HER2-positive Ductal Carcinoma In Situ Research Articles

Abstract P1-04-06: Characterization of recurrence risk after lumpectomy and radiotherapy in HER2-positive ductal carcinoma in situ of the breast, using 7-gene predictive biosignature: Implications for the NSABP-B43 trial results

Abstract Background: HER2-positive versus HER2-negative ductal carcinoma in situ (DCIS) of the breast has been associated with an increased risk of local recurrence after breast-conserving surgery (BCS) and radiotherapy (RT). In recognition of this, the NASBP-B43 trial was designed to determine if two doses of trastuzumab would improve local control with BCS plus RT in HER2-positive DCIS. The trial demonstrated a non-statistically significant advantage with the addition of trastuzumab in reducing ipsilateral breast recurrence (IBR). The predictive 7-gene DCIS biosignature, DCISionRT with Residual Risk Subtype (PreludeDxTM, Laguna Hills, CA) has been shown to classify DCIS patients into two distinct groups of patients with substantially different rates of IBR following BCS plus RT. Based upon these differences in outcome, we assessed the IBR rate in patients with HER2(+) DCIS treated with BCS and RT who were or were not in the Residual Risk Subtype group defined using DCISionRT, while accounting for the varying clinicopathologic profile of the patients. Materials & Methods: DCISionRT was evaluated in a subset of 178 women with HER2(+) DCIS treated with BCS and RT as part of a multinational cohort of 926 patients from the United States, Sweden, and Australia, who were used in the validation studies for DCISionRT. Central pathology review and biosignature testing were performed at a CLIA-certified lab (Laguna Hills, CA). HER2(+) DCIS was defined as patients with a HER2(3+) immunohistochemistry >10% per ASCO/CAP guidelines. The IBR rate was calculated for the overall group of HER2(+) patients and those in the Residual Risk group. Individual patient outcome and biosignature results were analyzed using Kaplan Meier and Cox Proportional Hazard analyses. Results: The biosignature classified 113 of the 178 (63%) HER2(+) women into the Residual Risk group (DS>2.8 with RRt). Patients in the Residual Risk group had a significantly greater IBR (HR=8.3; 95%CI: 1.1,50, p=.012) over 10-years, with a corresponding 10-year total IBR rate of 16.2% (95%CI: 9.7%, 26.5%) versus 1.6% (95%CI: 0.2%, 10.9%) for all other HER2(+) patients. In univariate analysis, younger patients tended to have higher IBR rate after BCS plus RT, but only Residual Risk was significantly associated with IBR rate after BCS plus RT. Moreover, multivariable analysis demonstrated that the Residual Risk group was eight times more likely to recur after BCS and RT, while clinicopathologic factors (age, grade, tumor size) were not associated with higher IBR rates. Conclusion: The DCISionRT Residual Risk group was predictive for 10-year IBR risk after BCS plus RT in women with HER2(+) DCIS. Approximately 40% of patients with HER2(+) DCIS would be expected to achieve low rates of recurrence with BCS and RT, while about 60% of these women (classified in the Residual Risk group) would have higher recurrence rates and may benefit from further therapy, such as HER2-directed therapies. These findings suggest that if the results of the B43 trial were re-analyzed using the predictive 7-gene biosignature (DCISionRT with Residual Risk Subtype), better clarity could be gained on the true impact of trastuzumab on IBR rates in patients with HER2(+) DCIS and the patients most likely to benefit from this additional therapy. Table 1. Univariate and Multivariable Cox Proportional Hazards Analyses. Citation Format: Frank Vicini, Chirag Shah, Rachel Rabinovitch, Pat Whitworth, Julie A. Margenthaler, Brian J. Czerniecki, DAVID J. DABBS, Sheila Weinmann, Michael Leo, G Bruce Mann, Fredrik Wärnberg, jess Savala, Steven C. Shivers, Karuna Mittal, Troy Bremer. Characterization of recurrence risk after lumpectomy and radiotherapy in HER2-positive ductal carcinoma in situ of the breast, using 7-gene predictive biosignature: Implications for the NSABP-B43 trial results [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 P1-04-06.

The clinical significance of HER2 expression in DCIS.

HER2 is an established prognostic and predictive marker for patients with invasive breast cancer. The clinical and biological significance of HER2 overexpression in patients with ductal carcinoma in situ (DCIS) remains poorly defined. DCIS is a heterogeneous disease and some patients with DCIS will not progress to invasive breast cancer. However, clinically significant recurrence rates have been reported after breast-conserving surgery for DCIS and approximately half of these cases will be life-threatening invasive recurrences. Since the incidence of DCIS is rising due to the widespread use of screening mammography, there is robust interest in selecting high-risk DCIS patients that may benefit from adjuvant therapies. Molecular prognostic and predictive models in early invasive breast cancer help clinicians identify patients that will benefit from chemotherapy. Molecular subtyping and profiling could also be useful in treating DCIS patients. According to current practice guidelines, HER2 testing is not recommended in DCIS patients. Nevertheless, evidence suggests that HER2-positive DCIS cases may be associated with adverse clinicopathological parameters and increased recurrence rates. This review summarizes the existing body of evidence linking HER2 expression and ipsilateral breast cancer recurrence in DCIS. HER2, as well as its correlation with other clinicopathological markers might be a useful prognostic and predictive marker, helping clinical decision-making in DCIS patients.

