Several years after the draft guidance was released, the U.S. Food and Drug Administration (FDA) recently finalized its guidance for in vitro diagnostic (IVD) companion diagnostic (CDx) products. Jeffrey Shuren, M.D., director of the FDA’s Center for Devices and Radiological Health, called the final guidance “generally consistent” with the 2011 draft but said it provided some clarifications for industry. The need for guidance, the FDA says, stems from the now “more common” use of therapeutic products for which an accompanying test “is essential” for the therapy to meet its labeled safety and effectiveness claims—namely the identification of subpopulations of patients for whom the treatment will be effective or pose increased risk of serious, adverse events. Additionally, an IVD CDX would be deemed essential if treatment is adjusted based on response monitoring to achieve improved safety or effectiveness. “Inadequate performance of an IVD CDx could have severe therapeutic consequences,” the FDA warns in the final guidance. Thus, a risk-based approach will be used to determine whether premarket approval or 510(k) clearance is needed for the IVD CDx. The FDA clarified that “in most circumstances an IVD CDx and its corresponding therapeutic product should be approved or cleared contemporaneously by the FDA.” […]