Phase II randomized study of neoadjuvant everolimus plus letrozole compared with placebo plus letrozole in patients with estrogen receptor-positive breast cancer

Safety analysis, association with response and previous treatments of everolimus and exemestane in 181 metastatic breast cancer patients: A multicenter Italian experience

PURPOSE

The everolimus and exemestane combination represents a treatment option for the endocrine sensitive metastatic breast cancer (MBC) patients. The toxicity profile reported in the Bolero 2 trial showed the feasibility in the selected patients. Few data are available for the unselected population.

METHODS

In order to evaluate the safety in the unselected population of the clinical practice and to evaluate a possible association of toxicities with previous treatments, clinical data from 181 consecutive patients were retrospectively collected.

RESULTS

Due to toxic events, everolimus dosage was reduced to 5 mg in 27% of patients. No association was found in the analysis between toxicity and number of prior therapies, neither between toxicity and response. In the multivariate analysis the previous exposure to anthracyclines for advanced disease represents the only predictive factor of developing grade ≥2 toxicity (OR = 2.85 CI 95% 1.07-7.59, p = 0.036).

CONCLUSIONS

The association of everolimus and exemestane has confirmed to be a safe and effective treatment for endocrine sensitive MBC patients even in routine clinical practice. The rate of treatment discontinuation due to toxicity is low and none association between previous number of treatments and response or between toxicity and response was found.

Everolimus downregulates estrogen receptor and induces autophagy in aromatase inhibitor-resistant breast cancer cells

Background

mTOR inhibition of aromatase inhibitor (AI)-resistant breast cancer is currently under evaluation in the clinic. Everolimus/RAD001 (Afinitor®) has had limited efficacy as a solo agent but is projected to become part of combination therapy for AI-resistant breast cancer. This study was conducted to investigate the anti-proliferative and resistance mechanisms of everolimus in AI-resistant breast cancer cells.

Methods

In this study we utilized two AI-resistant breast cancer cell lines, MCF-7:5C and MCF-7:2A, which were clonally derived from estrogen receptor positive (ER+) MCF-7 breast cancer cells following long-term estrogen deprivation. Cell viability assay, colony formation assay, cell cycle analysis and soft agar anchorage-independent growth assay were used to determine the efficacy of everolimus in inhibiting the proliferation and tumor forming potential of MCF-7, MCF-7:5C, MCF-7:2A and MCF10A cells. Confocal microscopy and transmission electron microscopy were used to evaluate LC3-II production and autophagosome formation, while ERE-luciferase reporter, Western blot, and RT-PCR analyses were used to assess ER expression and transcriptional activity.

Results

Everolimus inhibited the proliferation of MCF-7:5C and MCF-7:2A cells with relatively equal efficiency to parental MCF-7 breast cancer cells. The inhibitory effect of everolimus was due to G1 arrest as a result of downregulation of cyclin D1 and p21. Everolimus also dramatically reduced estrogen receptor (ER) expression (mRNA and protein) and transcriptional activity in addition to the ER chaperone, heat shock protein 90 protein (HSP90). Everolimus restored 4-hydroxy-tamoxifen (4OHT) sensitivity in MCF-7:5C cells and enhanced 4OHT sensitivity in MCF-7 and MCF-7:2A cells. Notably, we found that autophagy is one method of everolimus insensitivity in MCF-7 breast cancer cell lines.

Conclusion

This study provides additional insight into the mechanism(s) of action of everolimus that can be used to enhance the utility of mTOR inhibitors as part of combination therapy for AI-resistant breast cancer.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-016-2490-z) contains supplementary material, which is available to authorized users.

Ribociclib plus letrozole in early breast cancer: A presurgical, window-of-opportunity study

OBJECTIVES

Cyclin D-cyclin-dependent kinase (CDK) 4/6-inhibitor of CDK4/6-retinoblastoma (Rb) pathway hyperactivation is associated with hormone receptor-positive (HR+) breast cancer (BC). This study assessed the biological activity of ribociclib (LEE011; CDK4/6 inhibitor) plus letrozole compared with single-agent letrozole in the presurgical setting.

MATERIALS AND METHODS

Postmenopausal women (N = 14) with resectable, HR+, human epidermal growth factor receptor 2-negative (HER2-) early BC were randomized 1:1:1 to receive 2.5 mg/day letrozole alone (Arm 1), or with 400 or 600 mg/day ribociclib (Arm 2 or 3). Circulating tumor DNA and tumor biopsies were collected at baseline and, following 14 days of treatment, prior to or during surgery. The primary objective was to assess antiproliferative response per Ki67 levels in Arms 2 and 3 compared with Arm 1. Additional assessments included safety, pharmacokinetics, and genetic profiling.

RESULTS

Mean decreases in the Ki67-positive cell fraction from baseline were: Arm 1 69% (range 38-100%; n = 2), Arm 2 96% (range 78-100%; n = 6), Arm 3 92% (range 75-100%; n = 3). Decreased phosphorylated Rb levels and CDK4, CDK6, CCND2, CCND3, and CCNE1 gene expression were observed following ribociclib treatment. Ribociclib and letrozole pharmacokinetic parameters were consistent with single-agent data. The ribociclib plus letrozole combination was well tolerated, with no Grade 3/4 adverse events over the treatment.

CONCLUSION

The results suggest absence of a drug-drug interaction between ribociclib and letrozole and indicate ribociclib plus letrozole may reduce Ki67 expression in HR+, HER2- BC (NCT01919229).

Risk of mTOR inhibitors induced severe pneumonitis in cancer patients: a meta-analysis of randomized controlled trials

Background: A meta-analysis of randomized controlled trials was performed to determine the overall risk of noninfectious severe pneumonitis associated with mTOR inhibitors (mTORi) in cancer patients. Materials & methods: PubMed, EMBASE and oncology conference proceedings were searched for relevant studies. Results: A total of 8377 patients from 16 randomized controlled trials were included. The incidence of severe pneumonitis associated with mTORi was 1.7% (95% CI: 1.1–2.5%). The use of mTORi significantly increased the risk of severe pneumonitis compared with controls (odds ratio: 3.36; 95% CI: 2.20–5.12). The analysis was stratified for drug types, tumor types, controlled therapy and mTORi-based regimens, but no significant differences in odds ratios were observed. Conclusion: mTORi significantly increase the risk of severe pneumonitis in cancer patients.

Involvement of mTOR and Regulation by AMPK in Early Iodine Deficiency-Induced Thyroid Microvascular Activation

Iodine deficiency (ID) induces TSH-independent microvascular activation in the thyroid via the reactive oxygen species/nitric oxide-hypoxia-inducible factor-1α/vascular endothelial growth factor (VEGF) pathway. We hypothesized the additional involvement of mammalian target of rapamycin (mTOR) as a positive regulator of this pathway and AMP-activated protein kinase (AMPK) as a negative feedback regulator to explain the transient nature of ID-induced microvascular changes under nonmalignant conditions. mTOR and AMPK involvement was investigated using an in vitro model (human thyrocytes in primary cultures) and 2 murine models of goitrogenesis (normal NMRI and RET-PTC mice [a papillary thyroid cancer model]). In NMRI mice, ID had no effect on the phosphorylation of ribosomal S6 kinase (p70S6K), a downstream target of mTOR. However, rapamycin inhibited ID-induced thyroid blood flow and VEGF protein expression. In the RET-PTC model, ID strongly increased the phosphorylation of p70S6K, whereas rapamycin completely inhibited the ID-induced increase in p70S6K phosphorylation, thyroid blood flow, and VEGF-A expression. In vitro, although ID increased p70S6K phosphorylation, the ID-stimulated hypoxia-inducible factor/VEGF pathway was inhibited by rapamycin. Activation of AMPK by metformin inhibited ID effects both in vivo and in vitro. In AMPK-α1 knockout mice, the ID-induced increase in thyroid blood flow and VEGF-A protein expression persisted throughout the treatment, whereas both parameters returned to control values in wild-type mice after 4 days of ID. In conclusion, mTOR is required for early ID-induced thyroid microvascular activation. AMPK negatively regulates this pathway, which may account for the transient nature of ID-induced TSH-independent vascular effects under benign conditions.

