Abstract P2-03-17: Fluoroestradiol (FES) and Fluorodeoxyglucose (FDG) PET imaging in patients with ER+, HER2+ or HER2- metastatic breast cancer

Background: 18F-Fluorodeoxyglucose (FDG) has long been used for measuring tumor glycolytic activity in clinical PET imaging. The FDA recently approved 18F-Fluoroestradiol (FES) (Cerianna) as a PET imaging tracer for characterizing disease in patients with estrogen-receptor positive (ER+) breast cancer. As FES PET enters clinical practice it is important to establish its utility in the full population of hormone-receptor positive patients, including for patients with human epidermal growth factor 2 (HER2)-overexpressing tumors. Patients with HER2-positive metastatic breast cancer have historically been treated with combination cytotoxic and HER2-directed therapy, with the understanding that HER2 is the primary driver in this disease state. This retrospective study examined uptake in matched lesions for both FES and FDG PET and compared activity in patients with HER2 positive versus HER2 negative metastatic breast cancer.

Methods: Patients were selected from the UW research database who had a history of biopsy-proven primary ER+ breast cancer as well as FES and FDG PET scans within 30 days. We examined FDG and FES scans and recorded SUVmax in up to 16 matched lesions between the two scans. Patients were also divided by HER2 status (+/-). In addition, a subset of patients who underwent at least 2 paired FDG and FES scans were reviewed.

Results: 270 matched FDG and FES scans were analyzed in 216 patients with history of ER+, and HER2+ or HER2- breast cancer who were not part of an ongoing clinical trial. 158 (73%) had ductal disease, 38 (18%) had lobular disease. 183 (85%) had HER2- breast cancer. Of the 33 patients who had HER2+ breast cancer, 28 (85%) had ductal carcinoma. 40 patients underwent serial scans, allowing tracking over multiple timepoints. A total of 1323 metastatic sites were recorded (average = 5/scan (range 1,16)), with the majority (71%) representing bony lesions. No difference in quantitative FES or FDG avidity was observed between soft tissue and osseous sites. FES and FDG SUVmax were similar among patients with either HER2- or HER2+ breast cancer (Table 1). Among 40 patients with multiple paired FDG and FES scans, 26 (65%) had 2 scans while the remaining 14 had 3, with FES avidity remaining stable over time. There was no correlation between FES or FDG scans and HER2 status.

Conclusion: In a cohort of ER+, HER2+ and HER2- patients undergoing concurrent FDG and FES PET scans, FDG and FES activity was similar regardless of HER2 status. FES uptake in both HER2- and HER2+ patients and stability over time in serial scans suggest that HER2 does not affect ER density. This suggests that in many patients with so-called “triple positive” disease, endocrine therapy may offer a powerful primary rather than ancillary tool in select patients. FES combined with FDG PET may offer utility in predicting and assessing response to therapy in this patient population.

Table 1. FES and FDG uptake in patients with HER2- or HER2+ disease

Citation Format: Natasha Hunter, Lanell M. Peterson, David A. Mankoff, Mark Muzi, Delphine Chen, William R. Gwin, Shaveta Vinayak, Nancy E Davidson, Jennifer M. Specht, Hannah Linden. Fluoroestradiol (FES) and Fluorodeoxyglucose (FDG) PET imaging in patients with ER+, HER2+ or HER2- metastatic 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 P2-03-17.

Abstract GS3-03: GS3-03 ARV-471, a PROTAC® estrogen receptor (ER) degrader in advanced ER-positive/human epidermal growth factor receptor 2 (HER2)-negative breast cancer: phase 2 expansion (VERITAC) of a phase 1/2 study

Background: ARV-471 is a selective, orally administered PROteolysis TArgeting Chimera (PROTAC®) protein degrader that targets wild-type and mutant ER. ARV-471 is being evaluated in patients with ER+/HER2- locally advanced or metastatic breast cancer in a first-in-human phase 1/2 study (NCT04072952). In the phase 1 dose escalation, ARV-471 monotherapy (dose range: 30–700 mg total daily dose) showed a manageable safety profile in patients who had previously received endocrine therapy and a cyclin-dependent kinase (CDK) 4/6 inhibitor. The clinical benefit rate (CBR; rate of confirmed complete or partial response or stable disease ≥24 weeks) was 40% (95% CI: 26–56) in 47 evaluable patients. The phase 2 expansion portion of the study (VERITAC) evaluated 2 doses of ARV-471.Methods: In VERITAC, ARV-471 monotherapy was administered at doses of 200 mg once daily (QD) or 500 mg QD to patients with ER+/HER2- locally advanced/metastatic breast cancer who had received ≥1 prior endocrine therapy for ≥6 months, ≥1 CDK4/6 inhibitor, and ≤1 chemotherapy regimen. The primary endpoint of CBR was evaluated in patients enrolled ≥24 weeks prior to the data cutoff. Results: As of June 6, 2022, 71 patients received ARV-471 (200 mg QD [n=35]; 500 mg QD [n=36]) in VERITAC. Across all treated patients, 69 (97.2%) were female and median age was 60 y (range: 41–86). Patients had received a median of 4 prior regimens in all settings (range: 1–10); 100% had prior CDK4/6 inhibitors, 78.9% had prior fulvestrant, and 73.2% had prior chemotherapy. ARV-471 was well tolerated at both doses, with most treatment-related adverse events (TRAEs) grade 1/2; the most common TRAEs were fatigue and nausea (Table). In all, 3 patients (1 in the 200 mg QD cohort and 2 in the 500 mg QD cohort) discontinued ARV-471 due to treatment-emergent adverse events (TEAEs); 3 patients had ARV-471 dose reductions due to TEAEs (all from 500 mg QD to 400 mg QD). CBR was 37.1% (95% CI: 21–55) in 35 evaluable patients treated at 200 mg QD and 38.9% (95% CI: 23–57) in 36 evaluable patients treated at 500 mg QD. CBR in evaluable patients with mutant ESR1 in the 200 mg QD (n=19) and 500 mg QD (n=22) cohorts was 47.4% (95% CI: 24–71) and 54.5% (95% CI: 32–76), respectively. Conclusions: In the phase 2 VERITAC expansion cohorts of patients with ER+/HER2- locally advanced/metastatic breast cancer and prior CDK4/6 inhibitor treatment, ARV-471 monotherapy showed evidence of clinical activity based on CBR, which was further enhanced in the subgroup with ESR1 mutations. The manageable AE profile observed in the phase 1 portion of the study was maintained during cohort expansion at doses of 200 mg QD and 500 mg QD. Additional analyses are ongoing.Table. TRAEs reported in ≥10% of patients overall aNo grade 3/4 TRAE occurred in >1 patient. AST=aspartate aminotransferase

Citation Format: Anne F. Schott, Sara Hurvitz, Cynthia Ma, Erika Hamilton, Rita Nanda, George Zahrah, Natasha Hunter, Antoinette R. Tan, Melinda Telli, Jesus Anampa Mesias, Rinath Jeselsohn, Pamela Munster, Haolan Lu, Richard Gedrich, Cecile Mather, Janaki Parameswaran, Hyo S. Han. GS3-03 ARV-471, a PROTAC® estrogen receptor (ER) degrader in advanced ER-positive/human epidermal growth factor receptor 2 (HER2)-negative breast cancer: phase 2 expansion (VERITAC) of a phase 1/2 study [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 GS3-03.

Abstract PD9-08: ImPrint immune signature in 10,000 early-stage breast cancer patients from the real-world FLEX database

BACKGROUND: Immune checkpoint inhibitors in combination with chemotherapy have demonstrated an improvement of pathologic complete response (pCR) in patients with HR-HER2- and MammaPrint (MP) High Risk, HR+HER2- tumors in the I-SPY2 TRIAL. However, not all patients benefit from immune checkpoint blockade and these new agents come with additional financial burden and significant long-lasting side effects such as adrenal insufficiency. Thus, it is imperative to better understand who benefits. Response Predictive Subtypes (RPS) were developed in the I-SPY2 TRIAL using pre-treatment expression data from 987 MP High Risk patients; 39% of HR+HER2- tumors and 63% of HR-HER2- tumors were identified as immune sensitive. In I-SPY2.2, RPS tumor classification uses ImPrint, a 53-gene signature that has been independently validated to predict the likelihood of a pCR with PD1-PDL1 immune checkpoint inhibitors with high sensitivity and specificity. Using a real-world dataset of 10,000 patients enrolled in the FLEX trial, we identified immune sensitive (ImPrint+) patients within immunohistochemistry (IHC) subtypes and within MP and BluePrint (BP) subgroups.

METHODS: FLEX (NCT03053193) is an ongoing registry trial with 97 sites open in the United States and 2 international sites. Patients enrolled in FLEX have early-stage breast cancer and receive standard of care MP testing with or without BP molecular subtyping and consent to clinically annotated full genome data collection. MP is a 70-gene risk of distant recurrence signature that classifies patients as Low Risk or High Risk. MP High Risk can be further stratified into High 1 and High 2, which have demonstrated differences in chemosensitivity and pCR rates in the I-SPY2 TRIAL (NCT01042379). BP, an 80-gene molecular subtyping signature, categorizes patients’ tumors as Luminal-, HER2- or Basal-Type.

RESULTS: Of the 10,021 patients, 9.1% of the FLEX patient population are ImPrint+ and are predicted to have a meaningful pCR rate with immune checkpoint inhibitors. Younger (≤ 50 years) or pre/peri-menopausal patients, patients with larger or node-positive tumors, and patients of Black or Latin race/ethnicity independently had a higher likelihood of having ImPrint+ tumors (Table 1). ImPrint+ tumors were identified in all clinical subtypes by IHC. There is a higher likelihood of ImPrint+ tumors being MP High 2 or BP Basal-Type tumors. Within BP Basal tumors, 74.7% of HR+ and 66.0% of HR- tumors were ImPrint+.

