A twice-daily pill can dramatically reduce the risk of breast cancer recurrence in women who are genetically prone to the disease, researchers report.

The pill — olaparib (Lynparza) — works by blocking a natural enzyme called PARP that normally fixes DNA damage in healthy cells, but in these women actually promotes the growth of cancerous cells.

Early high-risk breast cancer patients taking olaparib for a year had a 42% reduced risk of cancer recurrence or death compared to those given a placebo, said lead researcher Dr. Andrew Tutt, director of the Breast Cancer Now Toby Robins Research Center at the Institute of Cancer Research in London.

“Patients who received olaparib after surgery and chemotherapy were more likely to be alive without cancer and avoid metastasis than the patients who received placebo,” he said.

These results were presented Thursday at an online meeting of the American Society of Clinical Oncology. Findings presented at meetings should be considered preliminary until published in a peer-reviewed journal.

Olaparib already is approved to treat patients with metastatic breast cancer who have mutations in the BRCA1 or BRCA2 genes. These genes typically suppress cancer, but mutations actually increase cancer risk for some people.

About 5% of breast cancers are associated with BRCA1 or BRCA2 mutations, Tutt noted.

Breast cancers that occur due to BRCA1 or BRCA2 mutations rely on the PARP enzyme to remain alive, grow and divide. Drugs called PARP inhibitors take advantage of this fact to block the enzyme and prevent the cancer from coming back.

In this clinical trial, more than 1,800 patients with stage 2 to 3 breast cancers treated with surgery and chemotherapy were randomly assigned to take either 300 milligrams of olaparib or a placebo twice a day for a year.

Patients on olaparib had a three-year invasive disease-free survival rate — no recurring breast cancer or other new cancers — of about 86%, compared with 77% for those taking a placebo, the findings showed.

Dr. Amy Tiersten is a professor of hematology and medical oncology with the Icahn School of Medicine at Mount Sinai in New York City. She said, “We have already known for some time that PARP inhibitors have activity in patients with metastatic breast cancer, but this is the first time we have seen efficacy in the early-stage setting. This study showed a substantial reduction in the risk of recurrence in this population and, therefore, the potential to cure more patients with BRCA-associated early breast cancer.”

Side effects were consistent with previous studies of olaparib, Tutt said. The most serious common side effects included anemia, lower white blood cell counts and fatigue.

Tutt said the study shows the importance of performing genetic testing on cancer patients, to look for traits and mutations that could be exploited to improve treatment and survival.

“There certainly is a case for a mindset change in the community around where we use germline genetic testing,” Tutt said. “We’ve classically thought about it as something to do to determine someone’s risk of the disease and inform perhaps other members of their family if they’ve already had it.”

Instead of just assessing risk, this genetic information can be used to save lives, Tutt noted.

Dr. Lori Pierce, president of the American Society of Clinical Oncology, agreed.

“This further highlights the importance of genetic testing in appropriate patients so that we know which patients will benefit from this therapy,” Pierce said. “I think it may even open the door to additional trials of adjuvant PARP inhibitors for other BRCA1- and 2-associated cancers.”

Olaparib can be a pricey drug. The cost for a supply of sixty 100-milligram tablets is a little more than $7,500, according to Drugs.com.

More information

Dana-Farber Cancer Institute has more about PARP inhibitors.

SOURCES: Andrew Tutt, MBChB, PhD, director, Breast Cancer Now Toby Robins Research Center, Institute of Cancer Research, London; Lori Pierce, MD, president, American Society of Clinical Oncology, Alexandria, Va.; Amy Tiersten, MD, professor, hematology and medical oncology, Icahn School of Medicine at Mount Sinai, New York City; presentation, American Society of Clinical Oncology, June 3, 2021, online

Source: HealthDay