Avagacestat’s demise may signal the end of the line for γ-secretase inhibitors that broadly suppress the activity of all types of γ-secretase complex, including cleavage of other substrates besides amyloid precursor protein (APP). Researchers continue to study γ-secretase modulators, which aim to more selectively shift APP processing while allowing the enzyme to cleave its other substrates normally (see ARF related news story and ARF news story). Bristol-Myers Squibb is testing a γ-secretase modulator in Phase 1 trials, according to company spokeswoman Sonia Choi. Several pharmaceutical companies have γ-secretase modulators in Phase 1 or preclinical development, including the Japan-based Eisai Co. Ltd. (see ARF related news story), EnVivo Pharmaceuticals and F. Hoffmann-La Roche Ltd., Basel, Switzerland (see ARF related news story).

Avagacestat site investigators contacted by Alzforum deplored the sudden nature of the trial’s end. They had to call participants and ask them to return study medication. The investigators were not allowed to let patients continue until their next visit, where investigators could have explained the trial’s end to their patients in person. “Our patients were upset,” said one investigator, who declined attribution because (s)he was not authorized to speak publicly. Noting that internal site impressions had hinted at a biomarker response but no cognitive benefit, these investigators essentially felt that the prodromal trial was the right design for the wrong drug.—Gwyneth Dickey Zakaib.