The impact of erythropoiesis-stimulating agents administration concomitantly with adjuvant anti-HER2 treatments on the outcomes of patients with early breast cancer: a sub-analysis of the ALTTO study.

PURPOSE: To assess whether erythropoiesis-stimulating agents (ESA) administration impacts the outcomes of patients with HER2-positive early breast cancer (EBC). METHODS: ALTTO (NCT00490139) patients were categorized by ESA use during adjuvant anti-HER2 treatment. Disease-free-survival (DFS), overall survival (OS), and time-to-distant recurrence (TTDR) were analyzed by ESA administration, with subgroup analyses according to prognostic factors. Log-rank tests and Cox modeling were performed. Adverse events (AEs) of ESA-interest were compared. RESULTS: Among 8381 patients recruited in ALTTO, 123 (1.5%) received ESA concomitantly with study treatment. The median age of patients receiving ESA was 54 years, 39.0% premenopausal, most had tumor size > 2 cm (56.9%), node-positive (58.5%), and positive estrogen receptor expression (61.8%). Median follow-up was shorter in the ESA group [6.1 years (IQR 5.3-7.0) vs. 6.9 years (6.0-7.1); p < 0.001]. There was no DFS difference by ESA administration (log-rank p = 0.70), with 3- and 7-year DFS of 89.2% (95% CI 81.8-93.8%) and 81.6% (71.4-88.5%) in ESA group vs. 88.3% (87.6-89.0%) and 80.0% (79.1-80.9%) in No-ESA group. In subgroup analyses, the interaction of ESA administration with menopausal status was statistically significant (unadjusted p = 0.024; stratified p = 0.033), favoring premenopausal women receiving ESA. We observed no significant association of ESA administration with OS (log-rank p = 0.57; 7-year OS in ESA 88.6% vs. 90.0% in non-ESA) or TTDR. ESA-interest AEs were experienced by eight (6.5%) patients receiving ESA and 417 (5.1%) in the No-ESA group (p = 0.41). CONCLUSION: ESA administration to patients receiving adjuvant anti-HER2 treatment for HER2-positive EBC was safe and not associated with a negative impact on survival outcomes.

Clinical Treatment Score Post-5 Years (CTS5) and Late Recurrence Risk in Hormone Receptor-Positive, HER2-Positive Breast Cancer.

BACKGROUND: The Clinical Treatment Score post-5 years (CTS5) is a risk stratification tool used to determine the risk of late recurrence in hormone receptor-positive (HR+), HER2-negative breast cancer (BC). Limited data exist on its use in HR+, HER2-positive (HER2+) BC. PATIENTS AND METHODS: CTS5 was evaluated in HR+, HER2+ BC in the North Central Cancer Treatment Group (NCCTG) N9831 (Alliance) and NSABP B-31 (NRG) trials. RESULTS: A total of 1,862 patients with HR+, HER2+ BC without recurrence 5 years after enrollment were included. Overall, the CTS5 score was significantly associated with recurrence-free survival (RFS), with a hazard ratio (HR) of 1.35 (95% CI, 1.12-1.63; P=.002), but did not reach statistical significance in patients who received trastuzumab (n=829; HR, 1.29; 95% CI, 0.98-1.71; P=.07). CTS5 risk category was not significantly associated with RFS. In patients who received trastuzumab, other variables used in CTS5, including patient age and tumor size, were not significantly associated with RFS. N3 was significantly associated with worse outcomes (HR, 1.86; 95% CI, 1.09-3.17; P=.02) compared with N0-N1. Paradoxically, higher tumor grade was associated with better outcomes after 5 years in the multivariate analysis (HR, 0.71; 95% CI, 0.50-1.00; P=.05). The incidence of recurrences or deaths between years 5 to 10 was 10.6% in the CTS5 low-risk category, 5.6% in the intermediate-risk category, and 9.8% in the high-risk category. CONCLUSIONS: The CTS5 model does not accurately predict the risk of late recurrence in HR+, HER2+ BC treated with adjuvant trastuzumab in the N9831 and B-31 trials. This study underlines the need to develop a new prognostic model to better delineate the risk of late recurrence in patients with HR+, HER2+ BC receiving adjuvant trastuzumab. CLINICALTRIALS: gov identifiers: NCT00005970 (NCCTG N9831) and NCT00004067 (NRG/NSABP B-31).

