5 Key Highlights from the 2018 San Antonio Breast Cancer Symposium

Researchers shared new findings on breast cancer treatment and prevention.

Last month BCRF attended the 41st Annual San Antonio Breast Cancer Symposium (SABCS), the largest annual breast cancer meeting in the world. This year’s meeting breast cancer symposium more than 7,500 attendees from 90 countries. The event presented a balance of clinical, basic and translational research in breast cancer and was the first national meeting to include programs for patient advocates.

Each year, BCRF staff attends SABCS to catch on the latest breast cancer research, connect with BCRF researchers and to represent BCRF at nightly advocacy events.

Below are highlights from the San Antonio Breast Cancer Symposium.

T-DM 1 improves disease-free survival compared to trastuzumab in patients with early-stage HER2-positive breast cancer.

In a report from the Katherine study, researchers demonstrated that the antibody-drug conjugate, T-DM 1 (Kadcyla®) was better than trastuzumab (Herceptin®) in reducing the risk of recurrence of invasive breast cancer in patients with early-stage HER2-positive breast cancer.

HER2-positive breast cancer accounts for approximately 20 percent of breast cancers. Neoadjuvant (pre-surgical) therapy of trastuzumab plus chemotherapy is typically prescribed for patients with operable (non-metastatic) disease. Not all patients, however, respond to the neoadjuvant therapy indicating a greater risk of recurrence after surgery. The Katherine study enrolled patients who fell into this category. After surgery patients were randomized to continue trastuzumab or T-DM 1.

While it is too early to determine the more effective therapy in improving overall survival, the primary analysis of breast cancer recurrence showed that patients receiving T-DM 1 were 50 percent less likely to have a recurrence than those receiving trastuzumab.

Using neoadjuvant therapy to inform prognosis and treatment options

Pre-surgical therapy – called neoadjuvant therapy–was initially used to reduce tumor burden in patients with locally advanced breast cancer. The goal was to reduce the amount of surgery required, in many cases downgrading surgery from mastectomy to breast conserving surgery or lumpectomy. Years of clinical studies, however, have suggested that the level of response to neoadjuvant therapy may also predict risk of recurrence in patients with early-stage breast cancer. 

Pathological complete response (pCR) – a condition that refers to there being no detectable invasive tumor in the breast or lymph nodes – is the measure used to predict recurrence after neoadjuvant therapy. In a multi-study analysis reported at SABCS, pCR was associated with a significant decrease in risk of recurrence, particularly among patients with early-stage triple-negative breast cancer (TNBC). The study authors noted that pCR may inform subsequent treatment, resulting in de-escalation of therapy for those with low risk of recurrence and likewise, the use of more aggressive therapy in those who do not achieve pCR following neoadjuvant therapy.

Low-dose tamoxifen in pre-invasive breast cancer reduces the risk of invasive breast cancer

Pre-invasive breast lesions including atypical ductal hyperplasia (ADH), ductal carcinoma in situ (DCIS) and lobular carcinoma in situ (LCIS) make up about 20 percent of all breast neoplasms (abnormal growths). In cases where these neoplasms are dependent on the hormone estrogen (ER-positive), therapy often includes surgery followed by anti-estrogen therapy such as tamoxifen. The side effects of anti-estrogen therapy can make it difficult for patients to complete the therapy and potentially increase their risk of invasive breast cancer.

A study conducted across 14 sites in Italy randomized 500 women with ADH, DCIS or LCIS to receive a low dose of tamoxifen (5-mg dose vs. 20-mg dose) or placebo for three years. After five years of follow up, the investigators reported that the low-dose tamoxifen reduced the risk of recurrence by 50 percent compared to placebo.  The authors noted that while there were considerably fewer adverse effects with the lower dose of tamoxifen compared to the usual dose, less than 65 percent of patients completed the full regimen.

Follow-up from TAILORx reveals racial disparity in breast cancer outcomes

A sub analysis of the TAILORx study of women with early-stage, estrogen receptor- positive, HER2-negative breast cancer showed that black women had a worse breast cancer outcome than white women despite similar Oncotype DX scores and similar therapies.

The study, presented by BCRF investigator Kathy Albain, included 9,719 patients (8,189 white, 693 black, 405 Asian, and 432 of unknown race) The researchers found that black women were 39 percent more likely to have a recurrence and 52 percent more likely to die from their disease than white women. These differences could not be accounted for in different recurrence scores, treatments or tumor pathology.

“Our results suggest that biologic differences may contribute to the significantly different outcomes of black women compared to others with breast cancer,” Dr. Albain said.

For more information on the groundbreaking TAILORx trial see our previous blog.

Biomarker predicts response to immunotherapy in patients with advanced TNBC

The IMpassion 130 trial, published in October 2018, was the first trial to show benefits of immunotherapy for TNBC. In a follow up analysis, study author and BCRF investigator Leisha Emens reported that the immune marker, PD-L1, was effective at identifying those patients most likely to respond the PD-L1 targeted therapy, atezolizumab.

Newly diagnosed patients with metastatic TNBC received chemotherapy plus atezolizumab or plus a placebo. In the interim analysis reported at SABCS, patients with PD-L1-positive tumors who receive the atezolizumab/chemotherapy regimen had an overall survival of 25 months vs. 15.5 months in those with receiving chemotherapy/placebo. There was little difference in survival benefit of the two therapies in patients whose tumors did not have the PD-L1 marker.

To learn more about this new finding, tune in to our Facebook Live interview with Dr. Emens.