Tumors Modulate the Systemic Vascular Response to Anti‐angiogenic Therapy

Toxicologic evaluation of new drug candidates routinely utilizes healthy animals. In oncology, there remains a limited understanding of the effects of novel test candidates in a diseased host. For vascular modulating agents (VMAs), an increased understanding of preclinical tumour–host interaction, and its potential to exacerbate or alleviate ‘off‐target’ effects of anti‐angiogenic administration, could aid in the prediction of adverse clinical outcomes in a defined cancer patient. We have previously reported that the implantation and growth of a range of human‐ and mouse‐derived tumours leads to structural vascular and, potentially, functional signalling changes within host mouse endocrine tissues, indicating possible roles for tumour‐ and host‐derived cytokines/growth factors and the liberation of myeloid‐derived suppressor cells in this phenomenon. Here, we further demonstrate that the growth of the Calu‐6 xenograft is associated with a resistance to VMA‐induced mouse peripheral endocrine vascular rarefaction (toxicity), with potential functional impact, notably with respect to mixed tyrosine kinase inhibition. The pathogenesis of these findings indicates a potential role for both tumour‐ and host‐derived basic fibroblast growth factor (bFGF), with associated upregulation in the intra‐tumoural autotaxin‐lysophosphatic acid signalling axis.

The growth of the Calu‐6 xenograft is associated with a resistance to vascular modulating agent‐induced mouse peripheral endocrine vascular rarefaction (toxicity), with potential functional impact, notably with respect to mixed tyrosine kinase inhibition. The pathogenesis of these findings indicates a potential role for basic fibroblast growth factor, with associated upregulation in the autotaxin‐lysophosphatic acid signalling axis.

Abstract 2778: Comparative multiplex digital phenotyping of the tumor microenvironment across multiple tumor types using a well characterized multi-tumor tissue microarray

The tumor microenvironment (TME) represents a complex interaction of immune and host cells and can be described broadly as ‘inflamed', ‘immune excluded' and ‘desert'; categories that may serve as predictive parameters for response to different immunotherapies. Multiplexed fluorescence and associated digital imaging platforms are important tools for defining the spatial components of the TME and can accelerate development of novel immunotherapy strategies. To investigate the TME across multiple tumor types simultaneously we have utilized a multi-tumor tissue microarray (TMA) covering 11 different tumor types comprising a total of 144 cases, each in duplicate with cores (1mm) taken from invasive margin (IM) and tumor center (TC). The TMA was stained using the UltiMapper I/O Immuno8 panel, which includes markers for CD3, CD4, CD8, FOXP3, CD68, PD-1, PD-L1, and a pan-CK/SOX10 cocktail as a tumor indicator. Stained TMAs were scanned on a fluorescence whole slide scanner (20X magnification) and marker images aligned using the UltiStacker software using the nuclear counterstain images as references from two rounds of imaging, to provide accurate marker colocalization data. Digital image analysis was performed using Visiopharm software to generate cell phenotype data, including localization to tumor and stroma, for each of the 288 cores. Comparative analysis of all tumor types regardless of core location (IM and TC combined) revealed gastric cancer, CRC, TNBC and NSCLC to be most highly infiltrated with CD3+ T cells, and ER+ and Her2+ breast cancers least infiltrated. The contribution of cytotoxic T cells (CD3+ CD8+) to the TME was greater for gastric cancer (approx. 50%) compared with NSCLC (approx. 20%) and the proportion of cytotoxic T cells activated/exhausted as defined by expression of PD-1 ranged from approx. 25% (eg. TNBC, CRC) to 1% (eg. ER+ BC). Spatial localization analyses of cytotoxic T cells revealed pancreatic and hepatic cancers as the most ‘excluded' as evidenced by low CD3+/CD8+ T cell numbers in tumor (CK+) compared with stromal regions (CK-). Interestingly, cytotoxic T cells with an exhausted phenotype (CD3+ CD8+ PD-1+) were preferentially infiltrated within CK+ tumor areas compared with stroma (CK-) for inflamed tumors such as gastric, TNBC and CRC. These data highlight the benefits of combining a fast, multiplexed staining protocol, with a detailed digital analysis of immune phenotypes spatially within well characterized tumor samples to better understand the TME (eg. inflamed, excluded) and identify tumor types more likely to benefit from different immunotherapeutic strategies.

