Clinical significance of progesterone receptor and HER2 status in estrogen receptor-positive, operable breast cancer with adjuvant tamoxifen

The role of adjuvant endocrine treatment in ER+, PR-, HER2- early breast cancer: a retrospective study of real-world data

PURPOSE

Estrogen receptor-positive (ER+), progesterone receptor-negative (PR-) and human epidermal growth factor receptor 2-negative (HER2-) breast cancer (BC) often developed resistance to endocrine treatment (ET). We aimed to explore (1) the different clinicopathological features between ER+/PR+/HER2- and ER+/PR-/HER2- BC, and (2) whether ER+/PR-/HER2- early BC patients could benefit from adjuvant ET.

METHODS

All patients treated for ER+/HER2- early BC who underwent surgery between 2010 and 2021 from a BC database in China were retrospectively examined. The cases followed up for less than six months were excluded.

RESULTS

The records of ER+/PR+/HER2- (n = 10843) and ER+/PR-/HER2- BC (n = 1193) cases were reviewed, with median follow-up times of 35.8 and 47.0 months, respectively. Compared with ER+/PR+/HER2- cases, ER+/PR-/HER2- BC occurred more in postmenopausal women (73.1% vs. 52.9%, p = 0.000) and were more likely to be T > 2 cm (40.6% vs. 37.6%, p = 0.048) and Ki67 > 20%+ (48.1% vs. 36.9%, p = 0.000). However, ER+/PR-/HER2- cases had fewer nodal involvement (32.9% vs. 36.9%, p = 0.000). Approximately 82.2% (981/1193) of ER+/PR-/HER2- patients received ET, while approximately 17.8% (212/1193) did not. Compared to patients did not receive adjuvant ET, the ET group had similar disease-free survival (DFS) (HR = 1.33, 95% confidence interval (CI): 0.68-2.59, p = 0.444) and overall survival (OS) (HR = 1.17, 95%CI: 0.37-3.68, p = 0.799). 65.7% of recurrent ER+/PR-/HER2- patients experienced distant relapse (65.7% vs. 48.2% (for ER+/PR + cases), p = 0.011). By comparison, recurrent ER+/PR+/HER2- patients were more likely to experience only local relapse (31.6% vs. 14.9% (for ER+/PR- cases), p = 0.007).

CONCLUSIONS

ER+/PR-/HER2- BC was a special subtype with aggressive clinicopathological features and more tend to have distant metastasis rather than nodal involvement or local relapse. ER+/PR-/HER2- early BC did not seem to benefit from adjuvant ET.

Risk of recurrence among patients with HR-positive, HER2-negative, early breast cancer receiving adjuvant endocrine therapy: A systematic review and meta-analysis

BACKGROUND

A systematic review and meta-analysis was conducted to assess breast cancer (BC) outcomes among patients with early-stage hormone receptor positive (HR+), human epidermal growth factor receptor 2-negative (HER2-) BC, receiving adjuvant endocrine therapy.

METHODS

Randomized controlled trials (RCTs) and real-world evidence (RWE) studies were identified using Ovid MEDLINE®, Embase, and Evidence-Based Medicine Reviews. Clinical and methodological similarities including alignment of outcome definitions with standardized definitions for efficacy endpoints criteria were assessed to evaluate feasibility of conducting a meta-analysis. Where feasible, 5-year probabilities of BC recurrence or death were estimated using a Bayesian hierarchical arm-based model.

RESULTS

Of 21 included studies, 8 RCTs and 4 RWE studies reported outcome data of interest. There was heterogeneity in outcome reporting, as well as variation in recurrence risk amongst studies with aligned reporting. Of the 12 studies, 10 were considered for inclusion in a meta-analysis of BC recurrence or death. Only a subgroup analysis of node-positive patients (3 studies; n = 7307) was deemed feasible. The 5-year probability of BC recurrence or death was 17.2% (95% credible interval: 14.6%-20.3%).

