Use of pertuzumab and trastuzumab during pregnancy

Trastuzumab and pertuzumab are monoclonal antibodies used for the treatment of breast cancer. Until now, there have been no reports on the use of pertuzumab during pregnancy and on its potential effects on the fetus. Herein, we present a breast cancer patient who received trastuzumab and pertuzumab treatment during the first 20 weeks of pregnancy. This 22-year-old patient initially diagnosed with invasive ductal carcinoma of the breast was found to be negative for estrogen receptor and progesterone receptor and positive for human epidermal growth factor receptor in the immunohistochemical examination. At the time of diagnosis, she had metastatic lesions and a protocol of docetaxel, trastuzumab, pertuzumab, q21, and zolendronic acid 4 mg every month was started. Following six courses of therapy, she had near-complete response, and, after administration of the same course of treatment for two additional cycles, treatment with pertuzumab plus trastuzumab was continued. While she was being followed-up with remission, a 20-week pregnancy was detected. A fetal ultrasound examination showed oligohydramnios and right renal agenesis. Treatment was stopped, and the fetus was monitored. After 7 weeks of follow-up, fetal growth retardation and anhydramnios were detected. The pregnancy was terminated. Fetal autopsy showed no urinary system pathology, but macroscopic and microscopic hyperplasia of the right adrenal gland was identified. Concomitant use of pertuzumab and trastuzumab during pregnancy may be associated with an unresolved oligohydramnios and/or anhydramnios risk. Extreme caution should be used when these monoclonal antibodies are administered during pregnancy.