Targeting Prostate Cancer

The FDA has expanded the use of a molecularly targeted therapeutic to include the treatment of certain patients with prostate cancer.

prostate cancer cells
Image via National Cancer Institute

The U.S. Food and Drug Administration (FDA) has expanded the use of a therapeutic called rucaparib (Rubraca), which targets ADP-ribose polymerase (PARP) proteins, to include the treatment of certain men who have metastatic prostate cancer that has a cancer-associated mutation in either the BRCA1 gene or the BRCA2 gene (a BRCA1/2 mutation).

Prostate cancer is the second leading cause of cancer death among men living in the United States. In 2020 alone, about 33,330 men are expected to die from the disease. Most men who die from prostate cancer have metastatic disease.

Initially, men who are diagnosed with metastatic prostate cancer are often treated with therapeutics that target androgens, the hormones that fuel prostate cancer growth. When the prostate cancer stops responding to these treatments, it is referred to as castration-resistant prostate cancer.

Rucaparib was approved for treating metastatic castration-resistant prostate cancer that has a cancer-associated BRCA1/2 mutation. It is approved for use in patients who have been treated with androgen receptor–directed therapy and a taxane-based cytotoxic chemotherapeutic such as docetaxel. According to the FDA statement, patients with prostate cancer who are being treated with rucaparib should also receive standard androgen-deprivation therapy—a gonadotropin-releasing hormone (GnRH) analog—or have had bilateral orchiectomy (surgical removal of both testicles).

Cancers caused by BRCA1/2 mutations are susceptible to PARP-targeted therapeutics like rucaparib, and the molecularly targeted therapeutic was approved by the FDA for treating patients with ovarian cancer caused by BRCA1/2 mutations in December 2016.

The new rucaparib approval was based on results from the phase II TRITON2 clinical trial. The data showed that 44 percent of the 62 patients who received rucaparib had partial or complete tumor shrinkage. Tumor shrinkage lasted six or more months for 15 of the patients.

The FDA approval was rendered on May 15, 2020.