Istradefylline(KW-6002) (Synonyms: KW 6002)

KW-6002 is a selective adenosine A2A receptor antagonist, offering a novel mechanistic approach for the treatment of Parkinson’s disease (PD). A2A blockade will increase in GABAergic inhibition on the medium-sized neurons, leading to a net decrease in excessive activation of striatopallidal output.

In vitro: The affinity of KW-6002 for the A2AR is 70-fold greater than that for the A1 receptor. The binding affinities (Ki) of KW-6002 for human A1 receptor and A2A receptor are >287 nM and 9.12 nM, respectively [1].

In vivo: In MPTP neurotoxin model of PD in mice, KW-6002 significantly attenuated striatal dopamine depletion under various conditions. In addition, pretreatment with KW-6002 (3.3 mg/kg, i.p.) before a single dose of MPTP attenuated the partial dopamine and DOPAC depletions 1 week later [2].

Clinical trial: In a clinical study, the authors evaluated the safety and efficacy of KW-6002 40 mg as monotherapy for Parkinson’s disease (PD) in 176 patients. The primary efficacy outcome was changed from baseline to endpoint, while safe and well-tolerated, failed to show a significant improvement from placebo for this endpoint [1].

References:
[1] Park A, Stacy M.  Istradefylline for the treatment of Parkinson's disease. Expert Opin Pharmacother. 2012 Jan;13(1):111-4.
[2] Chen JF, Xu K, Petzer JP, Staal R, Xu YH, Beilstein M, Sonsalla PK, Castagnoli K, Castagnoli N Jr, Schwarzschild MA.  Neuroprotection by caffeine and A(2A) adenosine receptor inactivation in a model of Parkinson's disease. J Neurosci. 2001;21(10):RC143.