The San Antonio Breast Cancer Symposium (SABCS) 2025, held December 9 to 12 in San Antonio, Texas, brought clinicians, researchers, and oncology pharmacists together to highlight emerging data reshaping treatment paradigms across breast cancer subtypes. This year’s meeting emphasized breakthroughs in targeted therapies, refinements in treatment sequencing, safety considerations in supportive care, and the expanding role of pharmacists in precision oncology.

1. MONALEESA Long-Term Ribociclib Outcomes

Beyond HER2-directed therapies, SABCS 2025 featured long-term findings from the MONALEESA trials evaluating ribociclib (Kisqali; Novartis), a CDK4/6 inhibitor, in hormone receptor-positive (HR+), HER2-negative advanced disease. Updated results demonstrated robust long-term disease control, with sustained progression-free survival benefits and manageable safety profiles, reinforcing the integral role of ribociclib in standard endocrine therapy regimens. These findings reaffirm CDK4/6 inhibitors as foundational in HR+ metastatic breast cancer and provide clinicians with confidence in long-term outcomes for patients.

2. DESTINY-Breast Trial Insights Inform Standard-of-Care Shifts

Emerging analyses from the DESTINY-Breast trial portfolio showcased how expanded use of trastuzumab deruxtecan (T-DXd, Enhertu; Daiichi Sankyo) across patient populations—including HER2-positive and HER2-low cohorts—may redefine standards of care. Integrating data from these studies, speakers highlighted improvements in both systemic control and patient outcomes, broadening the antibody drug conjugates’ (ADC) impact across the spectrum of HER2 expression.

3. HER2CLIMB-05: Extending PFS With Tucatinib Maintenance

Another significant highlight came from HER2CLIMB-05, which evaluated tucatinib (Tukysa; Array BioPharma) added to maintenance trastuzumab (Herceptin; Genentech) and pertuzumab (Perjeta; Genentech) following induction therapy in metastatic HER2+ breast cancer. Results showed a substantial 8.6-month improvement in median progression-free survival (PFS)—extending time without disease progression from about 18 months to nearly 25 months. Significantly, prolonging PFS in the maintenance setting not only enhances disease control but also allows patients to remain off cytotoxic chemotherapy longer, improving quality of life. Although central nervous system (CNS) PFS was not yet mature, exploratory analyses in patients with baseline brain metastases suggested a doubling of PFS, reinforcing tucatinib’s role in CNS disease management observed in prior HER2CLIMB studies.

4. Antibody-Drug Conjugates Break Barriers in HER2-Positive Disease

A central theme at SABCS 2025 was the rapidly evolving role of ADCs in managing HER2-positive breast cancer, particularly in patients with CNS involvement. Traditional barriers posed by the blood-brain barrier have historically limited therapeutic options for brain metastases, which occur in up to 50% of patients with advanced HER2+ disease. ADCs such as T-DXd and sacituzumab govitecan (SG; Trodelvy, Gilead Sciences) demonstrated meaningful intracranial activity with durable responses. DESTINY-Breast12 data reported intracranial response rates around 50% and encouraging PFS in patients with brain metastases.

5. Safety and Dosing Considerations in Supportive Care

Amid discussions on novel therapies, SABCS also highlighted practical considerations in supportive care—particularly the use of GLP-1 agonists in oncology settings. Emphasis was placed on vigilant monitoring for gastrointestinal side effects, appropriate dose adjustments based on tolerance, and interdisciplinary coordination to mitigate adverse events while leveraging metabolic benefits that may support overall patient well-being during cancer therapy.

6. Precision Oncology: The Pharmacist’s Expanding Role

A recurring theme throughout the symposium was the critical contribution of pharmacists in driving precision oncology. With the increasing complexity of targeted agents, biomarker-guided therapy selection, and individualized dosing strategies, pharmacists are uniquely positioned to enhance therapeutic outcomes. From interpreting genomic profiles to managing drug-drug interactions and educating patients on novel regimens, oncology pharmacists are integral to multidisciplinary care teams.

Clinical and Practice Implications

Collectively, data presented at SABCS 2025 reinforce a growing momentum toward individualized treatment pathways—whether through CNS-penetrant ADCs, maintenance strategies that extend disease control, or precision dosing considerations. For clinicians and oncology pharmacists, the challenge and opportunity lie in integrating these emerging data into practice: selecting the right patients for novel regimens, balancing efficacy with safety, and ensuring supportive care paradigms evolve alongside therapeutic innovations.