CCR5 activation and endocytosis in circulating tumor-derived cells isolated from the blood of breast cancer patients provide information about clinical outcome.

BACKGROUND: CCR5 is a motility chemokine receptor implicated in tumor progression, whose activation and subsequent endocytosis may identify highly aggressive breast cancer cell subtypes likely to spread into the circulatory system. METHODS: The MDA-MB-231 cell line was used to model and visualize CCR5 activation by stimulation with RANTES, in an effort to quantify CCR5 endocytosis from the cell surface to the perinuclear space. CCR5 expression was then examined in tumor-associated cells (TACs), consisting of circulating tumor cells and circulating stromal cells, isolated from the peripheral blood of 54 metastatic breast cancer (mBC) patients to evaluate these CCR5 pooling patterns as they relate to progression and survival over 2 years. RESULTS: In MB231 experiments, it was observed that CCR5 formed ~ 1 micron clusters identified as "CCR5 pools" on the surface of the cell, which in the presence of RANTES were endocytosed and translocated to the cell cytoplasm. When TACs from patients were analyzed, CCR5 pools were observed on the cell surface and translocating to the nuclear area, with CCR5 also having a positive statistical correlation between increased numbers of TACs and increased CCR5 pools on the cells. Further, it was determined that patients with very high numbers of CCR5 (> 10 CCR5 pools), specifically in the circulating stromal cells, were associated with worse progression-free survival (hazard ratio = 4.5, p = 0.002) and worse overall survival (hazard ratio = 3.7, p = 0.014). CONCLUSIONS: Using a liquid biopsy approach, we evaluated two populations of tumor-associated cells emanating from primary tumors, with data suggesting that upregulation of the motility chemokine CCR5 in TACs provides clinically relevant opportunities for treating and tracking drug targetable receptors in mBC.

Outcomes of patients with small and node-negative HER2-positive early breast cancer treated with adjuvant chemotherapy and anti-HER2 therapy-a sub-analysis of the ALTTO study.

BACKGROUND: Patients with small node-negative HER2-positive breast cancer are commonly treated with paclitaxel and 1 year of adjuvant trastuzumab. We performed a sub-analysis of the ALTTO trial to explore the long-term outcomes of patients with small node-negative tumours. METHODS: The ALTTO trial randomised 8381 patients with early HER2-positive BC treated with adjuvant chemotherapy (anthracycline/taxane- or taxane/carboplatin-based), to trastuzumab (T), lapatinib (L), their sequence (T → L) or their combination (L + T). Patients with tumours ≤3 cm and node-negative were included in this sub-analysis. RESULTS: A total of 2821 patients were analysed (median follow-up of 7 years). The median age was 52 years, and most patients had tumours ≤2 cm (64.3%). The 7-year disease-free survival (DFS) was 88.1% (95% CI: 86.7-89.3%). DFS was similar for arms T, T + L and T⟶L and significantly lower for arm L (stratified log-rank P = 0.031). The 7-year overall survival rate was 95.9% (95% CI: [95.0-96.6%) and the 7-year time-to-distant recurrence was 93.4% (95% CI: 92.3-94.4%). CONCLUSION: With most patients treated with anthracycline-based regimens, ALTTO shows that patients with small tumours treated with trastuzumab and concomitant chemotherapy have excellent long-term outcomes, similar to those of the APT trial. TRIAL REGISTRATION: Clinicaltrials.gov identifier NCT00490139.