CONCLUSION

Although studies reporting recurrence outcomes were limited, there remains a high risk of BC recurrence, especially among node-positive patients. Approximately 1 in 6 women with node-positive HR+/HER2- early-stage BC receiving endocrine therapy experience recurrence or death within 5-years of initiating treatment, suggesting a need for novel treatments for this population.

Factors That Predict Biological Aggressiveness in Estrogen Receptor-Positive / Human Epidermal Growth Factor Receptor 2-Negative / Lymph Node-Negative Breast Cancer

Background: Traditionally, breast cancer is staged using TNM criteria: tumor size (T), nodal status (N), and metastasis (M). The Oncotype DX assay provides a recurrence score (RS) based on genomics that predicts the likelihood of distant recurrence in estrogen receptor–positive (ER+)/human epidermal growth factor receptor 2–negative (HER2–)/lymph node–negative (LN–) tumors.

Methods: We retrospectively reviewed the medical records of patients with ER+/HER2–/LN– breast cancer tumors who were evaluated between 2007 and 2017 with Oncotype DX RS. We compared the RS to tumor size, patient age, progesterone receptor (PR) status, and LN immunohistochemistry to assess for factors that may independently predict recurrence risk. We also compared tumor size to tumor grade.

Results: The data set included 296 tumors: 248 ER+/PR-positive (PR+)/HER2– and 48 ER+/PR-negative (PR–)/HER2–. RS ranged from 0 to 66, patient age ranged from 33 to 77 years, and tumor size ranged from 1 to 65 mm. No significant correlation was found between age and RS (r=–0.073, P=0.208). PR– tumors had a significantly higher RS regardless of size (PR– mean RS 30.8 ± 12.7; PR+ mean RS 16.3 ± 7.3; t(53)=7.6, P<0.0001). No significant correlation was seen between tumor size and RS for all tumors (r=–0.028, P=0.635), and this finding remained true for the PR+ tumor subgroup (r=0.114, P=0.072). However, a significant negative correlation was seen between tumor size and RS in the PR– subgroup (r=–0.343, P=0.017). Further analysis to ensure that differences in tumor grade did not account for this correlation showed equal distribution of well differentiated, moderately differentiated, and poorly differentiated tumors with no significant correlation between tumor size and grade.

Conclusion: Increasing tumor size may not be associated with increasing biological aggressiveness. Traditionally, smaller tumors are thought to be lower risk and larger tumors higher risk, with a tendency to use chemotherapy with large tumors. However, our data showed a negative correlation between tumor size and RS in the PR– subgroup. A tumor with PR negativity that reaches a large size without metastasizing may suggest a favorable tumor biology. These tumors may not receive as much benefit from chemotherapy as previously thought. Also, the higher RS seen in smaller PR– tumors may demonstrate PR– status as a predictor for higher risk of distant recurrence. We propose that all tumors meeting the ER+/PR–/LN– criteria, regardless of size, should be considered for genotyping, with the RS used to guide chemotherapy benefit.

Predictability of 21-Gene Recurrence Score Assay by Using Pathological and Immunohistochemical Parameters in Breast Cancer

Background:

Oncotype Dx is used to predict the long-term recurrence risk in patients with estrogen receptor (ER)-positive and human epidermal growth factor receptor 2 (HER2)-negative invasive breast cancer (BC). This study aimed at establishing a correlation between clinicopathological parameters and recurrence score (RS), subsequently improving predictability and ultimately justifying the use of the multigene assay.

Materials and methods:

A retrospective analysis of the pathology and clinical data of 114 female patients with BC who had Oncotype Dx testing between 2012 and 2019. The pathological parameters included are tumor cell type, tumor grade, pathological stage, and mitotic index (MI). The expression of ER, progesterone receptor (PR), HER2, and Ki67 was assessed by immunohistochemistry. A univariate and multivariate linear regression analysis was performed to assess the correlation between these parameters and the RS.

