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Neoadjuvant chemotherapy (NACT) has become the standard of care for high-risk breast cancer, including triple-negative (TNBC) and HER2-positive disease. As a result, handling and reporting of breast specimens post-NACT is part of routine practice, and it is important for pathologists to recognise the changes in tumour cells, tumour-associated stroma and background breast tissue induced by NACT. Familiarity with characteristic stromal features enables identification of the pre-treatment tumour site and allows confident diagnosis of pathological complete response (pCR) which is important for decisions concerning adjuvant therapy. Neoadjuvant endocrine therapy (NAET) is used less frequently than NACT; however, the SARS-COVID-19 pandemic has changed practice, with increased use as bridging therapy if surgery is delayed. NAET also induces characteristic changes in the tumour and stroma. Changes in the tumour microenvironment following NACT and NAET are also described. Immunotherapy is approved for use in advanced TNBC, and there are several trials exploring its role in early TNBC in the neoadjuvant setting. The current biomarker to determine eligibility for treatment with immune checkpoint inhibitors is programmed death ligand-1 (PD-L1) immunohistochemistry; however, this is complicated by lack of standardisation with different drugs linked to tests using different antibodies with different scoring systems. The situation in the neoadjuvant setting is further complicated by improved pCR rates for PD-L1-positive tumours in both immune therapy and placebo arms. Alternative biomarkers are urgently needed to identify which patients will derive benefit from immunotherapy and key candidates are discussed.

Chromosome 17 alterations affect the assessment of HER2 gene amplification in breast cancer (BC), but its clinical significance remains unclear. This study aimed to identify the prevalence of centromere enumeration probe 17 (CEP17) alterations, and its correlation with response to neoadjuvant therapy (NAT) in BC patients with human epidermal growth factor receptor 2 (HER2) immunohistochemistry-equivocal score.A large BC cohort (n = 6049) with HER2 immunohistochemistry score 2+ and florescent in-situ hybridisation (FISH) results was included to assess the prevalence of CEP17 alterations. Another cohort (n = 885) with available clinicopathological data was used to evaluate the effect of CEP17 in the setting of NAT. HER2-amplified tumours with monosomy 17 (CEP17 copy number 1.5 per nucleus), normal 17 (CEP17 1.5- 3.0) and polysomy 17 (CEP17 ≥ 3.0) were observed in 16, 59 and 25%, respectively, compared with 3, 74 and 23%, respectively, in HER2-non-amplified tumours. There was no significant relationship between CEP17 alterations and pathological complete response (pCR) rate in both HER2-amplified and HER2-non-amplified tumours. The independent predictors of pCR were oestrogen (ER) negativity in HER2-amplified tumours [ER negative versus positive; odds ratio (OR) = 11.80; 95% confidence interval (CI) = 1.37-102.00; P = 0.02], and histological grade 3 in HER2 non-amplified tumours (3 versus 1, 2; OR = 5.54; 95% CI = 1.61-19.00; P = 0.007).The impacts of CEP17 alterations are not as strong as those of HER2/CEP17 ratio and HER2 copy number. The hormonal receptors status and tumour histological grade are more useful to identify BC patients with a HER2 immunohistochemistry-equivocal score who would benefit from NAT.

Supplementary Materials (clean)

Hyperpolarized 13C-MRI is an emerging tool for probing tissue metabolism by measuring 13C-label exchange between intravenously injected hyperpolarized [1–13C]pyruvate and endogenous tissue lactate. Here, we demonstrate that hyperpolarized 13C-MRI can be used to detect early response to neoadjuvant therapy in breast cancer. Seven patients underwent multiparametric 1H-MRI and hyperpolarized 13C-MRI before and 7–11 days after commencing treatment. An increase in the lactate-to-pyruvate ratio of approximately 20% identified three patients who, following 5–6 cycles of treatment, showed pathological complete response. This ratio correlated with gene expression of the pyruvate transporter MCT1 and lactate dehydrogenase A (LDHA), the enzyme catalyzing label exchange between pyruvate and lactate. Analysis of approximately 2,000 breast tumors showed that overexpression of LDHA and the hypoxia marker CAIX was associated with reduced relapse-free and overall survival. Hyperpolarized 13C-MRI represents a promising method for monitoring very early treatment response in breast cancer and has demonstrated prognostic potential.Significance:Hyperpolarized carbon-13 MRI allows response assessment in patients with breast cancer after 7–11 days of neoadjuvant chemotherapy and outperformed state-of-the-art and research quantitative proton MRI techniques.

