HER2 Type Breast Cancer Research Articles

Abstract P2-20-04: Vaccination against HIF1α/c-MET peptides overcome lapatinib resistance and inhibits tumor growth by immunomodulating in HER2 positive breast cancer

Abstract Human Epidermal growth factor Receptor 2 (HER2) is overexpressed in 20% to 30% of breast cancers and is associated with poor prognosis. Patients with advanced HER2-type breast cancer are treated with HER2-directed tyrosine kinase inhibitors as well as antibodies, but many patients finally acquire therapeutic resistance. Therefore, it is important to develop new treatment strategies that circumvent HER2 positive resistant breast cancer. Among the suggested mechanisms of resistance to HER2-targeted therapeutics, tumor hypoxia and relevant biological factors are known as important players. In this study, we aimed to explore the role of tumor hypoxia in the development of resistance to HER2-targeted therapeutics, and whether the role of an immunological therapy targeting this could contribute to overcoming resistance. To this end, we established lapatinib-resistant HER2 positive breast cancer cells in vitro (SKBR3, BT-474 for human and MMC for murine cells). First, we examined if lapatinib-sensitivity is different according to oxygen concentration using lapatinib-resistant cell lines (LR-SKBT3, LR-BT-474, LR-MMC) compared with parent cell lines. Resistant cells were resistant both in normoxic and hypoxic conditions, but parent cells were highly sensitive in both of the oxygen concentration. In the Western blot analysis, HIF1α and c-MET were overexpressed in the resistant cells compared with parent cell lines in both normoxic and hypoxic condition. Interestingly, treatment with lapatinib had reduced HIF1α and c-MET expression at normoxia in parent cell lines but not in resistant cell lines. Under the hypoxic conditions, the difference in expression of HIF1α and c-MET was more pronounced between parent cell lines and resistant cell lines treated with lapatinib. These results indicate that the expression of HIF1α and c-MET was involved in lapatinib-resistant. In a previous study, we have identified epitopes from HIF1α/c-MET and demonstrated effect of delayed bone metastasis in triple negative breast cancer model when used as peptide vaccine. Herein, we evaluated whether the immunization using HIF1α/c-MET peptide vaccine is effective in inhibition of lapatinib-resistant HER2 positive breast cancer growth in vivo. MMTVneu-transgenic mouse model was used and 6- 8 weeks old mice were injected with LR-MMC subcutaneously. Immunization using the HIF1α/c-MET peptide vaccine significantly inhibited growth of LR-MMC cells in MMTVneu-transgenic mice compared with controls. HIF1α/c-MET specific IFN-γ-secreting T cell responses in the splenocytes were significantly higher in the immunized group than controls. Immunohistochemical staining of T cells revealed that expression of tumor HIF1α and c-MET was significantly decreased, while the number of CD8+ T cell was increased in the tumors from immunized animals compared with control tumors. In conclusion, our study demonstrated that the vaccine targeting HIF1α/c-MET might be a promising cancer immunotherapy in lapatinib-resistant HER2 positive breast cancer. In vivo study to evaluate efficacy of combination therapy (lapatinib and HIF1α/c-MET vaccine) is ongoing. Citation Format: Ji Min Lee, Jin Hwa Hong, Soon Young Lim, Ju Won Kim, Ah Reum Lim, Myung Han Hyun, Kyong Hwa Park. Vaccination against HIF1α/c-MET peptides overcome lapatinib resistance and inhibits tumor growth by immunomodulating in HER2 positive breast cancer. [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P2-20-04.

Determining the Factors Predicting the Response to Anti-HER2 Therapy in HER2-Positive Breast Cancer Patients.

We aimed to identify the differently expressed genes or related pathways associated with good responses to anti-HER2 therapy and to suggest a model for predicting drug response in neoadjuvant systemic therapy with trastuzumab in HER2-positive breast cancer patients. This study was retrospectively analyzed from consecutively collected patient data. We recruited 64 women with breast cancer and categorized them into 3 groups: complete response (CR), partial response (PR), and drug resistance (DR). The final number of patients in the study was 20. RNA from 20 core needle biopsy paraffin-embedded tissues and 4 cultured cell lines (SKBR3 and BT474 breast cancer parent cells and cultured resistant cells) was extracted, reverse transcribed, and subjected to GeneChip array analysis. The obtained data were analyzed using Gene Ontology, Kyoto Gene and Genome Encyclopedia, Database for Annotation, Visualization and Integrated Discovery. In total, 6,656 genes differentially expressed between trastuzumab-susceptible and trastuzumab-resistant cell lines were identified. Among these, 3,224 were upregulated and 3,432 were downregulated. Expression changes in 34 genes in several pathways were found to be related to the response to trastuzumab-containing treatment in HER2-type breast cancer, interfering with adhesion to other cells or tissues (focal adhesion) and regulating extracellular matrix interactions and phagosome action. Thus, decreased tumor invasiveness and enhanced drug effects might be the mechanisms explaining the better drug response in the CR group. This multigene assay-based study provides insights into breast cancer signaling and possible predictions of therapeutic response to targeted therapies such as trastuzumab.

