The U.S. FDA has commenced with a pilot program for companion diagnostics (CDx) for oncology therapies, which fulfills in part a 2014 agency guidance on the use of CDx. The FDA expects to enroll only nine reference drugs and the associated companion test, but the pilot program is part of the FDA’s controversial attempt to deal with lab-developed tests (LDTs), specifically those tests that are used to determine whether a patient is likely to respond to a particular oncology treatment.