Dr Torres on Treatment With ADCs in Breast Cancer

Mylin A. Torres, MD, professor, vice chair, Academic Operations, Department of Radiation Oncology, Emory University School of Medicine, co-leader, Cancer Prevention and Control Research Program, Winship Cancer Institute of Emory University, discusses using antibody-drug conjugates (ADCs) to treat patients with breast cancer.

Torres begins by stating that is has become evident that significant gaps exist in understanding the ideal sequencing and timing of radiation therapy for brain metastasis caused by breast cancer. This is particularly noteworthy given the recent advancements in systemic therapies over the past 5 to 10 years, she says. The lack of prospective data with radiation therapy poses a challenge in determining when to initiate radiation treatment, especially in patients undergoing concurrent therapies, such as CDK 4/6 inhibitors, immunotherapy, and HER2-directed treatments, including the latest ADCs and PARP inhibitors, Torres notes.

In a presentation given at the 2023 Bridging the Gaps in Breast Cancer meeting, Torres delved into the current treatment paradigm for patients with breast cancer brain metastases, which is primarily informed by real-world experiences. For patients with hormone receptor-positive or HER2-negative breast cancer, radiation therapy concurrently with hormone therapies such as tamoxifen, fulvestrant (Faslodex), or aromatase inhibitors, appears safe and effective, she explains. Similarly, radiation therapy seems safe for patients receiving trastuzumab (Herceptin), pertuzumab (Perjeta), or lapatinib (Tykerb), she states. However, recent data from Memorial Sloan Kettering Cancer Center, which involved approximately 98 patients treated with ADCs, indicates that a higher incidence of symptomatic radiation necrosis is observed when radiation is given within 7 days of receiving an ADC or 21 days after, she adds. Although these findings are based on a small patient population, they signal that caution is necessary when delivering radiation therapy to patients with breast cancer brain metastasis, Torres emphasizes.

Emerging research explores combinations of immunotherapy and stereotactic radiosurgery or whole-brain radiation treatment, particularly in patients with triple-negative disease, Torres notes. Insights from studies in patients with lung cancer or melanoma indicate the safety and efficacy of combining radiation therapy with immunotherapy, she continues. However, this combination increases the potential for radiation necrosis, especially with radioimmunoassay radiation or dual immune checkpoint inhibition. Ongoing clinical trials in the phase 1 and phase 2 settings aim to further investigate this combination and its implications, Torres concludes.