Network Meta-Analysis of the Effectiveness of Neoadjuvant Endocrine Therapy for Postmenopausal, HR-Positive Breast Cancer

In clinical practice, it is necessary to define an optimal choice from many different therapeutic regimens. This study aimed to assess the efficacy and safety of neoadjuvant endocrine therapy (NET) for breast cancer patients. Randomized clinical trials were included. Nine studies comprising 2133 patients were included in the final analysis. Network meta-analysis showed that everolimus plus letrozole was more easily accepted by patients than exemestane (≥20wks) (odds ratio (OR): 856697.02, 95% confidence intervals (95%CI): 1.88 to 87242934...); exemestane (≥20wks) had worse acceptability than letrozole (OR: 0.00, 95%CI: 0.00 to 0.98). Letrozole produced a better clinical objective response (COR) than tamoxifen (OR: 1.99, 95%CI: 1.04 to 3.80). The incidence of fatigue between the anastrozole plus gefitinib group and the everolimus plus letrozole group was significantly different (OR: 0.08, 95%CI: 0.01 to 0.83). The exemestane (<20wks) plus celecoxib group had fewer hot flushes than others. Ranking showed the everolimus plus letrozole was most likely rank first in comparisons of COR and acceptability, and had a 64% possibility to rank first after stochastic multi-criteria acceptability analysis. In conclusion, our study showed that letrozole plus everolimus is the most effective treatment for postmenopausal, hormone receptor-positive breast cancer in the neoadjuvant setting.

The therapeutic potential of mTOR inhibitors in breast cancer

Rapamycin and modified rapamycins (rapalogs) have been used to prevent allograft rejection after organ transplant for over 15 years. The mechanistic target of rapamycin (mTOR) has been determined to be a key component of the mTORC1 complex which consists of the serine/threonine kinase TOR and at least five other proteins which are involved in regulating its activity. Some of the best characterized substrates of mTORC1 are proteins which are key kinases involved in the regulation of cell growth (e.g., p70S6K) and protein translation (e.g., 4E-BP1). These proteins may in some cases serve as indicators to sensitivity to rapamycin-related therapies. Dysregulation of mTORC1 activity frequently occurs due to mutations at, or amplifications of, upstream growth factor receptors (e.g., human epidermal growth factor receptor-2, HER2) as well as kinases (e.g., PI3K) and phosphatases (e.g., PTEN) critical in the regulation of cell growth. More recently, it has been shown that certain rapalogs may enhance the effectiveness of hormonal-based therapies for breast cancer patients who have become resistant to endocrine therapy. The combined treatment of certain rapalogs (e.g., everolimus) and aromatase inhibitors (e.g., exemestane) has been approved by the United States Food and Drug Administration (US FDA) and other drug regulatory agencies to treat estrogen receptor positive (ER+) breast cancer patients who have become resistant to hormonal-based therapies and have progressed. This review will summarize recent basic and clinical research in the area and evaluate potential novel therapeutic approaches.

Pictilisib for oestrogen receptor-positive, aromatase inhibitor-resistant, advanced or metastatic breast cancer (FERGI): a randomised, double-blind, placebo-controlled, phase 2 trial

BACKGROUND

Inhibition of phosphatidylinositol 3-kinase (PI3K) is a promising approach to overcome resistance to endocrine therapy in breast cancer. Pictilisib is an oral inhibitor of multiple PI3K isoforms. The aim of this study is to establish if addition of pictilisib to fulvestrant can improve progression-free survival in oestrogen receptor-positive, endocrine-resistant breast cancer.

METHODS

In this two-part, randomised, double-blind, placebo-controlled, phase 2 study, we recruited postmenopausal women aged 18 years or older with oestrogen receptor-positive, HER2-negative breast cancer resistant to treatment with an aromatase inhibitor in the adjuvant or metastatic setting, from 123 medical centres across 21 countries. Part 1 included patients with or without PIK3CA mutations, whereas part 2 included only patients with PIK3CA mutations. Patients were randomly allocated (1:1 in part 1 and 2:1 in part 2) via a computer-generated hierarchical randomisation algorithm to daily oral pictilisib (340 mg in part 1 and 260 mg in part 2) or placebo starting on day 15 of cycle 1, plus intramuscular fulvestrant 500 mg on day 1 and day 15 of cycle 1 and day 1 of subsequent cycles in both groups. In part 1, we stratified patients by presence or absence of PIK3CA mutation, primary or secondary aromatase inhibitor resistance, and measurable or non-measurable disease. In part 2, we stratified patients by previous aromatase inhibitor treatment for advanced or metastatic disease or relapse during or within 6 months of an aromatase inhibitor treatment in the adjuvant setting and measurable or non-measurable disease. All patients and those administering treatment and assessing outcomes were masked to treatment assignment. The primary endpoint was progression-free survival in the intention-to-treat population for both parts 1 and 2 and also separately in patients with PIK3CA-mutated tumours in part 1. Tumour assessment (physical examination and imaging scans) was investigator-assessed and done at screening and after 8 weeks, 16 weeks, 24 weeks, and 32 weeks of treatment from day 1 of cycle 1 and every 12 weeks thereafter. We assessed safety in as-treated patients who received at least one dose of study medication. This trial is registered with ClinicalTrials.gov, number NCT01437566.

FINDINGS

In part 1, between Sept 27, 2011, and Jan 11, 2013, we randomly allocated 168 patients to the pictilisib (89 [53%]) or placebo (79 [47%]) group. In part 2, between March 18, 2013, and Jan 2, 2014, we randomly allocated 61 patients to the pictilisib (41 [67%]) or placebo (20 [33%]) group. In part 1, we found no difference in median progression-free survival between the pictilisib (6·6 months [95% CI 3·9-9·8]) and placebo (5·1 months [3·6-7·3]) group (hazard ratio [HR] 0·74 [95% CI 0·52-1·06]; p=0·096). We also found no difference when patients were analysed according to presence (pictilisib 6·5 months [95% CI 3·7-9·8] vs placebo 5·1 months [2·6-10·4]; HR 0·73 [95% CI 0·42-1·28]; p=0·268) or absence (5·8 months [3·6-11·1] vs 3·6 months [2·8-7·3]; HR 0·72 [0·42-1·23]; p=0·23) of PIK3CA mutation. In part 2, we also found no difference in progression-free survival between groups (5·4 months [95% CI 3·8-8·3] vs 10·0 months [3·6-13·0]; HR 1·07 [95% CI 0·53-2·18]; p=0·84). In part 1, grade 3 or worse adverse events occurred in 54 (61%) of 89 patients in the pictilisib group and 22 (28%) of 79 in the placebo group. 19 serious adverse events related to pictilisib treatment were reported in 14 (16%) of 89 patients. Only one (1%) of 79 patients reported treatment-related serious adverse events in the placebo group. In part 2, grade 3 or worse adverse events occurred in 15 (36%) of 42 patients in the pictilisib group and seven (37%) of 19 patients in the placebo group. Four serious adverse events related to pictilisib treatment were reported in two (5%) of 42 patients. One treatment-related serious adverse event occurred in one (5%) of 19 patients in the placebo group.

INTERPRETATION

Although addition of pictilisib to fulvestrant did not significantly improve progression-free survival, dosing of pictilisib was limited by toxicity, potentially limiting its efficacy. For future assessment of PI3K inhibition as an approach to overcome resistance to hormonal therapy, inhibitors with greater selectivity than that of pictilisib might be needed to improve tolerability and potentially increase efficacy. No further investigation of pictilisib in this setting is ongoing.

FUNDING

F Hoffmann-La Roche.

