by targeting G2 cell cycle checkpoint [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 92.

Professional quality of life and burnout amongst radiation oncologists: The impact of alexithymia and empathy

BACKGROUND AND PURPOSE

Different factors may influence the professional quality of life of oncology professionals. Among them, personality traits, as alexithymia and empathy, are underinvestigated. Alexithymia is about deficits in emotion processing and awareness. Empathy is the ability to understand another's 'state of mind'/emotion. The PROject on BurnOut in RadiatioN Oncology (PRO BONO) assesses professional quality of life, including burnout, in the field of radiation oncology and investigates alexithymia and empathy as contributing factors.

MATERIAL AND METHODS

An online survey was conducted amongst ESTRO members. Participants completed 3 validated questionnaires for alexithymia, empathy and professional quality of life: (a) Toronto Alexithymia Scale; (b) Interpersonal Reactivity Index; (c) Professional Quality of Life Scale. The present analysis, focusing on radiation/clinical oncologists, evaluates Compassion Satisfaction (CS), Secondary Traumatic Stress (STS) and Burnout and correlates them with alexithymia and empathy (empathic concern, perspective taking and personal distress) with generalized linear modeling. Significant covariates on univariate linear regression analysis were included in the multivariate linear regression model.

RESULTS

A total of 825 radiation oncologists completed all questionnaires. A higher level of alexithymia was associated to decreased CS (β: -0.101; SE: 0.018; p < 0.001), increased STS (β: 0.228; SE: 0.018; p < 0.001) and burnout (β: 0.177; SE: 0.016; p < 0.001). A higher empathic concern was significantly associated to increased CS (β: 0.1.287; SE: 0.305; p = 0.001), STS (β: 0.114; SE: 0.296; p < 0.001), with no effect on burnout. Personal distress was associated to decreased CS (β: -1.423; SE: 0.275; p < 0.001), increased STS (β: 1.871; SE: 0.283; p < 0.001) and burnout (β: 1.504; SE: 0.245; p < 0.001).

CONCLUSIONS

Alexithymic personality trait increased burnout risk, with less professional satisfaction. Empathic concern was associated to increased stress, without leading to burnout, resulting in higher professional fulfillment. These results may be used to benchmark preventing strategies, such as work-hour restrictions, peer support, debriefing sessions, and leadership initiatives for professionals at risk.

Evaluation of acute esophageal radiation-induced damage using magnetic resonance imaging: a feasibility study in mice

BACKGROUND

Thoracic and head and neck cancer radiation therapy (RT) can cause damage to nearby healthy organs such as the esophagus, causing acute radiation-induced esophageal damage (ARIED). A non-invasive method to detect and monitor ARIED can facilitate optimizing RT to avoid ARIED while improving local tumor control. Current clinical guidelines are limited to scoring the esophageal damage based on the symptoms of patients. Magnetic resonance imaging (MRI) is a non-invasive imaging modality that may potentially visualize radiation-induced organ damage. We investigated the feasibility of using T2-weighted MRI to detect and monitor ARIED using a two-phased study in mice.

METHODS

The first phase aimed to establish the optimal dose level at which ARIED is inducible and to determine the time points where ARIED is detectable. Twenty four mice received a single dose delivery of 20 and 40 Gy at proximal and distal spots of 10.0 mm (in diameter) on the esophagus. Mice underwent MRI and histopathology analysis with esophageal resection at two, three, and 4 weeks post-irradiation, or earlier in case mice had to be euthanized due to humane endpoints. In the second phase, 32 mice received a 40 Gy single dose and were studied at two, three, and 7 days post-irradiation. We detected ARIED as a change in signal intensity of the MRI images. We measured the width of the hyperintense area around the esophagus in all mice that underwent MRI prior to and after irradiation. We conducted a blind qualitative comparison between MRI findings and histopathology as the gold standard.

RESULTS/CONCLUSIONS

A dose of 40 Gy was needed to induce substantial ARIED. MRI detected ARIED as high signal intensity, visible from 2 days post-irradiation. Quantitative MRI analysis showed that the hyperintense area around the esophagus with severe ARIED was 1.41 mm wider than with no damage and MRI-only mice. The overall sensitivity and specificity were 56 and 43% respectively to detect any form of ARIED. However, in this study MRI correctly detected 100% of severe ARIED cases. Our two-phased preclinical study showed that MRI has the potential to detect ARIED as a change in signal intensity and width of enhancement around the esophagus.