CONCLUSIONS: The focus of immune therapy trials has been on patients with HR-HER2-, MP High Risk patients. Indeed, most patients who are predicted to benefit have MP High 2 or BP Basal-Type tumors, including some HR+ patients, which is consistent with I-SPY2 results. Importantly, this large real-world dataset enables the identification of populations who may benefit from immune therapy outside of traditional clinical trial populations and supports the testing of checkpoint inhibitors in the immune-positive subtype. Younger women and patients of Black or Latin race/ethnicity who typically have more aggressive tumors also have higher proportions of ImPrint+ tumors. Thus, it is critical that these populations be included in clinical trials. This first look at immune sensitivity in over 10,000 FLEX patients with ImPrint generates preliminary data and hypotheses that will be explored in future FLEX substudies, including an analysis of lobular cancers and long-term outcomes in ImPrint+ patients across all races and ages.

Table 1. Clinical characteristics of ImPrint+ and ImPrint- tumors.

Citation Format: Adam M. Brufsky, Midas Kuilman, Rita Mukhtar, Denise M. Wolf, Christina Yau, Joyce O’Shaughnessy, Cathy Graham, Vijayakrishna K. Gadi, Pat Whitworth, Alexander Hindenburg, Ian Grady, Gordon Srkalovic, Kent Hoskins, Ajay Dhakal, Cynthia Ma, Natasha Hunter, Jennifer Crozier, Blanche Mavromatis, Lorenza Mittempergher, Christine Finn, Shraddha Modh, Erin B. Yoder, Patricia Dauer, Andrea Menicucci, Bas van der Baan, William Audeh, Laura J. Esserman. ImPrint immune signature in 10,000 early-stage breast cancer patients from the real-world FLEX database [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 PD9-08.

Abstract P2-03-25: Pilot study to evaluate circulating tumor DNA (ctDNA) to PET/CT imaging using 18F-Fluorodeoxyglucose (FDG) and 18F-Fluoroestradiol (FES) PET/CT imaging as biomarkers in patients with metastatic breast cancer

Background: 18F-FES is an FDA-approved estrogen analogue PET imaging tracer (Cerianna) which measures tumor estrogen receptor (ER) expression at multiple tumor sites simultaneously and predicts response to endocrine therapy. 18F-FDG is a commonly used glucose PET imaging tracer which measures glycolytic metabolic activity in tumors. Elevated plasma ctDNA has been associated with an increased risk of relapse and can identify actionable genomic alterations. This pilot research study explored the relationship between somatic copy-number variants (CNVs) and cell-free DNA mass using low-pass-whole-genome (LPWG) ctDNA in the blood to FES and FDG PET/CT findings with both qualitative and quantitative image analysis in metastatic breast cancer patients.

Methods: Two(2) 10ml Streck tubes were collected from 20 patients with metastatic ER+ breast cancer +/-30 days of their FDG-PET/CT scan (n=19) or their FES-PET/CT scan (n=9). 8 patients had both scans. Somatic mutations were assessed using comprehensive genomic profiling of tissue samples from 19 patients using the clinically validated UW-Oncoplex assay. Qualitative analysis included detection of LPWG ctDNA, presence of PIK3A mutations in tissue, and intensity of uptake in PET/CT imaging. LPWG ctDNA of blood samples evaluated ctDNA mass and CNVs that comprised at least 8% of total ctDNA. Total lesion glycolysis (TLG) in FDG scans and total lesion estrogen receptors (TLER) in FES scans were calculated using a dedicated workflow in MiM software (MiM Software Inc. Cleveland OH). Quantitative analysis included the circulating fraction (ctDNA), PET/CT SUVmax of the index lesion, number of lesions, TLG and TLER. For TLG, the threshold for determining measurable lesions was calculated using liver SULmean + 1.5*SD. The threshold for TLER was calculated using SUVmean of the mediastinal blood pool. The ctDNA fraction and the number of lesions for both FDG and FES were each ranked into 3 categories. FDG and FES data (SUVmax of index lesion, # of lesions, and TLG or TLER) were correlated to the calculated ctDNA fraction values. TLG and TLER were also correlated to each other.

Results: ctDNA was classified as no ctDNA present (n=9), ctDNA present (n=8) and indeterminate (n=3). Average neoplastic ctDNA fraction was 0.114 (range 0.03-0.423). PIKC3A mutations were: 10 absent and 9 present. Ranked categories for ctDNA fraction, FDG TLG and FES TLER are shown in Table 1. Table 2 shows results of FDG and FES analysis and correlation with ctDNA. Ranked ctDNA findings correlated with both the FDG number of lesions (R2=0.69) and TLG (R2=0.83), but not the SUVmax of the index lesion (R2=0.29). Correlation decreased for ctDNA versus FES number of lesions (R2=0.51), TLER (R2=0.61), and SUVmax of index lesion (R2=0.16). TLG and TLER significantly correlated with the 8 patients that had both an FDG and FES PET/CT scan (R2=0.77).

Conclusions: In this pilot study, FDG TLG showed a significant correlation with ctDNA. There is an encouraging association with ctDNA fraction and number of FDG lesions and with ctDNA fraction and extent of FES avid disease (TLER) in the 9 patients that had FES.

Research Support: RG1005258

Table 1. Categorical rankings for qualitative analysis of ctDNA, TLG and TLER

Table 2. FDG and FES imaging results and correlation with ctDNA

Citation Format: Natasha Hunter, Lanell M. Peterson, Mark Muzi, Eric Q. Konnick, Jonathan Reichel, Paul Kinahan, Jennifer M. Specht, Rachel Yung, William R. Gwin, Hannah Linden, Christina Tran. Pilot study to evaluate circulating tumor DNA (ctDNA) to PET/CT imaging using 18F-Fluorodeoxyglucose (FDG) and 18F-Fluoroestradiol (FES) PET/CT imaging as biomarkers in patients with metastatic 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 P2-03-25.

13 FIGHTING FRAILTY FROM FOUNDATION UP

Background

In 2021 the UK Foundation Programme introduced a new curriculum for UK Foundation Doctors (FDs). For the first time, frailty has been designated as a core learning topic. This means that all FDs are expected to undertake dedicated frailty training. Subsequently, a virtual frailty workshop was developed and delivered by Zoom to all F2 doctors in Northern Ireland. Entitled ‘Taking a Better Approach to the Frailer Adult’, the three hour workshop familiarises FDs with core frailty concepts including Comprehensive Geriatric Assessment (CGA), delirium, and deprescribing.

Methods

All attendees completed an online survey after workshops. They were asked to provide free text comments about what they felt were the most successful and useful aspects of the workshop. Attendees were also were asked to numerically rate the workshop relevance, handout quality and venue suitability.

Results

The frailty workshop was delivered to 222 F2 doctors over eight months. On average, attendees rated the relevance of the workshop as 4.8/5. Attendees rated the quality of the handouts and the venue suitability at 4.4/5 and 4.2/5 respectively. Thematic analysis of qualitative feedback on the most successful elements of the workshop showed that attendees found the session to be useful, relevant, and engaging, with particular preference for use of cases. For example, one attendee wrote that, ‘use of cases and breakout rooms to discuss CGA [allowed] us to get a feel of how this applies to patients in clinical settings”. Thematic analysis of qualitative feedback on what could be done to make the workshop better showed attendees had preferences for greater use of cases and smaller breakout rooms. This feedback was used to develop and improve the workshop.

Conclusion

FDs value teaching on frailty and consider it highly relevant for clinical practice. Frailty education can be delivered successfully in a virtual setting. Junior doctors prefer interactive case based learning, with use of breakout rooms with small numbers of participants in each room.

Matched FES and FDG PET imaging in patients with hormone receptor-positive, HER2+ advanced breast cancer

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Background: The recently FDA approved 18F-Fluoroestradiol (FES) is a PET imaging tracer for characterizing disease in patients with ER+ breast cancer. As FES PET enters clinical practice it will be important to establish its utility in the full population of hormone-receptor positive patients, including those with HER2+ tumors. Historically the consensus around ER+/HER+ disease has been that these tumors are primarily driven by HER2, with therapies focused on targeting this pathway. Emerging research suggests that ER+ and HER2+ tumors represent a distinct phenotype, with bidirectional crosstalk between ER and HER2 pathways contributing to resistance to therapies targeting these critical pathways. Methods: Our cross-sectional database of patients with one or more FES scans stretches back to 1996. We selected all patients with HER2+ advanced breast cancer to determine whether ER is functional in the ER+/HER2+ subset. We examined paired FDG and FES scans and recorded SUVmax in matched lesions between the FDG and FES scans. We also looked at a subset of patients who underwent scans at more than one time-points and examined the clinical characteristics of these cases over time. Results: 36 patients with metastatic ER+, HER2+ breast cancer underwent concurrent FDG and FES PET scans between 1996 and 2013. 34 subjects (94%) were female; 32 (89%) were Caucasian, and 4 (11%) were Asian. Eight patients underwent serial scans. A total of 200 metastatic sites were recorded with the majority (67%) being bony lesions. No difference in quantitative FES avidity was observed between soft tissue and osseous sites. Six patients (16%) had negative FES scans despite displaying FDG avid lesions; three patients had at least one negative FES scan on serial scans, and two demonstrated FES-avid lesions with no FDG activity. Average FES SUVmax for positive scans was 3.5, with a range of 0.8 to 10.7. Among eight patients with multiple scans, half had 2 scans, three had 3 scans, and one had 4 scans. In 7/8 patients (88%) FES avidity increased over time even as FDG decreased or stayed stable with treatment; in one, both FES and FDG decreased on follow up scan. Conclusions: In a cohort of ER+, HER2+ patients undergoing FDG and FES PET scans, robust concordance between FDG and FES uptake was observed. FES avidity increased in patients with multiple scans, suggesting that the ER pathway remained active during treatment. The strong FES positivity in many HER2+ patients in this cohort suggests that FES PET could be used to guide patient selection for trials examining deescalated regimens employing a non-chemotherapy partner for HER2-directed therapy or emphasizing more ER-directed therapies such as CDK4/6 inhibitors, which are not currently approved in this population. With the ongoing development of HER2- PET imaging, combination scans could carry the potential for discrimination between sites, possibly serving as a tool to guide biopsy.

