Emily L. Podany, MD, on Metastatic Breast Cancer: Racial Differences in Genomic Profiles and Targeted Treatment Use

The study that I'm presenting is a multicenter consortium study. It consists of 1,327 patients that we looked at both genomic data through the liquid biopsy Guardant360 and clinical data that we got manually from the electronic medical record system. We decided to use this large multi-consortium database to ask questions about targeted treatment use in Black versus White patients. So we found that Black and White patients had equal incidence of PIK3CA mutations. But despite this equal incidence, they had differences in targeted treatment use. Black patients ended up having significantly less targeted treatment use than White patients in this dataset. Specifically, this was for these PI3 kinase inhibitor use. When we looked at mTOR inhibitor use and CDK4/6 inhibitor use, which does not require a specific finding in ctDNA or liquid biopsy, we actually didn't find any differences. So the only targeted treatment use differences was when there was a specific targeted finding in the ctDNA profiling. The other thing we looked at after that was we looked at overall survival in this cohort. We'd previously reported overall survival in the overall 1,327 patients, and then we looked specifically at HR-positive HER2-negative metastatic breast cancer patients, and we looked at ER positive, PR negative HER2 negative, and ER positive, PR positive HER2 negative. The PR-negative patients did significantly worse in terms of overall survival and Black patients with ER positive, PR negative HER2 negative did significantly worse than White patients with the same profile. Finally, we looked at clinical trial enrollment, so we looked at whether the patients with this PIK3CA mutation with metastatic breast cancer were enrolled in clinical trials at the same rate between Black and White patients. So we found that Black patients were significantly less likely to be enrolled in a clinical trial than White patients.