Citation Format: Marie Cumberbatch, Douglas Wood, Christopher Womack, Milan Bhagat, Mael Manesse, Alison Bigley, Lorcan Sherry. Comparative multiplex digital phenotyping of the tumor microenvironment across multiple tumor types using a well characterized multi-tumor tissue microarray [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2778.

Tumors modulate fenestrated vascular beds and host endocrine status

Allograft and xenograft transplantation into a mouse host is frequently utilized to study cancer biology, tumor behavior, and response to treatment. Preclinical studies employing these models often focus solely upon the intra-tumoral effects of a given treatment, without consideration of systemic toxicity or tumor-host interaction, nor whether this latter relationship could modulate the toxicologic response to therapy. Here it is demonstrated that the implantation and growth of a range of human- and mouse-derived cell lines leads to structural vascular and, potentially, functional changes within peripheral endocrine tissues, a process that could conceivably ameliorate the severity of anti-angiogenic-induced fenestrated vessel attenuation. Observations suggest a multifactorial process, which may involve host- and tumor-derived cytokines/growth factors, and the liberation of myeloid-derived suppressor cells. Further investigation revealed a structurally comparable response to the administration of exogenous estrogen. These findings, in addition to providing insight into the development of clinical anti-angiogenic "adaptation," may be of significance within the "cancer-cachexia" and cancer-related anemia syndromes in man.

Abstract PO-001: Deep learning-based image analysis of the histological Glasgow Microenvironment Score in patients with colorectal cancer

Background: Efforts to prognostically stratify colorectal cancer (CRC) patients using histological samples has led to the development of the Glasgow Microenvironment Score (GMS). However, the subjective nature of the GMS assessment criteria makes reproducing the score challenging. Therefore, the aim of the current study was to assess the clinical utility of an image analysis-based approach. Methods: In two cohorts of patients (a test cohort of 297 Stage II/III CRC patients from Norway and a validation cohort of 233 Stage II/III CRC patients from Scotland), one H&E section representing the deepest point of tumour invasion was assessed for Tumour Stroma Percentage (TSP) and the Klintrup-Makinen (KM) local immune grade to produce the GMS. A decision forest-based classifier was built to segment the tumour and stroma compartments, having been trained on a hand annotated subset of the test cohort. A UNET convolutional neural network was trained on the same training set as the decision forest algorithm to segment and quantify the tumour and stroma components. Each section was also annotated for the invasive margin and a manually built, threshold-based lymphocyte detection algorithm applied to quantify the local immune grade. Results: The decision forest classifier was able to stratify the test cohort patients for cancer specific survival (P = 0.009) based on the patients TSP, however failed to stratify patients from the validation cohort (P = 0.055) for TSP without retraining, therefore the deep learning approach was used for this cohort. Individually, the TSP (P = 0.001) generated from the UNET based classifier and the quantification of the local immune grade (P = 0.005), both significantly stratified validation cohort patients for survival. When the individual scores were combined into a digital version of the GMS, not only did the image analysis approach significantly stratify patient survival (P < 0.0001), it also significantly correlated with the manual scores both statistically (Chi Square = 32, P = 1.5 × 10−8) and in terms of survival estimates per patient group (GMS 0 - manual = 159 months vs digital = 159 months; GMS 1 – manual = 136 months vs digital = 139 months ; GMS2 – manual 101 months vs 97 months). To negate the need for any annotation prior to analysis, the lymphocyte detection algorithm was applied to the stroma areas determined by the UNET algorithm. This fully automated digital version of the GMS was able to stratify validation cohort patients into the 3 prognostic groups based on CSS (P < 0.001), however, GMS 0 had a lower survival estimate (automated = 148 vs annotated = 159 months). Conclusion: An H&E based image analysis approach to the GMS, on a single H&E slide, holds prognostic significance for CRC patients and correlates significantly with manual pathological assessment, making the assessment of the GMS more time efficient, reproducible, and clinically relevant.

Citation Format: Christopher J. Bigley, John Waller, Alison Bigley, Karin Oien, Joanne Edwards, Antonia Roseweir. Deep learning-based image analysis of the histological Glasgow Microenvironment Score in patients with colorectal cancer [abstract]. In: Proceedings of the AACR Virtual Special Conference on Artificial Intelligence, Diagnosis, and Imaging; 2021 Jan 13-14. Philadelphia (PA): AACR; Clin Cancer Res 2021;27(5_Suppl):Abstract nr PO-001.