Recent developments and translational aspects in targeted therapy for metastatic breast cancer

Biologically distinct subtypes of metastatic breast cancer (MBC) have been defined by multiple efforts in recent years, showing broad heterogeneity at the molecular level of disease. Throughout this endeavour, oncogenic drivers within MBC were identified as potential therapeutic targets. With recent results from clinical trials targeting these well-known cancer-promoting pathways, this review is trying to elucidate as well as summarise current new therapeutic aspects in MBC and shed light on translational aspects within this entity.

Analysis of PI3K/mTOR Pathway Biomarkers and Their Prognostic Value in Women with Hormone Receptor-Positive, HER2-Negative Early Breast Cancer

BACKGROUND: The PI3K/AKT/mTOR pathway alterations have been shown to play significant roles in the development, progression, and metastatic spread of breast cancer. Furthermore, they have been implicated in the process of drug resistance, especially endocrinal therapies. In this study, we aimed to define the correlation between the PI3K mutations and the expression of the phosphorylated forms of different downstream molecules in women with estrogen receptor (ER)–positive, human epidermal growth factor receptor 2–negative (luminal) early breast cancer treated at Cairo university hospitals. METHODS: Next-generation sequencing was used to detect mutations in the PIK3CA hotspots (in exons 9 and 20). Immunohistochemistry was performed on tissue microarray blocks prepared from samples of 35 Egyptian luminal breast cancer patients in the pathology department of Centre Léon Bérard (CLB). The intensity and the percentage of stained tumor cells were integrated to define high versus low biomarker expression. The cytoplasmic and nuclear stainings were graded separately. Patients were followed for a median of 4.7 years (2.1 to 6.9 years). Correlation was done between PI3K mutations and the immunohistochemistry expression of pAKT, LKB1, p4EBP1, and pS6 ribosomal protein (pS6RP) with the clinicopathologic features and disease free survival (DFS) of the patients. RESULTS: Median age at diagnosis was 51.3 years (range, 25 to 82 years). Tumors were larger than 20 mm in 79.2% of the cases, whereas 57.9% had axillary lymph node deposits. Only 12.3% of the patients had SBR grade I tumors, 50.8% had grade II, and 36.8% had grade III. ERs were negative in 6 patients (17%) after pathology review. Thirty-two cases were assessable for LKB1 and pAKT, 33 for p4EBP1 and pS6RP, and 24 for PI3K mutations. Nuclear LKB1, cytoplasmic LKB1, nuclear pAKT, cytoplasmic pAKT, nuclear p4EBP1, and cytoplasmic pS6RP expression was high in 65.6%, 62.5%, 62.5%, 68.8%, 42.4%, and 57.6%, respectively. PIK3CA mutations were found in 7 patients (29.2%). PI3K mutations were correlated with nuclear localization of pAKT (i.e., decreased cytoplasmic pAKT, P = .04; and increased nuclear pAKT, P = .10). There was a tendency toward an inverse correlation between PI3K mutations and the expression of pS6RP (P = .10) and p4EBP1 (P = .19). Nuclear LKB1 expression was a marker of good prognosis. It was associated with smaller tumors (P = .05), more ER (P = .08) and progesteron receptor (PgR) positivity (P = .002). In the Kaplan Meier (KM) model, patients with high nuclear LKB1 had longer DFS (hazard ratio = 0.36; 95% confidence interval, 0.15-1.10; P = .08). Nuclear pAKT high expression also carried a tendency toward longer DFS (hazard ratio = 0.51; 95% confidence interval, 0.11-1.16; P = .13). The expression of p4EBP1, pS6RP, and the PI3K mutational status did not show any prognostic significance in our cohort. CONCLUSION: Among the studied biomarkers, only nuclear expression of LKB1 and pAKT tended to predict better survival in breast cancer patients. PI3K mutation was correlated with the expression of nuclear pAKT but not pS6RP or p4EBP1.

Clinical utility of letrozole in the treatment of breast cancer: a Chinese perspective

The incidence rate of breast cancers in People’s Republic of China has increased in the last decade, and many cases are responsive to hormone therapies. The third-generation aromatase inhibitor letrozole inhibits estrogen production, and is more efficacious than the estrogen receptor inhibitor tamoxifen. In recent years, letrozole has been widely used to treat postmenopausal breast cancers in People’s Republic of China. Also, metastatic, premenopausal, and male breast cancers have been effectively treated by a combination of letrozole with cytotoxic, radiation, or other therapies. In this review, we provide a perspective and summary of recent advances in the use of letrozole for breast cancer in Chinese patients.

Neoadjuvant Model for Testing Emerging Targeted Therapies in Breast Cancer

Neoadjuvant trials provide endpoints, such as pathological complete response (pCR) to treatment, that will potentially translate into meaningful improvements in overall survival and disease-free survival. Neoadjuvant trials need smaller sample sizes and are less expensive, and the endpoint of pCR is achieved in months, rather than years. For these reasons, the neoadjuvant setting is ideal for testing emerging targeted therapies in early breast cancer. Recently the US Food and Drug Administration has released a draft Guidance to Industry, outlining a pathway to accelerated approval for neoadjuvant breast cancer therapies using pCR. The association between pCR and outcome is clear for chemotherapy in triple-negative breast cancer and for HER2-targeted agents in HER2-positive disease, but might not hold true for other tumor subtypes such as luminal cancers. Since pCR is rarely achieved with either chemotherapy or endocrine therapy in hormone-receptor-positive breast cancer, in this setting we need to identify different intermediate endpoints, which might be translational endpoints within "window-of-opportunity," "residual disease," and "genome forward" trials. Prospective validation of effective noninvasive techniques for monitoring of residual disease burden could enhance the ability to identify promising targeted therapies in the neoadjuvant setting.

Early Surrogate Markers of Treatment Activity: Where Are We Now?

The assessment of new therapies in the adjuvant setting in early breast cancer requires large numbers of patients and many years of follow-up for results to be presented. Therefore, the neoadjuvant study setting, which allows for early prediction of treatment response in smaller patient sets, has become increasingly popular. Ki67 is the most commonly used and extensively studied intermediate biomarker of treatment activity and residual risk in neoadjuvant trials on endocrine therapy, new biological therapies, and chemotherapy. It is increasingly being used as a primary endpoint for new therapies particularly those added to endocrine therapy. The PeriOperative Endocrine Therapy for Individualizing Care (POETIC) trial, including more than 4000 postmenopausal, estrogen receptor (ER)-positive patients randomly assigned to receive 2 weeks of presurgical treatment with an aromatase inhibitor or no further treatment, is the largest window-of-opportunity trial conducted and is assessing the clinical utility of on-treatment Ki67 as a predictor of long-term outcome. For generalizability, Ki67 measurements in the POETIC and other trials need to use standard methodology. The International Working Group on Ki67 in Breast Cancer is conducting a series of studies to bring this to reality.

JAK2 inhibition sensitizes resistant EGFR-mutant lung adenocarcinoma to tyrosine kinase inhibitors

Lung adenocarcinomas with mutant epidermal growth factor receptor (EGFR) respond to EGFR-targeted tyrosine kinase inhibitors (TKIs), but resistance invariably occurs. We found that the Janus kinase (JAK)/signal transduction and activator of transcription 3 (STAT3) signaling pathway was aberrantly increased in TKI-resistant EGFR-mutant non-small cell lung cancer (NSCLC) cells. JAK2 inhibition restored sensitivity to the EGFR inhibitor erlotinib in TKI-resistant cell lines and xenograft models of EGFR-mutant TKI-resistant lung cancer. JAK2 inhibition uncoupled EGFR from its negative regulator, suppressor of cytokine signaling 5 (SOCS5), consequently increasing EGFR abundance and restoring the tumor cells' dependence on EGFR signaling. Furthermore, JAK2 inhibition led to heterodimerization of mutant and wild-type EGFR subunits, the activity of which was then blocked by TKIs. Our results reveal a mechanism whereby JAK2 inhibition overcomes acquired resistance to EGFR inhibitors and support the use of combination therapy with JAK and EGFR inhibitors for the treatment of EGFR-dependent NSCLC.

