Treatment Algorithm: The Shifting Landscape of HER2-Positive Breast Cancer

Virginia Kaklamani, MD, DSc UT Health San Antonio | Rahul Gosain, MD, MBA Wilmot Cancer Institute | Rohit Gosain, MD Roswell Park Comprehensive Cancer Center

Key Points

• Surgery followed by paclitaxel plus trastuzumab remains the standard of care for small, early-stage HER2-positive breast cancer, while TCHP (docetaxel, carboplatin, trastuzumab, pertuzumab) is preferred for larger or node-positive disease.

• Antibody-drug conjugates (ADCs) are reshaping treatment in early-stage and metastatic settings, with ongoing discussion about optimal sequencing of trastuzumab deruxtecan (T-DXd)–based regimens.

• Proactive antiemetic use and early management of pneumonitis risk are crucial to maintaining quality of life in patients with HER2-positive disease.

The treatment landscape for HER2-positive breast cancer has significantly evolved. During an episode of the Oncology Brothers podcast, cohosts Rahul Gosain, MD, MBA, of Wilmot Cancer Institute, and Rohit Gosain, MD, of Roswell Park Comprehensive Cancer Center, discussed the use of ADCs and optimized chemotherapy across early-stage and metastatic settings with Virginia Kaklamani, MD, DSc, of UT Health San Antonio.

Early-Stage HER2+ Breast Cancer

In early-stage disease, tumor size and nodal status remain central to treatment decisions. For tumors less than 2 cm and node-negative disease, surgery followed by adjuvant paclitaxel plus trastuzumab is the standard based on data from the APT trial. 

However, a refined approach is needed in patients with 3–4 cm tumors or other intermediate-risk features. Dr. Kaklamani discussed registry data from the Netherlands that demonstrated the long-term benefit of trastuzumab.

In her practice, some patients question if they can omit chemotherapy for trastuzumab alone, but Dr. Kaklamani said this is not an option. Small, nonrandomized studies from Japan and the United States evaluating trastuzumab without chemotherapy showed inferior outcomes, reinforcing that trastuzumab should not be given alone, she explained. Her recommended treatment plan is weekly paclitaxel for 12 weeks combined with trastuzumab in this setting.

Neoadjuvant Therapy in Node-Positive Disease

For tumors greater than 2 cm or node-positive disease, neoadjuvant therapy is standard. While regimens such as THP (paclitaxel or docetaxel, trastuzumab, pertuzumab) or TCHP are standard, TCHP remains the preferred standard of care for most patients. The HELEN-006 trial demonstrated comparable outcomes and a pathologic complete response (pCR) rate of 66%, offering an alternative approach for frail patients, Dr. Kaklamani said. 

Ongoing trials such as DESTINY-Breast11 may further shift the paradigm. In considering data from DESTINY-Breast05, she said it has longer follow-up, but pneumonitis risk is an important factor in treatment selection. Dr. Kaklamani favors the DESTINY-Breast05 approach over DESTINY-Breast11 based on current data.

Metastatic HER2+ Breast Cancer: What Clinical Trials Show

Beyond early-stage disease, treatment advances are also reshaping management in the metastatic setting.

A major advancement came with the recent approval of T-DXd plus pertuzumab based on data from DESTINY-Breast09. This combination is emerging as a frontline standard, with approximately 15% of patients achieving complete response. Dr. Kaklamani favors this strategy followed by maintenance therapy.

In cases with central nervous system involvement, T-DXd has demonstrated meaningful activity based on data from DESTINY-Breast12 and real-world analyses, Dr. Kaklamani explained. Moreover, she said that tucatinib-based regimens, including data from HER2CLIMB-05, provide strong options for patients with brain metastases.

Results of the PATINA trial also show promise in hormone receptor–positive, HER2-positive metastatic breast cancer. Trial data support the addition of endocrine therapy and palbociclib after completion of cytotoxic therapy.

Proactive Toxicity Management

Toxicity management across all stage settings is critical. Proactive antiemetic use, early management of pneumonitis risk, and careful monitoring for neuropathy and other adverse events help maintain quality of life while optimizing outcomes, Dr. Kaklamani explained.