Subtype-Specific Tumour Immune Microenvironment in Risk of Recurrence of Ductal Carcinoma In Situ: Prognostic Value of HER2.

Increasing evidence suggests that the significance of the tumour immune microenvironment (TIME) for disease prognostication in invasive breast carcinoma is subtype-specific but equivalent studies in ductal carcinoma in situ (DCIS) are limited. The purpose of this paper is to review the existing data on immune cell composition in DCIS in relation to the clinicopathological features and molecular subtype of the lesion. We discuss the value of infiltration by various types of immune cells and the PD-1/PD-L1 axis as potential markers of the risk of recurrence. Analysis of the literature available in PubMed and Medline databases overwhelmingly supports an association between densities of infiltrating immune cells, traits of immune exhaustion, the foci of microinvasion, and overexpression of HER2. Moreover, in several studies, the density of immune infiltration was found to be predictive of local recurrence as either in situ or invasive cancer in HER2-positive or ER-negative DCIS. In light of the recently reported first randomized DCIS trial, relating recurrence risk with overexpression of HER2, we also include a closing paragraph compiling the latest mechanistic data on a functional link between HER2 and the density/composition of TIME in relation to its potential value in the prognostication of the risk of recurrence.

Prognostic and Predictive Value of HER2 Expression in Ductal Carcinoma In Situ: Results from the UK/ANZ DCIS Randomized Trial.

HER2 is overexpressed more frequently in ductal carcinoma in situ (DCIS) than in invasive breast cancer but its prognostic significance and predictive role for radiotherapy has not been clearly established. We investigated the prognostic and predictive value of HER2 overexpression in DCIS. HER2 expression was evaluated by IHC using the HercepTest™ in samples from UK/ANZ DCIS trial participants (n = 755) with IHC 3+ expression categorized as HER2 positive for primary analyses. Sensitivity analyses included HER2 categorization as negative (IHC 0,1+), equivocal (IHC 2+), and positive (IHC 3+) and analyses restricted to a nested case-control component where 181 cases (with recurrence) were matched to 362 controls by treatment arm and age. Two-hundred and forty-five (34.4%) of evaluable 713 samples [181 ipsilateral breast events (IBE)] were HER2 positive. HER2 overexpression was associated with significantly increased risk of IBE [HR = 2.29; 95% confidence interval (95% CI), 1.64-3.14; P < 0.0001] and in situ IBE (DCIS-IBE; HR = 2.90; 95% CI, 1.91-4.40; P < 0.0001), but not of invasive IBE (I-IBE; HR = 1.40; 95% CI, 0.81-2.42; P = 0.23; Pheterogeneity = 0.04). Inclusion of HER2 significantly improved [Δχ2 (1d.f.) 12.25; P = 0.0005] a prognostic model of clinicopathological and treatment variables, HER2 being an independent predictor of IBE (multivariate HR = 1.91; 95% CI, 1.33-2.76; P = 0.0004). Radiotherapy benefit in preventing DCIS-IBE was significantly greater (Pheterogeneity = 0.04) in HER2-positive DCIS (HR = 0.16; 95% CI, 0.07-0.41) compared with HER2-negative DCIS (HR = 0.58; 95% CI, 0.28-1.19). HER2 overexpression is associated with significantly increased risk of in situ recurrence and is also predictive of radiotherapy benefit, with greater reductions in in situ but not invasive recurrences in HER2-positive DCIS.

The impact of HER2-directed targeted therapy on HER2-positive DCIS of the breast.

In invasive breast cancer, HER2 is a well-established negative prognostic factor. However, its significance on the prognosis of ductal carcinoma in situ (DCIS) of the breast is unclear. As a result, the impact of HER2-directed therapy on HER2-positive DCIS is unknown and is currently the subject of ongoing clinical trials. In this study, we aim to determine the possible impact of HER 2-directed targeted therapy on survival outcomes for HER2-positive DCIS patients. The National Cancer Data Base (NCDB) was used to retrieve patients with biopsy-proven DCIS diagnosed from 2004-2015. Patients were divided into two groups based on the adjuvant therapy they received: systemic HER2-directed targeted therapy or no systemic therapy. Statistics included multivariable logistic regression to determine factors predictive of receiving systemic therapy, Kaplan-Meier analysis to evaluate overall survival (OS), and Cox proportional hazards modeling to determine variables associated with OS. Altogether, 1927 patients met inclusion criteria; 430 (22.3%) received HER2-directed targeted therapy; 1497 (77.7%) did not. Patients who received HER2-directed targeted therapy had a higher 5-year OS compared to patients that did not (97.7% vs. 95.8%, p = 0.043). This survival benefit remained on multivariable analysis. Factors associated with worse OS on multivariable analysis included Charlson-Deyo Comorbidity Score ≥ 2 and no receipt of hormonal therapy. In this large study evaluating HER2-positive DCIS patients, the receipt of HER2-directed targeted therapy was associated with an improvement in OS. The results of currently ongoing clinical trials are needed to confirm this finding.

Analysis of risk factors associated with survival in human epidermal growth factor receptor 2-positive ductal carcinoma in situ using Korean Breast Cancer Society Database.

