Fibroblast growth factor receptor-1 protein expression is associated with prognosis in estrogen receptor-positive/human epidermal growth factor receptor-2-negative primary breast cancer

Recently, research into the development of new targeted therapies has focused on specific genetic alterations to create advanced, more personalized treatment. One of the target genes, fibroblast growth factor receptor‐1 (FGFR1), has been reported to be amplified in estrogen receptor (ER)‐positive subtype breast cancer, and is considered one possible mechanism of endocrine resistance through cross‐talk between ER and growth factor receptor signaling. We performed a comprehensive analysis of FGFR1 at the levels of gene copy number, transcript and protein expression, and examined the relationships between FGFR1 status and clinicopathological parameters, including prognosis in 307 ER‐positive/HER2‐negative primary breast cancer patients treated with standard care at our institute. Most notably, a high level of FGFR1 protein expression was observed in 85 patients (27.7%), and was positively associated with invasive tumor size (P = 0.039). Furthermore, univariate analysis revealed that high FGFR1 protein expression was significantly correlated with poor relapse‐free survival rate (P = 0.0019, HR: 2.63, 95% confidence interval: 1.17–5.98), and showed a tendency towards an increase in recurrent events if the observation period extended beyond the 5 years of the standard endocrine treatment term. FGFR1 gain/amplification was found in 43 (14.0%) patients, which was only associated with higher nuclear grade (P = 0.010). No correlation was found between FGFR1 mRNA expression levels and any clinicopathological factors. Overall, the level of FGFR1 protein expression may be a biomarker of ER‐positive/HER2‐negative primary breast cancer with possible resistance to standard treatment, and may be a useful tool to identify more specific patients who would benefit from FGFR‐1 targeted therapy.

Abstract P6-07-07: Clinical significance of ESR1 mutations using droplet digital polymerase chain reaction assay in 325 breast cancer samples

Purpose: We aimed to develop a droplet digital Polymerase Chain Reaction (ddPCR)-based method for the sensitive detection of estrogen receptor (ER) α (ESR1) mutations in the primary and recurrent/metastatic tumor tissues of breast cancer.

Experimental Design: We studied a total of 325 tumor specimens (270 primary breast cancer specimens and 55 ER-positive recurrent/metastatic tumor specimens). Because the recurrent/metastatic tumor specimens had much inflammatory and stromal cells, we captured only tumor cells using laser microdissection. We investigated the quantification of rare ESR1 mutations, four representative types, Y537S, Y537N, Y537C, and D538G in extracted genomic DNA using ddPCR system that simultaneously performed thousands of PCRs on a nanoliter scale.

Results: In 270 primary breast cancer samples, we analyzed each ESR1 alteration percentage in each subtype. ESR1 Y537C tended to be higher in hormone receptor-positive (HR+)/ human epidermal growth factor receptor 2-negative (HER2-) group (P = 0.06) and higher percentage of ESR1 D538G was statistically significant in HR+/ HER2- group (P = 0.027), compared with HER2+ group. There was no statistically different in each ESR1 alteration percentage between HR+/ HER2- group and HR-/ HER2- group. Whether each ESR1 alteration was dichotomized as positive or not, we used the percentage which HER2+ group and HR-/ HER2- were not identified, as a cutoff point. ESR1 mutations occurred in 7 samples (2.5%) out of 270 primary samples, but ESR1 mutations occurred in 11 samples (20%) out of 55 metastatic/ recurrent breast cancer samples.

Table 1 Patients characteristics of 11 metastatic ER-positive breast cancer cases with ESR1 mutationsCaseAge (years)HER2 statusKi67 LIER HSPgR HSBiopsy siteMutation472-102051Lymph nodeY537C 1610 A>G only665-518218Lymph nodeY537S 1610 A>C Y537N 1609 T>A D538G 1613 A>G1555-201105SkinY537C 1610 A>G only1863-10162130Lymph nodeD538G 1613 A>G only3354-417015Lymph nodeY537S 1610 A>C Y537N 1609 T>A D538G 1613 A>G4268-516950SkinY537C 1610 A>G only4466-24270159Lymph nodeY537N 1609 T>A only4673-20224110Lymph nodeY537N 1609 T>A and D538G 1613 A>G4952-20275138SkinY537S 1610 A>C and Y537C 1610 A>G5040-101740Lymph nodeY537S 1610 A>C only5140-101895IBTRY537S 1610 A>C onlyAbbreviations: HER2, human epidermal growth factor receptor 2; LI, labeling index; ER, estrogen receptor; HS, histoscore; PgR, progesteron receptor; ET, endocrine therapy; IBTR, ipsilateral breast tumor recurrence; SD, stable disease; PD, progressive disease; MPA, medroxyprogesterone acetate

Two biopsies were performed in 8 women, in which four women had primary and recurrent/metastatic samples. Four out of these 8 women acquired ESR1 mutation, whereas no ESR1 mutation could be identified at first biopsy.

Conclusions: We demonstrated the sensitive detection and accurate quantification of low frequency ESR1 mutations in 270 primary breast cancer samples and 55 recurrent/metastatic samples using ddPCR assay. This technique could prove a useful method for the precise detection of ESR1 mutations in endocrine therapy resistant cases.

Citation Format: Takeshita T, Yamamoto Y, Yamamoto-Ibusuki M, Inao T, Sueta A, Fujiwara S, Iwase H. Clinical significance of ESR1 mutations using droplet digital polymerase chain reaction assay in 325 breast cancer samples. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P6-07-07.