Results:

In univariate analysis, age (˂40 years), higher tumor grade, and low PR expression were significantly associated with higher RS (P = .02; ˂.001; and ˂.001, respectively). Both MI and Ki67 were also strongly correlated with an increase in the RS with a P value of .01 (Spearman correlation 0.34 and 0.33). In multivariate linear regression analysis, age, MI, and Ki67 lost their significance, but both higher grade and PR remained significantly associated with a higher RS along with the tumor stage (P ˂ .001; ˂.001; and .04, respectively).

Conclusions:

Tumor grade and PR immunohistochemical expression are the main predictors of RS in our study population. Other clinicopathological features were not significant predictors of change in RS in multivariate analysis.

Predictive and Prognostic Value of Selected MicroRNAs in Luminal Breast Cancer

Breast cancer (BrC) is the most frequent malignancy and the leading cause of cancer death among women worldwide. Approximately 70% of BrC are classified as luminal-like subtype, expressing the estrogen receptor. One of the most common and effective adjuvant therapies for this BrC subtype is endocrine therapy. However, its effectiveness is limited, with relapse occurring in up to 40% of patients. Because microRNAs have been associated with several mechanisms underlying endocrine resistance and sensitivity, they may serve as predictive and/or prognostic biomarkers in this setting. Hence, the main goal of this study was to investigate whether miRNAs deregulated in endocrine-resistant BrC may be clinically relevant as prognostic and predictive biomarkers in patients treated with adjuvant endocrine therapy. A global expression assay allowed for the identification of microRNAs differentially expressed between luminal BrC patients with or without recurrence after endocrine adjuvant therapy. Then, six microRNAs were chosen for validation using quantitative reverse transcription polymerase chain reaction in a larger set of tissue samples. Thus, miR-30c-5p, miR-30b-5p, miR-182-5p, and miR-200b-3p were found to be independent predictors of clinical benefit from endocrine therapy. Moreover, miR-182-5p and miR-200b-3p displayed independent prognostic value for disease recurrence in luminal BrC patients after endocrine therapy. Our results indicate that selected miRNAs’ panels may constitute clinically useful ancillary tools for management of luminal BrC patients. Nevertheless, additional validation, ideally in a multicentric setting, is required to confirm our findings.

Breast cancer global tumor biomarkers: a quality assurance study of intratumoral heterogeneity

Biomarker analysis of invasive breast carcinoma is useful for prognosis, as surrogate for molecular subtypes of breast cancer, and prediction of response to adjuvant and neoadjuvant systemic therapies. Breast cancer intratumoral heterogeneity is incompletely studied. Comprehensive biomarker analysis of estrogen receptor (ER), progesterone receptor (PR), HER2, and Ki67 labeling index was performed on each tissue block of 100 entirely submitted breast tumors in 99 patients. Invasive carcinoma and in situ carcinoma was scored using semiquantitative histologic score (H-score) for ER and PR, HER2 expression from 0 to 3+, and percentage positive cells for Ki67. Core biopsy results were compared with surgical excision results, invasive carcinoma was compared with in situ carcinoma, and interblock tumoral heterogeneity was assessed using measures of dispersion (coefficient of variation and quartile coefficient of dispersion). Overall concordance between core biopsy and surgical excision was 99% for ER and 95% for PR. Mean histologic score of ER was significantly lower in invasive carcinoma between core biopsy and surgical excision (p = 0.000796). Intratumoral heterogeneity was higher for PR than for ER (mean coefficient of variation for ER 0.08 stdv 0.13 vs. PR 0.26 stdv 0.41). Ki67 labeling index was significantly higher in invasive carcinoma as compared with associated ductal carcinoma in situ on surgical resection specimen (p ≤ 0.0001). Ki67 hotspots were identified in 47% of cases. Of 52 HER2 negative cases on core biopsy, 10 were scored as equivocal on surgical resection. None (0/10) were amplified by Her-2/neu fluorescence in situ hybridization. Overall, biomarkers on core biopsy showed concordance with the surgical excision specimen in the vast majority of cases. Biomarker expression of in situ closely approximates associated invasive carcinoma. Intratumoral heterogeneity of PR is greater than ER. Biomarker expression on diagnostic core biopsy or single tumor block is representative of breast carcinoma as a whole in most cases and is appropriate for clinical decision-making.