PurposeThis study was performed to identify the risk of mortality in patients diagnosed with human epidermal growth factor receptor 2 (HER2)-positive ductal carcinoma in situ (DCIS).MethodsWe selected 2,592 patients with HER2-positive DCIS from Korean Breast Cancer Society (KBCS) database between January 1997 and December 2019. Patients who received neoadjuvant chemotherapy were excluded. Logistic regression analysis was used to determine the association between clinical factors and overall death after adjusting for tumor and clinical characteristics. Mortality data were modified using the Statistics Korea data.ResultsThirty deaths (1.2%) were identified out of 2,592 patients in the KBCS database. In the univariate logistic regression analysis, older age, higher body mass index (BMI), type of breast surgery (mastectomy), estrogen receptor-negative, progesterone receptor-negative, and exposure to endocrine therapy were significant clinical factors associated with death. In the multivariate analysis, age (hazard ratio [HR], 1.062; 95% confidence interval [CI], 1.015–1.111; P = 0.006), BMI (HR, 1.179; 95% CI, 1.032–1.347, P = 0.016), breast surgery type (mastectomy vs. lumpectomy; HR, 0.285; 95% CI, 0.096–0.844; P = 0.024), and endocrine therapy (HR, 0.314; 95% CI, 0.099–0.995; P = 0.049) were significant risk factors for mortality.ConclusionAdvanced age, higher BMI, mastectomy, and the absence of endocrine therapy were factors associated with poor survival of patients with HER2-positive DCIS. This finding requires further validation combined with additional analysis of large databases.

HER2-Overexpressing Ductal Carcinoma In Situ Associated with Increased Risk of Ipsilateral Invasive Recurrence, Receptor Discordance with Recurrence.

The impact of HER2 status in ductal carcinoma in situ (DCIS) on the risk of progression to invasive ductal carcinoma (IDC) has been debated. We aim to use a national database to identify patients with known HER2 status to elucidate the effect of HER2 overexpression on ipsilateral IDC (iIDC) development. We performed survival analysis on patient-level data using the U.S. NCI's Surveillance Epidemiology and End Results program. We identified patients diagnosed with DCIS who underwent lumpectomy and had known HER2 status. Competing risks analysis was performed. A total of 1,540 patients had known HER2 status and met inclusion criteria. Median age at diagnosis was 60, median follow-up time was 44.5 months. A total of 417 (27.1%) patients were HER2 positive and 1,035 (67.2%) were HER2 negative. Twenty-two (1.4%) patients developed iIDC and 27 (1.8%) developed ipsilateral in situ or contralateral disease. The estimated cumulative incidence of iIDC at 5 years was 1.9% for all patients, 1.2% for HER2-negative and borderline patients, and 3.9% for HER2-positive patients. On multivariate competing risks regression, two factors were significant for iIDC: radiation (protective) therapy within 24 months (HR, 0.05; P = 0.00006) and HER2 overexpression (increased likelihood; HR, 2.72; P = 0.044). Patients with HER2-positive DCIS were more likely to have recurrences with receptor discordance. HER2 may serve as a prognostic factor for invasive recurrence and was the only lesion-related factor to significantly relate to iIDC development. It may also be associated with receptor discordance of recurrences. Further large studies will be needed to confirm these results.

Abstract 6461: HER2 positive DCIS increases short term risk of ipsilateral invasive ductal carcinoma in breast conserving surgery patients

Abstract Purpose: The impact of HER2 status in ductal carcinoma in situ (DCIS) lesions on the risk of progression to invasive ductal carcinoma (IDC) has been debated with reports of both increased and decreased risk of development of invasive breast cancer in HER2 positive patients. We aim to use a large national database to elucidate the effect of HER2 positivity on ipsilateral IDC (iIDC) development. Methods: We performed survival analyses on patient-level data using the US National Cancer Institute's Surveillance, Epidemiology, and End Results program to identify patients diagnosed with DCIS who underwent lumpectomy and had known HER2, estrogen and progesterone receptor statuses, grade, comedonecrosis, age, tumor size, and radiation therapy (RT). Competing risks analysis was performed. Results: 1,540 patients meeting inclusion criteria were identified. Median age at diagnosis was 60 with median follow-up time of 44.5 months. 22 (1.4%) patients developed iIDC and 27 (1.8%) developed ipsilateral in situ or contralateral disease. 1,035 (67.2%) patients were HER2 negative and 417 (27.1%) were HER2 positive. The estimated cumulative incidence of iIDC at 5 years was 1.9% for all patients, 1.2% (95% CI 0.6-2.1%) for HER2 negative patients, and 4.0% (95% CI 2.9-5.4%) for HER2 positive patients. On competing risks regression, two factors were significant for iIDC: RT within 20 months (HR=0.02, p=0.0002) and HER2 positivity (HR=2.81, p=0.046). Conclusions: HER2 may serve as a prognostic factor for consideration in decision making in patients for whom it is available, and in our analysis was the only lesion-related factor to significantly relate to iIDC development. Citation Format: Thomas O'Keefe, Sarah Blair, Ava Hosseini, Olivier Harismendy, Anne Wallace. HER2 positive DCIS increases short term risk of ipsilateral invasive ductal carcinoma in breast conserving surgery patients [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 6461.

HER2 overexpression in ductal carcinoma in situ is associated with ipsilateral breast cancer recurrence after conservative surgery.

