HER2 expression, copy number variation and survival outcomes in HER2-low non-metastatic breast cancer: an international multicentre cohort study and TCGA-METABRIC analysis

BACKGROUND

HER2-low breast cancer (BC) is currently an area of active interest. This study evaluated the impact of low expression of HER2 on survival outcomes in HER2-negative non-metastatic breast cancer (BC).

METHODS

Patients with HER2-negative non-metastatic BC from 6 centres within the Asian Breast Cancer Cooperative Group (ABCCG) (n = 28,280) were analysed. HER2-low was defined as immunohistochemistry (IHC) 1+ or 2+ and in situ hybridization non-amplified (ISH-) and HER2-zero as IHC 0. Relapse-free survival (RFS) and overall survival (OS) by hormone receptor status and HER2 IHC 0, 1+ and 2+ ISH- status were the main outcomes. A combined TCGA-BRCA and METABRIC cohort (n = 1967) was also analysed to explore the association between HER2 expression, ERBB2 copy number variation (CNV) status and RFS.

RESULTS

ABCCG cohort median follow-up was 6.6 years; there were 12,260 (43.4%) HER2-low BC and 16,020 (56.6%) HER2-zero BC. The outcomes were better in HER2-low BC than in HER2-zero BC (RFS: centre-adjusted hazard ratio (HR) 0.88, 95% CI 0.82-0.93, P < 0.001; OS: centre-adjusted HR 0.82, 95% CI 0.76-0.89, P < 0.001). On multivariable analysis, HER2-low status was prognostic (RFS: HR 0.90, 95% CI 0.85-0.96, P = 0.002; OS: HR 0.86, 95% CI 0.79-0.93, P < 0.001). These differences remained significant in hormone receptor-positive tumours and for OS in hormone receptor-negative tumours. Superior outcomes were observed for HER2 IHC1+ BC versus HER2-zero BC (RFS: HR 0.89, 95% CI 0.83-0.96, P = 0.001; OS: HR 0.85, 95% CI 0.78-0.93, P = 0.001). No significant differences were seen between HER2 IHC2+ ISH- and HER2-zero BCs. In the TCGA-BRCA and METABRIC cohorts, ERBB2 CNV status was an independent RFS prognostic factor (neutral versus non-neutral HR 0.71, 95% CI 0.59-0.86, P < 0.001); no differences in RFS by ERBB2 mRNA expression levels were found.

CONCLUSIONS

HER2-low BC had a superior prognosis compared to HER2-zero BC in the non-metastatic setting, though absolute differences were modest and driven by HER2 IHC 1+ BC. ERBB2 CNV merits further investigation in HER2-negative BC.

Polygenic risk scores for prediction of breast cancer risk in Asian populations

PURPOSE

Non-European populations are under-represented in genetics studies, hindering clinical implementation of breast cancer polygenic risk scores (PRSs). We aimed to develop PRSs using the largest available studies of Asian ancestry and to assess the transferability of PRS across ethnic subgroups.

METHODS

The development data set comprised 138,309 women from 17 case-control studies. PRSs were generated using a clumping and thresholding method, lasso penalized regression, an Empirical Bayes approach, a Bayesian polygenic prediction approach, or linear combinations of multiple PRSs. These PRSs were evaluated in 89,898 women from 3 prospective studies (1592 incident cases).

RESULTS

The best performing PRS (genome-wide set of single-nucleotide variations [formerly single-nucleotide polymorphism]) had a hazard ratio per unit SD of 1.62 (95% CI = 1.46-1.80) and an area under the receiver operating curve of 0.635 (95% CI = 0.622-0.649). Combined Asian and European PRSs (333 single-nucleotide variations) had a hazard ratio per SD of 1.53 (95% CI = 1.37-1.71) and an area under the receiver operating curve of 0.621 (95% CI = 0.608-0.635). The distribution of the latter PRS was different across ethnic subgroups, confirming the importance of population-specific calibration for valid estimation of breast cancer risk.

CONCLUSION

PRSs developed in this study, from association data from multiple ancestries, can enhance risk stratification for women of Asian ancestry.

Abstract P3-18-12: Achieving negative margin after repeated attempts for lumpectomy does not nullify the risk of ipsilateral breast tumor recurrences

Introduction: Currently, the widely accepted principle in managing lumpectomy margins in early breast cancer patients is to avoid the presence of tumor cell at the margin. The presence of tumor cells on lumpectomy margin can represent two different aspects of local control in breast cancer. One aspect is related to the potential technical failure that may lead to an incomplete resection of the tumor. The other aspect of positive margin is associated with a biologic nature of the tumor. For example, some tumors show features of extensive intraductal component which often result in positive lumpectomy margins and may lead to increased risk of local recurrence after breast conservation surgery. Therefore, the two-fold increase of IBTR risk with positive margin would be the reflection of the combined effect of both technical failure and the biologic features.In this study, we aimed to address this issue by investigating the IBTR rates of patients in whom negative margins were achieved by initial lumpectomy or by re-excision. Our assumption was if the IBTR rates of the two groups are identical, then the two-fold increase of IBTR risk is mostly caused by the technical incomplete resection and therefore the measures to achieve negative margins would be justified. Methods: We retrospectively reviewed the data of 5,633 patients who underwent breast conservation surgery and whole breast irradiation for invasive breast cancer between January 2004 and December 2018 from Seoul National University Hospital. During the period, a total of 828 patients had positive lumpectomy margin after their initial surgery. Among them, thirty-five patients who did not undergo re-operation were excluded due to the small sample size. Results: The median age of the studied patients was 49 years old (19-92), and nearly two third of the patients had T1 tumors (64.3%). 4,293 patients (76.7%) were node negative and 4,332 patients (77.4%) had hormone receptor positive tumors. During the median follow-up period of 76.6 ( ± 44.6) months, a total of 121 patients (2.2%) experienced IBTR. Patients who underwent re-excision to achieve negative margins experienced significantly higher rate of IBTR compared to patients in whom the margins were clear at the first lumpectomy (p=0.031, HR: 1.61; 95% C.I., 1.04-2.48). The survival curves began to separate around 4-5 years after surgery (98.5% vs 98.0% at 5 year and 97.4% vs 94.7% at 10 years of follow-up). The survival difference was more clearly observed for younger patients (p=0.033, HR 1.72; 95% C.I., 1.04-2.85 for age less than 50). When the patients were divided according to their hormone receptor and HER2 amplification status, we observed significant difference in HR+/HER2- and HR-/HER2- subtypes while the HER2-amplified tumors showed no significant differences.By using Cox regression analysis, we adjusted for other significant predictors of IBTR such as age, histologic grade, lymphovascular invasion, hormone receptor status, HER2 amplification status, and Ki-67 levels. The results of the Cox regression analysis showed that re-excision to achieve negative margin is significantly associated with the risk of IBTR after adjusting for these variables (p=0.023, HR: 1.72; 95% C.I., 1.08-2.74). Conclusion: Patients who underwent re-excision after lumpectomy for initial positive margin carry increased risk of developing IBTR even they achieve final negative margin when compared to patients with initially negative lumpectomy margin. Our observation indicate that a substantial proportion of the increasing risk of IBTR associated with positive lumpectomy margin can be attributed to the biologic characteristics of the tumor rather than technical incomplete resection.