The Role of PET/MR Imaging in Precision Medicine

Fluorodeoxyglucose PET and PET/computed tomography have gained acceptance in the evaluation of disease. Nontargeted tracers have been used in the diagnosis of certain malignancies but may not be sensitive or specific enough to become standard of care. Newer targeted PET tracers have been developed that target disease-specific biomarkers, and allow accurate and sensitive detection of disease. Combined with the capabilities of MR imaging to evaluate soft tissue, precision imaging with PET/MR imaging can change the diagnosis. This article discusses specific areas in which precision imaging with nontargeted and targeted diagnostic agents can change the diagnosis and treatment.

Correlation of Oncotype DX Recurrence Score with Histomorphology and Immunohistochemistry in over 500 Patients

Oncotype Dx is used to determine the recurrence risk (RR) in patients with estrogen receptor positive (ER+) and lymph node negative (LN−) breast cancer. The RR is divided into low (0–17), intermediate (18–30), and high (31) to predict chemotherapy benefit. Our goal was to determine the association between histomorphology, immunohistochemistry, and RR. We retrospectively identified 536 patients with ER+ and LN− breast cancers that underwent Oncotype testing from 2006 to 2013. Tumor size ranged from 0.2 cm to 6.5 cm (mean = 1.3 cm) and was uniform in all 3 categories. The carcinomas were as follows: ductal = 63.2%, lobular = 11.1%, and mixed = 35.7%. The RR correlated with the Nottingham grade. Increasing RR was inversely related to PR positivity but directly to Her2 positivity. Of the morphologic parameters, a tubular(lobular) morphology correlated only with low-intermediate scores and anaplastic type with intermediate-high scores. Other morphologies like micropapillary and mucinous were uniformly distributed in each category. Carcinomas with comedo intraductal carcinoma were more likely associated with high RR. Forty-four patients with either isolated tumor cells or micrometastases were evenly distributed amongst the 3 RR. While there was only 1 ER discrepancy between our immunohistochemistry (3+ 80%) and Oncotype, up to 8% of PR+ cases (mean = 15%, median = 5%) and 2% of HER2+ cases were undervalued by Oncotype.

Estrogen receptor-beta genetic variations and overall survival in patients with locally advanced gastric cancer

Estrogen has been shown not only to reduce the incidence of colorectal cancer but also gastric cancer (GC). Polymorphisms in estrogen receptor β gene, ESR2, correlate with colorectal cancer survival. To better understand the role of ESR2 in GC, genomic DNA extracted from 169 Japanese patients and 172 patients from Los Angeles County (LAC) was analyzed for association of overall survival (OS) with three ESR2 polymorphisms, which are of biological significance using multivariable Cox proportional hazard regression. ESR2 rs1271572 (C>A) and rs3020443 (T>G) had univariate and multivariable associations with OS in the Japanese cohort, whereas the C allele of ESR2 rs2978381 (T>C) predicted favorable OS in the Japanese cohort but worse OS in the LAC cohort. The interaction term of the ESR2 rs2978381 and cohort group reached statistical significance. Our study provides evidence that genetic variations in ESR2 gene are significantly associated with survival in patients with locally advanced GC.

