Posted 09 November 2012
By Alexander Gaffney, RF News Editor
The US Food and Drug Administration (FDA) has released a new draft guidance for industry regarding the development of In Vitro devices capable of detecting the presence of several types of dangerous pathogens, its latest effort in a long-running strategy to develop medical countermeasures (MCMs).
The guidance, released 9 November 2012, specifically addresses the unique needs of conducting clinical trials on such a device.
The clinical testing of products used to treat the sorts of pathogens FDA considers dangerous enough to require medical countermeasures-anthrax, for example-is often fraught with ethical concerns and dilemmas.
Because the diseases rarely exist in the general population, clinicians would need to expose patients to the disease to adequately test the product on them-an ethical violation in that such an exposure would likely harm, if not kill, some patients. Failing that, the device would not be adequately tested in real-world conditions, and could fail to protect patients if it was ever put into wider use during an emergency.
To bridge the gap between these two points, FDA has put out previous guidance regarding a so-called "Animal Pathway," a rarely-used regulatory process involving reliance on animal testing.
Unlike products intended to treat dangerous pathogens, in vitro diagnostic devices are only intended to detect the presence of pathogens, and FDA's medical countermeasure initiatives are looking to spur the development of multi-purpose devices that can detect multiple pathogens at once. FDA said it envisions those devices, known as highly multiplexed microbiological/medical countermeasures in vitro nucleic acid based diagnostic devices (HMMDs), being able to detect at least 20 different organisms or targets in a single test simultaneously.
FDA said it expects many of these devices to be cleared through its 510(k) or de novo classification pathways, and the draft guidance is specifically tailored to the use of either pathway. But the devices, it notes, are not without serious and unique risks.
"Failure of the device to perform as indicated, leading to inaccurate results or lack of results, and incorrect interpretation of results," FDA wrote. "These potential risks may lead to incorrect patient management decisions."
Alternatively, a false positive identification-the finding that a particular pathogen is present when it is not-could lead to "unnecessary or inappropriate" treatment, as well as delayed treatment for a pathogen that actually is present. Additionally, given the high-profile nature of a pathogen requiring an MCM response, a false positive could lead to a public health emergency and general panic, eroding trust in regulators and health officials.
But if an MCM is to pass through FDA easily, the 510(k) process could potentially be the approval pathway of least resistance. The pathway rarely requires sponsors to conduct clinical testing, allowing regulators and sponsors to avoid the normal ethical pitfalls associated with testing on human patients or proving that animal models show the product would work in humans.
Sponsors will, however, be subject to rigorous requirements and test methodologies to ensure their devices work as intended. FDA expects sponsors to be able to "describe, in detail, the methodology used by [their] device," including the test platform, analytical methods, limiting factors, components, controls, and the processing of data from a signal to a result.
FDA also expects sponsors to describe their design and quality control specifications used to ensure device conformity, in part to avoid the types of false-positive and false-negative results described earlier.
Requirements for each of these factors are described at length and in unusually specific detail in the guidance.
Comments on the draft guidance are due by 7 February 2012.