Background: Disparity between mammographic and pathological sizing of DCIS can lead to surgical overtreatment, with poor cosmetic outcomes of breast conservation surgery (BCS) or inappropriate mastectomy versus undertreatment, with subsequent need for re-excision. In addition, where mammographic size is smaller than pathological size, this may reflect an increased risk of mammographically occult residual disease post surgery; where pathological size is smaller than mammographic size there is a possibility of pathological underestimation or missed positive margins, with both scenarios resulting in increased risk of recurrence. Methods: The Sloane Project, within the UK NHS Breast Screening Programme, is a prospective cohort study of screen detected DCIS (2003-2012), with recurrence data for a median follow-up of 9 years. The NHS Breast Screening Programme screens women from age 50-70. We assessed factors associated with mammographic/pathology disparity, leading to i) 'downsizing' from pre-operative mammographic size estimation to final surgically resected pathological size or ii) 'upsizing' from pre-operative mammographic size to surgically resected pathological size. We defined 'downsizing' as pathological size 10mm or >5mm larger than mammographic size. Ipsilateral recurrence rates were determined in patients with mammographic/pathology disparity (downsized or upsized) compared to those with accurate preoperative sizing. Results: Using a 10mm size disparity, among 10829 patients, DCIS was downsized (pathological size smaller than mammographic size) in 26%, upsized in 19% and similar in 54%. Mastectomy was associated with marked mammographic/pathology disparity, with a 3.90RR of downsizing (p The results remained similar when patients prescribed endocrine therapy or radiotherapy were excluded. Re-excision (but not completion mastectomy) is associated with increased recurrence, with recurrence occurring in 237 of 5157 not requiring re-excision but 99 of 1488 requiring re-excision; RR: 1.45 (1.15-1.82). Conclusion: Large mammographic size, microcalcification casting features and young age (size overestimation) versus microcalcification and high density (size underestimation) should be considered in selecting surgery for DCIS. Mammographic/pathology disparity of only 5mm, whether this leads to downsizing or upsizing, is associated with an increased risk of ipsilateral recurrence after breast conservation. Table 1.In patients undergoing breast conservation, impact of 10mm and 5 mm mammographic/pathology disparity on ipsilateral recurrence rateTotalIpsilateral recurrence, n (%)RR (CI)Change in size of >10mmNo change3062158 (5.2%)1downsized111666 (5.9%)1.15 (0.87-1.51)upsized52036 (6.9%)1.34 (0.95-1.90)unknown19112 (6.3%)1.22 (0.69-2.15)TOTAL4889272 (5.6%)Change in size of >5mmNo change2783118 (4.2%)1downsized1953115 (5.9%)1.39 (1.08-1.78)upsized139580 (5.7%)1.35 (1.03-1.78)unknown23814 (5.9%)1.39 (0.81-2.38)TOTAL6369327 (5.1%) Citation Format: Cliona Clare Kirwan, Bridget Hilton, Karen Clements, Hilary Stobart, Matthew Wallis, Senthurun Mylvaganam, Elena Provenzano, Anthony Maxwell, Nisha Sharma, Abeer Shaaban, David Dodwell, Joanne Dulson-Cox, Elinor Sawyer, Olive Kearins, Samantha Brace-McDonnell, Sarah Pinder, Alastair M Thompson. Predictors of inaccurate pre-operative size assessment of screen detected DCIS and impact on recurrence rates [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 P1-22-01.

