Two-Thirds of High-Risk Breast Cancer Patients May Avoid Chemotherapy According to Veracyte Data Presented at ASCO

Today on the show, we’re discussing a new study just presented at ASCO 2026 that could change how chemotherapy decisions are made for a large group of breast cancer patients.During ASCO we spoke with Phil Febbo, Chief Scientific and Medical Officer at Veracyte, and John Leite, the company’s Chief Commercial Officer, looking at the results from the OPTIMA study, a large prospective trial involving roughly 4,500 patients with clinically high-risk ER-positive, HER2-negative breast cancer. The study found that about two-thirds of these patients could safely avoid chemotherapy when treatment decisions were guided by the Prosigna test. “What the Optima study shows definitively is that those women with low Prosigna score do not benefit from chemotherapy,” Febbo explains. “They get all the side effects… without any benefit.”The data generated favorable attention at ASCO. The study produced prospective level 1A evidence, the highest standard for predictive testing, and addressed one of the central problems in breast cancer care: determining which patients actually benefit from chemotherapy and which patients may be exposed to toxic treatment unnecessarily. Our show also looks at the broader evolution of molecular diagnostics in oncology. Prosigna runs on whole transcriptome sequencing, creating opportunities not only for current clinical decision-making, but also for future translational research into tumor biology and treatment response. “We need the full complement of the transcriptome to understand what is the faulty circuitry and how do we shut it off therapeutically,” Leite says.Veracyte has moved quickly from clinical validation to rollout. The company already has the assay prepared for U.S. launch immediately following the ASCO presentation. If only it worked out this way every time. It’s the kind of direct through-line between biology, clinical evidence, and improvement of human life that molecular diagnostics companies strive for each year.Note: For more in-depth discussion on the OPTIMA study and the launch of Prosigna, sign up for an upcoming webinar at GenomeWeb here. This is a public episode. If you'd like to discuss this with other subscribers or get access to bonus episodes, visit www.mendelspod.com/subscribe