FDA Approves Liquid Biopsy Test as Companion Diagnostic to Identify Treatment-Eligible Patients With BRCA1/2-Mutant, Metastatic Castration-Resistant Prostate Cancer

The FDA has approved a liquid biopsy test (FoundationOne Liquid CDx, Foundation Medicine) for all solid tumors with multiple companion diagnostic indications, including for rucaparib (Rubraca, Clovis Oncology) tablets.

Rucaparib is a treatment that has also recently been approved, making it the first poly ADP ribose polymerase (PARP) inhibitor approved for adult patients with a deleterious BRCA mutation (germline and/or somatic)-associated metastatic castration-resistant prostate cancer (mCRPC) who have been previously treated with androgen receptor-directed therapy and a taxane-based chemotherapy.

The liquid biopsy test was created as a companion diagnostic in the identification of patients who would benefit from being treated with FDA-approved targeted therapies, such as rucaparib.

“Tumors with BRCA mutations are by far the most responsive to PARP inhibitors in metastatic castration-resistant prostate cancer, and when we started development of Rubraca for mCRPC, we knew it was important to develop a plasma-based companion diagnostic for physician and patient ease of use,” said Patrick J. Mahaffy, president and CEO of Clovis Oncology, in a press release. “What we could not have foreseen was how important a plasma-based test would be in this COVID-19 environment, in which even important procedures, such as tissue-based biopsies, can be difficult to schedule for patients.”

In a trial assessing the liquid biopsy test’s efficacy, the objective response rate in BRCA-positive patients to treatment with rucaparib as determined by the new liquid test was 46% (95% CI, 31-63). In a comparable trial using clinical trial assays for BRCA-positive patients, the objective response rate was 44% (95% CI, 31-57), demonstrating that the liquid biopsy test is able to provide consistency in patient selection for treatments.

“Now that we have drugs that specifically benefit patients with BRCA mutations, the ability to identify who has these mutations is paramount,” said Celestia S. Higano, MD, FACP, a professor at the University of Washington School of Medicine, in a press release. “In contrast to tissue biopsy, a liquid biopsy is a blood-plasma test that is less invasive than a tissue biopsy for assessing germline or somatic BRCA mutations. The FDA’s approval of liquid biopsy tests represents a significant advancement for clinicians and patients to make timely decisions about treatment options.”

REFERENCE

FDA Approves FoundationOne® Liquid CDx to Serve as Rubraca® (rucaparib) Companion Diagnostic to Identify Eligible Patients with BRCA1/2-Mutant, Metastatic Castration-Resistant Prostate Cancer (mCRPC). Boulder, CO: Clovis Oncology; August 26, 2020. businesswire.com/news/home/20200826005806/en. Accessed August 27, 2020.