I have some bad news. Another experimental drug has failed to slow the progression of PSP. The double-blind Phase 2 trial of RT-001 in 40 participants took place in Munich, Germany. The company, BioJiva, has given me permission to discuss this ahead of their press release.
RT-001 has a unique mechanism of action. It’s based on the ample evidence that a major part of the problem in PSP is an attack on brain cells’ membranes by “reactive oxygen species.” ROS, a product of dysfunction of the mitochondria, damage the fatty acids, a major component of cell membranes. The drug is one of those fatty acids, linoleic acid, but with a twist. Two of the hydrogen atoms in the molecule are replaced by deuterium, which is hydrogen with an extra neutron in its nucleus. (Water made with deuterium instead of hydrogen is called “heavy water.”) The drug is incorporated into the membranes as if it were ordinary linoleic acid, but the two deuteriums protect it against attack by the ROS.
Sound crazy, you say? Naïve, maybe? Well, it may actually work in another disease with too much ROS activity, amyotrophic lateral sclerosis! BioJiva announced last year that an early-phase trial in ALS gave favorable, albeit undramatic results, with a 23% slower rate of decline relative to the placebo group. So, the company will continue to pursue work with RT-001 in ALS, but not in PSP.
But take heart, PSP community. There are still five PSP neuroprotection trials in progress using fasudil, TPN-101, NIO-752, sodium selenate, and AZP2006. Then, of course, there are multiple trials of “symptomatic” treatment. See my recent post for details.
Which of those five PSP neuroprotection candidates is most likely to work? I wish I (or anyone) knew enough about the molecular and cellular abnormalities underlying PSP to answer that question.
Disclaimer: I don’t own any stock in BioJiva or have any other financial relationship with them. Their Chief Medical Officer gave a presentation on the then-ongoing trial at CurePSP’s “Neuro2022” symposium in New York in October, where I was one of the organizers and moderators.