NOTCH1 PEST domain variants are responsive to standard of care treatments despite distinct transformative properties in a breast cancer model

Activating variants in the PEST region of NOTCH1 have been associated with aggressive phenotypes in human cancers, including triple-negative breast cancer (TNBC). Previous studies suggested that PEST domain variants in TNBC patients resulted in increased cell proliferation, invasiveness, and decreased overall survival. In this study, we assess the phenotypic transformation of activating NOTCH1 variants and their response to standard of care therapies. AAV-mediated gene targeting was used to isogenically incorporate 3 NOTCH1 variants, including a novel TNBC frameshift variant, in two non-tumorigenic breast epithelial cell lines, MCF10A and hTERT-IMEC. Two different variants at the NOTCH1 A2241 site (A2441fs and A2441T) both demonstrated increased transformative properties when compared to a non-transformative PEST domain variant (S2523L). These phenotypic changes include proliferation, migration, anchorage-independent growth, and MAPK pathway activation. In contrast to previous studies, activating NOTCH1 variants did not display sensitivity to a gamma secretase inhibitor (GSI) or resistance to chemotherapies. This study demonstrates distinct transformative phenotypes are specific to a given variant within NOTCH1 and these phenotypes do not correlate with sensitivities or resistance to chemotherapies or GSIs. Although previous studies have suggested NOTCH1 variants may be prognostic for TNBC, our study does not demonstrate prognostic ability of these variants and suggests further characterization would be required for clinical applications.

Scrapie infection and endogenous retroviral expression in sheep lymphoid tissues

Transmissible spongiform encephalopathies, or prion diseases, are fatal neurodegenerative diseases affecting humans and animals. Although many host tissues express PrPC (essential for prion replication), relatively few cell types accumulate significant levels of infectivity, including neurons and other cell types in the nervous system, and follicular dendritic cells in secondary lymphoid organs. This suggests that tissue or cell-specific receptors or cofactors could play a role in controlling differential susceptibility to infection. Endogenous retroviruses (ERV), the remnants of ancient retroviral integration into the host germline, may represent one such cofactor. We examined the effect of scrapie infection on expression of three ovine ERV families (enJSRV/β1-OERV, γ1-OERV, γ2-OERV) in secondary lymphoid tissues of sheep at different time points following subcutaneous inoculation, using RT-qPCR. These OERVs were constitutively expressed in the prescapular lymph node and spleen of uninfected sheep. However, we were unable to find convincing evidence of specific differential expression of OERV in the same tissues following scrapie infection, in contrast to previous studies of ERV expression in brains of prion-infected mice and macaques. This study is the first to quantify the expression of potentially functional OERV transcripts in sheep lymphoid tissues, opening up interesting questions about the consequences for host immune function.

Abstract PS4-01: Clinical and genomic correlation of a CLIA certified organoid based functional test in breast cancer patients

The goal of precision medicine is to match the right drug to the right patient. However, every individual cancer carries a unique and complex mosaic of genetic and molecular changes making it difficult to identify the right drug based solely on genomic analysis. We developed a CLIA-certified functional drug assay (PARIS® test) for solid tumors which provides an actionable report of tumor derived organoid sensitivities to targeted, endocrine and chemotherapy agents as a tool for clinical therapeutic decisions. Objectives:1.To establish the concordance between organoid drug sensitivity with well-known genomic or immunohistochemical IHC biomarkers 2.To correlate organoid drug sensitivity with clinical outcomes.Methods: From 2015 to 2020, organoids from 410 tumor samples were subjected to functional testing at SEngine Precision Medicine, including 61 breast tumor samples from 48 patients. Fresh samples of tumor cells from core biopsies, surgical excisions, or from fluids arrived <48 hrs following collection and were cultured as 3D organoids. Samples were evaluated using a multi-dose drug response format with a library of up to 130 oncology drugs. Drug sensitivity was quantified using the SPM score (1-15) that combines sensitivity and personalization of each patient’s response relative to a reference population. Known genomic anchors and IHC subtypes were compared to drug sensitivity to determine concordance.Results: 61 breast cancer samples from 48 patients were analyzed. The median age of patients was 53.4 (r26-76). 65 drugs on average were tested per patient with a mean turnaround time of 21 days (r9 -37). A mean of 6 drugs per patient were identified as top scoring sensitive drugs. In 42 patients with genomic or IHC data, we found high concordance of drug sensitivity with known biomarkers (e.g., HER2+ or ERBB2 amplification:HER2 or EGFR inhibitor, BRCA1 mutation: PARP inhibitor, FGFR1-2 mutation or amplification: FGFR inhibitor, PIK3CA mutation:PI3K inhibitor), measured as sensitivity to the cognate targeted drugs. For PIK3CAmut we found an 80% correlation of organoid sensitivity to alpelisib and taselisib. For HER2/ EGFRinh the correlation was 100%. We also found organoid sensitivity to targeted agents in the absence of known genomic or IHC biomarkers, for example tamoxifen and fulvestrant sensitivity in triple negative breast tumors, or HER2 inhibitor sensitivity in HER2 IHC negative tumors or PARP inhibitor sensitivity with BRCA2 variant of unknown significance (VUS). In a cohort of 18 analyzable patients, the retrospective and prospective correlation between organoid based drug sensitivity and clinical outcome was >90%.Conclusions: Organoid based drug testing exhibits strong concordance with genomic or IHC biomarkers and clinical response. In addition, functional testing identifies candidate therapies in patients lacking biomarkers and can nominate variants of unknown significance as candidate biomarkers. This study highlights the utility of functional assays to support clinical decision making in a genetically heterogenous cancer such as breast cancer.

Citation Format: Astrid Margossian, Anne Richardson, Madison Pollastro, Michael Churchill, Franz Schaub, Shalini Pereira, Payel Chatterjee, Rachele Rosati, Lauren Appleyard, Grace Durenberger, Alex Federation, G. Adam Whitney, Hallie Swan, Trevor Ainge, Robert Diaz, Natasha Hunter, Eric Gamboa, Chris Kemp, Vijayakrishna Gadi, Carla Grandori. Clinical and genomic correlation of a CLIA certified organoid based functional test in breast cancer patients [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 PS4-01.

Abstract OT-13-08: A remote-directed “virtual” clinical trial in metastatic breast cancer to determine feasibility of evaluating patient response to immunotherapy using spliceosome mutational markers (SF3B1): The PRISMM trial (NCT04447651)

Background:

Next-generation sequencing (NGS) is becoming increasingly routine in patients with advanced cancers, and rare mutations may occasionally be identified. Evaluating the efficacy of targeting rare mutations is challenging given the low observed frequencies, which can result in slow accrual to clinical trials. The internet and social media have revolutionized the way we receive information and connect with each other, and may potentially be leveraged to identify patients with rare mutations. Spliceosome mutations, such as SF3B1, occur in approximately 4% of breast cancers. The Park Lab has demonstrated that somatic cell knock-in of an SF3B1 hotspot mutation results in new mRNA transcripts can be translated into aberrant proteins. These preliminary data suggest that spliceosome mutations could produce a high number of neoantigens, which may increase sensitivity to immune checkpoint inhibitors (ICI). Indeed, since response rates to immunotherapy in patients with metastatic breast cancer is low, identifying biomarkers predictive of response is critical. We therefore designed a remotely directed “virtual” clinical trial to determine the feasibility of evaluating Patient Response to Immunotherapy using Spliceosome Mutational Markers (PRISMM, NCT04447651). Methods: The is a prospective feasibility trial in which patients will be identified via a social media campaign that directs potential participants to a landing page where they can fill out an online form. Patients will need to self-identify as having metastatic breast cancer (any receptor status) with an SF3B1 mutation (main eligibility criteria); once this information is confirmed by the study team, outside records will be obtained and their case will be reviewed at an institutional Molecular Tumor Board; ICI may be recommended or not. Recommendations from the Board will be provided to the patient and local oncologist, who will then decide whether to proceed with the Board’s recommendation or not. Efficacy of next line therapy will be followed by physician and patient questionnaires every one to three months. During routine blood collection, we will evaluate plasma tumor DNA (ptDNA) and peripheral blood mononuclear cells (PBMCs) at baseline and three months. The primary objective of this study is to evaluate the feasibility of conducting a prospective study using online recruitment tools, and the feasibility of real-time case review by a centralized Molecular Tumor Board to assist in therapeutic decision making. Secondary objectives include evaluating the clinical effect of ICI including progression-free and overall survival, correlate SF3B1 mutations in ptDNA with tissue-based NGS, and describe immunopharmacodynamic changes by PBMC evaluation. We anticipate screening approximately 5000 patients via our social media campaign to identify 60 eligible patients. We will conduct efficacy interim analysis after 23, 35, 47, and 56 patients are enrolled. The response rate of 1% 5%, 10%, and 20% correspond to 99.8%, 74.7%, 24.9%, and 1.1% chance that the study will stop early with an average sample size of 26.2, 41.3, 53.6, and 58.7 patients enrolled and treated respectively. If the true response rate exceeds 15% the Board will continue to make recommendation for ICI in patients with SF3B1 mutations. For more information please contact us at PRISMM@jhmi.edu.

Citation Format: Natasha Hunter, Jeffrey Wang, Leslie Cope, Christine Hodgdon, Vered Stearns, Elizabeth Jaffee, Ben Park, Cesar A Santa-Maria. A remote-directed “virtual” clinical trial in metastatic breast cancer to determine feasibility of evaluating patient response to immunotherapy using spliceosome mutational markers (SF3B1): The PRISMM trial (NCT04447651) [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-13-08.

