Abstract P6-04-03: Computational pathology based HER2 expression quantification in HER2-low breast cancer

Background HER2 directed therapies for breast cancer (BC) rely on accurate estimation of HER2 expression by pathologist scoring of immunohistochemically (IHC) stained tissue according to ASCO/CAP guidelines Emerging HER2-targeted antibody drug conjugates (ADCs) like trastuzumab deruxtecan (T-DXd), have demonstrated efficacy in the HER2-low (IHC 1+ or IHC 2+/ISH-) population (Modi, NEJM 2022). A deeper understanding of the spectrum of HER2 expression and its spatial distribution could provide insights about the mode of action of ADCs, including potential bystander activity. Computational pathology-based methods like Quantitative Continuous Scoring (QCS) can help here by objectively quantifying HER2 expression levels on a per cell basis from digitized HER2 IHC slides (Gustavson, SABCS 2020). We applied QCS to a cohort of HER2-negative (HER2-neg) patients (pts) from a retrospective study (NCT04807595) to quantify the prevalence of HER2 expression in this population and investigate the relationship with manual scoring. Methods To analyze the prevalence of HER2 expression in the HER2-neg population, we used available digital images (N=207 pts) from retrospectively rescored HER2 slides from tumors categorized as HER2-low or IHC 0 (IHC 0 or >0< 1+). QCS algorithm was applied to perform an instance segmentation of each tumor cell into the membrane, cytoplasmic and nuclear sub-compartments. HER2 expression levels on the membrane were estimated from a Hue-Saturation-Density model (Van der Laak, JQCS 2000) in terms of optical density (OD). Descriptive statistics and spatial modelling were used to aggregate cell-level information to a slide level score using the membrane OD values and tumor cell locations. A novel Spatial Proximity Score (SPS) was used to mathematically model the proportion of tumor cells that could potentially be targeted either directly or via bystander activity of ADCs. The analysis is ongoing, complete results with additional patient data to be presented. Analytical validation of the QCS algorithm demonstrated high correlation between OD values as measured on the automatically detected membranes from QCS and those measured on consolidated manual membrane annotations (N=2157 cells) from three pathologists (R = 0.993). This is very similar to the correlation observed between individual pathologists (R = 0.995). Results In the analyzed cohort (N=207), median OD of HER2-low tumors was significantly higher compared to IHC 0 tumors (one-sided Wilcoxon p-value < 0.001). A significant increase of OD values was observed for increasing IHC categories from 0 through >0 < 1+ and 1+ to 2+/ISH- (one-sided Jonckheere-Terpstra p-value < 0.001). OD values within each IHC category showed considerable variability, particularly in IHC 1+ and IHC 2+. In 49% of pts (N=101), greater than 88% of tumor cells expressed HER2 at any intensity (OD≥10). Among the remaining 106 pts, the number of potentially ADC-susceptible cells (within 25μm radius of HER2 expressing cells) as estimated by SPS was at least double the amount estimated by single cell-based scores alone in 45 cases (42%) and increased by at least 50% in another 12 cases (11%). Conclusions Computational approaches such as QCS can help us to objectively characterize the spectrum and spatial distribution of HER2 expression. These mathematical models contribute to our understanding of potential mechanisms of action of ADCs. While this study confirmed a general association of QCS-based scores with manual IHC categories, we also saw considerable variation, as some IHC 1+ or 2+ samples had low OD. Building on these and other promising initial results (Gustavson et al, SABCS 2020), we will further explore clinical relevance of QCS-based scoring. Eventually, digital scoring may be able to define data-driven signatures to select HER2-low pts that might benefit from HER2 targeted therapies.

Citation Format: Andreas Spitzmüller, Ansh Kapil, Anatoliy Shumilov, Jessica Chan, Lemonia Konstantinidou, Zonera Hassan, Mark Gustavson, Danielle Carroll, Della Varghese, Gareth D. James, Akira Moh, Andrew Livingston, Victoria de Giorgio-Miller. Computational pathology based HER2 expression quantification in HER2-low breast cancer [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P6-04-03.

Abstract P3-07-28: SERENA-1: Updated analyses from a Phase 1 study of the next generation oral selective estrogen receptor degrader camizestrant (AZD9833) combined with abemaciclib, in women with ER-positive, HER2-negative advanced breast cancer

Background: SERENA-1 (NCT03616587) is a Phase 1, multi-part, open-label study of camizestrant in women with ER+/HER2− advanced breast cancer. Parts A/B and C/D (escalation/expansion) examined camizestrant as monotherapy and in combination with palbociclib respectively and have been presented previously.1,2 Here we present data from parts G/H which examined camizestrant in combination with abemaciclib. Methods: The primary objective was to determine the safety and tolerability of camizestrant 75 mg once daily (QD) in combination with abemaciclib 150 mg twice daily (BID). Secondary objectives included investigation of anti-tumor response and pharmacokinetics (PK). Participants were previously treated women of any menopausal status (pre-menopausal women received this combination alongside ongoing ovarian function suppressors). Prior treatment with ≤2 lines of chemotherapy in the advanced setting was permitted. There was no limit on the number of lines of prior endocrine treatment in the advanced setting; previous treatment with CDK4/6 inhibitors (CDK4/6i) and fulvestrant was permitted. Results: As of 1st June 2022, 24 patients had received camizestrant in combination with abemaciclib with a median 7.7 month follow up. Tolerability of the combination of camizestrant and abemaciclib was consistent with that of each drug individually. No patient required camizestrant dose reduction. All camizestrant-related heart rate decreases were Grade 1 (asymptomatic). PK data for camizestrant in combination with abemaciclib were consistent with camizestrant as monotherapy and published abemaciclib steady-state PK data, indicating no clinically relevant drug-drug interaction. In these heavily pre-treated patients (46% prior chemotherapy, 75% prior CDK4/6i, 54% prior fulvestrant; all in the advanced disease setting) and of whom 67% had visceral metastases, the objective response rate was 5/19 (26.3%), the clinical benefit rate at 24 weeks was 16/24 (66.7%) and the median progression-free survival had not been reached, with 8/24 patients experiencing a progression event. These data support the use of camizestrant 75 mg QD combined with the approved abemaciclib dose. Conclusions: Camizestrant 75 mg QD in combination with abemaciclib 150 mg BID was well tolerated with encouraging clinical activity. The inclusion of this regimen in the ongoing Phase 3, SERENA-6 trial 3, of camizestrant combined with CDK4/6i versus an aromatase inhibitor, will further clarify the role of this combination in the treatment of patients with ER+/HER2− advanced breast cancer with tumors expressing ESR1 mutations. References 1. Baird R, Oliveira M, Ciruelos Gil EM, et al. SABCS 2020 Virtual Meeting. Abstract PS11-05. 2. Oliveira M, Hamilton EP, Incorvati J, et al. J Clin Oncol 40, 2022 (suppl 16; abstr 1032). 3. SERENA-6 trial. Available at https://clinicaltrials.gov/ct2/show/NCT04964934 We acknowledge Helen Heffron, PhD, from InterComm International who provided medical writing support funded by AstraZeneca.

Citation Format: Nicholas Turner, Christos Vaklavas, Emiliano Calvo, Javier Garcia-Corbacho, Jason Incorvati, Manuel Ruiz Borrego, Chris Twelves, Anne Armstrong, Begoña Bermejo, Erika Hamilton, Mafalda Oliveira, Eva Ciruelos, Peter Kabos, Manish R Patel, Maria Borrell, Howard Burris, Bruno de Paula, Alejandro Falcon, Cristina Hernando, Irene Moreno, Ciara S. O’Brien, Elena Shagisultanova, Ivan Victoria Ruiz, Judy S. Wang, Mei Wei, Tim Brier, Danielle Carroll, Carmela Ciardullo, Lisa Gibbons, itziar irurzun-Arana, Tony Jack, bistra kirova, Teresa Klinowska, Justin Lindemann, Julie Maidment, Alastair Mathewson, Rhiannon Maudsley, Robert McEwen, Christopher Morrow, Andy Sykes, Richard D. Baird. SERENA-1: Updated analyses from a Phase 1 study of the next generation oral selective estrogen receptor degrader camizestrant (AZD9833) combined with abemaciclib, in women with ER-positive, HER2-negative advanced breast cancer [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P3-07-28.

Abstract P3-07-13: The next generation oral selective estrogen receptor degrader (SERD) camizestrant (AZD9833) is active against wild type and mutant estrogen receptor α

Endocrine therapy forms the backbone treatment for patients with estrogen receptor (ER) positive tumors in both the adjuvant and metastatic setting. Aromatase inhibitors (AI) are the most common endocrine treatment option. Mutation of ESR1, the gene encoding ERα, is a common mechanism of resistance to AIs which leads to ligand independent activity of ERα. Camizestrant (AZD9833) is a next generation SERD and pure ER antagonist that is in Phase 3 trials (SERENA-4: NCT04711252; SERENA-6: NCT04964934). Here we report the preclinical and clinical activity of camizestrant in patients with ESR1 wild-type (ESR1wt) and mutant (ESR1m) tumors. The binding affinities of camizestrant, fulvestrant, and estradiol to wt ERα and ERα variants with mutations in the ligand binding domain were assessed. All three compounds exhibited reduced binding to mutant forms of ERα compared with wt ERα; the Y537S mutation had the greatest impact on binding. This was reflected in requirement for greater concentrations of camizestrant and fulvestrant to degrade and antagonize mutated ERα and to impact cellular proliferation in MCF-7 cells that expressed Y537S ESR1m compared to ESR1wt MCF-7 cells. Furthermore, while a 3 mg/kg dose of camizestrant achieved a maximal anti-tumor effect in a ESR1wt patient derived xenograft model, a 10 mg/kg was required for maximal effect in a D538G ESR1m model. Considering this difference between ESR1m and ESR1wt, pharmacokinetic/pharmacodynamic modelling of preclinical data predicted that a camizestrant dose of 75 mg would be maximally efficacious in patients with ESR1m tumors. Indeed, analysis of ESR1m circulating tumor DNA levels in patients from the SERENA-1 (NCT03616587) Phase 1 trial showed a clear effect of 14 days treatment with 75 mg camizestrant resulting in a >2-fold reduction in ESR1m variant allele frequency in 12/13 (92%) cases with complete clearance of ESR1m ctDNA in 7/13 (54%) cases. Interestingly, the clinical activity of camizestrant was higher in heavily pretreated patients with metastatic breast cancer with ESR1m tumors compared to those with no detectable mutation (ESR1m not detected). At a camizestrant dose of 75 mg, median progression-free survival was 8.3 months (maturity 12/15) in patients with ESR1m tumors compared to 5.6 months (8/9) in those with ESR1m not detected (data cut-off 6 October 2021). Camizestrant-induced ERα degradation was seen in both groups (mean reduction in H-score 42% in ESR1m tumors (n= 12 evaluable pairs) and 46% in tumors with ESR1m not detected (n=7)). Whole transcriptome analysis revealed a trend towards higher ERα activity at baseline in ESR1m tumors compared to ESR1m not detected; ERα activity reduced on treatment in both groups. Consistent with the clinical activity data, camizestrant induced more profound reductions in cell proliferation in ESR1m tumors compared to ESR1m not detected tumors (as seen by greater reductions in Ki67-positive tumor cells). These data demonstrate the activity of camizestrant in patients with ESR1m tumors. Clinical activity along with degradation and antagonism of the ERα is also seen in patients with tumors in which ESR1 mutations are not detected. In this heavily pre-treated Phase 1 patient population from SERENA-1, ESR1m may be a predictive biomarker to enrich for patients with maintained endocrine sensitivity. The SERENA-6 trial is investigating the efficacy and safety of camizestrant plus a CDK4/6 inhibitor in patients with metastatic breast cancer and detectable ESR1m. We acknowledge Helen Heffron, PhD, from InterComm International who provided medical writing support funded by AstraZeneca.

