ASCO 2021: PARP Inhibitor Improves Disease-Free Survival in High-Risk Early Breast Cancer

Treatment with poly adenosine diphosphate-ribose polymerase (PARP) inhibitors significantly improved disease-free survival in patients with high-risk early-stage HER2-negative breast cancer with BRCA 1/2 mutations, according to new data from the OlympiA phase 3 study.

Compared with the placebo group, more patients receiving olaparib in the study were alive and free from invasive disease at 3 years, with a difference of 8.8% between both groups.

The results were presented as late-breaking data at the 2021 American Society of Clinical Oncology (ASCO) meeting, being held virtually June 4 to 8.

Lead study author Andrew Tutt, MB, ChB, PhD, FMedSci, the Institute of Cancer Research and Kings College London, presented the findings in a presscast on held on May 28.

The OlympiA trial tested the PARP inhibitor olaparib as adjuvant therapy after adjuvant or neoadjuvant chemotherapy in patients with germline BRCA 1/2 mutations and high-risk HER2-negative early breast cancer. The primary end point was invasive disease-free survival, and the secondary end points were distant disease-free survival, overall survival, and health-related quality of life.

The main results of the study are as follows:

• Compared with placebo, patients treated with olaparib had a 42% reduction in the risk of local recurrence of breast cancer, metastatic recurrence, other new cancers, and death due to any cause (invasive disease-free survival).
• Compared with placebo, patients receiving olaparib had a 42% reduction in the risk of a combination of metastatic breast cancer, new cancer, and death due to any cause (distant disease-free survival).
• OS is immature at the primary end point interim analysis. Follow-up is ongoing.

The study included germline BRCA mutation carriers with HER2-negative breast cancer who completed standard treatments. These patients were then randomized to a year of olaparib treatment or a placebo.

“Outcome is good for many patients with germline BRCA mutations and early breast cancer receiving standard treatments but recurrence rates remain high for some and so additional or adjuvant novel targeted treatments are needed,” Tutt explained. Olaparib, which is already approved in the metastatic breast cancer setting for germline mutation carriers, targets a DNA repair defect in these cancers.

The adverse effects reported in the trial were consistent with what is known for olaparib, Tutt said. Tutt noted some increases in the lower-grade AEs such as nausea, fatigue, anemia, and effects on the white blood cell counts in the olaparib group.

“The OlympiA study is the first study to report the benefits of a PARP inhibitor (olaparib) as an adjuvant treatment for early forms of germline BRCA 1/2-mutation-associated cancer,” Tutt said. “These results suggest olaparib for 1 year after standard of care treatments provides meaningful benefit to germline BRCA-mutation carriers with high recurrence risk early HER2-negative breast cancer.”

Additionally, the findings indicate that germline testing for BRCA 1/2 mutations can help influence treatment decisions in this patient population.

References

1. Tutt A, Garber JE, Kaufman B, Viale G, et al. OlympiA: A phase III, multicenter, randomized, placebo-controlled trial of adjuvant olaparib after (neo)adjuvant chemotherapy in patients with germline BRCA1/2mutations and high-risk HER2-negative early breast cancer. Presented at: 2021 American Society of Clinical Oncology; June 4-8, 2021; virtual. https://meetinglibrary.asco.org/record/196707/abstract
2. Tutt A. OlympiA: A phase III, multicenter, randomized, placebo-controlled trial of adjuvant olaparib after (neo)adjuvant chemotherapy in patients with germline BRCA1/2 mutations and high-risk HER2-negative early breast cancer. Presscast. Presented at: 2021 American Society of Clinical Oncology; May 28, 2021; virtual.