Design, Synthesis, and Structure–Activity Relationship Optimization of Pyrazolopyrimidine Amide Inhibitors of Phosphoinositide 3-Kinase γ (PI3Kγ)

Abstract

Phosphoinositide-3-kinase γ (PI3Kγ) is highly expressed in immune cells and promotes the production and migration of inflammatory mediators. The inhibition of PI3Kγ has been shown to repolarize the tumor immune microenvironment to a more inflammatory phenotype, thereby controlling immune suppression in cancer. Herein, we report the structure-based optimization of an early lead series of pyrazolopyrimidine isoindolinones, which culminated in the discovery of highly potent and isoform-selective PI3Kγ inhibitors with favorable drug-like properties. X-ray cocrystal structure analysis, molecular docking studies, and detailed structure−activity relationship investigations resulted in the identification of the optimal amide and isoindolinone substituents to achieve a desirable combination of potency, selectivity, and metabolic stability. Preliminary in vitro studies indicate that inhibition of PI3Kγ with compound 56 results in a significant immune response by increasing pro-inflammatory cytokine gene expression in M1 macrophages.

Development of a Robust and Scalable Synthetic Route for a Potent and Selective Isoindolinone PI3Kγ Inhibitor

“…The unoptimized discovery synthesis of 1 and related compounds employed a modular approach that allowed diversification of each fragment to facilitate SAR studies . From a process chemistry perspective, this approach was expected to be amenable to scale-up since two points of convergence are present.…”

“…Previously, we launched a program to develop a potentially best-in-class PI3Kγ inhibitor, which culminated in the discovery of 1 (Figure ). Compound 1 exhibited excellent in vitro PI3Kγ activity, high isoform selectivity, and favorable drug metabolism and pharmacokinetic (DMPK) properties, which warranted further preclinical characterization. To supply material for additional preclinical characterization (e.g., in vivo efficacy studies, safety/toxicology, and solid form analysis), a highly efficient and scalable synthesis of 1 was required.…”

Targeting the PI3K/AKT/mTOR Signaling Pathway in the Treatment of Human Diseases: Current Status, Trends, and Solutions

“…Compound 50 showed excellent drug-like properties such as high metabolic stability, exposure, oral bioavailability, and safety profile in four preclinical species (mice, rats, dogs, and cynomolgus monkeys). Furthermore, compound 50 could exert a pro-inflammatory effect by upregulating the gene expression of pro-inflammatory cytokines in interferon gamma- and lipopolysaccharide-stimulated M1 macrophages …”

“…Furthermore, compound 50 could exert a pro-inflammatory effect by upregulating the gene expression of pro-inflammatory cytokines in interferon gammaand lipopolysaccharide-stimulated M1 macrophages. 139 5.2. AKT Inhibitors.…”

Direct Bioisostere Replacement Enabled by Metallaphotoredox Deoxydifluoromethylation

“…Consequently, their applicability is highly situational and difficult to predict a priori. In contrast, the bioisosteric difluoromethyl group retains the ability to participate in hydrogen-bonding interactions yet is significantly more lipophilic, metabolically stable, and chemically inert. − To date, the difluoromethyl group has been most commonly explored in the form of X–CF 2 H − and C­(sp 2 )–CF 2 H , groups. Notably, although sp 3 -enriched drug candidates tend to exhibit improved pharmacological properties with higher clinical success rates, the incorporation of C­(sp 3 )–CF 2 H groups into pharmaceutical candidates remains conspicuously underexplored.…”