Nicotine treatment regulates PD-L1 and PD-L2 expression via inhibition of Akt pathway in HER2-type breast cancer cells.

The immune checkpoint molecules such as PD-L1 and PD-L2 have a substantial contribution to cancer immunotherapy including breast cancer. Microarray expression profiling identified several molecular subtypes, namely luminal-type (with a good-prognosis), HER2-type (with an intermediate-prognosis), and triple-negative breast cancer (TNBC)-type (with a poor-prognosis). We found that PD-L1 and PD-L2 mRNA expressions were highly expressed in TNBC-type cell lines (HCC1937, MDA-MB-231), moderately expressed in HER2-type cell line (SK-BR-3), and poorly expressed in luminal-type cell lines (MDA-MB-361, MCF7). The PD-L1 and PD-L2 expression in SK-BR-3 cells, but not those in HCC1937 and MDA-MB-231 cells, decreased by nicotine stimulation in a dose-dependent manner. In addition, nicotine treatment decreased the phosphorylation of Akt in SK-BR-3 cells, but not in other cell lines. These results show that nicotine regulates the expression of immune checkpoint molecules, PD-L1 and PD-L2, via inhibition of Akt phosphorylation. This findings may provide the new therapeutic strategies for the treatment of breast cancer.

Glucose and glutamine metabolism-related protein expression in breast ductal carcinoma in situ.

Glucose and glutamine metabolism is involved in important tumor mechanisms. Metabolism-related protein expression has been previously reported to predict tumor prognosis. We aimed to investigate glucose and glutamine metabolism-related protein expression and its implication in breast ductal carcinoma in situ (DCIS). A tissue microarray was prepared for 205 DCIS cases. Glucose and glutamine metabolism-related proteins were immunostained. Based on the results of estrogen receptor, progesterone receptor, human epidermal growth factor receptor (HER)-2, and Ki-67, DCIS was classified into the luminal type, HER-2 type, and triple-negative breast cancer (TNBC). DCIS stroma was classified into non-inflammatory and inflammatory types per stromal histology. DCIS (N=205) was classified into luminal type (n=112), HER-2 type (n=81), and TNBC (n=12). Hexokinase II (p=0.044), GLS (p=0.003), and SLC7A5 (p<0.001) expression rates were the highest in TNBC. Inflammatory type stroma showed higher SLC7A5 (p<0.001) and SLC7A11 (p=0.008) expression rates than non-inflammatory type stroma. In summary, DCIS demonstrated differential expression of metabolism-related proteins according to the molecular subtype and stromal features. TNBC showed the highest glucose and glutamine metabolism-related protein expression, and inflammatory type stroma showed higher glutamine metabolism-related protein expression than non-inflammatory type stroma.

Oxytocin receptor induces mammary tumorigenesis through prolactin/p-STAT5 pathway

Oxytocin receptor (OXTR) is involved in social behaviors, thermoregulation, and milk ejection, yet little is known about its role in breast cancer. To investigate the role of OXTR in mammary gland development and tumorigenesis, a transgenic mouse model of OXTR overexpression (++Oxtr) was used. Overexpression of OXTR-induced progressive mammary hyperplasia, unexpected milk production, and tumorigenesis in females. OXTR-induced mammary tumors showed ERBB2 upregulation and mixed histological subtypes with predomination of papillary and medullary carcinomas. OXTR overexpression led to an activation of prolactin (PRL)/p-STAT5 pathway and created a microenvironment that promotes mammary-specific tumorigenesis. PRL inhibitor bromocriptine (Br) could mitigate OXTR-driven mammary tumor growth. The study demonstrates Oxtr is an oncogene and a potential drug target for HER2-type breast cancer.

Axillary Sampling as an Alternative Option for Complete Nodal Response in Triple Negative and HER2 Type Breast Cancer Patients after Neoadjuvant Chemotherapy

Axillary Sampling as an Alternative Option for Complete Nodal Response in Triple Negative and HER2 Type Breast Cancer Patients after Neoadjuvant Chemotherapy

Abstract PO-200: Increased risk of luminal A and HER2-type breast cancer with lifetime cigarette smoking among non-Hispanic Black and White women in the Young Women’s Health History Study

