E pyrrolidine ring in protic solution, giving rise to unique stereoisomers with unique binding Bensulfuron-methyl manufacturer affinities to MDM2 [97]. Consequently, in 2015, a second generation of spirooxindoles emerged that possess symmetrical substituents at C21 position in the pyrrolidine ring that enable a rapid and irreversible conversion towards the most active diastereoisomer (MI-1061: 29, FP Ki = 0.16 nM, WST-8 SJSA-1 IC50 = 0.10 ) [98]. Compounds 27 and 28 in the first generation had been already synthesized having in consideration the desired stereochemistry. Interestingly the most effective diastereomer revealed a different and greater binding to MDM2 using the neopentyl and phenyl ring occupying now Phe19(p53) and Leu26(p53) pockets respectively (Figure 8, represented for compound 26). In addition their side chain carbonyl is NI-42 In Vivo capable of establishing a H bond with all the imidazole side chain of His96 along with the terminal hydroxyl group with the Lys94 side chain [96]. Compound 28 advanced into clinical trials in 2012 sponsored by Sanofi. It displays a lot more than 100-fold selectivity more than cell lines with mutated or deleted p53, activating a p53-dependent pathway major to cell-cycle arrest and/or apoptosis in cancer cells in vitro and in vivo xenograft tumor models.Pharmaceuticals 2016, 9, 25 Pharmaceuticals 2016, 9,11 of 33 11 ofmodels. A complete tumor was achieved accomplished at having a every day dose for 9 dose for at 200 and at A total tumor regressionregression wasat one hundred mg/kg100 mg/kg using a day-to-day days and9 days mg/kg 200 mg/kg with single SJSA-1 mice xenograft [96]. having a single oraladose in oral dose in SJSA-1 mice xenograft [96].Figure 8.8. Spiropyrrolidine scaffold optimization. Docking posecompound 28 in28 in MDM2 3LBL). Figure Spiropyrrolidine scaffold optimization. Docking pose of of compound MDM2 (PDB (PDB MDM2 surface issurface is colored in blue for hydrophilic areas and grey for locations. Compound 28 3LBL). MDM2 colored in blue for hydrophilic areas and grey for hydrophobic hydrophobic areas. isCompound 28 is depictedandstick modelaccording to element kind: white for variety: white for blue for depicted in stick model in is colored and is colored according to element carbon atoms, carbon nitrogenblue forred for oxygen atoms, bright green for fluorine, and dark green for chlorinegreen for atoms, atoms, nitrogen atoms, red for oxygen atoms, bright green for fluorine, and dark atoms.chlorine atoms.Pharmaceuticals 2016, 9,Pharmaceuticals 2016, 9,12 of12 ofIn 2014, Hoffmann-La Roche published two other papers describing further optimizations ofof other papers describing further optimizations In 2014, Hoffmann-La Roche published spiro[oxindole-3,31 -pyrrolidines], having in consideration the useful PK and potency improvement spiro[oxindole-3,3-pyrrolidines], having in consideration the valuable PK and potency obtained whenobtained when a phenyl derivative groupto the amide side amide side chain. RO8994 improvement a phenyl derivative group is attached is attached for the chain. RO8994 (30, HTRF IC50 = 5 nM,IC50 = 5 nM, SJSA-1 IC50 = 13 nM,emerged inside a SAR study focused especiallyespecially in (30, HTRF SJSA-1 IC50 = 13 nM, Figure 9) Figure 9) emerged inside a SAR study focused in additional further modifications chain [99,100]. [99,100]. Bioisosteric substitution on the 6-chlorooxindole modifications to this sideto this side chain Bioisosteric substitution from the 6-chlorooxindole moiety moiety led to compounds RO2468 (31, IC50 IC50 = 6 nM, MTT SJSA-1 IC = 3 nM), and RO5353 (32.