Background: Triple Negative Breast Cancers (TNBC) are a biologically diverse and aggressive subgroup lacking targeted therapy. Germline BRCA (gBRCA) breast cancer and TNBC share some phenotypic and molecular similarities, with 10%-20% of TNBC patients having gBRCA mutations. Homologous recombination deficient tumours are particularly sensitive to PARP inhibitors such as olaparib (Lynparza). It has been shown that adjuvant olaparib for patients with high-risk, HER2-negative early breast cancer and gBRCA pathogenic or likely pathogenic variants after adjuvant or neoadjuvant chemotherapy significantly improves 3-year invasive and distant disease-free survival compared to placebo (OlympiA). Aim: To establish if the addition of olaparib to neoadjuvant platinum based chemotherapy for basal TNBC and/or gBRCA breast cancer is safe and improves efficacy (pathological complete response (pCR) rate). Trial design: 3-stage open label randomised phase II/III trial of neoadjuvant paclitaxel and carboplatin +/- olaparib, followed by clinicians' choice of anthracycline regimen. Stage 1 and 2: Randomisation (1:1:1) to either control (3 weekly carboplatin AUC5/weekly paclitaxel 80mg/m2 for 4 cycles) or one of two research arms with the same chemotherapy regimen but with two different schedules of olaparib 150mg BD for 12 days. Stage 3: Randomisation (1:1) to either control arm or to the research arm selected in stage 2. End-points: Stage 1: Safety; Stage 2: Schedule selection using pCR rate and completion rate of olaparib using a “pick-the-winner” design. Stage 3: pCR rate. This trial includes an optional pathway (PARTNERING) aiming to establish if the addition of new agents (ATR inhibitor and PDL1 inhibitor) can improve response in those patients with evidence of residual disease before surgery. Eligibility criteria: Aged 16-70; histologically confirmed invasive breast cancer; ER-negative, HER2-negative with TNBC basal phenotype or gBRCA positive, HER2-negative irrespective of hormone status; clinical stage T1-4 N0-2; performance status 0-1; treatment commenced within 6 weeks of diagnostic biopsy; biomarker scores: TILs, CK 5/6, EGFR +/- AR. Statistical methods: The recruitment of TNBC non-gBRCA and gBRCA patients is independent. Enrichment design is applied with an overall significance level 0.05(α) and 80% power. A minimum of 780 patients will be included to detect an absolute improvement of 15% (all patients and the TNBC non-gBRCA cohort) and 20% (gBRCA patients) by adding olaparib to platinum based chemotherapy. It is planned to recruit a minimum of 188 gBRCA patients. A maximum of 15 patients will be allocated into each PARTNERING cohort. Present accrual: Recruitment commenced 27 May 2016 and 678 patients from 30 sites have been accrued to date. The IDSMC reviewed the trial after Stages 1 and 2 and recommended to continue the trial without change. Data analysis for Stage 2 revealed no safety concerns and research arm 2 (olaparib on day 3 to day 14) was selected. Stage 3 Phase I recruitment is in progress (recruiting TNBC non-gBRCA and gBRCA patients) and we anticipate moving to Phase II (recruiting gBRCA patients only) by early 2022. Four patients have been accrued to the PARTNERING optional pathway to date. The trial is open and enrolling patients to UK and international sites. Contact information: partner@addenbrookes.nhs.uk Citation Format: Lynsey M Drewett, Karen A Pinilla, Louise Grybowicz, Jerome Wulff, Alimu Dayimu, Nikolaos Demiris, Jessica Martin, Camila Maida de Pontes, Nicola Johnson, Caron Harvey, Erdem Demir, Kimberley St John Green, James Jones, Gemma Young, Anne-Laure Vallier, Wendi Qian, Andrea Machin, Karen McAdam, Rebecca Roylance, Ellen R Copson, Anne Armstrong, Nicola Levitt, Elena Provenzano, Marc Tischkowitz, Emma McMurtry, Helena Earl, Jean E Abraham. PARTNER: Randomised, phase II/III trial to evaluate the safety and efficacy of the addition of olaparib to platinum-based neoadjuvant chemotherapy in triple negative and/or germline BRCA mutated breast cancer patients [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 OT2-24-01.

Background/objectives The natural history of microinvasive carcinoma of the breast (one or more foci of invasion of 1mm or less) and its optimal management remain controversial. We analysed the frequency and outcome of patients with DCIS plus microinvasion within a large prospective cohort of screen-detected DCIS. Methods Patients with screen-detected DCIS diagnosed between 2003 and 2012 with or without microinvasion in the final surgical specimen were identified from the UK Sloane Project database. Comprehensive imaging, surgical, pathology, oncology and subsequent outcome data were collected with a median follow-up of 9 years. Results Among 11285 DCIS patients diagnosed in the UK, microinvasion was reported in 521 (4.6%). The frequency of reported microinvasion varied considerably among screening units (0-25%) but overall decreased from 7% in 2003/04 to 3% in 2011/12.As reported elsewhere, microinvasion was significantly associated with high grade DCIS (5.9% of 7182 cases) compared to 2.9% of intermediate grade and 40mm had microinvasive foci reported. Microinvasion was also associated with the presence of comedo necrosis (p Citation Format: Abeer M Shaaban, Bridget Hilton, Karen Clements, David Dodwell, Nisha Sharma, Cliona Kirwan, Elinor Sawyer, Anthony Maxwell, Matthew Wallis, Hilary Stobart, Senthurun Mylvaganam, Janet.Litherland Litherland, Samantha Brace-Mcdonnell, Joanne Dulson-Cox, Olive Kearins, Elena Provenzano, Sarah Pinder, Alastair Thompson. The diagnosis and prognosis of ductal carcinoma in situ (DCIS) with microinvasion - Results from the United Kingdom Sloane project [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 P3-12-36.

