Optimizing Therapy in HR+/HER2+ Breast Cancer: Balancing Endocrine, HER2-Targeted, and Chemotherapy Options

Video content above is prompted by the following:

Treatment Strategies for Triple-Positive Breast Cancer

Panel Introduction

Moderators and Panelists:

• Dr Kelly McCann, MD, PhD - Breast medical oncologist and assistant professor at the David Geffen School of Medicine at UCLA
• Dr Gregory Vidal, MD, PhD - Breast medical oncologist at West Cancer Center and Research Institute; associate professor at the University of Tennessee Health Sciences Center; director of clinical research at West Cancer Center

Key Themes:

• Triple-positive breast cancer characteristics
  • Defined as HR-positive and HER2-positive breast cancer
  • Shows different prognosis and treatment response compared with HR-negative, HER2-positive disease
  • According to SEER database, has better prognosis than HR-negative, HER2-positive breast cancer
  • About half exhibit luminal A or B phenotype (Kim et al, 2019)
• Standard treatment approaches
  • Standard of care includes taxane with pertuzumab and trastuzumab
  • Chemotherapy eventually discontinued with antiestrogen therapy added to the backbone
  • PATINA study showed adding cyclin-dependent kinase (CDK) 4/6 inhibitor to antiestrogen therapy resulted in progression-free survival benefit
• CDK 4/6 inhibitors and triplet therapy
  • monarcHER trial demonstrated better outcomes with CDK 4/6 inhibitor plus antiestrogen therapy and trastuzumab compared with chemotherapy and trastuzumab
  • PATINA trial showed adding palbociclib to maintenance therapy improved progression-free survival (44.3 months vs 29.1 months)
  • Toxicity considerations include neutropenia, gastrointestinal adverse effects, fatigue, menopausal symptoms, and cardiac monitoring requirements

Notable Insights:

• Dr Vidal noted: “Standard of care in this setting is really a taxane with pertuzumab and trastuzumab with chemotherapy eventually dropping off, and with the addition of antiestrogen therapy to that backbone.”
• Dr McCann emphasized: “I think it’s very important to remember that even though we think of triple-positive cancers as predominantly HER2 driven, that’s not necessarily true. There’s actually a lot of crosstalk between HER2 and the estrogen receptor pathways in terms of growth signals.”