Development of small-molecule inhibitors that target PI3Kß.

Phosphatidylinositol-3 kinase (PI3K) ß, a subtype of class I PI3Ks, has an essential role in PTEN-deficient tumors and links to thrombosis, male fertility, and Fragile X syndrome. PI3Kß-specific targeting therapy could be an efficacious treatment for diseases highly dependent on PI3Kß, while mitigating the severe toxicity of pan-PI3K inhibitors. Achieving selectivity can be accomplished through three primary strategies, namely, binding to the induced lipophilic pocket, targeting the unique amino acid residue of PI3Kß, or using atropisomerism to lock conformation. In this review, we focus on advances in the development of these ß-isoform-selective PI3K inhibitors, providing potential guidance for the further development of novel clinical candidates.

Development of PI3Kγ selective inhibitors: the strategies and application.

The γ isoform of Class I PI3Ks (PI3Kγ) is primarily found in leukocytes and is essential for the function of myeloid cells, as it regulates the migration, differentiation, and activation of myeloid-lineage immune cells. Thus, PI3Kγ has been identified as a promising drug target for the treatment of inflammation, autoimmune disease, and immuno-oncology. Due to the high incidence of serious adverse events (AEs) associated with PI3K inhibitors, in the development of PI3Kγ inhibitors, isoform selectivity was deemed crucial. In this review, an overview of the development of PI3Kγ selective inhibitors in the past years is provided. The isoform selectivity of related drugs was achieved by different strategies, including inducing a specificity pocket by a propeller-shape structure, targeting steric differences in the solvent channel, and modulating the conformation of the Asp-Phe-Gly DFG motif, which have been demonstrated feasible by several successful cases. The insights in this manuscript may provide a potential direction for rational drug design and accelerate the discovery of PI3Kγ selective inhibitors.

Discovery of 4-oxo-4,5-dihydropyrazolo[1,5-a]quinoxaline-7-carboxamide derivatives as PI3Kα inhibitors via virtual screening and docking-based structure optimization.

Compound 1 with pyrazolo[1,5-a]quinoxalin-4(5H)-one scaffold was identified as a PI3Kα inhibitor hit via virtual screening strategy. Additional similarity search and molecular docking based structural modification yielded a novel series of pyrazolo[1,5-a]quinoxalin-4(5H)-one derivatives. The most potent compound 49b exhibited remarkably improved PI3Kα inhibitory activity with IC50 value of 0.24 µM and moderate to good isoform selectivity over other class I PI3K isoforms. In addition, 49b significantly inhibited the proliferation of Kasumi-1 and T47D cells with IC50 value of 1.64 and 1.82 µM, respectively. Further PK study demonstrated that it has favorable pharmacokinetic profiles (AUC0-t = 3294.05 ng·h/mL at 5.0 mg/kg PO, F = 91.8%). All these data indicated that compound 49b was a promising PI3Kα inhibitor with beneficial drug-like properties and merited further development.

Advances in the Discovery of Novel Inhaled PI3Kδ Inhibitors for the Treatment of Asthma.

Bronchial asthma is the most common chronic respiratory illness, the incidence of which continues to increase annually. Currently, effective treatments for CS-resistant asthma and severe asthma are still lacking, and new therapeutic regimens are urgently required. PI3Kδ is a key enzyme in hematopoietic cells and represents a major target for oncology and inflammatory disease (particularly respiratory disease, asthma and COPD). In the case of respiratory disease, the ability to inhibit PI3Kδ in the lungs shows a higher safety and therapeutic index relative to systemic inhibition. In recent years, paradigm shifts have occurred in inhalation therapeutics for systemic and topical drug delivery due to the favorable properties of lungs, including their large surface area and high permeability. Pulmonary drug delivery possesses many advantages, including a non-invasive route of administration, low metabolic activity, a controlled environment for systemic absorption and the ability to avoid first bypassing metabolism. In this review, we focus on the discovery and development of inhaled drugs targeting PI3Kδ for asthma by focusing on their activity and selectivity, in addition to their potential in drug design strategies using inhaled administration.

Discovery of 2-(5-(quinolin-6-yl)-1,3,4-oxadiazol-2-yl)acetamide derivatives as novel PI3Kα inhibitors via docking-based virtual screening.

PI3Kα is an attractive target for PIK3CA mutated malignant tumor and searching for lead compounds with novel scaffold is important for the development of PI3Kα inhibitors. Therefore, the strategy of docking-based virtual screening was performed to discovery potent inhibitors. The 4L2Y_A PI3Kα crystal structure was used as the model protein receptor due to its high docking reliability. After the multistep virtual screening protocol and biological evaluation, three hits were picked up and further similarity searching led to more potent 2-(5-(quinolin-6-yl)-1,3,4-oxadiazol-2-yl)acetamide derivatives ES-25 and ES-27. In addition, the primary SAR of these novel derivatives was discussed, which provide a basis for the further structural modification.

Design, synthesis and biological evaluation of novel benzothiadiazine derivatives as potent PI3Kδ-selective inhibitors for treating B-cell-mediated malignancies.

A series of 24 benzothiadiazine derivatives with structural novelty were designed, synthesized and biologically evaluated as PI3Kδ-selective inhibitors. As a consequence of the structure-activity relationship (SAR) study, compounds 63 and 71 were identified with single-digit nanomolar IC50 values against PI3Kδ and submicromolar GI50 values against human malignant B-cell line SU-DHL-6. Furthermore, chiral resolution of the key amine intermediate of these two compounds was performed to achieve corresponding enantiomers. In subsequent biological evaluation, S-63 (IC50: 4.6 nM) and S-71 (IC50: below 0.32 nM) demonstrated comparable and superior PI3Kδ inhibitory activity, respectively, to that of idelalisib. Additionally, both S-63 (GI50: 33.2 nM) and S-71 (GI50: 15.9 nM) exerted enhanced anti-proliferative activity against the SU-DHL-6 cell line than that of idelalisib. Moreover, both S-63 and S-71 exhibited excellent PI3Kδ selectivity. In the further in vivo pharmacokinetic (PK) study, S-63 displayed a good plasma exposure and an acceptable oral bioavailability of 29.2%. By virtue of its biological performance, S-63 merits further development as a potential therapeutic agent for battling B-cell-mediated malignancies.

Bio-Electron-Fenton (BEF) process driven by microbial fuel cells for triphenyltin chloride (TPTC) degradation.

The intensive use of triphenyltin chloride (TPTC) has caused serious environmental pollution. In this study, an effective method for TPTC degradation was proposed based on the Bio-Electron-Fenton process in microbial fuel cells (MFCs). The maximum voltage of the MFC with graphite felt as electrode was 278.47% higher than that of carbon cloth. The electricity generated by MFC can be used for in situ generation of H2O2 to a maximum of 135.96µmolL-1 at the Fe@Fe2O3(*)/graphite felt composite cathode, which further reacted with leached Fe2+ to produce hydroxyl radicals. While 100µmolL-1 TPTC was added to the cathodic chamber, the degradation efficiency of TPTC reached 78.32±2.07%, with a rate of 0.775±0.021µmolL-1h-1. This Bio-Electron-Fenton driving TPTC degradation might involve in SnC bonds breaking and the main process is probably a stepwise dephenylation until the formation of inorganic tin and CO2. This study provides an energy saving and efficient approach for TPTC degradation.