Automated image analysis of intra-tumoral and peripheral endocrine organ vascular bed regression using 'Fibrelength' as a novel structural biomarker

The study of vascular modulation has received a great deal of attention in recent years as knowledge has increased around the role of angiogenesis within disease contexts such as cancer. Despite rapidly expanding insights into the molecular processes involved and the concomitant generation of a number of anticancer vascular modulating chemotherapeutics, techniques used in the measurement of structural vascular change have advanced more modestly, particularly with regard to the preclinical quantification of off-target vascular regression within systemic, notably endocrine, blood vessels. Such changes translate into a number of major clinical side effects and there remains a need for improved preclinical screening and analysis. Here we present the generation of a novel structural biomarker, which can be incorporated into a number of contemporary image analysis platforms and used to compare tumour versus systemic host tissue vascularity. By contrasting the measurements obtained, the preclinical efficacy of vascular modulating chemotherapies can be evaluated in light of the predicted therapeutic window. Copyright © 2017 John Wiley & Sons, Ltd.

Inhibition of T-cell activation by the CTLA4-Fc Abatacept is sufficient to ameliorate proteinuric kidney disease

Diabetic nephropathy (DN) remains an unmet medical challenge as its prevalence is projected to continue to increase and specific medicines for treatment remain undeveloped. Activation of the immune system, in particular T-cells, is emerging as a possible mechanism underlying DN disease progression in humans and animal models. We hypothesized that inhibition of T-cell activation will ameliorate DN. Interaction of B7-1 (CD80) on the surface of antigen presenting cells with its binding partners, CTLA4 (CD152) and CD28 on T-cells, is essential for T-cell activation. In this study we used the soluble CTLA4-Fc fusion protein Abatacept to block cell surface B7-1, preventing the cellular interaction and inhibiting T-cell activation. When Abatacept was dosed in an animal model of diabetes-induced albuminuria, it reduced albuminuria in both prevention and intervention modes. The number of T-cells infiltrating the kidneys of DN animals correlated with the degree of albuminuria, and treatment with Abatacept reduced the number of renal T-cells. As B7-1 induction has been recently proposed to underlie podocyte damage in DN, Abatacept could be efficacious in DN by protecting podocytes. However, this does not appear to be the case as B7-1 was not expressed in 1) kidneys of DN animals; 2) stimulated human podocytes in culture; or 3) glomeruli of DN patients. We conclude that Abatacept ameliorates DN by blocking systemic T-cell activation and not by interacting with podocytes.

Statin-Induced Muscle Necrosis in the Rat: Distribution, Development, and Fibre Selectivity

Simvastatin and cerivastatin have been used to investigate the development of statin-induced muscle necrosis in the rat. This was similar for both statins and was treatment-duration dependent, only occurring after 10 days had elapsed even if the dose was increased, and still occurring after this time when dosing was terminated earlier as a result of morbidity. It was then widespread and affected all areas of the muscular system. However, even when myotoxicity was severe, particular individual muscles and some types of fibres within affected muscles were spared consistently. Fibre typing of spared muscles and of acutely necrotic fibres within affected muscles indicated a differential fibre sensitivity to statin-induced muscle necrosis. The fibres showed a necrotic response to statin administration that matched their oxidative/glycolytic metabolic nature: Least sensitive →I ↔ IIA ↔ IID ↔ IIB ← most sensitive. Type I and IIB fibres represent metabolic extremes of a continuum of metabolic properties through the fibre types with type I fibres most oxidative in metabolism and type IIB fibres most glycolytic. In addition, in some (nonnecrotic) glycolytic fibres from muscles showing early multifocal single fibre necrosis the only subcellular alterations present in isolation of any other changes were mitochondrial. These changes were characterised by an increased incidence of vacuolation and the formation of myelinoid vesicular bodies that accumulated in the subsarcolemmal areas. These findings suggest an important early involvement of mitochondria in selective glycolytic muscle fibre necrosis following inhibition of the enzyme HMG-CoA reductase.