Potential of overcoming resistance to HER2-targeted therapies through the PI3K/Akt/mTOR pathway

Human epidermal growth factor receptor 2 (HER2) overexpression occurs in up to 30% of breast cancers and is a marker of aggressive disease. While HER2-targeted therapies have improved outcomes in these tumors, resistance to these agents develops in a large proportion of patients. Determining molecular mechanisms underlying resistance might help improve outcomes for patients with HER2-positive disease by allowing development of strategies to overcome resistance. Activation of signaling pathways involving the phosphoinositide 3-kinase/protein kinase B/mammalian target of rapamycin (PI3K/Akt/mTOR) pathway might contribute to the development of resistance to HER2-targeted therapies. Several inhibitors of this pathway are under investigation in this disease setting and phase 3 data for everolimus in combination with trastuzumab and chemotherapy in trastuzumab-refractory, advanced disease are promising. In this review, molecular mechanisms underlying resistance to HER2-targeted therapies are considered and evidence for strategies to manage resistance is evaluated, including the use of inhibitors of the PI3K/Akt/mTOR pathway.

Critical roles of specimen type and temperature before and during fixation in the detection of phosphoproteins in breast cancer tissues

The most efficient approach for therapy selection to inhibit the deregulated kinases in cancer tissues is to measure their phosphorylation status prior to the treatment. The aim of our study was to evaluate the influence of pre-analytical parameters (cold ischemia time, temperature before and during tissue fixation, and sample type) on the levels of proteins and phosphoproteins in breast cancer tissues, focusing on the PI3 kinase/AKT pathway. The BALB-neuT mouse breast cancer model expressing HER2 and pAKT proteins and human biopsy and resection specimens were analyzed. By using quantitative reverse phase protein arrays (RPPA), 9 proteins and 16 phosphoproteins relevant to breast cancer biology were assessed. Cold temperatures before and during fixation resulted in a marked improvement in the preservation of the reactivity of biological markers (eg, ER, HER2) in general and, specifically, pHER2 and pAKT. Some phosphoproteins, eg, pHER2 and pAKT, were more sensitive to prolonged cold ischemia times than others (eg, pS6RP and pSTAT5). By comparing the phosphoprotein levels in core needle biopsies with those in resection specimens, we found a marked decrease in many phosphoproteins in the latter. Cold conditions can improve the preservation of proteins and phosphoproteins in breast cancer tissues. Biopsies ≤ 1 mm in size are the preferred sample type for assessing the activity of deregulated kinases for personalized cancer treatments because the phosphoprotein levels are better preserved compared with resection specimens. Each potential new (phospho)protein biomarker should be tested for its sensitivity to pre-analytical processing prior to the development of a diagnostic assay.

Luminal breast cancer metastases and tumor arousal from dormancy are promoted by direct actions of estradiol and progesterone on the malignant cells

Introduction

Luminal, estrogen receptor-positive (ER⁺) breast cancers can metastasize but lie dormant for years before recurrences prove lethal. Understanding the roles of estrogen (E) or progestin (P) in development of luminal metastases or in arousal from dormancy is hindered by few preclinical models. We have developed such models.

Methods

Immunocompromised, ovariectomized (ovx’d) mice were intracardiac-injected with luminal or basal human breast cancer cells. Four lines were tested: luminal ER⁺PR⁺ cytokeratin 5-negative (CK5⁻) E3 and MCF-7 cells, basal ER⁻PR⁻CK5⁺ estrogen withdrawn-line 8 (EWD8) cells, and basal ER⁻PR⁻CK5⁻ MDA-MB-231 cells. Development of micrometastases or macrometastases was quantified in ovx’d mice and in mice supplemented with E or P or both. Metastatic deposits were analyzed by immunohistochemistry for luminal, basal, and proliferation markers.

Results

ER⁻PR⁻ cells generated macrometastases in multiple organs in the absence or presence of hormones. By contrast, ovx’d mice injected with ER⁺PR⁺ cells appeared to be metastases-free until they were supplemented with E or E+P. Furthermore, unlike parental ER⁺PR⁺CK5⁻ cells, luminal metastases were heterogeneous, containing a significant (6% to 30%) proportion of non-proliferative ER⁻PR⁻CK5⁺ cells that would be chemotherapy-resistant. Additionally, because these cells lack receptors, they would also be endocrine therapy-resistant. With regard to ovx’d control mice injected with ER⁺PR⁺ cells that appeared to be metastases-free, systematic pathologic analysis of organs showed that some harbor a reservoir of dormant micrometastases that are ER⁺ but PR⁻. Such cells may also be endocrine therapy- and chemotherapy-resistant. Their emergence as macrometastases can be triggered by E or E+P restoration.