Abstract Previous studies have found that tobacco exposure is associated with an increased risk of premenopausal breast cancer (BC) overall and some studies suggest that risk is only increased for Luminal A BC. Few studies have described the association between tobacco exposure and BC risk with characterization of the human epidermal growth factor receptor 2 (HER2) subtype. This analysis explored associations between smoking over the life course and BC risk overall and by BC subtype among a socioeconomically diverse population of young non-Hispanic (NH) Black and White women. Data were examined from a population-based case-control study in women under 50 years of age, the Young Women’s Health History Study. In total, 1,812 women with invasive BC (1,130 NH White, 682 NH Black) and an area-based sample of 1,381 (716 NH White, 665 NH Black) control women, frequency matched to cases by five-year age group, study site and self-reported race were identified from the Los Angeles County and Metropolitan Detroit SEER registry areas. Lifetime smoking histories were collected from in-person interviews. Sample-weighted logistic regression analysis was conducted to estimate the association between lifetime cigarette smoking status (never versus ever smoker) and BC risk adjusted for known BC risk factors and study site. Multinomial logistic regression analysis was conducted for analyses by BC subtype. Heterogeneity in the odds ratio (OR) estimates by BC subtype and cross-product interaction terms of smoking status by race and by household percent poverty (HHP) were evaluated by the Wald test. In adjusted models, BC risk overall was not significantly associated with ever smoking at least 1 cigarette a day for 6 months or more (OR 1.18; 95% confidence interval (CI) 0.97- 1.43). By BC subtype, ever smokers displayed a statistically significant 30% increase in Luminal A BC risk compared to never smokers (OR 1.30; 95% CI 1.03-1.64) and a 90% increased risk of HER2-type BC (OR 1.90; 95% CI 1.17-3.08). Smoking was not associated with risk of Luminal B or Triple Negative BC. Associations between ever smoking and BC risk significantly differed by BC subtype (Pheterogeneity=0.02). Statistical interactions by race or by HHP were not observed. However, we noted that in stratified models the association between smoking and risk for HER2-type BC was higher among NH White compared to NH Black women and among women with HHP ≥150% compared to HHP &amp;lt;150%. For Luminal A BC, the association with smoking did not differ by race and risk was higher among women with HHP &amp;lt;150% compared to HHP ≥150%. Although other studies have identified an association between smoking and Luminal A BC, this may be the first study to identify an association between smoking and hormone receptor negative, HER2-type BC risk. An increased risk for HER2-type BC among NH White women and women with HHP ≥150% was suggested. Research in HER2-type BC is a relatively new and evolving field as HER2 expression was often underreported in the pathology reports of cases diagnosed before 2005. Citation Format: Ugonna N. Ihenacho, Ann S. Hamilton, Wendy J. Mack, Anna H. Wu, Jennifer B. Unger, Dorothy R. Pathak, Richard T. Houang, Michael F. Press, Kendra L. Schwartz, Lydia Marcus, Ellen M. Velie. Increased risk of luminal A and HER2-type breast cancer with lifetime cigarette smoking among non-Hispanic Black and White women in the Young Women’s Health History Study [abstract]. In: Proceedings of the AACR Virtual Conference: Thirteenth AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2020 Oct 2-4. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2020;29(12 Suppl):Abstract nr PO-200.

Abstract PO-174: Racial and socioeconomic disparities in height and body size in adolescence and risk for breast cancer subtypes in the Young Women’s Health History Study

