The Austin company said the Phase IIb study of PTI-125 did not meet the primary endpoint, which was reducing cerebrospinal fluid levels of tau protein.
PTI-125 "significantly" reduced a secondary endpoint: CSF levels of IL1-beta, a core biomarker of neuroinflammation, Cassava Sciences said.
Maxim analyst Jason McCarthy on Friday cut his rating on Cassava to hold from buy without a price target, telling clients in a note that "a miss is a miss" and that the path forward for PTI-125 was unclear.
The company said the test was a double-blind randomized placebo-controlled study of PTI-125 in 64 patients with mild-to-moderate Alzheimer’s disease, 50 to 85 years of age. The patients recorded 16 to 26 on the Mini-Mental State Exam, or MMSE, a 30-point questionnaire that is used to measure cognitive impairment.
Participants received PTI-125 100mg, 50mg or the matching placebo, twice daily for 28 continuous days. The drug proved safe and well-tolerated, Cassava said.
The company said that the drug effects of PTI-125, if any, may have been masked in the study by high variability in levels of biomarkers of disease. In the months ahead, Cassava Sciences said, it would reanalyze CSF biomarkers from all study participants.
“Today’s top-line results disappoint and are not consistent with previous clinical experience for reasons that are unclear at the moment,” Remi Barbier, president and CEO, said in a statement.
“We plan to thoroughly analyze these top-line data, and to reanalyze CSF biomarkers from study participants, to better understand the outcome of this study. Alzheimer’s is a disease in dire need of new treatments"
Barbier added that "it is worth reflecting on what we can learn from this study and how to move forward with drug development plans for PTI-125 in Alzheimer’s disease."