Optical coherence tomography to detect acute esophageal radiation-induced damage in mice: A validation study

Radiation therapy for patients with non-small-cell lung cancer is hampered by acute radiation-induced toxicity in the esophagus. This study aims to validate that optical coherence tomography (OCT), a minimally invasive imaging technique with high resolution (~10 μm), is able to visualize and monitor acute radiation-induced esophageal damage (ARIED) in mice. We compare our findings with histopathology as the gold standard. Irradiated mice receive a single dose of 40 Gy at proximal and distal spots of the esophagus of 10.0 mm in diameter. We scan mice using OCT at two, three, and seven days post-irradiation. In OCT analysis, we define ARIED as a presence of distorted esophageal layering, change in backscattering signal properties, or change in the esophageal wall thickness. The average esophageal wall thickness is 0.53 mm larger on OCT when ARIED is present based on histopathology. The overall sensitivity and specificity of OCT to detect ARIED compared to histopathology are 94% and 47%, respectively. However, the overall sensitivity of OCT to assess ARIED is 100% seven days post-irradiation. We validate the capability of OCT to detect ARIED induced by high doses in mice. Nevertheless, clinical studies are required to assess the potential role of OCT to visualize ARIED in humans.

Predicting and implications of target volume changes of brain metastases during fractionated stereotactic radiosurgery

OBJECTIVE

To study the impact of target volume changes in brain metastases during fractionated stereotactic radiosurgery (fSRS) and identify patients that benefit from MRI guidance.

MATERIAL AND METHODS

For 15 patients (18 lesions) receiving fSRS only (fSRS_only) and 19 patients (20 lesions) receiving fSRS postoperatively (fSRS_postop), a treatment planning MRI (MR0) and repeated MRI during treatment (MR1) were acquired. The impact of target volume changes on the target coverage was analyzed by evaluating the planned dose distribution (based on MR0) on the planning target volume (PTV) during treatment as defined on MR1. The predictive value of target volume changes before treatment (using the diagnostic MRI (MRD)) was studied to identify patients that experienced the largest changes during treatment.

RESULTS

Target volume changes during fSRS did result in large declines of the PTV dose coverage up to -34.8% (median = 3.2%) for fSRS_only patients. For fSRS_postop the variation and declines were smaller (median PTV dose coverage change = -0.5% (-4.5% to 1.9%)). Target volumes changes did also impact the minimum dose in the PTV (fSRS_only; -2.7 Gy (-16.5 to 2.3 Gy), fSRS_postop; -0.4 Gy (-4.2 to 2.5 Gy)). Changes in target volume before treatment (i.e. seen between the MRD and MR0) predicted which patients experienced the largest dose coverage declines during treatment.

CONCLUSION

Target volume changes in brain metastases during fSRS can result in worsening of the target dose coverage. Patients benefiting the most from a repeated MRI during treatment could be identified before treatment.

Abstract 4419: Cell cycle analysis during TTF to exploit novel targets for increasing treatment efficacy

Cell cycle distribution and cell deathCell cycle distribution (index,%, t=12hrs)TreatmentControlTTFS10,5 ± 0.410.8 ± 0.5NSG229.9 ± 1.248.4 ± 0.9p&lt;0.05M6.3 ± 0.62.0 ± 0.2p&lt;0.05G153.0 ± 1.238.0 ± 0.8p&lt;0.05Cell death (%)TreatmentcontrolWee1TTFTTF+Wee1Cell count100+/-3.274.4 +/- 4.150.5 +/- 4.221.5 +/- 3.2SynergisticColony formation100 +/- 3.261.6 +/- 6.675.5 +/- 11.217.0 +/- 5.3Synergistic

While the effectiveness of TTFields is initially attributed to the effects of TTFields during cell division, recent studies have shown that TTFields additionally induce DNA damage and replication stress. We want to further exploit the working mechanism of TTFields, its effect on the cell cycle and identify targets to increase its efficacy.

A172 cells were synchronized in S-phase by double thymidine block. Six hours post-release (0h), cells were subjected to TTFields treatment (200kHz; 4,5V/cm pk-pk). Cell cycle analysis was performed by flow cytometry (PI, α-phospho-histone H3Ser10). Treatment of A172 cells synchronized in S phase with TTFields showed that TTFields cause an accumulation of cells in G2 phase, leading to delayed entry into mitosis and, subsequent lower entry into G1 (see table). Because this indication of G2 checkpoint activation we hypothesized the possible synergism between TTFields and Wee1 inhibition. A172 cells were simultaneously treated with TTFields (200kHz; 4,5V/cm pk-pk, 72hrs) and the Wee1 inhibitor (300nM, 72hrs). Cell survival was determined by automated cell counting (including Trypan Blue) and colony formation assay. We observed that abrogation of the G2 checkpoint by Wee1 inhibtion synergistically increases the efficacy of TTFields treatment (see table).

