The Proteogenomics of Prostate Cancer Radioresistance.

Prostate cancer is frequently treated with radiotherapy. Unfortunately, aggressive radioresistant relapses can arise, and the molecular underpinnings of radioresistance are unknown. Modern clinical radiotherapy is evolving to deliver higher doses of radiation in fewer fractions (hypofractionation). We therefore analyzed genomic, transcriptomic, and proteomic data to characterize prostate cancer radioresistance in cells treated with both conventionally fractionated and hypofractionated radiotherapy. Independent of fractionation schedule, resistance to radiotherapy involved massive genomic instability and abrogation of DNA mismatch repair. Specific prostate cancer driver genes were modulated at the RNA and protein levels, with distinct protein subcellular responses to radiotherapy. Conventional fractionation led to a far more aggressive biomolecular response than hypofractionation. Testing preclinical candidates identified in cell lines, we revealed POLQ (DNA Polymerase Theta) as a radiosensitizer. POLQ-modulated radioresistance in model systems and was predictive of it in large patient cohorts. The molecular response to radiation is highly multimodal and sheds light on prostate cancer lethality. SIGNIFICANCE: Radiation is standard of care in prostate cancer. Yet, we have little understanding of its failure. We demonstrate a new paradigm that radioresistance is fractionation specific and identified POLQ as a radioresistance modulator.

A systematic review and meta-analysis on the prevalence of non-malignant, organic gastrointestinal disorders misdiagnosed as irritable bowel syndrome.

Treatable gastrointestinal disorders in patients with symptoms typical for irritable bowel syndrome (IBS) may be overlooked. The prevalence of five gastrointestinal conditions-bile acid diarrhoea (BAD), carbohydrate malabsorption (CM), microscopic colitis (MC), pancreatic exocrine insufficiency (PEI) and small intestinal bacterial overgrowth (SIBO) was systematically assessed from studies including consecutive patients meeting diagnostic criteria for IBS. 4 databases were searched from 1978 to 2020. Studies were included if they evaluated the prevalence of these conditions in secondary healthcare setting. Estimated pooled rates were calculated and statistical heterogeneity between studies was evaluated using Q and I2 statistics. Seven studies (n = 597) estimated the pooled prevalence for BAD as 41% (95% CI 29-54). 17 studies (n = 5068) estimated that of MC as 3% (95% CI 2-4%). Two studies (n = 478) suggested a rate of 4.6% (range: 1.8-6.1%) for PEI. Using breath testing, 26 studies (n = 6700) and 13 studies (n = 3415) estimated the prevalence of lactose and fructose malabsorption as 54% (95% CI 44-64%) and 43% (95% CI 23-62%); 36 studies (n = 4630) and 22 studies (n = 2149) estimated that of SIBO as 49% (95% CI 40-57%) with lactulose and 19% (95% CI 13-27%) with glucose. Rates of all conditions were significantly higher than in healthy controls. A significant proportion of patients presenting to secondary care with IBS have an organic condition which may account for their symptoms. Failure to exclude such conditions will deny patients effective treatment.

Improving the therapeutic ratio of radiotherapy against radioresistant cancers: Leveraging on novel artificial intelligence-based approaches for drug combination discovery.