Abstract P3-07-11: High activation of PI3K pathway defined by PIK3CA mutation, PTEN, and INPP4B expression are associated with trastuzumab efficacy in HER2-positive breast cancer

Background

Aberrations of phosphoinositide-3-kinase (PI3K) pathway are extensively found in many human cancers through several mechanisms, including mutation or amplification of PIK3CA and loss of phosphatase and tensin homolog (PTEN) and inositol polyphosphate 4-phosphatase-II(INPP4B). In breast cancer, a number of studies have suggested the putative mechanism of resistance to trastuzumab therapy in terms of PI3K pathway activation. We aimed to evaluate the predictive relevance of these biomarkers to trastuzumab efficacy in HER2-positive disease.

Patients and Methods

A total of 43 breast cancer patients with HER2-positive who received both neoadjuvant treatment and surgery at Kumamoto University Hospital between 2004 and 2012 were selected. The regimens of chemotherapy included anthracycline or taxane-containing drugs in combination with trastuzumab. Using pretreatment tumor tissues, PIK3CA mutations (E542K, E545K, and H1047R) were analyzed by direct dideoxynucleotide sequencing and digital PCR methods. Additionally, the expressions of PTEN, pAkt, and INPP4B were assessed by immunohistochemistry (IHC).

Results

The overall pathological complete response (pCR) rate was 60%. Direct sequencing detected PIK3CA mutations in 21% of all patients, whereas digital PCR detected them in 26 % when the cutoff point of the mutation was set at 1%. In some cases, it was difficult to differentiate mutant DNA from artifact by direct sequencing, but we could identify the mutation clearly using digital PCR. We found the correlation between the proportion of the PIK3CA mutation and the pCR rate; the pCR rates in the patients with PIK3CA mutations with cut-off of 1%, 10% and 20% were 55%, 29%, and 0%, respectively.

There were no significant correlations of clinicopathological features with PIK3CA mutations, copy number status, PTEN, and pAkt expression. Low INPP4B expression was associated with larger tumor size (P = 0.035), and higher nuclear grade (P = 0.031) compared to high expression.

We evaluated the contribution of biomarkers related to the PI3K pathway to the prediction of pCR by logistic regression models. In multivariate analysis, activation of the PI3K pathway due to either PIK3CA mutation or low PTEN expression were related to poorer response to trastuzumab (OR of predictive pCR was 0.11, P = 0.041). Similarly, high activation defined as PIK3CA mutation or low expression of PTEN or INPP4B tend to have lower pCR (OR was 0.14, P = 0.064).

Conclusions

1. Digital PCR has potential to complement the direct sequencing data, leading to more accurate measurement of the mutation frequency.

2. Our findings provide additional support for the recently published studies regarding activating mutation in PIK3CA in HER2-positive breast cancer, and further suggest that integrated biomarkers of PIK3CA mutation, PTEN, INPP4B are stronger predictors of trastuzumab response than either one alone.

Citation Format: Sueta A, Yamamoto Y, Takeshita T, Yamamoto-Ibusuki M, Iwase H. High activation of PI3K pathway defined by PIK3CA mutation, PTEN, and INPP4B expression are associated with trastuzumab efficacy in HER2-positive breast cancer. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P3-07-11.

Abstract P4-09-01: FGFR1 protein expression is associated with prognosis in primary breast cancer: A comprehensive analysis of gene copy number, mRNA and protein expression

Background: The Cancer Genome Atlas (TCGA) showed that copy number gain/amplification of FGFR1 was around 10% in primary breast cancer. FGFR1 gene amplification in breast cancer has been reported in some studies, more likely seen in ER-positive subtype. Several preclinical and clinical studies demonstrated that FGFR1 was one of novel targets of therapy for metastatic breast cancer. Previous studies suggested that aberrant FGFR1 expression was associated with poor prognosis, while there was no report that compared copy number aberration, mRNA and protein expression. The aim of this study is to analyze FGFR1 gene copy number, expression levels of FGFR1 mRNA and FGFR1 protein in ER-positive/HER2-negative primary breast cancer, and to examine the relationship between FGFR1 status and clinicopathological parameters including prognosis.

Methods: The cohort of this study included 307 ER-positive/HER2-negative primary invasive breast cancer patients treated with standard care at Kumamoto University Hospital between June 2000 and January 2011. We performed a comprehensive analysis of FGFR1 at the levels of gene copy number, mRNA and FGFR1 protein expression analyzed by qPCR, qRT-PCR and immunohistochemistry, respectively.

Results: FGFR1 gain/amplification was identified in 43 (14.0%) out of 307 patients. FGFR1 gain/amplification had significantly associated with higher nuclear grade (p=0.010). No correlations between FGFR1 mRNA expression levels and any clinicopathological factors were found. Expression levels of FGFR1 protein was positively associated with invasive tumor size (p=0.039). Modest positive correlations between these three (FGFR1 gene gain/amplification, expression levels of FGFR1 mRNA and FGFR1 protein) were found. The univariate analysis revealed that high FGFR1 protein expression was significantly related to poor prognosis (p=0.0019, HR: 2.63, 95%CI: 1.17-5.98) in terms of relapse-free survival (RFS) but not breast cancer-specific survival. The univariate analysis did not show that any factors except FGFR1 protein expression were significantly associated with RFS in this cohort.