Beta 2-Adrenergic Receptor in Circulating Cancer-Associated Cells Predicts for Increases in Stromal Macrophages in Circulation and Patient Survival in Metastatic Breast Cancer.

The usage of beta blockers in breast cancer (BC) patients is implicated in the reduction in distant metastases, cancer recurrence, and cancer mortality. Studies suggest that the adrenergic pathway is directly involved in sympathetic-driven hematopoietic activation of pro-tumor microenvironmental proliferation and tumor cell trafficking into the circulation. Cancer-associated macrophage-like cells (CAMLs) are pro-tumor polynucleated monocytic cells of hematopoietic origin emanating from tumors which may aid in circulating tumor cell (CTC) dissemination into the circulation. We examined the linkage between Beta-2 adrenergic receptor (B2AR) signaling in CAMLs and CTCs by establishing expression profiles in a model BC cell line (MDA-MB-231). We compared the model to CAMLs and CTCs found in patents. Although internalization events were observed in patients, differences were found in the expression of B2AR between the tumor cell lines and the CAMLs found in patients. High B2AR expression on patients' CAMLs was correlated with significantly more CAMLs in the circulation (p = 0.0093), but CTCs had no numerical relationship (p = 0.1565). High B2AR CAML expression was also significantly associated with a larger size of CAMLs (p = 0.0073), as well as being significantly associated with shorter progression-free survival (p = 0.0097) and overall survival (p = 0.0265). These data suggest that B2AR expression on CAMLs is closely related to the activation, intravasation, and growth of CAMLs in the circulation.

Long-term cardiac outcomes of patients with HER2-positive breast cancer treated in the adjuvant lapatinib and/or trastuzumab Treatment Optimization Trial.

BACKGROUND: Cardiotoxicity is the most significant adverse event associated with trastuzumab (T), the main component of HER2-positive breast cancer (BC) treatment. Less is known about the cardiotoxicity of dual HER2 blockade with T plus lapatinib (L), although this regimen is used in the metastatic setting. METHODS: This is a sub-analysis of the ALTTO trial comparing adjuvant treatment options for patients with early HER2-positive BC. Patients randomised to either T or concomitant T + L were eligible. Cardiac events (CEs) rates were compared according to treatment arm. RESULTS: With 6.9 years of median follow-up (FU) and 4190 patients, CE were observed in 363 (8.6%): 166 (7.9%) of patient in T + L arm vs. 197 (9.3%) in T arm (OR = 0.85 [95% CI, 0.68-1.05]). During anti-HER2 treatment 270 CE (6.4%) occurred while 93 (2.2%) were during FU (median time to onset = 6.6 months [IQR = 3.4-11.7]). While 265 CEs were asymptomatic (73%), 94 were symptomatic (26%) and four were cardiac deaths (1%). Recovery was observed in 301 cases (83.8%). Identified cardiac risk factors were: baseline LVEF < 55% (vs > 64%, OR 3.1 [95% CI 1.54-6.25]), diabetes mellitus (OR 1.85 [95% CI 1.25-2.75]), BMI > 30 kg/m2 (vs < 25 mg/kg2, OR 2.21 [95% CI 1.40-3.49]), cumulative dose of doxorubicin ≥240 mg/m2 (OR 1.36 [95% CI 1.01-1.82]) and of epirubicin≥ 480 mg/m2 (OR 2.33 [95% CI 1.55-3.51]). CONCLUSIONS: Dual HER2 blockade with T + L is a safe regimen from a cardiac perspective, but cardiac-focused history for proper patient selection is crucial. TRIAL REGISTRATION NUMBER: ClinicalTrials.gov Identifier: NCT00490139 (registration date: 22/06/2007); EudraCT Number: 2006-000562-36 (registration date: 04/05/2007); Sponsor Protocol Number: BIG2-06 /EGF106708/N063D.

Durable Complete Response With Immune Checkpoint Inhibitor in Breast Cancer With High Tumor Mutational Burden and APOBEC Signature.

