Breast cancer pharmacogenomics: where we are going

Knowledge and Attitudes About Genetic Testing Among Black and White Women with Breast Cancer

Prior to embarking on a large descriptive evaluation of genetic/racial variations in symptom phenotype, we sought foundational information to determine racial differences in (1) feasibility (consent) and acceptability of collecting genomic samples, (2) genetic literacy, and (3) concerns of genomic research during breast cancer (BC) chemotherapy. Women with early-stage BC undergoing chemotherapy were recruited from an academic, urban breast care center. Information was collected for consent to participate, genetic literacy, and concerns about genetic testing in Black and White women with BC. Fifty-six women were eligible, and 48 were consented (24 Black, 24 White). All participants consented to blood testing. This highly educated sample's mean age was 52.5 + 12.05 (years). Education (years) and genetic knowledge were positively correlated (p = .038). Genetic scores were high, and only one question significantly differed by race. On interview, most participants thought conducting genetic research helped to better understand hereditary disease and/or identify genes that cause disease and stated that they participated in the research to help other people. The majority of participants responded that friends/family would participate in genetic research without concerns, though three Black participants cited mistrust as a possible concern. Overall, there were high levels of genetic knowledge, slightly different between Black and White women. There were no high levels of personal concern regarding genetic testing. Black women reported more concern than White women that friends/family would have hesitations about participating in genetic research. There was general acceptability of blood collection for genetic testing among women with early-stage BC without racial difference.

Pharmacogenetics of response to neoadjuvant paclitaxel treatment for locally advanced breast cancer

Locally advanced breast cancer (LABC) cases have a varying five-year survival rate, mainly influenced by the tumor response to chemotherapy. Paclitaxel activity (response rate) varies across populations from 21.5% to 84%. There are some reports on genetic traits and paclitaxel; however, there is still considerable residual unexplained variability. In this study, we aimed to test the association between eleven novel markers and tumor response to paclitaxel and to explore if any of them influenced tumor protein expression. We studied a cohort of 140 women with LABC. At baseline, we collected a blood sample (for genotyping), fine needle aspirates (for Western blot), and tumor measurements by imaging. After follow-up, we ascertained the response to paclitaxel monotherapy by comparing the percent change in the pre-, post- tumor measurements after treatment. To allocate exposure, we genotyped eleven SNPs with TaqMan probes on RT-PCR and regressed them to tumor response using linear modeling. In addition, we compared protein expression, between breast tumors and healthy controls, of those genes whose genetic markers were significantly associated with tumor response. After adjusting for multiple clinical covariates, SNPs on the LPHN2, ROBO1, SNTG1, and GRIK1 genes were significant independent predictors of poor tumor response (tumor growth) despite paclitaxel treatment. Moreover, proteins encoded by those genes are significantly downregulated in breast tumor samples.