PARP Inhibiter as a Treatment for Breast Cancer

Abstract

A 71-year-old female presented with left breast tumor, which she first observed at the age of 54 years, but neglected. She had a familial history of breast cancer, i.e., her mother and aunt had breast cancer. She visited our hospital, at the age of 59 years. On examination left breast cancer, she was diagnosed with cT4cN2M0 Stage IV, ER pos, PgR pos, HER2neg breast cancer. Neo-adjuvant-chemotherapy (NAC, FEC × 4, Doc × 4) was administered ; however, the result was cPD. After NAC, operation was performed. She received postoperative chest wall radiation of 50 Gy ; letrozole was the adjuvant administered. No recurrence was observed for five years after the operation. However, six years postoperatively, chest wall recurrence occurred. Three lines of endocrine therapy were administered, but all of then were unsuccessful in treating the cancer. We decided to switch to chemotherapy and started eribulin administration (9^th year after operation). Eribulin administration showed cPD in 6 months. Then mTOR inhibitor plus exemestene and CDK 4/6 inhibitor also progressed within a few months. BRCA gene analysis revealed BRCA2 mutation. PARP inhibitor was then administered. The chest wall tumor slowly shrank at 2 months after the commencement of therapy, and the arm edema also improved and continues to resolve.