GSK3494245 (DDD01305143) is a potent, orally active, and selective inhibitor of the chymotrypsin-like activity of the parasite proteasome binding in a site sandwiched between the β4 and β5 subunits (IC50=0.16 μM for WT L. donovani proteasomes). GSK3494245 moderately inhibits chymotrypsin-like activity of human proteasome (IC50: purified 26S=13 µM; enriched THP-1 extracts IC50=40µM). GSK3494245 exhibits attractive biological and biosafety properties[1][2].
GSK3494245 shows EC50 value of 5.7 μM in L. donovani intramacrophage assay, where the amastigotes are cultured in differentiated THP-1 cells. GSK3494245 demonstrates good selectivity over mammalian cell growth inhibition (THP-1 cells; EC50 > 50 μM)[1].GSK3494245 (DDD01305143) shows pEC50s of 6.5 and 5.8 against axenic amastigote and ld InMac, respectively. Ld InMac is the intramacrophage assay carried out in THP-1 cells with L. donovani amastigote[2].
GSK3494245 (25 mg/kg; orally twice a day for 10 consecutive days) elicits a >95% reduction of parasite load in Infected mice (L. donovani, LV9)[1].
[1]. Wyllie S, et al. Preclinical candidate for the treatment of visceral leishmaniasis that acts through proteasome inhibition. Proc Natl Acad Sci U S A. 2019;116(19):9318-9323. [2]. Thomas MG, et al. Identification of GSK3186899/DDD853651 as a Preclinical Development Candidate for the Treatment of Visceral Leishmaniasis. J Med Chem. 2019;62(3):1180-1202.