BackgroundA few patients with ductal carcinoma in situ (DCIS) after breast conservative surgery would develop ipsilateral breast cancer recurrence (IBTR), either invasive or non-invasive. Study of accurate predictive biomarkers for IBTR risk are warranted. We analyzed the association of human epidermal growth factor receptor 2 (HER2) status with IBTR after conservative surgery.MethodsWe chose 213 cases of DCIS diagnosed between 2005 and 2010. Immunohistochemistry was performed for ER, PR, and HER2. The primary endpoint was IBTR. Kaplan-Meier plot was used for univariate survival analysis with log-rank test. Cox proportional hazards model was used for multivariate analysis. Hazard ratio (HR) and 95% confidence interval (CI) were calculated.ResultsWith a median follow-up 80 months, there were 29 IBTR events. In univariate analysis, patients with high grade, ER-negative, and HER2-positive breast cancers tended to have an increased risk of IBTR. In multivariate analysis, grade III and HER2-positivity were independent predictive factors for IBTR. HER2-positive DCIS had a 2.6-time risk of recurrence compared with those with HER2-negative tumors (HR=2.60; 95% CI, 1.02–6.98; P=0.044). For HER2-equivocal cases, the HR was 1.59 (95% CI, 0.40–6.34; P=0.50) compared with HER2-negative cases. Moreover, annual recurrence pattern according to HER2 status showed that HER2-positive DCIS had a recurrence peak at 3–5 years (0.3% per annum) while the annual recurrence rate of HER2-negative DCIS was very low (less than 0.1% per annum).ConclusionsThis study suggests that of HER2-overexpression might contribute to IBTR in DCIS after breast conservation.

Abstract P3-06-01: Junctional adhesion molecule-A (JAM-A) as a novel future drug target in ductal carcinoma in situ (DCIS)

Abstract Background/Aim: Increased expression of the cell-cell adhesion molecule Junctional Adhesion Molecule-A (JAM-A) has been associated with poor prognosis and HER2 expression in patients with invasive ductal breast cancera,b. However, little is known about the potential role of JAM-A in early breast cancer, specifically ductal carcinoma in situ (DCIS). Therefore the aims of this study were to investigate whether JAM-A is overexpressed in DCIS patient tissues, and whether its pharmacological antagonism could reduce functional behaviours associated with tumorigenesis. To this end, a novel inhibitor of JAM-A (JBS-2), was designed and tested in the SUM-225 cell line model of DCIS, in DCIS patient primary cultures and in two murine in vivo models of DCIS. Results: Firstly, a patient tissue microarray comprising DCIS samples (n=50) and normal adjacent tissue (NAT) (n=26) was stained for JAM-A expression and semi-quantitatively scored. 96% of DCIS tissues had moderate/high JAM-A expression in comparison to 23% of NAT. Using the HER2-positive SUM-225 breast cancer cell line, we investigated the potential value of co-targeting JAM-A and HER2/EGFR. Treatment of SUM-225 cells with JBS-2 or the dual EGFR/HER2 tyrosine kinase inhibitor lapatinib significantly inhibited cellular viability in a concentration-dependent manner. Co-treatment of SUM-225 cells with JBS-2 plus lapatinib additively inhibited cellular viability over either treatment alone. Additionally, JBS-2 reduced cellular viability in an ex vivo primary culture isolated from a DCIS patient. A pharmacokinetic study in female NOD-SCID mice treated with JBS-2 revealed no significant haematological, biochemical or pathological toxicity. Furthermore, daily intra-peritoneal administration of JBS-2 exerted significant anti-tumorigenic effects in a murine model of DCIS using female NOD-SCID mice orthotopically implanted with SUM-225 cells into the mammary fat pad. Reverse phase protein array analysis of mammary tissues post-mortem revealed drug-induced changes in several proteins including phospho-PDK1 and Caspase-8. Finally, direct intra-ductal administration of JBS-2 significantly reduced tumor size in murine xenografts which had been grown by direct intra-ductal instillation of SUM-225 cells. Conclusions: In conclusion, the role of JAM-A in DCIS is largely unknown. Increased expression of JAM-A in DCIS tissues coupled with the responsiveness of two HER2-positive DCIS mouse models to a JAM-A inhibitor suggests novel potential in investigating JAM-A inhibitors alone and in combination with HER2 inhibitors as preventative or therapeutic agents in this setting. Refernces: aBrennan K, McSherry EA, Hudson L, Kay EW, Hill AD, Young LS, Hopkins AM. Oncogene. 2013 May 30;32(22):2799-804.bMurakami M, Giampietro C, Giannotta M, Corada M, Torselli I, Orsenigo F, Cocito A, d'Ario G, Mazzarol G, Confalonieri S, Di Fiore PP, Dejana E. PLoS One. 2011;6(6):e21242. Citation Format: Ann M Hopkins, Yvonne E. Smith, Guannan Wang, Ciara Flynn, Alexander Casucci, Sri HariKrishna Vellanki, Lance Hudson, Kieran Brennan, Mattia Cremona, Saraswati Sukumar. Junctional adhesion molecule-A (JAM-A) as a novel future drug target in ductal carcinoma in situ (DCIS) [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 P3-06-01.

Discordant Marker Expression Between Invasive Breast Carcinoma and Corresponding Synchronous and Preceding DCIS.