Resource-Stratified Guideline-Based Cancer Care Should Be a Priority: Historical Context and Examples of Success

Low- and middle-income countries (LMICs) are shouldering most of the burden of the rapidly increasing cancer incidence and mortality worldwide, and this situation is projected to worsen in coming decades. Studies estimate that more than one million deaths could be prevented annually if all patients received high-quality care, but most LMICs lack the resources and infrastructure to adopt U.S. or European clinical oncology practice guidelines. Several organizations have developed resource-stratified guidelines (RSGs) to provide graduated and/or region-specific strategies for cancer diagnosis and treatment. The birth of these efforts traces to 2002, when the World Health Organization (WHO) called for tailoring cancer treatments to the level of available resources by country; the Breast Health Global Initiative (BHGI) formalized the first stratified guidelines for breast cancer shortly thereafter. Since then, multiple organizations including ASCO and the National Comprehensive Cancer Network (NCCN) have created guidelines customized for various cancer subtypes and regions. These RSGs offer roadmaps for policy makers, clinicians, and health care administrators in LMICs to design projects in implementation science that can gradually and strategically raise the quality of cancer care in their nation or region. Although the same resource limitations that complicate cancer care in these areas also pose barriers to data gathering and research, some countries have met the challenge and are improving cancer care using RSGs as a metric for success.

Undetectable Tumor Cell-Free DNA in a Patient With Metastatic Breast Cancer With Complete Response and Long-Term Remission

The ability to serially monitor tumor-derived cell-free DNA (cfDNA) brings with it the potential to measure response to anticancer therapies and detect minimal residual disease (MRD). This report describes a patient with HER2-positive metastatic breast cancer with an exceptional response to trastuzumab and nab-paclitaxel who remains in complete remission several years after cessation of therapy. Next-generation sequencing of the patient's primary tumor tissue showed several mutations, including an oncogenic hotspot PIK3CA mutation. A sample of cfDNA was collected 6 years after her last therapy and then analyzed for mutant PIK3CA using digital PCR. No detectable mutations associated with the primary tumor were found despite assaying >10,000 genome equivalents, suggesting that the patient had achieved a molecular remission. Results of this case study suggest that serial monitoring of MRD using liquid biopsies could provide a useful method for individualizing treatment plans for patients with metastatic disease with extreme responses to therapy. However, large-scale clinical studies are needed to validate and implement these techniques for patient care.

Abstract P6-10-05: TBCRC 040: Pathologic response evaluation and detection in circulating tumor DNA (PREDICT DNA): Initial results piloting a tissue-biopsy independent method of identifying and monitoring tumor-specific mutations in early stage breast cancer

Introduction: The PREDICT DNA trial is the first prospective, multi-center study aimed at validating cell-free plasma derived circulating tumor DNA (ctDNA) as a biomarker for treatment response and recurrence in early stage, triple-negative or HER2-positive (any hormone receptor status) breast cancer. Its primary aim is to determine the negative predictive value (NPV) of the absence of ctDNA after neoadjuvant therapy (NAT) for the achievement of pathologic complete response (pCR). This study has met its accrual goals and results of the overall trial are anticipated within the next year. The initial PREDICT DNA study design stipulated that tumor specific mutations (TSMs) to be tracked in blood would be identified by next gen sequencing (NGS) of tumor biopsy tissue. A disadvantage of this design is the dependence on adequate biopsy tissue. Recently, the advent of Safe-SeqS technology has enabled robust detection of rare variants using NGS with a sensitivity of approximately 0.05% mutant allele fraction. We employed these new NGS methods to pilot a novel tissue-independent approach to ctDNA detection and monitoring. Objective: The primary objective of this pilot study was to determine whether ultrasensitive NGS using a targeted cancer mutation panel can identify TSMs in ctDNA of early-stage breast cancer patients without the use of biopsy tissue. Methods: The PREDICT DNA trial enrolled 228 women from 22 sites with stage II/III breast cancer for whom standard neoadjuvant therapy was planned. Of these, 58 patients had matched pre-and post-NAT samples available for analysis at the time of this pilot. All pre-NAT samples were analyzed for the presence of TSMs using Sysmex Inostics’ SafeSEQ. Patients with detectable ctDNA before NAT were also evaluated for residual ctDNA after completion of NAT but prior to surgery. Five samples were also tested by digital PCR (BEAMing) for cross-platform comparison. Results: TSMs in ctDNA were identified in 29 of 58 patients (50%) prior to NAT. Of pre-NAT ctDNA(+) patients, TSMs were detected in TP53 (90%) and PIK3CA (10%); three patients (10%) were found to have 2 TSMs. Concordance between SafeSEQ and BEAMing was 100% in five samples tested [3 ctDNA(+), 2 ctDNA(-)]. Of 29 ctDNA(+) patients, 24 (83%) demonstrated reduction or elimination of detectable ctDNA following neoadjuvant therapy, with 16 (55%) converting to ctDNA(-). Conclusion: Identification of TSMs in the plasma of early-stage breast cancer patients without the need for biopsy tissue is feasible using a SafeSEQ cancer mutation panel. Further measures to improve the sensitivity of pre-treatment TSM analysis, such as increased plasma volume input and comprehensive TP53 mutational analysis are currently under investigation. Correlations between clinicopathologic factors with ctDNA detection and burden, as well as the NPV of post-NAT ctDNA for pCR and residual cancer burden, will be reported at the time of abstract presentation.

NH and HP contributed equally to this work.

Citation Format: Natasha Hunter, Heather Parsons, Alexander Sherry, Daniel Shinn, Dong Ho Shin, Alex Cole, Giovanni Cragnotti, Taylor Groginski, Margaret Leathers, Andrea L Richardson, Pedram Argani, Antonio Wolff, Leslie Cope, Dan Edelstein, Frank Holtrup, Hilary Sloane, Bapsi Chakravarthy, Vered Stearns, Ben H Park. TBCRC 040: Pathologic response evaluation and detection in circulating tumor DNA (PREDICT DNA): Initial results piloting a tissue-biopsy independent method of identifying and monitoring tumor-specific mutations in early stage 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 P6-10-05.

TrkA overexpression in non-tumorigenic human breast cell lines confers oncogenic and metastatic properties

BACKGROUND/PURPOSE

TrkA overexpression occurs in over 20% of breast cancers, including triple-negative breast cancers (TNBC), and has recently been recognized as a potential driver of carcinogenesis. Recent clinical trials of pan-Trk inhibitors have demonstrated targeted activity against tumors harboring NTRK fusions, a relatively rare alteration across human cancers. Despite this success, current clinical trials have not investigated TrkA overexpression as an additional therapeutic target for pan-Trk inhibitors. Here, we evaluate the cancerous phenotypes of TrkA overexpression relative to NTRK1 fusions in human cells and assess response to pharmacologic Trk inhibition.

EXPERIMENTAL DESIGN/METHODS

To evaluate the clinical utility of TrkA overexpression, a panel of TrkA overexpressing cells were developed via stable transfection of an NTRK1 vector into the non-tumorigenic breast cell lines, MCF10A and hTERT-IMEC. A panel of positive controls was generated via stable transfection with a CD74-NTRK1 fusion vector into MCF10A cells. Cells were assessed via various in vitro and in vivo analyses to determine the transformative potential and targetability of TrkA overexpression.

RESULTS

TrkA overexpressing cells demonstrated transformative phenotypes similar to Trk fusions, indicating increased oncogenic potential. TrkA overexpressing cells demonstrated growth factor-independent proliferation, increased PI3Kinase and MAPKinase pathway activation, anchorage-independent growth, and increased migratory capacity. These phenotypes were abrogated by the addition of the pan-Trk inhibitor, larotrectinib. In vivo analysis demonstrated increased tumorgenicity and metastatic potential of TrkA overexpressing breast cancer cells.

CONCLUSIONS

Herein, we demonstrate TrkA overexpressing cells show increased tumorgenicity and are sensitive to pan-Trk inhibitors. These data suggest that TrkA overexpression may be an additional target for pan-Trk inhibitors and provide a targeted therapy for breast cancer patients.

Abstract P4-01-16: Detection of plasma tumor DNA (ptDNA) in patients with hormone receptor-positive HER2-negative (HR+HER2-) early breast cancer (EBC) in clinical remission

Background: Detection of ptDNA in patients with HR+HER2- EBC in clinical remission may impact recommendations for type and duration of adjuvant endocrine therapy. A sensitive technique to identify tumor mutations in plasma is BEAMing digital PCR. The frequency and timing of detectable mutations in plasma of patients in clinical remission from HR+HER2- EBC are unknown.

Methods: We screened a prospective institutional repository for patients that met inclusion criteria. Eligible patients must have been enrolled to the repository between 12/1/2008 (repository start) and 12/31/2016, had HR+HER2- EBC, received follow-up at Johns Hopkins with appointment scheduled between 3/1/2017 and 12/31/2017, completed curative surgery at least 6 months prior to this appointment, been recommended or initiated adjuvant endocrine therapy, and been in clinical remission. Appropriate patients were approached for a current blood sample during their follow-up appointment in 2017. Blood was analyzed using a BEAMing digital PCR platform (Sysmex Inostics OncoBEAM™) for AKT1, PIK3CA, and ESR1 mutations.

Results: We identified 67 eligible patients and collected blood from 60. Most patients had relatively low risk disease including 40 patients (67%) with stage I disease, and only 21 patients (35%) received chemotherapy. Patients were evenly divided between receiving tamoxifen or an aromatase inhibitor, and some patients switched from one to the other. The majority of patients (68%) had surgery between 1 and 5 years prior to the current blood draw. Detailed patient characteristics are provided in Table 1.

Two out of the 60 patients had detectable ptDNA, both with stage IIA disease. One patient had a mutation in the ESR1 ligand-binding domain P535H 9 months after surgery and while taking adjuvant tamoxifen for 7 months. Sanger sequencing of primary tumor tissue did not reveal this mutation. Another patient had a mutation in PIK3CA exon 9 E542K 9.5 years after surgery and after taking adjuvant tamoxifen for at least 7 years. Amplifying this locus in DNA from primary tumor tissue was unsuccessful; further analysis using droplet digital PCR (ddPCR) is planned.

Conclusions: Detection of ptDNA was feasible in a relatively low-risk group of patients with HR+HER2- EBC in clinical remission. Sampling a larger number of patients is needed to gain more understanding of the frequency and timing of detectable ptDNA. Next steps should also focus on determining the natural history of detectable ptDNA in patients with HR+HER2 EBC in clinical remission which may impact adjuvant treatment recommendations.