Conclusions

We conclude that hormones promote development of multi-organ macrometastases in luminal disease. The metastases display a disturbing heterogeneity, containing newly emergent ER⁻PR⁻ subpopulations that would be resistant to endocrine therapy and chemotherapy. Similar cells are found in luminal metastases of patients. Furthermore, lack of hormones is not protective. While no overt metastases form in ovx’d mice, luminal tumor cells can seed distant organs, where they remain dormant as micrometastases and sheltered from therapies but arousable by hormone repletion. This has implications for breast cancer survivors or women with occult disease who are prescribed hormones for contraception or replacement purposes.

Electronic supplementary material

The online version of this article (doi:10.1186/s13058-014-0489-4) contains supplementary material, which is available to authorized users.

Comparison of the 2007 and 2013 ASCO/CAP evaluation systems for HER2 amplification in breast cancer

It has been proven that chromosome 17 centromere (CEP17) amplification causes misleading human epidermal growth factor receptor 2 (HER2) gene fluorescence in situ hybridization (FISH) results, precluding anti-HER2-based therapy in some patients with breast carcinoma. We used the 2013 American Society of Clinical Oncology/College of American Pathologists (ASCO/CAP) scoring criteria to evaluate HER2 amplification status in 175 cases of breast carcinoma with chromosome 17 polysomy. We used immunohistochemistry (IHC) to determine the HER2 amplification status, and 2-color FISH to detect CEP17, and reviewed the results of initial evaluation using the 2007 ASCO/CAP criteria. Of the 175 cases, 17, 95, and 63 were IHC 0/1+, 2+, and 3+, respectively. Evaluation of IHC HER2 status according to the 2013 ASCO/CAP criteria identified significantly more HER2-positive cases compared to cases evaluated using the 2007 criteria (p<0.05). When the FISH results were evaluated in parallel with the 2013 criteria, we found that 22 cases were not HER2-negative despite the presence of polysomy 17, which, according to the 2013 criteria, indicates HER2-positive status. Our findings indicate that in breast carcinoma, HER2 status in the presence of polysomy 17 may vary with the scoring criteria used. In turn, performing FISH and evaluating samples using the 2013 ASCO/CAP criteria means that more patients with breast cancer may be appropriate for targeted treatment with trastuzumab, potentially improving their outcome.

Current Approaches and Emerging Directions in HER2-resistant Breast Cancer

Human epidermal growth factor receptor-2 (HER2) is overexpressed in up to 30% of breast cancers; HER2 overexpression is indicative of poor prognosis. Trastuzumab, an anti-HER2 monoclonal antibody, has led to improved outcomes in patients with HER2-positive breast cancer, including improved overall survival in adjuvant and first-line settings. However, a large proportion of patients with breast cancer have intrinsic resistance to HER2-targeted therapies, and nearly all become resistant to therapy after initial response. Elucidation of underlying mechanisms contributing to HER2 resistance has led to development of novel therapeutic strategies, including those targeting HER2 and downstream pathways, heat shock protein 90, telomerase, and vascular endothelial growth factor inhibitors. Numerous clinical trials are ongoing or completed, including phase 3 data for the mammalian target of rapamycin inhibitor everolimus in patients with HER2-resistant breast cancer. This review considers the molecular mechanisms associated with HER2 resistance and evaluates the evidence for use of evolving strategies in patients with HER2-resistant breast cancer.

A review on the role of L-carnitine in the management of tamoxifen side effects in treated women with breast cancer

L-carnitine is an antioxidant and is found to be a protective agent against many diseases including cancer. This review illustrates the possible role of L-carnitine as an add-on therapy to breast cancer patients maintained on tamoxifen. The objectives of carnitine treatment are diverse: improving tamoxifen-related side effects, offering better cancer prognosis by reducing the risk of developing cancer recurrence or metastasis, and modulating the growth factors which may be, in part, a prospective illustration to overcome tamoxifen resistance. So, it could be recommended to supplement L-carnitine to breast cancer patients starting tamoxifen treatment.