Background The variable natural history of ductal carcinoma in situ (DCIS) is poorly understood. The aim of this retrospective cohort study was to determine the outcomes of women who were diagnosed through the English National Health Service Breast Screening Programme (NHS BSP) and had no surgery for screen-detected DCIS. Method English NHS BSP databases were searched for women diagnosed with DCIS without invasive cancer on needle biopsy between 1 April 2001 and 31 March 2018 inclusive, who had no record of surgery within 6 months of diagnosis. These were cross-referenced with cancer registry data for further treatment, event information and mortality records. Details of potentially eligible women were sent to the relevant breast screening units for verification and for completion of data forms detailing clinical, radiological and pathological findings, non-surgical treatment, subsequent clinical course and outcomes. Results Data for 311 eligible women (median age 62 years) were included, with median follow-up (primary DCIS diagnosis to either surgery, development of invasive disease, death or last known to be alive) of 4.1 years (range 0.5 to 17.4 years). The median age at diagnosis was 64 years (range 47 to 90 years). Sixty (19%) women developed invasive breast cancer, 56 ipsilateral and 4 contralateral. Twenty-two women (7%) underwent surgery for DCIS (>6 months after diagnosis) and 86 (28%) died of other causes. Women with high or intermediate grade DCIS were significantly more likely to develop ipsilateral invasive breast cancer (iIBC) than those with low grade DCIS. 28/123 (23%) with high grade DCIS, 21/105 (20%) with intermediate grade DCIS, 5/76 (7%) with low grade DCIS and 2/7 (29%) with an unknown grade of DCIS developed iIBC. Ipsilateral invasion risk increased approximately linearly with time for at least 10 years. Women who developed iIBC were significantly younger than those who did not. This was driven primarily by a strong association among those with high grade DCIS. There was no significant difference in age between those with intermediate and low grade DCIS respectively who did or did not develop iIBC. The median baseline size of DCIS in women who developed iIBC was higher than in women who did not develop iIBC, both overall and in each of the three grade categories (median sizes - high grade 38 mm vs 29 mm, p=0.19; intermediate grade 35 mm vs 18 mm, p=0.31; low grade 18 mm vs 15 mm, p=0.38). This reached statistical significance for all grades combined: 37 mm (range 3-95) v 20 mm (range 3-200), p=0.02. Of the 262 women with a known microinvasion status, 8/25 (32%) with definite or possible microinvasion were subsequently diagnosed with ipsilateral invasive cancer compared to 38/237 (16%) without microinvasion (p=0.027). There was no significant association on univariable analysis between risk of iIBC and microcalcification as the predominant radiological feature (iIBC and microcalcification 47/258 vs iIBC and other radiological feature 7/46; p=0.83), the presence of histological necrosis (iIBC and necrosis, 14/89 vs iIBC and no necrosis, 31/157; p=0.49) or the use of ET (iIBC and ET 11/67 vs iIBC and no ET 45/244; p=0.86). Of the 51 invasive cancers that developed with a known grade, 46 (90%) were grade 2 or 3. Conclusion The findings suggest that women diagnosed with high or intermediate grade DCIS and those with microinvasion should continue to be offered surgery. For those with low grade DCIS there is a need for shared decision-making in the choice of surgery or active surveillance based on a discussion of the risks and benefits of the options as currently understood, and in the light of the low reproducibility of DCIS grading. Citation Format: Karen Clements, Anthony Maxwell, Bridget Hilton, Matthew Wallis, Cliona Kirwan, Hilary Stobart, Elena Provenzano, Nisha Sharma, Janet Litherland, Abeer Shaaban, David Dodwell, Joanne Dulson-Cox, Elinor Sawyer, Senthurun Mylvaganam, Olive Kearins, Samantha Brace-McDonnell, Sarah Pinder, Alastair Thompson. A longitudinal cohort study of outcomes in 311 women with unresected ductal carcinoma in situ detected through the English breast screening programme [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 P1-22-06.

Interrogation of Oncomine{trade mark, serif} (https://www.oncomine.org/) showed higher expression of eIF4E and eIF5 in breast (top panel) and lung cancer (bottom panel) compared to normal tissue. When these biomarkers were compared for gender, eIF4E and eIF5 expression was proportionately higher in male breast cancer (A, C) but not in lung cancer (B, D), respectively .