Despite numerous advances in cancer radiotherapy, tumor radioresistance remain one of the major challenges limiting treatment efficacy of radiotherapy. Conventional strategies to overcome radioresistance involve understanding the underpinning molecular mechanisms, and subsequently using combinatorial treatment strategies involving radiation and targeted drug combinations against these radioresistant tumors. These strategies exploit and target the molecular fingerprint and vulnerability of the radioresistant clones to achieve improved efficacy in tumor eradication. However, conventional drug-screening approaches for the discovery of new drug combinations have been proven to be inefficient, limited and laborious. With the increasing availability of computational resources in recent years, novel approaches such as Quadratic Phenotypic Optimization Platform (QPOP), CURATE.AI and Drug Combination and Prediction and Testing (DCPT) platform have emerged to aid in drug combination discovery and the longitudinally optimized modulation of combination therapy dosing. These platforms could overcome the limitations of conventional screening approaches, thereby facilitating the discovery of more optimal drug combinations to improve the therapeutic ratio of combinatorial treatment. The use of better and more accurate models and methods with rapid turnover can thus facilitate a rapid translation in the clinic, hence, resulting in a better patient outcome. Here, we reviewed the clinical observations, molecular mechanisms and proposed treatment strategies for tumor radioresistance and discussed how novel approaches may be applied to enhance drug combination discovery, with the aim to further improve the therapeutic ratio and treatment efficacy of radiotherapy against radioresistant cancers.

Dosimetric uncertainties impact on cell survival curve with low energy proton.

There is an increasing number of radiobiological experiments being conducted with low energy protons (less than 5 MeV) for radiobiological studies due to availability of sub-millimetre focused beam. However, low energy proton has broad microdosimetric spectra which can introduce dosimetric uncertainty. In this work, we quantify the impact of this dosimetric uncertainties on the cell survival curve and how it affects the estimation of the alpha and beta parameters in the LQ formalism. Monte Carlo simulation is used to generate the microdosimetric spectra in a micrometer-sized water sphere under proton irradiation. This is modelled using radiobiological experiment set-up at the Centre of Ion Beam Application (CIBA) in National University of Singapore. Our results show that the microdosimetric spectra can introduce both systematic and random shifts in dose and cell survival; this effect is most pronounced with low energy protons. The alpha and beta uncertainties can be up to 10% and above 30%, respectively for low energy protons passing through thin cell target (about 10 microns). These uncertainties are non-negligible and show that care must be taken in using the cell survival curve and its derived parameters for radiobiological models.

High-Dimensional Characterization of the Systemic Immune Landscape Informs on Synergism Between Radiation Therapy and Immune Checkpoint Blockade.

PURPOSE: Improved antitumor responses have been observed in patients after combination radiation therapy (RT) and immune checkpoint blockade (ICB). Whether these clinical responses are linked to the host systemic immune system has not been elucidated. METHODS AND MATERIALS: In this single-institution prospective observational study, peripheral blood was longitudinally collected from 10 patients with metastatic disease who had responded to anti-PD-1/anti-PD-L1 ICB and received RT (8-50 Gy in 1-5 fractions) upon disease progression at the following timepoints: baseline (pre-RT), 1 to 2 weeks post-RT, and post-ICB (cycle 1) on reintroduction post-RT. To thoroughly characterize the interaction between combined RT-ICB and the host immune system, we performed high-dimensional, mass cytometry-based immunophenotyping of circulating lymphocytes using a 40-marker panel addressing lineage, differentiation, activation, trafficking, cytotoxicity, and costimulatory and inhibitory functions. Phenotypic expression of circulating lymphocytes was compared across patients and time points and correlated with post-RT tumor responses. RESULTS: Foremost, we demonstrated excellent posttreatment clinical responses, including 4 local responses with >50% reduction in radiated tumor size, 1 out-of-field response, and 4 patients who resumed ICB for >1 year. Baseline and post-RT immune states were highly heterogeneous among patients. Despite this interindividual heterogeneity in baseline immune states, we observed a systemic immune reaction to RT-ICB common across patients, histology, and radiation sites; a subset of pre-existing Ki-67+ CD8+ T cells were increased post-RT and further expanded upon reintroduction of ICB post-RT (2.3-fold increase, P = .02). Importantly, RT did not alter the phenotypic profile of these Ki-67+ CD8+ T cells, which was characterized by a distinct activated and differentiated effector phenotype. CONCLUSIONS: Collectively, these findings point toward a sustained reinvigoration of host antitumor immunity after RT-ICB and suggest an expansion in activated Ki-67+ CD8+ T cells as a possible demonstration of this synergy, thereby providing new insights that may support the development of optimal sequencing strategies.