Prognostic role of lemur tyrosine kinase-3 germline polymorphisms in adjuvant gastric cancer in Japan and the United States

Lemur tyrosine kinase-3 (LMTK3) was recently identified as an estrogen receptor (ER)-α modulator related to endocrine therapy resistance, and its polymorphisms rs9989661 (T>C) T/T genotype and rs8108419 (G>A) G/G or A/G genotype predicted improved outcomes in breast cancer. Because different predominant ER distributions link to breast and gastric cancer and little is known of the prognostic role of LMTK3 in gastric cancer, this study was carried out to clarify the prognostic role of these polymorphisms in gastric cancer. One-hundred and sixty-nine Japanese and 137 U.S. patients with localized gastric adenocarcinoma were enrolled. Genomic DNA was extracted from blood or tissue, and all samples were analyzed by PCR-based direct DNA sequencing. Overall, these polymorphisms were not associated with survival in both cohorts. When gender was considered, in multivariate analysis, harboring rs9989661 T/T genotype was associated with disease-free survival [HR, 4.37; 95% confidence interval (CI), 2.08-9.18; P < 0.0001] and overall survival (OS; HR, 3.69; 95% CI, 1.65-8.24; P = 0.0014) in the Japanese males and time to recurrence (HR, 7.29; 95% CI, 1.07-49.80; P = 0.043) in the U.S. females. Meanwhile, harboring rs8108419 G/G genotype was associated with OS in the Japanese females (HR, 3.04; 95% CI, 1.08-8.56; P = 0.035) and the U.S. males (HR, 3.39; 95% CI, 1.31-8.80; P = 0.012). The prognostic role of these polymorphisms may be negative in gastric cancer. These findings suggest that the estrogen pathway may play a prognostic role in patients with gastric cancer but this may be dependent on the regional differences both in physiology and genetic alterations of gastric cancer.

New strategy for monitoring targeted therapy: molecular imaging

Targeted therapy is becoming an increasingly important component in the treatment of cancer. How to accurately monitor targeted therapy has been crucial in clinical practice. The traditional approach to monitor treatment through imaging has relied on assessing the change of tumor size by refined World Health Organization criteria, or more recently, by the Response Evaluation Criteria in Solid Tumors. However, these criteria, which are based on the change of tumor size, show some limitations for evaluating targeted therapy. Currently, genetic alterations are identified with prognostic as well as predictive potential concerning the use of molecularly targeted drugs. Conversely, considering the limitations of invasiveness and the issue of expression heterogeneity, molecular imaging is better able to assay in vivo biologic processes noninvasively and quantitatively, and has been a particularly attractive tool for monitoring treatment in clinical cancer practice. This review focuses on the applications of different kinds of molecular imaging including positron emission tomography-, magnetic resonance imaging-, ultrasonography-, and computed tomography-based imaging strategies on monitoring targeted therapy. In addition, the key challenges of molecular imaging are addressed to successfully translate these promising techniques in the future.

Overcoming resistance and restoring sensitivity to HER2-targeted therapies in breast cancer

BACKGROUND

Approximately 15%-23% of breast cancers overexpress human epidermal growth factor receptor 2 (HER2), which leads to the activation of signaling pathways that stimulate cell proliferation and survival. HER2-targeted therapy has substantially improved outcomes in patients with HER2-positive breast cancer. However, both de novo and acquired resistance are observed.

DESIGN

A literature search was performed to identify proposed mechanisms of resistance to HER2-targeted therapy and identified novel targets in clinical development for treating HER2-resistant disease.