Ductal carcinoma in situ (DCIS) is considered a potential precursor of invasive breast carcinoma (IBC). Studies aiming to find markers involved in DCIS progression generally have compared characteristics of IBC lesions with those of adjacent synchronous DCIS lesions. The question remains whether synchronous DCIS and IBC comparisons are a good surrogate for primary DCIS and subsequent IBC. In this study, we compared both primary DCIS and synchronous DCIS with the associated IBC lesion, on the basis of immunohistochemical marker expression. Immunohistochemical analysis of ER, PR, HER2, p53, and cyclo-oxygenase 2 (COX-2) was performed for 143 primary DCIS and subsequent IBC lesions, including 81 IBC lesions with synchronous DCIS. Agreement between DCIS and IBC was assessed using kappa, and symmetry tests were performed to assess the pattern in marker conversion. The primary DCIS and subsequent IBC more often showed discordant marker expression than synchronous DCIS and IBC. Strikingly, 18 of 49 (36%) women with HER2-positive primary DCIS developed an HER2-negative IBC. Such a difference in HER2 expression was not observed when comparing synchronous DCIS and IBC. The frequency of discordant marker expression did not increase with longer time between primary DCIS and IBC. In conclusion, comparison of primary DCIS and subsequent IBC yields different results than a comparison of synchronous DCIS and IBC, in particular with regard to HER2 status. To gain more insight into the progression of DCIS to IBC, it is essential to focus on the relationship between primary DCIS and subsequent IBC, rather than comparing IBC with synchronous DCIS.

Estrogen Receptor-positive Ductal Carcinoma In Situ Frequently Overexpresses HER2 Protein Without Gene Amplification

Overexpression of human epidermal growth factor receptor 2 (HER2) protein is well known to be more frequent in ductal carcinoma in situ (DCIS) than in invasive ductal carcinoma (IDC). However, the reasons for this difference are poorly understood. On the basis of the high frequency of estrogen receptor-positive (ER+) and HER2-positive (HER2+) DCIS, we hypothesized that this tumor type overexpresses HER2 protein without gene amplification and retrospectively investigated the HER2/neu gene status of 71 ER(+)HER2(+) DCIS, surgically removed during the 2007 to 2017 period, employing fluorescence in situ hybridization (FISH). To compare HER2 protein expressions between in situ and invasive components of individual tumors, 86 pT1mi/1a IDC with predominantly in situ disease were also examined. Furthermore, for comparison of FISH status between in situ and coexisting invasive components, another patient cohort, 78 FISH-positive IDC cases, were employed. To elucidate biological differences among DCIS with various combinations of ER and HER2 protein expressions, we also analyzed public microarray data of mRNA. HER2 gene amplification was observed in 35% of ER(+) and HER2 protein-overexpressing specimens, significantly lower than the 94% in ER-negative (ER-) and HER2 protein-overexpressing specimens (P<0.001). HER2 protein expression was decreased in the invasive component as compared with coexisting in situ portions in 40% of individual tumors, whereas the FISH status of these 2 components was well preserved. Moreover, ER(+) and HER2 protein-overexpressing DCIS showed significantly higher hypoxia-inducible factor-1α protein expression than the ER(+) and HER2 protein-nonoverexpressing tumors (P=0.016). We revealed that ER(+) and HER2 protein-overexpressing DCIS, especially ER-high tumors, frequently overexpress HER2 protein without gene amplification. Our data may provide novel insights for understanding the biology of DCIS.

The clinical and biological significance of HER2 over-expression in breast ductal carcinoma in situ: a large study from a single institution

BackgroundPrevious studies have reported up to 50% of ductal carcinoma in situ (DCIS), is HER2 positive, but the frequency of HER2-positive invasive breast cancer (IBC) is lower. The aim of this study is to characterise HER2 status in DCIS and assess its prognostic value.MethodsHER2 status was evaluated in a large series of DCIS (n = 868), including pure DCIS and DCIS associated with IBC, prepared as tissue microarrays (TMAs). HER2 status was assessed using immunohistochemistry (IHC) and chromogenic in situ hybridisation (CISH).ResultsIn pure DCIS, HER2 protein was over-expressed in 9% of DCIS (3+), whereas 15% were HER2 equivocal (2+). Using CISH, the final HER2 status was positive in 20%. In mixed DCIS, HER2 amplification of the DCIS component was detected in 15% with amplification in the invasive component of only 12%. HER2-positive DCIS was associated with features of aggressiveness (p < 0.0001) and more frequent local recurrence (p = 0.03). On multivariate analysis, combined HER2+/Ki67+ profile was an independent predictor of local recurrence (p = 0.006).ConclusionsThe frequency of HER2 positivity in DCIS is comparable to IBC- and HER2-positive DCIS is associated with features of poor prognosis. The majority of HER2 over-expression in DCIS is driven by gene amplification.

