Parkinson's disease (PD) is a debilitating neurodegenerative disorder characterized mainly by the progressive loss of dopaminergic neurons in the substantia nigra pars compacta (SNpc), resulting in severe neurological deficits. The existing approaches to PD treatment are focused mainly on alleviating motor symptoms by compensating for neurochemical deficits, but such treatment fails to halt progression of the neurodegenerative process. The lack of effective neuroprotective drugs for PD is primarily attributed to a limited understanding of the complex mechanisms involved in the degenerative processes of the nigral dopaminergic system. However, recent discoveries about cell death pathways and oxidative stress signaling have offered some important clues that boost hope for the development of novel mechanism-based neuroprotective strategies for PD. In this regard, we have demonstrated that oxidative stress triggers the mitochondrially mediated caspase cascade and Fyn kinase activation to induce neuronal cell death1-3,17-20 cell culture and animal models of neurodegeneration. Furthermore, Fyn knockout mice are resistant to MPTP-induced behavioral deficits, neurochemical depletion, and nigral dopaminergic neuronal damage. Very recently, we observed that Fyn kinase is rapidly activated and mediates LPS- and ?SynPFF-induced increases in nitrite and proinflammatory cytokine production in cell culture and animal models of neuroinflammation. Collectively, these mechanistic studies reveal that Fyn is a key upstream proapoptotic kinase involved in neuroinflammation, and as such, it could prove to be a promising therapeutic target for PD. Importantly, we screened >300 compounds from the focused kinase CP library belonging to 10 different scaffolds against human Fyn kinase. This resulted in identification of nine compounds with >90% inhibition of human Fyn kinase activity. The best among these, CP14028 and CP15078 belonging to 3 different scaffolds, exhibited an IC50 of 190-262 nM for human Fyn inhibition. A dose-response study revealed that CP analogs inhibited LPS- and ?SynPFF-induced increases in nitrite (IC50 range 0.1-1.5 M) and proinflammatory cytokine production, unlike the AZD0530 Fyn kinase inhibitor, which in clinical trials failed to inhibit even at 30 M. To capitalize on these discoveries and to demonstrate proof-of-principle, we are proposing PK, CNS bioavailability, metabolic stability and preclinical efficacy studies of CP14028 and CP15078 in this SBIR P1 exploratory application prior to developing CP analogs with an exceptionally low, nanomolar IC50 for Fyn, as well as preclinical toxicology and safety studies. The combination of a validated therapeutic target, integrated study design and demonstrated expertise will help us accomplish these important goals. We anticipate that these CP analogs would advance to pharma fingerprint, HERG, CYP, dose-formulations, preclinical toxicological and safety evaluations in SBIR PII grant applications. The overall approach is expected to result in a new class of disease-modifying drugs for PD. A joint WTO patent application between ChemVeda and PK Biosciences has been filed No. 20170106006.
Existing therapies to treat neurodegenerative diseases, such as Parkinson's disease (PD), focus mainly on treating symptoms rather than halting disease progression. Recent mechanistic studies indicate that Fyn kinase activation contributes to neurodegenerative processes in PD. Thus, in this proof-of-concept study, we will validate tri-heterocyclic small-molecule inhibitors of Fyn kinase as novel anti-neuroinflammatory agents for treating neurodegenerative disorders.