Citation Format: Christopher Morrow, Larissa Carnevalli, Richard D. Baird, Tim Brier, Carmela Ciardullo, Natalie Cureton, Mandy Lawson, Robert McEwen, Myria Nikolaou, Anne Armstrong, Begoña Bermejo, Emiliano Calvo, Eva Ciruelos, Javier Garcia-Corbacho, Erika Hamilton, Jason Incorvati, Peter Kabos, Mafalda Oliveira, Manish R Patel, Manuel Ruiz-Borregó, Nicholas Turner, Chris Twelves, Christos Vaklavas, Danielle Carroll, Steven Ching, Nevena Cvetesic, Michelle DuPont, Lisa Gibbons, Alastair Mathewson, Rhiannon Maudsley, Pablo Morentin Gutierrez, Avinash Reddy, Jaime Rodriguez-Canales, Susana Ros, Dhivya Sudhan, Andy Sykes, David Whitson, Teresa Klinowska, Justin Lindemann. The next generation oral selective estrogen receptor degrader (SERD) camizestrant (AZD9833) is active against wild type and mutant estrogen receptor α [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P3-07-13.

Abstract P6-04-16: ART: Automated Region segmentation of Tumor on HER2-stained breast cancer tissue

Background Computational pathology-based methods, eg, Quantitative Continuous Scoring (QCS) [Gustavson, SABCS 2020], are built to provide objective and quantitative methods to assess HER2 expression in breast cancer (BC). For accurate HER2 quantification, it is important to exclude non-invasive epithelium from analysis since HER2 overexpression could be more frequent in ductal carcinoma in situ (DCIS) and pleomorphic lobular carcinoma in situ (PLCIS) than in invasive BC [Lari, J Cancer 2011]. Generally, computational pathology-based approaches require experts to delineate the invasive BC regions of interest for analysis and exclude all benign/non-invasive epithelium. Developing a tool that delineates the invasive BC regions automatically without human intervention to avoid subjectivity of manual annotation by pathologists is ideal. We developed a novel, deep-learning–based system, called DualScaleNet, to perform Automated Region segmentation of Tumor (ART) by automatically identifying the invasive BC regions and excluding benign/non-invasive epithelium on HER2-stained digitized images. Identification and diagnosis of these regions, especially the in situ tumors are a challenge as they can mimic benign and invasive lesions causing wrong HER2 evaluation. Additional stains (eg, p63 for myoepithelial cells or laminin for basement membrane) are often required for diagnosis [Pinder, Mod Pathol 2010] but were not available for this study. Methods DualScaleNet works simultaneously on HER2-stained immunohistochemistry (IHC) image patches at 2 different resolutions. The target branch uses a higher resolution RGB image (0.5 μm/pixel) to learn accurate local details; the context branch uses a lower resolution image (4.0 μm/pixel) to incorporate more context in visual learning. The algorithm generates 4 output image layers representing probabilities of 4 classes: invasive tumor, ductal/lobular carcinoma in situ, benign epithelium, and other tissue. The final segmentation result is generated by assigning each image pixel the class with the largest probability value. The algorithm was trained using ground truth (GT) annotations generated by 5 pathologists using 6157 square field of views (FOVs), 200-500 μm in size. These FOVs were collected from 850 whole slide images (WSI), spanning 9 commercial BC sample cohorts stained with different HER2 assays and scanned by several versions of the Aperio AT2 scanner. The samples included a mixture of biopsies and resections and covered different BC histologies and HER2 staining intensities. To evaluate the reproducibility of tumor area detection by human pathologists, an interpathologist comparison in detection of invasive tumor regions was performed using 225 FOVs annotated by multiple pathologists. Results Analysis generated an average Dice/F1 Score of 81.6% among different pathologists for invasive cancer. On the same sample set (independent of the ART training set), the invasive cancer detection by the ART algorithm was on par with human pathologists, achieving a similar average Dice/F1 score of 80.7%. Conclusions Novel deep learning-based ART algorithm provides accurate segmentation of invasive cancer on HER2-stained IHC images. The performance was verified against the GT annotations provided by multiple pathologists. Since the algorithm is trained using annotations from multiple pathologists, it is not possible to generate higher accuracy with computational pathology than is achievable between independent pathologists. Importantly, the same WSI read by the ART will consistently output the exact same tumor region identification result thus removing the inherent human subjectivity and variability, while improving the turnaround time for analysis. This development serves as the necessary foundation upon which a computational pathology-based diagnostic can be built.

Citation Format: Ansh Kapil, Anatoliy Shumilov, Philipp Wortmann, Sihem Khelifa, Jessica Chan, Michel Vandenberghe, Craig Barker, Mark Gustavson, Danielle Carroll, Hadassah Sade, Günter Schmidt. ART: Automated Region segmentation of Tumor on HER2-stained breast cancer tissue [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P6-04-16.

Abstract P2-09-03: Quantification of HER2 expression and spatial biology using computational pathology: A cross-assay validation study in breast cancer

Background Conventional pathologic scoring of HER2 by IHC is proven to distinguish potential responders to trastuzumab but has not been effective for next generation antibody drug conjugates (ADCs) such as trastuzumab deruxtecan (T-DXd), which is capable of bystander killing. Several alternative approaches have been deployed to measure HER2, including immunofluorescence and mRNA sequencing. We have developed a novel and fully automated computational pathology technique, Quantitative Continuous Scoring (QCS), to quantify the level and distribution of HER2 from digitized HER2 IHC slides in an objective, quantifiable, and reproducible manner on a per-cell basis [Gustavson et al., SABCS 2020]. To further validate this approach, we performed a systematic multi-omic comparison of QCS to orthogonal methods of HER2 quantitation on a cohort of primary and metastatic breast cancer cases (N=30). Methods HER2 was evaluated using three independent methods on serial tissue sections obtained from 30 archival FFPE breast cancer samples distributed over the full range of HER2 expression, from 0 to 3+. HER2-IHC staining (clone 4B5, Roche Tissue Diagnostics) was performed using standard methods and cases were scored by two pathologists using CAP/ASCO guidelines and H-scores were assigned. We performed FISH (HER2 IQFISH pharmDx [Dako]; PathVysion HER-2 DNA Probe Kit [Vysis]), mRNA quantification of ERBB2 transcript levels (Nano String), and immunofluorescence (IF; HER2 clone 29D8, CST). Imaged with Vectra (Akoya) and analyzed with Halo (Indica). QCS readouts were generated from the above-mentioned digital images of IHC slides by using a fully automated image analysis pipeline; readouts included per-cell staining intensity measurements of membranes and cytoplasmic sub-compartments in terms of optical density (OD) [Van der Laak, JQCS 2000], which were aggregated to a single slide-level score. Additionally, using the OD measurements and the cell locations, a Spatial Proximity Score (SPS) was computed, summing the percentage of cells with OD≥10 (corresponding to the limit of visual detection of IHC staining) as well as the percentage of cells with OD< 10 within a prespecified radius (25µm) of a neighboring cell with OD≥10. Results Our analysis demonstrated that QCS-based scoring correlates with orthogonal measurements used in this study. Comparing protein-based assays, the observed Pearson correlation was R=0.88 between QCS median membrane OD and IHC H-scores, R=0.86 with IF-based HER2 mean cell expression intensity, and R=0.85 with IF-based H-scores. Correlation with transcriptomic profiling was R=0.81 for OD vs. mRNA, however ERBB2 transcript levels did not distinguish between HER2 0, 1+, and 2+ FISH negative cases, while QCS was able to do so. Correlation between protein-based and nucleic-acid based assays were numerically worse, with R=0.64 for OD vs. FISH. All samples (including those with HER2 IHC scores of 0 and H-Scores < 10) had at least ~20% of cells with quantifiable HER2 expression by OD, the presence of which was confirmed using IF. For cases in the lowest quartile of HER2 expression by OD, SPS identified 20-50% additional HER2-null cells that were in close proximity to HER2-expressing cells that may be vulnerable to bystander killing. Conclusion QCS-based scoring is consistent with orthogonal protein-based measurements across the range of HER2 expression. Most importantly, QCS derived-spatial analysis features identify additional patients in the lower end of HER2 expression that might be highly relevant for ADC response prediction, particularly if a drug exerts bystander activity. Further clinical verification and validation on large cohorts is needed. Footnote: This study was approved by the IRB at MSKCC.

Citation Format: Joshua Drago, Zonera Hassan, Jan Zaucha, Ansh Kapil, Fatemeh Derakhshan, Fresia Pareja, Shimulov Anatoliy, Fanni Ratzon, Travis J Hollman, Claire Myers, Jessica Chan, Andrea Spitzmuller, Mark Gustavson, Danielle Carroll, Dara Ross, Jorge Reis-Filho, Carl barrett, Sihem Khalifa, Schmidt Guenter, Hadassah Sade, Sarat Chandarlapaty. Quantification of HER2 expression and spatial biology using computational pathology: A cross-assay validation study in breast cancer [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P2-09-03.