Abstract The etiology of breast cancer (BC) appears to vary by tumor subtypes and currently, in the United States, non-Hispanic White (NHW) women are at an increased risk for luminal A BC and non-Hispanic-Black (NHB) women are at an increased risk for triple negative (TN) BC. Adolescence is a sensitive time for breast development, and childhood overweight/obesity and short height are associated with lower risk of premenopausal BC. The role of adolescent body size on BC risk by subtype, however, has not been well-studied. Relative to NHW girls and girls with higher socioeconomic position (SEP), NHB girls and those with lower SEP are at increased risk of overweight/obesity throughout life. We examined the association between height and body size in adolescence and odds of BC subtypes and the distribution of these factors by self-reported race and SEP. Data are from the Young Women’s Health History Study, a population-based case-control (case n=1812; control n=1381) study of invasive BC among NHB and NHW women aged 20-49 years. BC was diagnosed in Metro Detroit and Los Angeles County SEER registries, 2010-2015. Tumors were classified as luminal A, luminal B, HER2-type, or TN based on estrogen, progesterone, and HER2 receptor status and tumor grade. Area-based controls were frequency matched to cases on site, race and age. During in-home interviews, participants recalled body size at age 12 years with somatotypes (6 levels), weight at age 18 years (used to calculate body mass index (BMI)), and both measured and recalled adult height (&amp;lt;64, 65-66, &amp;gt;67 inches). Data were also collected on self-reported race, adult SEP (household percent poverty (HHP)), and established BC risk factors to evaluate confounding. Adjusted weighted logistic regression was used to calculate odds ratios (OR) and 95% confidence intervals (CIs) of BC subtype (vs controls). We also examined potential interactions with race and SEP. Among controls, NHB women and women with lower SEP (&amp;lt;150% HHP) were more likely to report a higher age 12 somatotype (SEP X2 p=0.02; race X2 p=0.08) and age 18 BMI (SEP X2 p&amp;lt;0.01; race X2 p&amp;lt;0.01); height did not vary by race or SEP. For age 12 somatotype a trend for reduced odds with increased somatotype was observed for Luminal B BC (p=0.05) and potentially TN (p=0.08). Women with age 18 BMI &amp;gt;30 vs 18.5-&amp;lt;25 kg/m2 had lower odds of luminal A (OR=0.43, 95% CI 0.22, 0.87); women with age 18 BMI &amp;lt;18.5 vs 18.5-&amp;lt;25 kg/m2 had increased odds of HER2-type BC (OR=1.85, 95% CI 1.03, 3.32). Taller height (&amp;gt;67 vs 65-66 inches), was associated with increased odds of all BC subtypes, most strongly for HER2-type (OR=1.80, 95% CI: 1.07, 3.03) and TN (OR=1.42, 95% CI: 0.98, 2.07) BC. The effect of these three body size measures on BC subtype risk did not vary by race or SEP. Body size in adolescence appears to be associated with risk for some BC subtypes, perhaps through hormonal mechanisms, and may partially contribute to explanations for racial and SEP disparities. Citation Format: Lydia R. Marcus, Dorothy P. Pathak, Ann S. Hamilton, Kendra L. Schwartz, Richard Houang, Dan A. Sanfelippo, Ellen M. Velie. Racial and socioeconomic disparities in height and body size in adolescence and risk for breast cancer subtypes in the Young Women’s Health History Study [abstract]. In: Proceedings of the AACR Virtual Conference: Thirteenth AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2020 Oct 2-4. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2020;29(12 Suppl):Abstract nr PO-174.

Modelling the structural and reactivity landscapes of tucatinib with special reference to its wavefunction-dependent properties and screening for potential antiviral activity.

HER-2 type breast cancer is one of the most aggressive malignancies found in women. Tucatinib is recently developed and approved as a potential medicine to fight this disease. In this manuscript, we present the gross structural features of this compound and its reactivity and wave function properties using computational simulations. Density functional theory was used to optimise the ground state geometry of the molecule and molecular docking was used to predict biological activity. As the electrons interact with electromagnetic radiations, electronic excitations between different energy levels are analysed in detail using time-dependent density functional theory. Various intermolecular and intermolecular interactions are analysed and reaction sites for attacking electrophiles and nucleophiles identified. Information entropy calculations show that the compound is inherently stable. Docking with COVID-19 proteins show docking score of − 9.42, − 8.93, − 8.45 and − 8.32 kcal/mol respectively indicating high interaction between the drug and proteins. Hence, this is an ideal candidate to study repurposing of existing drugs to combat the pandemic.Supplementary InformationThe online version contains supplementary material available at 10.1007/s00894-020-04603-1.

Abstract 17: MBQ-167, a Rac/Cdc42 targeted therapeutic, in combination with paclitaxel for TNBC treatment

Abstract Triple-negative breast cancer (TNBC) is an aggressive form of breast cancer, with a high predisposition for locally advanced and metastatic cancer. While targeted therapies for TNBC are in various stages of development, current standard chemotherapies include taxanes such as paclitaxel and anthracycline agents. With the objective of specifically targeting invasive cancer, our group has been developing small-molecule inhibitors of the Rho GTPases Rac and Cdc42, which are known drivers of cancer cell invasion and metastasis. Of these, MBQ-167 inhibits both Rac and Cdc42 with IC50s of 103 and 78 nmol/L, respectively, and consequently inhibits p21-activated kinase (PAK) signaling, metastatic cancer cell proliferation, migration, tumor growth, and metastasis (Humphries-Bickley et al., Mol Cancer Ther 2017). We found that in addition to blocking HER2-type breast cancer progression, MBQ-167 is also highly effective against TNBC cell and tumor growth, as well as metastasis in mouse models. The purpose of this study was to test the efficacy of MBQ-167 in combination with the current chemotherapeutic paclitaxel. We hypothesized that the combination of paclitaxel and MBQ-167 is a rational strategy to inhibit tumor growth and metastasis in TNBC. To test this hypothesis, we administered a nontoxic dosage of individual MBQ-167, paclitaxel, or combined MBQ-167 and paclitaxel to immunocompromised mice bearing mammary fat pad tumors from GFP-tagged MDA-MB-468 or MDA-MB-231 human TNBC cells. Tumor growth was monitored weekly and metastasis was quantified at the end of the study. Treatment with MBQ-167 and/or paclitaxel resulted in reduced tumor growth by 70-80% in both models. In the MDA-MB-231 model, MBQ-167 paralleled paclitaxel treatment with a modest benefit in combined therapy. However, in the epidermal growth factor receptor (EGFR)-positive TNBC model MDA-MB-468, MBQ-167 alone or in combination significantly reduced metastasis to the lungs and spleen, while paclitaxel alone increased metastasis to the liver, lungs, and spleen. These results show that MBQ-167 is a promising antimetastatic agent that can be effective in combination with current chemotherapeutic agents. Citation Format: Jean Ruiz-Calderon, Irmaris Lopez-Lopez, Ailed Cruz-Collazo, Suranganie Dharmawardhane. MBQ-167, a Rac/Cdc42 targeted therapeutic, in combination with paclitaxel for TNBC treatment [abstract]. In: Proceedings of the AACR Special Conference on Advancing Precision Medicine Drug Development: Incorporation of Real-World Data and Other Novel Strategies; Jan 9-12, 2020; San Diego, CA. Philadelphia (PA): AACR; Clin Cancer Res 2020;26(12_Suppl_1):Abstract nr 17.