Increasing data support the importance of preexisting host immune response and neoantigen burden for determining response to immune checkpoint inhibitors (ICIs). In lung cancer and melanoma, tumor mutational burden (TMB) has emerged as an independent biomarker for ICI response. However, the significance of TMB in breast cancer, particularly in the context of PD-L1 negativity, remains unclear. This report describes a patient with HER2-negative breast cancer with high TMB and an apolipoprotein B mRNA editing enzyme, catalytic polypeptide-like (APOBEC) trinucleotide signature; her disease was refractory to multiple lines of treatments but achieved durable complete response using ICIs and capecitabine. Additional analysis of the tumor revealed a low amount of stromal tumor-infiltrating lymphocytes (sTILs) and PD-L1 negativity, reflecting a poor preexisting host immune response. In collaboration with Foundation Medicine, comprehensive genomic profiling from 14,867 patients with breast cancer with the FoundationOne test was evaluated. Using the cutoff of ≥10 mutations/megabase (mut/Mb) for high TMB, PD-L1 positivity and TMB-high populations were not significantly overlapping (odds ratio, 1.02; P=.87). Up to 79% of TMB-high tumors with >20 mut/Mb were PD-L1-negative. Our study highlights that despite having low TILs and PD-L1 negativity, some patients may still experience response to ICIs.

Dissecting the effect of hormone receptor status in patients with HER2-positive early breast cancer: exploratory analysis from the ALTTO (BIG 2-06) randomized clinical trial.

PURPOSE: Limited evidence exists on the impact of hormone receptor (HR) status to counsel HER2-positive early breast cancer patients receiving adjuvant anti-HER2 therapy. METHODS: ALTTO (BIG 2-06) was an international, intergroup, open-label, randomized phase III trial in HER2-positive early breast cancer patients randomized to receive 1 year of trastuzumab and/or lapatinib. HER2, estrogen and progesterone receptors were centrally tested for all patients. We investigated the impact of HR status on prognosis, risk of disease-free survival (DFS) events over time, patterns of first DFS events, and factors associated with risk of DFS events overall, in years 0-5 and 6-8. RESULTS: Out of 6273 patients included in this analysis, 3603 (57.4%) had HR-positive tumors. Median follow-up was 6.93 years. Five-year and 8-year DFS were 86% and 80% in patients with HR-positive disease, and 83% and 79% in those with HR-negative tumors, respectively. Mean annual hazards of recurrence in years 0-5 were 3% in patients with HR-positive disease and 4% in those with HR-negative tumors, while in years 6-8 they were 3% and 2%, respectively. Distribution of first DFS event in years 6-8 (P = 0.005) and type of first distant recurrence (P < 0.001) were significantly different between the two groups. Risk factors for DFS events overall, in years 0-5, and 6-8 were different in patients with HR-positive and HR-negative tumors. CONCLUSIONS: HER2-positive early breast cancer is characterized by the presence of two diseases with distinct natural history based on HR status requiring the development of different follow-up strategies and future de-escalation and escalation clinical trials.

High-Sensitivity Troponin T and NT-proBNP Kinetics in Breast Cancer Chemotherapy.

