The US Food and Drug Administration (FDA) has released the final version of a long-awaited guidance on positron emission tomography (PET) drugs, nearly 10 months after first releasing the draft version for public consideration.
PET drugs are diagnostic radiopharmaceuticals used in conjunction with a PET device, and are commonly used in oncology and neurology screenings. "The dual photons that emerge from the positron annihilation are detected by PET scanning devices to form images that map the location of the radiopharmaceutical within the body," FDA explains in its guidance.
The drugs, like nearly all new pharmaceutical products, begin their path toward marketing authorization after obtaining an investigation new drug (IND) exemption, which allows the product's sponsor to begin clinical trials.
Historically, PET drugs have been largely exempted from FDA requirements. As a result of the 1997 FDA Modernization Act, FDA embarked on a process to bring the drugs under its regulatory purview, starting with the issuance of current good manufacturing practice (CGMP) guidance for PET drugs, which was released in late 2009. All PET drug products were then required to comply with all FDA regulations by 12 December 2011, though FDA later extended that deadline to 12 June 2012.
As of now, all manufacturers of PET products are required to have submitted-or already be operating under-an approved IND, New Drug Application (NDA) or Abbreviated New Drug Application (ANDA). By 12 December 2015, all of those applications must be approved by FDA or removed from the marketing entirely.
Despite the long timeframe, FDA said it anticipates difficulty in getting the products approved. "FDA recognizes that it may be very difficult to develop NDAs for certain PET drugs that are currently in clinical use," it explained in its guidance. Historically, those difficulties are related to enrolling patients in clinical trials when a product is already freely available, but also include the cost and amount of time needed to generate data sufficient to support a drug application.
The release of the guidance marks the start of a three-year countdown for producers of radiopharmaceutical products, during which time FDA says it will not enforce its authorities against manufacturers of PET products so long as they cooperate with FDA by submitting INDs or dossiers for approval.
Much of FDA's guidance is focused on the more practical aspects of the IND submission process: how sponsors of INDs, NDAs and ANDAs should fill out their applications to the agency, which format the document uses (the common technical document, or CTD, format), the prioritization of PET products once they are submitted to the agency (they won't be), the submission of evidence regarding the drug's safe clinical use (it's complicated) and the cases in which a drug will be exempted from FDA's requirements for IND submission (rare).
The guidance, Investigational New Drug Applications for Positron Emission Tomography (PET) Drugs, and an extensive Question and Answer document detailing the guidance are available on FDA's website.