Can sentinel node biopsy after neoadjuvant systemic chemotherapy (NAC) be safely omitted in selected patient with early breast cancer?

564 Background: There is a recent trend of performing minimum axillary surgery considering the prognostic value and fewer complications for primary breast cancer patients since the results of ACOSOG Z011. Nodal status after NAC is not be useful for postoperative treatment in most of cN0 patients. Therefore, sentinel node biopsy (SNB) may be omitted if ypN0 after NAC can be predicted in cN0 patients. We assessed clinicopathological factors associated with ypN0 after NAC in cN0 primary breast cancer patients. Methods: Two-institutional retrospective cohort study of clinically N0 breast cancer patients before NAC and who underwent breast surgery was conducted, including 419 consecutive patients between 2009 and 2016 in St. Luke's International Hospital and St. Marianna University School of Medicine hospital. Each institutional review board approved this study. In the patients with or without nodal metastasis on SNB after NAC, we compared clinicopathological factors including Estrogen Receptor (ER), Progesterone Receptor (PgR), human epidermal growth factor receptor 2 (HER2), Ki-67 on needle biopsy specimens, and tumor size before and after NAC on MRI findings. Results: Of the 419 patients, 380 patients (90.7%) were ypN0 and 39 patients (9.3%) were ypN+ after NAC. In univariate analysis, clinical complete response of primary tumor on MRI findings (MRI-CR) (p&lt;0.01), ER-negative (p&lt;0.01), PgR-negative (p&lt;0.01), and high-Ki-67 &gt;30% (p&lt;0.01) were significantly associated with ypN0 on SNB after NAC. In multivariate analysis, MRI-CR (HR 5.12, p&lt;0.01) and high-Ki-67 (HR 2.86, p&lt;0.01) were independent predictive factors of ypN0 after NAC.According to breast cancer subtype, only one of 72 ER-negative and HER2-positive had significantly low risk of ypN+ (1.3%) comparing other subtypes (p&lt;0.01). Conclusions: Achieving cCR of primary tumor after NAC and high-Ki67 in cN0 patients, especially in HER2 type breast cancer, might have ypN0. We are conducting prospective study to omit SNB for these populations based on these results,

Precision cell-free DNA extraction for liquid biopsy by integrated microfluidics

Cell-free DNA (cfDNA) has been implicated as an important biomarker in cancer management. Thus, efficient techniques for cfDNA extraction are necessary for precision medicine. We developed a centrifugation-free cfDNA extraction microfluidic chip capable of extracting cfDNA from plasma samples through microfluidic circuits within 15 min under vacuum pressure using an immiscible solvent. The microfluidic chip had excellent performance that was comparable to the most widely used commercial product (QIAamp kit) in terms of extraction efficiency, purity, and quality of DNA samples. The microfluidic chip was validated for the continuous monitoring of HER-2 type breast cancer and was able to successfully detect a point mutation in phosphatidylinositol-4,5-bisphosphate 3-kinase (PIK3CA) during severe liver metastasis. The chip effectively eliminates the repetitive centrifugation processes and dramatically shortened the sample preparation time. The proposed platform could facilitate the development of a sample-to-answer system for use in liquid biopsy of cancers.