Funding sources: Komen SAC110053, P30 CA06973, Breast Cancer Research Foundation

Table 1:Characteristics of included patients N (%)Total patients60Age at diagnosis, median(range)57 (30-77)Female59 (98)Caucasian54 (90)Postmenopausal at diagnosis36 (60)Tumor size <2 cm42 (70)Node negative45 (75)Invasive ductal histology44 (73)Received adjuvant chemotherapy21 (35)Type of adjuvant endocrine therapy Tamoxifen25 (42)Aromatase inhibitor26 (43)Tamoxifen and AI7 (12)None2 (3)Time after surgery 6 months to <1 year6 (10)1 year to <5 years41 (68)5 years to <10 years13 (22)

Citation Format: Shah M, Hunter N, Ensminger J, Shinn D, Cole AJ, Quinn HE, Edelstein DL, Wang C, Smith KL, Richardson AL, Cimino-Mathews A, Wolff AC, Cravero K, Park BH, Stearns V. Detection of plasma tumor DNA (ptDNA) in patients with hormone receptor-positive HER2-negative (HR+HER2-) early breast cancer (EBC) in clinical remission [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P4-01-16.

Biotinylated amplicon sequencing: A method for preserving DNA samples of limited quantity

Background

Genomic testing is often limited by the exhaustible nature of human tissue and blood samples. Here we describe biotinylated amplicon sequencing (BAmSeq), a method that allows for the creation of PCR amplicon based next-generation sequencing (NGS) libraries while retaining the original source DNA.

Design and methods

Biotinylated primers for different loci were designed to create NGS libraries using human genomic DNA from cell lines, plasma, and formalin-fixed paraffin embedded (FFPE) tissues using the BAmSeq protocol. DNA from the original template used for each BAmSeq library was recovered after separation with streptavidin magnetic beads. The recovered DNA was then used for end-point, quantitative and droplet digital PCR (ddPCR) as well as NGS using a cancer gene panel.

Results

Recovered DNA was analyzed and compared to the original DNA after one or two rounds of BAmSeq. Recovered DNA revealed comparable genomic distributions and mutational allelic frequencies when compared to original source DNA. Sufficient quantities of recovered DNA after BAmSeq were obtained, allowing for additional downstream applications.

Conclusions

We demonstrate that BAmSeq allows original DNA template to be recovered with comparable quality and quantity to the source DNA. This recovered DNA is suitable for many downstream applications and may prevent sample exhaustion, especially when DNA quantity or source material is limiting.

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Modification of targeted panel sequencing allows for recovery of original DNA template.

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Protocol provides value in the setting of scarce DNA template.

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Recovered DNA is suitable for NGS, ddPCR and qPCR.

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Recovered DNA shows no loss of genomic regions.

Abstract 1408: SF3B1 mutations induce proteome remodeling, metabolic reprogramming, and a novel kind of tumor surface antigen in human cells

Mutations in the SF3B1 gene occur in multiple cancers, creating a neomorphic spliceosome protein that induces aberrant mRNA splicing in thousands of genes. Little is known about the downstream oncogenic or therapeutic consequences of this missplicing. To study this, we engineered knockins of SF3B1 mutation in untransformed breast epithelial cells, as well as “reverse” knockins in which SF3B1-mutant uveal melanoma cells were corrected to wild type. Transcriptomic analysis of these isogenic pairs showed cryptic splicing induced by mutant SF3B1, and SILAC proteomics demonstrated a broad reshaping of the proteome dominated by downregulation of misspliced genes. Interestingly, pathway analysis revealed a suppression of proteins involved in energy metabolism. This included mitochondrial complex III, which rescue experiments showed was downregulated through missplicing of its assembly factor UQCC1, and PHGDH, a serine synthesis enzyme likewise misspliced and downregulated. Metabolomic analysis also showed evidence of metabolic reprogramming by mutant SF3B1, including suppression of serine, glycine, and aspartate levels. Because serine and glycine (SG) starvation can have anticancer activity in vivo—and because PHGDH expression modulates this effect—we tested SG starvation on SF3B1-mutant cells. Growth of our SF3B1-mutant isogenic cells was differentially suppressed by SG starvation, and two independent AML cell lines with endogenous SF3B1 mutation demonstrated significant cell death upon SG starvation, in contrast to multiple AML cell lines wild type for SF3B1. These data suggest impaired serine synthesis may be a therapeutic vulnerability in SF3B1-mutant cancers. In addition to downregulation of genes induced by mutant SF3B1, our proteomic data also revealed a novel cryptic protein that was highly enriched in SF3B1-mutant cells. This protein, CD98, is a surface membrane protein, and the cryptic peptide change occurred in its extracellular domain. Additional transcriptome analysis revealed eleven more candidate surface proteins with mutant SF3B1-induced cryptic isoforms containing in-frame peptide changes in extracellular domains, and overexpression studies demonstrated at least two of these cryptic proteins can traffic to the cell surface. We have named these putative proteins MASAs, for Missplicing-Associated Surface Antigens, and we believe they represent a novel kind of tumor surface antigen that may be targetable with antibody-based immunotherapeutics. In summary, our data provide evidence that SF3B1 mutations induce proteome alterations, metabolic reprogramming, and a new kind of tumor surface antigen in human cells.

Citation Format: William B. Dalton, Daniel Shinn, Noel Walsh, Eric Christenson, Taylor Groginski, Dhanashree Kelkar, Anil Magugundu, Arun Patil, Daniel Zabransky, Arielle Medford, Justin Lee, Alex Cole, Josh Donaldson, Amy DeZern, Karen Cravero, David Chu, Natasha Hunter, Akhilesh Pandey, Josh Lauring, Ben Park. SF3B1 mutations induce proteome remodeling, metabolic reprogramming, and a novel kind of tumor surface antigen in human cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1408.

Protecting effect of PrP codons M142 and K222 in goats orally challenged with bovine spongiform encephalopathy prions

Breeding towards genetic resistance to prion disease is effective in eliminating scrapie. In sheep, classical forms of scrapie have been eradicated almost completely in several countries by breeding programs using a prion protein (PrP) gene (PRNP) amino acid polymorphism. For goats, field and experimental studies have provided evidence for several amino acid polymorphisms that are associated with resistance to scrapie, but only limited data are available concerning the susceptibility of caprine PRNP genotypes to BSE. In this study, goat kids representing five PRNP genotypes based on three polymorphisms (M142, Q211 and K222 and the wild type I142, R211 and Q222) were orally challenged with bovine or goat BSE. Wild type goats were killed with clinical signs between 24-28 months post inoculation (mpi) to both challenges, and goats with genotype R/Q211 succumbed between 29-36 mpi. I/M142 goats developed clinical signs at 44-45 mpi and M/M142 goats remained healthy until euthanasia at 48 mpi. None of the Q/K222 goats showed definite clinical signs. Taken together the highest attack ratios were seen in wild type and R/Q211 goats, and the lowest in I/M142, M/M142 and Q/K222. In all genotype groups, one or more goats remained healthy within the incubation period in both challenges and without detectable PrP deposition in the tissues. Our data show that both the K222 and M142 polymorphisms lengthen the incubation period significantly compared to wild type animals, but only K222 was associated with a significant increase in resistance to BSE infection after oral exposure to both BSE sources.

Altered trafficking of abnormal prion protein in atypical scrapie: prion protein accumulation in oligodendroglial inner mesaxons

AIMS

Prion diseases exist in classical and atypical disease forms. Both forms are characterized by disease-associated accumulation of a host membrane sialoglycoprotein known as prion protein (PrPd ). In classical forms of prion diseases, PrPd can accumulate in the extracellular space as fibrillar amyloid, intracellularly within lysosomes, but mainly on membranes in association with unique and characteristic membrane pathology. These membrane changes are found in all species and strains of classical prion diseases and consist of spiral, branched and clathrin-coated membrane invaginations on dendrites. Atypical prion diseases have been described in ruminants and man and have distinct biological, biochemical and pathological properties when compared to classical disease. The purpose of this study was to determine whether the subcellular pattern of PrPd accumulation and membrane changes in atypical scrapie were the same as those found in classical prion diseases.

METHODS

Immunogold electron microscopy was used to examine brains of atypical scrapie-affected sheep and Tg338 mice.

RESULTS

Classical prion disease-associated membrane lesions were not found in atypical scrapie-affected sheep, however, white matter PrPd accumulation was localized mainly to the inner mesaxon and paranodal cytoplasm of oligodendroglia. Similar lesions were found in myelinated axons of atypical scrapie Tg338-infected mice. However, Tg338 mice also showed the unique grey matter membrane changes seen in classical forms of disease.

CONCLUSIONS

These data show that atypical scrapie infection directs a change in trafficking of abnormal PrP to axons and oligodendroglia and that the resulting pathology is an interaction between the agent strain and host genotype.

[Risk of death from circulatory diseases in a cohort of patients exposed to chronic radiation]

AIM

To assess mortality from circulatory diseases (CD) in a cohort of workers exposed occupationally to chronic radiation in relation to external and internal exposure, by taking into account known non-radiation risk factors (RFs), such as smoking (including smoking index), alcohol consumption, hypertension, and body mass index.

SUBJECTS AND METHODS

Mortality from CD (ICD-10: I00 - I99) was studied in a cohort of 22,377 nuclear power plant («Mayak» Production Association) workers exposed occupationally to chronic radiation. The study was based on the individual dose estimates of external and internal exposure taken from the new Mayak workers dosimetry system 2008 (MWDS-2008). The quantitative characteristics of smoking (smoking index) were used for the first time to assess the risk for CD in the cohort of workers exposed to chronic radiation.

RESULTS

There was a statistically significant linear relationship between CD mortality and external gamma-dose after adjusting for the non-radiation RFs; the excess relative risk per unit dose (ERR/Gy) was 0.05 (95% confidence interval (CI): 0 to 0.11). Introducing an additional adjustment for internal alpha-dose resulted in a twofold increase in ERR/Gy=0.10 (95% CI: 0.02 to 0.21). There was a statistically significant increasing trend in CD mortality with the elevated absorbed dose from internal alpha-radiation in the liver (ERR/Gy=0.27; 95% CI: 0.12 to 0.48). However, ERR/Gy decreased and lost its statistical significance after adjusting for external gamma-dose.

