According to the U.S. FDA definition, a companion diagnostic is a medical device, often an in vitro device (IVD), which provides information that is essential for the safe and effective use of a corresponding drug or biological product. The use of a companion diagnostic will therefore help clinicians and healthcare providers determine whether a patient is likely to benefit from the drug in question and monitor the response. To date, there is no common definition of companion diagnostic in the European Union; however, this will change with the implementation of the new EU legislation on in vitro diagnostic medical devices. The use of assays that have not been specifically validated for the safety and effectiveness of a drug or biological product may deliver inaccurate results that could harm the patient. For instance, a false positive result could lead to treatment with a drug without the proven benefits, exposing the patient to potential toxic side effects from ineffective treatment. Likewise, a false negative test result could withhold or delay a potentially beneficial treatment, putting the patient at risk. Companion diagnostics help demonstrate drug efficacy and accelerate approval. They have become an important tool for improving individual patient treatment. LabPMM embraces international harmonization and partnering. We work with key opinion leaders to standardize molecular diagnostic testing and we are also partnered with pharmaceutical companies, to develop companion diagnostic tests. Our proud history of partnerships have led to outstanding work towards internationally standardized testing, as well as FDA and PMDA approval of the first companion diagnostic for acute myeloid leukemia. Companion Diagnostic Testing LabPMM Services Catalog 2019 | 11 10