RESULTS

Proposed HER2-resistance mechanisms include impediments to HER2-inhibitor binding, signaling through alternative pathways, upregulation of signaling pathways downstream of HER2, and failure to elicit an appropriate immune response. Although continuing HER2 inhibition beyond progression may provide an additional clinical benefit, the availability of novel therapies targeting different mechanisms of action could improve outcomes. The developmental strategy with the most available data is targeting the phosphatidylinositol 3-kinase/protein kinase B/mammalian target of rapamycin (mTOR) pathway. The oral mTOR inhibitor everolimus has shown promising activity in combination with chemotherapy and trastuzumab in trastuzumab-refractory, advanced breast cancer.

CONCLUSIONS

Non-HER2-targeted therapy is a promising means of overcoming resistance to HER2-targeted treatment. Ongoing clinical studies will provide additional information on the efficacy and safety of novel targeted therapies in HER2-resistant advanced breast cancer.

Quantitative assessment of effect of preanalytic cold ischemic time on protein expression in breast cancer tissues

BACKGROUND

Companion diagnostic tests can depend on accurate measurement of protein expression in tissues. Preanalytic variables, especially cold ischemic time (time from tissue removal to fixation in formalin) can affect the measurement and may cause false-negative results. We examined 23 proteins, including four commonly used breast cancer biomarker proteins, to quantify their sensitivity to cold ischemia in breast cancer tissues.

METHODS

A series of 93 breast cancer specimens with known time-to-fixation represented in a tissue microarray and a second series of 25 matched pairs of core needle biopsies and breast cancer resections were used to evaluate changes in antigenicity as a function of cold ischemic time. Estrogen receptor (ER), progesterone receptor (PgR), HER2 or Ki67, and 19 other antigens were tested. Each antigen was measured using the AQUA method of quantitative immunofluorescence on at least one series. All statistical tests were two-sided.

RESULTS

We found no evidence for loss of antigenicity with time-to-fixation for ER, PgR, HER2, or Ki67 in a 4-hour time window. However, with a bootstrapping analysis, we observed a trend toward loss for ER and PgR, a statistically significant loss of antigenicity for phosphorylated tyrosine (P = .0048), and trends toward loss for other proteins. There was evidence of increased antigenicity in acetylated lysine, AKAP13 (P = .009), and HIF1A (P = .046), which are proteins known to be expressed in conditions of hypoxia. The loss of antigenicity for phosphorylated tyrosine and increase in expression of AKAP13, and HIF1A were confirmed in the biopsy/resection series.

CONCLUSIONS

Key breast cancer biomarkers show no evidence of loss of antigenicity, although this dataset assesses the relatively short time beyond the 1-hour limit in recent guidelines. Other proteins show changes in antigenicity in both directions. Future studies that extend the time range and normalize for heterogeneity will provide more comprehensive information on preanalytic variation due to cold ischemic time.

MicroRNA-mediated downregulation of mTOR/FGFR3 controls tumor growth induced by Src-related oncogenic pathways

The tyrosine kinase c-Src is upregulated in various human cancers, but the molecular mechanisms underlying c-Src-mediated tumor growth remain unclear. Here we examined the involvement of microRNAs in the c-Src-mediated tumor growth. Microarray profiling revealed that c-Src activation downregulates a limited set of microRNAs, including miR-99a, which targets oncogenic mammalian target of rapamycin (mTOR) and fibroblast growth factor receptor 3 (FGFR3). Re-expression of miR-99a suppressed tumor growth of c-Src-transformed cells, and this effect was restored by the overexpression of mTOR. The downregulation of miR-99a was also observed in epidermal growth factor- and Ras-transformed cells, and it was suppressed by inhibiting the mitogen-activated protein kinase (MAPK) pathway. Furthermore, miR-99a downregulation is associated with mTOR/FGFR3 upregulation in various human lung cancer cells/tissues. The tumorigenicity of these cells was suppressed by the introduction of miR-99a. These findings suggest that the miR-99a-mTOR/FGFR3 pathway is crucial for controlling tumor growth in a wide range of human cancers that harbor upregulation of the Src-related oncogenic pathways.