Sara Soliman, Breast Oncologist and Clinical Instructor/Assistant Professor at Brown University Health, shared on X:
“Breast oncology reads of the week from ESMO26:
HORIZON-Breast06
Trastuzumab rezetecan vs chemotherapy in HER2-low MBC:
- PFS: 16.4 vs 6.8 months (HR 0.27).
- Grade ≥3 treatment-related AEs: 84% vs 68%.
Where would this fit in a crowded space where T-DXd is already well established?
Title: Trastuzumab Rezetecan in ERBB2-Low Advanced Breast Cancer: The HORIZON-Breast06 Randomized Clinical Trial
Authors: Yuanyuan Zhao, Hongxu Liu, Xiangjiao Meng, Zhihua Liu, Yan Yu, Yulong Zheng, Longhua Sun, Runxiang Yang, Jian Liu, Yanqiu Zhao, Lin Wu, Lei Yang, Zhiye Zhang, Mingjun Li, Peng Zhang, Yan Zhang, Hua Zhong, Jiuwei Cui, Zhangzhou Huang, Yanwei Yin, Manxiang Li, Fan Tong, Dan Xue, Dongqing Lv, Xufeng Li, Xian Zhang, Steve Chin, Jiaqiang Cai, Tongtong Xue, Yan Huang, Hongyun Zhao, Li Zhang
KEYNOTE-B49
Pembrolizumab + chemotherapy in HR+/HER2− MBC:
- PFS: 6.7 vs 6.0 months (HR 0.74).
- No OS benefit (HR 1.04).
Another reminder that immunotherapy has not established a routine role in HR+/HER2− MBC outside specific biomarker-defined indications.
Title: Pembrolizumab Plus Chemotherapy for HR+/HER2- PD-L1‒Positive Advanced Breast Cancer: Final Analysis of the Phase 3 KEYNOTE-B49 Study
Authors: H S Rugo, M Kok, A Goncalves, D Loirat, G Bianchini, P A Fasching, D W Cescon, R Romero Díaz, F Zagouri, E Korbenfeld, F Dalenc, Y Jerez Gilarranz, J Hashimoto, Y H Park, S-A Im, X Hu, K M Hirshfield, L Jia, K Tryfonidis, P Schmid
postMONARCH—final OS
Abemaciclib + fulvestrant vs placebo + fulvestrant after prior CDK4/6 inhibitor + endocrine therapy:
- OS: 32.1 vs 24.6 months (HR 0.80; P=.11).
- Numerical OS improvement; not statistically significant.
A possible second-line option when no actionable alterations are identified?
Title: Overall survival from the phase III postMONARCH trial of abemaciclib plus fulvestrant versus placebo plus fulvestrant for HR+, HER2- advanced breast cancer following progression on a prior CDK4/6 inhibitor plus endocrine therapy
Authors: Kevin Kalinsky, Seth A Wander, Erika Hamilton, Stephanie L Graff, Rinath Jeselsohn, Kyong Hwa Park, Umut Demirci, Miguel Martin, Rachel M Layman, Sara A Hurvitz, Sarah Sammons, Peter A Kaufman, Elizabeth Ravenberg, Sasha Amdur, Lacey M Litchfield, Giampaolo Bianchini