Optimizing the use of neoadjuvant endocrine therapy

Nowadays, neoadjuvant endocrine therapy is a clinically acceptable (and sometimes preferred) strategy in patients with operable estrogen receptor-positive (ER+) breast cancer. Despite the overall effectiveness of endocrine therapy in breast cancer in all settings, de novo (primary) and acquired (secondary) endocrine therapy resistance remains a major clinical problem. Neoadjuvant endocrine therapy trials for breast cancer are not only a great opportunity to determine which ER+ breast cancers can be treated without chemotherapy, but also a great strategy to develop insights into the biologic basis for the efficacy of estrogen-receptor-targeting agents, alone or in combination, in an effort to counteract resistance to endocrine therapy and discover actionable molecular targets that can be the focus of future drug discovery efforts and/or translational/clinical investigation in ER+ breast cancers.

Phase II Randomized Preoperative Window-of-Opportunity Study of the PI3K Inhibitor Pictilisib Plus Anastrozole Compared With Anastrozole Alone in Patients With Estrogen Receptor-Positive Breast Cancer

PURPOSE

Preclinical data support a key role for the PI3K pathway in estrogen receptor-positive breast cancer and suggest that combining PI3K inhibitors with endocrine therapy may overcome resistance. This preoperative window study assessed whether adding the PI3K inhibitor pictilisib (GDC-0941) can increase the antitumor effects of anastrozole in primary breast cancer and aimed to identify the most appropriate patient population for combination therapy.

PATIENTS AND METHODS

In this randomized, open-label phase II trial, postmenopausal women with newly diagnosed operable estrogen receptor-positive, human epidermal growth factor receptor 2 (HER2)-negative breast cancers were recruited. Participants were randomly allocated (2:1, favoring the combination) to 2 weeks of preoperative treatment with anastrozole 1 mg once per day (n = 26) or the combination of anastrozole 1 mg with pictilisib 260 mg once per day (n = 49). The primary end point was inhibition of tumor cell proliferation as measured by change in Ki-67 protein expression between tumor samples taken before and at the end of treatment.

RESULTS

There was significantly greater geometric mean Ki-67 suppression of 83.8% (one-sided 95% CI, ≥ 79.0%) for the combination and 66.0% (95% CI, ≤ 75.4%) for anastrozole (geometric mean ratio [combination:anastrozole], 0.48; 95% CI, ≤ 0.72; P = .004). PIK3CA mutations were not predictive of response to pictilisib, but there was significant interaction between response to treatment and molecular subtype (P = .03); for patients with luminal B tumors, the combination:anastrozole geometric mean ratio of Ki-67 suppression was 0.37 (95% CI, ≤ 0.67; P = .008), whereas no significant Ki-67 response was observed for pictilisib in luminal A tumors (1.01; P = .98). Multivariable analysis confirmed Ki-67 response to the combination treatment of patients with luminal B tumors irrespective of progesterone receptor status or baseline Ki-67 expression.

CONCLUSION

Adding pictilisib to anastrozole significantly increases suppression of tumor cell proliferation in luminal B primary breast cancer.

Endocrine therapy in post-menopausal women with metastatic breast cancer: From literature and guidelines to clinical practice

Current international guidelines recommend endocrine therapy as the initial treatment of choice in hormone receptor positive advanced breast cancer. Endocrine therapy has been a mainstay of hormone responsive breast cancer treatment for more than a century. To date it is based on different approaches,such as blocking the estrogen receptor through selective receptor estrogen modulators, depleting extragonadal peripheral estrogen synthesis by aromatase inhibitors or inducing estrogen receptor degradation using selective down-regulators. Despite estrogen and/or progesterone receptor positive status, up to a quarter of patients could be either primarily resistant to hormone therapies or will develop hormone resistance during the course of their disease. Different mechanisms, either intrinsic or acquired, could be implicated in endocrine resistance. In the present work available endocrine therapies and their appropriate sequences have been reviewed, and the most promising strategies to overcome endocrine resistance have been highlighted.

Molecular Testing and the Pathologist's Role in Clinical Trials of Breast Cancer

Molecular characterization of breast cancer is pivotal for identifying new molecular targets and determining the appropriate treatment choices. Advances in molecular profiling technology have given greater insight into this heterogeneous disease, over and above hormone receptor and human epidermal growth factor receptor 2 status. Agents targeting recently characterized molecular biomarkers are under clinical development; the success of these targeted agents is likely to depend on identifying the patient population most likely to benefit. Therefore, clinical trials of breast cancer often require prescreening for, or stratification by, relevant molecular markers or exploratory analyses of biomarkers that can predict or monitor the response to treatment. Consequently, the role of the pathologist has become increasingly important. The key considerations for pathologists include tissue availability, ownership of archival tissue, type of diagnostic/biomarker test required, method of sample processing, concordance between different tests and testing centers, and tumor heterogeneity. In the present review, we explore how pathology is used in current clinical trials of breast cancer and describe the various technologies available for molecular testing. Furthermore, the factors required for the successful application of pathology in clinical trials of breast cancer and the issues that can arise and how these can be circumvented are discussed.

Neoadjuvant endocrine therapy in breast cancer: current role and future perspectives

Luminal breast cancer, as defined by oestrogen and/or progesterone expression by immunohistochemistry, accounts for up to 75% of all breast cancers. In this population, endocrine therapy is likely to account for most of the gains obtained with the administration of adjuvant systemic treatment. The role of adjuvant chemotherapy in these patients remains debatable since it is known that only a small fraction of patients will derive meaningful benefit from this treatment whilst the majority will be exposed to significant and unnecessary chemotherapy-related toxicities, in particular the elderly and frail. Therefore, neoadjuvant endocrine therapy (NET) becomes an attractive option for selected patients with hormonal-receptor positive locally advanced breast cancer. In this review, we discuss the current role of NET and future perspectives in the field.

Resistance to Targeted Therapies in Breast Cancer

Seventy five percent of all breast cancer (BC) patients express estrogen receptor (ER) but a quarter to half of patients with ER positive BC relapse on ET (endocrine therapy), tamoxifen, aromatase inhibitors (AIs), surgical castration, amongst other treatment strategies. ER positive BC at relapse loses ER expression in 20 % of cases and reduces quantitative ER expression most of the time. ER is not the only survival pathway driving ER positive BC and escape pathways intrinsic or acquired are activated during ET. This overview gives an account of ligand-independent ER activation, namely by receptor networks cross talk, and by the various genomic factors and mechanisms leading to ET response failure. Also the mechanisms of Her1 and Her2 inhibition resistance are dealt within this overview, along with the therapeutic indications and limitations of tyrosine kinase inhibitors, PARP inhibitors, PI3K/AKT/mTOR inhibitors, RAS/RAF/MEK/ERK/MAPK inhibitors, and antiangiogenic drugs. In spite of the many advances in controlling the division of BC cells and the progression of BC tumors these still remain the main cause of death among women in age range of 20-50 years requiring even more efforts in new therapeutic approaches besides the drugs within the scope of the overview.