Purpose: Breast cancer affects both genders, but is understudied in men. Although still rare, male breast cancer (MBC) is being diagnosed more frequently. Treatments are wholly informed by clinical studies conducted in women, based on assumptions that underlying biology is similar.Experimental Design: A transcriptomic investigation of male and female breast cancer was performed, confirming transcriptomic data in silico. Biomarkers were immunohistochemically assessed in 697 MBCs (n = 477, training; n = 220, validation set) and quantified in pre- and posttreatment samples from an MBC patient receiving everolimus and PI3K/mTOR inhibitor.Results: Gender-specific gene expression patterns were identified. eIF transcripts were upregulated in MBC. eIF4E and eIF5 were negatively prognostic for overall survival alone (log-rank P = 0.013; HR = 1.77, 1.12–2.8 and P = 0.035; HR = 1.68, 1.03–2.74, respectively), or when coexpressed (P = 0.01; HR = 2.66, 1.26–5.63), confirmed in the validation set. This remained upon multivariate Cox regression analysis [eIF4E P = 0.016; HR = 2.38 (1.18–4.8), eIF5 P = 0.022; HR = 2.55 (1.14–5.7); coexpression P = 0.001; HR = 7.04 (2.22–22.26)]. Marked reduction in eIF4E and eIF5 expression was seen post BEZ235/everolimus, with extended survival.Conclusions: Translational initiation pathway inhibition could be of clinical utility in MBC patients overexpressing eIF4E and eIF5. With mTOR inhibitors that target this pathway now in the clinic, these biomarkers may represent new targets for therapeutic intervention, although further independent validation is required. Clin Cancer Res; 23(10); 2575–83. ©2016 AACR.

Supplementary Figure Legends

R.O.C curve analysis was used to determine the cut-off value for each antibody to determine a point of dichotomisation (graphs). Gradation of intensity of immunohistochemical staining (weak, moderate, strong) for eIF1 (A), eIF2 (B), eIF4E (C) and eIF5 (D) is shown in representative MBC TMA cores. Immunoreactivity is shown to the right of each R.O.C curve generated. Each core was individually scored with the proportion of tumour cells stained 0 - 4, followed by the intensity of staining 0 - 3. Combination scores reported were in the range 0 - 7. The Interclass Correlation Coefficient from scorer concordance of each biomarker was; eIF1 0.911 (95%CI 0.769-0.944), eIF2 0.846 (95%CI 0.736-0.910), eIF4E 0.882 (95%CI 0.755-0.913), eIF5 0.865 (95%CI 0.769-0.922). No staining was observed for eIF3 in MBC samples, although this was expressed in positive control tissue for EIF3, colon (E).

Antibody optimization for immunohistochemical assessment of CDK7

Triple-negative breast cancer (TNBC) patients commonly exhibit poor prognosis and high relapse after treatment, but there remains a lack of biomarkers and effective targeted therapies for this disease. Here, we report evidence highlighting the cell-cycle–related kinase CDK7 as a driver and candidate therapeutic target in TNBC. Using publicly available transcriptomic data from a collated set of TNBC patients (n = 383) and the METABRIC TNBC dataset (n = 217), we found CDK7 mRNA levels to be correlated with patient prognosis. High CDK7 protein expression was associated with poor prognosis within the RATHER TNBC cohort (n = 109) and the METABRIC TNBC cohort (n = 203). The highly specific CDK7 kinase inhibitors, BS-181 and THZ1, each downregulated CDK7-mediated phosphorylation of RNA polymerase II, indicative of transcriptional inhibition, with THZ1 exhibiting 500-fold greater potency than BS-181. Mechanistic investigations revealed that the survival of MDA-MB-231 TNBC cells relied heavily on the BCL-2/BCL-XL signaling axes in cells. Accordingly, we found that combining the BCL-2/BCL-XL inhibitors ABT-263/ABT199 with the CDK7 inhibitor THZ1 synergized in producing growth inhibition and apoptosis of human TNBC cells. Collectively, our results highlight elevated CDK7 expression as a candidate biomarker of poor prognosis in TNBC, and they offer a preclinical proof of concept for combining CDK7 and BCL-2/BCL-XL inhibitors as a mechanism-based therapeutic strategy to improve TNBC treatment. Cancer Res; 77(14); 3834–45. ©2017 AACR.

