A progressive and refractory case of breast cancer with Cowden syndrome

BACKGROUND

Cowden syndrome is a rare autosomal-dominant disease with a high risk of malignant tumors of the breast, commonly caused by germline mutations in the PTEN gene. Most breast cancers related to Cowden syndrome showed typically a slow-growing and favorable clinical course. Here, we report a progressive case of triple-negative breast cancer in a patient who was diagnosed with Cowden syndrome.

CASE PRESENTATION

A 35-year-old female with breast cancer was referred to our hospital. Histopathological examination of the tumor showed that it was triple-negative breast cancer with high proliferation marker. Preoperative positron emission tomography-computed tomography showed abnormal uptake in the left cerebellar hemisphere in addition to the right breast and axillary lymph node. Brain T2-weighted magnetic resonance imaging revealed hyperintense bands in the left cerebellar hemisphere lesion, which demonstrated a "tiger-stripe" appearance. The patient's mother had died of endometrial cancer. Subsequently, she underwent genetic testing, leading to a diagnosis of Cowden syndrome with a pathogenic variant c.823_840del.18 at exon 8 in PTEN. She was treated with neoadjuvant chemotherapy of eribulin and cyclophosphamide followed by adriamycin and cyclophosphamide. However, her tumors increased after these treatments. She was immediately surgically treated and received adjuvant chemotherapy of capecitabine. Unfortunately, the cancer recurred in the lung nine months after surgery. We then administered paclitaxel and bevacizumab therapy, but the disease rapidly progressed. Consequently, the patient died due to breast cancer about three months after recurrence.

CONCLUSION

We report an aggressive case of cancer with Cowden syndrome which was resistant to standard chemotherapy. Alteration of the phosphatidylinositol-3 kinase/Akt/mammalian target of rapamycin pathway due to inactivating PTEN protein may be associated with chemoresistance and serves as a candidate for therapeutic intervention in PTEN-related cancers.

Cardiac computed tomography-derived myocardial tissue characterization after anthracycline treatment

AIMS

Understanding cardiac function after anthracycline administration is very important from the perspective of preventing the onset of heart failure. Although cardiac magnetic resonance and echocardiography are recognized as the 'gold standard' for detecting cardiotoxicity, they have many shortcomings. We aimed to investigate whether cardiac computed tomography (CCT) could replace these techniques, assessing serial changes in cardiac tissue characteristics as determined by CCT after anthracycline administration.

METHODS AND RESULTS

We prospectively investigated 15 consecutive breast cancer patients who were scheduled to receive anthracycline therapy. We performed echocardiography and CCT before and 3, 6, and 12 months after anthracycline treatment. The mean cumulative administered anthracycline dose was 269.9 ± 14.6 mg/m² (doxorubicin-converted dose). Of the 15 enrolled patients who received anthracycline treatment for breast cancer, none met the definition of cardiotoxicity. The CCT-derived extracellular volume fraction tended to continue to increase after anthracycline treatment and had relatively similar dynamics to the left ventricular ejection fraction and global longitudinal strain as determined by echocardiography.

CONCLUSIONS

Our findings indicated that CCT could provide adequate information about the characteristics of myocardial tissue after anthracycline administration. CCT may improve the understanding of cardiotoxicity by compensating for the weaknesses of echocardiography. This technique could be useful for understanding cardiac tissue characterization as a 'one-stop shop' evaluation, providing new insight into cardiooncology.

Predictive and prognostic significance of BRCAness in HER2-negative breast cancer

BACKGROUND

BRCAness is characterized as the phenotypes shared between some sporadic tumors and BRCA1/2 mutation cancers resulting in defective homologous recombination. The predictive or prognostic value of BRCAness in HER2-negative breast cancer patients who have received neoadjuvant chemotherapy (NAC) is not fully elucidated.

METHODS

We retrospectively selected 101 high-risk HER2-negative patients diagnosed with stage I-III breast cancer who underwent NAC treatment and evaluated BRCA1-like phenotype using multiplex ligation-dependent probe amplification assay. In an analysis of BRCAness, 95 out of 101 patients were analyzed.

RESULTS

In total, 70 (74%) patients had sporadic-type tumors and 25 (26%) had BRCA1-like tumors according to pre-treatment samples. The BRCA1-like phenotype was not associated with pathological complete response (pCR) rate in the entire cohort. In survival analysis, pre-treatment BRCA1-like phenotype was not associated with survival. On the other hand, post-treatment BRCA1-like patients apparently showed shorter relapse-free survival (log-rank P = 0.016) and breast cancer-specific survival (P < 0.001) compared with sporadic features. In multivariate analysis, only the post-treatment BRCA1-phenotype was significant prognostic factors (HR 5.67, 95% CI 1.19-29.3). Furthermore, we found phenotype change between BRCA1-like and sporadic type through NAC in 19% of non-pCR patients. Post-treatment Ki67 significantly decreased in the persistent sporadic tumors during treatment or sporadic tumors changed after NAC (P < 0.0001, P = 0.0078, respectively).

CONCLUSIONS

BRCAness may be useful biomarkers to predict prognosis for HER2-negative breast cancer refractory to standard chemotherapy. Our results pave the way for identifying patients who require alternative therapies.

Exosomal miRNA profiles of triple-negative breast cancer in neoadjuvant treatment

Triple-negative breast cancer (TNBC) is characterized by aggressive clinicopathological features and is associated with a poor prognosis. Identifying patients that are non-responsive to chemotherapy remains a critical goal for effective personalized therapies. In the present study, the predictive value of exosomal microRNAs (miRNAs) was investigated in patients with TNBC. Exosomes were isolated from patients with TNBC undergoing neoadjuvant chemotherapy. Microarray-based miRNA profiles were compared between patients with pathological complete response (pCR; n=12) and non-pCR (n=12). Furthermore, the miRNA profiles of non-pCR patients with breast cancer recurrence were compared with those with no recurrence. A total of 16 differentially expressed exosomal miRNAs were identified between the patients with pCR and non-pCR by microarray analysis. Of these, a combined signature of four miRNAs (miR-4448, miR-2392, miR-2467-3p and miR-4800-3p) could be used to discriminate between pCR and non-pCR patients with TNBC with an area under the curve value of 0.7652. Furthermore, this study found 43 differentially expressed miRNAs between the patients with non-pCR and recurrence and non-pCR patients without recurrence. In network analysis, 'pathway in cancer', 'focal adhesion' and 'cell cycle' were identified as the crucial pathways in patients with non-pCR who also developed recurrence. Several exosomal miRNAs may be useful biomarkers to predict treatment efficacy for TNBC. The present study identified patients who were resistant to standard chemotherapy and therefore more likely to develop breast cancer recurrence.

