FDA issued a draft guidance for industry comment that contains proposed policy for diagnostic tests used with targeted drug therapies (i.e., personalized medicine). Companion diagnostics are used to help healthcare professionals determine whether a patient with a particular disease or condition should receive a particular drug therapy or how much of the drug to give, according to the press release about the guidance. The draft guidance discusses the agency’s plans for how it will review a companion diagnostic and its corresponding therapy.

The draft guidance defines a companion diagnostic and its use. According to the release, for example, looking for a specific gene amplicfication in a patient that may predict whether a drug would benefit that patient. Herceptin (trastuzumab), approved in 1998, for instance, targets HER2 gene amplification or HER2 protein over-expression in potential breast cancer patients. Herceptin “was approved with a companion test and today testing is routinely performed on women diagnosed with breast cancer to help health care professionals determine whether or not the patient should receive” it, says the release.

The draft guidance calls for early engagement between FDA and manufacturers so that the agency’s expectations can be included in development plans, and states that FDA will aim to conduct simultaneous reviews of a drug or biologic therapy and its corresponding companion diagnostic. The document also notes instances in which the agency may approve a targeted medicine in the absence of a cleared or approved companion diagnostic (e.g., in cases where the therapy is intended to treat a serious or life-threatening disease or condition for which there is no available or satisfactory treatment and when the potential benefits outweigh the risks of not having a cleared or approved companion diagnostic, states the release).

Comments on the draft guidance are due Sept. 12, 2011.