The HORIZON III retrospective exploratory analysis: HER2 expression amplification in colorectal cancer

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Background: Although regularly used in breast and gastric cancer, HER2 testing is not routinely performed in colorectal cancer (CRC). Immunohistochemistry (IHC) and in situ hybridization (ISH) scoring have not been optimized for assessment of HER2 overexpression and amplification in CRC. Varying rates of HER2 overexpression (2%-11%) have been reported in previously untreated CRC (Wang World J Gastrointest Oncol 2019) and patients with advanced/metastatic CRC with HER2 amplification or overexpression respond poorly to current standard of care therapies (Sartore-Bianchi Oncologist 2019). We characterized HER2 prevalence in a retrospective cohort analysis of clinical trial patients. Methods: The HORIZON III trial (NCT00384176) evaluated FOLFOX + bevacizumab or cediranib (AZD2171) as first-line (1L) treatment in patients with metastatic CRC (Schmoll J Clin Oncol 2012). The primary objective of this analysis of a subset of HORIZON III samples was to characterize HER2 prevalence in 1L metastatic CRC. Secondary and exploratory objectives included correlating HER2 status to other molecular findings (eg, RAS/RAF mutations), clinicopathologic characteristics, and patient outcomes. IHC was performed using a monoclonal anti-HER2 antibody PATHWAY HER2 [4B5] Ventana on primary CRC tumor sections and scored according to ASCO/CAP guidelines for gastric cancer (Bartley Arch Pathol Lab Med 2016). H&E staining was performed to determine the adequacy of tumor samples (ie, > 100 viable tumor cells per specimen). All tumors with an IHC score of 2+ were analyzed for amplification by ISH (HER2 IQFISH pharmDx dual probe kit, Agilent Technologies K573111-5). Targeted mutation panel testing was used to determine other molecular alterations. Descriptive statistics were used to summarize baseline and clinical outcome data by HER2 status. The current analysis was approved by the AstraZeneca bioethics review board. Results: Of the 1614 patients in HORIZON III, 396 met the inclusion criteria of appropriate consent, sufficient tumor sample for analysis, and a unique identifier. HER2-positive tumors (IHC3+ or IHC2+/ISH+) were identified in 2.1% of samples; 1.3% were IHC3+ and 0.8% were IHC2+/ISH+. Compared with IHC3+, IHC2+ tumors were more heterogeneous with mixed components of cells weakly expressing HER2 and lacking HER2 expression. Conclusions: This exploratory analysis of the HORIZON III study provides insights into HER2 prevalence in 1L, unselected, advanced/metastatic CRC, finding that 2.1% of tumors were HER2 positive. The demographic characteristics of patients with analyzable samples were representative of the entire HORIZON III study population; however, further assessment of KRAS status and other clinicopathological characteristics is needed. These data may inform future clinical development and support selection of patients with CRC who are likely to benefit from HER2 targeting therapies. Clinical trial information: NCT00384176 .

Selumetinib Plus Adjuvant Radioactive Iodine in Patients With High-Risk Differentiated Thyroid Cancer: A Phase III, Randomized, Placebo-Controlled Trial (ASTRA)

PURPOSE

Selumetinib can increase radioactive iodine (RAI) avidity in RAI-refractory tumors. We investigated whether selumetinib plus adjuvant RAI improves complete remission (CR) rates in patients with differentiated thyroid cancer (DTC) at high risk of primary treatment failure versus RAI alone.

METHODS

ASTRA (ClinicalTrials.gov identifier: NCT01843062) is an international, phase III, randomized, placebo-controlled, double-blind trial. Patients with DTC at high risk of primary treatment failure (primary tumor > 4 cm; gross extrathyroidal extension outside the thyroid gland [T4 disease]; or N1a/N1b disease with ≥ 1 metastatic lymph node(s) ≥ 1 cm or ≥ 5 lymph nodes [any size]) were randomly assigned 2:1 to selumetinib 75 mg orally twice daily or placebo for approximately 5 weeks (no stratification). On treatment days 29-31, recombinant human thyroid-stimulating hormone (0.9 mg)-stimulated RAI (131I; 100 mCi/3.7 GBq) was administered, followed by 5 days of selumetinib/placebo. The primary end point (CR rate 18 months after RAI) was assessed in the intention-to-treat population.

RESULTS

Four hundred patients were enrolled (August 27, 2013-March 23, 2016) and 233 randomly assigned (selumetinib, n = 155 [67%]; placebo, n = 78 [33%]). No statistically significant difference in CR rate 18 months after RAI was observed (selumetinib n = 62 [40%]; placebo n = 30 [38%]; odds ratio 1.07 [95% CI, 0.61 to 1.87]; P = .8205). Treatment-related grade ≥ 3 adverse events were reported in 25/154 patients (16%) with selumetinib and none with placebo. The most common adverse event with selumetinib was dermatitis acneiform (n = 11 [7%]). No treatment-related deaths were reported.

CONCLUSION

Postoperative pathologic risk stratification identified patients with DTC at high risk of primary treatment failure, although the addition of selumetinib to adjuvant RAI failed to improve the CR rate for these patients. Future strategies should focus on tumor genotype-tailored drug selection and maintaining drug dosing to optimize RAI efficacy.

Serial monitoring of genomic alterations in circulating tumor cells of ER-positive/HER2-negative advanced breast cancer: feasibility of precision oncology biomarker detection

Nearly all estrogen receptor (ER)-positive (POS) metastatic breast cancers become refractory to endocrine (ET) and other therapies, leading to lethal disease presumably due to evolving genomic alterations. Timely monitoring of the molecular events associated with response/progression by serial tissue biopsies is logistically difficult. Use of liquid biopsies, including circulating tumor cells (CTC) and circulating tumor DNA (ctDNA), might provide highly informative, yet easily obtainable, evidence for better precision oncology care. Although ctDNA profiling has been well investigated, the CTC precision oncology genomic landscape and the advantages it may offer over ctDNA in ER-POS breast cancer remain largely unexplored. Whole-blood (WB) specimens were collected at serial time points from patients with advanced ER-POS/HER2-negative (NEG) advanced breast cancer in a phase I trial of AZD9496, an oral selective ER degrader (SERD) ET. Individual CTC were isolated from WB using tandem CellSearch® /DEPArray™ technologies and genomically profiled by targeted single-cell DNA next-generation sequencing (scNGS). High-quality CTC (n = 123) from 12 patients profiled by scNGS showed 100% concordance with ctDNA detection of driver estrogen receptor α (ESR1) mutations. We developed a novel CTC-based framework for precision medicine actionability reporting (MI-CTCseq) that incorporates novel features, such as clonal predominance and zygosity of targetable alterations, both unambiguously identifiable in CTC compared to ctDNA. Thus, we nominated opportunities for targeted therapies in 73% of patients, directed at alterations in phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha (PIK3CA), fibroblast growth factor receptor 2 (FGFR2), and KIT proto-oncogene, receptor tyrosine kinase (KIT). Intrapatient, inter-CTC genomic heterogeneity was observed, at times between time points, in subclonal alterations. Our analysis suggests that serial monitoring of the CTC genome is feasible and should enable real-time tracking of tumor evolution during progression, permitting more combination precision medicine interventions.

Concomitant KRAS mutations attenuate sensitivity of non-small cell lung cancer cells to KRAS G12C inhibition

The development of covalent inhibitors against KRAS G12C represents a major milestone in treatment of RAS-driven cancers, especially in non-small cell lung cancer (NSCLC), where KRAS G12C is one of the most common oncogenic driver. Here we investigated if additional KRAS mutations co-occur with KRAS G12C (c.34G>T) in NSCLC tumours and if such mutation co-occurrence affects cellular response to G12C-specific inhibitors. Analysis of a large cohort of NSCLC patients whose tumours harboured KRAS mutations revealed co-occurring KRAS mutations in up to 8% of tumours with the KRAS c.34G>T mutation. KRAS c.35G>T was the most frequently co-occurring mutation, and could occur on the same allele (in cis) translating to a single mutant KRAS G12F protein, or on the other allele (in trans), translating to separate G12C and G12V mutant proteins. Introducing KRAS c.35G>T in trans in the KRAS G12C lung cancer model NCI-H358, as well as the co-occurrence in cis in the KRAS G12F lung cancer model NCI-H2291 led to cellular resistance to the G12C-specific inhibitor AZ’8037 due to continuing active MAPK and PI3K cascades in the presence of the inhibitor. Overall, our study provides a comprehensive assessment of co-occurring KRAS mutations in NSCLC and in vitro evidence of the negative impact of co-occurring KRAS mutations on cellular response to G12C inhibitors, highlighting the need for a comprehensive KRAS tumour genotyping for optimal patient selection for treatment with a KRAS G12C inhibitor.

Abstract P2-13-23: Activity and tolerability of combination of trastuzumab deruxtecan with the pan-AKT inhibitor capivasertib in preclinical HER2+ and HER2-low breast cancer models

Background: Trastuzumab deruxtecan (T-DXd) is an antibody-drug conjugate composed of an anti-HER2 antibody, a cleavable tetrapeptide-based linker, and a cytotoxic topoisomerase I inhibitor approved for HER2+ metastatic breast and gastric cancer. Clinically, T-DXd has demonstrated significant antitumor activity in both HER2+ and HER2-low (IHC 1+ & 2+/ISH-) breast cancer patients. The PI3K/AKT pathway is frequently activated in breast cancer, and mediates signals downstream of HER2. T-DXd has been shown to inhibit downstream AKT signaling driven by HER2. Capivasertib, a potent, selective inhibitor of all three AKT isoforms (AKT1/2/3) has shown clinical activity in breast cancer trials. Given the clinical activity of both agents, the anti-tumor activity of combined treatment with T-DXd with capivasertib, was explored preclinically in HER2+ and HER2-low models. Methods: The antiproliferative activity of the combination of T-DXd with capivasertib was assessed in a panel of 27 breast cancer cell lines using a 7 day viability assay. To determine whether the combination also translates in vivo, T-DXd (3 and 10mg/kg Q3W) and capivasertib (130mg/kg BID 4 days on/3 days off) were tested in KPL4 (HER2+). To determine whether the combination of T-DXd and capivasertib has a negative impact on normal tissue integrity, we further evaluated the combination in a human 2D in vitro bone marrow progenitor assay. Results: The combination treatment was more effective than each single agent in 6/27 of the models tested in vitro, resulting in increased cell kill in the viability assay. Two of these positive cell lines, HCC1569 (HER2+) and AU565 (HER2+) were PTEN altered, KPL4 (HER2+) and EFM19 (ER+) were mutant in PIK3CA, and HCC1419 (HER2+) and ZR-75-30 (ER+/HER2+) were neither PTEN or PIK3CA altered. In KPL4 xenografts, the combination of T-DXd and capivasertib showed modest increased activity over monotherapy T-DXd or capivasertib at 28d (Tumor Growth Inhibition (TGI) of T-DXd = 76%, capivasertib = 25%, and T-DXd+Capivasertib = 83%; p=0.3 combo vs. mono T-DXd) and more markedly at 46d (TGI of the combination vs T-DXd monotherapy was 65%). Importantly, the combination showed enhanced durability of response (stasis) in 100% mice while 38% (3/8) mice in the T-DXd mono therapy treatment group were actively re-growing at 46d. In the in vitro bone marrow assay, the combination demonstrated no increased interaction over monotherapy activity (average Loewe Synergy Score of -0.2). Conclusions: These results suggest combining T-DXd with capivasertib has potential to be active in breast cancer patients, with activity likely to be enriched in tumours with mutations in PIK3CA and PTEN, but also in tumours with no PI3K pathway activating mutations.