Cardiac computed tomography-derived extracellular volume fraction in late anthracycline-induced cardiotoxicity

Cardiotoxicity in the late phase after anthracycline drugs administration remains to be defined. Of the 44 patients who received anthracycline treatment, 7 were found to have cancer therapeutics–related cardiac dysfunction (CTRCD). The global longitudinal strain determined by echocardiography and myocardial extracellular volume fraction (ECV) determined by cardiac computed tomography (CCT) of the CTRCD(+) group were significantly higher than those of the control group and CTRCD(-) group, whereas there were no significant differences between the control and CTRCD(-) groups. Our findings indicated that CCT may be a tool comparable to echocardiography, indicating the effective evaluation of CTRCD by CCT.

Analysis of plasma HER2 copy number in cell-free DNA of breast cancer patients: a comparison with HER2 extracellular domain protein level in serum

BACKGROUND

HER2 (human epidermal growth factor receptor 2) status has been evaluated in breast cancer (BC) tissues by immunohistochemistry or in situ hybridization. We evaluated HER2 copy number (CN) assay in plasma cell-free DNA (cfDNA) from blood samples and compared it with protein measurements of HER2 extracellular domain (ECD) in serum.

METHODS

Serum HER2-ECD levels were measured by chemi-luminescence immunoassay using anti-HER2 monoclonal antibodies. Analyses were performed on 120 cases of primary BC, 30 cases of metastatic BC and 34 cases treated by neoadjuvant chemotherapy (NAC). This study was approved by Medical Research Review Advancement No. 1857 for Kumamoto University.

RESULTS

There was a positive correlation between HER2-CN ratios and HER2-ECD levels, in primary (n = 54) and metastatic (n = 30) HER2-positive BC (P = 0.003 and P < 0.001, respectively). HER2-ECD levels were significantly higher in patients with a larger number of metastatic sites (P = 0.02). The usefulness of HER2 levels in discriminating primary and metastatic HER2-positive BC evaluated by ROC curve analysis was better in the HER2-ECD assay than in the HER2-CN assay. In 34 patients who received NAC, there was a small decrease in HER2-CN ratios between before and after NAC (P = 0.10), while there was an obvious decrease in HER2-ECD levels between before and after NAC (P < 0.001).

CONCLUSION

Compared to HER2-ECD levels, the clinical usefulness of HER2-CN ratio was somewhat inferior. Improved measurement methods and further examination of the association with long-term prognosis and the response to anti-HER2 treatment analyzed by HER2-CN and HER2-ECD assay are required.

Abstract P5-11-12: Clinical value of ESR1 mutations from cell free DNA in ethynil estradiol treatment for metastatic breast cancer

Background: There are some cases in which estrogen addition therapy with ethinyl estradiol (EE2) is effective in cases in which aromatase inhibotor (AI) acquired resistance has been achieved after prolonged administration. In such case, ESR1 mutation was reported to be frequently seen. In this study, we examined the relation between histopathological factors, or ESR1 mutations detected by multiplex droplet digital PCR from cell free DNA (cfDNA) in patients’ and the effect of EE2 treatment.

Patients and methods: From 2011 to 2016, we conducted a prospective observational study of EE2 therapy (0.5 to 3 mg / day PO) in our department (registration No. UMIN000002831). ER/PgR expression by IHC in a part cases, and serum E2 and FSH levels and blood cell counts in all cases were evaluated before/after treatment. Droplet digital PCR (ddPCR) system by the QX200™ Droplet Digital™ PCR System (Bio-Rad laboratories, Hercules, CA, USA) which makes thousands of droplets and each of them contained one or no copy of the sequence of ESR1 gene reacted with a pair of primers and two TaqMan probes. The PCR data were quantified using QuantaSoft™ software (Bio-Rad laboratories) and data are expressed as a percentage of mutant to total (mutant plus wild type) for each sample.

Results: In this series, partial response (PR) was seen in 30% (12/40), long stable disease 12.5% (5/40), clinical benefit rate (CBR) 42.5% (17/40). The median EE2 dosing period in cases with CB was 8.4 months. AI was re-administered to 17 cases for which efficacy was obtained by EE2, and 8 cases had CB. After that, EE2 was re-challenge to 4 cases obtained effective cases. After EE2 treatment, serum E2 level increased and FSH decreased. In addition, the neutrophil-lymphocyte ratio increased, but its biological significance was unknown.

Point mutations (Y537S, Y537N, D538G) of the ESR1 gene in cell free DNA in plasma were searched in 21 cases before EE2 administration, and High frequent ESR1 mutations were seen in 10 cases (47%) in any mutative site. In the patients with wild type of ESR1 before treatment, there were tended to be more effective for EE2 treatment, but they were not statistically significant. Additionally, no relationship between PIK3CA mutations (E542x, E545x, H1047x, G1049x) and EE2 effect was seen.

Conclusion: The action mechanisms of EE2 treatment were reported as estrogen-induced apoptosis, which may not be related to ESR1 nor PIK3CA mutations. Further research related to EE2 treatment with biologic factors, such as gene alterations of the related factors, must be required.

Citation Format: Hirotaka Iwase, Takashi Takeshita, Mutsuko Ibusuki, Aiko Sueta, Mai Tomiguchi, Yoshitaka Fujiki, Yutaka Yamamoto. Clinical value of ESR1 mutations from cell free DNA in ethynil estradiol treatment for metastatic breast cancer [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P5-11-12.