Citation Format: Jong Ho Cheun, Hong-Kyu Kim, Han-Byoel Lee, Wonshik Han, Hyeong-Gon Moon. Achieving negative margin after repeated attempts for lumpectomy does not nullify the risk of ipsilateral breast tumor recurrences [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 P3-18-12.

Abstract P3-18-14: Assessment of quality of life and objective cosmetic outcome of breast conserving surgery with or without latissimus dorsi mini-flap in breast cancer

Introduction : Latissimus dorsi mini-flap (LDMF) with breast conserving surgery (BCS) was introduced as a useful volume replacement technique when the tumor is located in upper or outer portion of breast and the tumor size is large requiring extensive excision of breast tissue. However few studies have assessed quality of life (QoL) and objective cosmetic outcome of LDMF in breast cancer surgery. We tried to evaluate those in patients who underwent BCS with or without LDMF. Methods : This study was a prospective, single-center cohort study of patients who underwent LDMF and BCS between 2011 and 2018. As a control, patients who underwent BCS without any volume replacement and the tumor size equal to or greater than 2.5cm on the upper or upper outer of the breast on preoperative imaging. Breast Q questionnaire and body photo were taken at least 1 year after surgery. Two breast surgeons and one plastic surgeon who did not performed LDMF assessed the cosmetic outcome of the patients with photo. Results : 62 patients were in the BCS with LDMF group and 58 patients were in BCS-only group. Pathologic tumor size was significantly larger in LDMF group than BCS-only group (LDMF 3.89cm vs BCS-only 2.92cm, p= 0.001 ). Psychosocial well-being (P= 0.024), physical well-being (P= 0.000), and satisfaction with surgeon (p= 0.006) were significantly better in the BCS-only group than in the LDMF group respectively. But, there were no significant difference in neither sexual well-being (p= 0.286) nor satisfaction for breast (p=0.278) between BCS and LDMF group. In the physicians assessment, there was no significant difference in the cosmetic outcome score between the two groups (LDMF 2.56/4 vs. BCS-only 2.58/4, p= 0.884). Conclusion : In conclusion, physician assessed cosmetic outcome of LDMF was equivalent to that of BCS without LDMF although the tumor size was significantly larger in patients with LDMF. Some inferiority of QoL might be due to postoperative pain or arm movement discomfort. We are planning to evaluate objective cosmetic results using BCCT.core software.

Citation Format: Jang-il Kim, Yireh Han, Changjin Lim, Jong-Ho Cheun, Ji Gwang Jung, Hong Kyu Kim, Han-Byoel Lee, Hyeong-Gon Moon, Wonshik Han. Assessment of quality of life and objective cosmetic outcome of breast conserving surgery with or without latissimus dorsi mini-flap in breast cancer [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 P3-18-14.

Abstract P5-02-02: Development of automated 3D high-throughput drug screening platform for patient-derived breast cancer organoids

Background Patient-derived cancer organoids, which reliably conserve original features of tumors, are emerging as an excellent model for predicting therapy response and drug screening. Developing optimized 3D high-throughput drug screening platform to establish patient-derived cancer organoids and simultaneously perform drug screening is essential for personalized medicine. Methods We established normal breast organoids (n=4) and breast cancer organoids (n=10) from 20 fresh surgical specimen (normal 7, tumor 13 cases). A number (500-2000) of normal and cancer cells were automatically dispensed with the ASFA™ Spotter ST and organoids were generated by hydrogel hanging-drop culture on Cellvitro™ Pillar platform (Medical & Bio Decision, South Korea). Organoids were subjected to drug screening for 17 anticancer drugs including chemoreagents and targeted drugs in the 3D HTS system. Drug sensitivity was tested in triplicate in different concentration ranges for 5 days. Drug cytotoxic effect was assessed by calcein AM staining. Acquisition and analysis of high-content 3D organoid images were peformed using ASFA™ SCANNER (Medical & Bio Decision, South Korea). The IC50 for each drug was calculated by a sigmoidal dose-response curve, using the GraphPad Prism 9 program. We analyzed a drug response index (DRI) using a prediction alogorithm to evalute drug sensitivity (DRI&lt;-0.5) and resistance (DRI&gt;0.5). Results We summarized the DRI value of patient-derived breast organoids of 7 drugs (Table 1). 6 tumor organoids (2T, 6T, 8T, 10T, 13T, 15T) showed high sensitivity to Docetaxel, Doxorubicin, Paclitaxel, and Gemcitabin while 4 tumor organoids (1T, 9T, 14T, 16T) were less sensitive and resistant. 2 tumor organoids (10T, 16T) were sensitive to Tamoxifen and 2 tumor organoids (6T, 8T) show high sensitivity to palbociclib and erlotinib. Normal organoids show less sensitivity and resistance to chemotherapeutic drugs.

Drug response index &gt;0.5 : resistancy top 30%, Drug response index &lt;-0.5 : sensitivity top 30%. Conclusions Herein, we developed the hydrogel hanging-drop culture on Cellvitro™ Pillar platform for easily and rapidly high-throughput drug screening in patient-derived organoids using a small number of cells by testing clinically actionable drugs at different concentrations. There were different drug response indeces for each individual organoids to chemoreagents and targeted drugs. We anticipate that 3D high-throughput drug screenings platform based on patient-derived organoids can provide the information to predict drug response and allow for finding more appropriate therapy for individual patients.

Table 1.DRI values of patient-derived breast organoids of 7 drugs.Patient No.Tumor/NormalDocetaxelPaclitaxelDoxorubicinTamoxifenGemcitabinePalbociclibErlotinib1TTumor1.051.261.080.060.590.26-2TTumor-0.64-0.72-0.60-0.08-0.79--6TTumor-0.98-0.99-2.330.00-1.44-2.31-1.608TTumor-0.32-0.50-0.250.64-1.07-1.47-0.669TTumor1.050.980.610.870.430.610.4410TTumor-0.84-0.77-0.78-1.680.790.610.0913TTumor-0.87-0.430.560.70-0.510.611.1714TTumor0.861.261.180.481.81--15TTumor-1.59-1.45-1.41--0.71-0.13-16TTumor1.051.261.18-1.70-1.22-2NNormal1.051.260.650.741.810.610.7810NNormal1.05-0.910.810.870.880.610.084NNormal-0.31-0.25-0.530.25-0.190.61-1.575NNormal1.051.130.380.75-0.630.610.10

Citation Format: Jungeun Kim, Hoe Suk Kim, Ga Yeon Kim, Kyung hyeun Park, Seung yeon Ryu, Sangeun Lee, Dong Woo Lee, Bosung Ku, Han-Byoel Lee, Wonshik Han. Development of automated 3D high-throughput drug screening platform for patient-derived breast cancer organoids [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 P5-02-02.