Details of the male breast cancer samples used at different stages of the experimental workflow

Relationship between eIF4E, eIF5 and clinico-pathological parameters

Peer reviewed: True, Funder: Egyptian Cultural and Educational Bureau, The assessment of PD-L1 expression in TNBC is a prerequisite for selecting patients for immunotherapy. The accurate assessment of PD-L1 is pivotal, but the data suggest poor reproducibility. A total of 100 core biopsies were stained using the VENTANA Roche SP142 assay, scanned and scored by 12 pathologists. Absolute agreement, consensus scoring, Cohen's Kappa and intraclass correlation coefficient (ICC) were assessed. A second scoring round after a washout period to assess intra-observer agreement was carried out. Absolute agreement occurred in 52% and 60% of cases in the first and second round, respectively. Overall agreement was substantial (Kappa 0.654-0.655) and higher for expert pathologists, particularly on scoring TNBC (6.00 vs. 0.568 in the second round). The intra-observer agreement was substantial to almost perfect (Kappa: 0.667-0.956), regardless of PD-L1 scoring experience. The expert scorers were more concordant in evaluating staining percentage compared with the non-experienced scorers (R2 = 0.920 vs. 0.890). Discordance predominantly occurred in low-expressing cases around the 1% value. Some technical reasons contributed to the discordance. The study shows reassuringly strong inter- and intra-observer concordance among pathologists in PD-L1 scoring. A proportion of low-expressors remain challenging to assess, and these would benefit from addressing the technical issues, testing a different sample and/or referring for expert opinions.

Triple negative breast cancers (TNBC) exhibit inter- and intra-tumour heterogeneity, which is reflected in diverse drug responses and interplays with tumour evolution. Here, we use TNBC patient-derived tumour xenografts (PDTX) as a platform for co-clinical trials to test their predictive value and explore the molecular features of drug response and resistance. Patients and their matched PDTX exhibited mirrored drug responses to neoadjuvant therapy in a clinical trial. In parallel, additional clinically-relevant treatments were tested in PDTXsin vivoto identify alternative effective therapies for each PDTX model. This framework establishes the foundation for anticipatory personalised therapies for those patients with resistant or relapsed tumours. The PDTXs were further explored to model PDTX- and treatment-specific behaviours. The dynamics of drug response were characterised at single-cell resolution revealing a novel mechanism of response to olaparib. Upon olaparib treatment PDTXs showed phenotypic plasticity, including transient activation of the immediate-early response and irreversible sequential phenotypic switches: from epithelial to epithelial-mesenchymal-hybrid states, and then to mesenchymal states. This molecular mechanism was exploitedex vivoby combining olaparib and salinomycin (an inhibitor of mesenchymal-transduced cells) to reveal synergistic effects. In summary, TNBC PDTXs have the potential to help design individualised treatment strategies derived from model-specific evolutionary insights.

AimsThere is little information on the impact of COVID-19 on breast pathologists. This survey assessed the effect of the COVID-19 pandemic on UK and Ireland-based breast pathologists to optimise working environments and ensure preparedness for potential future pandemics.MethodsA 35-question survey during the first wave of COVID-19 infections in the UK including questions on workload, working practices, professional development, training, health and safety and well-being was distributed to consultant breast pathologists and responses collected anonymously.ResultsThere were 135 responses from breast pathologists based in the UK and Ireland. Most participants (75.6%) stated that their workload had decreased and their productivity dropped. 86/135 (63.7%) were given the option of working from home and 36% of those who did reported improved efficiency. Multidisciplinary team meetings largely moved to virtual platforms (77.8%) with fewer members present (41.5%). Online education, including webinars and courses, was utilised by 92.6%. 16.3% of pathologists reported shortages of masks, visors or gowns as the the most common health and safety concern. COVID-19 had a significant negative impact on the physical and mental health of 33.3% of respondents. A small number of pathologists (10.4%) were redeployed and/or retrained.ConclusionThe UK and Ireland breast pathologists adapted to the rapid change and maintained service delivery despite the significant impact of the pandemic on their working practices and mental health. It is important to apply flexible working patterns and environments that improve productivity and well-being. The changes suggested should be considered for long-term shaping of breast pathology services.

