A retrospective analysis of nadir-neutropenia directed pegylated granulocyte-colony stimulating factor on febrile neutropenia rates in (neo)adjuvant breast cancer chemotherapy regimens.

BACKGROUND: Pegfilgrastim, a pegylated granulocyte colony-stimulating-factor (GCSF), reduces chemotherapy morbidity and mortality in early stage breast cancer. The optimal approach to individual patient selection for GCSF is unknown, in particular whether secondary GCSF should be given after asymptomatic neutropenia, or only after febrile neutropenia (FN). AIMS: To determine if preplanned nadir blood counts and subsequent nadir-neutropenia directed GCSF was effective to reduce rates of FN associated with (neo)adjuvant breast cancer chemotherapy. We also aimed to describe (neo)adjuvant chemotherapy and GCSF prescribing practices at our institution. METHODS: This was a retrospective electronic medical record review. The rate of FN with secondary GCSF after cycle 1 nadir-neutropenia <1.0 × 109 cells/L was compared with the rate of FN in patients who did not have cycle 1 nadir blood counts or secondary GCSF, and analyzed according to patient and treatment data. RESULTS: Between 11/4/2011 and 22/4/2018, 584 patients received (neo)adjuvant chemotherapy. Over all rates of FN were 17%, compared with 9% in patients who received primary GCSF. Rates of FN were highest in docetaxel/carboplatin/trastuzumab (TCH, 27%) and docetaxel/cyclophosphamide (TC, 27%). There were 268 patients (46%) who received primary GCSF and 238 patients (41%) who received secondary GCSF. Rates of FN did not differ between patients who received nadir-neutropenia directed secondary GCSF (6/125, 5%, 95% CI 1.1-8.6), and those who did not have nadir blood counts or secondary GCSF (0/49, 0%, 95% CI not calculable) (P = .1186). GCSF use was associated with lower rates of non-FN hospital admissions. Patients ≥65 years were more likely to have FN and non-FN admissions. Two of three treatment related deaths occurred due to FN. CONCLUSIONS: In this population, nadir-neutropenia directed secondary GCSF was not associated with reduced rates of FN. Observed rates of FN >20% in TC and TCH in routine clinical practice should guide primary GCSF use in accordance with international guidelines.

High Notch1 protein expression is an early event in breast cancer development and is associated with the HER-2 molecular subtype.

AIMS: Activation of Notch signalling results in hyperplasia and tumorigenesis in murine mammary epithelium. However, there is little information regarding the expression of Notch1 in premalignant lesions and early breast cancer. We investigated expression of Notch1 in breast cancer development and its association with molecular subtypes. METHODS AND RESULTS: Immunohistochemical expression of Notch1 was determined in a murine model of mammary carcinogenesis and in breast tissue from two cohorts of breast cancer patients, the first (n=222) comprising a histological progression series and the second an outcome series of 228 patients with operable invasive ductal carcinoma. Enhanced expression of Notch1 protein was an early event in both murine and human breast cancer development with progressive increases in expression with the development of hyperplasia and malignancy. High Notch1 was not prognostic in the outcome cohort. There was, however, a highly significant association of high Notch1 protein with the HER-2 molecular subtype of breast cancer (P=0.008). CONCLUSIONS: These data demonstrate that aberrant Notch regulation is an early event in mammary carcinogenesis and is associated with the HER-2 molecular subtype of breast cancer, and suggest the Notch signalling pathway may be a potential therapeutic target worthy of further investigation.

Cytoplasmic localization of beta-catenin is a marker of poor outcome in breast cancer patients.

Beta-catenin is involved in cell adhesion through catenin-cadherin complexes and as a transcriptional regulator in the Wnt signaling pathway. Its deregulation is important in the genesis of a number of human malignancies, particularly colorectal cancer. A range of studies has been undertaken in breast cancer, with contradictory associations reported among beta-catenin expression, clinicopathologic variables, and disease outcome. We undertook an immunohistochemical study measuring the levels and subcellular localization of beta-catenin in 292 invasive ductal breast cancers with known treatment and outcome. No association with breast cancer-specific death was observed for cytoplasmic or membrane expression alone; however, a continuous score representing both locations (membrane minus cytoplasmic expression: MTC score) was associated with a worse outcome in univariate analysis (P = 0.004), and approached significance in a multivariate analysis model that included lymph node, progesterone receptor (PR), and HER2 status (P = 0.054). Therefore, the MTC score was used for further statistical analyses due to the importance of both the subcellular location and the levels of expression of beta-catenin. An association was identified between high cytoplasmic expression (low MTC score), and high tumor grade (P = 0.004), positive Ki67 (P = 0.005), negative estrogen receptor (ER) (P = 0.005), positive HER2 (P = 0.04) status, and an active phosphoinositide 3-kinase pathway (P = 0.005), measured as PIK3CA mutations (P = 0.05) or PTEN loss (P = 0.05). Low cytoplasmic expression (high MTC score) was associated with the luminal A subtype (P = 0.004). In conclusion, a low beta-catenin MTC score is associated with an adverse outcome in breast cancer, which may be of mechanistic significance in the disease process.

Dysregulation of Hedgehog, Wnt and Notch signalling pathways in breast cancer.

There has been a significant decrease in mortality from breast cancer in the last two decades. This has been attributed to the introduction of mammographic screening and to the development of specialised therapies, notably anti-estrogens such as tamoxifen in estrogen receptor (ER) positive tumours, and adjuvant chemotherapy. More recently monoclonal antibodies such as trastuzumab directed against Her2-overexpressing tumours show significant promise in improving outcome from this aggressive subtype. While there have been significant advances, a number of clinical challenges still remain, particularly development of targeted therapies for other forms of breast cancer lacking ER or Her2, such as the aggressive basal-like carcinomas. Identification of new therapeutic targets in poor prognosis groups will be critical to further improvements in breast cancer treatment. Proper functioning of the Hedgehog, Notch and Wnt signalling pathways is required for normal development during early life and these pathways also play a key role in regulation and maintenance of stem cells. Increasing evidence implicates dysregulation of these pathways in the development and progression of a number of malignancies, including breast cancer. This review presents the current evidence for aberrations in these pathways in breast cancer and proposes that the Hedgehog, Notch and Wnt signalling pathways may represent novel therapeutic targets.