PIK3R1 underexpression is an independent prognostic marker in breast cancer.

BACKGROUND: The present study focused on the prognostic roles of PIK3CA and PIK3R1 genes and additional PI3K pathway-associated genes in breast cancer. METHODS: The mutational and mRNA expression status of PIK3CA, PIK3R1 and AKT1, and expression status of other genes involved in the PI3K pathway (EGFR, PDK1, PTEN, AKT2, AKT3, GOLPH3, WEE1, P70S6K) were assessed in a series of 458 breast cancer samples. RESULTS: PIK3CA mutations were identified in 151 samples (33.0%) in exons 1, 2, 9 and 20. PIK3R1 mutations were found in 10 samples (2.2%) and underexpression in 283 samples (61.8%). AKT1 mutations were found in 15 samples (3.3%) and overexpression in 116 samples (25.3%). PIK3R1 underexpression tended to mutual exclusivity with PIK3CA mutations (p = 0.00097). PIK3CA mutations were associated with better metastasis-free survival and PIK3R1 underexpression was associated with poorer metastasis-free survival (p = 0.014 and p = 0.00028, respectively). By combining PIK3CA mutation and PIK3R1 expression status, four prognostic groups were identified with significantly different metastasis-free survival (p = 0.00046). On Cox multivariate regression analysis, the prognostic significance of PIK3R1 underexpression was confirmed in the total population (p = 0.0013) and in breast cancer subgroups. CONCLUSIONS: PIK3CA mutations and PIK3R1 underexpression show opposite effects on patient outcome and could become useful prognostic and predictive factors in breast cancer.

PIK3CA mutation impact on survival in breast cancer patients and in ERα, PR and ERBB2-based subgroups.

INTRODUCTION: PIK3CA is the oncogene showing the highest frequency of gain-of-function mutations in breast cancer, but the prognostic value of PIK3CA mutation status is controversial. METHODS: We investigated the prognostic significance of PIK3CA mutation status in a series of 452 patients with unilateral invasive primary breast cancer and known long-term outcome (median follow-up 10 years). RESULTS: PIK3CA mutations were identified in 151 tumors (33.4%). The frequency of PIK3CA mutations differed markedly according to hormone receptor (estrogen receptor alpha [ERα] and progesterone receptor [PR]) and ERBB2 status, ranging from 12.5% in the triple-negative subgroup (ER-/PR-/ERBB2-) to 41.1% in the HR+/ERBB2- subgroup. PIK3CA mutation was associated with significantly longer metastasis-free survival in the overall population (P = 0.0056), and especially in the PR-positive and ERBB2-positive subgroups. In Cox multivariate regression analysis, the prognostic significance of PIK3CA mutation status persisted only in the ERBB2-positive subgroup. CONCLUSIONS: This study confirms the high prevalence of PIK3CA mutations in breast cancer. PIK3CA mutation is an emerging tumor marker which might become used in treatment-choosing process. The independent prognostic value of PIK3CA mutation status in ERBB2-positive breast cancer patients should be now confirmed in larger series of patients included in randomized prospective ERBB2-based clinical trials.

High lapatinib plasma levels in breast cancer patients: risk or benefit?

AIMS AND BACKGROUND: Lapatinib is a tyrosine kinase inhibitor targeting epidermal growth factor receptors 1 (EGFR/HER1) and 2 (HER2) used in the treatment of patients with HER2-positive breast cancer. The aim of the present study was to determine lapatinib plasma levels in breast cancer patients treated with lapatinib plus capecitabine. PATIENTS AND METHODS: We assessed lapatinib plasma levels in blood samples from 21 breast cancer patients treated with lapatinib plus capecitabine using the standard regimen in an expanded access program. Liquid chromatography tandem mass spectrometry was used for measuring lapatinib plasma concentrations. The validated method was applied for measurement of 55 plasma samples. RESULTS: The median lapatinib plasma level was 5.09 µg/mL, with large interindividual differences. Patients of lower weight tended to have higher lapatinib plasma levels (Spearman correlation coefficient R = -0.435, P = 0.055). One patient's lapatinib plasma levels were markedly higher than those of the others, with a median level of 11.25 µg/mL and repeatedly exceeding 7.80 µg/mL. The treatment was terminated after 8 months when hyperbilirubinemia occurred. CONCLUSIONS: The lapatinib plasma levels reported here are twice as high as the clinically effective steady-state geometric mean maximum concentration. We conclude that increased lapatinib body levels occur when patients are in a nonfasting state at the time of drug intake and when lapatinib doses are not adjusted to low body weight or weight loss during treatment. In Europe, dose adjustments are not recommended in the case of hepatic function impairment. Thus, attention should be paid to changes in liver function test results in clinical practice, especially in patients of small stature and weight, given the risk of high plasma concentrations. Prospective lapatinib plasma level assessment in treated patients might be useful to confirm or refute the possible correlation of high lapatinib plasma levels with hepatic and/or other toxicities.