Abstract P2-11-17: Expression levels of some genes associated with tumor shrinkage by neoadjuvant endocrine therapy were paradoxically related with poor prognosis in patients with ER-positive/HER2-negative operable breast cancer

Purpose: We previously published that the expression levels of 5 genes (ADCK2, CUL2, FAM13A, KRAS, LILRA2) related to tumor shrinkage by neoadjuvant endocrine therapy (NAET) were identified though the gene expression profiles (Goto-Yamaguchi L et al, Breast Cancer Res Treat. 72:353-362,2018). In this study, we examined whether expression levels of these 5 genes were associated with prognosis in patients with ER-positive/HER2-negative operable breast cancer.

Methods: Formalin-fixed paraffin embedded tumor tissues before systemic treatment were provided by 273 patients with ER-positive/HER2-negative operable breast cancer receiving standard of care at our institute from June 2000 to January 2011. We examined gene expression levels of these 5 genes determined by real time-quantitative PCR using RNA extracted from the tumor samples. We analyzed the prognostic impact of these 5 genes in terms of relapse-free survival (RFS) and breast cancer-specific survival (BCSS). We also study the relationship between 5 genes expression and clinic-pathological factors.

Results: Median follow-up time was 106 months. Among 5 genes, high expression levels of ADCK2 and CUL2 were significantly related with poor PFS (log-rank test, ADCK2: p=0.022, CUL2: p0.045) but not BCSS. On the other hand, high levels of FAM13A expression were significantly poor BCSS (log-rank test, p=0.042) but not RFS. Expression of KRAS and LILRA2 were not any correlation with prognosis. Multivariate analysis in terms of RFS revealed that ADCK2 was an independent prognostic factor (HR 2.26, 95%CI 1.04 to 5.07, p = 0.038). In addition, multivariate analysis in terms of BCSS revealed that FAM13A (HR 15.6, 95%CI 2.36 to 316.0, p = 0.0029), nodal status (HR 8.22, 95%CI 1.57 to 62.9, p=0.012) and PgR (HR 0.14, 95%CI 0.0068 to 0.93, p=0.042) were independent prognostic factors. Expression of ADCK2 and CUL2 were not associated with any clinic-pathological factors such as menopausal status, tumor size, nodal status, expression levels of ER and PgR, nuclear grade and ki67 labeling index. FAM13A expression was positively correlated with ki67 labeling index (chi-square test, p=0.0007).

Conclusion: Despite the genes associated with tumor shrinkage by NAET, ADCK2, CUL2 and FAM13A among the genes were positively correlated with poor prognosis. This paradoxical phenomenon showed that endpoint of short-term endocrine therapy such as tumor shrinkage may not be reflect that of long-term endocrine therapy such as PFS and BCSS.

Citation Format: Lisa Goto-Yamaguchi, Mutsuko Ibusuki-Yamamoto, Masako Takeno, Yositaka Fujiki, Mai Tomiguchi, Aiko Sueta, Yutaka Yamamoto. Expression levels of some genes associated with tumor shrinkage by neoadjuvant endocrine therapy were paradoxically related with poor prognosis in patients with ER-positive/HER2-negative operable breast cancer [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P2-11-17.

The role of exosomal microRNAs; focus on clinical applications in breast cancer

Despite several advances in targeted therapies for breast cancer, breast-cancer-associated death remains high in women. This is partially due to the lack of reliable markers predicting metastatic disease or recurrence after initial therapy. Recent research into the clinical validity of circulating cancer-specific biomarkers as a “liquid biopsy” is of growing interest. Of these, exosomal microRNAs (miRNAs) are promising candidate biomarkers for clinical use in breast cancer. In addition to their diagnostic value, exosomal miRNAs play an important role in predicting clinical outcome or treatment response. In this review, it is focused on the findings concerning exosomal miRNAs in relation to disease detection, prognostic impact and therapeutic effect in breast cancer, and discuss their clinical utility.

ESR1 and PIK3CA mutational status in serum and plasma from metastatic breast cancer patients: A comparative study

PURPOSE

Plasma and serum cell-free DNA (cfDNA) are useful sources of tumor DNA, but comparative investigations of the tumor mutational status between them are rare.

METHODS

we performed droplet digital PCR assay for representative hotspot mutations in metastatic breast cancer (MBC) (ESR1 and PIK3CA) in serum and plasma cfDNA concurrently extracted from the blood of 33 estrogen receptor-positive MBC patients.

RESULTS

ESR1 mutations in plasma cfDNA were found in 7 of the 33 patients; ESR1 mutations in serum cfDNA were detected in only one out of 7 patients with ESR1 mutations in plasma cfDNA. PIK3CA exon 9 and exon 20 mutations in plasma cfDNA were found in 3 and 7 out of the 33 patients, respectively; PIK3CA exon 9 mutations in serum cfDNA were detected in 2 out of 3 patients with PIK3CA exon 9 mutations in plasma cfDNA; PIK3CA exon 20 mutations in serum cfDNA were detected in 2 out of 7 patients with PIK3CA exon 20 mutations in plasma cfDNA.

CONCLUSIONS

Here we show the higher frequency of ESR1 and PIK3CA mutations in the plasma than in the serum in 33 MBC patients; therefore, serum samples should not be considered the preferred source of cfDNA.

APOBEC3B gene expression as a novel predictive factor for pathological complete response to neoadjuvant chemotherapy in breast cancer

Background

Apolipoprotein B mRNA editing enzyme catalytic polypeptide-like 3B (APOBEC3B) is a gene editing enzyme with cytidine deaminase activity and high expression of its mRNA in breast tumors have been shown to be associated with progressive cases and poor prognosis. In this study, we aimed to examine the relationship between the expression of APOBEC3B and the effect of neoadjuvant chemotherapy (NAC) using pretreatment biopsy tissue, and examined whether the expression of APOBEC3B influenced chemotherapy efficacy.

