How many weasel words can you count in this headline?
“New treatment offers potentially promising results for the possibility of slowing, stopping, or even reversing Parkinson’s disease”
This sort of hopeful (but guarded) headline is typical of science journalism about The Cure for Parkinson’s or other incurable (at least for now!) diseases. I see headlines like this so frequently that I don’t even read the articles anymore.
This article dated 2/27/19 was a little different: first of all, the Cure Du Jour sounded current and not too wacky: “naturally-occurring growth factor, Glial Cell Line Derived Neurotrophic Factor (GDNF)”. “Naturally occurring” always sounds good, and “cell line derived” (that is, from stem cells) is hot these days. Second, the hypothesis being tested sounds reasonable: “whether boosting the levels of a naturally-occurring growth factor, … (GDNF), can regenerate dying dopamine brain cells in patients with Parkinson’s and reverse their condition”. OK, fertilizer for dopamine…I’ll buy that.
Third, this research has already gone through a couple human testing stages. The typical research progression for a pharmaceutical goes something like this:
–Animal testing (challenging with Parkinson’s since animals don’t naturally get Parkinson’s)
–Human testing – Safety — Will it kill you? (small study, typically uses healthy controls)
–Human testing – Efficacy — Does it do any good? (small study, uses patients)
–Human testing — Larger scale, longer testing – side effects, long range effects
This therapy is in its third round of human testing:
“Six patients took part in the initial pilot study to assess the safety of the treatment approach.” [That’s the Safety round]
“A further 35 individuals then participated in the nine-month double blind trial, in which half were randomly assigned to receive monthly infusions of GDNF and the other half placebo infusions.” [That’s the Efficacy round.]
“After the initial nine months on GDNF or placebo, the open-label extension study took place, which explored the effects and safety of continued exposure to GDNF for another 40 weeks in the patients previously receiving GDNF (80 weeks in total) and the effects of 40 weeks of open label GDNF in those subjects who had previously received placebo for the first 40 weeks. All 41 patients randomized and treated in the parent study (prior GDNF and placebo patients) were enrolled and completed the open label extension study.”
A side comment: What is an open label extension study? This is the opposite of the classic double blind placebo test design (neither researcher nor patient know whether they’re getting the drug or the placebo). In the open label design, both researcher and patient know they are getting the drug. One scholarly article explained, “Properly designed and conducted open label extension studies can provide rigorous information on long term safety and tolerability of potential new drugs. This in turn can benefit the licensing application for the drug by providing longer term data that would otherwise not be available until after the licence was approved.”
And the final factor that makes me take this article more seriously — money of course — money raised and spent by a large reputable organization. The article mentions “The three-part multimillion-pound GDNF study was funded by Parkinson’s UK with support from The Cure Parkinson’s Trust.”
So – great! When can I go down to my local Walgreen’s and pick up a bottle of this stuff? As usual, not so fast: “Further testing of GDNF in a larger-scale study and including the use of higher doses are required to definitively determine whether GDNF has a future role as a neurorestorative treatment for Parkinson’s.”
I Googled around to see if anyone else was working on this therapy (yes). I came across this BBC documentary about this research (about 9 minutes) dated just a few days ago (March 9, 2019). Confusingly, this documentary appears to indicate the research was not successful. (Unclear results and promising therapies that go south in later, larger trials seem to be a hallmark of Parkinson’s research.) The blog post from Parkinson’s UK goes into more detail and helps pierce the confusion: “While those who received GDNF improved more than the placebo group over the 9 months, the difference between the two groups was not large enough to be statistically significant.” Twenty percent is the threshold – but keep in mind measurement of Parkinson’s symptoms is an extremely qualitative area. I long for the article that doesn’t end with the ultimate weasel words: “More research is needed.”
A poignant side note: I found out that Tom Isaacs was one of the research subjects. Tom was a legendary British Parkie activist who raised millions of pounds for Parkinson’s research and started The Cure Parkinson’s Trust. Sadly, Tom suddenly passed away 5/31/17 at age 49 of a heart condition unrelated to Parkinson’s or the research.