The underlying mechanism of the G2 checkpoint activation is subject of ongoing research. By any means, the combination of TTFields with the Wee1 inhibitor bypasses the G2 activation and causes a synergistic decrease in cell survival.

Citation Format: Paul Slangen, Mark de Gooijer, Olaf van Tellingen, Moshe Giladi, Gerben Borst. Cell cycle analysis during TTF to exploit novel targets for increasing treatment efficacy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4419.

Longitudinal stability of the folding pattern of the anterior cingulate cortex during development

Prenatal processes are likely critical for the differences in cognitive ability and disease risk that unfold in postnatal life. Prenatally established cortical folding patterns are increasingly studied as an adult proxy for earlier development events - under the as yet untested assumption that an individual's folding pattern is developmentally fixed. Here, we provide the first empirical test of this stability assumption using 263 longitudinally-acquired structural MRI brain scans from 75 typically developing individuals spanning ages 7 to 32 years. We focus on the anterior cingulate cortex (ACC) - an intensely studied cortical region that presents two qualitatively distinct and reliably classifiable sulcal patterns with links to postnatal behavior. We show - without exception-that individual ACC sulcal patterns are fixed from childhood to adulthood, at the same time that quantitative anatomical ACC metrics are undergoing profound developmental change. Our findings buttress use of folding typology as a postnatally-stable marker for linking variations in early brain development to later neurocognitive outcomes in ex utero life.

Mechanistic Insights into Molecular Targeting and Combined Modality Therapy for Aggressive, Localized Prostate Cancer

Radiation therapy (RT) is one of the mainstay treatments for prostate cancer (PCa). The potentially curative approaches can provide satisfactory results for many patients with non-metastatic PCa; however, a considerable number of individuals may present disease recurrence and die from the disease. Exploiting the rich molecular biology of PCa will provide insights into how the most resistant tumor cells can be eradicated to improve treatment outcomes. Important for this biology-driven individualized treatment is a robust selection procedure. The development of predictive biomarkers for RT efficacy is therefore of utmost importance for a clinically exploitable strategy to achieve tumor-specific radiosensitization. This review highlights the current status and possible opportunities in the modulation of four key processes to enhance radiation response in PCa by targeting the: (1) androgen signaling pathway; (2) hypoxic tumor cells and regions; (3) DNA damage response (DDR) pathway; and (4) abnormal extra-/intracell signaling pathways. In addition, we discuss how and which patients should be selected for biomarker-based clinical trials exploiting and validating these targeted treatment strategies with precision RT to improve cure rates in non-indolent, localized PCa.

When Stroop helps Piaget: An inter-task positive priming paradigm in 9-year-old children

To determine whether inhibitory control is domain general or domain specific in school children, we asked 40 9-year-old children to perform an inter-task priming paradigm in which they responded to Stroop items on the primes and to Piaget number conservation items on the probes. The children were more efficient in the inhibition of a misleading "length-equals-number" heuristic in the number conservation task if they had successfully inhibited a previous prepotent reading response in the Stroop task. This study provides evidence that the inhibitory control ability of school children generalizes to distinct cognitive domains, that is, verbal for the Stroop task and logico-mathematical for Piaget's number conservation task.

A phase I study on the combination of neoadjuvant radiotherapy plus pazopanib in patients with locally advanced soft tissue sarcoma of the extremities

Accumulating evidence suggests significant synergism combining radiotherapy (RT) with angiogenesis targeted therapies. This multicenter prospective phase I clinical trial established the safety profile and recommended dose for further studies of pazopanib concurrent with preoperative RT in patients with extremity soft tissue sarcomas (ESTS) in curative setting.

METHODS

Patients with deep seated intermediate and high grade sarcomas, ≥ 5 cm, received once daily pazopanib (dose-escalation cohorts 400 mg, 600 mg and 800 mg) for 6 weeks and 50 Gy preoperative RT starting Day 8. Surgery was performed 5-7 weeks later. Toxicity was scored according to CTC criteria 4.0. Dose limiting toxicities (DLT) were divided into two separate sets; DLT-I being toxicities occurring during the 6-week chemoradiotherapy period within the radiation portals until day of surgery (designated as DLT-I) and those occurring perioperatively until Day 21 after surgery (DLT-II).