Methods

We retrospectively selected a total of 274 patients with primary breast cancer who received NAC in more than 4 courses and underwent surgery at our institute. We assessed the expression of APOBEC3B mRNA using pretreatment biopsy specimens of NAC by quantitative real-time PCR (qRT-PCR) and examined the relationship between APOBEC3B mRNA expression and sensitivity to chemotherapy using pathological complete response (pCR) as an indicator. Further, we assessed the prognostic value of APOBEC3B in the patients receiving NAC.

Results

APOBEC3B mRNA expression levels were successfully assessed in 173 (63.1%) of the 274 specimens. The total pCR rate was 36.4% (n = 63). An association between APOBEC3B expression levels and pCR was observed (Wilcoxon test, P ≤ 0.0001). The patients were divided into two groups, low (n = 66) and high (n = 107), according to the APOBEC3B expression levels, using the cut-off value calculated by the receiver operating characteristics (ROC) curve for pCR. The rate of pCR was significantly higher among the patients in the high group than among those in the low group (47.7% vs 18.2%, P ≤ 0.0001). High APOBEC3B expression was significantly associated with high nuclear grade (P = 0.0078), high Ki-67 labeling index (P = 0.0087), estrogen receptor (ER) negativity (P ≤ 0.0001) and human epidermal growth factor receptor 2 (HER2) negativity (P = 0.032). Tumor size (P = 0.011), ER (P ≤ 0.0001), HER2 (P = 0.0013) and APOBEC3B expression (P = 0.037) were independent predictive factors for pCR in multivariate analysis. However, there was no association between APOBEC3B expression and prognosis.

Conclusions

Our study showed that APOBEC3B mRNA expression correlated with sensitivity to NAC in breast cancer patients. In contrast to previous studies, APOBEC3B mRNA expression was not associated with breast cancer prognosis in patients receiving NAC.

Abstract 1583: Clinical significance of PIK3CA, AKT1, and ESR1 mutation in plasma cell-free DNA from estrogen receptor-positive breast cancer patients

Background: In endocrine therapy (ET) resistance mechanisms, PI3K / AKT pathway abnormality and ESR1 mutation are drawing attention. In recent large-scale clinical trials, it was revealed that identification of these genetic abnormalities in cell-free DNA (cfDNA) was useful for rapid assessment and monitoring of the therapeutic effect in ET-resistant breast cancer (BC). However, the frequency of them per treatment line and its clinical significance have not been verified. Here we studied the clinical significance of PIK3CA, AKT1, and ESR1 mutation according to the treatment line in estrogen receptor (ER)-positive BC.

METHODS: From 2003 to 2017, a total of 251 plasma specimens were collected from 128 patients with ER positive BC treated at our hospital. The breakdown were 133 plasma samples from 73 primary BC (PBC) patients and 118 plasma samples from 68 metastatic BC (MBC) patients. CfDNA was extracted from 500 μL of plasma. The hotspot of PIK3CA, AKT1, and ESR1 mutation in plasma cfDNA was verified using multiplex digital PCR method.

RESULTS: In the PBC patient group, PIK3CA mutation was recognized at 15.1%, AKT1 mutation at 1.4%, and ESR1 mutation at 2.7%. The presence or absence of PIK3CA mutation did not affect clinical outcome. In the MBC patient group, the frequency of PIK3CA mutation increased from 16% to 32% and that of ESR1 mutation increased from 23% to 41.9% as the treatment line advanced. Furthermore, we examined the time to treatment failure (TTF) by dividing into early treatment line and late treatment line. In the early treatment group, patients with PIK3CA mutation had significantly shorter TTF (P = 0.035). However, the presence or absence of ESR1 mutation did not affect TTF. On the other hand, in the late treatment group, patients with ESR1 mutation had significantly shorter TTF (P = 0.048). However, the presence or absence of PIK3CA mutation did not affect TTF. Since AKT1 mutation was rare in both PBC patients and MBC patients, its clinical significance was unknown.

CONCLUSION: We showed clinical significance of verification of PIK3CA, AKT1, and ESR1 mutation in cfDNA according to treatment line in ER positive BC patients.

Citation Format: Takashi Takeshita, Mai Tomiguchi, Aiko Sueta, Mutsuko Yamamoto-Ibusuki, Yutaka Yamamoto, Hirotaka Iwase. Clinical significance of PIK3CA, AKT1, and ESR1 mutation in plasma cell-free DNA from estrogen receptor-positive breast cancer patients [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 1583.

Clinical significance of plasma cell-free DNA mutations in PIK3CA, AKT1, and ESR1 gene according to treatment lines in ER-positive breast cancer

The somatic activation of PI3K/AKT pathway mutations, PIK3CA and AKT1, and ESR1 mutations in plasma cell-free DNA (cfDNA) has been studied as a non-invasive procedure to quickly assess and monitor disease progression or therapeutic effect in breast cancer (BC) patients, but the clinical significance of these mutations in late treatment lines (TLs) remains unclear. The subjects of this study were a total of 251 plasma samples from 128 estrogen receptor-positive (ER+) BC patients. Of these plasma samples, 133 were from 73 primary BC (PBC) patients, and 118 plasma samples were from 68 metastatic BC (MBC) patients. We developed droplet digital PCR (ddPCR) assays to verify the clinical significance of PIK3CA, AKT1, and ESR1 mutations in these patients. cfDNA PIK3CA mutations were observed in 15.1% of the PBC patients, while a cfDNA AKT1 mutation was observed in 1.4% of patients, and cfDNA ESR1 mutations were observed in 2.7% of patients. Patients with detectable cfDNA PIK3CA mutations were not associated with clinical outcomes. According to the TL, the prevalence of the PIK3CA and ESR1 mutations in cfDNA were lower in early TLs compared with late TLs. In the early TL group, patients with cfDNA PIK3CA mutations had a shorter time to treatment failure (TTF) than patients without mutations (P = 0.035). However, there was no statistically significant difference between patients with or without cfDNA ESR1 mutations. However, in the late TL group, patients with cfDNA ESR1 mutations had a shorter TTF than patients without mutations (P = 0.048). However, there was no statistically significant difference between patients with or without cfDNA PIK3CA mutations. Since the prevalence of cfDNA AKT1 mutation is low in both PBC and MBC patients, the impact of AKT1 mutations on the prognosis remains unclear. We have demonstrated the difference in the clinical significance of the hotspot PIK3CA, AKT1, and ESR1 mutations in cfDNA for each TL in ER+ BC patients.