HER2 Type Male Breast Cancer Successfully Treated with Pertuzumab, Trastuzumab, and Eribulin Therapy: A Case Report

Background: Male breast cancer is rare, accounting for approximately 0.5% - 1.0% of all breast cancer cases; hormone-dependent luminal type male breast cancer is the most common. The proportion of hormone receptor-negative and human epithelial growth factor Receptor type 2-positive breast cancer is extremely low among male breast cancer. A patient with advanced HER2 type breast cancer, a rare male breast cancer, was successfully treated with pertuzumab, trastuzumab, and eribulin therapy. Case Presentation: A 75- year-old man presented to our hospital with induration of the right anterior chest and lymphoedema of the right upper limb. Based on the results of core needle biopsy, he was diagnosed with HER2 type invasive ductal carcinoma associated with bone metastasis (stage IV). Chemotherapy with pertuzumab, trastuzumab, and eribulin was started. The drugs were remarkably effective, and his lymphoedema tended to improve. Conclusion: We reported a successful case of chemotherapy and targeted therapy for a rare male breast cancer of HER2 positive and hormone negative type.

Clinical and pathological predictors of recurrence in breast cancer patients achieving pathological complete response to neoadjuvant chemotherapy

IntroductionDespite the excellent prognosis associated with pathological complete response (pCR) to neoadjuvant chemotherapy (NAC), some patients still develop recurrence. Here, we investigated the outcomes of breast cancer patients with pCR, as well as the clinical and pathological predictors of cancer recurrence in these patients. Materials and methodsOf the 1599 breast cancer patients treated with NAC, we evaluated 394 patients who achieved pCR between January 2007 and December 2016. pCR was defined as no evidence of invasive cancer in breast. Residual in situ ductal and axillary lymph node diseases were not considered. We analyzed the outcomes using the Kaplan–Meier method. We assessed the association of clinical and pathological predictors with cancer recurrence using the cox proportional hazards regression model. ResultsThe median follow-up time was 63 months. The 5-year disease-free survival rate was 92.3%. Cancer recurrence was observed in 28 patients (7.1%): local recurrence 8 patients (2.0%), visceral metastasis 10 patients (2.5%), and brain metastasis 10 patients (2.5%). Brain metastases were found in patients with HER2 type breast cancer. The significant predictors of cancer recurrence were HER2 positivity (p = 0.04), clinical tumor size (p < 0.01), and lymph node metastasis (p < 0.01) before NAC on univariate analysis and only lymph node metastasis on multivariate analysis. ConclusionPatients achieving pCR to NAC showed excellent outcomes. Advanced clinical stage, large tumor size, presence of lymph node metastasis, and HER2 positivity before NAC were identified as significant predictors of cancer recurrence. Residual in situ ductal and lymph node diseases after NAC were not significant predictors.

Abstract 5635: The development to peptide vaccine targeting heat shock protein 90 to overcome resistance to HER-2 target drugs in breast cancer

Abstract HER-2 overexpression is observed in approximately 25% of all breast cancers and is associated with poorer overall survival and decreased time to relapse. Target therapies directed against HER-2 have been developed and used clinically, but many patients continue to develop resistance. Breast cancer is immunogenic and well suited to treatment via immunomodulation. HSP90 is a chaperon for most of the important signal transduction system in HER-2 type breast cancer; HER-2, ER / PR and Akt, the downstream protein of PI3K. Therefore, HSP90 is considered as a potential therapeutic target in order to improved treatment of HER-2 positive resistant breast cancer. Immunotherapy targeting HSP90 has been tried before, however, no clinically available vaccine due to limitation of autologous cell-based approach. We questioned whether HSP90 was an immune target in HER-2 positive breast cancer. First, HSP90-specific IgG antibody immunity was detected in the sera from HER-2 positive breast cancer patients. Next, potential MHC class II epitopes derived from HSP90 with high binding affinity across multiple human HLA genotypes were identified using in silico algorithms. Top 11 peptides were synthesized and Th1 vs Th2 immunity were assessed in human PBMCs. After IFN-γ and IL-10 ELISPOT assays, epitopes inducing Th1-directed immunity were selected for in vivo experiments. Immunogenecity of HSP90 peptides vaccine was evaluated in FVB mice model and showed strong antigen-specific T cell responses in IFN-γ ELISPOT assay. Then, we assessed the anti-tumor effect of immunization with HSP90 peptides vaccine in MMTV-neu-transgenic mouse model after autologous cancer cell implantation. Peptides vaccines derived from HSP90 significantly inhibited tumor growth compared with control group (mean ± SD; 1896 ± 1211 mm3 vs. mean ± SD; 774 ± 136 mm3, respectively; p &amp;lt; 0.05). The tumor-inhibitory effect was associated with HSP90 peptide-specific IFN-γ-secreting T cell responses in immunization group. Also, immunohistochemical staining of tumors derived from immunized mice was performed to examine immune microenvironment and the protein expression of HER-2 pathways. Taken together, multi-epitope peptides vaccine derived from HSP90 is immunogenic in breast cancer patients and is a promising tumor antigen. Based on efficacies in tumor-rejection in vivo, further research in combination with immune modulating antibodies will be performed in the lapatinib-resistant tumor model. Citation Format: Jinho Kang. The development to peptide vaccine targeting heat shock protein 90 to overcome resistance to HER-2 target drugs in breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 5635.