Potential role for mammalian target of rapamycin inhibitors as first-line therapy in hormone receptor-positive advanced breast cancer

Despite advances in cytotoxic chemotherapy and targeted therapies, 5-year survival rates remain low for patients with advanced breast cancer at diagnosis. This highlights the limited effectiveness of current treatment options. An improved understanding of cellular functions associated with the development and progression of breast cancer has resulted in the creation of a number of novel targeted molecular therapies. However, more work is needed to improve outcomes, particularly in the first-line recurrent or metastatic hormone receptor-positive breast cancer setting. The phosphatidylinositol 3-kinase/protein kinase B/mammalian target of rapamycin (mTOR) pathway is a major intracellular signaling pathway that is often upregulated in breast cancer, and overactivation of this pathway has been associated with primary or developed resistance to endocrine treatment. Clinical data from the Phase III Breast Cancer Trials of Oral Everolimus-2 (BOLERO-2) study of the mTOR inhibitor everolimus combined with exemestane in hormone receptor-positive advanced breast cancer were very promising, highlighting the potential role of mTOR inhibitors in combination with endocrine therapies as a first-line treatment option for these patients. It is hoped that the use of mTOR inhibitors combined with current standard-of-care endocrine therapies, such as aromatase inhibitors, in the first-line advanced breast cancer setting may result in greater antitumor effects and also delay or reverse treatment resistance.

Neoadjuvant endocrine treatment in early breast cancer: An overlooked alternative?

During the last decade neoadjuvant endocrine therapy (NET) has moved from being reserved for elderly and frail non-chemotherapy candidates to a primary systemic modality in selected patients with hormone sensitive breast cancer. Neoadjuvant hormonal treatment in patients with hormone receptor positive, HER-2 negative early breast cancer is proven to be an effective and safe option; it is associated with a higher rate of breast conserving surgery (BCS), may reduce the need for adjuvant chemotherapy and enables a delay of surgery for medical or practical reasons. Clinical responses range from 13% to 100% with at least 3 months of NET. Methods of assessing response should include MRI of the breast, particularly in lobular tumours. In studies comparing tamoxifen with aromatase inhibitors (AI), AI proved to be superior in terms of tumour response and rates of BCS. Change in Ki67 is accepted as a validated endpoint for comparing endocrine neoadjuvant agents. Levels of Ki67 during treatment are more closely related to long-term prognosis than pretreatment Ki67. Neoadjuvant endocrine therapy provides a unique opportunity for studies of endocrine responsiveness and the development of new experimental drugs combined with systemic hormonal treatment.

Treatment strategies for advanced hormone receptor-positive and human epidermal growth factor 2-negative breast cancer: the role of treatment order

Although survival rates among patients with breast cancer have improved in recent years, those diagnosed with advanced disease with distant metastasis face a 5-year survival rate of less than 25%, making the management of these patients an area still in significant need of continued research. Selecting the optimal treatment order from among the variety of currently available therapy options presents a relevant challenge for medical oncologists. With the understanding that the majority of patients with breast cancer and those who succumb to this disease have HR-positive disease, this review will focus on treatment options and treatment order in patients with HR-positive advanced breast cancer. While endocrine therapy is considered the preferred treatment for first-line therapy in HR-positive/HER2-negative breast cancer, selection of the specific agent depends on the menopausal status of the patient. Palbociclib, a cyclin-dependent kinase (CDK) 4/6 inhibitor, is also recommended as first-line treatment in patients with ER-positive/HER2-negative disease. In patients with endocrine therapy-resistant disease, specific strategies include sequencing of other antiestrogen receptor agents, or agents that target other molecular pathways. Future treatment strategies for patients with primary or secondary resistance to endocrine therapy for advanced disease are discussed. These strategies include first-line therapy with high-dose fulvestrant or everolimus (in combination with exemestane or letrozole or with other endocrine therapies), use of the PI3K inhibitors (e.g., buparlisib, alpelisib, pictilisib, taselisib), entinostat, CDK 4/6 inhibitors (e.g., palbociclib, ribociclib, abemaciclib), and novel selective estrogen receptor degradation agents that may enhance the targeting of acquired mutations in the ESR1 gene.

mTORC1 directly phosphorylates and activates ERα upon estrogen stimulation

Breast cancer is the leading cause of cancer-related deaths among women. Approximately 75% of breast cancers are estrogen receptor α (ERα) positive, underscoring the dependence of cancer cells on estrogen for growth and survival. Patients treated with endocrine therapy often develop resistance, either de novo or acquired, which in some cases is caused by aberrations within the growth factor signaling pathways. The mechanistic target of rapamycin complex 1 (mTORC1) has emerged as a critical node in estrogenic signaling. We have previously shown that mTORC1 can phosphorylate and activate ERα on S167 via its effector the 40S ribosomal S6 kinase 1 (S6K1). Presently, we have uncovered a direct link between mTORC1 and ERα. We found that ERα binds to regulatory-associated protein of mTOR (Raptor) and causes it to translocate to the nucleus upon estrogen stimulation. Additionally, we identified mTOR as the kinase that phosphorylates ERα on S104/106 and activates transcription of ER target genes. Our findings show a direct link between mTORC1 and ERα, which further implicates mTORC1 signaling in the pathogenesis of ER-positive breast cancer and provides rationale for FDA-approved use of mTORC1 inhibitors in combination with endocrine agents for treatment of this disease.

Correlative Analysis of Genetic Alterations and Everolimus Benefit in Hormone Receptor-Positive, Human Epidermal Growth Factor Receptor 2-Negative Advanced Breast Cancer: Results From BOLERO-2

PURPOSE

To explore the genetic landscape of tumors from patients enrolled on the BOLERO-2 trial to identify potential correlations between genetic alterations and efficacy of everolimus treatment. The BOLERO-2 trial has previously demonstrated that the addition of everolimus to exemestane prolonged progression-free survival by more than twofold in patients with hormone receptor-positive, human epidermal growth factor receptor 2-negative, advanced breast cancer previously treated with nonsteroidal aromatase inhibitors.

PATIENTS AND METHODS

Next-generation sequencing was used to analyze genetic status of cancer-related genes in 302 archival tumor specimens from patients representative of the BOLERO-2 study population. Correlations between the most common somatic alterations and degree of chromosomal instability, and treatment effect of everolimus were investigated.

RESULTS

Progression-free survival benefit with everolimus was maintained regardless of alteration status of PIK3CA, FGFR1, and CCND1 or the pathways of which they are components. However, quantitative differences in everolimus benefit were observed between patient subgroups defined by the exon-specific mutations in PIK3CA (exon 20 v 9) or by different degrees of chromosomal instability in the tumor tissues.

CONCLUSION

The data from this exploratory analysis suggest that the efficacy of everolimus was largely independent of the most commonly altered genes or pathways in hormone receptor-positive, human epidermal growth factor receptor 2-negative breast cancer. The potential impact of chromosomal instabilities and low-frequency genetic alterations on everolimus efficacy warrants further investigation.

Anticancer effect of rapamycin on MCF-7 via downregulation of VEGF expression

The importance of mTOR signaling in tumor biology is widely accepted and a number of agents that selectively target mTOR are being developed in cancer therapy. On the other hand, it has been demonstrated that mTOR can act as an angiogenic agent. Thus, we hypothesized that the mTOR inhibitor-induced anticancer effect is affected by expression of a key angiogenic factor, vascular endothelial growth factor (VEGF) and investigated the anticancer effect underlying mTOR using an in vitro assay. The mTOR inhibitor rapamycin dose-dependently reduced the cell viability of the breast cancer cell line, MCF-7, but did not reduce the cell viability of the colon cancer cell line, HT-29. Rapamycin reduced the VEGF expression in the culture medium of MCF-7, while rapamycin did not contribute VEGF expression in the culture medium of HT-29. VEGF stimulated cell viability and VEGF inhibition reduced cell viability of MCF-7, and rapamycin dose-dependently restored the cell viability of MCF-7 reduced by rapamycin. These findings suggest that mTOR acts as a direct anticancer agent and that the mTOR-inhibitor-induced anticancer effect involved the reduced expression of VEGF in MCF-7. Our results imply that mTOR regulates the expression of VEGF and is involved in breast cancer progression.