Clinical significance of plasma cell-free DNA mutations in PIK3CA, AKT1, and ESR1 gene according to treatment lines in ER-positive breast cancer

The somatic activation of PI3K/AKT pathway mutations, PIK3CA and AKT1, and ESR1 mutations in plasma cell-free DNA (cfDNA) has been studied as a non-invasive procedure to quickly assess and monitor disease progression or therapeutic effect in breast cancer (BC) patients, but the clinical significance of these mutations in late treatment lines (TLs) remains unclear. The subjects of this study were a total of 251 plasma samples from 128 estrogen receptor-positive (ER+) BC patients. Of these plasma samples, 133 were from 73 primary BC (PBC) patients, and 118 plasma samples were from 68 metastatic BC (MBC) patients. We developed droplet digital PCR (ddPCR) assays to verify the clinical significance of PIK3CA, AKT1, and ESR1 mutations in these patients. cfDNA PIK3CA mutations were observed in 15.1% of the PBC patients, while a cfDNA AKT1 mutation was observed in 1.4% of patients, and cfDNA ESR1 mutations were observed in 2.7% of patients. Patients with detectable cfDNA PIK3CA mutations were not associated with clinical outcomes. According to the TL, the prevalence of the PIK3CA and ESR1 mutations in cfDNA were lower in early TLs compared with late TLs. In the early TL group, patients with cfDNA PIK3CA mutations had a shorter time to treatment failure (TTF) than patients without mutations (P = 0.035). However, there was no statistically significant difference between patients with or without cfDNA ESR1 mutations. However, in the late TL group, patients with cfDNA ESR1 mutations had a shorter TTF than patients without mutations (P = 0.048). However, there was no statistically significant difference between patients with or without cfDNA PIK3CA mutations. Since the prevalence of cfDNA AKT1 mutation is low in both PBC and MBC patients, the impact of AKT1 mutations on the prognosis remains unclear. We have demonstrated the difference in the clinical significance of the hotspot PIK3CA, AKT1, and ESR1 mutations in cfDNA for each TL in ER+ BC patients.

Clinical significance of monitoring ESR1 mutations in circulating cell-free DNA in estrogen receptor positive breast cancer patients

Background

The measurement of circulating cell-free DNA (cfDNA) may transform the management of breast cancer patients. We aimed to investigate the clinical significance of sequential measurements of ESR1 mutations in primary breast cancer (PBC) and metastatic breast cancer (MBC) patients.

Results

ESR1 mutations ratio in the PBC groups was used as the minimum cutoff for determining increases in cfDNA ESR1 mutation ratio. An increase in cfDNA ESR1 mutations was found in 13 samples of cfDNA from 12 (28.6%) out of 42 MBC patients. A total of 10 (83.3%) out of 12 MBC patients with increase cfDNA ESR1 mutations showed a poor response to treatment. In survival analysis, increase cfDNA ESR1 mutations may predict a shorter duration of post-endocrine-therapy effectiveness (P = 0.0033).

Methods

A total of 119 patients (253 plasma samples) with breast carcinoma were enrolled in this study. Cases were selected if archival plasma samples were available from PBC before and after treatment and from MBC gathered more than twice at the time of progression. cfDNA was isolated from the 77 PBC patients (154 plasma samples) and from the 42 MBC patients (99 plasma samples). To investigate any changes in each cfDNA ESR1 mutation before and after treatment, we analyzed the difference with cfDNA ESR1 mutations ratio in the first blood sample using droplet digital polymerase chain reaction (ddPCR).

Conclusions

We demonstrate that ddPCR monitoring of the recurrent ESR1 mutation in cfDNA of MBC patients is a feasible and useful method of providing relevant predictive information.

Prevalence of ESR1 E380Q mutation in tumor tissue and plasma from Japanese breast cancer patients

BACKGROUND

ESR1 mutations have attracted attention as a potentially important marker and treatment target in endocrine therapy-resistant breast cancer patients. The E380Q mutation, which is one of the ESR1 mutations, is associated with estradiol (E2) hypersensitivity, increased DNA binding to the estrogen response element, and E2-independent constitutive trans-activation activity, but its frequency in ESR1 mutations remains unknown. The present study aimed to investigate the E380Q mutation in comparison with the other representative ESR1 mutations.

METHODS

We screened a total of 62 patients (66 tumor tissues and 69 plasma cell-free DNA (cfDNA)) to detect ESR1 mutations (E380Q, Y537S, Y537N, Y537C, and D538G) using droplet-digital polymerase chain reaction. Plasma was collected at more than two points of the clinical course, in whom changes of ESR1 mutations under treatment were investigated.

RESULTS

We detected ESR1 mutations in 21% (12/57) of MBCs. The E380Q ESR1 mutation was found in 16% (2/12) and the other ESR1 LBD mutations were five (41.6%) of Y537S, and four each (33.3%) of D538G, Y537N, and Y537C, in 12 ESR1 mutant breast cancer patients. Five tumors had multiple ESR1 mutations: three had double ESR1 mutations; Y537S/E380Q, Y37S/Y537C, and Y537S/D538G, and two had triple ESR1 mutations; Y537S/Y537N/D538G. In plasma cfDNA analysis, the E380Q mutation was not detected, but increases in other ESR1 mutations were detected in 46.2% (6/13) of MBC patients under treatment.

CONCLUSIONS

We have shown that there are distinct populations of ESR1 mutations in metastatic tissue and plasma. Each ESR1 mutation may have different clinical significance, and it will be necessary to investigate them all.

