Future implications
The findings have important implications for the future of breast cancer treatment, Dr. Tutt said.
Olaparib was already approved for use in the metastatic setting for gBRCAm HER2-negative breast cancer in 2018 on the basis of data from the pivotal OlympiAD trial, led by Mark E. Robson, MD, and colleagues.
In the high-risk early breast cancer setting, however, recurrence rates can be high even after chemotherapy, and novel adjuvant treatments have been lacking, Dr. Tutt said.
The latest findings from OlympiA appear to represent “a major advance for the subset of patients who have inherited BRCA1 and BRCA2 mutations,” Dr. Robson said in an interview.
“The absolute differences – even with relatively short follow-up – in invasive disease-free survival are impressive, and even though overall survival is not yet statistically significant, one surely would be hopeful that with further follow-up a difference would emerge,” he said.
There was some suggestion, even in the OlympiAD trial, that the earlier patients with metastatic disease were treated with PARP inhibition, the more benefit they received, so it’s not surprising that research has moved into the early stage disease setting, he noted.
Future directions may include looking at different drug combinations as investigators did with some success in the BROCADE3 trial of the PARP inhibitor veliparib plus carboplatin and paclitaxel in metastatic gBRCAmut HER2-negative breast cancer – particularly if concerns about worsening myelosuppression when combining a PARP inhibitor and chemotherapy are attenuated with newer PARP inhibitors, he said.
“But for now, using [olaparib] after completion of conventional chemotherapy is the approach that makes the most sense,” he added.
Dr. Robson also noted that some smaller studies show “fairly dramatic pathologic complete response rates” with preoperative PARP inhibitor therapy. He said that “the idea of giving therapy even before surgery, perhaps as a de-escalation approach, is something that would be worth studying in the future.”
For now, it will be important to keep a close eye on whether there is any worsening of rates of second malignancies, especially leukemia, over time in the OlympiA trial participants.
“That was not seen in either the OlympiAD or EMBRACA study [another phase 3 study looking at PARP inhibition in advanced gBRCAmut HER2-negative breast cancer] in the metastatic setting, but obviously [the early breast cancer] population will be at risk for a longer period of time and we will need to see what the data are,” he said. “So far the results are all very encouraging, and this could lead to a new paradigm where we’re basically testing all women with breast cancer at the time of diagnosis to figure out whether or not this is an appropriate adjuvant treatment for them.”
The OlympiA trial was funded by the National Cancer Institute and AstraZeneca. Dr. Tutt has reported multiple relationships with companies including Inbiomotion, Medscape, Prime Oncology, Artios, AstraZeneca, Merck Serono, Pfizer, Merck KGaA, Roche/Genentech, Breast Cancer Now Charity, and Cancer Research UK. Dr. Robson has reported being an investigator for clinical trials of PARP inhibitors and receiving research grants (to his institution) from AstraZeneca, Merck, and Pfizer.
A version of this article first appeared on Medscape.com.