CONCLUSION

The results of this study are in good agreement with risk estimates obtained in the Japanese cohort of atomic bomb survivors and in the cohorts of occupationally exposed workers.

Long term variations in erythema effective solar UV at Chilton, UK, from 1991 to 2015

This publication presents an analysis of 25 years (1991–2015) of erythema effective UV radiant exposure data measured at Chilton, UK which is part of Public Health England's solar network.

Risk of mortality from circulatory diseases in Mayak workers cohort following occupational radiation exposure

Mortality from circulatory diseases (CD) (ICD-9 codes 390-459) was studied in an extended Mayak worker cohort, which included 22,377 workers first employed at the Mayak Production Association in 1948-1982 and followed up to the end of 2008. The enlarged cohort and extended follow-up as compared to the previous analyses provided an increased number of deaths from CD and improved statistical power of this mortality study. The analyses were based on dose estimates provided by a new Mayak Worker Dosimetry System 2008 (MWDS-2008). For the first time in the study of non-cancer effects in this cohort quantitative smoking data (smoking index) were taken into account. A significant increasing trend for CD mortality with increasing dose from external gamma-rays was found after having adjusted for non-radiation factors; the excess relative risk per unit dose (ERR/Gy) was 0.05 (95% confidence interval (CI):  >0, 0.11). Inclusion of an additional adjustment for dose from internal alpha-radiation to the liver resulted in a two-fold increase of ERR/Gy = 0.10 (95% CI: 0.02, 0.21). A significant increasing trend in CD mortality with increasing dose from internal alpha-radiation to the liver was observed (ERR/Gy = 0.27, 95% CI: 0.12, 0.48). However the ERR/Gy decreased and lost its significance after adjusting for dose from external gamma-rays. Results of the current study are in good agreement with risk estimates obtained for the Japanese LSS cohort as well as other studies of cohorts of nuclear workers.

Hepatocellular carcinoma and end-of-life care

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Background: Patients with hepatocellular carcinoma (HCC) usually present with incurable tumors and advanced underlying liver disease. Although guidelines exist to assess the quality of end of life (EOL) care for cancer patients, little is known about EOL care for HCC patients. Due to the complexity and multidisciplinary nature of the disease, we hypothesized that EOL care for HCC patients differs from that delivered to other cancer patients and may be heterogenous based on patient characteristics and primary clinician specialty. Methods: We assessed EOL HCC care through medical chart review of 188 consecutive HCC patients treated at an academic tertiary care hospital who died between 2007 and 2013. Based on available data, EOL care and documentation was assessed per published guidelines. Patient, HCC and liver disease characteristics, cancer treatments, symptom burden, and EOL care and documentation was compared by provider specialty. The odds of receiving aggressive EOL care by provider specialty, patient characteristics, and documentation measures were calculated. Using data from the Dartmouth Atlas Project, we compared results with EOL data for cancer patients overall at our institution and nationally during a similar time frame. Results: Fewer HCC patients enrolled in hospice compared with cancer patients overall at our institution, and nationally (36%, 49% and 55%, respectively). In addition, HCC patients spent fewer days on hospice, spent more time in the hospital, and experienced more (and longer) intensive care unit admissions. Compared to those primarily cared for by other specialties, HCC patients seen by an oncologist were more likely to have goals of care (GOC) documentation and to enroll in hospice. Patients never seen by an oncologist were more likely to have a psychiatric illness. English as a non-primary language and code status documentation were among factors associated with more aggressive EOL care. Conclusions: At our institution, EOL care for HCC patients is more aggressive compared to cancer patients overall and nationally. The subset of HCC patients seen by oncology were more likely to meet EOL quality guidelines (GOC documentation and hospice enrollment). A better understanding of EOL practices for HCC may impact multidisciplinary care.

Chronic bronchitis in the cohort of Mayak workers first employed 1948-1958

Incidence of chronic bronchitis has been studied in a cohort of 12,210 workers first employed at one of the main plants of the Mayak nuclear facility during 1948-1958 and followed up to 31 December 2005. Information on external gamma doses is available for virtually all of these workers; in contrast, plutonium body burden was measured only for 30% of workers. During the follow-up period in the study cohort 1,175 incident cases of chronic bronchitis were verified. The analyses of nonradiation factors revealed that the underlying risk of chronic bronchitis incidence increased with increasing attained age and was higher among smokers compared with never-smokers as would be expected. The most interesting finding in relationship to nonradiation factors was a sharp increase in the baseline chronic bronchitis risk before 1960. The cause of this is not clear but a number of factors may play a role. Based on the follow-up data after 1960, the analysis showed a statistically significant linear dose response relationship with cumulative external gamma-ray dose (ERR/Gy = 0.14, 95% CI 0.01, 0.32). Based on the same subset but with an additional restriction to members with cumulative internal lung dose below 1 Gy, a statistically significant linear dose response relationship with internal alpha-radiation lung dose from incorporated plutonium was found (ERR/Gy = 2.70, 95% CI 1.20, 4.87). In both cases, adjustment was made for nonradiation factors, including smoking and either internal or external dose as appropriate. At present there are no similar incidence studies with which to compare results. However, the most recent data from the atomic bomb survivor cohort (the Life Span Study) showed statistically significant excess mortality risk for respiratory diseases of 22% per Gy and this value is within the confidence bounds of the point estimate of the risk from this study in relation to external dose.

Solid cancer incidence other than lung, liver and bone in Mayak workers: 1948-2004

BACKGROUND

Cancer incidence in the Mayak Production Association (PA) cohort was analysed to investigate for the first time whether external gamma-ray and internal plutonium exposure are associated with raised incidence of solid cancers other than lung, liver and bone (other solid cancers).

METHODS

The cohort includes 22,366 workers of both sexes who were first employed between 1948 and 1982. A total of 1447 cases of other solid cancers were registered in the follow-up period until 2004. The Poisson regression was used to estimate the excess relative risk (ERR) per unit of cumulative exposure to plutonium and external gamma-ray.

RESULTS

A weak association was found between cumulative exposure to external gamma-ray and the incidence of other solid cancers (ERR/Gy=0.07; 95% confidence intervals (CIs): 0.01-0.15), but this association lost its significance after adjusting for internal plutonium exposure. There was no indication of any association with plutonium exposure for other solid cancers. Among 16 individual cancer sites, there was a statistically significant association with external exposure for lip cancer (ERR/Gy=1.74; 95% CI: 0.37; 6.71) and with plutonium exposure for pancreatic cancer (ERR/Gy=1.58; 95% CI; 0.17; 4.77).

CONCLUSION

This study of Mayak workers does not provide evidence of an increased risk of other solid cancers. The observed increase in the risk of cancer of the lip and pancreas should be treated with caution because of the limited amount of relevant data and because the observations may be simply due to chance.

The lysine gingipain adhesin domains from Porphyromonas gingivalis interact with erythrocytes and albumin: Structures correlate to function

The crystal structure of the K1 domain, an adhesin module of the lysine gingipain (Kgp) expressed on the cell surface by the periodontopathic anaerobic bacterium, Porphyromonas gingivalis W83, is compared to the previously determined structures of homologues K2 and K3, all three being representative members of the cleaved adhesin domain family. In the structure of K1, the conformation of the most extensive surface loop is unexpectedly perturbed, perhaps by crystal packing, and is displaced from a previously reported arginine-anchored position observed in K2 and K3. This displacement allows the loop to become free to interact with other proteins; the alternate flipped-out loop conformation is a novel mechanism for interacting with target host proteins, other bacteria, or other gingipain protein domains. Further, the K1 adhesin module, like others, is found to be haemolytic in vitro, and so, functions in erythrocyte recognition thereby contributing to the haemolytic function of Kgp. K1 was also observed to selectively bind to haem-albumin with high affinity, suggesting this domain may be involved in gingipain-mediated haem acquisition from haem-albumin. Therefore, it is most likely that all cleaved adhesin domains of Kgp contribute to the pathogenicity of P. gingivalis in more complex ways than simply mediating bacterial adherence.

Radiation risk of malignant neoplasms in organs of main deposition for plutonium in the cohort of Mayak workers with regard to histological types

This paper presents the results of analyses of the incidence of malignant neoplasms in lung, liver, and bone and associated connective tissues among Mayak nuclear workers exposed to both internally incorporated plutonium and to external gamma radiation. The study cohort included 22,373 individuals employed at the reactors and radiochemical and plutonium production facilities of the Mayak nuclear complex during 1948-1982 and followed up to the end of 2004. All analyses were carried out by Poisson regression, and the doses used were derived using a recently available update of organ doses, Mayak doses-2008. There was clear evidence for the linear association between internal plutonium dose and the risk of lung cancer. For males, there was evidence of a significant internal plutonium dose response for all histological types of lung cancer evaluated (adenocarcinoma, squamous-cell, and other epithelial); the estimated excess relative risk (ERR)/Gy for adenocarcinoma was the largest (ERR/Gy = 32.5; 95% CI: 16.3; 71.9), about 11-fold higher than that for squamous-cell lung cancer (ERR/Gy = 3.1; 95% CI: 0.3; 9.1). The relationship between liver cancer risk and plutonium exposure was best described by a linear-quadratic (LQ) function, but the LQ effect was diminished after restricting internal doses <2 Gy. Hepatocellular cancer was the most frequently observed type of liver cancer associated with internal plutonium exposure, and hemangiosarcomas were exclusively observed only at high internal plutonium doses (>4 Gy). For malignant neoplasms of bone and associated connective tissues, the trend was not statistically significant in relation to internal plutonium dose, but a statistically significantly higher risk (RR=13.7; 95% CI= 3.0; 58.5) was found among unmonitored female plutonium workers who were employed in the most hazardous plutonium production facility commissioned prior to 1950.

