Dexpramipexole (also known as KNS-760704/R-pramipexole) was originally developed by University of Virginia researchers to treat Amyotrophic Lateral Sclerosis and then was licensed to global biotechnology company Biogen Idec for further development. However, on phase III clinical trial the study of this drug was discontinued. Biogen said the drug neither slowed the loss of muscle function nor prolonged the lives of patients with ALS, often called Lou Gehrig’s disease. Nor did it show any efficacy in secondary endpoints of the clinical trial, or work in any sub-group of patients—about a big a failure as a company could have a Phase III trial. In addition, was discovered, that dexpramipexole was able to bind to beta-subunit of the mitochondrial F1/FO ATP synthase complex and increased its activity, thus reduced ischemic brain injury. These findings, together with the excellent brain penetration and favorable safety profile in humans, make dexpramipexole a drug with realistic translational potential for the treatment of stroke.

Sephin1 is a guanabenz derivative that binds to and inhibits a regulatory subunit of the stress-induced protein phosphatase 1 (PPP1R15A), but not the constitutive PPP1R15B, and lacks beta2-adrenergic activity. Phosphorylation of eIF2α, α subunit of eukaryotic translation initiation factor 2, reduces protein synthesis and prevents the accumulation of misfolded protein in the endoplasmic reticulum (ER). PPP1R15A recruits the serine/threonine-protein phosphatase PP1 to dephosphorylate eIF2α, so inhibiting PPP1R15A activity prolongs the phosphorylation of eIF2α and aids in its prevention of the accumulation of misfolded protein. In vitro, Sephin1 protected cells from lethal protein misfolding and cytotoxic ER stress. In vivo Sephin1 prevented Charcot-Marie-Tooth 1B and ALS diseases in mice.

BLZ 945, an orally active antagonist of the colony-stimulating factor1 receptor (CSF1R), is being developed by Novartis and Celgene Corporation for the treatment of advanced solid tumors and tumor-induced osteolytic lesions in bone and skeletal-related events. Phase I/II development for solid tumors is underway in the US, Italy, Spain, and Singapore. Preclinical trials were ongoing for tumor-induced osteolysis in Europe and the US. However, no recent reports of development had been identified for this indication.

Tirasemtiv is a fast skeletal troponin activator and is a candidate amyotrophic lateral sclerosis (AML) therapeutic. It is a small molecule that enhances the signals between motor neurons and neuromuscular junctions. Tirasemtiv increases muscle strength by amplifying the response of muscle when neuromuscular input is diminished secondary to a neuromuscular disease. Tirasemtiv selectively binds to the fast skeletal troponin complex, thus slowing down the rate of calcium release from troponin C and sensitizing muscle to calcium. As a consequence, the force-calcium relationship of muscle fibers shifts leftwards as does the force-frequency relationship of a nerve-muscle pair.