Comparison of Computerized Image Analysis with Traditional Semiquantitative Scoring of Perls’ Prussian Blue Stained Hepatic Iron Deposition

Image analysis is now routinely employed as a tool in toxicologic pathology to help quantitate end points of efficacy and safety. It is regarded as a proficient and a sensitive technique to generate numerical data that can be easily interrogated for statistical evaluation. Traditional semiquantitative pathology scoring on the other hand is sometimes regarded as less accurate due to the limitations of the scoring systems employed and the day-to-day variations often noted between pathologists. We therefore decided to generate an optimized histochemical staining and image analysis protocol to compare the accuracy of semiquantitative scoring with computerized image analysis. In order to achieve this, we describe a standardized protocol for staining and image analysis that eliminates or minimizes as many sources of error as possible. The results of this experiment demonstrate that despite consistent variations in scoring between two independent pathologists, correlation with image analysis data of 0.91 to 0.95 (Spearman’s Rho test) was achieved. These data indicate that either image analysis or traditional semiquantitative scoring can generate accurate data. As a result of this, it appears that it is equally safe to employ either method dependent upon the complexity and the practicality of the task at hand provided that the experimental conditions are rigorously optimized and rigidly adhered to.

Evaluation of a convenient method of assessing rodent visual function in safety pharmacology studies: effects of sodium iodate on visual acuity and retinal morphology in albino and pigmented rats and mice

INTRODUCTION

We have evaluated the ability of a semi-automated, optomotor reflex method to assess drug-induced visual dysfunction, in albino and pigmented rats and mice.

METHODS

Male Han Wistar (HW) and Long Evans (LE) rats and mice (CD-1 and C57BL/6) were tested in a chamber formed by 4 computer monitors displaying a rotating vertical grating, to elicit head-tracking movements. The highest visible grating frequency was taken as the threshold of visual acuity, in cycles per degree (c/d). Animals received an intravenous infusion of either sodium iodate (50mg/kg) or 0.9% w/v NaCl (aq). They were tested 2h later, then re-tested daily for a further 3 days. The time course of the effect was assessed in HW rats over a 6-week period, including electron microscopy, and immunohistochemical analysis of markers of injury and repair in the retina.

RESULTS

Baseline visual acuities for HW and LE rats were 0.355 ± 0.007 and 0.530 ± 0.004 c/d, respectively, and 0.296 ± 0.003 c/d and 0.370 ± 0.001 c/d for CD-1 and C57BL/6 mice, respectively (n=10 for each). In HW rats there was a dramatic loss of visual acuity 2h after administration of sodium iodate (0.021 ± 0.021 c/d; P<0.001). Less dramatic decreases in visual acuity were seen in LE rats and in the two mouse strains. In HW rats, visual acuity was restored after 4 weeks. This paralleled the histopathological recovery of the peripheral retina, whereas the central retina did not recover.

DISCUSSION

The method proved to be very convenient, and the stability of visual acuity in vehicle control rats over a 6-week period also demonstrated its suitability for inclusion in long-term toxicity studies. Both albino and pigmented mice and rats are suitable for assessment of retinotoxicity using this method, but albino rats are the most sensitive to sodium iodate.

Rosuvastatin: characterization of induced myopathy in the rat

Rosuvastatin is a relatively new member of the statin family (HMG-CoA reductase inhibitors), with superior lipid-lowering effects and a pattern of clinical side effects, including a low incidence of myopathy, similar to other widely prescribed statins. This article describes investigations of myopathy in the rat following administration of very high doses of rosuvastatin. The nature of the changes were found to be entirely consistent with those seen with other statins, including a differential sensitivity of muscle fibers (with glycolytic fibers [type IIB] the most sensitive and oxidative fibers [type I] the least), a delay of approximately 10 days after the start of oral dosing before necrosis was apparent, and ultrastructural alterations appearing first in mitochondria. In addition, the development of myopathy was prevented by coadministration of mevalonate, the product of HMG-CoA reductase. The findings illustrate a pattern of induced myopathy in the rat directly attributable to inhibition of HMG-CoA reductase that is entirely consistent between the various statins, with the oral dose required to produce the changes being a differentiating feature (based on these new data and a previously reported study from the same laboratory): cerivastatin dose less than simvastatin, and simvastatin dose less than rosuvastatin.