Upconversion superballs for programmable photoactivation of therapeutics.

Upconversion nanoparticles (UCNPs) are the preferred choice for deep-tissue photoactivation, owing to their unique capability of converting deep tissue-penetrating near-infrared light to UV/visible light for photoactivation. Programmed photoactivation of multiple molecules is critical for controlling many biological processes. However, syntheses of such UCNPs require epitaxial growth of multiple shells on the core nanocrystals and are highly complex/time-consuming. To overcome this bottleneck, we have modularly assembled two distinct UCNPs which can individually be excited by 980/808 nm light, but not both. These orthogonal photoactivable UCNPs superballs are used for programmed photoactivation of multiple therapeutic processes for enhanced efficacy. These include sequential activation of endosomal escape through photochemical-internalization for enhanced cellular uptake, followed by photocontrolled gene knockdown of superoxide dismutase-1 to increase sensitivity to reactive oxygen species and finally, photodynamic therapy under these favorable conditions. Such programmed activation translated to significantly higher therapeutic efficacy in vitro and in vivo in comparison to conventional, non-programmed activation.

Vandetanib sensitizes head and neck squamous cell carcinoma to photodynamic therapy through modulation of EGFR-dependent DNA repair and the tumour microenvironment.

BACKGROUND: Epidermal growth factor receptor (EGFR) overexpression is characteristic in head and neck cancers and is associated with tumour regrowth following photodynamic therapy (PDT). PURPOSE: We investigated vandetanib, which selectively blocks EGFR and vascular endothelial growth factor receptor-2 (VEGFR-2), to enhance the efficacy of PDT. METHODS: We assessed the in vitro therapeutic efficacy of: 1) vandetanib; 2) PDT with the photosensitizer Chlorin e6 (Fotolon®); and 3) combined PDT + vadetanib treatment in CAL-27 oral squamous cell carcinoma (OSCC) cell line by cell viability, γH2AX foci immunostaining, cell cycle arrest and western blot. We also performed in vivo tumour regression study and immunohistochemical staining of formalin-fixed paraffin-embedded (FFPE) regressed and regrown tumour tissues. RESULTS: First, we observed significantly higher cytotoxicity and residual DNA damage in vandetanib + PDT-treated CAL-27 OSCC cells than tumour cells treated with PDT alone. This is due to impaired DNA DSB repair caused by downregulation of EGFR-mediated DNA-dependent protein kinase catalytic subunit (DNA-PKcs) activation. Next, combined vandetanib and PDT resulted in significant tumour growth delay in vivo that is linked to reduction of PDT-induced EGFR phosphorylation and cellular proliferation, along with loss of tumour vasculature. In particular, we observed significant revascularisation of the microenvironment that is associated with upregulated ERK1/2 phosphorylation in regrown tumours post-vandetanib + PDT, thereby corroborating the importance of microenvironmental modification for the observed drug-PDT synergistic interaction. CONCLUSION: Taken together, our data suggests that vandetanib enhances the efficacy of PDT through both direct and indirect effects on the cellular DNA repair machinery and tumour microenvironment, respectively.

Time to endoscopy for acute upper gastrointestinal bleeding: Results from a prospective multicentre trainee-led audit.

