Comparison of breast cancer prognostic tests CanAssist Breast and Oncotype DX.

BACKGROUND: CanAssist Breast (CAB) is a prognostic test for early stage hormone receptor-positive (HR+), human epidermal growth factor receptor 2 negative (HER2-) breast cancer patients, validated on Indian and Caucasian patients. The 21-gene signature Oncotype DX (ODX) is the most widely used commercially available breast cancer prognostic test. In the current study, risk stratification of CAB is compared with that done with ODX along with the respective outcomes of these patients. METHODS: A cohort of 109 early stage breast cancer patients who had previously taken the ODX test were retested with CAB, and the results respectively compared with old cut-offs of ODX as well as cut-offs suggested by TAILORx, a prospective randomized trial of ODX. Distant metastasis-free survival after 5 years was taken as the end point. RESULTS: CanAssist Breast stratified 83.5% of the cohort into low-risk and 16.5% into high-risk. With the TAILORx cut-offs, ODX stratified the cohort into 89.9% low-risk and 10.1% into high-risk. The low, intermediate, and high-risk groups with ODX old cut-offs were 62.4%, 31.2%, and 6.4%, respectively. The overall concordance of CAB with ODX using both cut-offs is 75%-76%, with ~82%-83% concordance in the low-risk category of these tests. The NPV of the low-risk category of CAB was 93.4%, and of ODX with TAILORx cut-offs was 91.8% and 89.7% with old cut-offs. CONCLUSIONS: Compared to the concordance reported for other tests, CAB shows high concordance with ODX, and in addition shows comparable performance in the patient outcomes in this cohort. CAB is thus an excellent and cost-effective alternative to ODX.

Enhancing the quality of life and preserving independence for target needs populations through integration of assistive technology devices.

Telehealth Test Bed-Quality of Life Studies is a research study investigating, testing, evaluating, and demonstrating technologies that have the potential to improve the quality of life for target populations, such as warriors in transition, veterans, individuals with physical and mental disabilities, and adults age 65 and older, who may require assistive technology devices to aid in maintaining or improving their quality of life. Thousands of soldiers who fought in Operation Iraqi Freedom and Operation Enduring Freedom have been wounded in action or have sustained injuries from noncombat accidents. Many of these injuries affecting military populations, as well as the general public, have resulted in amputations, traumatic brain injuries, and other physical or mental impairments. Depending on the severity of the injury, assistive technologies may be temporarily needed, or as a long-term solution, to regain and maintain normal daily functions. Saint Francis University's Center of Excellence for Remote and Medically Under-Served Areas developed an evaluation matrix comparing assistive technologies to identify devices that will improve or maintain the quality of life for these target populations. The integration of telehealth and telerehabilitation applications into patients' daily lives was examined to help improve home rehabilitation via access to healthcare specialties in rural and medically underserved settings. Researchers identified and tested assistive technology devices to be included in a self-sufficient living environment. The continuation of this research involves recruiting individuals to test and evaluate the functions of these commercially available technologies and to complete data collection surveys and questionnaires. The results are useful in selecting devices that will enhance or extend the quality of life of the target populations.

Structure-based design of estrogen receptor-beta selective ligands.

We present the structure-based optimization of a series of estrogen receptor-beta (ERbeta) selective ligands. X-ray cocrystal structures of these ligands complexed to both ERalpha and ERbeta are described. We also discuss how molecular modeling was used to take advantage of subtle differences between the two binding cavities in order to optimize selectivity for ERbeta over ERalpha. Quantum chemical calculations are utilized to gain insight into the mechanism of selectivity enhancement. Despite only two relatively conservative residue substitutions in the ligand binding pocket, the most selective compounds have greater than 100-fold selectivity for ERbeta relative to ERalpha when measured using a competitive radioligand binding assay.

Identification of novel estrogen receptor alpha antagonists.

We have identified novel estrogen receptor alpha (ERalpha) antagonists using both cell-based and computer-based virtual screening strategies. A mammalian two-hybrid screen was used to select compounds that disrupt the interaction between the ERalpha ligand binding domain (LBD) and the coactivator SRC-3. A virtual screen was designed to select compounds that fit onto the LxxLL peptide-binding surface of the receptor, based on the X-ray crystal structure of the ERalpha LBD complexed with a LxxLL peptide. All selected compounds effectively inhibited 17-beta-estradiol induced coactivator recruitment with potency ranging from nano-molar to micromolar. However, in contrast to classical ER antagonists, these novel inhibitors poorly displace estradiol in the ER-ligand competition assay. Nuclear magnetic resonance (NMR) suggested direct binding of these compounds to the receptors pre-complexed with estradiol and further demonstrated that no estradiol displacement occurred. Partial proteolytic enzyme digestion revealed that, when compared with 17-beta-estradiol- and 4 hydroxy-tamoxifen (4-OHT) bound receptors, at least one of these compounds might induce a unique receptor conformation. These small molecules may represent new classes of ER antagonists, and may have the potential to provide an alternative for the current anti-estrogen therapy.

Full-length estrogen receptor alpha and its ligand-binding domain adopt different conformations upon binding ligand.

The binding of ligand to a nuclear receptor causes conformational changes that can result in coactivator or corepressor recruitment and subsequent regulation of transcription. Several peptides have previously been identified that bind to the liganded estrogen receptor (ER). One interacting peptide, pepalphaII, was used in the present studies to assess the ability of ligands to induce spatial changes within both the full-length human estrogen receptor alpha (ER-alpha) and a truncated receptor containing the ligand-binding domain (LBD). pepalphaII interacted weakly with the full-length estrogen receptor alpha in the presence of both agonists and antagonists. In contrast, the interaction of pepalphaII with the truncated receptor containing the ligand-binding domain was strongly induced by antagonists and only weakly induced by agonists. Thus, the same ligand can induce different spatial configurations of the full-length and ligand-binding domain of estrogen receptor alpha as measured by pepalphaII affinity. Crystal structures of nuclear hormone receptors solved to date have used ligand-binding domains and therefore may not accurately predict surface interaction domains present in the liganded full-length receptor. Furthermore, the ability of a ligand to induce a strong interaction of pepalphaII with the estrogen receptor alpha ligand-binding domain predicts that the ligand will have greater antagonist activity on the full-length receptor.

The ligand binding profiles of estrogen receptors alpha and beta are species dependent.

Estrogens and selective estrogen receptor modulators are used for the treatment and prevention of conditions resulting from menopause. Since estrogens exert their activity by binding to nuclear receptors, there is intense interest in developing new ligands for the two known estrogen receptor subtypes, ER-alpha and ER-beta. Characterization assays used to profile new estrogen receptor ligands often utilize receptors from different species, with the assumption that they behave identically. To test this belief, we have profiled a number of estrogens, other steroids, phytoestrogens and selective estrogen receptor modulators in a solid phase radioligand binding assay using recombinant protein for human, rat, and mouse ER-alpha and ER-beta. Certain compounds show species dependent binding preferences for ER-alpha or ER-beta, leading to differences in receptor subtype selectivity. The amino acids identified by crystallography as lining the ligand binding cavity are the same among the three species, suggesting that as yet unidentified amino acids contribute to the structure of the binding site. We conclude from this analysis that the ability of a compound to selectively bind to a particular ER subtype can be species dependent.