- German drugmaker Boehringer Ingelheim International GmbH will shutter further development of its experimental PDE9 inhibitor in Alzheimer's disease, opting to focus its resources elsewhere after the candidate failed in Phase 2 clinical studies.
- Boehringer's candidate, known as BI 409306, did not improve cognitive impairment in Alzheimer's patients when compared to placebo, according to topline results released by the drugmaker on Feb. 9.
- Research efforts will now shift to focus on trials congoing in schizophrenia, where Boehringer hopes blocking the PDE9A protein can improve signaling in the glutamatergic circuit of the brain.
Boehringer's candidate wasn't as closely tracked as other experimental Alzheimer's drugs moving through pharma pipelines. Even so, its failure to show any cognitive benefit adds to the ever-lengthening list of setbacks for research into the memory-robbing neurodegenerative disease.
Unlike most drugs under investigation in the space, BI 409306 is designed to improve signaling in the brain rather than clearing amyloid plaques or clumps of tau protein. The drug blocks PDE9A in an attempt to restore function to the glutamergic brain circuit, which involves the neurotransmitter glutamate.
Boehringer enrolled 457 patients across two Phase 2 studies of BI 409306, testing the drug against placebo over 12 weeks. Topline data, however, showed no benefit versus placebo, prompting Boehringer's decision to pull support.
"This is what research is about: disappointments are a daily experience in science, but even these clinical trial results will add to the understanding of brain function and contribute to future progress in this area," said Jan Poth, head of CNS and immunology at Boehringer, in a Feb. 9 statement.
Research will continue in schizophrenia. Two studies testing BI 409306's effect on relapse prevention and prevention of first episode psychosis remain ongoing.
Boehringer also plans to test a compound aimed at inhibiting GlyT1 in a "range of central nervous system indications which also include Alzheimer's disease."