Background: Endoscopy within 24 h of admission (early endoscopy) is a quality standard in acute upper gastrointestinal bleeding (AUGIB). We aimed to audit time to endoscopy outcomes and identify factors affecting delayed endoscopy (>24 h of admission). Methods: This prospective multicentre audit enrolled patients admitted with AUGIB who underwent inpatient endoscopy between November and December 2017. Analyses were performed to identify factors associated with delayed endoscopy, and to compare patient outcomes, including length of stay and mortality rates, between early and delayed endoscopy groups. Results: Across 348 patients from 20 centres, the median time to endoscopy was 21.2 h (IQR 12.0-35.7), comprising median admission to referral and referral to endoscopy times of 8.1 h (IQR 3.7-18.1) and 6.7 h (IQR 3.0-23.1), respectively. Early endoscopy was achieved in 58.9%, although this varied by centre (range: 31.0-87.5%, p = 0.002). On multivariable analysis, lower Glasgow-Blatchford score, delayed referral, admissions between 7:00 and 19:00 hours or via the emergency department were independent predictors of delayed endoscopy. Early endoscopy was associated with reduced length of stay (median difference 1 d; p = 0.004), but not 30-d mortality (p = 0.344). Conclusions: The majority of centres did not meet national standards for time to endoscopy. Strategic initiatives involving acute care services may be necessary to improve this outcome.

What is the cost of delayed diagnosis of bile acid malabsorption and bile acid diarrhoea?

INTRODUCTION: 75Selenium taurocholic acid (SeHCAT) scanning diagnoses bile acid malabsorption/bile acid diarrhoea (BAM/BAD) and defines optimal treatment. Approximately 2% of the population have BAM/BAD. AIM: To evaluate the cost of delayed diagnosis of BAM/BAD. METHODS: Patients' notes who underwent SeHCAT scanning in three hospitals over a 1-year period were reviewed retrospectively. Scan results and treatment response were recorded. Package-of-care costs were calculated using costing tools from the National Institute for Health and Care Excellence and from United Lincolnshire Hospitals Trust business unit. RESULTS: Between June 2016 and May 2017, 19 men and 37 women (median age 58 (range 19-83)) of 3860 new patients seen in gastroenterology clinics were referred for SeHCAT scanning. Sixty-four per cent of scans were abnormal: 13 demonstrated severe (<5% 7-day SeHCAT retention), 13 moderate (5%-10%), 5 mild (10%-15%) and 5 borderline (15%-20%) BAD/BAM. Likely causes included primary BAD (n=16), cholecystectomy (n=13), inflammatory bowel disease (n=4) and other (n=3). If SeHCAT scanning was ordered at first consultation (n=11), patients reported 24 months (median) of symptoms (range 6-360) and the median diagnostic package-of-care cost was £811.40 (95% CI £625.59 to £1508.20). If SeHCAT scanning was booked later (n=25), patients reported symptoms for 30 months (median, range 0.5-360) and the cost was £1568.31 (95% CI £1200.55 to £1713.18). Following diagnosis, treatment led to symptom improvement (n=24), no change/deterioration (n=3) and not reported (n=9). CONCLUSIONS: SeHCAT is underused. Late diagnosis leads to unnecessary demands for other services and treatment delay. Early diagnosis achieves health benefits while reducing costs.

Concordance and incongruence in preclinical anxiety models: Systematic review and meta-analyses.

Rodent defense behavior assays have been widely used as preclinical models of anxiety to study possibly therapeutic anxiety-reducing interventions. However, some proposed anxiety-modulating factors - genes, drugs and stressors - have had discordant effects across different studies. To reconcile the effect sizes of purported anxiety factors, we conducted systematic review and meta-analyses of the literature on ten anxiety-linked interventions, as examined in the elevated plus maze, open field and light-dark box assays. Diazepam, 5-HT1A receptor gene knockout and overexpression, SERT gene knockout and overexpression, pain, restraint, social isolation, corticotropin-releasing hormone and Crhr1 were selected for review. Eight interventions had statistically significant effects on rodent anxiety, while Htr1a overexpression and Crh knockout did not. Evidence for publication bias was found in the diazepam, Htt knockout, and social isolation literatures. The Htr1a and Crhr1 results indicate a disconnect between preclinical science and clinical research. Furthermore, the meta-analytic data confirmed that genetic SERT anxiety effects were paradoxical in the context of the clinical use of SERT inhibitors to reduce anxiety.