Comparison of ESR1 Mutations in Tumor Tissue and Matched Plasma Samples from Metastatic Breast Cancer Patients

BACKGROUND: ESR1 mutation in circulating cell-free DNA (cfDNA) is emerging as a noninvasive biomarker of acquired resistance to endocrine therapy, but there is a paucity of data comparing the status of ESR1 gene in cfDNA with that in its corresponding tumor tissue. The objective of this study is to validate the degree of concordance of ESR1 mutations between plasma and tumor tissue. METHODS: ESR1 ligand-binding domain mutations Y537S, Y537N, Y537C, and D538G were analyzed using droplet digital PCR in 35 patients with metastatic breast cancer (MBC) (35 tumor tissue samples and 67 plasma samples). RESULTS: Of the 35 paired samples, 26 (74.3%) were concordant: one patient had detectable ESR1 mutations both plasma (ESR1 Y537S/Y537N) and tumor tissue (ESR1 Y537S/Y537C), and 25 had WT ESR1 alleles in both. Nine (25.7%) had discordance between the plasma and tissue results: five had mutations detected only in their tumor tissue (two Y537S, one Y537C, one D538G, and one Y537S/Y537N/D538G), and four had mutations detected only in their plasma (one Y537S, one Y537N, and two Y537S/Y537N/D538G). Furthermore, longitudinal plasma samples from 19 patients were used to assess changes in the presence of ESR1 mutations during treatment. Eleven patients had cfDNA ESR1 mutations over the course of treatment. A total of eight of 11 patients with MBC with cfDNA ESR1 mutations (72.7%) had the polyclonal mutations. CONCLUSION: We have shown the independent distribution of ESR1 mutations between plasma and tumor tissue in 35 patients with MBC.

Differential expression of exosomal miRNAs between breast cancer patients with and without recurrence

BACKGROUND

Exosomal microRNAs (miRNAs) are promising candidate biomarkers for diagnosis or prognosis for breast cancer. We investigated the prognostic role of exosomal miRNAs in serum samples derived from patients with breast cancer and compared miRNA expression between serum and tumor tissues.

METHODS

The miRNA profile derived from exosome between breast cancer patients with recurrence (n = 16) and without recurrence (n = 16) were compared by miRNA PCR array. Further, we examined the expression of miRNAs derived from tissues in the patients with breast cancer with (n = 35) and without recurrence (n = 39) by qRT-PCR.

RESULTS

Of 384 miRNAs, three miRNAs (miR-338-3p, miR-340-5p, and miR-124-3p) were significantly upregulated and eight (miR-29b-3p, miR-20b-5p, miR-17-5p, miR-130a-3p, miR-18a-5p, miR-195-5p, miR-486-5p, and miR-93-5p) were significantly downregulated in the patients with recurrence. We evaluated the expression of the miRNAs in tumor tissues. The patients with recurrence had higher levels of miR-340 at their primary site as well as in the serum. In contrast, miR-195-5p, miR-17-5p, miR-93-5p, and miR-130a-3p, derived from tumor tissues that were downregulated in the serum from patients with recurrence, were higher in the patients with recurrence than in those with no recurrence. In logistic regression analysis, miR-340-5p, miR-17-5p, miR-130a-3p, and miR-93-5p were significantly associated with recurrence.

CONCLUSIONS

Several exosomal miRNAs may be useful biomarkers to predict breast cancer recurrence. We show the different expression patterns of miRNAs between tumor tissues and serum. These findings may suggest selective mechanism of release of exosomal miRNAs by cancer cells to regulate their progression.

Analysis of ESR1 and PIK3CA mutations in plasma cell-free DNA from ER-positive breast cancer patients

Background

The measurement of ESR1 and PIK3CA mutations in plasma cell-free DNA (cfDNA) has been studied as a non-invasive method to quickly assess and monitor endocrine therapy (ET) resistant metastatic breast cancer (MBC) patients.

Methods

The subjects of this retrospective study were a total of 185 plasma samples from 86 estrogen receptor-positive BC patients, of which 151 plasma samples were from 69 MBC patients and 34 plasma samples were from 17 primary BC (PBC) patients. We developed multiplex droplet digital PCR assays to verify the clinical significance of ESR1 and PIK3CA mutations both in a snapshot and serially in these patients.

Results

cfDNA ESR1 and PIK3CA mutations were found in 28.9% and 24.6 % of MBC patients, respectively. The relation between ESR1 or PIK3CA mutations and clinical features showed that ESR1 mutations occurred mostly in patients previously treated by ET, which was not the case for PIK3CA mutations. The analysis of the clinical impact of those mutations on subsequent lines of treatment for the 69 MBC patients revealed that both ESR1 and PIK3CA mutations detection were related to a shorter duration of ET effectiveness in univariate analysis but only for ESR1 mutations in multivariate analysis. The monitoring of cfDNA in a subset of 52 patients showed that loss of ESR1 mutations was related to a longer duration of response, which was not the case for PIK3CA mutations.

Conclusions

We have demonstrated the clinical significance of on-treatment ESR1 mutations both in a snapshot and serially in comparison with PIK3CA mutations.

Clinical features of lenvatinib treatment in elderly patients with advanced thyroid cancer

Until recently, there had not been an effective systemic chemotherapy for advanced differentiated thyroid carcinoma (DTC); lenvatinib, a multi-tyrosine kinase inhibitor, has been proven effective for DTC, but has also been revealed to have adverse side effects including hypertension, hand-foot syndrome (HFS) and diarrhea. There have been few clinical studies focused on the characteristics, safety concerns or precautions for lenvatinib treatment in elderly patients. The present study administered lenvatinib to 18 patients with DTC in Kumamoto University Hospital (Kumamoto, Japan), with 9 patients in both the younger group (<75 years old) and elderly group (≥75 years old). The median maximum systolic blood pressure (sBP) was significantly different between the two groups (158 mmHg in the younger group vs. 173 mmHg in the elderly group; P=0.042). There were no significant differences in median maximum diastolic blood pressure (94 vs. 95 mmHg; P=1.00), median degree of sBP elevation (43 vs. 55 mmHg; P=0.199) or median days until hypertension diagnosis (2.11 vs. 2.33 days; P=0.436). There were also no significant differences in other toxicities (HFS, proteinuria or diarrhea). In conclusion, lenvatinib should be introduced carefully to elderly patients with DTC, as they tend to present with hypertension during treatment. However, there were no differences in other toxicities between the younger and elderly groups; lenvatinib was fully tolerated in patients with DTC >75 years old.

