Oncology Abstracts

Endocrine resistant estrogen receptor positive (ER+) breast cancers are dependent upon cyclin-dependent kinases (CDK) 4/6 for proliferation, making them highly suitable for CDK4/6 inhibitor treatment. Despite initial efficacy, acquired resistance to CDK4/6 inhibitors is emerging and is now a major consideration in pre-clinical and clinical drug development. Current models of CDK4/6 inhibitor resistance do not mimic the clinical scenario where CDK4/6 inhibition will occur in th...

There is bidirectional interplay between PR and ER in human breast cancers. There is evidence for a reprogramming of ER chromatin binding sites with 470 genes differentially regulated by dual treatment with estrogen plus progestogen compared to estrogen alone in breast cancer cell lines. Functionally, there was an additive anti-cancer effect with the addition of natural progesterone to endocrine therapy in preclinical breast cancer models. This is a phase II multi-site, random...

Steroid hormone receptors (SHR) play a major role in the normal breast development and breast cancer progression. Estrogen receptor (ER) is expressed in approximately 75% of breast cancers, and the majority of these tumours also express the androgen receptor (AR). While ER-directed therapies have been effective in the majority of patients, a significant subset develops resistance and requires alternative treatment approaches. In the endocrine-resistant setting, emerging insigh...

The plastic cancer cell model establishes that genetically identical cancer cells undergo bi-directional conversions between the highly aggressive tumour-initiating (TIC) state and the non-TIC cell state. We have identified subpopulations of breast cancer cells that readily switch from the non-TIC to TIC state, through activation of the EMT transcription factor ZEB-1. We have shown that non-TICs of basal BrCa are uniquely endowed with this plastic phenotype due to the cell&#14...

Breast cancer is a heterogeneous disease that can be classified into a number of molecular subtypes that predict prognosis and influence clinical treatment. Cellular heterogeneity is also evident within breast cancers and plays a key role in their development, evolution and metastatic progression. How clinical heterogeneity relates to cellular heterogeneity is poorly understood. We have approached this question using single-cell RNA-Seq on 1000s of individual cells from well-e...

Estrogen Receptor (ER) signalling, upregulation of the cyclin/CDK pathway, and suppression of p53 form a critical axis controlling proliferation of ER positive breast cancer. In this setting, mutation of p53 is relatively rare and suppression of p53 function can be achieved via regulators MDM2 and MDMX. Activation of p53 by inhibition of MDM2 is a promising therapeutic target in p53 wildtype tumours and several drugs are currently in clinical trials. We hypothesised that the M...

Seventy percent of breast cancers are classified as estrogen-receptor positive (ER+) and ER is the key proliferative driver in these tumours. Clinically, ER+ patients receive ER-targeted (endocrine) therapies to inhibit ER activity and whilst these agents reduce the risk of recurrence, up to 43% patients develop drug resistance within 15 years. Hence, identification of mechanisms underlying these resistant mechanisms could extend the use of endocrine-therapies. Profound altera...

Introduction: Resistance to endocrine therapy is a major clinical problem in estrogen receptor positive (ER+) breast cancer. The androgen receptor (AR) is expressed in ~90% of all primary ER+ breast cancers and high expression of AR is associated with a better patient outcome in this tumours. However, uncertainty surrounding the role of AR in endocrine resistance is reflected in current clinical trials in which both AR agonists and antagonists are being investigated. Here, we ...

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