Emerging strategies for targeting PI3K in gynecologic cancer

Ovarian, endometrial and cervical cancers are the most prevalent gynecologic cancers in the United States and account for significant mortality. Translational research into these cancers has highlighted the distinctive molecular and genomic profiles of these cancers finding that, even within a disease site, the landscapes and drivers of neoplasia are distinctive. Despite this molecular diversity, activation of the phosphatidylinositol-3-kinase (PI3K) pathway appears to be conserved in subsets of these tumors, suggesting that strategies that antagonize mediators in this signaling cascade could offer anti-tumor efficacy. Extensive pre-clinical and clinical data have demonstrated that single agent targeted therapies lead to modest single agent activity of generally limited duration, even in the setting of innate PI3K pathway activation via mutation or amplification. These findings in the laboratory and clinic have prompted investigations into resistance pathways following PI3K pathway inhibition in order to understand escape pathways and restore tumor cell sensitivity. A next generation of clinical trial investigations will focus on novel combinations in order to define how these important therapeutics can be used in the clinic. This review will present preclinical data that supports the role of the PI3K pathway in ovarian, endometrial and cervical cancers, in addition to discussing the reported clinical trial experience with PI3K pathway inhibition. A specific focus will be on the rationale behind ongoing clinical trials utilizing novel agents in concert with PI3K pathway inhibitors to reverse resistance in populations with and without gain of function alterations in this oncogenic signaling cascade.

Endocrine therapy resistance in breast cancer: current status, possible mechanisms and overcoming strategies

Endocrine therapy has become one of most effective forms of targeted adjuvant therapy for hormone-sensitive breast cancer and may be given after surgery or radiotherapy, and also prior, or subsequent to chemotherapy. Current commonly used drugs for adjuvant endocrine therapy can be divided into following three classes: selective estrogen receptor modulators, aromatase inhibitors and selective estrogen receptor downregulators. Tumor cells can develop resistance to endocrine therapy, a major obstacle limiting the success of breast cancer treatment. The complicated crosstalk, both genomic and nongenomic, between estrogen receptors and growth factors was considered to be a crucial factor contributing to endocrine resistance. However, resistance to this therapy is thought to be a progressive, step-wise process, and the underlying mechanism remains unclear. In this review, we summarize the possible biological and molecular mechanisms that underlie endocrine resistance, and discuss some novel strategies to overcoming these issues.

Neoadjuvant endocrine therapy: Patient selection, treatment duration and surrogate endpoints

Neoadjuvant endocrine treatment has become of increasing interest for downstaging primary ER+ breast cancers as it has become clear that the pathologic complete response rate of luminal tumours to chemotherapy is much lower than that of non-luminal and differs little from that to endocrine therapy. There is much more experience in postmenopausal than premenopausal women. Aromatase inhibitors are generally the agent of choice. Responses are lower in those with the low levels of ER. While duration of endocrine treatment in clinical trials has usually been standardized at around three to four months it is clear that volume reductions continue to occur beyond that time in a large proportion of cases and routine clinical practice is often to treat to maximum response. This relatively slow emergence of downstaging relates to the absence of any increase in apoptosis with endocrine therapy and dependence of responses on the antiproliferative effects of oestrogen withdrawal: apoptosis occurs but at a slightly lower rate such that cell loss is attritional. The dependence of responses on the reduced proliferation underpins the value of Ki67 as an intermediate end-point for treatment benefit with multiple studies having found that relative effects on proliferation by different drugs in neoadjuvant trials match their relative impact on recurrence. While change in Ki67 is now accepted as a validated endpoint for comparing endocrine agents in the neoadjuvant scenario, on-treatment levels of Ki67 are related to long-term prognosis more closely than pretreatment Ki67. The Preoperative Endocrine Prognostic Index (PEPI) that combines residual Ki67 score with measures of on-treatment ER and other clinicopathologic factors has also found application in clinical trials. The potential to make longitudinal assessments of both clinical and biomarker responses has encouraged the development of novel clinical trial designs for assessing the impact of agents that aim to enhance response beyond that of endocrine agents alone. Such strategies include the early measurement of residual Ki67 levels after challenge with an endocrine agent alone and evaluation of the impact of the added agent on Ki67 or other agent-specific end-points.

Everolimus use and associated factors among post-menopausal women with hormonal receptor positive/human epidermal growth factor receptor 2 negative metastatic breast cancer

BACKGROUND

Everolimus has been shown to be an effective HR+/HER2- mBC treatment in both clinical trials and real-world practice. The current study aims at understanding factors associated with everolimus use and how it is used in the real world.

METHODS

A retrospective chart review was conducted among postmenopausal HR+/HER2- mBC women who received everolimus, endocrine therapy (ET), or chemotherapy (CT) for mBC between 1 July 2012 and 15 April 2013 after an NSAI failure. Factors associated with everolimus use versus ET or CT were identified using multivariable logistic regressions. Reasons for prescribing everolimus and everolimus treatment patterns were described.

RESULTS

Liver metastasis and high tumor volume were associated with a higher likelihood of everolimus use versus ET (OR = 1.67, OR = 1.62) but a lower likelihood of everolimus use versus CT (OR = 0.43, OR = 0.30). Medicare-only insurance (OR = 0.30) as well as ECOG ≥2 (OR = 3.72) and prior CT in mBC (OR = 2.76) were associated with a lower and higher likelihood of everolimus use versus CT, respectively. The top reason for prescribing everolimus was efficacy (69-85%). About 15% and 29% of everolimus users in second line and third line or above received prior CT for mBC. Exemestane was the most common concomitant therapy with everolimus (56-87%). The majority of patients initiated everolimus at the labeled dose of 10 mg daily (>80%) and maintained this dose (>80%).

CONCLUSIONS

In the real world, everolimus was used in more severe patients than ET but less severe patients than CT based on visceral metastasis, tumor volume, and performance status. The top reason for prescribing everolimus was efficacy. A large proportion of patients received first or second line CT before everolimus initiation. The majority of patients used everolimus according to the labeled combination and dose. Future studies are needed to determine optimal sequencing of everolimus, ET, and CT for HR+/HER2- mBC.

Precise Classification of Cervical Carcinomas Combined with Somatic Mutation Profiling Contributes to Predicting Disease Outcome

Introduction

Squamous cell carcinoma (SCC), adenocarcinoma (AC), and adenosquamous carcinoma (ASC) are the most common histological subtypes of cervical cancer. Differences in the somatic mutation profiles of these subtypes have been suggested. We investigated the prevalence of somatic hot-spot mutations in three well-defined cohorts of SCC, AC, and ASC and determined the additional value of mutation profiling in predicting disease outcome relative to well-established prognostic parameters.

Materials and Methods

Clinicopathological data were collected for 301 cervical tumors classified as SCC (n=166), AC (n=55), or ASC (n=80). Mass spectrometry was used to analyze 171 somatic hot-spot mutations in 13 relevant genes.

Results

In 103 (34%) tumors, 123 mutations were detected (36% in SCC, 38% in AC, and 28% in ASC), mostly in PIK3CA (20%) and KRAS (7%). PIK3CA mutations occurred more frequently in SCC than AC (25% vs. 11%, P=0.025), whereas KRAS mutations occurred more frequently in AC than SCC (24% vs. 3%, P<0.001) and ASC (24% vs. 3%, P<0.001). A positive mutation status correlated with worse disease-free survival (HR 1.57, P=0.043). In multivariate analysis, tumor diameter, parametrial infiltration, and lymph node metastasis, but not the presence of a somatic mutation, were independent predictors of survival.

Conclusion

Potentially targetable somatic mutations occurred in 34% of cervical tumors with different distributions among histological subtypes. Precise classification of cervical carcinomas in combination with mutation profiling is valuable for predicting disease outcome and may guide the development and selection of tumor-specific treatment approaches.