Expression patterns of tight junction components induced by CD24 in an oral epithelial cell-culture model correlated to affected periodontal tissues

BACKGROUND AND OBJECTIVE

Previously we demonstrated uniformly strong expression of CD24 in the epithelial attachment to the tooth and in the migrating epithelium of the periodontitis lesion. Titers of serum antibodies autoreactive with CD24 peptide correlated with reduced severity of periodontal disease. Ligation of CD24 expressed by oral epithelial cells induced formation of tight junctions that limited paracellular diffusion. In this study, we aimed to reveal that the lack of uniform expression of tight junction components in the pocket epithelium of periodontitis lesions is likely to contribute to increased paracellular permeability to bacterial products. This is proposed as a potential driver of the immunopathology of periodontitis.

MATERIAL AND METHODS

An epithelial culture model with close correspondence for expression patterns for tight junction components in periodontal epithelia was used. Immunohistochemical staining and confocal laser scanning microscopy were used to analyse patterns of expression of gingival epithelial tight junction components.

RESULTS

The minimally inflamed gingival attachment was characterized by uniformly strong staining at cell contacts for the tight junction components zona occludens-1, zona occludens-2, occludin, junction adhesion molecule-A, claudin-4 and claudin-15. In contrast, the pocket epithelium of the periodontal lesion showed scattered, uneven staining for these components. This pattern correlated closely with that of unstimulated oral epithelial cells in culture. Following ligation of CD24 expressed by these cells, the pattern of tight junction component expression of the minimally inflamed gingival attachment developed rapidly.

CONCLUSION

There was evidence for non-uniform and focal expression only of tight junction components in the pocket epithelium. In the cell-culture model, ligation of CD24 induced a tight junction expression profile equivalent to that observed for the minimally inflamed gingival attachment. Ligation of CD24 expressed by gingival epithelial cells by lectin-like receptors of commensal oral streptococci could mediate the phenotype of health, whereas pathogenic organisms associated with periodontal disease might not signal effectively through CD24.

Factors affecting delay in initiation of treatment of tuberculosis in the Thames Valley, UK

OBJECTIVE

To quantify and determine factors associated with delay in initiation of tuberculosis (TB) treatment in the Thames Valley area, South East England, and the proportion of this delay that could be attributed to patient care-seeking or to delay within the National Health Service (NHS).

STUDY DESIGN

Retrospective analysis study reviewing medical notes and enhanced TB surveillance data.

METHODS

Demographic and clinical information was collected from medical notes and the Enhanced TB Surveillance database for patients who were diagnosed with TB and resident in the Thames Valley. Treatment delay was defined as the period between the onset of symptoms and the start of treatment. Patient delay was defined as the period between the onset of symptoms and the first presentation to the NHS. Health service delay was defined as the period between the first contact with the NHS and the start of treatment. Univariate and multivariate linear regression analyses were used to assess the association between delays and explanatory variables (age, gender, place of birth, ethnicity, disease site, sputum smear, culture, primary care trust of residence).

RESULTS

The study included 273 patients with TB. The median time between symptom onset and initiation of treatment was 73 days [95% confidence interval (CI) 65-89], of which the contributions of health service, patient and referral delays were 39 (95% CI 34-55), 29 (95% CI 22-36) and 16 (95% CI 12-24) days, respectively. On multivariate analysis, extrapulmonary TB (P = 0.010), female (P = 0.003) and UK-born (P = 0.008) patients were associated with longer health service delay. Age (P = 0.001) and extrapulmonary TB (P = 0.010) were associated with longer overall treatment delay.

CONCLUSION

Treatment delay for TB, especially delay after first presentation to the NHS, remains a public health concern. Differences in health service delay, for example by gender and country of birth, highlight that some of this should be open to health service intervention.

Seasonal variation of radon concentrations in UK homes

The patterns of seasonal variation of radon concentrations were measured in 91 homes in five regions of the UK over a period of two years. The results showed that there was no significant difference between the regions in the pattern or magnitude of seasonal variation in radon concentrations. The arithmetic mean variation was found to be close to that found previously in the UK national survey. Differences in the pattern between the two years of the study were not significant. Two-thirds of homes in the study followed the expected pattern of high radon in the winter and low radon in the summer. Most of the rest showed little seasonal variation, and a few showed a reversed seasonal pattern. The study does not provide any clear evidence for the recorded house characteristics having an effect on the seasonal variation in radon concentrations in UK homes, though the statistical power for determining such effects is limited in this study. The magnitude of the seasonal variation varied widely between homes. Analysis of the individual results from the homes showed that because of the wide variation in the amount of seasonal variation, applying seasonal correction factors to the results of three-month measurements can yield only relatively small improvements in the accuracy of estimates of annual mean concentrations.

[Mortality risk of cardiovascular diseases for occupationally exposed workers]

Results of the risk analysis of mortality from ischemic heart disease (IHD) in the cohort of Mayak nuclear workers (18763 individuals) first employed in 1948-1972, with follow-up to 31.12.2005, were summarized. The mortality risk of IHD in the cohort of Mayak workers depended on the non-radiation factors such as gender, age, calendar period, smoking, alcohol consumption, arterial hypertension, body mass index. There was no statistically significant relationship between mortality from 1HD and total external dose. The risk of mortality from IHD was significantly higher for workers exposed to the total absorbed dose to liver > 0.025 Gy from internal alpha-radiation. There was a significantly increasing trend (ERR/Gy) of the IHD mortality with the total absorbed dose to liver from internal alpha-radiation due to incorporated plutonium. However, there was a decreasing trend of ERR/Gy with restriction of the follow-up to Ozyorsk and adjustment for the external dose.

[Risk of cerebrovascular disease incidence in the cohort of Mayak production association workers first employed during 1948-1958]

Incidence of cerebrovascular diseases (CVD) has been studied in a cohort of 12210 workers first employed at one of the main plants (reactors, radiochemical or plutonium) of the Mayak nuclear facility during 1948-1958 and followed up to the end of 2000. Information on external gamma doses is available for virtually all (99.9%) of these workers; the mean (+/- one standard deviation) total gamma dose was 0.91 +/- 0.95 Gy (99% percentile 3.9 Gy) for men and 0.65 +/- 0.75 Gy (99% percentile 2.99 Gy) for women. Plutonium body burden was measured only for 30.0% of workers. Amongst those monitored, the mean (+/- standard deviation) cumulative liver dose from plutonium alpha exposure was 0.40 +/- 1.15 Gy (99% percentile 5.88 Gy) for men and 0.81 +/- 4.60 Gy (99% percentile 15.95 Gy) for women 4418 cases (first diagnosis) of CVD were identified in the studied cohort. A statistically significant increasing trend in CVD incidence with total external gamma dose was revealed after adjustment for non-radiation factors and internal exposure from incorporated plutonium-239. Excess relative risk per Gy was 0.464 (95% confidence interval 0.360-0.567). Incidence of CVD was statistically significantly higher for the workers chronically exposed to external gamma rays at a dose above 1.0 Gy A statistically significant increasing trend in CVD incidence with internal liver dose from plutonium alpha exposure was observed after adjustment for non-radiation factors and external exposure. ERR per Gy was 0.155 (95% confidence interval 0.075-0.235). CVD incidence was statistically significantly higher among workers with a plutonium liver dose above 0.1 Gy, although the trend estimates differed between workers at different plants. The incidence risk estimates for external radiation are generally compatible with estimates from the study of Chernobyl clean-up workers, although the incidence data point to higher risk estimates compared to those from the Japanese A-bomb survivors.

Developing a national collaborative of medical educators who lead clinical skills courses

BACKGROUND

The majority of US medical schools now have pre-clerkship clinical skills (PCCS) courses. Course directors for these often logistically complicated courses may be in different medical specialties and, historically, have had few formal opportunities for communication and collaboration with their counterparts at other institutions. As such, we hypothesized that leaders of PCCS courses would benefit from a national network.

SUMMARY

In this paper, we outline the methodology used to form a national collaborative from grass roots interest. Over three years, a self-identified eleven-person task force with national representation has created an organization for PCCS course directors from US medical schools called Directors Of Clinical Skills courses (DOCS) that meets annually.

CONCLUSIONS

Through iterative presentations at regional and national medical education meetings, we have produced an inventory of educational issues for those developing, administering, and evaluating PCCS courses. Further development of this nascent organization is ongoing. Our process is generalizable.

Interaction networks of lithium and valproate molecular targets reveal a striking enrichment of apoptosis functional clusters and neurotrophin signaling

The overall neurobiological mechanisms by which lithium and valproate stabilize mood in bipolar disorder patients have yet to be fully defined. The therapeutic efficacy and dissimilar chemical structures of these medications suggest that they perturb both shared and disparate cellular processes. To investigate key pathways and functional clusters involved in the global action of lithium and valproate, we generated interaction networks formed by well-supported drug targets. Striking functional similarities emerged. Intersecting nodes in lithium and valproate networks highlighted a strong enrichment of apoptosis clusters and neurotrophin signaling. Other enriched pathways included MAPK, ErbB, insulin, VEGF, Wnt and long-term potentiation indicating a widespread effect of both drugs on diverse signaling systems. MAPK1/3 and AKT1/2 were the most preponderant nodes across pathways suggesting a central role in mediating pathway interactions. The convergence of biological responses unveils a functional signature for lithium and valproate that could be key modulators of their therapeutic efficacy.

