Breast cancer: a new treatment in the hereditary form

Olaparib, an oral therapy already used in ovarian cancer, has just been approved in the United States for breast cancers with a BRCA mutation.

Finally new in breast cancer. Olaparib, a new oral drug, has just been licensed in the United States in a hereditary form of breast cancer linked to the presence of a BRCA mutation. These genetic abnormalities, present in 10 to 15% of breast cancers, have been popularized by actress Angelina Jolie and her decision to carry out a double preventive mastectomy.

Expected since summer 2017, this authorization makes olaparib the first targeted treatment in this hereditary form of breast cancer. Already used in ovarian cancer since 2014 (under the name Lynparza), this innovative drug takes place in the second line in advanced breast cancer after the failure of a first chemotherapy. It works by targeting the DNA repair system.

Prevent cancer cells from repairing themselves

Every cell in the body has a DNA repair device. A mutation of the BRCA1 or BRCA2 gene, inherited, prevents some of these repairs from occurring. A grain of sand in the machine, which increases the risk for each cell to accumulate genetic abnormalities and become cancerous. Women carrying a BRCA mutation have a major risk of developing breast cancer: about 70% over a lifetime.

Paradoxically, olaparib (a drug called "PARP inhibitor", the only one on the market today) also has the effect of increasing genetic instability, by inhibiting a major pathway of DNA repair. Normal cells have an escape route. But cancer cells affected by a BRCA mutation do not have this recourse available: failing to repair their damaged DNA, they end up accumulating fatal genetic failures.

A hope for "triple-negative" cancers

The pivotal study, which demonstrated the effectiveness of the molecule, shows modest efficacy: on average, olaparib can delay the progression of the disease by three months. But it is better tolerated than chemotherapy, resulting in a gain in quality of life for patients, and is more effective in breast cancers called "triple-negative", resistant to other targeted treatments.

For now, the molecule is not allowed in Europe. But US approval is usually ahead of the European Medicines Agency. The marketing authorization extension, which will make it possible to use olaparib in France in breast cancer, should therefore rapidly cross the Atlantic.

Video: Dr. Mohebtash Discusses Breast Cancer and Genetic Counseling (December 2019).