Conclusion: Expression levels of FGFR1 protein may be an independent prognostic factor in terms of RFS for ER-positive/HER2-negative breast cancer patients receiving standard care.

Citation Format: Tomiguchi M, Yamamoto Y, Yamamoto-Ibusuki M, Yamaguchi R, Fujiki Y, Fujiwara S, Sueta A, Takeshita T, Inao T, Iwase H. FGFR1 protein expression is associated with prognosis in primary breast cancer: A comprehensive analysis of gene copy number, mRNA and protein expression. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P4-09-01.

Associations Between Elastography Findings and Clinicopathological Factors in Breast Cancer

This study aimed to explore the clinical significance of breast tumor tissue stiffness based on ultrasound elastographic evaluation in clinical breast cancer. Tumor tissue stiffness is mainly regulated by interactions among tumor cells, stromal cells, and extracellular matrix and was recently regarded as a representative feature of tumor microenvironment. Basic research has already revealed that the tumor stiffness can lead to tumor progression; however, little is known about its clinical significance because thus far, no useful modality is available in the clinical setting. We investigated the tumor stiffness by strain elastography in 503 consecutive patients with invasive breast cancer. Correlations between stiffness and clinicopathological factors, including tumor size, lymph node involvement, tumor subtypes, and stromal-related genes' expressions in primary breast tumor, were statistically examined. We identified that clinical tumor stiffness significantly correlated with lymph node involvement and invasive tumor size but not with hormonal receptor expressions, human epidermal growth factor receptor type 2 status, and ki67 labeling index by analyses of both categorical and continuous variables of stiffness. On multivariate analyses, axillary lymph node metastasis was an independent factor that influenced the stiffness of primary breast tumor. In the gene expression analyses, relatively hard tumors had a significantly high gene expression of lysyl oxidase compared with soft tumors. Our study showed a close relationship between primary tumor stiffness by elastographic evaluation and lymph node involvement in clinical breast cancer. Further investigations on tumor-related tissue stiffness are required.

Prognostic role of PIK3CA mutations of cell-free DNA in early-stage triple negative breast cancer

PIK3CA is an oncogene that encodes the p110α component of phosphatidylinositol 3‐kinase (PI3K); it is the second most frequently mutated gene following the TP53 gene. In the clinical setting, PIK3CA mutations may have favorable prognostic value for hormone receptor‐positive breast cancer patients and, during the past few years, PIK3CA mutations of cell‐free DNA (cfDNA) have attracted attention as a potential noninvasive biomarker of cancer. However, there are few reports on the clinical implications of PIK3CA mutations for TNBC patients. We investigated the PIK3CA major mutation status of cfDNA as a noninvasive biomarker of cancer using droplet digital polymerase chain reaction (ddPCR), which has high level sensitivity and specificity for cancer mutation, in early‐stage 49 triple negative breast cancer (TNBC) patients. A total of 12 (24.4%) of 49 patients had PIK3CA mutations of cfDNA. In a median follow up of 54.4 months, the presence of PIK3CA mutations of cfDNA had significant impacts on relapse‐free survival (RFS; P = 0.0072) and breast cancer‐specific survival (BCSS; P = 0.016), according to the log‐lank test. In a Cox proportional hazards model, the presence of PIK3CA mutations of cfDNA had significant prognostic value in the univariate and multivariate analysis. Additionally, the presence of PIK3CA mutations of cfDNA was significantly correlated with positive androgen receptor phosphorylated form depending on PI3K signaling pathway (pAR) which is independent favorable prognostic factors of TNBC. We demonstrated that the presence of PIK3CA major mutations of cfDNA could be a discriminatory predictor of RFS and BCSS in early‐stage TNBC patients and it was associated with PI3K pathway‐dependent AR phosphorylation.

We demonstrated the presence of PIK3CA major mutations of cfDNA could be discriminatory predictor of RFS and BCSS in early‐stage TNBC patients which may be associated with PI3K pathway dependent AR phosphorylation.

Abstract P3-04-15: Ethinylestradiol treatment downregulates ER and upregulates PgR; Immunohistochemical analysis in postmenopausal breast cancer tissues after prior long-term estrogen-deprivation therapy

Background: Estrogen receptor (ER) positive breast cancer can often be treated by hormone therapy; however a certain population of ER-positive patients becomes resistant to hormone therapy after long-term hormone treatment. Ethinylestradiol (EE2) is a derivative of estrogen which has shown promising effects on in these patients. Methods: We successfully obtained tissue samples from 6 patients undergoing EE2 treatment and examined 13 well-known breast cancer-related factors by analyzing their gene expression and by immunohistochemistry. Of the 6 patients, 5 responded but one patient did not.

Results: Before EE2 treatment, staining for both ER and androgen receptor (AR) was strong in the nucleus, with weak staining of the progesterone receptor (PgR). EE2 treatment significantly down-regulated ER and up-regulated PgR while nuclear and cytosolic AR were oppositely down- and up-regulated, respectively, by EE2. Cytosolic staining of BRCA1 was significantly up-regulated by EE2 whereas nuclear staining tended to decrease. Individual comparisons suggested less induction of PgR and decreasing AKT but increasing pAKT in the non-responder following EE2 treatment. Conclusion: Our observations revealed that EE2 activated ER downstream genes, although it did not stimulate cell growth. This suggests that hormone resistant cells might receive growth signals from a non-genomic pathway and this may be reflected in their sensitivity to EE2 treatment.

