Yeah, yeah. I know it’s been 15 months since my last post. I’m fine, thanks – just busy with other things. But today a kind reader from Canada named Maureen posted a comment asking where I was all this time and threw in a little flattery just to get me going. I’m a sucker for that.
So here’s the latest on the hottest topic in PSP-ology, the antibody trials. Right now, five drug companies have anti-tau antibodies in the pipeline. Two have started human trials and are in Phase 2. The others are still in laboratory phases or in the early planning for human trials. As a reminder, these antibodies are directed at the tau protein and are given by intravenous infusion, typically at intervals of a month. The idea is to intercept the misfolded, abnormally aggregated tau as it passes through the intercellular fluid between brain cells. (We still don’t know if it’s between neurons or glia or both.) The hope is to slow the spread of the disease process through the brain. This treatment would probably not improve any existing deficits, just slow the rate at which they worsen going forward.
The first drug company out of the blocks, in 2015, was Bristol-Myers Squibb, which sold its neurodegeneration division to Biogen in April 2017. This Phase 1 trial was designed only to assess safety and comprised only 48 patients, a quarter of whom received placebo. The antibody passed with flying colors, with no important side effects over the 12 months of treatment. The patients (including the 12 assigned to placebo for the first year) are continuing to receive active drug and are generating more data along the way. The protocol did include measures of efficacy, the principal one being the ability of the treatment to slow the progression of the disease relative to placebo as measured by the PSP Rating Scale. But that effect would have to have been huge to be statistically noticeable in so small a study.
That’s the purpose of the Phase 2 studies, of which 2 are in progress. The one that Biogen bought from Bristol-Myers Squibb will include 396 patients, a third of whom will receive placebo infusions. The study will take place at about 35 sites in the US, Europe and Japan. Recruitment has begun and the double-blind phase will last a year for each patient, though it will probably take about 6 months to get all of the patients entered. This study has been dubbed the “PASSPORT” study. (It looks like an acronym, but it doesn’t really abbreviate anything except that the letters “PSP” are in there somewhere.)
The one by AbbVie, another big drug company, comprises 180 patients, of whom 60 will get placebo. It will take place at 18 sites around the US plus 3 in Canada, 2 in France and one in Australia. About half of the sites are presently recruiting patients. This study is called “ARISE.” When I find out what that’s supposed to abbreviate, I’ll let you know.
You can find more info about both trials, including contact information for prospective participants, at clinicaltrials.gov. Here’s the listing for the BMS/Biogen study and here’s the link for the AbbVie study.
Maybe a future post will regale you with my random thoughts about whether anti-tau antibodies are actually likely to help.
[Full disclosure: I consult on an hourly basis for both BMS/Biogen and AbbVie in matters regarding the PSP Rating Scale, which I published in 2007 and is the principal outcome measure for both studies. I have no personal financial interest in the studies’ outcome.]
2 thoughts on “You’ve dragged me back, or: an anti-tau antibody update”
since you brought it up, can I impose upon you to regale us with your random thoughts about whether anti-tau antibodies are actually likely to help. My wife recently started the Phase 2 PASSPORT trial. We are, of course, hopeful. But we are also realistic. Some hope is better than none.
Thank you for this insightful blog.
Thanks for the compliment there at the end. You might make me come up with another post or two for a change.
It’s very tough to judge whether the anti-tau antibodies (either Biogen’s or AbbVie’s) are likely to work. The scientific basis for the antibodies (the “prion hypothesis” of spread of the pathology through the brain) continues to gain support. Both antibodies worked in mouse models of tauopathy. They both get past the human blood-brain barrier. At least the Biogen antibody knocks down the level of tau in the CSF by over 95% (which demonstrated “target engagement”). Both antibodie appear to be well tolerated by patients. Beyond that, I have no basis for judging. All sorts of neuroprotective treatment for neurodegenerative diseases have failed in human trial after looking great up to that point. So those burn scars keep me from being too optimistic about the newest ideas. Still — how many materials did Edison try as light bulb filaments until he found something that worked?