The last UK breast cancer (BC) human epidermal growth factor receptor 2 (HER2) testing guideline recommendations were published in 2015. Since then, new data and therapeutic strategies have emerged. The American Society of Clinical Oncology (ASCO)/College of American Pathologists (CAP) published a focused update in 2018 that reclassified in situ hybridisation (ISH) Group 2 (immunohistochemistry (IHC) score 2+andHER2/chromosome enumeration probe 17 (CEP17) ratio ≥2.0 andHER2 copy number

For more than two decades attempts have been made to identify a subset of women diagnosed with lesions with uncertain malignant potential (B3 lesions) who could safely be observed rather than being treated with surgical excision and/or chemoprevention. Various histopathological, clinical and imaging parameters for risk recommendation have been evaluated, with little impact on clinical practice. The primary reason for surgery is to rule out an upgrade lesion to either ductal carcinoma in situ (DCIS) or invasive breast cancer (IBC). While on average 30% of these patients are upgraded after diagnostic biopsy, a large number are over treated,making this an important harm of screening.Here we evaluated stromal lymphocytes from B3 biopsies (n=264) as a predictive biomarker for upgrade. A higher number of stromal lymphocytes were observed in upgraded B3 lesions than non-upgraded (p< 0.01, zero inflated binomial model) for both ductal and papillary lesions (n=174). This observation was validated in an independent cohort (pIn conclusion, we can identify a subset of the patients at risk of upgrade with high specificity. Assessing the tumour microenvironment including stromal lymphocytes may contribute to reducing unnecessary surgeries in the clinic.

Context.— The International Collaboration on Cancer Reporting (ICCR), supported by major pathology and cancer organizations, aims at the standardization of evidence-based pathology reporting of different types of cancers, with the inclusion of all parameters deemed to be relevant for best patient care and future data collection. Lymph node metastasis is one of the most important prognostic factors in breast cancer. Objective.— To produce a histopathology reporting guide by a panel of recognized experts from the fields of pathology and surgery with elements deemed to be core (required) and noncore (recommended) to report when assessing regional lymph nodes of patients with breast cancer. Data Sources.— Published literature, previous guidelines/recommendations, and current cancer staging principles were the basis of the data set drafted by the expert panel. This was discussed in a series of teleconferences and email communications. The draft data set was then made available for public consultation through the ICCR Web site. After this consultation and ICCR ratification, the data set was finalized. Conclusions.— The ICCR has published a data set for the reporting of surgically removed lymph nodes (including sentinel lymph node biopsy, axillary lymph node dissection, targeted axillary surgery, and lymph node sampling specimens) for breast tumors. This is part of a series of 4 ICCR breast cancer–related data sets. It includes 10 core elements along with 2 noncore elements. This should allow for synoptic reporting, which is more precise, uniform, and complete than nonsynoptic reporting, and leads to improved patient outcomes.

Background The Sloane audit compares screen-detected ductal carcinoma in situ (DCIS) pathology with subsequent management and outcomes. Methods This was a national, prospective cohort study of DCIS diagnosed during 2003–2012. Results Among 11,337 patients, 7204 (64%) had high-grade DCIS. Over time, the proportion of high-grade disease increased (from 60 to 65%), low-grade DCIS decreased (from 10 to 6%) and mean size increased (from 21.4 to 24.1 mm). Mastectomy was more common for high-grade (36%) than for low-grade DCIS (15%). Few (6%) patients treated with breast-conserving surgery (BCS) had a surgical margin n = 413), median time 62 months, followed by DCIS (n = 225), at median 37 months. Radiotherapy (RT) was most protective against recurrence for high-grade DCIS (3.2% for high-grade DCIS with RT compared to 6.9% without, compared with 2.3 and 3.0%, respectively, for low/intermediate-grade DCIS). Ipsilateral DCIS events lessened after 5 years, while the risk of ipsilateral invasive cancer remained consistent to beyond 10 years. Conclusion DCIS pathology informs patient management and highlights the need for prolonged follow-up of screen-detected DCIS.

High-quality histopathology is essential for the success of clinical trials. Histopathologists have a detailed understanding of tumour biology and mechanisms of disease, as well as practical knowledge of optimal tissue handling and logistical service requirements for study delivery, such as biomarker evaluation, tissue acquisition and turnaround times. As such, histopathologist input is essential throughout every stage of research and clinical trials, from concept development and study design to trial delivery, analysis and dissemination of results. Patient recruitment to trials takes place among all healthcare settings, meaning that histopathologists make an invaluable contribution to clinical trials as part of their routine day-to-day work that often goes unrecognised. More complex evaluation of surgical specimens in the neoadjuvant setting and ever-expanding minimum data sets add to the workload of every histopathologist, not just academic pathologists in tertiary centres. This is occurring against a backdrop of increasing workload pressures and a worldwide shortage of histopathologists and biomedical scientists. Providing essential histopathology support for trials at grassroots level requires funding for adequate resources including histopathologist time, education and training, biomedical scientist and administrative support and greater recognition of the contribution made by histopathology. This paper will discuss the many ways in which histopathologists are involved in clinical trials and the challenges faced in meeting the additional demands posed by trial participation and potential ways to address this, with a special emphasis on the UK model and the Cellular-Molecular Pathology Initiative (CM-Path).

