FORCE has a strong commitment to promoting research to benefit our community. We advocate for more research funding, educate people about available studies, and report findings back to our community.
by Piri Welcsh, PhD
Findings from the phase III EMBARCA trial, which tested talazoparib (Pfizer), a PARP inhibitor, against physician’s choice of chemotherapy were presented by Dr. Jennifer Litton at the 2017 San Antonio Breast Cancer Symposium. The take-home message she delivered was that talazoparib a pill taken once daily extends progression-free survival (PFS) by 3 months and improves quality of life in patients with advanced breast cancer who have an inherited BRCA1 or BRCA2 mutation.
EMBRACA results: PARP inhibitors for metastatic breast cancer
The EMBRACA trial included 431 women and men with stage 4 metastatic breast cancer. All patients had a confirmed BRCA1 or 2 mutation. The trial compared talazoparib (287 patients) to physician’s choice of chemotherapy (144 patients). Patients were followed for approximately 11 months. Patients receiving talazoparib were treated for approximately 6 months; those receiving chemotherapy were treated for almost 4 months.
Results showed that patients receiving talazoparib had on average 8.6 months of PFS compared to 5.6 months for patients receiving chemotherapy. Litton, a breast medical oncologist at the University of Texas MD Anderson Cancer Center, and a member of FORCE’s Scientific Advisory Board, said, “We are very pleased that the phase III EMBRACA trial the largest randomized clinical trial conducted in this group of patients with hereditary breast cancer met its primary efficacy endpoint.”
Litton reported that patients on talazoparib experienced an increase in quality of life, while the quality of life decreased for patients who received chemotherapy. Talazoparib was equated with a 3-point improvement in quality of life compared to a 5.4 point drop with chemotherapy. Litton also noted higher rates of confirmed complete response (5.5% vs. 0%) and partial response (57.1% vs. 27.2%) for patients who received talazoparib compared to chemotherapy.
Results also showed that the PFS response for talazoparib was favorable among patients with triple-negative or hormone receptor-positive status and those who had prior chemotherapy. Talazoparib particularly improved PFS among patients with a history of brain or other central nervous system metastasis. The most common side effect of talazoparib was anemia.
Overall survival (OS) data are not yet complete; however, early results appear positive. Litton noted a median OS of 23.3 months for patients who received talazoparib compared to 19.5 months for those who received chemotherapy.
The future of PARP inhibitors in treatment of breast cancer
The EMBRACA results are important because they confirm that PARP inhibitors may be used to treat some metastatic breast cancer patients. Results of OlympiAD were presented earlier this year. OlympiAD looked at the PARP inhibitor olaparib for treating metastatic breast cancer. Like the EMBRACA trial, the OlympiAD trial showed that olaparib improved PFS by 3 months. To date, PARP inhibitors are only approved for ovarian, fallopian tube and primary peritoneal cancers. It is likely, however, that they will soon be approved for treating metastatic breast cancer. The National Comprehensive Cancer Network (NCCN), which develops guidelines for cancer, added olaparib as a preferred “single agent” for treating metastatic breast cancer.
FORCE was proud to help recruit for both the EMBRACA and OlympiAD trials; many members of our community answered the call and volunteered to participate to advance research. There are other clinical trials enrolling people with hereditary metastatic breast cancer. These can be found in the research section of our website.
One can only imagine the power of PARP inhibitors when tried, carefully, in combination with other agents, and in earlier-stage disease as is happening in trials ongoing and planned. This may be the start of a paradigm change in the way advanced hereditary breast cancer is treated.
Litton JK, et al. Abstract GS6-07. Presented at San Antonio Breast Cancer Symposium; Dec. 5-9, 2017; San Antonio.