BACKGROUND/AIMS: Doxorubicin (DOX) and trastuzumab (TRA) are associated with cardiac dysfunction. METHOD: High-sensitivity troponin T (hs-TnT) and brain natriuretic peptide attached to the amino acid N-terminal fragment in the prohormone (NT-proBNP) were measured before and on days +1, +2, +3, and +7 during cycles 1 and 2 of therapy with DOX or TRA in breast cancer patients. RESULTS: Five of eleven DOX-treated women, compared with 2/11 TRA-treated women, had undetectable baseline hs-TnT. By day +1 of cycle 2, all the DOX-treated women (p = 0.03) but only 7/11 TRA-treated women (p = ns) had detectible hs-TnT. Time to peak was 1-2 days for both groups. In the DOX-treated women, hs-TnT showed significant peaks from precycle baseline, increases in precycle 1 to precycle 2 levels, and a cycle 1 to cycle 2 peak and area under the curve (AUC). hs-TnT increased from precycle (1, 4.6 ± 6.3 pg/mL) to a cycle 2 peak of 16.1 ± 15.0 pg/mL (p < 0.002). No increases were seen with the TRA treatment. Transient posttreatment increases in NT-proBNP were seen after both therapies. CONCLUSION: DOX was associated with increased pretreatment baseline, peak, and AUC hs-TnT levels. Both DOX and TRA acutely perturb NT-proBNP. Assessment of pre- and posttreatment hs-TnT could be a means of quantifying cumulative myocardial injury in the course of chemotherapy.

Circulating giant macrophages as a potential biomarker of solid tumors.

Tumor-associated macrophages (TAMs) derived from primary tumors are believed to facilitate circulating tumor cell (CTC) seeding of distant metastases, but the mechanisms of these processes are poorly understood. Although many studies have focused on the migration of CTCs, less attention has been given to TAMs that, like CTCs, derive from tumor sites. Using precision microfilters under low-flow conditions, we isolated circulating cancer-associated macrophage-like cells (CAMLs) from the peripheral blood of patients with breast, pancreatic, or prostate cancer. CAMLs, which are not found in healthy individuals, were found to express epithelial, monocytic, and endothelial protein markers and were observed bound to CTCs in circulation. These data support the hypothesis that disseminated TAMs can be used as a biomarker of advanced disease and suggest that they have a participatory role in tumor cell migration.

Mitosis in circulating tumor cells stratifies highly aggressive breast carcinomas.

BACKGROUND: Enumeration of circulating tumor cells (CTCs) isolated from the peripheral blood of breast cancer patients holds promise as a clinically relevant, minimally invasive diagnostic test. However, CTC utility has been limited as a prognostic indicator of survival by the inability to stratify patients beyond general enumeration. In comparison, histological biopsy examinations remain the standard method for confirming malignancy and grading malignant cells, allowing for cancer identification and then assessing patient cohorts for prognostic and predictive value. Typically, CTC identification relies on immunofluorescent staining assessed as absent/present, which is somewhat subjective and limited in its ability to characterize these cells. In contrast, the physical features used in histological cytology comprise the gold standard method used to identify and preliminarily characterize the cancer cells. Here, we superimpose the methods, cytologically subtyping CTCs labeled with immunohistochemical fluorescence stains to improve their prognostic value in relation to survival. METHODS: In this single-blind prospective pilot study, we tracked 36 patients with late-stage breast cancer over 24 months to compare overall survival between simple CTC enumeration and subtyping mitotic CTCs. A power analysis (1-ß = 0. 9, α = 0.05) determined that a pilot size of 30 patients was sufficient to stratify this patient cohort; 36 in total were enrolled. RESULTS: Our results confirmed that CTC number is a prognostic indicator of patient survival, with a hazard ratio 5.2, p = 0.005 (95 % CI 1.6-16.5). However, by simply subtyping the same population based on CTCs in cytological mitosis, the hazard ratio increased dramatically to 11.1, p < 0.001 (95 % CI 3.1-39.7). CONCLUSIONS: Our data suggest that (1) mitotic CTCs are relativity common in aggressive late-stage breast cancer, (2) mitotic CTCs may significantly correlate with shortened overall survival, and (3) larger and more defined patient cohort studies are clearly called for based on this initial pilot study.

Nonamplification ERBB2 genomic alterations in 5605 cases of recurrent and metastatic breast cancer: An emerging opportunity for anti-HER2 targeted therapies.