RESULTS

A total of 12 patients were enrolled, 11 were evaluable (3 females and 8 males, median age 58 years, range 24-78 years, median tumor size 9 cm, range 5-15 cm). Ten underwent surgery. No increased toxicity inside the radiation fields was seen, but two of 10 patients (one each in the 400 mg and 600 mg cohorts) showed delayed wound healing after surgery. None of the patients showed significant volume reductions after RT. Evaluation of the resection specimen showed pathological (near) complete responses (≥ 95% necrosis rate) in four of 10 cases. Unexpectedly, grade 3 + hepatotoxicity led to premature pazopanib interruption in three of 11 (27%) of cases.

CONCLUSION

Apart from hepatotoxicity, neoadjuvant pazopanib 800 mg daily in combination with 50 Gy seems tolerable; the regimen appears to demonstrate promising activity in ESTS and is the recommended dose for further studies.

Folding of the anterior cingulate cortex partially explains inhibitory control during childhood: a longitudinal study

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Difficulties in cognitive control are related to several psychiatric conditions.

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Inhibitory control (IC) of children predicts academic and professional successes.

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ACC sulcal patterns at age 5 were related to IC efficiency at age 5 (Stroop scores).

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ACC sulcal patterns at age 5 explained IC efficiency at age 9 (Stroop scores).

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ACC sulcal patterns constrain IC efficiency during childhood.

Difficulties in cognitive control including inhibitory control (IC) are related to the pathophysiology of several psychiatric conditions. In healthy subjects, IC efficiency in childhood is a strong predictor of academic and professional successes later in life. The dorsal anterior cingulate cortex (ACC) is one of the core structures responsible for IC. Although quantitative structural characteristics of the ACC contribute to IC efficiency, the qualitative structural brain characteristics contributing to IC development are less-understood. Using anatomical magnetic resonance imaging, we investigated whether the ACC sulcal pattern at age 5, a stable qualitative characteristic of the brain determined in utero, explains IC at age 9. 18 children performed Stroop tasks at age 5 and age 9. Children with asymmetrical ACC sulcal patterns (n = 7) had better IC efficiency at age 5 and age 9 than children with symmetrical ACC sulcal patterns (n = 11). The ACC sulcal patterns appear to affect specifically IC efficiency given that the ACC sulcal patterns had no effect on verbal working memory. Our study provides the first evidence that the ACC sulcal pattern – a qualitative structural characteristic of the brain not affected by maturation and learning after birth – partially explains IC efficiency during childhood.

Optimising measles virus-guided radiovirotherapy with external beam radiotherapy and specific checkpoint kinase 1 inhibition

BACKGROUND AND PURPOSE

We previously reported a therapeutic strategy comprising replication-defective NIS-expressing adenovirus combined with radioiodide, external beam radiotherapy (EBRT) and DNA repair inhibition. We have now evaluated NIS-expressing oncolytic measles virus (MV-NIS) combined with NIS-guided radioiodide, EBRT and specific checkpoint kinase 1 (Chk1) inhibition in head and neck and colorectal models.

MATERIALS AND METHODS

Anti-proliferative/cytotoxic effects of individual agents and their combinations were measured by MTS, clonogenic and Western analysis. Viral gene expression was measured by radioisotope uptake and replication by one-step growth curves. Potential synergistic interactions were tested in vitro by Bliss independence analysis and in in vivo therapeutic studies.

RESULTS

EBRT and MV-NIS were synergistic in vitro. Furthermore, EBRT increased NIS expression in infected cells. SAR-020106 was synergistic with EBRT, but also with MV-NIS in HN5 cells. MV-NIS mediated (131)I-induced cytotoxicity in HN5 and HCT116 cells and, in the latter, this was enhanced by SAR-020106. In vivo studies confirmed that MV-NIS, EBRT and Chk1 inhibition were effective in HCT116 xenografts. The quadruplet regimen of MV-NIS, virally-directed (131)I, EBRT and SAR-020106 had significant anti-tumour activity in HCT116 xenografts.

CONCLUSION

This study strongly supports translational and clinical research on MV-NIS combined with radiation therapy and radiosensitising agents.