Citation Format: Azadeh Cheraghchi Bashi, Theresa Proia, Suzanne Randle, Mark Anderton, Zeshaan Rasheed, J. Elizabeth Pease, Simon Barry, Danielle Carroll, Jerome Mettetal. Activity and tolerability of combination of trastuzumab deruxtecan with the pan-AKT inhibitor capivasertib in preclinical HER2+ and HER2-low breast cancer models [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P2-13-23.

Recombinant Newcastle Disease Virus Immunotherapy Drives Oncolytic Effects and Durable Systemic Antitumor Immunity

A recombinant Newcastle Disease Virus (NDV), encoding either a human (NDVhuGM-CSF, MEDI5395) or murine (NDVmuGM-CSF) GM-CSF transgene, combined broad oncolytic activity with the ability to significantly modulate genes related to immune functionality in human tumor cells. Replication in murine tumor lines was significantly diminished relative to human tumor cells. Nonetheless, intratumoral injection of NDVmuGM-CSF conferred antitumor effects in three syngeneic models in vivo; with efficacy further augmented by concomitant treatment with anti-PD-1/PD-L1 or T-cell agonists. Ex vivo immune profiling, including T-cell receptor sequencing, revealed profound immune-contexture changes consistent with priming and potentiation of adaptive immunity and tumor microenvironment (TME) reprogramming toward an immune-permissive state. CRISPR modifications rendered CT26 tumors significantly more permissive to NDV replication, and in this setting, NDVmuGM-CSF confers immune-mediated effects in the noninjected tumor in vivo Taken together, the data support the thesis that MEDI5395 primes and augments cell-mediated antitumor immunity and has significant utility as a combination partner with other immunomodulatory cancer treatments.

Abstract 3143: Monitoring circulating tumor cell (CTC) and circulating tumor DNA (ctDNA) genomic alterations in ER positive (POS)/HER2 negative (NEG) advanced breast cancer during endocrine therapy: correlative study of AZD9496 oral SERD phase I trial

Purpose: The vast majority of advanced ER POS breast cancers eventually cease responding to endocrine (ET) and other therapies leading to evolution of lethal disease. However, timely monitoring of the molecular events associated with response/progression in tissue biopsies is logistically difficult. The use of liquid biopsies, such as CTC and ctDNA, in this context has been of recent interest.

Patients and Methods: Individual CTC and ctDNA were obtained at different time points from patients with advanced ER POS/HER2 NEG breast cancer enrolled in a Phase I trial of AZD9496, an oral selective estrogen receptor degrader (SERD) ET. The CTC, purified using tandem CellSearch®/DepArray™ technologies, were genomically profiled by DNA single cell next generation sequencing (scNGS). Plasma ctDNA was isolated from blood collected in Streck BCT tubes. Genomic profiling was performed by targeted gene panel scNGS for CTC and ddPCR for ERα gene (ESR1) mutations in ctDNA.

Results: 123 high-quality CTCs from 12 patients profiled by scNGS showed 100% concordance with ctDNA in detection of driver ESR1 somatic mutations. CTC scNGS additionally revealed extensive intra-patient heterogeneity of driver alterations, that would have been unresolvable by bulk ctDNA profiling, including separate subclonal CTC populations emerging within the same patient. ScNGS revealed potential opportunities for targeted therapies in 73% of patients, directed at alterations in PIK3CA, FGFR2, KIT and BRAF, at times present as 2 or more targets in the same or different cell populations. In one patient, an emergent, distinct, BRAF p.V600E targetable alteration was detected in a subpopulation of CTCs collected at the progression time point but not at baseline.

Conclusion: Serial monitoring of CTC and ctDNA genomic alterations is feasible and should enable real-time tracking of response/progression, tumor evolution and opportunities for precision medicine interventions.

Citation Format: Andi K. Cani, Emily M. Dolce, Elizabeth P. Darga, Kevin Hu, Martha Brown, Chia-Jen Liu, Jackie Pierce, Kieran Bradbury, Kimberly Aung, Gaia Schiavon, Danielle Carroll, T. H. Carr, Teresa Klinowska, Justin Lindemann, Gayle Marshall, Vicky Rowlands, Elizabeth A. Harrington, J. Barrett, Anne Armstrong, Richard Baird, Erika Hamilton, Seock-Ah Im, Komal Jhaveri, Manish R. Patel, Caroline Dive, Scott A. Tomlins, Aaron M. Udager, Daniel F. Hayes, Costanza Paoletti. Monitoring circulating tumor cell (CTC) and circulating tumor DNA (ctDNA) genomic alterations in ER positive (POS)/HER2 negative (NEG) advanced breast cancer during endocrine therapy: correlative study of AZD9496 oral SERD phase I trial [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 3143.

An adaptive, biomarker-directed platform study of durvalumab in combination with targeted therapies in advanced urothelial cancer

Durvalumab is a programmed death-ligand 1 (PD-L1) inhibitor with clinical activity in advanced urothelial cancer (AUC)¹. AUC is characterized by several recurrent targetable genomic alterations^2-5. This study ( NCT02546661 , BISCAY) combined durvalumab with relevant targeted therapies in biomarker-selected chemotherapy-refractory AUC populations including: (1) fibroblast growth factor receptor (FGFR) inhibitors in tumors with FGFR DNA alterations (FGFRm); (2) pharmacological inhibitor of the enzyme poly-ADP ribose polymerase (PARP) in tumors with and without DNA homologous recombination repair deficiency (HRRm); and (3) TORC1/2 inhibitors in tumors with DNA alteration to the mTOR/PI3K pathway^3-5.This trial adopted a new, biomarker-driven, multiarm adaptive design. Safety, efficacy and relevant biomarkers were evaluated. Overall, 391 patients were screened of whom 135 were allocated to one of six study arms. Response rates (RRs) ranged 9-36% across the study arms, which did not meet efficacy criteria for further development. Overall survival (OS) and progression-free survival (PFS) were similar in the combination arms and durvalumab monotherapy arm. Biomarker analysis showed a correlation between circulating plasma-based DNA (ctDNA) and tissue for FGFRm. Sequential circulating tumor DNA analysis showed that changes to FGFRm correlated with clinical outcome. Our data support the clinical activity of FGFR inhibition and durvalumab monotherapy but do not show increased activity for any of the combinations. These findings question the targeted/immune therapy approach in AUC.

Macrophage Activation Status Rather than Repolarization Is Associated with Enhanced Checkpoint Activity in Combination with PI3Kγ Inhibition

Suppressive myeloid cells mediate resistance to immune checkpoint blockade. PI3Kγ inhibition can target suppressive macrophages, and enhance efficacy of immune checkpoint inhibitors. However, how PI3Kγ inhibitors function in different tumor microenvironments (TME) to activate specific immune cells is underexplored. The effect of the novel PI3Kγ inhibitor AZD3458 was assessed in preclinical models. AZD3458 enhanced antitumor activity of immune checkpoint inhibitors in 4T1, CT26, and MC38 syngeneic models, increasing CD8⁺ T-cell activation status. Immune and TME biomarker analysis of MC38 tumors revealed that AZD3458 monotherapy or combination treatment did not repolarize the phenotype of tumor-associated macrophage cells but induced gene signatures associated with LPS and type II INF activation. The activation biomarkers were present across tumor macrophages that appear phenotypically heterogenous. AZD3458 alone or in combination with PD-1-blocking antibodies promoted an increase in antigen-presenting (MHCII⁺) and cytotoxic (iNOS⁺)-activated macrophages, as well as dendritic cell activation. AZD3458 reduced IL-10 secretion and signaling in primary human macrophages and murine tumor-associated macrophages, but did not strongly regulate IL-12 as observed in other studies. Therefore, rather than polarizing tumor macrophages, PI3Kγ inhibition with AZD3458 promotes a cytotoxic switch of macrophages into antigen-presenting activated macrophages, resulting in CD8 T-cell-mediated antitumor activity with immune checkpoint inhibitors associated with tumor and peripheral immune activation.

Abstract OT-09-02: A randomized, open-label, parallel-group, multicenter phase 2 study comparing the efficacy and safety of oral AZD9833 versus fulvestrant in women with advanced ER-positive HER2-negative breast cancer (SERENA-2)

Background AZD9833 is a next-generation oral selective estrogen receptor (ER) antagonist and degrader (SERD) that has shown anti-tumor efficacy in a range of pre-clinical xenograft models of breast cancer. The first-in-human study, assessing AZD9833 as a monotherapy and in combination with palbociclib (SERENA-1; NCT03616587), established a dose-dependent safety profile with clinical benefit and target engagement in pre- and post-menopausal women at all dose levels. Here, we describe the design of SERENA-2, a Phase 2 randomized, open-label trial of three different doses of AZD9833 versus fulvestrant. Methods SERENA-2 is a global comparative study of three different doses of AZD9833 versus fulvestrant in post-menopausal women with advanced ER+, HER2− breast cancer with disease recurrence or progression after ≥1 endocrine therapy. The study will evaluate the efficacy and safety of AZD9833 monotherapy once daily at three dose levels, versus fulvestrant monotherapy administered according to its label. Eligible patients will have received no prior fulvestrant or other oral SERD, and no more than one endocrine therapy and one chemotherapy in the advanced setting. Prior treatment with CDK4/6 inhibitors is permitted. Patients will be randomized 1:1:1:1 to one of four treatment groups: AZD9833 75 mg, 150 mg, 300 mg, or fulvestrant. The primary objective of the study is to determine the clinical efficacy of AZD9833 as assessed by progression-free survival, compared with fulvestrant. Secondary objectives include objective response rate, duration of response, percentage change in tumor size at 16 weeks, clinical benefit rate at 24 weeks, and overall survival. Pharmacokinetics, pharmacodynamic biomarker changes from baseline, and effects of AZD9833 and fulvestrant on patients’ health-related quality of life will also be assessed. Exploratory endpoints include predictive markers of response and/or acquired resistance to AZD9833 and fulvestrant, including circulating tumor DNA mutation profiling and dynamics, circulating tumor cell enumeration, and analysis of tumor samples. Patient enrollment commenced in Q2 2020, with a target enrollment of 288 patients across approximately 100 sites in up to 17 countries. Efficacy analyses will compare each dose of AZD9833 with fulvestrant. Sample size was calculated to provide 80% power for the primary endpoint. The primary analysis will use a Cox proportional hazards model stratified by prior use of CDK4/6 inhibitors and presence of lung and/or liver metastases to compare progression-free survival in each dose of AZD9833 versus fulvestrant. Another randomized, open-label, parallel-group, pre-surgical study investigating the biological effects of AZD9833 in ER+, HER2− primary breast cancer (SERENA-3) is also ongoing. For more information please contact Dr Mafalda Oliveira at: moliveira@vhio.net.