Immune response induced by preoperative chemotherapy in breast cancer: Role of peripheral natural killer (pNK) cell activity, tumor-infiltrating lymphocytes (TILs), and tumor microenvironment factors (TMEFs).

e12644Background: TILs are predictive and prognostic factors in HER2 type and triple negative breast cancer patients undergoing neoadjuvant chemotherapy. NK cells exert innate immunity, a decrease ...

333 (PB-128) - Effectiveness of Neo-Adjuvant Systemic Therapy for Basal HER2 type Breast Cancer – Results from Retrospective Cohort Study of Japan Breast Cancer Research Group (JBCRG) – C03

333 (PB-128) - Effectiveness of Neo-Adjuvant Systemic Therapy for Basal HER2 type Breast Cancer – Results from Retrospective Cohort Study of Japan Breast Cancer Research Group (JBCRG) – C03

Abstract B094: The dual Rac/Cdc42 inhibitor MBQ-167 and derivatives as anticancer compounds

Abstract Metastatic disease lacks effective treatments, and remains the primary cause of mortality from epithelial cancers. The Rho family GTPases Rac and Cdc42 and their downstream effector p21-activated kinase (PAK) are pivotal regulators of metastatic cancer cell migration and invasion; thus, overexpression of Rac/Cdc42/PAK has been correlated with reduced patient survival in breast, gastric, and lung cancer. Our studies on the efficacy and pharmacokinetics of the Rac inhibitor EHop-016 (US patents # 8,884,006 B2; 9,278,956B1) validated the development of Rac and Cdc42 inhibitors as anti-metastatic cancer therapeutics. To improve the pharmacologic utility of EHop-016, structural derivatives were screened for enhanced efficacy and bioavailability. We recently identified a dual Rac and Cdc42 inhibitor, MetaBloq(MBQ)-167, which inhibits Rac and Cdc42 activation with IC50s of 103 nM for Rac inhibition and 78 nM for Cdc42 inhibition. Moreover, MBQ-167 is specific to cancer cells that have undergone epithelial-to-mesenchymal transition (EMT), but not epithelial cancer cells or noncancer cells. In metastatic cancer cells, MBQ-167 induces a unique phenotype of loss in cell polarity, cell surface actin extensions, and cell-substrate attachments to undergo anoikis (apoptosis due to inadequate cell-matrix interactions). In vivo, MBQ-167 inhibits HER2 type mammary tumor growth and metastasis in immunocompromised mice by ~90-100% (Humphries-Bickley et al., Mol Cancer Ther 2017; patent applications US 15/499532, PCT/US17/29921). In this study, we have further tested the pharmacokinetics and utility of MBQ-167 in additional models of cancer and screened MBQ-167 derivatives for their utility as Rac/Cdc42 inhibitors. Similar to the results with HER2 type breast cancer, in severe combined immunodeficiency (SCID) mice with mammary fat pad tumors from the triple-negative MDA-MB-231 human breast cancer cell line, the effect of MBQ-167 saturated at 1 mg/kg BW with a 80% reduction in tumor growth and a 100% reduction in metastasis. In gastric cancer, MBQ-167 reduced the viability of metastatic NCI-N87 gastric cancer cells, induced anoikis without affecting the AGS nonmetastatic gastric cancer cells, and inhibited tumor growth in SCID mice. We have screened a range of MBQ-167 derivatives for cell viability and the “anoikis” phenotype and isolated 4 compounds that reduced breast cancer cell viability with GI50s in the nM range. From this screen, MBQ-14 acts similar to MBQ-167, and thus is considered to be a viable inhibitor for further investigation. We have developed a quantitative method for identifying MBQ-167 and MBQ-14 from mouse plasma using ultra-performance convergence chromatography (UPC2)/MS/MS, and find that MBQ-167 is bioavailable in mouse plasma with a half-life of ~4h following oral or intraperitoneal administration. Overall our data demonstrate the utility of further developing MBQ-167 and derivatives as anti-metastatic cancer therapeutics. Citation Format: Linette Castillo-PIchardo, Maria Del Mar Maldonado, Jean Ruiz-Calderon, Jose F. Rodriguez-Orengo, Eliud Hernandez, Cornelis Vlaar, Surangani F. Dharmawardhane Flanagan. The dual Rac/Cdc42 inhibitor MBQ-167 and derivatives as anticancer compounds [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2017 Oct 26-30; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2018;17(1 Suppl):Abstract nr B094.