Citation Format: Hirotaka Iwase, Yoko Omoto, Takashi Takeshita, Mutsuko Yamamoto-Ibusuki, Mitsuhiro Hayashi, Aiko Sueta, Saori Fujiwara, Yutaka Yamamoto. Ethinylestradiol treatment downregulates ER and upregulates PgR; Immunohistochemical analysis in postmenopausal breast cancer tissues after prior long-term estrogen-deprivation therapy [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr P3-04-15.

Abstract P6-01-20: A role of MACC1 expression and its regulation of the HGF/c-Met pathway in breast cancer

Background

The newly identified gene, metastasis-associated in colon cancer 1 (MACC1), is suggested to be a transcriptional regulator of the receptor tyrosine kinase gene c-Met, leading to cancer progression and metastasis in colorectal cancer. Also in breast cancer, aberrant hepatocyte growth factor (HGF) / c-Met signaling has been shown to contribute to worse prognosis and confer resistance to endocrine therapy or trastuzumab treatment, however, little is known of the role of MACC1. Here, we report its impact on the survival for breast cancer patients and the biological function in the cell lines.

Methods

A total of 300 breast cancer patients who received both surgery and adjuvant treatment at Kumamoto University Hospital between 2001 and 2009 were selected. We analyzed expressions of MACC1 by reverse transcription polymerase chain reaction (RT-PCR) and immunohistochemistry (IHC) to evaluate the associations of its expression with breast cancer survival. In an in vitro study, the expressions of MACC1 were examined by Western blotting in breast and colorectal cancer cell lines. After transfection with a MACC1-harboing plasmid, we evaluated the activities of cMet protein and cell motility and proliferation. Further, the binding ability of MACC1 to the cMet promoter was evaluated using chromatin immunoprecipitation (ChIP) assay.

Results

In survival analyses, reduced MACC1 expressions were associated with patient mortality. Cox proportional hazards model showed that MACC1 mRNA (HR = 0.25, P = 0.001), MACC1 protein (HR = 0.37, P = 0.016), as well as axillary nodal status and estrogen receptor status, were independent predictors of mortality. No significant correlations between MACC1 expression and other clinicopathological factors were found. We found no strong positive correlation between MACC1 protein and c-Met mRNA expression with a Spearman’s coefficient of 0.16 (P = 0.0067). In the cell lines tested, MACC1 expression was much higher in colorectal cancer cells (DLD-1) than breast cancer cells (MCF7 and MDA-MB-231). To investigate the impact of MACC1 on the biological function of the cells, we transfected with MACC1 in breast cancer and colorectal cancer cells (SW480). MACC1 overexpression did not induce cMet expression in MCF7, whereas the corresponding cMet expression was upregulated in SW480 cells. Further, SW480 cells transfected with MACC1 showed enhanced migratory ability, whereas in MDA-MB-231 cells, transfection of MACC1 had no impact on this ability. In ChIP assay, the binding of MACC1 to the cMet promoter region was suggested in SW480 cells, but not in MCF7 cells.

Conclusions

Our findings provide some novel insights into the role of MACC1 for breast cancer, indicating that it plays different roles in breast cancer and in several other cancers. The biological mechanism of MACC1 which underlies improvement of breast cancer prognosis remains unelucidated. There is possibility that MACC1 does not act as the exclusive master regulator of the HGF/c-Met signaling involved in disease progression in breast cancer. Further studies to validate our results are needed.

Citation Format: Aiko Sueta, Yutaka Yamamoto, Mitsuhiro Hayashi, Takashi Takeshita, Mutsuko Ibusuki, Hirotaka Iwase. A role of MACC1 expression and its regulation of the HGF/c-Met pathway in breast cancer [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr P6-01-20.

The localization of HER4 intracellular domain and expression of its alternately-spliced isoforms have prognostic significance in ER+ HER2- breast cancer

Human epidermal growth factor receptors (HERs) are known to play a pivotal role in breast cancer, both as prognostic markers and as therapeutic targets. The importance of Her4 expression is, however, still controversially discussed; there are few reports on the clinical significance of HER4, its splice variants, and cleaved HER4 intracellular domains (4ICD) which function differently depending on their localization in breast cancer. In 238 primary invasive breast cancer patients, we analyzed the expression levels of HER4 extracellular (JM-a and JM-b) and intracellular (CYT-1 and CYT-2) domains as well as 4ICD localization, and tested the relationship with clinicopathological characteristics and prognosis. The predominantly-expressed extracellular domain was JM-a, and lower CYT-2 dominance was a factor related to better relapse-free survival. CYT-2-dominance with higher nuclear 4ICD expression was a favorable prognostic marker especially in patients with the ER+ HER2- subtype treated with endocrine therapy. The absence of cytoplasmic 4ICD staining was related to better prognosis in CYT-1-dominant patients. In conclusion, analysis of splicing variants and 4ICD localization should be considered when targeting HER4 as a novel ER+/HER2- breast cancer treatment.

Immunohistochemical analysis in ethinylestradiol-treated breast cancers after prior long-term estrogen-deprivation therapy

BACKGROUND

Estrogen receptor (ER) positive breast cancer can often be treated by hormone therapy; however a certain population of ER-positive patients become resistant to hormone therapy after long-term hormone treatment. Ethinylestradiol (EE2) is a derivative of estrogen, which has shown promising effects in these patients.