Citation Format: Mafalda Oliveira, Maxine Bennett, Ali Khalil, Richard Mather, Rhiannon Maudsley, Sam McGuinness, Christopher J Morrow, Andy Sykes, Li Zhang, Teresa Klinowska, Justin PO Lindemann, Danielle Carroll. A randomized, open-label, parallel-group, multicenter phase 2 study comparing the efficacy and safety of oral AZD9833 versus fulvestrant in women with advanced ER-positive HER2-negative breast cancer (SERENA-2) [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 OT-09-02.

Abstract 5544: Newcastle Disease Virus in human derived tumors: Understanding immune recruitment and activation via virally delivered IL-12

Oncolytic viruses (OV) are defined by their intrinsic or engineered tropism for tumor cells. Understanding the drivers of susceptibility to infection as well as the downstream intracellular signaling and immune activation profile is critical in identifying the patients that will respond to OV therapy. Newcastle Disease Virus (NDV) is a negative stranded RNA avian paramyxovirus, here modified to encode human GM-CSF or IL-12. Patient derived xenografts (PDX) can more accurately reflect the genetic, epigenetic, and architectural heterogeneity of human tumors and were therefore selected to model the in vivo activity of NDV:GM-CSF. Eighty-nine independent models derived from patients with Bladder, Colorectal, Head and Neck, Kidney, Liver, Lung, Ovarian, Pancreatic, and Breast tumors were studied. Mice were dosed intravenously with NDV:GM-CSF, monitored for pharmacodynamic and pharmacokinetic changes 48 hours after the first dose, and followed for tumor growth inhibition. Objective response was observed in 68% of treated mice, with responses observed in all indications. Using total stranded RNAseq, we were able to assess changes in human tumor, murine immune infiltrate, and viral RNA. Results showed that NDV:GM-CSF treatment leads to increases in transcripts of inflammatory chemokines and cytokines such as RANTES and CXCL9, with induction directly correlated to level of viral replication. Additionally, we saw increases in NKp46 and IL-12R, markers of NK cells. To assess if IL-12 would augment immune activation, we treated surgically resected human tumors with NDV:IL-12. NDV:IL-12 was capable of infecting tumor cells, generating IL-12 protein, and driving a strong IFNγ response. Here we show that NDV can infect a wide variety of human tumors across multiple indications and drive a potent immune activation which can be modulated by transgenes. This data provides insight into what types of tumors could be treated with NDV:GM-CSF or NDV:IL-12.

Citation Format: Nicholas M. Durham, Kelly McGlinchey, Shannon Burke, Todd Creasy, Nicola Rath, Noel Monks, Ravinder Tammali, Kevin Schifferli, Nick Holoweckyj, Susie Hayes, Emma Jones, Elizabeth J. Kelly, Danielle Carroll, James Harper, Katie Streicher. Newcastle Disease Virus in human derived tumors: Understanding immune recruitment and activation via virally delivered IL-12 [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 5544.

A phase I dose escalation and expansion study of the next generation oral SERD AZD9833 in women with ER-positive, HER2-negative advanced breast cancer

1024

Background: AZD9833 is an oral selective estrogen receptor (ER) antagonist and degrader (SERD) that has shown antitumor efficacy in a range of preclinical models of breast cancer. Methods: SERENA-1 (NCT03616587) is an ongoing Phase 1, open-label study in pre- and post-menopausal women, after ≥1 endocrine therapy and ≤2 prior chemotherapies for ER+ HER2- advanced breast cancer (ABC). The primary objective is to determine the safety and tolerability of AZD9833 once daily (QD), with dose-limiting toxicities (DLTs) in 28d defining the maximum tolerated dose. Secondary objectives include pharmacokinetics and anti-tumor response. Pharmacodynamic (PD) analysis includes ER modulation in paired tumor biopsies and ctDNA dynamic changes. Results: At 20 January 2020: 60 patients were treated (median prior therapies 5 (1–9); prior fulvestrant (Fv) 82%; prior CDK4/6i 68%) across five doses; 25 mg QD n=12, 75 mg QD n=12, 150 mg QD n=13, 300 mg QD n=13, 450 mg QD n=10. AZD9833 exposure was dose proportional after multiple doses, with a median terminal t1/2 of 12h. Treatment-related AEs experienced by ≥10% of patients were visual disturbances (53%; 91% G1, 6% G2, 3% G3), bradycardia/sinus bradycardia (45%; 93% G1, 7% G2), nausea (18%; 46% G1, 55% G2), fatigue (13%; 38% G1, 63% G2), dizziness (10%; 83% G1, 17% G3) vomiting (10%; 50% G1, 33% G2, 17% G3), and asthenia (10%; 67% G1, 33% G2). Three patients experienced DLTs: G3 QTcF prolongation (300 mg); G3 vomiting (450 mg); and a combination of G2 visual disturbance, G2 headache and G2 gait disturbance (450 mg). DLTs resolved with dose reduction. No G4 or 5 AEs were reported. Efficacy data are presented in the table below; objective response rate (ORR) and clinical benefit rate (CBR) at 24 weeks. Clinical trial information: NCT03616587 . ER signalling pathway modulation was observed in all dose cohorts. In patients where clinical responses occurred and paired biopsies obtained, 98% reduction in Ki67 was measured. Updated data will be presented. Conclusions: AZD9833 has an encouraging efficacy and dose-dependent safety profile. Evidence of clinical benefit and target engagement was observed at all dose levels in women with ER+ ABC, including patients pre-treated with CDK4/6i and Fv, and those with ESR1 mutations. A Phase 2 study comparing efficacy and safety of three doses AZD9833 vs Fv is planned (NCT04214288). [Table: see text]

A Randomized, Open-label, Presurgical, Window-of-Opportunity Study Comparing the Pharmacodynamic Effects of the Novel Oral SERD AZD9496 with Fulvestrant in Patients with Newly Diagnosed ER+ HER2- Primary Breast Cancer

PURPOSE

Fulvestrant, the first-in-class selective estrogen receptor (ER) degrader (SERD), is clinically effective in patients with ER⁺ breast cancer, but it has administration and pharmacokinetic limitations. Pharmacodynamic data suggest complete ER degradation is not achieved at fulvestrant's clinically feasible dose. This presurgical study (NCT03236974) compared the pharmacodynamic effects of fulvestrant with AZD9496, a novel, orally bioavailable, nonsteroidal, potent SERD, in treatment-naïve patients with ER⁺ HER2^- primary breast cancer awaiting curative intent surgery.

PATIENTS AND METHODS

Patients were randomized 1:1 to receive AZD9496 250 mg twice daily from day 1 for 5-14 days, or fulvestrant 500 mg on day 1. On-treatment imaging-guided core tumor biopsies were taken between day 5 and 14 and compared with pretreatment diagnostic biopsies. The primary objective was to compare the effects of AZD9496 and fulvestrant on ER expression. Secondary objectives included changes in progesterone receptor (PR) and Ki-67 pharmacokinetic/pharmacodynamic relationships and safety.

RESULTS

Forty-six women received treatment (AZD9496 n = 22; fulvestrant n = 24); 35 paired biopsies were evaluable (AZD9496 n = 15; fulvestrant n = 20). The least square mean estimate for ER H-score reduction was 24% after AZD9496 versus 36% after fulvestrant treatment (P = 0.86). AZD9496 also reduced PR H-scores (-33.3%) and Ki-67 levels (-39.9%) from baseline, but was also not superior to fulvestrant (PR: -68.7%, P = 0.97; Ki-67: -75.4%, P = 0.98). No new safety findings were identified.

CONCLUSIONS

This was the first presurgical study to demonstrate that an oral SERD affects its key biological targets. However, AZD9496 was not superior to fulvestrant at the dose tested.

Abstract P6-04-01: A pre-surgical, window of opportunity study comparing the novel oral SERD AZD9496 with fulvestrant in patients with newly diagnosed ER+ HER2- primary breast cancer

Background: Estrogen receptor positive (ER+) breast cancer is routinely treated with endocrine therapies targeting the ER axis. However, primary and secondary resistance ultimately limits the use of these agents. Fulvestrant (FULV) is the first-in-class selective ER degrader (SERD) clinically effective in patients with ER+ breast cancer, both naïve and resistant to tamoxifen and aromatase inhibitors. FULV has low oral bioavailability, and its dose-dependent pharmacodynamic (PD) activity and clinical efficacy is limited by the currently approved maximal feasible dose (MFD) of 500 mg, which is administered monthly as two intramuscular injections. AZD9496 is an orally bioavailable, nonsteroidal, selective and potent degrader and antagonist of ER in preclinical models. This pre-surgical, window of opportunity study (NCT03236974) compared PD changes and the PD/pharmacokinetic (PK) relationships of AZD9496 with FULV in patients with newly diagnosed ER+ HER2- breast cancer awaiting curative intent surgery.Methods: In this open-label, multicenter study, patients were randomized 1:1 to receive oral AZD9496 250 mg BID from Day 1 for 5-14 days or FULV 500 mg administered intramuscularly on Day 1 only. On-treatment image-guided core tumor biopsies were taken between Days 5 and 14. The primary objective was to compare the effects of AZD9496 and FULV on ER expression in tumor tissue using pre-dose biopsies as baseline. Secondary objectives were changes in progesterone receptor (PR) and Ki-67 biomarkers, AZD9496 and FULV plasma concentrations during treatment, and safety. Immunohistochemistry was used to determine ER and PR H-scores, and Ki-67 index, and treatment effects were compared using an analysis of covariance model. Blood samples for PK analysis were taken at on-treatment biopsy and 1-2 hours afterwards. Adverse events (AEs) were monitored from screening through to a follow-up visit 28 days after the last study dose.Results: Of the 49 women enrolled, 46 received treatment (AZD9496 n=22; FULV n=24) and of these, 35 paired biopsies were evaluable (AZD9496 n=15; FULV n=20). The least square mean estimate for the reduction in ER H-score after AZD9496 treatment was 24% (80% CI: 34.4, 14.3), and after FULV treatment was 36% (44.9, 27.7), with a least square mean difference between AZD9496 and FULV of 12% (p=0.86). AZD9496 was not superior to FULV in terms of ER modulation at the tested dose. AZD9496 also reduced PR H-scores and Ki-67 levels from baseline (by 33.3% and 39.9%, respectively). These effects were not statistically superior to FULV at the tested dose (PR: -68.7%, p=0.97; Ki 67: 75.4%, p=0.98).Plasma exposure of AZD9496 (AUC -40%, Cmax -25%) was lower than predicted based on PK data from the previous phase 1 study, whereas FULV exposure was consistent with historical data. No clear exposure-response relationship for plasma concentration at biopsy and PD markers for AZD9496 or FULV were observed.The median treatment duration of AZD9496 was 9.5 days (range: 6-15), and the relative dose intensity was 100% (range: 90-125); no patients discontinued AZD9496. AZD9496 and FULV were both well tolerated, and no new safety findings were identified. No grade ≥3 toxicities or serious AEs occurred. Conclusion: AZD9496 250 mg BID reduced ER, PR and Ki-67 expression, and as such, is the first pre surgical study to demonstrate an oral SERD impacting its key biological targets. These reductions were not superior to the FULV clinically approved dose, which performed as expected based on historical data. Pre-surgical studies represent an important method to test the proof of mechanism of novel SERDs early in clinical development.