Abstract 2197: Characterization of immunoliposomes as delivery vehicles for the Rac inhibitor Ehop-016 in HER2 type breast cancer

Abstract Due to the critical need for improved therapeutics against advanced Stage IV breast cancer, we developed and pre-clinically validated the small molecule Ehop-016 as a potential anti-metastatic drug. Ehop-016 is a small molecule inhibitor of the interaction Rac with the guanine nucleotide exchange factor (GEF) Vav2, which consequently decreases invasive actin structures and cellular migration. In a human epidermal growth factor receptor 2 (HER2) type breast cancer model in nude mice, Ehop-016 inhibits mammary tumor growth, angiogenesis, and metastasis. Moreover, Ehop-016 reduces HER2++ cancer cell viability and migration, individually or in combination with anti HER2 or EGFR directed therapeutics. By inhibiting the key signaling intermediate Rac, Ehop-016 has the potential to block signaling downstream of HER2 and EGFRs, as well as signaling via the myriad of receptors that activate Rac, and inhibit cancer progression. Our new results demonstrate that Ehop-016 inhibits both cancer cells and leukocytes in the tumor microenvironment, as well as cytokine levels (IL-6) in mouse plasma. Even though these characteristics are desirable in anticancer agents, systemic therapy with Ehop-016 may adversely affect normal immune system function. Therefore, a strategy was developed for the targeted delivery of Ehop-016 into mammary tumors, using nanoliposomes containing the current breast cancer therapeutic, Trastuzumab, a monoclonal antibody directed at the HER2. We tested various nanoliposome formulations as targeted delivery systems for Ehop-016. First, the encapsulation efficiency of Ehop-016 loaded liposomes was tested using different drug loading methods. To obtain HER2 targeted liposomes, we prepared Trastuzumab-lipid conjugates and incorporated them into the Ehop-016 containing liposomes. The binding, internalization and selectivity of our HER2 targeted delivery system was verified in human metastatic breast cancer cell lines, by using fluorescence microscopy to assess the co-staining of the lipid bilayer and Trastuzumab. In order to evaluate the effectiveness and selectivity of the immunoliposomes in delivering Ehop-016 and inhibiting Rac activity, pull-down assays were performed to detect active Rac-GTP in cells treated with Ehop-016 alone or Trastuzumab-conjugated liposomes with Ehop-016. Results show that the Trastuzumab-conjugated liposomes are more selective at binding to HER2+ breast cancer cells and inhibiting Rac, than treatment with Ehop-016 alone. In summary, our novel delivery system containing Ehop-016 and Trastuzumab has been shown to be effective in breast cancer cells, and needs to be validated in animal models of metastatic breast cancer. The development of this targeted delivery system has implications, not only in the field of breast cancer therapeutics, but may be adapted for the treatment of other diseases, and used to overcome the side effects of current treatments. Citation Format: Michael J. Rivera-Robles, Pablo E. Vivas-Mejia, Linette Castillo-Pichardo, Cornelis Vlaar, Eliud Hernández, Suranganie Dharmawardhane. Characterization of immunoliposomes as delivery vehicles for the Rac inhibitor Ehop-016 in HER2 type breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 2197. doi:10.1158/1538-7445.AM2017-2197

Effect of ALDH1 on prognosis and chemoresistance by breast cancer subtype.

Aldehyde dehydrogenase 1 (ALDH1) has been identified as a breast cancer stem cell marker, but its value as a predictor of prognosis and chemoresistance is controversial. This study investigated the effect of ALDH1 on prognosis and chemoresponse by breast cancer subtype. We immunohistochemically analyzed 653 invasive breast cancer specimens and evaluated correlations among clinicopathological factors, survival status, response to neoadjuvant chemotherapy, and ALDH1 expression. Of 653 specimens, 139 (21.3%) expressed ALDH1 in tumor cells. ALDH1 expression was correlated significantly with larger tumor size, node metastasis, higher nuclear grade, and with HER2(+) and progesterone/estrogen receptor (HR)(-) subtypes. ALDH1 expression was significantly observed in HER2 type and triple-negative breast cancer (TNBC). Patients with ALDH1(+) cancers had significantly shorter disease-free survival (P<0001) and overall survival (P=0.044). ALDH1 expression significantly affected prognosis of luminal types, but not TNBC and HER2-enriched types. For the 234 patients treated with neoadjuvant chemotherapy, pathological complete response (pCR) rate was significantly lower in ALDH1(+) cases (13.5 vs. 30.3%, P=0.003). pCR and ALDH1 expression were significantly correlated in TNBC patients (P=0.003). ALDH1(+) breast cancers tended to be aggressive, with poor prognoses. Although ALDH1(+) TNBC showed higher chemoresistance, ALDH1 had significant impact on prognosis in the luminal type but not in TNBC.