Abstract PD15-08: Window of opportunity trial of neoadjuvant olaparib and durvalumab for triple negative or low ER-positive breast cancer

Background PARP inhibitors have proven efficacy in breast cancer patients with germline BRCA1 or BRCA2 mutations (gBRCAmt) but also have potential to be effective in cancers with defects in homologous recombination (HR) DNA repair. Moreover, synergy between PARP inhibition and immune checkpoint blockade is expected based on increased mutation burden, neoantigen expression, and immunogenic cell death. Triple negative breast cancer (TNBC) or low estrogen receptor (ER)-positive breast cancers may have diverse defects in HR repair. Methods This is a window of opportunity, serial biopsy trial of olaparib and durvalumab before standard neoadjuvant chemotherapy for TNBC or low ER+ breast cancer (NCT03594396). Patients had clinical stage II/III TNBC or low ER+ HER2- breast cancers where ER was expressed in 10% or lower in tumor cells. Olaparib 300mg bid was given for 4 weeks without rest. One dose of durvalumab 1500mg was given on day 15. Study tumor biopsy and blood sample were taken before the study treatment, after 2 weeks of olaparib before durvalumab, and 2 weeks after durvalumab at the completion of 4 weeks of olaparib. FDG-PET/MRI was taken at baseline, after 2 weeks, after 4 weeks of study treatment, and computed tomography (CT) scan at baseline and after 4 weeks. After the study treatment, standard neoadjuvant chemotherapy with 4 cycles of doxorubicin+cyclophosphamide followed by 4 cycles of docetaxel was given. Primary endpoint was the changes of tumor biology detected by serial tumor biopsy. Secondary endpoints were pathological complete response (pCR) rate, response rate, prediction of early metabolic response by functional HR status, and safety. Functional HR deficiency was assessed by counting RAD51 foci as a marker for HR repair in the baseline tumor tissues before and after 30Gy irradiation to induce DNA damage. Results Fifty-four female patients were enrolled (median age 40 years, range 24-68). ER was negative (TNBC) in 43 patients and low-positive in 11 patients. Clinical stage was II in 25 patients and III in 29 patients, and axillary lymph node involvement was in 47 patients. gBRCAmt was assessed in 53 patients and 16 (30.1%) harbored pathogenic mutations. Functional HR status as measured by RAD51 foci formation was deficient in 27 (50%) patients and proficient in 27 (50%) patients. Functional HR deficiency was related with early metabolic response by FDG-PET after 2 weeks of olaparib (response in 17/27 HR-deficient tumors [63.0%] vs. 7/27 HR-proficient tumors [25.9%]; p=.006). After 4 weeks of olaparib and durvalumab, HR-deficiency was still related to metabolic response (23/27 vs. 17/27, respectively; p=.062) but HR-proficient tumors also showed metabolic decline. Moreover, HR deficiency was also related with RECIST response measured by CT after 4 weeks (17/27 vs. 9/27; p=.029). As of June 2021, 40 patients completed the neoadjuvant treatment and surgery; among those, 30 achieved pCR (pCR rate 75%). Among 13 patients with gBRCAmt who underwent surgery, 11 achieved pCR (84.6%). Updated results on pCR will be presented. Conclusions Olaparib and durvalumab followed by standard neoadjuvant chemotherapy shows very high pCR rate in TNBC or low ER+ stage II/III breast cancer. Functional HR status as measured by RAD51 foci formation was predictive of early metabolic response to olaparib. Genomic and transcriptomic analyses are underway in the samples before, during, and after olaparib and durvalumab.

Citation Format: Seock-Ah Im, Kyung-Hun Lee, Ahrum Min, Daewon Lee, Tae Yong Kim, Han Suk Ryu, Jiwon Koh, Gi-Jeong Cheon, Yoon-Jung Shin, Yujin Kim, Hyeong-Gon Moon, Wonshik Han, Han-Byoel Lee, Morgan Diolaiti, David Quigley, Alan Ashworth, Nariya Cho. Window of opportunity trial of neoadjuvant olaparib and durvalumab for triple negative or low ER-positive breast cancer [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 PD15-08.

Abstract P5-12-11: NSDHL knockdown decreases tightly cohesive tumorsphere formation and breast cancer stem cell population

Background: Cholesterol biosynthesis pathway is commonly elevated or dysregulated in cancer cells and high cholesterol levels are associated with cancer progression. NAD(P)-dependent steroid dehydrogenase-like (NSDHL), an enzyme involved in cholesterol biosynthesis, has been implicated in maintaining cancer stem cell, but its role in regulating breast cancer stem cells (BCSC) remains unclear. This study aimed to uncover the molecular mechanisms by which NSDHL regulates BCSC properties.Methods: The knockdown of NSDHL was induced by an introduction of siRNA/shRNA into MCF-7 cells. A non-adherent 3D culture method based on polymer-X coating was applied for growing tumorspheres under serum-free condition. 3’ quant mRNA-sequencing, qRT-PCR, western blot, immunofluorescent staining, ELISA, flow cytometry and ALDEFLUOR assay were carried out. Immunodeficient NSG mice were used for orthotropic xenograft tumor models by injecting tumorspheres.Result: NSDHL knockdown reduced a tightly cohesive sphere formation. RNA-seq data revealed a significant upregulation of 253 DEGs and downregulation of 364 DEGs with &gt;2-fold change in NSDHL knockdown tumorsphere. The KEGG pathway analysis showed that DEGs were mainly enriched in TGF-β signaling pathway and cell cycle. NSDHL knockdown reduced the population of BCSCs with CD44+/CD24- phenotype and high ALDH activity as well as luminal progenitors with CD49f+/EpCAM+ phenotype along with decrease in TGF-β 1 and 3 and GLI1 in tumorsphere. In orthotropic xenograft tumor models, NSDHL knockdown strongly suppressed the tumor initiation and growth.Conclusions: Our findings reveal that NSDHL has an important role in maintaining BCSC population and tumor initiating capacity, suggesting NSDHL as an attractive therapeutic target to eliminate BCSCs, and thus preventing breast cancer initiation and progression.

Citation Format: So-Hyun Yoon, Hoe Suk Kim, Junhyuk Song, Sunkyu Kwon, Seungyeon Ryu, Moonjou Baek, Sangeun Lee, Han-Byoel Lee, Hyeong-Gon Moon, Dong-Young Noh, Sangyong Jon, Wonshik Han. NSDHL knockdown decreases tightly cohesive tumorsphere formation and breast cancer stem cell population [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 P5-12-11.

Abstract P1-05-09: Analysis of immunophenotyping of patient-derived primary breast cancer cells according to the medium composition and culture method