Lenvatinib, an oral multi-kinases inhibitor, -associated hypertension: Potential role of vascular endothelial dysfunction

BACKGROUND AND AIMS

Lenvatinib (Lenvima^®), an oral multi-kinase inhibitor, is effective in the treatment of differentiated thyroid carcinomas (DTCs). A severe adverse effect of lenvatinib is hypertension, thus limiting its use as an anti-cancer treatment. Although the pathogenesis of hypertension is generally assumed to involve microvascular bed reduction and an increase in peripheral vascular resistance due to a decrease in nitrogen oxide (NOx) production after vascular endothelial growth factor (VEGF) inhibition, the effects of hypertension on vascular endothelial function in actual patients remain unclear. Here, we examined how lenvatinib affects vascular endothelial function.

METHODS

Ten consecutive DTC patients who did not take any cardiovascular agents were orally administered 24 mg of lenvatinib once daily. Using an EndoPAT2000^® system, we used reactive hyperemia-peripheral arterial tonometry (RH-PAT) and evaluated vascular endothelial function on the basis of the RH-PAT index (RHI). We expressed the results as %RHI, which indicates the change compared with pretreatment levels. Additionally, we measured serum NOx and plasma VEGF concentrations pre- and post-treatment.

RESULTS

All of the patients treated with lenvatinib exhibited significant hypertension; the %RHI levels were significantly decreased the day after treatment with lenvatinib. Furthermore, serum NOx and plasma VEGF concentrations were significantly decreased and increased, respectively, compared with pretreatment levels. These results indicate that hypertension induced by lenvatinib may be caused by a decrease in nitric oxide production, as a result of VEGF inhibition and impaired vascular endothelial function.

CONCLUSIONS

We provide the first demonstration that lenvatinib causes hypertension via vascular endothelial dysfunction in human subjects.

Abstract P6-09-46: A comprehensive analysis of GNAS DNA copy number, levels of mRNA and protein expression in primary breast cancer

Background: Result of recent advances in genetics, guanine nucleotide binding protein, alpha stimulating (GNAS), transducer of signals from G-protein coupled receptors, has been noted that this factor is related with the onset and progression of tumor in various cancers. We aimed to analyze gene amplification, mRNA and protein expression of GNAS and their potential association with clinicopathological factors and prognosis in primary breast cancer.

Methods: The cohort of this study included 432 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 GNAS at the levels of gene copy number, mRNA and GNAS protein expression analyzed by qPCR, qRT-PCR and immunohistochemistry (IHC), respectively. In the IHC assessment of GNAS protein expression, an H-score&lt;150 was observed in 191 patients (44.2%), who were defined as having a low protein expression level, and an H-score≥150 was observed in 241 patients (55.8%) who were defined as having a high protein expression level.

Results: The median age at diagnosis was 60 (range 27-93). Three hundred fifteen (72.9%) of these were postmenopausal women. One hundred forty two patients (32.9%) had axillary lymph node metastasis. The median Ki67 labeling index was 23.6 (range 0.5-97.0). The subtypes were 321 ER+/HER2-, 24 ER+/HER2+, 34 ER-/HER2+ and 53 ER-/HER2-. Three hundred twenty one patients (75.9%) were treated with endocrine therapy and 146 patients (34.6%) chemotherapy. Most notably, a low levels of GNAS protein expression was observed in 191(44.2%) patients, and was positivity associated with Ki67 (P=0.028). Furthermore, univariate and multivariate analysis revealed that low GNAS protein expression was significantly related with poor relapse-free survival rate (Log-rank test; P=0.0013, OR:0.40, 05%CI:0.22-0.70) and breast cancer specific survival rate (Log-rank-test; P=0.041, OR:0.43, 95%CI:0.19-0.97). GNAS amplification and mRNA expression were not correlated with prognoses.

Conclusion: Contrary to expectations, GNAS expression was positively related with favorable tumor characteristics. Expression levels of GNAS protein may be an independent prognostic factor for primary breast cancer.

Citation Format: Tomiguchi M, Yamamoto Y, Yamamoto-Ibusuki M, Goto-Yamaguchi L, Fujiki Y, Sueta A, Takeshita T, Iwase H. A comprehensive analysis of GNAS DNA copy number, levels of mRNA and protein expression in primary breast cancer [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P6-09-46.

Abstract P1-02-09: Clinical significance of sequential measurements of ESR1 mutations in plasma cell-free DNA in estrogen receptor positive recurrent metastatic breast cancer patients

Background: The measurement of ESR1 mutations in plasma cell-free DNA (cfDNA) may transform the management of recurrent metastatic breast cancer (MBC) patients.

We aimed to investigate the clinical significance of sequential measurements of ESR1 mutations in MBC patients.

Methods: A total of 59 patients (113 plasma samples) with breast carcinoma were enrolled in this study. Cases were selected if archival plasma samples were available from PBC before and after treatment and from MBC gathered more than twice at the time of progression. cfDNA was isolated from the 17 PBC patients (34 plasma samples) and from the 42 MBC patients (99 plasma samples). To investigate any changes in each cfDNA ESR1 mutation before and after treatment, we analyzed the difference with cfDNA ESR1 mutations ratio in the first blood sample using droplet digital polymerase chain reaction (ddPCR).