Collagen triple helix repeat containing 1 protein, periostin and versican in primary and metastatic breast cancer: an immunohistochemical study.

BACKGROUND: Collagen triple helix repeat containing 1 (CTHRC1) affects Wnt signalling, collagen deposition and bone formation. It is an extracellular matrix protein which is also abnormally expressed in the tumour microenvironment. CTHRC1 has not been studied in breast cancer by immunohistochemistry. AIMS: To examine expression of CTHRC1 together with periostin and versican in breast cancer patients and investigate its association with clinicopathological characteristics. METHODS: The formalin-fixed paraffin-embedded tissues of 173 invasive carcinomas (classified into WHO histotypes and luminal, triple negative and Her2 subtypes), as well as normal tissues, precursor lesions and metastatic lymph nodes were stained by relevant antibodies, assessed semiquantitatively by histoscore and statistically evaluated. RESULTS: Expression of CTHRC1, versican and periostin was significantly higher in breast cancer than in normal tissue or precursor lesions. CTHRC1 stromal expression was enhanced in triple negative cases and also in patients with bone metastasis. Periostin expression was high in primary tumours, in particular triple negative ones, and also in their lymph node metastases. Cox regression analysis showed that in patients with high periostin, the risk of bone metastases increased with increased CTHRC1 expression. CONCLUSIONS: CTHRC1 and periostin play important roles in breast cancer progression. These preliminary results show that combined evaluation of CTHRC1 and periostin could serve as a potential marker for breast cancer bone metastasis; the other observations contribute to the description of the tumour microenvironment, with implications for lymph node and bone metastasis.

Lapatinib in breast cancer - the predictive significance of HER1 (EGFR), HER2, PTEN and PIK3CA genes and lapatinib plasma level assessment.

BACKGROUND: Breast cancer treatment trends are currently based on tailored therapies using tumor and patient biomarkers. Lapatinib is the first dual inhibitor of HER1 (EGFR, ErbB1) and HER2 (ErbB2, Neu) tyrosine kinases to be used in clinical practice. However, only HER2 is currently used for therapy indications and new predictors for the treatment with lapatinib are sought. METHODS AND RESULTS: This minireview focuses on lapatinib and its role in breast cancer treatment. Preclinical and clinical studies as well as pharmacological characteristics are briefly reviewed while the focus is on efficacy assessment including predictive factors for therapy outcome. CONCLUSION: Lapatinib (Tykerb/Tyverb) was Food and Drug Administration (FDA) approved in 2007 for use in combination with capecitabine for the treatment of HER2-positive advanced or metastatic breast cancer in patients who had received previous treatment (including anthracycline, taxane and trastuzumab containing regimens) and in 2010 for use in combination with letrozole for postmenopausal women with hormonal receptor positive and HER2- positive metastatic breast cancer. In contrast to trastuzumab (Herceptin), lapatinib is orally administered and it targets both HER2 and HER1 receptors. As a synthetic and oral tyrosine kinase inhibitor (TKI), it is convenient, cheaper and easier to produce than monoclonal antibodies. The recommended dosage is not dependent on body weight either. Lapatinib plasma level measurement could be an approach to tailored therapy for further optimizing the dose and prolonging this efficient therapy. New lapatinib response predictors are being evaluated. At this time, only HER2 amplification/overexpression is used to choose lapatinib therapy candidates. Further studies on concurrent HER1 fluorescent in situ hybridization (FISH)/immunohistochemistry (IHC) assessment and/or microarray analyses may produce new data on the predictive role of the HER1 (EGFR) gene/protein. PTEN loss and PIK3CA gene mutations are other markers that may predict lapatinib poor response.