Targeted Therapies in Breast Cancer: Implications for Advanced Oncology Practice

The systemic therapeutic management of breast cancer has undergone significant transformation in the past decade. Without targeted therapies, conventional treatment with cytotoxic agents has reached the limit of its potential in terms of patient survival for most types of cancer. Enhanced understanding of the pathogenesis of tumor cell growth and metastasis has led to the identification of signaling growth pathways as targets for these directed therapies. Novel therapies targeted to HER2/neu, epidermal growth factor receptor (EGFR), vascular endothelial growth factor (VEGF), poly(ADP ribose) polymerase (PARP), mammalian target of rapamycin (mTOR), histone deacetylase (HDAC), the heat shock protein, and cyclin-dependent kinase (CDK) inhibitors have been developed and have demonstrated some efficacy in breast cancer. Recognition and management of the toxicities associated with targeted therapies is imperative. This review will describe the clinical development and utilization of targeted therapies currently in use or in clinical trials, with a focus on considerations for the oncology advanced practitioner.

Targeted therapies for ER+/HER2- metastatic breast cancer

The majority of breast cancers present with estrogen receptor (ER)-positive and human epidermal growth factor receptor (HER2)-negative features and might benefit from endocrine therapy. Although endocrine therapy has notably evolved during the last decades, the invariable appearance of endocrine resistance, either primary or secondary, remains an important issue in this type of tumor. The improvement of our understanding of the cancer genome has identified some promising targets that might be responsible or linked to endocrine resistance, including alterations affecting main signaling pathways like PI3K/Akt/mTOR and CCND1/CDK4-6 as well as the identification of new ESR1 somatic mutations, leading to an array of new targeted therapies that might circumvent or prevent endocrine resistance. In this review, we have summarized the main targeted therapies that are currently being tested in ER+ breast cancer, the rationale behind them, and the new agents and combinational treatments to come.

S6 kinase signaling: tamoxifen response and prognostic indication in two breast cancer cohorts

Detection of signals in the mammalian target of rapamycin (mTOR) and the estrogen receptor (ER) pathways may be a future clinical tool for the prediction of adjuvant treatment response in primary breast cancer. Using immunohistological staining, we investigated the value of the mTOR targets p70-S6 kinase (S6K) 1 and 2 as biomarkers for tamoxifen benefit in two independent clinical trials comparing adjuvant tamoxifen with no tamoxifen or 5 years versus 2 years of tamoxifen treatment. In addition, the prognostic value of the S6Ks was evaluated. We found that S6K1 correlated with proliferation, HER2 status, and cytoplasmic AKT activity, whereas high protein expression levels of S6K2 and phosphorylated (p) S6K were more common in ER-positive, and low-proliferative tumors with pAKT-s473 localized to the nucelus. Nuclear accumulation of S6K1 was indicative of a reduced tamoxifen effect (hazard ratio (HR): 1.07, 95% CI: 0.53-2.81, P=0.84), compared with a significant benefit from tamoxifen treatment in patients without tumor S6K1 nuclear accumulation (HR: 0.42, 95% CI: 0.29-0.62, P<0.00001). Also S6K1 and S6K2 activation, indicated by pS6K-t389 expression, was associated with low benefit from tamoxifen (HR: 0.97, 95% CI: 0.50-1.87, P=0.92). In addition, high protein expression of S6K1, independent of localization, predicted worse prognosis in a multivariate analysis, P=0.00041 (cytoplasm), P=0.016 (nucleus). In conclusion, the mTOR-activated kinases S6K1 and S6K2 interfere with proliferation and response to tamoxifen. Monitoring their activity and intracellular localization may provide biomarkers for breast cancer treatment, allowing the identification of a group of patients less likely to benefit from tamoxifen and thus in need of an alternative or additional targeted treatment.

Multiple gene aberrations and breast cancer: lessons from super-responders

BACKGROUND

The presence of multiple molecular aberrations in patients with breast cancer may correlate with worse outcomes.

CASE PRESENTATIONS

We performed in-depth molecular analysis of patients with estrogen receptor-positive, HER2-negative, hormone therapy-refractory breast cancer, who achieved partial or complete responses when treated with anastrozole and everolimus. Tumors were analyzed using a targeted next generation sequencing (NGS) assay in a Clinical Laboratory Improvement Amendments laboratory. Genomic libraries were captured for 3,230 exons in 182 cancer-related genes plus 37 introns from 14 genes often rearranged in cancer and sequenced to high coverage. Patients received anastrozole (1 g PO daily) and everolimus (5 or 10 mg PO daily). Thirty-two patients with breast cancer were treated on study and 5 (16 %) achieved a partial or complete response. Primary breast tissue was available for NGS testing in three of the responders (partial response with progression free survival of 11 and 14 months, respectively; complete response with progression free survival of 9+ months). The following molecular aberrations were observed: PTEN loss by immunohistochemistry, CCDN1 and FGFR1 amplifications, and PRKDC re-arrangement (NGS) (patient #1); PIK3CA and PIK3R1 mutations, and CCDN1, FGFR1, MYC amplifications (patient #2); TP53 mutation, CCNE1, IRS2 and MCL1 amplifications (patient #3). Some (but not all) of these aberrations converge on the PI3K/AKT/mTOR pathway, perhaps accounting for response.

CONCLUSIONS

Patients with estrogen receptor-positive breast cancer can achieve significant responses on a combination of anastrozole and everolimus, even in the presence of multiple molecular aberrations. Further study of next generation sequencing-profiled tumors for convergence and resistance pathways is warranted.

Challenges in the management of advanced, ER-positive, HER2-negative breast cancer

Hormone-receptor-positive breast cancer accounts for the majority-up to 80%-of all breast cancers. The evolution of breast cancer from early stage to the metastatic setting leads to increased heterogeneity, the occurrence of new mutations, and the development of treatment resistance representing a great challenge for management decisions. Unfortunately, little data exist to offer guidance in this context, and a reliance on traditional clinical parameters remains when deciding on optimal treatment. In advanced-stage oestrogen receptor-positive (ER+) disease, ongoing issues include the choice between endocrine therapy and chemotherapy, the appropriate sequence of treatment agents, and the incorporation of biological agents, such as everolimus, into the treatment armamentarium. In metastatic disease, repeated biopsies can help to reassess the receptor or genetic mutational status; however, the evidence to support this approach is limited. In this Review, we examine the current evidence that can guide treatment decisions in patients with advanced-stage ER+ breast cancer, discuss how to tackle these therapeutic challenges and provide suggestions for the optimal management of this patient population.

Crosstalk with insulin and dependence on PI3K/Akt/mTOR rather than MAPK pathways in upregulation of basal growth following long-term oestrogen deprivation in three human breast cancer cell lines

BACKGROUND

MCF-7, T-47-D, ZR-75-1 human breast cancer cell lines are dependent on oestrogen for growth but can adapt to grow during long-term oestrogen deprivation. This serves as a model for identification of therapeutic targets in endocrine-resistant breast cancer.

METHODS

An overlooked complication of this model is that it involves more than non-addition of oestrogen, and inadequate attention has been given to separating molecular events associated with each of the culture manipulations.

RESULTS

Insulin and oestradiol were shown to protect MCF-7 cells against upregulation of basal growth, demonstrating a crosstalk in the growth adaptation process. Increased phosphorylation of p44/42MAPK and c-Raf reflected removal of insulin from the medium and proliferation of all three cell lines was inhibited to a lesser extent by PD98059 and U0126 following long-term oestrogen/insulin withdrawal, demonstrating a reduced dependence on the MAPK pathway. By contrast, long-term oestrogen/insulin deprivation did not alter levels of phosphorylated Akt and did not alter the dose-response of growth inhibition with LY294002 in any of the three cell lines. The IGF1R inhibitor picropodophyllin inhibited growth of all MCF-7 cells but only in the long-term oestrogen/insulin-deprived cells was this paralleled by reduction in phosphorylated p70S6K, a downstream target of mTOR. Long-term oestrogen/insulin-deprived MCF-7 cells had higher levels of phosphorylated p70S6K and developed increased sensitivity to growth inhibition by rapamycin.