Multiple synchronous (multifocal or multicentric) ipsilateral breast cancers with heterogeneous histopathology are a rare clinical occurrence, however, their incidence is increasing due to the use of MRI for breast cancer screening and staging. Some studies have demonstrated poorer clinical outcomes for this pattern of breast cancer, but there is no evidence to guide clinical practice. In this multidisciplinary review, we reflect on pathology and molecular characteristics, imaging findings, surgical management including conservation and reconstructive options and approach to the axilla, and the role of chemotherapy and radiotherapy. Multidisciplinary discussions appear decisive in planning an appropriate surgical choice and defining the correct systemic treatment tailored to each clinical condition.

Background: Triple negative breast cancers (TNBCs) are an aggressive and diverse subgroup with no specific targeted therapies currently available. Basal TNBCs show some phenotypic and molecular similarities with germline BRCA mutated BC (gBRCA). In gBRCA patients, and potentially other homologous recombination deficiencies, these already compromised pathways may allow PARP inhibitors (olaparib) to work more effectively. PARTNER was designed to establish if the addition of olaparib to neoadjuvant platinum-based chemotherapy for gBRCA and/or basal TNBC is safe and improves efficacy (pathological complete response (pCR)). This is the first time a clinical trial provides safety data of the combination of olaparib with platinum and taxane chemotherapy in an early breast cancer setting. Methods: PARTNER is a 3-stage open label randomised Phase II/III trial of neoadjuvant Carboplatin AUC5 with weekly Paclitaxel 80mg/m2 (CP) +/- olaparib (O) 150mgBD for 12 days x 4 cycles, followed by clinicians' choice of anthracycline regimen x 3 cycles. Basal-TNBC and/or gBRCA patients are eligible for inclusion. Primary endpoints are defined by stage: Stage 1 - Safety, Stage2 - Schedule selection, and Stage 3 - Efficacy (pCR rate). The trial is now powered for efficacy analysis in the BRCA and non-BRCA population independently. Stage 1 and 2 randomization was(1:1:1) to CP: CP + O from day (D) -2: or CP + O from D 3. G-CSF was mandatory during the first 4 cycles of treatment. We present a pooled-safety analysis from Stage 1 and 2 of the two research arms only. Recruitment continues into Stage 3. Results: Between June 2016 and April 2018, 159 patients were recruited among the three arms. Overall, median age was 48.2 [range 22.3- 70.9]; 12% had Tumours >5cm, 34% had Axillary involvement; 17% were gBRCA. Adverse events (AE) that were reported as common (in at least 10% of patients) were Anaemia 23%, Neutropenia 18% and Infection 10%. Fatigue and Diarrhoea were next most prevalent with 9% and 6% respectively. The most common AE Grade >=3 were haematological events. These include Neutropenia 19%, Anaemia 15%, and Thrombocytopenia 5%. Febrile Neutropenia and Haemorrhage were reported in only 2% and 1% of cases. Grade 3 Non- haematological events were Fatigue 7%, Hypertension 3%, Headache 3% and Diarrhoea 2%. Grade 3 Sensory neuropathy was present in 2% of patients. No grade 4 sensory or motor neuropathy events were described. Serious adverse reactions related to investigational regimen were reported in 17% of patients and include fever and infection with 8 and 4 events respectively. No toxicity related deaths were reported. As per July 8th 2019, 373 patients have been recruited from which 58 were gBRCA. Conclusions: Combinations of olaparib with neoadjuvant CP chemotherapy showed an acceptable and manageable toxicity profile. Although haematological events were the most common, they did not exceed historical frequencies reported for standard chemotherapy regimens. Final safety analysis will be performed once recruitment is complete and will include detailed long-term neuropathy data. Citation Format: Karen Pinilla Alba, Emma McMurtry, Anne-Laure Vallier, Louise Grybowicz, Ellen Copson, Anne Armstrong, Rebecca Roylance, Wendi Qian, Nikolaos Demiris, Stanly Thomas, Caron Harvey, Luke Hughes-Davies, Karen McAdam, Paula del Rosario, Bryony Harrop, Elena Provenzano, Marc Tischkowitz, Helena M Earl, Jean E Abraham. Preliminary safety data from stage 1 and 2 of the phase II/III PARTNER trial: Addition of olaparib to platinum-based neoadjuvant chemotherapy in triple negative and/or germline BRCA mutated breast cancer patients [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 P3-10-05.