BACKGROUND: Activating, nonamplification ERBB2 mutations (ERBB2mut) are not detected by immunohistochemistry (IHC) or fluorescence in situ hybridization (FISH), but are detected by DNA sequencing and may predict clinical responses to human epidermal growth factor receptor (HER2)-targeted therapy. The authors queried 5605 advanced/metastatic breast cancers (mBC) to uncover the frequency of ERBB2mut genomic alterations. Clinical responses to anti-HER2 therapeutics were identified. METHODS: DNA was extracted from 40 µm of formalin-fixed paraffin-embedded (FFPE) sections. Comprehensive genomic profiling (CGP) was used to evaluate up to 315 genes (592× mean coverage depth). Results were analyzed for base substitutions, short indels, copy number changes, and selected rearrangements. RESULTS: Of 5605 cases, 698 (12.5%) featured ERBB2 alterations, including 596 (10.6%) ERBB2 amplifications (ERBB2amp) and 138 (2.4%) ERBB2mut; 38 cases (0.7%) had co-occurring ERBB2amp and ERBB2mut. ERBB2mut predominantly affected the kinase (124 cases; 90%) or extracellular (15 cases; 11%) domains. Both primary BC (52 cases; 38%) and metastatic site biopsies (86 cases; 62%) were found to harbor ERBB2mut, which were distributed across carcinoma not otherwise specified (NOS) (69 cases; 50%), invasive ductal carcinoma (IDC) (40 cases; 29%), invasive lobular carcinoma (ILC) (27 cases; 20%), and mucinous mBC (2 cases; 1%). Genes commonly coaltered with ERBB2 were tumor protein 53 (TP53) (49%); phosphatidylinositol 3-kinase catalytic subunit alpha (PIK3CA) (42%); cadherin 1, type 1 (CDH1) (37%); MYC (17%); and cyclin D1 protein (CCND1) (16%). CDH1 mutations were enriched in ERBB2mut mBC (P<0.0006) and associated with recurrent mBC. Selected patients with ERBB2mut, without ERBB2amp, who responded to anti-HER2 targeted therapies are presented herein. CONCLUSIONS: Within this large series, 1.8% of cases harbored ERBB2mut, which are undetectable by standard-of-care IHC or FISH tests. Metastatic BC driven by ERBB2mut respond to anti-HER2 targeted therapies, and expanding clinical trials designed to detect ERBB2mut by CGP and optimize targeted treatments are warranted. Cancer 2016. © 2016 American Cancer Society. Cancer 2016;122:2654-2662. © 2016 American Cancer Society.

The RUNX2 Transcription Factor Negatively Regulates SIRT6 Expression to Alter Glucose Metabolism in Breast Cancer Cells.

Activation of genes promoting aerobic glycolysis and suppression of mitochondrial oxidative phosphorylation is one of the hallmarks of cancer. The RUNX2 transcription factor mediates breast cancer (BC) metastasis to bone and is regulated by glucose availability. But, the mechanisms by which it regulates glucose metabolism and promotes an oncogenic phenotype are not known. RUNX2 expression in luminal BC cells correlated with lower estrogen receptor-α (ERα) levels, anchorage-independent growth, expression of glycolytic genes, increased glucose uptake, and sensitivity to glucose starvation, but not to inhibitors of oxidative phosphorylation. Conversely, RUNX2 knockdown in triple-negative BC cells inhibited mammosphere formation and glucose dependence. RUNX2 knockdown resulted in lower LDHA, HK2, and GLUT1 glycolytic gene expression, but upregulation of pyruvate dehydrogenase-A1 (PDHA1) mRNA and enzymatic activity, which was consistent with lower glycolytic potential. The NAD-dependent histone deacetylase, SIRT6, a known tumor suppressor, was a critical regulator of these RUNX2-mediated metabolic changes. RUNX2 expression resulted in elevated pAkt, HK2, and PDHK1 glycolytic protein levels that were reduced by ectopic expression of SIRT6. RUNX2 also repressed mitochondrial oxygen consumption rates (OCR), a measure of oxidative phosphorylation (respiration). Overexpression of SIRT6 increased respiration in RUNX2-positive cells, but knockdown of SIRT6 in cells expressing low RUNX2 decreased respiration. RUNX2 repressed SIRT6 expression at both the transcriptional and post-translational levels and endogenous SIRT6 expression was lower in malignant BC tissues or cell lines that expressed high levels of RUNX2. These results support a hypothesis whereby RUNX2-mediated repression of the SIRT6 tumor suppressor regulates metabolic pathways that promote BC progression.