CONCLUSIONS

The greater sensitivity to growth inhibition by rapamycin in all three cell lines following long-term oestrogen/insulin deprivation suggests rapamycin-based therapies might be more effective in breast cancers with acquired oestrogen resistance.

Antihormone induced compensatory signalling in breast cancer: an adverse event in the development of endocrine resistance

Using MCF7 breast cancer cells, it has been shown that antihormones promote expression/activity of oestrogen-repressed tyrosine kinases, notably EGFR, HER2 and Src. These inductive events confer responsiveness to targeted inhibitors (e.g., gefitinib, trastuzumab, saracatinib). We observed that these antihormone-induced phenomena are common to ER+HER2- and ER+HER2+ breast cancer models in vitro, where targeting of EGFR, HER2 or Src alongside antihormone improves antitumour response and delays/prevents endocrine resistance. Such targeted inhibitors also subvert acquired endocrine resistant cells which retain increased EGFR, HER2 and Src (e.g., TAMR and FASR models derived after 6-12 months of tamoxifen or Faslodex treatment). Thus, antihormone-induced tyrosine kinases comprise "compensatory signalling" crucial in limiting maximal initial antihormone response and subsequently driving acquired resistance in vitro. However, despite such convincing preclinical findings from our group and others, clinical trials examining equivalent antigrowth factor strategies have proved relatively disappointing. Our new studies deciphering underlying causes reveal that further antihormone-promoted events could be pivotal in vivo. Firstly, Faslodex induces HER3 and HER4 which sensitise ER+ cells to heregulin, a paracrine growth factor that overcomes endocrine response and diminishes antitumour effect of agents targeting EGFR, HER2 or Src alongside antihormone. Secondly, extended antihormone exposure (experienced by ER+ cells prior to adjuvant clinical relapse) can "reprogramme" the compensatory kinase profile in vitro, hindering candidate antigrowth factor targeting of endocrine resistance. Faslodex resistant cells maintained with this antihormone for 3 years in vitro lose EGFR/HER2 dependency, gaining alternative mitogenic/invasion kinases. Deciphering these previously unrecognised antihormone-induced events could provide superior treatments to control endocrine relapse in the clinic.

Targeted Therapies Overcoming Endocrine Resistance in Hormone Receptor-Positive Breast Cancer

Breast cancer is a heterogeneous disease with different molecular subtypes. Most tumours are hormone receptor positive (luminal subtype) with potential endocrine responsiveness. Endocrine therapy is commonly used in these patients. Disease progression caused by endocrine resistance represents a significant challenge in the treatment of breast cancer. To understand the mechanisms of resistance of long-term oestrogen-deprived breast cancer cells, it is important to focus on cross-talk between steroid receptor signalling and other growth factor receptors and intracellular pathways. (Pre-)clinical trials showed that co-targeting these pathways can restore endocrine sensitivity. The focus of the current review is on the intracellular PI3K/AKT/mTOR signalling pathway and cyclin-dependant kinases (CDKs) in oestrogen receptor (ER)-positive breast cancer. Study results clearly show that both inhibition of the PI3K/AKT/mTOR pathway and CDK4/6 are promising ways to improve the efficacy of endocrine treatment in ER-positive breast cancer patients with comparably few side effects. Further clinical trials are needed to identify the patient population who would benefit most from a dual inhibition.

Effect of targeted agents on the endocrine response of breast cancer in the neoadjuvant setting: a systematic review

Inhibition of aberrantly activated pathways cross-talking with hormone receptor (HR) improves response to endocrine therapy in patients with HR-positive advanced breast cancer. We performed a Pubmed database systematic review to ascertain the existence of a better clinical response when combining endocrine therapy with targeted agents in the neoadjuvant setting. Preclinical studies or trials evaluating toxicity were excluded.

We found nine phase II trials that fulfilled the research criteria. The endocrine agents used were third generation aromatase inhibitors (AIs), anastrozole, letrozole or exemestane. The investigated targeted agents were inhibitors of tyrosine kinase receptors such as gefitinib, imatinib or trastuzumab/lapatinib, inhibitors of mTOR, such as everolimus, inhibitors of COX-2, such as celecoxib, and inhibitors of angiogenesis, such as bevacizumab. The response rate (RR) observed combining endocrine and targeted agents ranged between 36% and 90%.

Overall the studies failed to show a remarkable advantage in RR in the combination group compared to historical control subjects receiving AIs alone.

Metformin increases survival in hormone receptor-positive, HER2-positive breast cancer patients with diabetes

Introduction

Metformin use has recently been observed to decrease both the rate and mortality of breast cancer. Our study was aim to determine whether metformin use is associated with survival in diabetic breast cancer patients by breast cancer subtype and systemic treatment.

Methods

Data from the Asan Medical Center Breast Cancer Database from 1997 to 2007 were analyzed. The study cohort comprised 6,967 nondiabetic patients, 202 diabetic patients treated with metformin, and 184 diabetic patients that did not receive metformin. Patients who were divided into three groups by diabetes status and metformin use were also divided into four subgroups by hormone receptor and HER2-neu status.

Results

In Kaplan-Meier analysis, the metformin group had a significantly better overall and cancer specific survival outcome compared with non metformin diabetic group (P <0.005 for both). There was no difference in survival between the nondiabetic and metformin groups. In multivariate analysis, Compared with metformin group, patients who did not receive metformin tended to have a higher risk of metastasis with HR 5.37 (95 % CI, 1.88 to 15.28) and breast cancer death with HR 6.51 (95 % CI, 1.88 to 15.28) on the hormone receptor-positive and HER2-negative breast cancer. The significant survival benefit of metformin observed in diabetic patients who received chemotherapy and endocrine therapy (HR for disease free survival 2.14; 95 % CI 1.14 to 4.04) was not seen in diabetic patients who did not receive these treatments.

Conclusion

Patients receiving metformin treatment when breast cancer diagnosis show a better prognosis only if they have hormone receptor-positive, HER2-positive tumors. Metformin treatment might provide a survival benefit when added to systemic therapy in diabetic patients.

Effect of Primary Letrozole Treatment on Tumor Expression of mTOR and HIF-1α and Relation to Clinical Response

INTRODUCTION

Recently the combination of the mammalian target of rapamycin (mTOR) inhibitor everolimus and the aromatase inhibitor exemestane has been shown to double the progression-free survival rate in advanced breast cancer. However, the effect of the interrelated pathways of hypoxia-inducible factor-1α (HIF-1α) and mTOR signaling, both of which are associated with a more aggressive breast cancer phenotype and endocrine resistance, on response in the neoadjuvant setting is unknown. We, therefore, have investigated the influence of these pathways with the aim of better defining those patients most likely to benefit from an endocrine-based therapy associated with/without mTOR inhibitors.

PATIENTS AND METHODS

A total of 107 women with T2-4 N0-1 and estrogen receptor-positive breast cancer were randomly assigned to 6 months of primary letrozole (2.5 mg/daily) (LET) or LET plus oral "metronomic" cyclophosphamide (50mg/daily) (LET-CYC). Phospo-mTOR and HIF-1α were evaluated in tumor specimens collected before and after treatment using a tissue microarray format.

RESULTS

LET-based therapy induced a downregulation of phospho-mTOR and HIF-1α expression (P = .0001 and P < .004, respectively). The reduction of HIF-1α expression observed was positively correlated with phospho-mTOR reduction (P < .03); however, no treatment interaction between the two proteins was detected. HIF-1α expression was significantly modulated by the treatment (P < .004) with a reduction both in the LET arm (45%, n = 36/80) (P = .05) and LET-CYC arm (55%, n = 44/80) (P = .04). HIF-1α reduction showed a relationship with clinical response confined in LET arm only (P < .03).

CONCLUSIONS

In this neoadjuvant population, LET was able to modulate the phospho-mTOR and HIF-1α pathways and may define a subpopulation of nonresponders who may be most likely to benefit from mTOR inhibitors.