Purpose: Immunophenotyping is a useful tool for diagnostic and therapeutic assessment of heterogenous breast cancer cells that depend on external factors and growth conditions. The objective of this study was to characterize the phenotype of patient-derived breast cancer cells (PDBCCs) grown in different culture medium and under different conditions including 2D monolayer and non-adherent 3D spheroid culture by using flow cytometry. Methods: PDBCCs and normal breast cells were harvested from fresh surgical specimens (N=11) of breast tumor and normal tissues. PDBCCs were grown in various culture media under monolayer, spheroid and organoid conditions. Flow cytometry, qRT-PCR, ALDEFLUOR assay, β-galactosidase staining and RNA-seq were performed. Results: PDBCC growth rates were different for each patient case. As compared with full media, A83-01 removal increased EpCAM+CD24+ cells (1.8-fold, p&lt;0.029) and decreased EpCAM-CD44high/+CD24- (0.45-fold, p=0.029). EGF removal increased EpCAM+CD49f− cells (14.1-fold, p=0.029). Removal of both EGF and A83-01 induced senescent cells with high β-galactosidase activity. EpCAM-CD44high/+CD24- cells, ALDHhigh cells, and EpCAMlow/-CD49f+ cells were enriched by 3D spheroids relative to 2D monolayer. 562 genes with 2-fold change and, p-value&lt;0.05 were differentially expressed in 3D spheroids compared to 2D monolayers. Based on public database, many genes associated with poor prognosis in 3D spheroids were identified (Table 1). Table 1. Clinically poor prognosis-associated DEGs were selected from tumor spheroids based on recurrence-free survival analysis using Kaplan-Meier Plotter on database that includes estrogen receptor positive patients. B, coefficient of regression; HR, hazard ratio; CI, confidence interval; ER, estrogen receptor, HER2, human epidermal receptor 2; RFS, recurrent free survival; FC, fold change. Conclusion: PDBCC phenotypes can be modulated by external factors and culture methods. Cancer stem-like properties of PDBCCs can be enriched by 3D spheroids. Future studies to explore the specific molecular mechanisms underlying these observations may provide new molecular targets for the development of therapies for heterogenous breast cancer

Clinically poor prognosis-associated DEGs based on recurrence-free survival analysisGenes symbolLog2(FC) P&lt;0.05Prognosis95% CI for Exp(B)HRlowerupperP-valueTop 30 of DEGsUpregulated genesMMP110.90Poor1.611.381.877.5e-10BMP68.85Poor1.21.021.040.024MYCN7.20Poor1.231.041.460.015COL22A17.12Poor1.571.172.110.0026CYP1A1(CP11)7.01Poor1.271.051.530.012PGBD56.78Poor1.221.051.420.011S100P6.70Poor1.491.281.733.3e-07CALML56.24Poor1.271.0810480.0034PPP2R2C6.19Poor1.491.131.970.005PMEPA16.07Poor1.181.011.40.043Downregulated geneFOSB-6.36Poor0.630.520.762e-06LINC00844-6.01Poor0.670.480.930.017DLK2-5.46Poor0.820.710.960.011IL33-5.31Poor0.650.550.773.1e-7SCN2B-5.09Poor0.80.670.950.0099CLDN19-4.80Poor0.660.490.890.0065FOS-4.67Poor0.670.570.798.5e-7EGR1-4.63Poor0.680.580.822.3e-0.5JAM2-4.62Poor0.80.680.950.0092MYH11-4.38Poor0.760.660.890.00045ALPL-4.35Poor0.820.710.960.015

Citation Format: Seungyeon RYU, Hoe Suk Kim, So-Hyun Yoon, Sangeun Lee, Junhyuk Song, Moonjou Baek, Han-Byoel Lee, Sangyong Jon, Wonshik Han. Analysis of immunophenotyping of patient-derived primary breast cancer cells according to the medium composition and culture method [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 P1-05-09.

Abstract P4-07-07: Metaplastic carcinoma of the breast has comparable prognosis to non-metaplastic triple negative breast cancer despite poor response to chemotherapy

Introduction Metaplastic carcinoma (MC) of the breast is a rare pathologic entity accounting for &lt;1% of all invasive breast cancers and is generally negative for hormone receptors and HER2. They often show more aggressive characteristics and are resistant to treatment. Although triple negative breast cancers (TNBCs) have good response to neoadjuvant chemotherapy (NAC) and a pathologic complete response (pCR) rate of about 40%, benefit of NAC for MC is not clear. The aim of this study was to compare the Clinicopathologic characteristics and prognosis of MC with non-MC TNBC, and assess the usefulness of NAC for MC. Methods Retrospective chart review of TNBC patients who underwent breast surgery at Seoul National University Hospital between January 2000 and December 2018 were included for analysis. Clinicopathologic features including age, TNM stage, Ki-67 and histologic grade were collected. For patients who had received NAC, tumor size on ultrasound before NAC and pathologic size of residual tumor was used to assess responsiveness to NAC. We used 3:1 propensity score matching according to age, neoadjuvant chemotherapy, pT stage, pN stage. Kaplan-Meier analysis and log-rank test were performed. Results Among 1783 TNBC patients included for analysis, 82 (4.59%) were MC and 1701 (95.34%) were non-MC. MC had a worse DFS and OS. After propensity score matching, there was no difference in survival outcomes. The 5-year disease-free survival and overall survival between MC vs. non-MC TN was 61.9% vs. 73.0% (HR 1.379, 95% CI 0.594-3.202, p-value = 0.430) and 71.4% vs. 74.6% (HR 1.007, 95% CI 0.393-2.579, p-value = 0.480), respectively. The proportion of patients who received NAC among MC and propensity matched non-MC TNBC were 21/82 (25.6%) and 63/1701 (3.7%), respectively. The pathologic complete response rate for all and propensity score matched non-MC TNBC was 76/364 (20.9%) and 11/63 (17.5%), respectively, whereas no MC patients achieved a pathologic complete response (HR 1.404 95% CI 1.213-1.624, p-value = 0.058). Conclusions MC has comparable prognosis compared to non-MC TNBC in terms of disease-free survival and overall survival, while showing lower rate of pathologic complete response after NAC. Upfront surgery may be more beneficial for MC. A prospective study with larger number of patients evaluating the role of NAC in MC is warranted.

Citation Format: Changjin Lim, Jang-il Kim, Yireh Han, Jong-ho Cheun, Ji Gwang Jung, Hong Kyu Kim, Hyeong-Gon Moon, Wonshik Han, Han-Byoel Lee. Metaplastic carcinoma of the breast has comparable prognosis to non-metaplastic triple negative breast cancer despite poor response to chemotherapy [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 P4-07-07.

Abstract OT1-04-02: The NAUTILUS trial (No Axillary sUrgical Treatment In clinically Lymph node negative patients after UltraSonography): A prospective multicenter randomized phase III trial (NCT04303715)

