DMBN: Has there been any instance of somebody getting sick from the radiation of a radiopharmaceutical?

HW: Not to my knowledge. One of the major things is that these are given in quantities that are hundreds of times less than the toxic amounts.


DMBN: So they're essentially micro-doses?

HW: Yes. You're talking about 1/100th of a toxic dose or 1/500th of a toxic dose. I don't know of anybody that has had any deleterious side effects from having one of these studies.

DMBN: You once said it was possible to make thousands of different PET isotopes, is that right?

HW: The number is actually limitless.

DMBN: Fluorodioxyglucose, or FDG, is used in about 95% of all PET studies. So, why aren't there hundreds or thousands of radiotracers?

HW: Because the pharmaceutical industry is interested in blockbuster drugs-therapeutic drugs. For example, if you introduce a new drug, diagnostic PET tracer, it costs $500,000 just to do the toxicity testing, even though you're giving 1/100th or 1/500th of the toxic dose.

The core problem is it costs tens of millions to get one of these new PET agents approved for clinical use.
The limiting factor right now is regulation - the FDA. Their mindset is so linked to therapeutic drugs that they cannot simplify things enough to make them appropriate for non-toxic radiopharmaceuticals that are given to provide information.

"The limiting factor right now is regulation by the FDA. The problem is that their mindset is so linked to therapeutic drugs, that they cannot simplify things enough to make them appropriate for non-toxic drugs that are given to provide information."


DMBN: So the FDA sees everything radioactive as toxic?

HW: No. Not in the doses that are used for PET scans. The radiation is toxic if you get large doses of it. In fact, that's the basis of radionucleide therapy. You get the information from these very small doses that you call micro-doses. That gives you the information about a disease. Then if you want to treat a cancer or something like that, then you give big doses, which really should be judged the same way as you do stable drugs. But the tracer drugs should be judged, in my opinion, according to whether they provide the information that they are designed to provide.

DMBN: So is the problem the economics or the FDA?

HW: Well, the economics are driven by the regulation. As I said, the FDA is the one that requires the $500,000 toxicity test, and the clinical tests. Regulation is very expensive. It costs a huge amount of money for a big pharmaceutical company to develop a therapeutic drug you're looking at development costs of easily $100 million and up. For PET traces, we're talking about $20-$30 million, but the market for these diagnostic tests is minuscule compared to these blockbuster drugs that are used for therapy. So big pharma doesn't invest.

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