ASCO, Author Interviews, Breast Cancer, Brigham & Women's - Harvard / 06.06.2018
First in Class Antibody-Drug Conjugate Shows Promise in Metastatic Breast Cancer
MedicalResearch.com Interview with:
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Dr. Bardia[/caption]
Dr. Aditya Bardia MD, MPH
Assistant Professor, Medicine
Harvard Medical School
Attending Physician, Medical Oncology
Massachusetts General Hospital
MedicalResearch.com: What is the background for this study? What are the main findings?
Response: Hormone receptor-positive (HR+)/ and human epidermal growth factor receptor 2-negative (HER2-) breast cancer is the most common sub-type of breast cancer. While metastatic HR+/HER2- breast cancer is initially treated with endocrine therapy-based combinations, including CDK 4/6 inhibitors, patients eventually have disease progression, but the response rate to standard chemotherapy is low (~10-15 percent, post-taxane setting). In particular, patients with visceral disease have a poor prognosis.
In this trial, we evaluated the efficacy of sacituzumab govitecan in patients with metastatic HR+/HER2- breast cancer, who had measurable disease and had received prior therapies for metastatic breast cancer. We observed an overall response rate of 31 percent in a heavily pre-treated population (prior number of therapies for metastatic breast cancer = 5; number of patients with prior CDK 4/6 inhibitor use = 69 percent). The responses were durable (median duration of response = 7.4 months). Neutropenia was the main adverse event noted (grade 3 neutropenia = 42 percent), and two patients (3.7 percent) discontinued the clinical trial due to adverse events. The response rate in patients with visceral metastaseswas 27 percent.
Dr. Bardia[/caption]
Dr. Aditya Bardia MD, MPH
Assistant Professor, Medicine
Harvard Medical School
Attending Physician, Medical Oncology
Massachusetts General Hospital
MedicalResearch.com: What is the background for this study? What are the main findings?
Response: Hormone receptor-positive (HR+)/ and human epidermal growth factor receptor 2-negative (HER2-) breast cancer is the most common sub-type of breast cancer. While metastatic HR+/HER2- breast cancer is initially treated with endocrine therapy-based combinations, including CDK 4/6 inhibitors, patients eventually have disease progression, but the response rate to standard chemotherapy is low (~10-15 percent, post-taxane setting). In particular, patients with visceral disease have a poor prognosis.
In this trial, we evaluated the efficacy of sacituzumab govitecan in patients with metastatic HR+/HER2- breast cancer, who had measurable disease and had received prior therapies for metastatic breast cancer. We observed an overall response rate of 31 percent in a heavily pre-treated population (prior number of therapies for metastatic breast cancer = 5; number of patients with prior CDK 4/6 inhibitor use = 69 percent). The responses were durable (median duration of response = 7.4 months). Neutropenia was the main adverse event noted (grade 3 neutropenia = 42 percent), and two patients (3.7 percent) discontinued the clinical trial due to adverse events. The response rate in patients with visceral metastaseswas 27 percent. 
Dr. Jerusalem[/caption]
Dr. Guy Jerusalem, MD, PhD
CHU Sart Tilman Liege and Liege University
Liege, Belgium
MedicalResearch.com: What is the background for this study? What are the main findings?
Response: BOLERO-6 was conducted to fulfill postapproval regulatory commitments to the FDA and EMA to estimate treatment benefit with EVE + EXE vs EVE alone or CAP for ER+, HER2− ABC that had progressed on an NSAI. Everolimus plus exemestane has not previously been compared with everolimus alone or capecitabine in a randomized setting.Data describing everolimus alone are limited to a single phase 2 study of just 19 patients. Thus, the FDA deemed it important to ascertain the efficacy of everolimus alone for ER+ breast cancer, and to determine the contribution of exemestane to combination therapy with everolimus. Capecitabine is often the first chemotherapeutic agent given for ER+ breast cancer that has progressed on anti-estrogen therapy. It has a reported PFS of 4.1–7.9 months among patients with HER2-negative advanced breast cancer. However, it has a different safety profile to everolimus or exemestane, and a comparison of endocrine-based combination therapy with single-agent chemotherapy was yet to be conducted.
The median PFS with EVE + EXE (8.4 months) was consistent with BOLERO-2 (7.8 months), and compared to EVE alone here (6.8 months) corresponded to an estimated 26% reduction of risk of disease progression or death (HR 0.74).
A numerical median PFS difference was observed for CAP over EVE + EXE (9.6 vs 8.4 months), which may be attributed to various baseline characteristics favoring CAP and potential informative censoring. The median PFS with capacitabine was longer than expected based on previous trials. Interpretation of the results of BOLERO-6 must consider the limited sample size and open-label design. 
