Structure-based discovery and bio-evaluation of a cyclopenta[4,5]thieno[2,3-d]pyrimidin-4-one as a phosphodiesterase 10A inhibitor

Phosphodiesterase10A (PDE10A) is a potential therapeutic target for the treatment of several neurodegenerative disorders.

“Restlessness” After Cancer Diagnosis and Treatment

A 76-year-old woman sought care for unintentional weight loss, hematuria, and fatigue. She was diagnosed with plurimetastatic renal cell carcinoma. After resection of the primary tumor and metastases, she was treated with pembrolizumab, an immune checkpoint inhibitor. The patient experienced involuntary tongue and face movements with dysphagia and weight loss. She was also described as “restless.” At that point, the patient was in cancer remission with ongoing immune checkpoint inhibitor treatment. Blood testing was unremarkable. Brain magnetic resonance imaging showed basal ganglia T2/fluid-attenuated inversion recovery hyperintensities without gadolinium enhancement. Cerebrospinal fluid testing showed slightly increased protein concentration and 8 cerebrospinal fluid-restricted oligoclonal bands. Serum and cerebrospinal fluid testing for neural autoantibodies showed immunoglobulin G immunoreactivity in a mouse tissue indirect immunofluorescence assay, predominantly staining the basal ganglia. The immunoglobulin G was subsequently identified to bind to phosphodiesterase 10A. The patient was diagnosed with paraneoplastic phosphodiesterase 10A-immunoglobulin G autoimmunity manifesting as hyperkinetic movement disorder triggered by immune checkpoint inhibitor treatment. Given the patient’s cancer remission, the immune checkpoint inhibitor treatment was discontinued. She was treated with high-dose intravenous corticosteroids, with improvement of her hyperkinetic movement disorder but persistence of some dystonic movements. Further treatment with oral prednisone did not produce further improvement. The patient was treated symptomatically with onabotulinumtoxinA injections and tetrabenazine, which ameliorated her dystonic movements. Three years after her cancer diagnosis, she was alive and in cancer remission with minimal residual movements. Immune checkpoint inhibitors are monoclonal antibodies targeting “stop signs” of the immune response, which lead to enhanced endogenous responses, including those against cancer. Autoimmune complications are consequences of the enhanced immunity and can affect all organs, including the nervous system.

Phosphodiesterase 10A is a critical target for neuroprotection in a mouse model of ischemic stroke

Phosphodiesterase 10A (PDE10A) hydrolyzes adenosine 3′,5′-cyclic monophosphate (cAMP) and guanosine 3′,5′-cyclic monophosphate (cGMP). It is highly expressed in the striatum. Recent evidence implied that PDE10A may be involved in the inflammatory processes following injury, such as ischemic stroke. Its role in ischemic injury was unknown. Herein, we exposed mice to 90 or 30 min middle cerebral artery occlusion, followed by the delivery of the highly selective PDE10A inhibitor TAK-063 (0.3 mg/kg or 3 mg/kg) immediately after reperfusion. Animals were sacrificed after 24 or 72 hours, respectively. Both TAK-063 doses enhanced neurological function, reduced infarct volume, increased neuronal survival, reduced brain edema, and increased blood-brain barrier integrity, alongside cerebral microcirculation improvements. Post-ischemic neuroprotection was associated with increased phosphorylation (i.e., activation) of pro-survival Akt, Erk-1/2 and GSK-3α/β, decreased phosphorylation (i.e., activation) of pro-survival mTOR, increased HIF-1α, MMP-9 and anti-apoptotic Bcl-xL abundance, and reduced pro-apoptotic Bax abundance. Interestingly, PDE10A inhibition reduced inflammatory cytokines/chemokines, including IFN-γ and TNF-α, analyzed by planar surface immunoassay. In addition, liquid chromatography-tandem mass spectrometry revealed 40 proteins were significantly altered by TAK-063. Our study established PDE10A as a target for ischemic stroke therapy.

Phosphodiesterase 10A is a critical target for neuroprotection in a mouse model of ischemic stroke

Phosphodiesterase 10A (PDE10A) hydrolyzes adenosine 3′,5′-cyclic monophosphate (cAMP) and guanosine 3′,5′-cyclic monophosphate (cGMP). It is highly expressed in the striatum. Recent evidence implied that PDE10A may be involved in the inflammatory processes following injury, such as ischemic stroke. Its role in ischemic injury was unknown. Herein, we exposed mice to 90 or 30 min middle cerebral artery occlusion, followed by the delivery of the highly selective PDE10A inhibitor TAK-063 (0.3 mg/kg or 3 mg/kg) immediately after reperfusion. Animals were sacrificed after 24 or 72 hours, respectively. Both TAK-063 doses enhanced neurological function, reduced infarct volume, increased neuronal survival, reduced brain edema, and increased blood-brain barrier integrity, alongside cerebral microcirculation improvements. Post-ischemic neuroprotection was associated with increased phosphorylation (i.e., activation) of pro-survival Akt, Erk-1/2 and GSK-3α/β, decreased phosphorylation (i.e., activation) of pro-survival mTOR, increased HIF-1α, MMP-9 and anti-apoptotic Bcl-xL abundance, and reduced pro-apoptotic Bax abundance. Interestingly, PDE10A inhibition reduced inflammatory cytokines/chemokines, including IFN-γ and TNF-α, analyzed by planar surface immunoassay. In addition, liquid chromatography-tandem mass spectrometry revealed 40 proteins were significantly altered by TAK-063. Our study established PDE10A as a target for ischemic stroke therapy.