Results:

The median changes in cfDNA ESR1 mutations ratio in the PBC group tended to be lower than that in the MBC group. The maximum change of each ESR1 mutation ratio in the PBC groups was used as the minimum cutoff for determining increases in cfDNA ESR1 mutation ratio. An increase in cfDNA ESR1 mutations was found in 13 plasma from 12 (28.6%) out of 42 MBC patients. 83.3% (10/12) of MBC patients with increase cfDNA ESR1 mutations showed a poor response to treatment. Interestingly, 12 MBC patients with increase cfDNA ESR1 mutations showed various response to endocrine therapy.

Patient characteristics of 12 MBC cases with increasing cell-free DNA ESR1 mutationsCaseAge at 1st blood drawSite of tissue biopsyIncreasing cfDNA ESR1 mutation  After increasing cfDNA ESR1 mutation analysis    2nd blood draw3rd blood draw4th blood drawETBOR to ET1866LungY537SNo riseNo riseLETPD2731LNY537S--LHRHa+ANAPD4458BreastD538GNo rise-FulPD5340OvaryY537S--No-5860BoneNo riseY537SNo riseNo-6267LNY537S--FulPD7261SkinY537N--EE2PR7561SkinNo riseY537NY537NFul /EXE+EVEPD/SD7748BoneNo riseY537S/D538G-No-8958BreastNo riseY537N-FulPD10168LungY537N--hdTORSD10856LNY537NNo rise-EE2PRAbbreviations: ER, estrogen receptor; PgR, progesteron receptor; HER2, human epidermal growth factor receptor 2; PBC, primary breast cancer; MBC, metastatic breast cancer receptor; cfDNA, cell-free DNA; ET, endocrine therapy; BOR, best overall response; LET, letrozole; PD, progressive disease; LN, lymph node; LHRHa, luteinizing hormone releasing hormone agonist; ANA, anastrozole; Ful, fulvestrant; EE2, ethinylestradiol; PR, partial response; EXE+EVE; exemestane+everolimus; SD, stable disease; hdTOR, high dose toremifene..

In survival analysis, increase cfDNA ESR1 mutations may predict a shorter duration of post-endocrine-therapy effectiveness (P = 0.0033).

Conclusions: We show that sequential measurements of the recurrent ESR1 mutation in plasma cfDNA of MBC patients is a feasible and useful method of providing relevant predictive information.

Citation Format: Takeshita T, Yamamoto Y, Yamamoto-Ibusuki M, Sueta A, Tomiguchi M, Iwase H. Clinical significance of sequential measurements of ESR1 mutations in plasma cell-free DNA in estrogen receptor positive recurrent metastatic breast cancer patients [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P1-02-09.

Abstract P1-02-13: Differential expression of exosomal miRNAs between breast cancer patients with recurrence and no-recurrence

Background

In recent years, there has been a concerted effort to identify biomarkers derived from body fluid in various cancers. Exosomal microRNA (miRNA) has been used as one of useful diagnostic or prognostic biomarkers. We aimed to investigate the prognostic role of the exosomal miRNAs in serum samples derived from patients with primary breast cancer. Additionally, we evaluated whether the exosomal miRNA in serum reflect the origin of primary tumor by means of comparing their expression levels between in serum and tumors.

Patients and Methods

Exosomes in serum sample (500uL) were extracted using ExoQuick (System Biosciences) and miRNAs were isolated using SeraMirTM Exosome RNA Amplification Kit (SBI). We compared the miRNA profile derived from exosome between the patients with breast cancer with recurrence (n=16) and without recurrence (n=16) by miRNA PCR array. Further, we examined the expression of miRNA derived from tumor tissues in the patients with breast cancer recurrence (n=35) and without recurrence (n=39) by qRT-PCR. All samples were collected before treatment and surgery.

Results

Of the 384 miRNAs, 11 miRNAs were significantly expressed; three miRNAs (miR-338-3p, miR-340-5p, and miR-124-3p) were significantly up-regulated and eight (miR-29b-3p, miR-20b-5p, miR-17-5p, miR-130a-3p, miR-18a-5p, miR-195-5p, miR-486-5p, and miR-93a-5p) were significantly down-regulated in the patients with recurrence compared to those without recurrence. Next, we evaluated expression of the above miRNAs in tumor tissues. The patients with recurrence have higher levels of miR-340 at their primary site as well as in the serum. On the contrary, miR-195-5p, miR-17-5p, miR-93-5p, and miR-130a-3p derived from tumor tissues that were down-regulated in the patients with recurrence in serum, were highly expressed in the patients with recurrence than those with no-recurrence. In logistic regression analysis, tumor size, miR-340-5p, miR-17-5p, miR-130a-3p, and miR-93-5p were significantly associated with breast cancer recurrence (each P &lt; 0.05).

Conclusions

Several exosomal miRNAs at diagnosis may be useful biomarker to predict the breast cancer recurrence. Moreover, we showed the different expression pattern of miRNAs between tumor tissues and serum. These findings may suggest selective mechanism of release of exosomal miRNA by cancer cells to regulate their progression. Further studies to confirm our results are needed.

Citation Format: Sueta A, Yamamoto Y, Tomiguchi M, Takeshita T, Ibusuki M, Iwase H. Differential expression of exosomal miRNAs between breast cancer patients with recurrence and no-recurrence [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P1-02-13.

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&gt;G only665-518218Lymph nodeY537S 1610 A&gt;C Y537N 1609 T&gt;A D538G 1613 A&gt;G1555-201105SkinY537C 1610 A&gt;G only1863-10162130Lymph nodeD538G 1613 A&gt;G only3354-417015Lymph nodeY537S 1610 A&gt;C Y537N 1609 T&gt;A D538G 1613 A&gt;G4268-516950SkinY537C 1610 A&gt;G only4466-24270159Lymph nodeY537N 1609 T&gt;A only4673-20224110Lymph nodeY537N 1609 T&gt;A and D538G 1613 A&gt;G4952-20275138SkinY537S 1610 A&gt;C and Y537C 1610 A&gt;G5040-101740Lymph nodeY537S 1610 A&gt;C only5140-101895IBTRY537S 1610 A&gt;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.