Citation Format: John FR Robertson, Abigail Evans, Stephan Henschen, Cliona Kirwan, Ali Jahan, Laura Kenny, J. Michael Dixon, Peter Schmid, Ashutosh Kothari, Omar Mohamed, Peter A Fasching, Kwok-Leung Cheung, Rachel Wuerstlein, Danielle Carroll, Teresa Klinowska, Justin PO Lindemann, Alexander MacDonald, Richard Mather, Rhiannon Maudsley, Michele Moschetta, Myria Nikolaou, Martine P Roudier, Tinnu Sarvotham, Gaia Schiavon, Diansong Zhou, Li Zhou, Nadia Harbeck. A pre-surgical, window of opportunity study comparing the novel oral SERD AZD9496 with fulvestrant in patients with newly diagnosed ER+ HER2- primary breast cancer [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P6-04-01.

Abstract 1456: MEDI5395: A recombinant oncolytic virus with oncolytic and immune modulatory properties

MEDI5395 is a genetically modified attenuated Newcastle disease virus (NDV). A reverse genetic system has overcome environmental and regulatory concerns by uncoupling oncolytic potency from avian pathogenicity. MEDI5395 has the intrinsic ability to infect and kill tumor cells and has been inserted with a GM-CSF transgene to potentiate a stronger adaptive immune response. Described here is an extensive in vitro and in vivo pharmacology package that reveals the broad oncolytic activity and immune-modulatory properties of MEDI5395 in a variety of pre-clinical models.

In vitro, MEDI5395 lytic activity in human tumor cells is associated with elevated levels of tumor selective viral replication and expression of the GM-CSF transgene. MEDI5395 infection of immune cells indicated preferential uptake of virus and subsequent self-limiting replication in myeloid cells. Infected myeloid cells expressed cell surface activation markers (e.g. PD-L1) after 24 hours and were effective carriers of virus and mediated the transfer of infectious NDV particles to tumor cells resulting in death through oncolysis. Further mechanistic studies, indicated NDV-killed tumor cells released antigens that were capable of cross-presentation by dendritic cells driving activation of tumor antigen-specific autologous T cells.

In murine models, IV delivery of NDV leads to long lasting tumor selective replication and transgene expression. MEDI5395 administration results in significant anti-tumor activity, observed in patient-derived xenograft models, and in murine syngeneic cancer models. Together, the results suggest that MEDI5395 may act to positively transform the tumor microenvironment. This, coupled to its tumor-selective oncolytic capacity, further underscore NDV as a promising multimodal cancer therapeutic platform and why FTIH studies are planned to start in 2019.

Citation Format: James A. Harper, Shannon Burke, Andrew Leinster, Nicola Rath, Xing Cheng, Hong Jin, Robert W. Wilkinson, Danielle Carroll. MEDI5395: A recombinant oncolytic virus with oncolytic and immune modulatory properties [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 1456.

Abstract 104: Mechanistic insights and dose optimization for AZD3458, a novel selective PI3Kg immuno-modulator, using a quantitative systems approach

Objectives: PI3Kγ inhibition re-polarizes macrophages to an immuno-stimulatory phenotype, thereby activating a T-cell mediated tumor immune response. AZD3458 is a highly selective PI3Kγ inhibitor. Administration of AZD3458 in combination with checkpoint inhibitors such as α-PD-(L)1 antibodies had greater anti-tumor effects (TGI 26-86%) than checkpoint inhibitor alone in 4T1, LLC, CT-26 and MC-38 syngeneic mouse models. In these, AZD3458 remodeled the tumor microenvironment (TME), reducing immunosuppressive markers (e.g in 4T1 model there was a 20% decrease in total macrophages and 50% decrease in markers of immune suppression like CD206 by flow cytometry) and promoting cytotoxic T-cell activation (e.g. in CT-26 model there was a 2-fold increase in gzmB mRNA). We developed a predictive quantitative systems pharmacology (QSP) model, to quantitatively simulate TME effects and delineate mechanistic principles underlying AZD3458 and α-PD-(L)1 synergistic effects.

Methods: The QSP model captures mechanistic, molecular and cellular interactions between PI3Kγ inhibition and checkpoint inhibitors, together with the pharmacokinetics acting on the respective targets. Features such as PI3Kγ inhibition-dependent tumor-associated macrophages, protein expression of immunosuppressive markers, reduction of MDSC activation and promotion of cytotoxic T-cell activation were included in the model. These immuno-changes were then linked to tumor cell death, resulting in macroscopic dynamic effects on tumor size. Some model parameters were taken from the literature and internal studies; some were estimated using NLME modeling of tumor size data.

Results: The model adequately described individual and population tumor size patterns. Inter-animal variability was described using a random effect on a parameter related to the ability of T cells to infiltrate the tumor in response to systemic antigen. Additionally, the model incorporated in one quantitative framework data from 4 syngeneic tumors capturing respective changes in TME conditions. Simulations for the various treatments supported the mechanistic interpretation of the observed AZD3458 and α-PD-(L)1 synergistic effects. The model was further used to simulate treatment scenarios, to infer optimal dosing and scheduling for the combination and given underlying TME conditions.

Conclusions: This study provides quantitative mechanistic insights into the links between PI3Kγ inhibition and anti-tumor immune responses, supporting our understanding of how AZD3458 may alleviate brakes in a myeloid immuno-suppressive TME and revert resistance to immunotherapy. This mechanistic understanding is critical when proceeding with dose escalation in an early clinical trial setting, as it allows to contextualize any potential compound-induced immuno-modulation in patients, for given doses and schedules.

Citation Format: Pablo Morentin Gutierrez, Yuri Kosinsky, Kirill Peskov, Ivan Azarov, Lulu Chu, Veronika Voronova, Martin Johnson, Yingxue Chen, Larissa Carnevalli, Danielle Carroll, Michele Moschetta, Teresa Klinowska, Gabriel Helmlinger. Mechanistic insights and dose optimization for AZD3458, a novel selective PI3Kg immuno-modulator, using a quantitative systems approach [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 104.

Evaluating a pilot mental health awareness for managers' training course

BACKGROUND

Despite the substantial personal and economic consequences of mental ill-health, and the relationship between mental ill-health and poor management provision, further work is needed to provide a robust evaluation of employment interventions to address mental ill-health in the workplace.

AIMS

To provide a pilot service evaluation of a UK organization's mental health awareness for managers' training provision.

METHODS

Participants were 93 employees at a UK-based organization who attended one of the three different types of, independently facilitated, half-day training courses designed to raise managers' awareness and understanding of mental health. All participants were asked to complete three questionnaires (one prior to the training session, one immediately following the training session and one 3 months after the training session). Each questionnaire contained six questions concerning participants' awareness of mental ill-health, and their confidence in dealing with mental ill-health among employees.

RESULTS

Participants reported feeling more aware of mental ill-health at work and more confident in their ability to address mental ill-health among their employees after attending mental health awareness for managers' training.

CONCLUSIONS

Although further work is needed to explore the efficacy of different types of training, the results of our pilot evaluation alongside the extant literature suggest that workplace interventions can have positive implications for good mental health.

Correlation of circulating tumor DNA (ctDNA), tissue-based genomic profiling and clinical efficacy in the biomarker directed Ph1b trial in metastatic bladder cancer (BISCAY)

4553

Background: BISCAY is a biomarker-directed Ph1b multi-arm platform study exploring the combination of targeted therapies with anti-PD-L1, Durvalumab, in advanced urothelial cancer. Methods: Next generation sequencing (NGS) of tumour tissue samples from > 380 patients(pts) was performed using the FoundationOne assay alongside IHC for PD-L1. ct DNA from pts enrolled in trial modules at treatment initiation was profiled using the Guardant Health OMNI platform assessing a panel of 500 genes. For a subset of pts, serial plasma samples were also analysed to monitor early signs of response vs. resistance and changes in ct DNA dynamics using a bespoke NGS panel of 10 genes. Results: To date 149 pts have been actively enrolled across 7 different biomarker selected and unselected treatment modules. Across all screened pts the most prevalent genomic alterations in tumour tissue were TERT promoter (65%), TP53 (59%), KMT2D 21%, KDM6A 21%, with the most common CNV CDKN2A/ B loss (32 %). All enrolled pts tested had detectable ctDNA in plasma. Similar genomic alterations, both frequency and type, were detected in both plasma ctDNA and tumour tissue with high concordance for module specific biomarkers used for patient allocation (80% (8/10) for ATM, BRCA1 and 2). Alterations in putative biomarkers predictive of response to anti-PD-L1, such as HRR/MMR alterations and high bTMB levels ( > 20mut/Mb) were observed in22% and 40% patient plasma samples, respectively. Correlations between biomarkers across modules treatment efficacy have been explored. Conclusions: All pts with advanced bladder cancer enrolled on BISCAY who were plasma profiled had detectable ctDNA; frequencies of genomic alterations (in both tumour tissue and plasma) were comparable to prior published data sets. ctDNA may be an attractive alternative to tissue-based NGS, providing comprehensive dynamic snapshots of genomic landscapes at the start and during therapy, and warrants further prospective investigation in trials.

Non-linear response of summertime marine productivity to increased meltwater discharge around Greenland

Runoff from the Greenland Ice Sheet (GrIS) is thought to enhance marine productivity by adding bioessential iron and silicic acid to coastal waters. However, experimental data suggest nitrate is the main summertime growth-limiting resource in regions affected by meltwater around Greenland. While meltwater contains low nitrate concentrations, subglacial discharge plumes from marine-terminating glaciers entrain large quantities of nitrate from deep seawater. Here, we characterize the nitrate fluxes that arise from entrainment of seawater within these plumes using a subglacial discharge plume model. The upwelled flux from 12 marine-terminating glaciers is estimated to be >1000% of the total nitrate flux from GrIS discharge. This plume upwelling effect is highly sensitive to the glacier grounding line depth. For a majority of Greenland's marine-terminating glaciers nitrate fluxes will diminish as they retreat. This decline occurs even if discharge volume increases, resulting in a negative impact on nitrate availability and thus summertime marine productivity.