Histone deacetylase inhibitor entinostat in combination with a retinoid downregulates HER2 and reduces the tumor initiating cell population in aromatase inhibitor-resistant breast cancer.

Resistance to aromatase inhibitors (AIs) involves increased HER2. One mechanism by which HER2 may mediate resistance is through expansion of the tumor initiating cell (TIC) population. This study investigates whether combining all-trans retinoic acid (ATRA) and histone deacetylase inhibitor entinostat (ENT) can inhibit TICs and HER2 in AI-resistant cells and tumors. Modulation of cell viability and HER2 expression were assessed in AI-resistant cells treated with ATRA + ENT. Letrozole-resistant LTLT-Ca cells treated with ATRA + ENT were assayed for changes in TIC characteristics, such as TIC markers (BCRP, ALDH, and BMI-1), side population (SP), and mammosphere formation. Xenograft tumors of MCF-7Ca cells made resistant to letrozole were treated with ATRA, ATRA + letrozole, ATRA + ENT, or ATRA + ENT + letrozole. Resulting tumors were assayed for changes in TIC characteristics. Patient samples taken pre- and post-AI treatment were analyzed for changes in ERα and HER2 protein expression. Treatment with ATRA + ENT reduced HER2 expression and viability (P < 0.001) in AI-resistant cells, as well as decreased SP (P < 0.0001), mammosphere formation (P < 0.01), and expression of TIC molecular markers (P < 0.01) in LTLT-Ca. A reduction in tumor growth rate was observed in mice treated with ENT + ATRA + letrozole when compared to mice treated with single agents (P < 0.0001) or ENT + ATRA (P = 0.02). Decreased TIC characteristics, including mammosphere formation (P < 0.05), were observed in tumors from the triple combination. An increase in HER2 and downregulation in ERα protein expression was observed in patients upon resistance to AI (P < 0.005). These studies indicate that the combination of ATRA and ENT inhibits the TIC population of AI-resistant cells and may be effective in reducing tumor recurrence.

Cytometric characterization of circulating tumor cells captured by microfiltration and their correlation to the CellSearch(®) CTC test.

Recent studies reporting hundreds, to thousands, of circulating tumor cells (CTCs) in the blood of cancer patients have raised questions regarding the prevalence of CTCs, as enumerated by the CellSearch(®) CTC Test. Although CellSearch has been shown to consistently detect clinically relevant CTCs; the ability to only capture EpCAM positive cells has led to speculation that it captures limited subsets of CTCs. In contrast, alternative approaches to CTC isolation are often cited as capturing large numbers of CTCs from patient blood. Not surprisingly the number of cells isolated by alternative approaches show poor correlations when compared to CellSearch, even when accounting for EpCAM presence or absence. In an effort to address this discrepancy, we ran an exploratory method comparison study to characterize and compare the CTC subgroups captured from duplicate blood samples from 30 breast and prostate cancer patients using a microfiltration system (CellSieve™) and CellSearch. We then categorized the CellSieve Cytokeratin(CK)+/CD45-/DAPI+ cells into five morphologically distinct subpopulations for correlative analysis. Like other filtration techniques, CellSieve isolated greater numbers of CK+/CD45- cells than CellSearch. Furthermore, analysis showed low correlation between the total CK+/CD45- cells captured by these two assays, regardless of EpCAM presence. However, subgrouping of CK+/CD45-/DAPI+ cells based on distinct cytokeratin staining patterns and nuclear morphologies elucidated a subpopulation correlative to CellSearch. Using method comparison analyses, we identified a specific CTC morphology which is highly correlative between two distinct capture methods. These data suggests that although various morphologic CTCs with similar phenotypic expressions are present in the blood of cancer patients, the clinically relevant cells isolated by CellSearch can potentially be identified using non-EpCAM dependent isolation. © 2014 The Authors. Published by Wiley Periodicals, Inc.