METHODS

We successfully obtained tissue samples from 6 patients undergoing EE2 treatment and examined 13 well-known breast cancer-related factors by immunohistochemistry. Of the 6 patients, 5 responded but one patient did not.

RESULTS

Before EE2 treatment, staining for both ER and androgen receptor (AR) was strong in the nucleus, and the progesterone receptor (PgR) was almost no staining. EE2 treatment significantly down-regulated ER and up-regulated PgR while nuclear and cytosolic AR were oppositely down- and up-regulated, respectively. Cytosolic staining of BRCA1 was significantly up-regulated by EE2 whereas nuclear staining tended to decrease. Individual comparisons suggested less induction of PgR and decreasing AKT but increasing pAKT in the non-responder following EE2 treatment.

CONCLUSIONS

Our observations revealed that EE2 activated ER downstream genes; however it did not stimulate cell growth. This suggests that hormone resistant cells might receive growth signals from a non-genomic pathway and this may be reflected in their sensitivity to EE2 treatment.

Differential role of MACC1 expression and its regulation of the HGF/c‑Met pathway between breast and colorectal cancer

The newly identified gene, metastasis‑associated in colon cancer 1 (MACC1), is suggested to be a transcriptional regulator of c‑Met, leading to cancer progression in colorectal cancer. To date however, little is known of the role of MACC1 in breast cancer. In a series of 300 breast cancer patients, we analyzed the association of MACC1 mRNA and protein expression with breast cancer survival using Cox proportional hazard models. In an in vitro study, we evaluated activities of c‑Met protein after transfection with a MACC1‑harboring plasmid as well as the binding ability of MACC1 to the c‑Met promoter using a chromatin immunoprecipitation (ChIP) assay. In survival analyses, reduced MACC1 expression was associated with patient mortality. MACC1 expression was an independent prognostic factor in multivariate analysis. In the cell lines tested, MACC1 expression was much higher in colorectal than in breast cancer cells. After cells were transfected with MACC1, c‑Met expression was not induced in MCF7 cells, whereas corresponding c‑Met expression was upregulated in SW480 cells. Further, SW480 cells transfected with MACC1 showed enhanced migratory ability, whereas in MDA‑MB‑231 cells, transfection of MACC1 had no impact on this ability. In ChIP assay, the binding of MACC1 to the c‑Met promoter was suggested in SW480 cells, but not in MCF7 cells. In conclusion, our findings provide some novel insights into the role of MACC1 in breast cancer, indicating that it plays different roles in breast and several other cancers. There is a possibility that MACC1 does not modulate the transcriptional role of c‑Met signaling in breast cancer.

An integrative analysis of PIK3CA mutation, PTEN, and INPP4B expression in terms of trastuzumab efficacy in HER2-positive breast cancer

The phosphoinositide-3-kinase (PI3K) pathway is commonly deregulated in breast cancer through several mechanisms, including PIK3CA mutation and loss of phosphatase and tensin homolog (PTEN) and inositol polyphosphate 4-phosphatase-II (INPP4B). We aimed to evaluate the predictive relevance of these biomarkers to trastuzumab efficacy in HER2-positive disease. We evaluated the effect of trastuzumab in 43 breast cancer patients with HER2-overexpression who received neoadjuvant treatment. PIK3CA mutation was examined by direct sequencing and digital PCR assay, and PIK3CA copy number was assessed by digital PCR assay of pretreatment tissues. PTEN, pAkt, and INPP4B were assessed by immunohistochemistry. Direct sequencing detected mutant DNA in 21% of all patients, but the incidence increased to 49% using digital PCR. The pathological complete response (pCR) rate in patients with PIK3CA mutations was 29% compared with 67% for those without PIK3CA mutations (P = 0.093), when the mutation was defined as positive if the mutant proportion was more than 10% of total genetic content by digital PCR. Low PTEN expression was associated with less pCR compared to high expression (33% versus 72%, P = 0.034). There were no significant associations of PIK3CA copy number, pAKt, or INPP4B with trastuzumab efficacy. In multivariate analysis, activation of the PI3K pathway due to either PIK3CA mutation or low PTEN were related to poorer response to trastuzumab (OR of predictive pCR was 0.11, 95%CI; 0.03–0.48). In conclusion, activating the PI3K pathway is associated with low pCR to trastuzumab-based treatment in HER2-positive breast cancer. Combined analysis of PIK3CA mutation and PTEN expression may serve as critical indicators to identify patients unlikely to respond to trastuzumab.

C6ORF97-ESR1 breast cancer susceptibility locus: influence on progression and survival in breast cancer patients

Genome-wide association studies have identified a single-nucleotide polymorphism (SNP) to be associated with an increased risk of breast cancer. The biology of one of the susceptibility locus C6ORF-ESR1 and whether it also contributes to progression of established disease has not yet been ascertained. We examined the association of rs2046210 and its six linkage disequilibrium SNPs with clinicopathological characteristics, prognosis, and gene expression levels of ESR1 and the C6ORFs (C6ORF97:CCDC170, C6ORF211, C6ORF96:RMND1) in 344 breast cancer tissue samples and 253 corresponding samples of adjacent normal tissue. Tumor genotypes with homozygous risk alleles were more frequent than normal tissues. The tumor genotypes of rs2046210 and rs6929137 with homozygous risk alleles showed worse relapse-free survival (RFS, P=0.038 and P=0.031, respectively), whereas no notable associations were observed with either clinicopathological characteristics or expression of the peripheral genes. Higher C6ORF97 expression correlated with ER negativity (P<0.0001), highly proliferative characteristics (P=0.0005 for Ki67, P<0.0001 for nuclear grade) and worse RFS in the ER+/HER2- cohort (P=0.013), whereas the other two C6ORFs showed the inverse associations. Furthermore, C6ORF97 showed significant worse prognostic values especially in luminal B subtype in the publically available data sets. rs2046210 and the upstream gene C6ORF97 might have substantial roles not only in carcinogenesis but also in progression toward a more aggressive phenotype in breast cancer patients, which suggests that functional studies of this locus are imperative.