Structured illumination microscopy combined with machine learning enables the high throughput analysis and classification of virus structure

Optical super-resolution microscopy techniques enable high molecular specificity with high spatial resolution and constitute a set of powerful tools in the investigation of the structure of supramolecular assemblies such as viruses. Here, we report on a new methodology which combines Structured Illumination Microscopy (SIM) with machine learning algorithms to image and classify the structure of large populations of biopharmaceutical viruses with high resolution. The method offers information on virus morphology that can ultimately be linked with functional performance. We demonstrate the approach on viruses produced for oncolytic viriotherapy (Newcastle Disease Virus) and vaccine development (Influenza). This unique tool enables the rapid assessment of the quality of viral production with high throughput obviating the need for traditional batch testing methods which are complex and time consuming. We show that our method also works on non-purified samples from pooled harvest fluids directly from the production line.

Aquatic treadmill water level influence on pelvic limb kinematics in cranial cruciate ligament-deficient dogs with surgically stabilised stifles

OBJECTIVE

To compare pelvic limb joint kinematics and temporal gait characteristics during land-based and aquatic-based treadmill walking in dogs that have undergone surgical stabilisation for cranial cruciate ligament deficiency.

MATERIALS AND METHODS

Client-owned dogs with surgically stabilised stifles following cranial cruciate ligament deficiency performed three walking trials consisting of three consecutive gait cycles on an aquatic treadmill under four water levels. Hip, stifle and hock range of motion; peak extension; and peak flexion were assessed for the affected limb at each water level. Gait cycle time and stance phase percentage were also determined.

RESULTS

Ten client-owned dogs of varying breeds were evaluated at a mean of 55·2 days postoperatively. Aquatic treadmill water level influenced pelvic limb kinematics and temporal gait outcomes. Increased stifle joint flexion was observed as treadmill water level increased, peaking when the water level was at the hip. Similarly, hip flexion increased at the hip water level. Stifle range of motion was greatest at stifle and hip water levels. Stance phase percentage was significantly decreased when water level was at the hip.

CLINICAL SIGNIFICANCE

Aquatic treadmill walking has become a common rehabilitation modality following surgical stabilisation of cranial cruciate ligament deficiency. However, evidence-based best practice guidelines to enhance stifle kinematics do not exist. Our findings suggest that rehabilitation utilising a water level at or above the stifle will achieve the best stifle kinematics following surgical stifle stabilisation.

Abstract 4562: Exploring the immune stimulatory properties of oncolytic Newcastle Disease Virus

Newcastle Disease Virus (NDV) is an avian paramyxovirus, which has significant oncolytic activity against mammalian cancers. It is multi-modal in its anti-tumour activity and offers a tumour selective, self-propagating therapeutic with oncolytic activity and immunostimulatory properties. Within the tumour itself, NDV infection is able to modulate the immune suppressive microenvironment and induce positive anti-tumour inflammatory responses. Additionally, we have enhanced the immune modulatory properties of NDV by engineering the virus to express granulocyte/macrophage colony-stimulating factor (GM-CSF). To better understand the immune modulatory mechanisms by which NDV infection is able to alter the tumour microenvironment we investigated the responses of normal human PBMCs and isolated immune cell populations following NDV exposure. Using flow cytometry, cytokine and gene expression analysis we demonstrated activation of the innate immune cells and a robust type I IFN and pro-inflammatory response. 24 hours post infection, innate immune cells (macrophages, natural killer cells and dendritic cells) had upregulated cell surface activation markers and secreted high levels of cytokines in a dose-dependent fashion. Furthermore, by using NDV constructs encoding fluorescent proteins we showed, in a specific subset of myeloid cells, the preferential uptake of virus and subsequent self-limiting viral replication. In a co-culture system, these infected myeloid cells were able to function as ‘virus cellular carriers’ and were able to mediate the efficient transfer of infectious NDV to tumour cells resulting in their oncolytic death. To further investigate the ability of NDV to infect, spread and kill tumour cells in vivo, we utilised tissue slice cultures of fresh patient samples. These studies demonstrated virus replication and transgene expression in tumour slices, as well as the uptake of virus in a small fraction of specific cells in slices of normal liver. Moreover, evidence that NDV was able to alter the tumour microenvironment could be demonstrated in such cultures by sampling the culture supernatants over time. By investigating the immune modulatory properties of NDV in vitro and in vivo we will gain greater insight and understanding of the anti-cancer properties of NDV. This work will also help guide the selection of transgenes for next generation approaches to augment the inherent immunostimulatory properties of NDV, and help inform clinical dosing options such as intravenous infusion or cell-based delivery.

Citation Format: Shannon Burke, Ruth Franks, James Harper, Jon Travers, Christel Navarro, Xing Cheng, Robert Wilkinson, Hong Jin, Danielle Carroll. Exploring the immune stimulatory properties of oncolytic Newcastle Disease Virus [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 4562. doi:10.1158/1538-7445.AM2017-4562

Abstract 4556: MEDI5395: An armed oncolytic Newcastle disease virus

Oncolytic viruses are live, replication-competent viruses that infect and/or replicate selectively in tumour cells leading to the destruction of the infected cell. Cell lysis occurs as a natural consequence of the viral life cycle and released virions can infect and kill neighbouring tumour cells leading to an amplified therapeutic effect. Oncolysis has the added benefit of releasing multiple tumour antigens that may further induce an immune-mediated therapeutic response. Newcastle Disease Virus (NDV) is an avian paramyxovirus, which has proven safety and demonstrated efficacy against a variety of preclinical cancer models and in PhI clinical studies as an oncolytic agent, oncolysate or whole cell vaccine. Using reverse genetics, we have generated a recombinant strain of NDV that overcomes environmental and regulatory concerns uncoupling oncolytic potency and avian pathogenicity. Furthermore we have enhanced the immune modulatory properties of NDV by engineering the virus to express granulocyte/macrophage colony-stimulating factor (GM-CSF). We have evaluated the biological characteristics of recNDVGM-CSF (MEDI5395) in vivo and in vitro. MEDI5395 selectively replicates in and kills a wide variety of human and mouse tumour cell lines. Additionally infection of cancer cells with MEDI5395 results in the increased production and secretion of pro-inflammatory cytokines and chemokines which are able to recruit mediators of both the innate and adaptive immune responses. MEDI5395 is a potent activator of the type I interferon response. In vivo, using a range of syngeneic and xenograft models we have demonstrated that NDV treatment has robust anti-tumour activity. In a HT1080 fibrosarcoma xenograft model a single administration (intra-tumoural or systemic) was able to cure 80% of tumour bearing mice. In syngeneic mouse tumour models, which support minimal viral replication MEDI5395 treatment causes significant changes in the local immune suppressive microenvironment and results in long-lasting anti-tumour immune responses. These responses are further enhanced in models that permit greater replication and also when combined with immune checkpoint blockade. The inherent properties of NDV (self-propagation, tumour-selective replication, and immunostimulatory properties) coupled with the ability to genetically engineer NDV to express therapeutic transgenes may provide a multi-modal attack on the tumour, delivering greater benefit to patients.

Citation Format: Danielle Carroll, James Harper, Travers Jon, Shannon Burke, Ruth Franks, Christel Navarro, Xing Cheng, Robert Wilkinson, Hong Jin. MEDI5395: An armed oncolytic Newcastle disease virus [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 4556. doi:10.1158/1538-7445.AM2017-4556

Abstract 4203: Non-invasive imaging of tumor cell death induced by a TRAILR2 agonist

Imaging tumour cell death can give an early indication of treatment efficacy. Tumour necrosis factor (TNF)-related apoptosis-inducing ligand receptor2 (TRAILR2) is a member of the TNF receptor superfamily, which interacts with death receptors (DRs) and induces apoptosis in a broad range of cancer cells but not normal cells[1]. MEDI3039, a newly described agonist of TRAILR2, was used to induce tumour cell death. A NIRF fluorophore-labelled phosphatidylserine (PS)-binding protein (∼15kDa), the C2A domain of Synaptotagmin-I (C2Am-750), which binds to the PS exposed by apoptotic and necrotic cells, was used to image MEDI3039-induced cell death[2]. Non-specific binding was assessed using a site-directed mutant that is inactive in PS binding, which was conjugated to a different fluorophore (iC2Am-680).

Binding of C2Am-750 to MEDI3039-treated human colon and breast adenocarcinoma cells in vitro (Colo205 and MDA-Dual respectively) was assessed by flow cytometry and confocal microscopy. Both methods showed that C2Am-750 labelled MEDI3039-treated Colo205 cells, while the inactive iC2Am-680 showed only low non-specific binding. C2Am-750 and iC2Am-680 were also used to monitor the effect of treatment in a Colo205 xenograft model. One cohort of mice (n = 5) received a single dose of MEDI3039 (0.4 mg/kg), while another untreated cohort (n = 5) served as a control group. All mice received a single i.v. injection of a 1:1 mixture of 0.1 μmole/kg C2Am-750 and iC2Am-680 at 16 h after drug treatment, followed by whole body fluorescence imaging (FLI) measurements using an IVIS200 camera at 0 and 3 h post probe injection. FLI measurements in MEDI3039-treated Colo205 tumours showed significant increases in the uptake of C2Am-750 relative to iC2Am-680, both in vivo (4-9 fold, P value <0.0001) and ex vivo (7-11 fold, P value <0.0001). Uptake of iC2Am-680 was low in both treated and untreated groups. Subsequent histological analyses showed that the C2Am-750 signal was strongly correlated with both cleaved caspase-3 and TUNEL staining of dead cells.

NIRF fluorophore-labelled C2Am showed a favourable biodistribution profile, with good tumour penetration and quick clearance of unbound material in vivo. The probe can be used to investigate the efficacy of targeted therapy, or other anti-tumour therapies, at an early stage following treatment.

1. Prasad, S., Kim, J.H., Gupta, S.C. & Aggarwal, B.B. Targeting death receptors for TRAIL by agents designed by Mother Nature. Trends in pharmacological sciences 35, 520-536 (2014).

2. Alam, I.S., Neves, A.A., Witney, T.H., Boren, J. & Brindle, K.M. Comparison of the C2A domain of synaptotagmin-I and annexin-V as probes for detecting cell death. Bioconjugate chemistry 21, 884-891 (2010).

Citation Format: Bangwen Xie, Andre Neves, Stefanie R. Mullins, David Tice, Danielle Carroll, Robert W. Wilkinson, Kevin M. Brindle. Non-invasive imaging of tumor cell death induced by a TRAILR2 agonist. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4203.