Background. Sentinel lymph node biopsy (SLNB) is currently the standard axillary staging procedure for clinically node-negative breast cancer. According to the ACOSOG Z0011 trial, axillary lymph node dissection (ALND) is now often omitted for clinically node-negative cT1-2 breast cancer patients undergoing breast-conserving surgery even if 1 or 2 metastatic lymph nodes (LN) are identified. It was shown that radiotherapy contributes to regional control of the axilla non-inferior to ALND even in the presence of metastatic LNs. Furthermore, LN metastasis has a limited role in planning adjuvant systemic therapy for hormone receptor-negative breast cancers, and also for hormone receptor-positive, HER2-negative breast cancer with increased use of genomic assays. SLNB is not without complications and omitting axillary staging operation could improve quality of life. Trial Design. In this multicenter, phase III randomized controlled trial including 9 study sites in South Korea, we plan to 1:1 randomize 1734 patients to either omit SLNB (Arm 1) or receive SLNB (Arm 2). Additional ALND can be performed according to the discretion of the surgeon according to the SLNB results. All patients must receive whole-breast irradiation ± tumor bed boost. The recommended upper margin of the radiation field is within 2cm of the humeral head. ClinicalTrials.gov identifier: NCT04303715. Eligibility. Inclusion criteria: women ≥19 years; cT1-2N0M0 unilateral invasive breast carcinoma; all molecular subtypes; clinically and radiologically tumor size ≤ 5cm; clinically- and ultrasonogram-negative axillary lymph nodes, or no tumor on core needle biopsy or fine needle aspiration cytology in case of suspicious lymph nodes; candidate for breast-conserving surgery with no restriction to radiotherapy and adequate systemic therapy. Exclusion criteria: history of any malignancy within 5 years (exception: thyroid cancer and well-treated skin cancer except melanoma); bilateral breast cancer; neoadjuvant chemotherapy; candidate for total mastectomy; male breast cancer. Specific Aims. Primary objective is to test the hypothesis that omitting SLNB for breast cancer is non-inferior to axillary staging operation in terms of 5-year disease-free survival. Secondary objectives are to compare overall survival, distant metastasis-free survival, locoregional recurrence, quality of life assessment, and DFS and axillary recurrence according to molecular subtypes. Statistical Methods. With an expected 5-year DFS of 86% for Arm 2, Arm 1(SLNB omission) will be assessed with a non-inferiority limit of 5% and hazard ratio of 1.4, power 80%, and significance level of 5%, where 224 events are required. The calculated sample size is 780 per study arm, resulting in a total of 1,734 patients assuming a 10% drop-out rate. Present Accrual and Target Accrual. The first patient was randomized on September 15, 2020. As of July 9, 2021, 480 patients have been randomized. Target accrual of 1734 patients is expected to be complete by April 2023, with the primary endpoint analysis expected in 2028.

Citation Format: Han-Byoel Lee, Ji Gwang Jung, Jung Min Chang, Ji Hyun Chang, Woo Kyung Moon, Kyung Hwan Shin, Il Yong Chung, Seok Jin Nam, Eun-Kyu Kim, Seeyoun Lee, Seho Park, Woo Sung Lim, Yongsik Jung, Wonshik Han. The NAUTILUS trial (No Axillary sUrgical Treatment In clinically Lymph node negative patients after UltraSonography): A prospective multicenter randomized phase III trial (NCT04303715) [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 OT1-04-02.

A Randomized Controlled Trial for Doing vs. Omitting Intraoperative Frozen Section Biopsy for Resection Margin Status in Selected Patients Undergoing Breast-Conserving Surgery (OFF-MAP Trial)

Purpose

Intraoperative frozen section biopsy is used to reduce the margin positive rate and re-excision rate and has been reported to have high diagnostic accuracy. A majority of breast surgeons in the Republic of Korea routinely perform frozen section biopsy to assess margins intraoperatively, despite its long turnaround time and high resource requirements. This study aims to determine whether omitting frozen section biopsy for intraoperative margin evaluation in selected patients is non-inferior to performing frozen section biopsy in terms of resection margin positivity rate.

Methods

This study is a phase III, randomized controlled, parallel-group, multicenter non-inferiority clinical trial. Patients meeting the inclusion criteria and providing written informed consent will be randomized to the “frozen section biopsy” or “frozen section biopsy omission” group after lumpectomy. Patients with clinical stage T1–T3 disease who are diagnosed with invasive breast cancer by core-needle biopsy and plan to undergo breast-conserving surgery will be included in this study. If a daughter nodule, non-mass enhancement, or microcalcification is identified on preoperative imaging, these features must be within 1 cm of the main mass for inclusion in the trial. The target sample size is 646 patients per arm. The primary endpoint will be the resection margin positive rate, and the secondary endpoints include the reoperation rate, operating time, residual cancer after reoperation, residual cancer after re-excision according to the frozen section biopsy result, resection volume, patient quality of life, and cost-effectiveness.

Discussion

This is the first randomized clinical trial utilizing frozen section biopsy for intraoperative margin evaluation and aims to determine the non-inferiority of omitting frozen section biopsy in selected patients compared to performing frozen section biopsy. We expect that this trial will help surgeons perform the procedure more efficiently while ensuring patient safety.

Trial Registration

ClinicalTrials.gov Identifier: NCT03975179; Clinical Research Information Service Identifier: KCT0004606

Comparison of Long-Term Oncological Outcomes in Oncoplastic Breast Surgery and Conventional Breast-Conserving Surgery for Breast Cancer: A Propensity Score-Matched Analysis

PURPOSE

The oncoplastic breast-conserving surgery (OPS) technique, combined with the principles of oncological safety and plastic surgery, results in complete tumor resection while preserving the natural appearance of the breast. The purpose of this study was to evaluate the long-term oncological results after OPS compared with conventional breast-conserving surgery (BCS) for early breast cancer.

METHODS

The medical records of patients who underwent breast cancer surgery and adjuvant radiation therapy at Seoul National University Hospital between 2011 and 2014 were reviewed. Ipsilateral breast tumor recurrence (IBTR)-free survival rate and recurrence-free survival (RFS) rates were compared between the OPS and BCS groups.

RESULTS

One-to-one propensity score matching was conducted, yielding 371 patients in each group. The mean tumor distance from the nipple was shorter, and the mean retrieved specimen size and pathologic tumor size, including ductal carcinoma in situ, were larger in the OPS group than in the conventional BCS group (p < 0.001). Surgical margin positivity was not significantly different between the two groups (p = 0.777). The surgical technique was not significantly associated with IBTR (OPS versus conventional BCS, 5-year survival rate, 96.9% vs. 98.6%; p = 0.355) and RFS (5-year survival rate, 92.9% vs. 94.5%; p = 0.357) on the log-rank test. Multivariate analysis revealed that OPS versus conventional BCS was not significantly associated with survival outcomes.

CONCLUSION

We observed no significant differences in long-term IBTR and RFS between the OPS and conventional BCS groups in this retrospective analysis. OPS can be an oncologically and surgically safe alternative option for conventional BCS for early breast cancer.

Peptidyl-prolyl cis-trans isomerase NIMA-interacting 1 directly binds and stabilizes Nrf2 in breast cancer

Peptidyl-prolyl cis-trans isomerase NIMA-interacting 1 (Pin1) has been frequently overexpressed in many types of malignancy, suggesting its oncogenic function. It recognizes phosphorylated serine or threonine (pSer/Thr) of a target protein and isomerizes the adjacent proline (Pro) residue, thereby altering folding, subcellular localization, stability, and function of target proteins. The oncogenic transcription factor, Nrf2 harbors the pSer/Thr-Pro motif. This prompted us to investigate whether Pin1 could bind to Nrf2 and influence its stability and function in the context of implications for breast cancer development and progression. The correlation between Pin1 and Nrf2 in the triple-negative breast cancer cells was validated by RNASeq analysis as well as immunofluorescence staining. Interaction between Pin1 and Nrf2 was assessed by co-immunoprecipitation and an in situ proximity ligation assay. We found that mRNA and protein levels of Pin1 were highly increased in the tumor tissues of triple-negative breast cancer patients and the human breast cancer cell line. Genetic or pharmacologic inhibition of Pin1 enhanced the ubiquitination and degradation of Nrf2. In contrast, the overexpression of Pin1 resulted in the accumulation of Nrf2 in the nucleus, without affecting its transcription. Notably, the phosphorylation of Nrf2 at serine 215, 408, and 577 is essential for its interaction with Pin1. We also identified phosphorylated Ser104 and Thr277 residues in Keap1, a negative regulator of Nrf2, for Pin1 binding. Pin1 plays a role in breast cancer progression through stabilization and constitutive activation of Nrf2 by competing with Keap1 for Nrf2 binding.