Subsequent endocrine therapy after resistance to ethinylestradiol treatment for the late-stage metastatic breast cancer: A retrospective cohort study

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Background: Aromatase inhibitor (AI) is a most commonly used as the endocrine therapy in postmenopausal hormone-dependent breast cancer. Paradoxically, estrogen additive therapy using ethinylestradiol can be useful after long-term estrogen deprivation therapies with AI. Furthermore, there is a possibility of the beneficial effect of AI or fulvestrant as a subsequent endocrine therapy after EE2 failure. Methods: Ethinylestradiol (EE2; 3mg/day, TID) therapy was performed in 20 patients with metastatic breast cancer (median; 62 years-old, the mean observation time: 13.6 months.), who were heavily treated by sequential endocrine therapies (3rd or more line) including cytotoxic chemotherapies. We examined the efficacy of a subsequent endocrine therapy of AI or fulvestrant after becoming resistance to the EE2 therapy in the patients who got the disease control by the prior EE2 therapy. The primary endpoint was clinical benefit rate (CBR) and the secondary endpoint was time to treatment failure (TTF). (Registration number; UMIN 000002831, additional analysis). Results: Median TTF of EE2 treatment was 46 weeks (23-62+, 2 cases were ongoing). The response rate was 41% (9/22), the clinical benefit rate was 50% (11/22). The stable disease (< 6 months) was 18% (4/22) and another 3 cases were judged as progressive disease. Four cases withdrew due to nausea, fatigue and muscle-skeletal pain. In 20 cases progressed after disease control (SD or more) of EE2, a subsequent endocrine therapy, fulvestrant for 10 cases and AI for 10 cases, was performed. Fulvestrant group showed 50% (3 in 6) of CBR and 15 weeks (5-55+) of TTF, and AI-treated group showed 43% (3 in 7) of CBR and 19 weeks (5-33+) of TTF. Two in three cases, who became resistance to anti-estrogen treatment, got long SD by further EE2 re-therapy. Conclusions: Some cases showed clinical benefits of a subsequent therapy by AI or fulvestrant after becoming to EE2 failure. Taken together, sequential use of estrogen and anti-estrogen therapy (vice versa) could be one of the options as a salvage endocrine therapy for the patients with end-stage breast cancer.

Common genetic determinants of breast-cancer risk in East Asian women: a collaborative study of 23 637 breast cancer cases and 25 579 controls

In a consortium including 23 637 breast cancer patients and 25 579 controls of East Asian ancestry, we investigated 70 single-nucleotide polymorphisms (SNPs) in 67 independent breast cancer susceptibility loci recently identified by genome-wide association studies (GWASs) conducted primarily in European-ancestry populations. SNPs in 31 loci showed an association with breast cancer risk at P < 0.05 in a direction consistent with that reported previously. Twenty-one of them remained statistically significant after adjusting for multiple comparisons with the Bonferroni-corrected significance level of <0.0015. Eight of the 70 SNPs showed a significantly different association with breast cancer risk by estrogen receptor (ER) status at P < 0.05. With the exception of rs2046210 at 6q25.1, the seven other SNPs showed a stronger association with ER-positive than ER-negative cancer. This study replicated all five genetic risk variants initially identified in Asians and provided evidence for associations of breast cancer risk in the East Asian population with nearly half of the genetic risk variants initially reported in GWASs conducted in European descendants. Taken together, these common genetic risk variants explain ~10% of excess familial risk of breast cancer in Asian populations.

Abstract 3654: Associations of body mass index and its change with breast cancer risk by molecular subtypes: a case-control study in Japanese women

Introduction. Recently, the clinical relevance of molecular subtypes of breast cancer has been demonstrated, but the evidence on etiologic differences among them is limited. Some epidemiological studies in Western populations have shown that body-mass-index (BMI) is a risk factor for luminal-type breast cancer. However, it is unclear whether the impact of BMI on the risk differs among tumor subtypes in Japanese population. Methods. We conducted a case-control study with 715 case subjects and 1430 age- and menopausal status-matched controls to evaluate the associations of BMI at current age, age at 20 years, and its change (from age 20 years to the current age) with the breast cancer risk. We applied conditional logistic regression models to estimate odds ratios (ORs) and 95% confidence intervals (CIs). Tumor subtypes were determined by estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor 2(HER2) and divided into four subtypes: luminal, luminal / HER2, HER2-rich, and triple-negative subtype. Results. Current BMI and BMI change were positively associated with the risk of postmenopausal breast cancer. On stratified analyses by tumor subtype, we observed the associations between current BMI, BMI change and thepostmenopausal breast cancer risk for luminal subtype; OR for each 1 kg/m2increase of current BMI was 1.14 (95%CI: 1.07 - 1.20) and the corresponding OR of BMI change was 1.16 (1.09 - 1.23) (each Ptrend &lt; 0.001). Additionally, we found the same tendency for triple-negative subtype; the OR for 1 kg/m2 increase of current BMI was 1.21 (1.05 - 1.39), and that for BMI change was 1.18 (1.02 - 1.36) (Ptrend was 0.008 and 0.024, respectively). No significant associations among them were seen for the other subtypes. In premenopausal women, the suggestive inverse association was observed between BMI change and breast cancer risk only for luminal subtype; OR of BMI change was 0.93 (0.87 - 1.00, Ptrend= 0.054). There were no associations between BMI at age 20 years and the risk for any tumor subtypes. Conclusions. BMI and its change are associated with the risk of both luminal and triple-negative breast cancer among postmenopausal women, despite the molecular and clinical differences between these two subtypes. Our results provide additional evidence for an etiological heterogeneity of breast cancer among tumor subtypes.