AZD1152, a selective inhibitor of Aurora B kinase, inhibits human tumor xenograft growth by inducing apoptosis

PURPOSE

In the current study, we examined the in vivo effects of AZD1152, a novel and specific inhibitor of Aurora kinase activity (with selectivity for Aurora B).

EXPERIMENTAL DESIGN

The pharmacodynamic effects and efficacy of AZD1152 were determined in a panel of human tumor xenograft models. AZD1152 was dosed via several parenteral (s.c. osmotic mini-pump, i.p., and i.v.) routes.

RESULTS

AZD1152 potently inhibited the growth of human colon, lung, and hematologic tumor xenografts (mean tumor growth inhibition range, 55% to > or =100%; P < 0.05) in immunodeficient mice. Detailed pharmacodynamic analysis in colorectal SW620 tumor-bearing athymic rats treated i.v. with AZD1152 revealed a temporal sequence of phenotypic events in tumors: transient suppression of histone H3 phosphorylation followed by accumulation of 4N DNA in cells (2.4-fold higher compared with controls) and then an increased proportion of polyploid cells (>4N DNA, 2.3-fold higher compared with controls). Histologic analysis showed aberrant cell division that was concurrent with an increase in apoptosis in AZD1152-treated tumors. Bone marrow analyses revealed transient myelosuppression with the drug that was fully reversible following cessation of AZD1152 treatment.

CONCLUSIONS

These data suggest that selective targeting of Aurora B kinase may be a promising therapeutic approach for the treatment of a range of malignancies. In addition to the suppression of histone H3 phosphorylation, determination of tumor cell polyploidy and apoptosis may be useful biomarkers for this class of therapeutic agent. AZD1152 is currently in phase I trials.

A pilot evaluation of the use of tissue microarrays for quantitation of target distribution in drug discovery pathology

The use of tissue microarrays (TMAs) in the determination of novel target molecule distribution in organs is an expanding area of discovery pathology. This pilot study was carried out to assess the Chromavision automated cellular imaging system (ACIS) for quantitation of both mRNA and protein distribution in rat and dog TMAs. The targets chosen were a protein kinase, P-CIP2, for mRNA assessment and its downsteam target, peptidylglycine amidating monoxygenase (PAM), for immunohistochemistry (IHC). Oligonucleotide probes produced against P-CIP2, together with an antibody against PAM, were evaluated on rat and dog TMAs. A method for evaluation of target distribution using the ACIS was developed and involved a two-tier approach. Firstly, an initial scanning of the labelled slides identified which tissues expressed the target. Secondly, a more comprehensive analysis was made. This required operator interaction to select specific regions of interest within selected tissue cores and exclude any background labelling from the final assessment. This exacted the level of expression of P-CIP2 or PAM in different cellular populations in tissue cores. A comparative semi-quantitative analysis of the same arrays was concomitantly made by the pathologist in order to assess the relative benefits of a potentially time-consuming detailed morphological evaluation. This involved the histological identification by the pathologist of specific cell populations expressing P-CIP2 or PAM. In this study, we demonstrate the power of an image analysing system to provide quantitative data on target distribution by in situ hybridisation and IHC on normal TMAs. This methodology, together with detailed histological analysis by a pathologist, forms a guideline for future target distribution evaluation within discovery pathology.

Expression and replication timing patterns of wildtype and translocated BCL2 genes

Translocation of the BCL2 gene from chromosome 18 to chromosome 14 results in constitutive expression of the gene. We have recently demonstrated that the major breakpoint region (mbr) of BCL2, which is implicated in 70% of t(14;18) translocations present in human follicular lymphoma, is a matrix attachment region. Since these regions are implicated in control of both transcription and replication, we wished to determine whether BCL2 translocation was also accompanied by changes in replication timing of the translocated allele. Using both fluorescence in situ hybridization and allele-specific PCR, we have demonstrated that the translocated allele replicates at the G1/S boundary, while the wildtype allele continues to replicate as usual in mid-S phase. These differences are accompanied by allele-specific changes in BCL2 expression. Since the net structural effect of t(14;18) translocations within the mbr is to disrupt the BCL2 MAR and replace it with the IGH MARs located just downstream of each breakpoint, we conclude that MAR exchange is a significant, selectable outcome of these translocations. We propose that subsequent changes of replication and transcriptional patterns for the translocated BCL2 allele result from this exchange and represent important early steps in lymphomagenesis.