Prolonged Response to Trastuzumab in a Patient With HER2-Nonamplified Breast Cancer With Elevated HER2 Dimerization Harboring an ERBB2 S310F Mutation.

In the current genomic era, increasing evidence demonstrates that approximately 2% of HER2-negative breast cancers, by current standard testings, harbor activating mutations of ERBB2. However, whether patients with HER2-negative breast cancer with activating mutations of ERBB2 also experience response to anti-HER2 therapies remains unclear. This case report describes a patient with HER2-nonamplified heavily pretreated breast cancer who experienced prolonged response to trastuzumab in combination with pertuzumab and fulvestrant. Further molecular analysis demonstrated that her tumors had an elevated HER2 dimerization that corresponded to ERBB2 S310F mutation. Located in the extracellular domain of the HER2 protein, this mutation was reported to promote noncovalent dimerization that results in the activation of the downstream signaling pathways. This case highlights the fact that HER2-targeted therapy may be valuable in patients harboring an ERBB2 S310F mutation.

Nonhypoxic regulation and role of hypoxia-inducible factor 1 in aromatase inhibitor resistant breast cancer.

INTRODUCTION: Although aromatase inhibitors (AIs; for example, letrozole) are highly effective in treating estrogen receptor positive (ER+) breast cancer, a significant percentage of patients either do not respond to AIs or become resistant to them. Previous studies suggest that acquired resistance to AIs involves a switch from dependence on ER signaling to dependence on growth factor-mediated pathways, such as human epidermal growth factor receptor-2 (HER2). However, the role of HER2, and the identity of other relevant factors that may be used as biomarkers or therapeutic targets remain unknown. This study investigated the potential role of transcription factor hypoxia inducible factor 1 (HIF-1) in acquired AI resistance, and its regulation by HER2. METHODS: In vitro studies using AI (letrozole or exemestane)-resistant and AI-sensitive cells were conducted to investigate the regulation and role of HIF-1 in AI resistance. Western blot and RT-PCR analyses were conducted to compare protein and mRNA expression, respectively, of ERα, HER2, and HIF-1α (inducible HIF-1 subunit) in AI-resistant versus AI-sensitive cells. Similar expression analyses were also done, along with chromatin immunoprecipitation (ChIP), to identify previously known HIF-1 target genes, such as breast cancer resistance protein (BCRP), that may also play a role in AI resistance. Letrozole-resistant cells were treated with inhibitors to HER2, kinase pathways, and ERα to elucidate the regulation of HIF-1 and BCRP. Lastly, cells were treated with inhibitors or inducers of HIF-1α to determine its importance. RESULTS: Basal HIF-1α protein and BCRP mRNA and protein are higher in AI-resistant and HER2-transfected cells than in AI-sensitive, HER2- parental cells under nonhypoxic conditions. HIF-1α expression in AI-resistant cells is likely regulated by HER2 activated-phosphatidylinositide-3-kinase/Akt-protein kinase B/mammalian target of rapamycin (PI3K/Akt/mTOR) pathway, as its expression was inhibited by HER2 inhibitors and kinase pathway inhibitors. Inhibition or upregulation of HIF-1α affects breast cancer cell expression of BCRP; AI responsiveness; and expression of cancer stem cell characteristics, partially through BCRP. CONCLUSIONS: One of the mechanisms of AI resistance may be through regulation of nonhypoxic HIF-1 target genes, such as BCRP, implicated in chemoresistance. Thus, HIF-1 should be explored further for its potential as a biomarker of and therapeutic target.