Gene expression profiling reveals new aspects of PIK3CA mutation in ERalpha-positive breast cancer: major implication of the Wnt signaling pathway.

BACKGROUND: The PI3K/AKT pathway plays a pivotal role in breast cancer development and maintenance. PIK3CA, encoding the PI3K catalytic subunit, is the oncogene exhibiting a high frequency of gain-of-function mutations leading to PI3K/AKT pathway activation in breast cancer. PIK3CA mutations have been observed in 30% to 40% of ERα-positive breast tumors. However the physiopathological role of PIK3CA mutations in breast tumorigenesis remains largely unclear. METHODOLOGY/PRINCIPAL FINDINGS: To identify relevant downstream target genes and signaling activated by aberrant PI3K/AKT pathway in breast tumors, we first analyzed gene expression with a pangenomic oligonucleotide microarray in a series of 43 ERα-positive tumors with and without PIK3CA mutations. Genes of interest were then investigated in 249 ERα-positive breast tumors by real-time quantitative RT-PCR. A robust collection of 19 genes was found to be differently expressed in PIK3CA-mutated tumors. PIK3CA mutations were associated with over-expression of several genes involved in the Wnt signaling pathway (WNT5A, TCF7L2, MSX2, TNFRSF11B), regulation of gene transcription (SEC14L2, MSX2, TFAP2B, NRIP3) and metal ion binding (CYP4Z1, CYP4Z2P, SLC40A1, LTF, LIMCH1). CONCLUSION/SIGNIFICANCE: This new gene set should help to understand the behavior of PIK3CA-mutated cancers and detailed knowledge of Wnt signaling activation could lead to novel therapeutic strategies.

Triple negative breast cancer--current status and prospective targeted treatment based on HER1 (EGFR), TOP2A and C-MYC gene assessment.

BACKGROUND: Every year about one million women worldwide are diagnosed with breast cancer which is the most common malignancy in female. Of these, triple negative breast carcinoma represents 10-17 %. Triple negative breast carcinomas, characterized by estrogen, progesterone and HER2 receptor negativity are very aggressive tumours with poor prognosis. Individualized treatment (tailored therapy) based on molecular biology markers of tumor and patient is the trend in clinical practice these days. However, molecular targets and predictors for the treatment of triple negative breast carcinoma do not currently exist. METHODS AND RESULTS: This minireview focuses on biomarkers (HER1/EGFR, TOP2A and C-MYC genes) that may predict the response of triple negative breast carcinoma patients to chemotherapy and/or targeted biological treatment with a summary of current knowledge about them. CONCLUSION: HER1 belonging to the HER family of receptors plays an important role in cell proliferation, migration and protection against apoptosis. HER1 protein could be targeted by monoclonal antibodies and/or tyrosine kinase inhibitors (TKIs). Given signal pathway complexity and HER family member cooperation, it may be better to simultaneously target a number of these receptors (e.g. HER1/HER2 by lapatinib). Thus, HER1 assessment could reveal a particular breast cancer patient group with probably good response to HER1 targeted therapy. TOP2A gene, encoding topoisomerase II alpha (target for anthracyclines) is predictive of response to anthracycline therapy. TOP2A aberrations (amplification, deletion) are found in up to approximately 30-90 % of HER2 amplified breast cancer and amplifications are more common than deletions. Recent publications describe TOP2A amplification also in 2.7-8.8 % HER2 nonamplified breast cancers. Patients with a pathologic complete response to anthracycline based neoadjuvant chemotherapy had a good overall prognosis regardless of molecular subtype of breast cancer. These results suggest that particularly tumors with a complete pathological response to anthracyclines could have TOP2A amplification. C-MYC encodes nuclear DNA binding proteins that regulate proliferation and apoptosis; amplification is associated with poor prognosis and hormonally negative breast carcinoma.