Abstract P3-10-28: The impact of HER2-directed targeted therapy on HER2-positive DCIS of the breast

Abstract Purpose/Objectives: In invasive breast cancer, HER2 is a well-established negative prognostic factor. However, its significance on the prognosis of ductal carcinoma in situ (DCIS) of the breast is unclear. As a result, the impact of adding HER2-directed therapy to HER2-positive DCIS is unknown and is currently the subject of ongoing clinical trials. In this study, we aim to determine the impact of HER2 status on DCIS patient outcomes as well as the possible impact of HER2-directed targeted therapy on survival outcomes for HER2-positive DCIS patients. Materials/Methods: The National Cancer Data Base (NCDB) was used to retrieve patients with biopsy-proven DCIS diagnosed from 2004-2015. Only patients with known estrogen receptor (ER) status, progesterone receptor (PR) status, and HER2 status were included in the analysis. Patients were divided into two groups based on the adjuvant therapy they received: systemic therapy (assumed to be HER2-directed targeted therapy) or no systemic therapy. Statistics included multivariable logistic regression to determine factors predictive of receiving systemic therapy, Kaplan-Meier analysis to evaluate overall survival (OS), and Cox proportional hazards modeling to determine variables associated with OS. Results: Altogether, 1927 patients met inclusion criteria; 430 (22.3%) received HER2-directed targeted therapy, while 1497 (77.7%) did not. Patients who received HER2-directed targeted therapy were likely more likely to be ER-negative. Patients who received HER2-directed targeted therapy had a higher 5-year OS compared to patients that did not (97.7% vs. 95.8%, p = 0.043). This survival benefit remained on multivariate analysis. Factors associated with worse OS on multivariate analysis included Charlson-Deyo Comorbidity Score ≥ 2 and no receipt of hormonal therapy. Conclusions: In the largest study to date evaluating HER2-positive DCIS patients, the receipt of HER2-directed targeted therapy was associated with an improvement in OS. The results of currently ongoing clinical trials are needed to confirm this finding. Citation Format: Lewis GD, Haque W, Farach A, Hatch SS, Butler EB, Schwartz MR, Bonefas E, Teh BS. The impact of HER2-directed targeted therapy on HER2-positive DCIS of the breast [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 P3-10-28.

Abstract P5-07-07: The immune microenvironment of ductal carcinoma in situ of the breast

Abstract Background: The importance of tumor-infiltrating lymphocytes (TIL) in invasive breast carcinoma for tumor development and therapeutic response is widely accepted. However, the immune microenvironment of breast ductal carcinoma in situ (DCIS) has not been fully elucidated. Evasion of immune surveillance is a necessary step in tumor evolution. In DCIS, the tumor cells are relatively protected from the immune system due to an myoepithelial cell layer and basement membrane, and intraductal immune cells are rarely detected. In contrast, in invasive disease, cancer cells and immune cells are often intermingled. Thus, understanding the immune microenviroment of in situ to invasive carcinoma transition might be particularly important to identify novel targets for early stage of tumor invasion. Aims: The aim of this study is to evaluate the clinical importance of TILs in DCIS. Methods: TILs were assessed in 133 DCIS samples with or without microinvasive disease according to the proposed method from the International Immuno-Oncology Working Group on Breast Cancer. In addition, the relationship between TILs in DCIS and clinicopathological features was evaluated. Results: TILs are present in most DCIS in varying levels. The median proportion of TILs in DCIS was 14%. Only a minority of DCIS showed &amp;gt;50% TILs, which represented only 12.8% of all cases. High TILs in DCIS was significantly associated with comedo necrosis (p&amp;lt;0.0001), high nuclear grade (p=0.0030), ER negativity (p&amp;lt;0.0001), PR negativity (p&amp;lt;0.0001), HER2 positivity (p=0.0030). Triple negative DCIS and HER2 positive DCIS had significantly higher level of TILs (p=0.0008). No correlation was demonstrated between TILs and recurrence risk. Conclusions: High TILs in DCIS was significantly associated with adverse histopathologic features. Further characterization of immune environment of DCIS may be essential for immunotherapy and breast cancer prevention. Citation Format: Yamashita N, Hisamatsu Y, Shigechi T, Tokunaga E, Saeki H, Oki E, Maehara Y. The immune microenvironment of ductal carcinoma in situ of the breast [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 P5-07-07.

Abstract PD8-09: Approximately 40% of invasive recurrences after treatment of ductal carcinoma in situ is likely to be a second primary tumor

Abstract Background. Ductal carcinoma in situ (DCIS) is a potential precursor of invasive breast cancer, because: DCIS often accompanies invasive breast cancer; its risk factors are similar to those of invasive breast cancer; and genetic markers found in DCIS are similar to the ones found in invasive breast cancer. However, clinical behavior of DCIS is still poorly understood, as there is only limited information on its long-term natural history. Altogether, this makes it difficult to understand the relatedness of DCIS and its subsequent ipsilateral invasive breast cancer (iIBC). Here, we set-up a comparison between primary DCIS and matched subsequent iIBC, by making use of pathological and molecular data. Patients and methods. For this study, we used a unique series of 155 DCIS cases which developed a subsequent iIBC during a median follow up period of 12.6 years. We assessed histological characteristics, tumor location, estrogen and progesterone receptor status, p16 expression, and HER2 and p53 overexpression. RNA sequencing and copy number sequencing was done on 78 DCIS lesions and 78 matched invasive breast cancer relapses. We determined if the iIBC lesion and DCIS lesion were related, with respect to tumor location, immunohistochemical (IHC) markers, and genomic features. Results. Based on tumor location and histological grade, &amp;gt;95% of the subsequent invasive breast cancers reflected outgrowth of residual disease. HER2 was the only IHC marker that showed a significant difference in expression between DCIS and matched iIBC: 40% of the HER2 positive DCIS was followed by a HER2 negative invasive recurrence. In addition, RNAseq data was used to classify DCIS and IBC lesions into PAM50 subtypes. 77% of the DCIS IBC pair belonged to the same subtype. The DCIS lesions showed copy number aberrations on typical breast cancer-associated loci. However, when we compared the DCIS with its matched iIBC, we saw in 41% of the cases very distinct copy number profiles, indicating either outgrow of a different tumor subclone or a second primary. Conclusion. This is the first time that a sound comparison could be made between primary DCIS and its subsequent invasive breast cancer with such a large patient group, integrating pathological and molecular data. Our results strongly suggest that many subsequent iIBCs after treatment of pure DCIS could be considered as second primary breast cancer lesions. To provide definite proof for this, in depth DNA sequencing and heterogeneity studies will be presented at SABCS 2018. Citation Format: Visser LL, Hoogstraat M, Elshof LE, van de Vijver K, Groen EJ, Almekinders MM, Bierman C, Nieboer F, de Maaker M, Kristel P, Mulder L, Schaapveld M, Schmidt MK, Lips E, Wesseling J. Approximately 40% of invasive recurrences after treatment of ductal carcinoma in situ is likely to be a second primary tumor [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 PD8-09.