Abstract PS10-13: Impact of trastuzumab on Ipsilateral breast tumor recurrence after breast conserving surgery

Background: Trastuzumab is well known to be effective to control locoregional recurrence and distant metastasis of human epidermal growth factor receptor 2 (HER2)-overexpressing breast tumor. However, few studies have reported the effect of ipsilateral breast tumor recurrence (IBTR) in spite of higher incidence of IBTR for HER2 overexpressing subtype than other subtypes. The purpose of this study is to investigate the difference in the incidence of IBTR of HER2-overexpressing breast tumor according to adjuvant trastuzumab.

Methods: We retrospectively reviewed 996 patients who had done surgery for HER2-overexpressing breast cancer between January 2000 and December 2017 in our institution. Patients with tumors smaller than 0.5cm without axillar node metastasis were excluded. As regarding IBTR as recurrence “in” the ipsilateral breast, only patients who had done breast conserving surgery were included.

Results: There were 735 patients who had finished adjuvant trastuzumab as first planned and 555 patients with hormone receptor positive. Median follow-up period for all patients was 70.7 months (range 12.7-239.6 months). The 10-year IBTR-free survival rate showed a significant benefit for the group treatment with trastuzumab than the group without trastuzumab (97.0% versus 91.9%; p=0.007). In a multivariate analysis, presence of lymphovascular invasion (Hazard ratio [HR], 2.53; 95% Confidence interval [CI], 1.19 - 5.41), closed or involved resection margin (HR, 2.62; 95% CI, 1.20 - 5.74), positive hormone receptor (HR, 3.70; 95% CI, 1.69 - 8.08), positive axillar lymph node (HR, 5.21; 95% CI, 1.75 - 15.57), and omitted or uncompleted adjuvant trastuzumab (HR, 2.72; 95% CI, 1.11 - 6.67) were independent predictors of IBTR. However, subgroup analysis of the patients with hormone receptor negative tumor showed no benefit of adjuvant trastuzumab (98.1% versus 96.6%, p=0.669) while it controlled IBTR for hormone receptor positive tumor (95.7% versus 86.2%; p=0.002). When additionally analzyed, trastuzumab showed benefit for 10-year locoregional recurrence-free survival (95.5% versus 89.7%, p=0.012) and distant metastasis-free survival (93.5% versus 77.8%, p&lt;0.001).

Conclusions: Trastuzumab has a clinical benefit in not only locoregional recurrence but also IBTR among HER2-overexpression breast cancer, especially with negative hormone receptor.

Citation Format: Jong Ho Cheun, Han-Byoel Lee, Hyeong-Gon Moon, Dong-Young Noh, Wonshink Han. Impact of trastuzumab on Ipsilateral breast tumor recurrence after breast conserving surgery [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 PS10-13.

Abstract PS2-42: Identify breast cancer patients with pathologic complete response in the breast after neoadjuvant systemic treatment - an international, multicenter analysis

Purpose: Neoadjuvant systemic treatment elicits a pathologic complete response (pCR) in an average of 35% of women with breast cancer. In such cases, breast surgery may be considered overtreatment. However, imaging and vacuum-assisted biopsy (VAB) alone showed high rates of missed cancer compared to standard breast surgery. We therefore evaluated multivariate algorithms using patient, tumor, and VAB variables to accurately identify patients with breast pCR.

Methods: We developed and tested three multivariate approaches: elastic net regression, Support Vector Machines (SVM), and a deep neural network. We analyzed 452 patients, randomly partitioned into training and test samples (2:1 ratio), who participated in three prospective studies assessing the feasibility of VAB to accurately detect residual disease after neoadjuvant systemic treatment (NST). The studies were conducted at 23 sites in the United States, Germany, and South Korea. The trials enrolled women who presented with clinical stage I-III breast cancer of any biological subtype and a partial or complete response to NST confirmed by ultrasonography, mammography, or magnetic resonance imaging; all patients underwent guideline-adherent surgery. We compared the performance of the multivariate algorithms to the histopathologic evaluation of disease response in the surgical specimen (reference standard) - false-negative rate (FNR, missed residual cancer) and specificity (identification of breast pCR) were the main outcome measures. The best performing algorithm on the test set with respect to sensitivity and specificity was validated using data of an independent fourth trial. We compared the performance of the multivariate approaches to the performance of imaging and/or VAB.

Results: In the test set (n=152), elastic net regression, SVM and the neural network revealed an FNR of 1.2% (1 of 85 patients with missed residual disease). Specificity of the elastic net regression was 46.3% (31 of 67 women with surgically confirmed breast pCR identified), of the SVM 62.7% (42 of 67) and of the neural network 67.2% (45 of 67). All multivariate algorithms performed better than imaging or VAB: FNR 25.9% (22 of 85) and 16.5% (14 of 85), respectively. Subsequent external validation (n=50) of the neural network algorithm showed a false-negative rate of 0% (0 of 27) and a specificity of 65.2% (15 of 23). The area under the ROC curve for the deep neural network was 0.97 (95% CI, 0.94 to 1.00). Analyzing the coefficients of the elastic net regression (regularized beta; ß) showed that the lesion diameter on imaging after NST (ß = 0.31) and VAB results (ß = 0.49) were the most important variables in the prediction of residual tumor. Other variables were also important: age (ß = 0.18), in-situ in the initial diagnostic (not VAB) biopsy (ß = 0.11), difficulties during the pathologic evaluation of the VAB specimen (ß = 0.11); needle size 7G (ß = -0.06, as opposed to 8G, 9G, 10G), multicentricity on imaging after NST (ß = 0.06), hormone-receptor positivity (ß = 0.01), and a clip marker positioned within the (former) lesion (ß = -0.01, as opposed to a clip marker positioned &lt;5mm or &gt;5mm from the lesion

Conclusion: A multivariate algorithm can accurately select breast cancer patients without residual disease after neoadjuvant treatment. This finding may pave the way to study omission of breast surgery in these patients in the future.

Performance of multivariate algorithms compared to imaging and vacuum-assisted biopsyFalse-negative rate - value (95% CI)Specificity - value (95% CI)Negative predictive value - value (95% CI)Positive predictive value - value (95% CI)Test set (n=152)Imaging25.9% (17.0-36.5%)61.2% (48.5-72.9%)65.1% (52.0-76.7%)70.8% (60.2-79.9%)VAB16.5% (9.3-26.1%)89.6% (79.7-95.7%)81.1% (70.3-89.3%)91.0% (82.4-96.3%)Imaging + VAB5.9% (1.9-13.2%)52.2% (39.7-64.6)87.5% (73.2-95.8%)71.4% (62.1-79.6%)Elastic net regression1.2% (0.0-6.4%)46.3% (34.0-58.9%)96.9% (83.8-99.9%)70.0% (61.0%-78.0%)Support Vector Machine1.2% (0.0-6.4%)62.7% (50.0 - 74.2%)97.7% (87.7-99.9%)77.1% (68.0-84.6%)Deep Neural Network1.2% (0.0-6.4%)67.2% (54.6-78.2%)97.8% (88.5-99.9%)79.3% (70.3-86.5%)Validation set (n=50)Deep Neural Network0.0% (0.0-12.8%)65.2% (42.7-83.6%)100% (78.2-100%)77.1% (59.9-89.6%)

Citation Format: André Pfob, Chris Sidey-Gibbons, Han-Byoel Lee, Marios Konstantinos Tasoulis, Vivian Koelbel, Michael Golatta, Gaiane M. Rauch, Benjamin D. Smith, Vicente Valero, Fiona MacNeill, Wonshik Han, Walter Paul Weber, Geraldine Rauch, Henry Kuerer, Joerg Heil. Identify breast cancer patients with pathologic complete response in the breast after neoadjuvant systemic treatment - an international, multicenter analysis [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 PS2-42.

