Our Letter to the PSP Community Regarding Biogen Trial Results
By Lawrence I. Golbe, MD, Director of Scientific Affairs
The pharmaceutical company Biogen announced today that the trial of its drug for PSP, gosuranemab, has failed to slow the progression of the disease. The trial included a 12-month period during which some patients received gosuranemab, and others received placebo (a dummy infusion). The trial, named “PASSPORT,” involved 490 patients at 86 study sites in 13 countries.
Gosuranemab is an intravenously infused antibody that, it was hoped, would slow or stop the spread of the abnormal form of the tau protein in the brain. Biogen stated that gosuranemab showed no benefit relative to placebo infusions either by the PSP Rating Scale, which was the “primary outcome measure,” nor the MRI scans, spinal fluid tests, psychological tests or other neurological tests, the “secondary outcome measures.”
Most of the patients who completed the trial’s 12-month double-blind portion opted to then receive gosuranemab on an “open-label” basis, with no further possibility of placebo, until the drug is either discontinued from testing or is approved and available at drugstores. Those patients will now have to discontinue use of the drug.
The company emphasized that this decision was not driven by any safety concerns, as gosuranemab was generally very well tolerated, with minimal side effects.
A very similar anti-tau antibody was being tested in parallel by AbbVie, another pharmaceutical company. It announced in July 2019 that its antibody proved ineffective against PSP. So today’s result from Biogen, while disappointing, was not a surprise.
Another drug company will soon begin testing an antibody that is different from those of Biogen and AbbVie, and two other drug trials using very different, non-antibody-based, methods are also likely to begin in the next year. Many other drugs for PSP are in earlier stages of testing and may enter trials over the next few years.
CurePSP is working with Biogen to provide answers to questions on the trial.