ASCO 2023: highlights in breast cancer

Abstract

SummaryThe 2023 annual meeting of the American Society of Clinical Oncology (ASCO) was again held in June 2023 in Chicago. While not immediately practice changing, results from several interesting studies in the field of breast cancer (BC) were reported. In the phase III NATALEE trial, the addition of 3 years of ribociclib to standard adjuvant endocrine therapy resulted in a significant improvement in invasive disease-free survival (iDFS), making this the second positive study of CDK4/6 inhibitors in the adjuvant setting. A subgroup analysis from the MONARCHe trial indicated sustained benefit of adjuvant abemaciclib in the subset of patients with low dose intensity. Long-term outcome of the neoadjuvant phase II PHERgain trial indicated excellent iDFS results in patients receiving neoadjuvant trastuzumab and pertuzumab without chemotherapy based upon PET metabolic response as a dynamic biomarker. In a biomarker analysis from the SOFT trial, more high-risk tumors were observed in the very young patient subset, while the PAM50 risk-of-recurrence score was not predictive for benefit of ovarian function suppression. A large retrospective analysis evaluated the role of adjuvant chemotherapy in small, node-negative triple-negative breast cancer. A clear benefit for chemotherapy was only seen in tumors > 10 mm of size. In metastatic HR-positive breast cancer, the PALMIRA trial with palbociclib beyond progression yielded negative results. An update from the PADA-1 trial again indicates the promising role of repeated liquid biopsies for treatment guidance in metastatic disease. Patritumab deruxtecan, a HER3-directed antibody–drug conjugate yielded promising response rates in HER2-negative metastatic breast cancer patients. In addition, several retrospective analyses focused on the important question of treatment sequencing.