Triple-negative and HER2 positive ductal carcinoma in situ of the breast: characteristics, behavior, and biomarker profile.

We compared the characteristics, clinical behavior, and biomarker profile between HER2 positive (HER2+) and triple-negative (TN) ductal carcinoma in situ (DCIS) which are considered more aggressive than other DCIS subtypes. In addition, we explored the impact of these features on its potential of progression to invasive breast carcinomas. Cases of DCIS diagnosed at the Department of Pathology, Singapore General Hospital from 1994 to 2010 were identified. TN and HER2+ DCIS cases formed the study cohort. Immunohistochemistry (IHC) was performed for ER, PR, HER2, CK14, EGFR, and p53. Comparisons of clinicopathological features, IHC results, and clinical outcomes were performed between the two groups. We evaluated 145 HER2+ and 85 TN DCIS cases. HER2 positive DCIS had significantly higher nuclear grade (p < 0.001) and more frequent necrosis (p < 0.001) than TN DCIS. HER2 positive DCIS also harbored significantly higher rates of nuclear p53 immunoreactivity (p = 0.002) than TN DCIS. Younger patients (age < 40) with HER2+ and TN DCIS demonstrated statistically significant worse invasive DFS than older women (p < 0.001). Multivariate cox regression analysis (HR 15.08, 95% CI 12.79-81.45, p = 0.002) also confirmed these findings. In addition, younger patients (age < 40) with HER2+ DCIS experienced significantly poorer prognosis when p53 was also positive (p = 0.033). HER2+ DCIS had more aggressive pathological characteristics compared to TN DCIS; accumulation of mutant p53 could possibly be contributory. Age was an independent predictor of aggressive biological behavior of HER2+ and TN DCIS. We demonstrated that younger patients with p53 positive HER2+ DCIS had significantly adverse clinical outcome.

PO-444 The emerging role of junctional adhesion molecule-A (JAM-A) as a novel drug target in ductal carcinoma in situ (DCIS)

IntroductionJunctional Adhesion Molecule-A (JAM-A) is a cell-cell adhesion protein whose increased expression is associated with poor prognosis in patients with invasive breast cancer. However little is known about its potential role in early breast cancer, specifically ductal carcinoma in situ (DCIS). We investigated whether JAM-A is overexpressed in DCIS patient tissues, and whether its pharmacological antagonism using a novel inhibitor of JAM-A signalling, termed JBS-2, utilising in vitro and in vivo models of DCIS could reduce functional behaviours associated with tumorigenicity.Material and methodsA patient tissue microarray (TMA) comprising DCIS samples (n=50) and normal adjacent tissue (NAT) (n=26) was stained for JAM-A and semi-quantitatively scored. Using a HER2/JAM-positive cell line model of DCIS, SUM-225 and an ex vivo primary DCIS breast culture, we investigated cell viability following pharmacological targeting of JAM-A and HER2/EGFR. The tolerability of JBS-2 in vivo was examined in NOD-SCID mice via intraperitoneal injection for 14 days. Finally, JBS-2 was tested for anti-tumorigenic effects alone or in combination with the HER2/EGFR tyrosine kinase inhibitor lapatinib in an in vivo mouse model of breast cancer following SUM-225 cell implantation in the mammary fat pad of NOD-SCID mice.Results and discussionsImmunohistochemical analysis revealed 96% of DCIS tissues had moderate/high JAM-A expression in comparison to 23% of NAT. Treatment of SUM-225 cells with JBS-2 or lapatinib significantly inhibited cell viability in a concentration-dependent manner. Co-treatment of SUM-225 cells with JBS-2 and lapatinib additively inhibited cell viability over either treatment alone. JBS-2 also reduced cell viability on an ex vivo DCIS primary culture. NOD-SCID mice treated with JBS-2 for 14 days revealed no haematological, biochemical or histopathological toxicity. Importantly, in a SUM-225 orthotopic murine model of DCIS, treatment with JBS-2, either alone or in combination with lapatinib, significantly inhibited tumour progression. JAM-A staining of SUM-225 tumours following treatment revealed those treated with JBS-2 had a 30% reduction in JAM-A expression in comparison to the control.ConclusionThe role of JAM-A in DCIS is unknown. Increased expression of JAM-A in DCIS tissues coupled with the responsiveness of a HER2-positive DCIS model to a JAM-A inhibitor suggests novel potential in investigating JAM-A inhibitors alone or in combination with HER2 inhibitors as preventative or therapeutic agents in this setting.