Citation Format: Aiko Sueta, Hidemi Ito, Tania Islam, Satoyo Hosono, Miki Watanabe, Hiroji Iwata, Kazuo Tajima, Hideo Tanaka, Keitaro Matsuo, Hirotaka Iwase. Associations of body mass index and its change with breast cancer risk by molecular subtypes: a case-control study in Japanese women. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 3654. doi:10.1158/1538-7445.AM2013-3654

Functional variants at the 11q13 risk locus for breast cancer regulate cyclin D1 expression through long-range enhancers

Analysis of 4,405 variants in 89,050 European subjects from 41 case-control studies identified three independent association signals for estrogen-receptor-positive tumors at 11q13. The strongest signal maps to a transcriptional enhancer element in which the G allele of the best candidate causative variant rs554219 increases risk of breast cancer, reduces both binding of ELK4 transcription factor and luciferase activity in reporter assays, and may be associated with low cyclin D1 protein levels in tumors. Another candidate variant, rs78540526, lies in the same enhancer element. Risk association signal 2, rs75915166, creates a GATA3 binding site within a silencer element. Chromatin conformation studies demonstrate that these enhancer and silencer elements interact with each other and with their likely target gene, CCND1.

Large-scale genotyping identifies 41 new loci associated with breast cancer risk

Breast cancer is the most common cancer among women. Common variants at 27 loci have been identified as associated with susceptibility to breast cancer, and these account for ∼9% of the familial risk of the disease. We report here a meta-analysis of 9 genome-wide association studies, including 10,052 breast cancer cases and 12,575 controls of European ancestry, from which we selected 29,807 SNPs for further genotyping. These SNPs were genotyped in 45,290 cases and 41,880 controls of European ancestry from 41 studies in the Breast Cancer Association Consortium (BCAC). The SNPs were genotyped as part of a collaborative genotyping experiment involving four consortia (Collaborative Oncological Gene-environment Study, COGS) and used a custom Illumina iSelect genotyping array, iCOGS, comprising more than 200,000 SNPs. We identified SNPs at 41 new breast cancer susceptibility loci at genome-wide significance (P < 5 × 10(-8)). Further analyses suggest that more than 1,000 additional loci are involved in breast cancer susceptibility.

Differential impact of body mass index and its change on the risk of breast cancer by molecular subtype: A case-control study in Japanese women

Body mass index (BMI) is an independent risk factor for luminal-type breast cancer in Western populations. However, it is unclear whether the impact of BMI differs according to breast cancer subtype in Japanese populations. We conducted a case–control study with 715 cases and 1430 age- and menopausal status-matched controls to evaluate the associations of BMI and its change (from age 20 years to the current age) with breast cancer risk. We applied conditional logistic regression models to estimate odds ratios (ORs) and 95% confidence intervals (CIs). Tumor subtypes were divided into four subtypes, namely the luminal, luminal/HER2, HER2-rich, and triple-negative subtypes. Current BMI and BMI change were positively associated with postmenopausal breast cancer risk. On stratified analysis by tumor subtype, we observed associations between current BMI and BMI change and postmenopausal breast cancer risk for the luminal subtype, with OR for each 1 kg/m² increase in current BMI of 1.14 (95% CI: 1.07 - 1.20) and the corresponding OR of BMI change of 1.16 (1.09 - 1.23) (each P_trend < 0.001). Additionally, we found the same tendency for the triple-negative subtype, with the OR for a 1 kg/m² increase in current BMI of 1.21 (1.05 - 1.39) and that for BMI change of 1.18 (1.02 - 1.36) (P_trend was 0.008 and 0.024, respectively). In premenopausal women, a suggestive inverse association was observed between BMI change and breast cancer risk for the luminal subtype only, with OR of BMI change of 0.93 (0.87 - 1.00, P_trend = 0.054). No association was seen between BMI at age 20 years and risk of any tumor subtype. In conclusion, BMI and its change are associated with the risk of both luminal and triple-negative breast cancer among postmenopausal Japanese women. These findings suggest the etiological heterogeneity of breast cancer among tumor subtypes.

P4-09-25: Impact of Body Mass Index (BMI) for Clinical Outcomes in Japanese Breast Cancer Patients

Background: Obesity is risk factor of breast cancer incidence in postmenopausal women including Japanese population. Currently, many clinical trials data were shown that obesity may be one of prognostic factors after primary treatment in postmenopausal breast cancer patients. However, the proportion of obesity is large different between Asain and Western populations in all breast cancer patients. There is a little paper about relationship between body mass index (BMI) and prognosis after surgery in Asian breast cancer population.

