Dr Carey on Response-Guided Therapy in HER2+ Breast Cancer

Lisa A. Carey MD, ScM, FASCO, L. Richardson and Marilyn Jacobs Preyer Distinguished Professor for Breast Cancer Research, Department of Medicine, Division of Oncology, University of North Carolina, deputy director of Clinical Sciences, Lineberger Comprehensive Cancer Center, discusses the varying approaches to response-guided therapy in HER2-positive breast cancer.

The only group of patients with HER2-positive breast cancer who don’t already receive response-guided therapy are those with small, node-negative tumors, Carey says. All other patients with early HER2-positive disease will receive neoadjuvant therapy, response to which informs subsequent therapy, Carey adds. Moreover, the phase 2 CompassHER2-pCR trial (NCT04266249) and the phase 3 CompassHER2-RD trial (NCT04457596) are important data sets that will drive de-escalated approaches when the cancer is responsive, and escalated approaches if it is more resistant and needs additional treatment, Carey notes.

Additionally, the phase 2 PHERGain trial (NCT03161353) is evaluating patients, half of whom received docetaxel plus carboplatin in combination with trastuzumab (Herceptin) and pertuzumab (Perjeta; HP; group A), while the other half received HP alone (group B). After two cycles in group B, investigators performed a PET scan and if patients showed an early marker of response, patients could continue HP alone, Carey emphasizes. If successful, this trial will support the use of an all-biologic regimen with no chemotherapy in this population, Carey says. Data thus far have shown that 40% of patients were able to achieve pathologic complete response with HP alone, which is encouraging, Carey notes.

Another tool that can inform the intensity of treatment is the HER2DX assay, Carey says. HER2DX is a prognostic and predictive assay that integrates features that are important in how HER2-positive breast cancers respond to therapy, including immune activation, as well as intrinsic subtype, Carey concludes.