Targeted therapies are treatments aimed at specific biomarkers, such as genetic mutations, or overexpressed proteins. Tests that detect the targeted biomarker are needed to determine whether a patient would benefit from the treatment. The FDA offers an approval pathway for such tests, so-called “companion diagnostics” (CoDx), which requires that the test be evaluated alongside the drug in clinical trials. However, testing laboratories can also develop their own tests. These “laboratory-developed tests” (LDTs) are not currently regulated by the FDA. Development of LDTs is therefore much cheaper and faster (making CoDx comparatively less economically viable), but provides less evidence that these tests are indeed effective. Moreover, LDTs can be designed to test for many different biomarkers, thus making more efficient use of limited biopsy tissue, while CoDx usually only test for the one biomarker relevant for their companion drug. A recent article calls for test developers, pharmaceutical companies, insurers, and the FDA to collaborate in resolving these issues.