Cardiovascular diseases in the cohort of workers first employed at Mayak PA in 1948-1958

Incidence of and mortality from cardiovascular diseases have been studied in a cohort of 12,210 workers first employed at one of the main plants of the Mayak nuclear facility during 1948-1958 and followed up to 31 December 2000. Information on external gamma-ray doses is available for virtually all of these workers (99.9%); the mean total gamma-ray dose (+/-SD) was 0.91 +/- 0.95 Gy (99% percentile 3.9 Gy) for men and 0.65 +/- 0.75 Gy (99% percentile 2.99 Gy) for women. In contrast, plutonium body burden was measured for only 30.0% of workers; among those monitored, the mean cumulative liver dose from plutonium alpha exposure (+/- SD) was 0.40 +/- 1.15 Gy (99% percentile 5.88 Gy) for men and 0.81 +/- 4.60 Gy (99% percentile 15.95 Gy) for women. A total of 3751 cases of ischemic heart disease (IHD), including 683 cases of acute myocardial infarction (AMI), and 1495 IHD deaths, including 338 AMI deaths, were identified in the study cohort during the follow-up period. Having adjusted for non-radiation factors, there were statistically significant increasing trends with both total external gamma-ray dose and internal liver dose in IHD incidence. The trend with internal dose was weaker and was not statistically significant after adjusting for external dose, whereas the external dose trend was little changed after adjusting for internal dose. The trend with external dose in IHD mortality was not statistically significantly greater than zero but was consistent with the corresponding trend in IHD incidence. The estimated trend in IHD mortality with internal dose was lower and was not statistically significant once adjustment was made for external dose. There was a statistically significantly increasing trend in AMI incidence but not AMI incidence with external dose. The risk estimates for IHD in relation to external radiation are generally compatible with those from other large occupational studies and the Japanese A-bomb survivors.

Application of polychromatic µCT for mineral density determination

Accurate assessment of mineral density (MD) provides information critical to the understanding of mineralization processes of calcified tissues, including bones and teeth. High-resolution three-dimensional assessment of the MD of teeth has been demonstrated by relatively inaccessible synchrotron radiation microcomputed tomography (SRµCT). While conventional desktop µCT (CµCT) technology is widely available, polychromatic source and cone-shaped beam geometry confound MD assessment. Recently, considerable attention has been given to optimizing quantitative data from CµCT systems with polychromatic x-ray sources. In this review, we focus on the approaches that minimize inaccuracies arising from beam hardening, in particular, beam filtration during the scan, beam-hardening correction during reconstruction, and mineral density calibration. Filtration along with lowest possible source voltage results in a narrow and near-single-peak spectrum, favoring high contrast and minimal beam-hardening artifacts. More effective beam monochromatization approaches are described. We also examine the significance of beam-hardening correction in determining the accuracy of mineral density estimation. In addition, standards for the calibration of reconstructed grey-scale attenuation values against MD, including K(2)PHO(4) liquid phantom, and polymer-hydroxyapatite (HA) and solid hydroxyapatite (HA) phantoms, are discussed.

Cerebrovascular diseases in the cohort of workers first employed at Mayak PA in 1948-1958

The incidence of and mortality from cerebrovascular diseases (CVD) have been studied in a cohort of 12,210 workers first employed at one of the main plants of the Mayak nuclear facility during 1948-1958 and followed up to 31 December 2000. Information on external γ-ray doses is available for virtually all of these workers (99.9%); the mean total γ-ray dose (± SD) was 0.91 ± 0.95 Gy (99th percentile 3.9 Gy) for men and 0.65 ± 0.75 Gy (99th percentile 2.99 Gy) for women. In contrast, plutonium body burden was measured only for 30.0% of workers; among those monitored, the mean cumulative liver dose from plutonium α-particle exposure (± SD) was 0.40 ± 1.15 Gy (99th percentile 5.88 Gy) for men and 0.81 ± 4.60 Gy (99th percentile 15.95 Gy) for women. A total of 4418 cases of CVD, including 665 cases of stroke, and 753 deaths from CVD, including 404 deaths from stroke, were identified in the study cohort. Having adjusted for non-radiation factors, there were statistically significant increasing trends in CVD incidence but not mortality with both total external γ-ray dose and internal liver dose. Much of the evidence for increased incidence in relation to external dose arose for workers with cumulative doses above 1 Gy. Although the dose response is consistent with linearity, the statistical power to detect non-linearity at external doses below 1 Gy was low. CVD incidence was statistically significantly higher among workers with a plutonium liver dose above 0.1 Gy. There was a statistically significant increasing trend in incidence with increasing internal dose, even after adjusting for external dose, although the trend estimates differed between workers at different plants. The risk estimates for external radiation are generally compatible with those from other large occupational studies, although the incidence data point to higher risk estimates compared to those from the Japanese A-bomb survivors.

Pathological phenotype of sheep scrapie after blood transfusion

Blood transfusion practices have resulted in iatrogenic cases of variant Creutzfeldt-Jakob disease (vCJD) and it is known that sheep blood is also infectious in the pre-clinical stages of natural scrapie and experimentally induced bovine spongiform encephalopathy (BSE). Further investigations have also shown that the pathological phenotype of sheep BSE and human vCJD is maintained after blood transfusion. The present study describes the pathological phenotype, in terms of accumulation of the disease-associated prion protein in brain and lymphoreticular tissues, in sheep receiving blood from donors infected with natural scrapie. The immunohistochemical examinations undertaken showed a degree of phenotypic variability within and between scrapie donors and recipients, which might be attributable to the presence of more than one scrapie strain amongst the donor sheep or to a host adaptation process, or to the interaction of both, rather than to the influence of the route of infection.

Pathogenetical significance of porencephalic lesions associated with intracerebral inoculation of sheep with the bovine spongiform encephalopathy (BSE) agent

Decreased rates of transmission of transmissible spongiform encephalopathies (TSEs) to sheep have been attributed to some polymorphisms of the prion protein (PrP) and to a 'species barrier' on interspecies experiments. In addition, the blood-brain barrier may be a further impediment to TSE neuroinvasion. The intracerebral (I/C) route is generally considered the most efficient for TSE transmission, as it may help to bypass those factors. Therefore, susceptibility of particular species to specific TSE agents is conducted by this route.

AIMS

This study characterizes the traumatic brain lesions associated with the I/C injection of the bovine spongiform encephalopathy agent in sheep, assesses the relevance of such lesions in the outcome of clinical disease and provides insight into the mechanisms of PrP(d) conversion and amplification following I/C challenge.

METHODS

A total of 27 hemibrains have been macroscopically and immunohistochemically examined to investigate the presence of lesions compatible with the needle track and the PrP(d) distribution, respectively.

RESULTS

No residual inoculum was found and the extension and severity of the traumatic brain lesions were unrelated to the clinical outcome. Sheep with PrP(d) accumulation in the brain also showed conspicuous focal aggregates in the porencephalic lesions and in the circumventricular organs. In contrast, sheep without PrP(d) deposits in the brain were also negative in the traumatic lesions.

CONCLUSION

Overall, these findings suggest that the efficiency of the I/C route is due to effective absorption and blood recirculation of infection, rather than to primary amplification at the site of injection.

Differential expression of Prnp and Sprn in scrapie infected sheep also reveals Prnp genotype specific differences

The central role for PrP in the pathogenesis of the transmissible spongiform encephalopathies (TSEs) is illustrated by the resistance of Prnp(0/0) mice to disease and by the inverse association of Prnp gene dosage with incubation period. Understanding the role of PrP(C) in TSEs necessitates knowledge of expression levels of the Prnp gene during the development of disease. SSBP/1 scrapie shows a defined pattern of disease progression and here we show that Prnp and shadow of PrP (Sprn) are differentially expressed in different brain areas and lymphoid tissues. Counter-intuitively we found that there is no positive correlation between expression of Prnp or Sprn and patterns of disease progression. Prnp and Sprn expression levels are both influenced by Prnp genotype; although the scrapie-sensitive VRQ/VRQ sheep did not express the highest level of either. In addition, infection with SSBP/1 scrapie seems to have little effect on either PrP or Shadoo expression levels.

Blockade of protease-activated receptors on T cells correlates with altered proteolysis of CD27 by gingipains of Porphyromonas gingivalis

Cysteine proteinases, termed gingipains, of Porphyromonas gingivalis are able to inactivate a broad range of host proteins involved in cellular responses and have been implicated as key virulence factors in the onset and progression of adult periodontitis. In the present study, the high molecular weight Arg-gingipain, RgpA, produced a time- and concentration-dependent hydrolysis of the tumour necrosis factor (TNF)-alpha receptor family member CD27 on resting T cells. As a consequence of CD27 degradation, a reduction in CD27-ligation dependent co-stimulatory CD40L expression was observed. Concomitantly, RgpA activated the protease-activated receptors (PAR)-1, PAR-2 and PAR-4 and induced CD69 and CD25 expression on T cells, thereby demonstrating T cell activation. The Lys-gingipain Kgp demonstrated a low capacity to degrade CD27 but the ability to affect CD27 expression and biological activity was increased when T cells were pretreated with blocking peptide against PAR-2. CD70, the ligand for CD27 induced on activated B cells, was significantly reduced by RgpA treatment and weakly affected by Kgp. These findings suggest that while RgpA can activate T cells through PARs, the parallel action of direct hydrolysis of membrane CD27 as well as CD70 indicates a potential down-regulatory effect through inhibition of CD27/CD70-mediated cell activation in periodontitis.

Scrapie-associated fibrils, PrP protein and the Sinc gene

Scrapie-associated fibrils (SAF) are disease-specific structures found in extracts of the brains of animals affected with scrapie. These structures are pathological aggregates of a normal host protein called PrP. In collaboration with Konrad Beyreuther (Heidelberg), we have characterized the multiple forms of PrP found in SAF fractions from mouse brain affected by the ME7 strain of scrapie. There is no in vivo N-terminal cleavage of the most abundant forms of PrP. However, N-terminal cleavage of some minor forms of PrP does occur in vivo within a domain of repetitive sequences at sites similar to but distinct from those cut by proteinase K in vitro. We suggest that such covalently modified forms of PrP may be the result of enzymic degradation occurring as a consequence rather than as a cause of disease. We also found a novel, as yet unidentified, amino acid derivative of the arginine residue at position 3 in both hamster and mouse PrP 33-35, which may predispose PrP to form SAF. Carlson and colleagues have discovered a linkage between the PrP gene and the murine gene provisionally called Prn-i which, from the work of Carp and coworkers, appears identical to the Sinc gene. The Sinc gene is the major gene determining the incubation period of all strains of scrapie in mice. We have evidence for a linkage of the PrP gene and Sinc using inbred mice of known Sinc genotype, including VM(Sincp7) and VM(Sincs7) congenic mice. PrP may even be the protein product of the Sinc gene.