Abstract PS7-36: Subtype-dependent locoregional recurrence patterns in different subtypes of breast cancer: A retrospective analysis of 16,505 patients over 10 years of follow-up

Background While numerous studies have consistently reported that the molecular subtypes of breast cancer are associated with different patterns of distant metastasis, the impact of molecular subtypes on the locoregional recurrence has not been thoroughly investigated. Currently, major guidelines in breast cancer recommend annual mammography for locoregional surveillance. In the present study, we investigated the patterns of locoregional recurrence in a large cohort of breast cancer patients who underwent standardized treatment at a single institution.

Methods We retrospectively reviewed the clinical records of all patients who underwent breast cancer surgery for stage I-III diseases between January 2000 and December 2018. The patients with ductal carcinoma in situ who underwent standard treatment were also included. The events were classified into ipsilateral breast cancer recurrence (IBTR), locoregional recurrence (LRR) and contralateral breast cancer (CBC). All IBTR events were included in the LRR events. The patients with initial stage IV breast cancer, with recurrence breast cancer previously treated at elsewhere, or patients with insufficient follow-up period were excluded.

Results A total of 16,505 patients were identified and included in the analysis. For all patients, the rate of IBTR, LRR, and CBC at 10 year was 2.6%, 4.9% and 1.9%, retrospectively. There was no significant association between the IHC-based molecular subtype and tumor recurrences in the 1,535 patients with ductal carcinoma in situ. For 14,970 patients with invasive disease, we observed significant differences in IBTR, LRR, and CBC between different molecular subtypes. For all events, HR-/HER2+ subtype and HR-/HER2- subtype showed worst recurrence-free survival compared to other subtypes (p&lt;0.001). However, when each event-types was separately analyzed, we observed a unique subtype-specific outcome differences according to different types of events. For IBTR, HR-/HER2- subtype showed significantly worse outcome compared to HR+ tumors (p&lt;0.001) but HR-/HER2+ subtype showed significantly higher number of events even compared to HR-/HER2- (p=0.026). For LRR, HR-/HER2+ and HR-/HER2- subtypes showed similar degree of worsening outcome compared to other subtypes (p&lt;0.001). For CBC, HR+/HER2- subtype showed significantly better outcome compared to other subtypes (p&lt;0.001). Interestingly, while the risk of development of LRR in HR+ subtypes was steady over time, the HR- subtypes showed increased risk of developing LRR during the first three years of follow-up. After that, all subtypes showed constant risk of developing LRR. In HR-/HER2+ subtype and HR-/HER- subtype, 68.2% and 75.5% of LRR events were manifested during the first three years, respectively. In contrast, HR+/HER2- and HR+/HER2+ subtypes had 43.5% and 56.5% of LRR events during the same period. In terms of CBC, all subtypes showed consistent annual risk of developing CBC during the follow-up period. The HR-/HER2- showed significantly increased risk of developing CBC compared to HR+/HER2- subtype until seven years of follow-up.

Conclusions We propose a subtype-specific locoregional and contralateral breast recurrence patterns in operable breast cancer patients by using a large cohort of breast cancer patients with sufficient long-term follow-up. These findings suggest a subtype-based tailored approach for locoregional and contralateral breast recurrences after curative treatment

Citation Format: Jong Ho Cheun, Han-Byoel Lee, Wonshink Han, Dong-Young Noh, Hyeong-Gon Moon. Subtype-dependent locoregional recurrence patterns in different subtypes of breast cancer: A retrospective analysis of 16,505 patients over 10 years of follow-up [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 PS7-36.

S100A8/A9 mediate the reprograming of normal mammary epithelial cells induced by dynamic cell-cell interactions with adjacent breast cancer cells

To understand the potential effects of cancer cells on surrounding normal mammary epithelial cells, we performed direct co-culture of non-tumorigenic mammary epithelial MCF10A cells and various breast cancer cells. Firstly, we observed dynamic cell-cell interactions between the MCF10A cells and breast cancer cells including lamellipodia or nanotube-like contacts and transfer of extracellular vesicles. Co-cultured MCF10A cells exhibited features of epithelial-mesenchymal transition, and showed increased capacity of cell proliferation, migration, colony formation, and 3-dimensional sphere formation. Direct co-culture showed most distinct phenotype changes in MCF10A cells followed by conditioned media treatment and indirect co-culture. Transcriptome analysis and phosphor-protein array suggested that several cancer-related pathways are significantly dysregulated in MCF10A cells after the direct co-culture with breast cancer cells. S100A8 and S100A9 showed distinct up-regulation in the co-cultured MCF10A cells and their microenvironmental upregulation was also observed in the orthotropic xenograft of syngeneic mouse mammary tumors. When S100A8/A9 overexpression was induced in MCF10A cells, the cells showed phenotypic features of directly co-cultured MCF10A cells in terms of in vitro cell behaviors and signaling activities suggesting a S100A8/A9-mediated transition program in non-tumorigenic epithelial cells. This study suggests the possibility of dynamic cell-cell interactions between non-tumorigenic mammary epithelial cells and breast cancer cells that could lead to a substantial transition in molecular and functional characteristics of mammary epithelial cells.

Clinical significance of HER2 status in T1bN0 breast cancer: a nationwide study from the Korean Breast Cancer Society

PURPOSE

The prognosis of patients with node-negative T1b tumors according to human epidermal growth factor receptor 2 (HER2) status is not known. This group of patients has not been studied in the available randomized trials. The objective of this study was to evaluate the survival of patients in a monoethnic group diagnosed with T1b lymph node-negative breast cancer depending on HER2 status.

METHODS

We analyzed 3110 patients with T1bN0M0 breast cancer whose data were deposited into the Korean Breast Cancer Society Registry database between 2000 and 2009. Overall survival (OS) and breast cancer-specific survival (BCSS) were compared according to HER2 status.

RESULTS

Among all patients, 494 (15.9%) had HER2-positive breast cancer. At a mean follow-up of 93 months, 108 deaths and 86 breast cancer-specific deaths were noted among all patients. There was no significant difference in OS between the HER2-negative and HER2-positive groups (p = 0.103). The same result was observed for BCSS. However, in the subgroup of estrogen receptor (ER)-positive women, HER2-negative patients had a better BCSS prognosis than HER2-positive patients (p = 0.025). Multivariate analysis also indicated a significant difference in BCSS in the ER-positive subgroup (HR 2.60; 95% CI 1.15-5.87; p = 0.021).

