Dana-Farber Researchers to Present Findings at 2023 San Antonio Breast Cancer Symposium

Adrienne Waks, MD, MPH

Researchers from Dana-Farber Cancer Institute will present more than 30 research studies at the 46th annual San Antonio Breast Cancer Symposium, December 5–9, 2023. The San Antonio Breast Cancer Symposium is the world's most comprehensive academic breast cancer meeting, attracting thousands of breast cancer professionals from across the globe.

Select presentations by Dana-Farber researchers include:

RF02-06 AVIATOR/TBCRC045: A Randomized Phase II Study of Vinorelbine (N) + Trastuzumab (H) Alone or Combined With Avelumab (A) +/- Utomilumab (U) in Patients (pts) With HER2+ Metastatic Breast Cancer

Presenter: Adrienne Waks, MD, MPH
Date & Time: Thursday, December 7, 12:00 pm

Adding an immunotherapy agent to the standard therapy for HER2+ metastatic breast cancer can significantly extend the time in which the disease is held in check, a clinical trial led by Dana-Farber Cancer Institute investigators indicates. The phase II trial, dubbed AVIATOR, compared three treatment regimens in 100 patients previously treated for metastatic HER2+ breast cancer: standard therapy (chemotherapy plus the HER2-targeting drug trastuzumab); standard therapy plus avelumab.

At a median follow-up of six months, 31.2% of the patients treated with standard therapy plus avelumab were alive with no worsening of their disease, compared to 18.8% of those receiving standard therapy alone. The addition of utomilumab provided no additional benefit. Overall, 20% of patients in the standard therapy-plus-avelumab group responded to the therapy – with at least a partial reduction in their cancer – compared to 11.1% in the standard therapy group and 11.8% in the standard therapy-aveluamb-utomilumab group.

GS03-09 Characterization and Proposed Therapeutic Exploitation of Fusion RNAs in Metastatic Breast Cancers

Presenter: Nolan Priedigkeit, MD
Date & Time: Friday, December 8, 7:15 am

***Results to be presented at the SABCS press conference on Friday, December 8, 7:30 am CT.

PS08-09 Impact of HER2 Expression Dynamics on the Real-World Activity of Trastuzumab Deruxtecan for Metastatic Breast Cancer (RELIEVE)

Presenter: Paolo Tarantino, MD
Date & Time: Wednesday, December 6, 5:30 pm

Patients with metastatic breast cancer receiving trastuzumab-deruxtecan (T-DXd) – an antibody-drug conjugate – fared best if they had HER2+ disease or stable HER2-low disease, compared with those experiencing changes in HER2 status, according to a new study. T-DXd is a standard treatment for patients with HER2+ and HER2-low metastatic breast cancer. Over time, however, HER2 status can change between the primary tumor and metastatic recurrence. This study, called RELIEVE, examined how HER2 status and its changes to status influence real-world outcomes.

The team analyzed data from 191 patients with metastatic breast cancer who had been treated with T-DXd at Dana-Farber Cancer Institute and Duke Cancer Center. At the first follow-up, patients with HER2-positive disease stayed on T-DXd without progression, death or change in treatment, a measure called time to next treatment, for a median of 10.4 months. Patients with HER2-low disease had a median time to next treatment of 7.6 months, and patients with HER2-0 disease 3.7 months. Patients with stable HER2-low disease between their primary diagnosis and pre-T-DXd biopsy had a longer median time to next treatment than those with disease that switched between HER2-low and HER2-0. The study suggests that T-DXd has promising real-world activity in pretreated patients with HER2+ or stable HER2-low disease. Notably, the performance of treatments administered immediately after progression on T-DXd were short, suggesting that more options are needed in this setting.

PS06-07 Liquid Biopsy Determination of HER2 Status in Breast Cancer: Results From a Novel Epigenomic Platform

Presenter: Heather Parsons, MD
Date & Time: Wednesday, December 6, 12:00 pm

A blood test that searches for markers of gene activity can reliably determine whether a patient's breast cancer is HER2-positive or -negative, Dana-Farber Cancer Institute scientists report in a new study. Such information is critical to deciding how the cancer is to be treated.

The study findings suggest that this type of blood test – known as a liquid biopsy – can overcome the limitations of traditional methods of checking the HER2 status of breast cancer as the disease progresses, researchers say. The new technique requires only a small blood sample and, potentially, is sensitive to subtle differences in HER2 levels in tumor cells.

Parsons and her colleagues identified 20 patients with metastatic breast cancer that was HER2-positive and six whose cancer was HER2-negative. All the patients had had blood samples collected at the time of their biopsies. Researchers analyzed the cell-free DNA within the samples for specific types of epigenetic changes within sections of the DNA that control gene activity. Using a statistical model, they found the technique was highly reliable in determining whether cancers were HER2-positive or -negative. Researchers say that if it proves adept at classifying other HER2 states – such as HER2-low, in which tumor cells have small amounts of the protein – it could address the limitations of current tissue-based testing techniques.

PS11-01 Brain Metastases in Metastatic Breast Cancer: Prevalence per Line of Treatment and Cumulative Incidence in a Cohort of 18,075 Real-World Patients

Presenter: Sarah Sammons, MD
Date & Time: Thursday, December 7, 7:00 am

For patients with metastatic breast cancer, the risk of spread to the brain is higher in some molecular subtypes of the disease than others, an analysis of data from nearly 17,000 patients indicates. The risk also increases as patients undergo more lines of treatment according to Dana-Farber investigators. An analysis led by Sarah Sammons, MD, showed that the cumulative incidence of brain metastasis was highest in patients whose breast cancer was hormone receptor-negative, HER2-positive, or triple-negative. The incidence was lowest among those whose cancer was both hormone receptor-positive and HER2-negative.

For the study, researchers focused on 16,973 patients with metastatic breast cancer but no brain metastases. Over the next five years, 2,248 of them – representing 13.2% of the total group – developed brain metastases.

By the time patients were receiving their fourth line of therapy, 26.1% of those with hormone receptor (HR)-positive, HER2-positive breast cancer had a brain metastasis, as did 37.1% of those with HR-negative, HER2-positive breast cancer and 24.7% of those with triple-negative breast cancer. By contrast, only 7.2% of those with HR-positive, HER2-negative had had the disease spread to their brain.