Abstract 2234: Exploring the oncolytic potential of Newcastle Disease Virus

Oncolytic viruses are live, replication-competent viruses that infect and/or replicate selectively in tumour cells leading to the destruction of the infected cell. Cell death occurs as a natural consequence of the viral life cycle and newly produced virions can infect and kill neighbouring tumour cells leading to an amplified therapeutic effect. Oncolysis has the added benefit of potentially producing novel tumour antigens that can induce an immune-mediated therapeutic response.

Newcastle Disease Virus (NDV) is an avian paramyxovirus, which has proven safety and demonstrated efficacy against a variety of mammalian cancers in PhI clinical studies. Using reverse genetics, we generated a recombinant strain of NDV that overcomes environmental and regulatory concerns uncoupling oncolytic potency and avian pathogenicity. We have additionally inserted the GM-CSF gene in order to maximize anti-tumour immune response and provide an in situ, patient/tumour- specific vaccine, combined with potent oncolysis. We have evaluated the biological characteristics of recNDVGM-CSF in vivo and in vitro. In vitro recNDVGM-CSF selectively replicates in and kills a wide variety of tumour cell types. In vivo, using a fibrosarcoma model that supports viral replication, a single administration (intra-tumoural or systemic) was able to cure 80% of tumour bearing mice. Additionally, following IV administration recNDVGM-CSF localises to and replicates within the tumour leading to a localised GM-CSF production within the tumour. The inherent properties of NDV (self-propagation, tumour-selective replication, immune activation) coupled with the ability to genetically engineer NDV to express therapeutic transgenes may provide a multi-modal attack on the tumour, delivering greater benefit to patients.

Citation Format: James A. Harper, Jon Travers, Ruth Franks, Shannon Burke, Christel Navarro, Cheng Xing, Weijia Wang, Qi Xu, Robert W. Wilkinson, Hong Jin, Danielle Carroll. Exploring the oncolytic potential of Newcastle Disease Virus. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2234.

Phage display and hybridoma generation of antibodies to human CXCR2 yields antibodies with distinct mechanisms and epitopes

Generation of functional antibodies against integral membrane proteins such as the G-protein coupled receptor CXCR2 is technically challenging for several reasons, including limited epitope accessibility, the requirement for a lipid environment to maintain structure and their existence in dynamic conformational states. Antibodies to human CXCR2 were generated by immunization in vivo and by in vitro selection methods. Whole cell immunization of transgenic mice and screening of phage display libraries using CXCR2 magnetic proteoliposomes resulted in the isolation of antibodies with distinct modes of action. The hybridoma-derived antibody fully inhibited IL-8 and Gro-α responses in calcium flux and β-arrestin recruitment assays. The phage-display derived antibodies were allosteric antagonists that showed ligand dependent differences in functional assays. The hybridoma and phage display antibodies did not cross-compete in epitope competition assays and mapping using linear and CLIPS peptides confirmed that they recognized distinct epitopes of human CXCR2. This illustrates the benefits of using parallel antibody isolation approaches with different antigen presentation methods to successfully generate functionally and mechanistically diverse antagonistic antibodies to human CXCR2. The method is likely to be broadly applicable to other complex membrane proteins.

Abstract 427: Host and tumoral CXCR2 signaling contributes to tumor growth

Chemokines are essential mediators of leukocyte migration and inflammation. Additionally they play an important role in tumour growth. The G-protein coupled receptor, CXCR2, and its ligands (CXCL 1,2,3,5,6,7 and IL8) have been shown to promote tumour initiation and growth, chemo-resistance, angiogenesis and immune cell infiltration (neutrophil, myeloid derived suppressor cells (MDSCs) and macrophages) into the tumour microenvironment. However the contribution of host and tumour CXCR2 has not been elucidated.

We have developed both murine and human specific anti-CXCR2 antibodies alongside a humanised CXCR2 transgenic mouse to address the contribution of host and tumour CXCR2 signalling to tumour growth and maintenance. In pre-clinical tumours, granulocytic cells (neutrophils and MDSCs) within the tumour increase with size, in parallel with alteration in cell numbers observed within the spleen, peripheral blood and bone marrow.

Inhibition of host CXCR2 has a dramatic impact on peripheral neutrophil levels, as well as their ability to become activated.

In pre-clinical tumour models, inhibition of CXCR2 results in tumour growth inhibition. Contribution of host or tumour cells to the effect of CXCR2 blockade was model dependent. In the EL4 murine lymphoma model, only inhibition of host/peripheral CXCR2 was able to impact tumour growth. Whereas, in other murine syngeneic models (CT26 and B16), both host and tumour CXCR2 play a role in tumour growth. This was further demonstrated in an NSCLC patient derived xenograft, where the contribution of tumour CXCR2 was stronger than the host.

Collectively our data show that CXCR2 inhibition (alone or in combination) has potential to influence growth of a number of tumour types. Future work is focused on understanding the mechanisms underlying the effects of CXCR2 inhibition, which remain key to developing it as an effective anti-cancer therapeutic.

Citation Format: Danielle Carroll, James Harper, Karen McDaid, Ruth Franks, Catherine Eberline, Jane Kendrew, Richard Sainson, Judith Anderton, Chris Rossant, Karen Coffman, Ching Ching Leow, Ivan Inigo, Mitchell Reville, Jacintha Shenton, Lesley Young, Simon Barry. Host and tumoral CXCR2 signaling contributes to tumor growth. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 427. doi:10.1158/1538-7445.AM2015-427

Antimicrobial Resistance in Wildlife: Implications for Public Health

The emergence and spread of antimicrobial-resistant (AMR) bacteria in natural environments is a major concern with serious implications for human and animal health. The aim of this study was to determine the prevalence of AMR Escherichia coli (E. coli) in wild birds and mammalian species. Thirty faecal samples were collected from each of the following wildlife species: herring gulls (Larus argentatus), black-headed gulls (Larus ridibundus), lesser black-back gulls (Larus fuscus), hybrid deer species (Cervus elaphus x Cervus nippon) and twenty-six from starlings (Sturnus vulgaris). A total of 115 E. coli isolates were isolated from 81 of 146 samples. Confirmed E. coli isolates were tested for their susceptibility to seven antimicrobial agents by disc diffusion. In total, 5.4% (8/146) of samples exhibited multidrug-resistant phenotypes. The phylogenetic group and AMR-encoding genes of all multidrug resistance isolates were determined by PCR. Tetracycline-, ampicillin- and streptomycin-resistant isolates were the most common resistant phenotypes. The following genes were identified in E. coli: bla(TEM), strA, tet(A) and tet(B). Plasmids were identified in all samples that exhibited multidrug-resistant phenotypes. This study indicates that wild birds and mammals may function as important host reservoirs and potential vectors for the spread of resistant bacteria and genetic determinants of AMR.

Automated breast segmentation of fat and water MR images using dynamic programming

RATIONALE AND OBJECTIVES

To develop and test an algorithm that outlines the breast boundaries using information from fat and water magnetic resonance images.

MATERIALS AND METHODS

Three algorithms were implemented and tested using registered fat and water magnetic resonance images. Two of the segmentation algorithms are simple extensions of the techniques used for contrast-enhanced images: one algorithm uses clustering and local gradient (CLG) analysis and the other algorithm uses a Hessian-based sheetness filter (HSF). The third segmentation algorithm uses k-means++ and dynamic programming (KDP) for finding the breast pixels. All three algorithms separate the left and right breasts using either a fixed region or a morphological method. The performance is quantified using a mutual overlap (Dice) metric and a pectoral muscle boundary error. The algorithms are evaluated against three manual tracers using 266 breast images from 14 female subjects.

RESULTS

The KDP algorithm has a mean overlap percentage improvement that is statistically significant relative to the HSF and CLG algorithms. When using a fixed region to remove the tissue between breasts with tracer 1 as a reference, the KDP algorithm has a mean overlap of 0.922 compared to 0.864 (P < .01) for HSF and 0.843 (P < .01) for CLG. The performance of KDP is very similar to tracers 2 (0.926 overlap) and 3 (0.929 overlap). The performance analysis in terms of pectoral muscle boundary error showed that the fraction of the muscle boundary within three pixels of reference tracer 1 is 0.87 using KDP compared to 0.578 for HSF and 0.617 for CLG. Our results show that the performance of the KDP algorithm is independent of breast density.

CONCLUSIONS

We developed a new automated segmentation algorithm (KDP) to isolate breast tissue from magnetic resonance fat and water images. KDP outperforms the other techniques that focus on local analysis (CLG and HSF) and yields a performance similar to human tracers.

Effects of replacing thiophene with 5,5-dimethylcyclopentadiene in alternating poly(phenylene), poly(3-hexylthiophene), and poly(fluorene) copolymer derivatives

Replacing alternating thiophene repeat units with 5,5-dimethylcyclopentadiene alternatives influences the physicochemical properties of π-conjugated copolymers.

Type a behaviours and heart disease: epidemiological and experimental foundations

This paper critically examines three strands of evidence that concern the relationship between type A behaviours and coronary heart disease; prospective epidemiological studies of healthy populations, studies of those at high risk for coronary heart disease, and angiographic studies of atherosclerosis. The first of these would seem to provide the strongest test. Methodological and conceptual issues mean that the results of studies using the other methods should be interpreted with care. It is concluded that there is relatively strong evidence of an association between Type A behaviour as measured by Structured Interview and coronary heart disease. Hostility and anger appear to be the most powerful determinants of CHD. However, it is likely that they interact with other type A behaviours and related environmental factors in determining risk.

A comparison of the quality of life of vulnerable young males with severe emotional and behaviour difficulties in a residential setting and young males in mainstream schooling

One hundred and seventy-four males completed a quality of life (QoL) assessment utilizing, a generic paediatric quality of life inventory (PedsQL) and the short form (36) health survey (SF36). The adolescents aged 13-16 years were in a Scottish Centre for young males with social, emotional, behavioural and educational problems. To identify similarities and differences, a comparison group (n = 110) of males in the third and fourth year in a mainstream secondary school were also administered the PedsQL and the SF36 self-rating scales. The effectiveness of the PedsQL and the SF36 for assessing QoL for adolescent males was investigated. There were significant differences between the groups in the Centre and between the Centre groups and the comparison group in terms of their QoL. The results between the groups were found in the PedsQL subscales 'physical functioning' where secure > comparison (P = 0.04); secure > residential (P = 0.008); and PedsQL subscale 'social functioning' day > comparison (P = 0.026); secure > comparison (P = 0.037). SF36 subscales 'role physical functioning' secure > residential (P < 0.001); day > residential (P < 0.001). SF36 'role mental functioning' day > residential (P = 0.001). This study provides a unique insight into the complex dimensions influencing the QoL of this specific group of young people.