CONCLUSION

This study analyzed a large nationwide and monoethnic cohort and found a significant difference only in BCSS in the ER-positive subgroup according to HER2 status. Anti-HER2 therapy may be considered in HER2-positive and ER-positive patients with small, node-negative breast cancer.

Association of Insulin, Metformin, and Statin with Mortality in Breast Cancer Patients

PURPOSE

This study investigated the association of insulin, metformin, and statin use with survival and whether the association was modified by the hormone receptor status of the tumor in patients with breast cancer.

MATERIALS AND METHODS

We studied 7,452 patients who had undergone surgery for breast cancer at Seoul National University Hospital from 2008 to 2015 using the nationwide claims database. Exposure was defined as a recorded prescription of each drug within 12 months before the diagnosis of breast cancer.

RESULTS

Patients with prior insulin or statin use were more likely to be older than 50 years at diagnosis and had a higher comorbidity index than those without it (p < 0.01 for both). The hazard ratio (HR) for death with insulin use was 5.7 (p < 0.01), and the effect was attenuated with both insulin and metformin exposure with an HR of 1.2 (p=0.60). In the subgroup analyses, a heightened risk of death with insulin was further prominent with an HR of 17.9 (p < 0.01) and was offset by co-administration of metformin with an HR of 1.3 (p=0.67) in patients with estrogen receptor (ER)-negative breast cancer. Statin use was associated with increased overall mortality only in patients with ER-positive breast cancer with HR for death of 1.5 (p=0.05).

CONCLUSION

Insulin or statin use before the diagnosis of breast cancer was associated with an increase in all-cause mortality. Subsequent analyses suggested that metformin or statin use may have been protective in patients with ER-negative disease, which warrants further studies.

Accuracy of Post-Neoadjuvant Chemotherapy Image-Guided Breast Biopsy to Predict Residual Cancer

Importance

Image-guided breast biopsy of a residual imaging abnormality or tumor bed after neoadjuvant chemotherapy (NACT) is increasingly used to assess residual cancer, facilitate risk-adaptive surgery, and potentially identify exceptional responders in whom local therapy may be de-escalated.

Objective

To further assess the accuracy of post-NACT image-guided biopsy to predict residual cancer in the breast.

Design, Setting, and Participants

This diagnostic study analyzed multicenter patient-level data of patients with breast cancer who were treated with NACT and underwent image-guided biopsy before surgery at Royal Marsden Hospital in London, UK; Seoul National University Hospital in Seoul, South Korea; and MD Anderson Cancer Center in Houston, Texas. Data were analyzed from June to July 2019.

Main Outcomes and Measures

Diagnostic accuracy of post-NACT image-guided biopsy. Final surgical pathology was used as reference standard.

Results

Data from 166 women were analyzed. The median (range) age was 49 (25-76) years. The median (range) tumor size on pretreatment and posttreatment imaging was 33.5 (12-100) mm and 10 (0-100) mm, respectively. The overall pathologic complete response rate was 51.2% (n = 85) (16.1% [5 of 31] for hormone receptor-positive/ERBB2 (formerly HER2)-negative; 44.7% [21 of 47] for hormone receptor-positive/ERBB2-positive; 69% [20 of 29] for hormone receptor-negative/ERBB2-positive; and 66.1% [39 of 59] for triple negative). The majority (143 [86.1%]) underwent image-guided vacuum-assisted biopsy (VAB), and 23 had core-cut biopsy. The median (range) needle gauge was 10 (7-14), and the median (range) number of samples was 6 (2-18). When image-guided biopsy (VAB and core-cut biopsy) was representative (159 [95.8%]), the false-negative rate across the whole cohort was 18.7% (95% CI, 10.6%-29.3%). Subgroup analysis of patients with a complete/partial clinical response and residual imaging abnormality of 2 cm or smaller with at least 6 VABs taken (76 [45.8%]) demonstrated a false-negative rate of 3.2% (95% CI, 0.1%-16.7%), a negative predictive value of 97.4% (95% CI, 86.5%-99.9%), and an overall accuracy of 89.5% (95% CI, 80.3%-95.3%).

Conclusions and Relevance

This large multicenter pooled data analysis suggests that a standardized protocol using image-guided VAB of a tumor bed measuring 2 cm or smaller with 6 or more representative samples allows reliable prediction of residual disease. These results could inform the design of de-escalation trials in NACT exceptional responders testing the safety of eliminating surgery.

Identification of breast cancer patients with pathologic complete response in the breast after neoadjuvant systemic treatment by an intelligent vacuum-assisted biopsy

BACKGROUND

Neoadjuvant systemic treatment elicits a pathologic complete response (pCR) in about 35% of women with breast cancer. In such cases, breast surgery may be considered overtreatment. We evaluated multivariate algorithms using patient, tumor, and vacuum-assisted biopsy (VAB) variables to identify patients with breast pCR.

METHODS

We developed and tested four multivariate algorithms: a logistic regression with elastic net penalty, an Extreme Gradient Boosting (XGBoost) tree, Support Vector Machines (SVM), and neural network. We used data from 457 women, randomly partitioned into training and test set (2:1), enrolled in three trials with stage 1-3 breast cancer, undergoing VAB before surgery. False-negative rate (FNR) and specificity were the main outcome measures. The best performing algorithm was validated in an independent fourth trial.

RESULTS

In the test set (n = 152), the logistic regression with elastic net penalty, XGboost tree, SVM, and neural network revealed an FNR of 1.2% (1 of 85 patients with missed residual cancer). Specificity of the logistic regression with elastic net penalty was 52.2% (35 of 67 women with surgically confirmed breast pCR identified), of the XGBoost tree 55.2% (37 of 67), of SVM 62.7% (42 of 67), and of the neural network 67.2% (45 of 67). External validation (n = 50) of the neural network showed an FNR of 0% (0 of 27) and a specificity of 65.2% (15 of 23). Area under the ROC curve for the neural network was 0.97 (95% CI, 0.94-1.00).

CONCLUSION

A multivariate algorithm can accurately select breast cancer patients without residual cancer after neoadjuvant treatment.

Interaction of Nrf2 with dimeric STAT3 induces IL-23 expression: Implications for breast cancer progression

Persistent activation of STAT3 and Nrf2 is considered to stimulate the aggressive behavior of basal-like breast cancer (BLBC). However, the precise mechanism underlying sustained overactivation of these transcription factors and their roles in breast cancer progression remain elusive. Analysis of the TCGA multi-omics data showed that high levels of STAT3 and Nrf2 mRNA were correlated with elevated expression of P-STAT3^Y705 and Nrf2 target proteins in breast cancer patients. Our present study demonstrates a unique interaction between Nrf2 and STAT3 in the maintenance and progression of BLBC. RNA sequencing analysis identified the gene encoding IL-23A upregulated by concurrent binding of STAT3 and Nrf2 to its promoter. IL-23A depletion also showed the similar phenotypic changes to those caused by double knockdown of both transcription factors. In conclusion, the STAT3-Nrf2 interaction accelerates BLBC growth and progression by augmenting IL-23A expression, which underscores the importance of subtype-specific molecular pathways in human breast cancer.