Methods: We conducted retrospective analysis about BMI and outcome after primary treatment in Japanese breast cancer patients. We reviewed the clinical data (height, weight, BMI, ER status, HER status, and outcome) based on our medical reports in our single institution. This research object is 1,100 patients with primary breast cancer who operated between Jan 2003 and Jan 2006 in our institution. Median follow up was 59 months (1-97). All patients are categorized into four groups according to BMI. The range of BMI is less than 18.5 kg/m2, from 18.5 to 24.9 kg/m2, 25 to 29.9 kg/m2, more than 30 kg/m2 in underweight, normal, overweight and obesity groups, respectively. Patient's characteristics are well balanced excluding age and menopausal status. Nobody is obesity in young women (less than 35 years old). The correlation BMI with disease free survival (DFS) and overall survival (OS) were statistically analyzed by using the Cox hazard model.

Results: 785 (71.3%), 88 (8%), 192 (17.5%), 35 (3.2%) patients were categorized into normal, underweight, overweight obesisty groups, respectively. Breast cancer recurrences including local and distant metastases were occurred in 126 patients (11.5%).66 (6%) patients died due to breast cancer recurrence (54 patients) and other disease (8 patients). The multivariate hazard ratio (HR) in obesity groups was tend to be high compared with normal groups in disease free survival and overall survival. HR for OS was 4.30 (95%CI, 1.79−10.3) in obesity group. However, there are no statistical significant differences among four groups. Especially, HR for DFS and OS was 2.90 (95% CI 1.15−7.30 p=0.024) and 7.05(95%CI 2.38−20.8 P&lt;0.001) in obesity group compared with normal group in ER positive patients, respectively. However, there are no statistical significant difference for DFS and OS among four groups in ER negative patients.

Conclusions: The proportion of obesity is very lower in Japanese population (3.2%) than Western population (about 25–30%). However, obesity might be risk factor for DFS and OS in Japanese breast cancer patients with ER positive similar with Western countries. The different proportion of BMI may be influenced the different overall survival rate in lymph node negative breast cancer patients between Japan and Western countries. This study is a first report of the association between obesity and clinical outcomes in Japanese breast cancer patients. However, a number of patients were limited and this study is retrospective analyses including heterogeneous subtypes in single institution. A large scale cohort study should be conducted based on the clinical trial in Japanese population.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P4-09-25.

P1-09-04: A Genetic Predictor for Breast Cancer Risk in a Japanese Population

Objective Genome-wide association studies (GWASs) have identified genetic variants associated with breast cancer. Most GWASs to data were conducted in women with European background and the extent to which these variants contribute as predictors of breast cancer among Japanese population is unknown.

Methods We analyzed 24 genetic variants that have been identified in previous GWASs and conducted a case-control study with 697 cases and age- and menopausal status- matched 1394 controls in the framework of the Hospital-based Epidemiologic Study at Aichi Cancer Center (HERPACC). All subjects were asked to provide information on lifestyle factors and blood samples for genetic studies. We fit conditional regression models with genetic variants and conventional risk factors including age, age at menarche, menopausal status, current body-mass-index, age at first live birth, regular exercise, family history of breast cancer, and referral pattern to our hospital. In addition, we created a polygenetic risk score, using the single nucleotide polymorphisms (SNPs) with statistically significant association with the breast cancer risk to measure the cumulative effect of multiple genetic risk variants. Furthermore, we evaluated the prediction model that included conventional risk factors by comparing with and without the genetic risk score, using c statistic.

Results Eleven SNPs (FGFR2-rs2981579, rs2981578, rs1219648, rs2420946, rs2981582, TOX3/TNRC9-rs8051542, rs3803662, LOC643714-rs4784227, C6orf97-rs2046210, 8q24-rs13281615, SLC4A7-rs4973768) revealed significant associations with breast cancer risk (each P &lt; 0.05 in either per allele, dominant, or recessive model). A dose-dependent association was observed between the risk of breast cancer and the genetic risk score, which is an aggregate measure of the alleles in 7 selected variants; rs2981579, rs3803662, rs2046210, rs13281615, rs4973768, rs3817198 and rs10931936. Compared to women with scores of 3 or less, odds ratios (ORs) for women with scores of 4–5, 6–7, 8–9 and 10 or more were 1.33 (95% confidence interval, 1.00 - 1.80), 1.71 (1.26 - 2.30), 3.01 (1.97 - 4.58) and 8.69 (2.74 - 27.5), respectively (Ptrend &lt; 0.001). The ORs for premenopausal women with the corresponding risk scores were 1.71 (1.12 - 2.63), 1.79 (1.15 - 2.78), 3.70 (1.98 - 6.93), and 14.0 (3.30–59.5), respectively, and those for postmenopausal women with the corresponding risk scores were 1.09 (0.72 - 1.66), 1.71 (1.12 - 2.61), 2.60 (1.44 - 4.71), 3.75 (0.57 - 24.4), respectively, compared to those with scores of 3 or less (each Ptrend &lt; 0.001). The c statistic for a model including the genetic risk score in addition to the conventional risk factors was 0.633, whereas 0.602 without it (P &lt; 0.001). Population-attributable fraction of the risk score was 33.8%.

Conclusion we identified a genetic predictor of breast cancer in a Japanese population. A risk model including genetic risk score may be useful to distinguish women at high-risk of breast cancer from those at low-risk, particularly in the context of targeted prevention.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P1-09-04.