As the scientific community continues to debate the validity of Cassava Sciences’ clinical data for the Alzheimer’s disease candidate simufilam, the biotech is hoping some interim results will soothe worried investors.
The Texas biotech on Wednesday rolled out some top-line data from a 12-month interim analysis of simufilam in an open-label study funded by the National Institutes of Health. Cassava says the therapy improved cognition scores compared to baseline in the first 50 patients to complete 12 months of treatment. Improvement was seen in 68% of those patients, who had mild-to-moderate Alzheimer’s when entering the trial.
These results were analyzed by two consulting biostatisticians “to emphasize impartiality,” Cassava said.
That part is key because Cassava has been accused of manipulating data and images from data used to support the efficacy of simufilam at medical conferences. A citizens petition was filed last month questioning the scientific integrity of the company's simufilam trials and urging the agency to put them on hold.
Cassava’s shares have plummeted since then, dropping from around $117 in mid-August to around $50 as the markets opened Wednesday morning. The shares were trending down at the time, but just 4% from the prior day.
“I feel energized and encouraged by the clinical data,” President and CEO Remi Barbier said in a statement about the interim release.
The biotech is now planning to start a pivotal phase 3 study, the chief executive added, after reaching an agreement with the FDA on study protocol last month. That trial will get underway in the fourth quarter.
Cassava provided more information than usual on how the latest results were reached, including an explanation of the data's chain of custody. The company also explained that, while open-label studies are common after phase 3 trials, they are going ahead with this extension earlier in the clinical development process to prove the therapy works before a larger clinical effort.
This extension trial started in March 2020 with research funding from the NIH, according to the latest release. Cassava announced a $2.5 million grant in April 2020 to support the study.
The main goals are to evaluate long-term safety and tolerability of simufilam, and a secondary goal is to measure changes in cognition. The study comprises 200 patients.
“Cassava Sciences believes it is prudent to conduct an open-label study before undertaking a large, complex and expensive Phase 3 clinical program in Alzheimer’s disease: If an experimental drug for Alzheimer’s fails to show long-term safety or any treatment benefit in a large, well-designed, open-label study, such drug is unlikely to succeed under the more rigorous conditions of a randomized, controlled trial,” the statement said.
Continuing, the biotech explained that treatment effects observed in this open-label study “are not proof of drug safety or efficacy, nor can open-label data predict clinical success in a Phase 3 program.”