Abstract P2-03-11: The immune microenvironment of HER2-positive ductal carcinoma in situ of the breast

Abstract Background: Ductal carcinoma in situ (DCIS) consists of a heterogeneous group of tumors that can be subclassified based on their molecular profile similar to invasive breast carcinomas. DCIS ducts are often surrounded by an inflammatory infiltrate, yet few studies have focused on this inflammatory response in the different subtypes of DCIS. The role of the immune microenvironment in tumor progression and response to therapy has led to a number of effective immune-based therapies, particularly targeting the PD-1/PD-L1 axis, and these approaches may extend to breast cancer subtypes and their precursor DCIS. In this study we evaluated the inflammatory response and PD-1/PD-L1 expression in both tumor-infiltrating lymphocytes (TILs) and tumor cells in HER2-positive (HER2+) and HER2-negative (HER2-) DCIS. Design: Our population consisted of 85 cases of pure DCIS treated with surgical excision or mastectomy at our institution from 2008 to 2012. The molecular subtypes of DCIS were determined based on ER and HER2 expression. Tissue microarrays (TMAs) were constructed with 3 cores from each case to account for tumor heterogeneity. The presence of tumor-associated inflammation (TAI) was graded as absent, mild (&amp;lt;10%), moderate (10-50%) or severe (&amp;gt;50%) and the extent and intensity of PD1 and PD-L1 in the TILS and in the tumor cells were also assessed. A composite score was calculated by multiplying extent and intensity (range 0-12 with 9-12=strong). Results: Of the 85 cases, 51 were classified as Luminal A (ER+/HER2-), 15 as Luminal B (ER+/HER2+), 13 as HER2+ (ER-/HER2+) and 6 as basal-like (ER-/HER2-). Moderate/severe inflammation around DCIS correlated with HER2 expression (20/28 HER2-expressing cases (71.4 %) compared to 21/36 HER2-non-expressing cases (58.3%), p=0.005). Of interest, severe inflammation was seen almost exclusively around HER2-expressing cases (7/28, 25% vs 1/57, 1.7 %, p=0.002). Furthermore, over half of the TILs around HER2+ cases expressed PD-L1 (7/13, 54%), while only 6% of Luminal A (3/47) and none of Luminal B (0/15) or basal-like (0/6) cases did (p=0.00001). In addition, about 1/3 of the TILs around HER2+ cases expressed PD-1 (4/13, 31%), while only 8% of Luminal A (4/49) and none of Luminal B (0/15) or basal-like (0/6) cases did (p=0.004). None of the DCIS tumor cells expressed PD-1. Of interest, 15% of HER2+ cases (2/13) and 7% of Luminal B cases (1/15) expressed PD-L1 in the DCIS tumor cells. Conclusions: 1. Moderate/severe inflammation around DCIS foci correlates with HER2 expression. 2. PD-L1 expression in TILs is seen almost exclusively in HER2+ DCIS cases 3. About 1/3 of the TILs around HER2+ DCIS cases also express PD-1. 4. None of the DCIS tumor cells express PD-1. 5. Small subgroups of HER2+ and Luminal B DCIS cases show PD-L1 expression in the tumor cells themselves. The results of our study add to the understanding of the role of the immune microenvironment in DCIS, especially in the HER2+ subtype. The complex interactions between DCIS tumor cells and the local immune system may play a role in breast cancer progression and may be further exploited for immune-based therapeutic strategies. Citation Format: Ubago JM, Blanco, Jr. LZ, Siziopikou KP. The immune microenvironment of HER2-positive ductal carcinoma in situ of the breast [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P2-03-11.

Evaluating the Risk of Upstaging HER2-Positive DCIS to Invasive Breast Cancer.

Overexpression of human epidermal growth factor 2 (HER2) in invasive breast cancer (IBC) is an independent poor prognostic factor. However, the significance of HER2 overexpression in ductal carcinoma in situ (DCIS) is not well defined. The current study assessed the correlation of HER2+ DCIS with the rate of upstaging to IBC on the final pathology. The study retrospectively analyzed patients with the diagnosis of DCIS on core needle biopsy (CNB) at the authors' institution from 2009 to 2016. Data were analyzed using two-sample t tests. Multivariate analysis was performed using logistic regression. The study found that HER2+ DCIS had significantly higher rates of upstaging to IBC than HER2- DCIS (odds ratio [OR] 1.89; p=0.012). In addition, triple-positive disease was more than two times more likely to be upstaged (OR 2.5; p=0.01), whereas patients with estrogen (ER)-positive, progesterone (PR)-positive, and HER2- diseases were half as likely to be upstaged (OR 0.5; p=0.04). Upstaging did not differ for patients with triple-negative disease (OR 0.89; p=0.8). Additionally, patients with HER2+ DCIS were significantly younger regardless of ER/PR status (p=0.03). The overexpression of HER2 in patients with an initial diagnosis of DCIS on CNB were twice as likely to have IBC on the final pathology as those who did not. The results suggest that overexpression of HER2 may serve as a biomarker for risk stratification of patients with DCIS and may help to guide treatment strategies in the future. For institutions in which HER2 testing may be performed on DCIS, patients should be counseled appropriately about the risk of upgrade to IBC.