Design, Synthesis, and Evaluation of Niclosamide Analogs as Therapeutic Agents for Enzalutamide-Resistant Prostate Cancer.

Niclosamide effectively downregulates androgen receptor variants (AR-Vs) for treating enzalutamide and abiraterone-resistant prostate cancer. However, the poor pharmaceutical properties of niclosamide due to its solubility and metabolic instability have limited its clinical utility as a systemic treatment for cancer. A novel series of niclosamide analogs was prepared to systematically explore the structure-activity relationship and identify active AR-Vs inhibitors with improved pharmaceutical properties based on the backbone chemical structure of niclosamide. Compounds were characterized using 1H NMR, 13C NMR, MS, and elemental analysis. The synthesized compounds were evaluated for antiproliferative activity and downregulation of AR and AR-V7 in two enzalutamide-resistant cell lines, LNCaP95 and 22RV1. Several of the niclosamide analogs exhibited equivalent or improved anti-proliferation effects in LNCaP95 and 22RV1 cell lines (B9, IC50 LNCaP95 and 22RV1 = 0.130 and 0.0997 µM, respectively), potent AR-V7 down-regulating activity, and improved metabolic stability. In addition, both a traditional structure-activity relationship (SAR) and 3D-QSAR analysis were performed to guide further structural optimization. The presence of two -CF3 groups of the most active B9 in the sterically favorable field and the presence of the -CN group of the least active B7 in the sterically unfavorable field seem to make B9 more potent than B7 in the antiproliferative activity.

Design and synthesis of a novel ZB716-d6 as a stable isotopically labeled internal standard.

ZB716 is a synthetic, steroidal, orally active anti-estrogen agent that is under clinical development for the treatment of estrogen receptor (ER)-positive metastatic breast cancer. The stable isotope-labeled ZB716 was required for use as an internal standard in LC-MS/MS assays. Therefore, a novel deuterated ZB716 (ZB716-d6) as an isotopically labeled internal standard was designed and synthesized through a newly developed route, which prepared ZB716-d6 in eight steps from the commercially available deuterium-labeled starting material [2H6]pentafluoropentanol. This procedure is very practicable and gives the final compound in good yield (19% total yield) and high purity (D, >99%, chemical purity 98%). At present, ZB716-d6 has been successfully used as an internal standard in clinical bioanalysis.

Fulvestrant-3-Boronic Acid (ZB716) Demonstrates Oral Bioavailability and Favorable Pharmacokinetic Profile in Preclinical ADME Studies.

Fulvestrant-3-boronic acid (ZB716), an oral selective estrogen receptor degrader (SERD) under clinical development, has been investigated in ADME studies to characterize its absorption, metabolism, and pharmacokinetics. ZB716 was found to have high plasma protein binding in human and animal plasma, and low intestinal mucosal permeability. ZB716 had high clearance in hepatocytes of all species tested. ZB716 was metabolized primarily by CYP2D6 and CYP3A. In human liver microsomes, ZB716 demonstrated relatively low inhibition of CYP1A2, 2C8, 2C9, 2C19, 2D6, and 3A4 (when testosterone was used as the substrate), and no inhibition of CYP2B6 and 3A4 (when midazolam was used as the substrate). In assays for enzyme activity, ZB716 induced CYP1A2, 2B6, and 3A4 in a concentration-dependent manner. Single-dose and repeated-dose pharmacokinetic studies in rats and dogs showed oral bioavailability, dose-proportional drug exposure, and drug accumulation as measured by maximum concentration and area under the concentration-time curve (AUC).

From Pure Antagonists to Pure Degraders of the Estrogen Receptor: Evolving Strategies for the Same Target.

Pure antiestrogens, or selective estrogen receptor degraders (SERDs), have proven to be effective in treating breast cancer that has progressed on tamoxifen and/or aromatase inhibitors. However, the only FDA-approved pure antiestrogen, fulvestrant, is limited in efficacy by its low bioavailability. The search for orally bioavailable SERDs has continued for nearly as long as the clinical history of the injection-only fulvestrant. Oral SERDs that have been developed and tested in patients ranged from nonsteroidal ER binders containing an acrylic acid or amino side chain to bifunctional proteolysis-targeting chimera (PROTAC) pure ER degraders. Structural evolution in the development of oral SERD molecules has been closely associated with quantifiable ER-degrading potency, as seen in the structural comparison analysis of acrylic acid and basic amino side-chain-bearing SERDs. Failure to improve on fulvestrant in the clinical trials by numerous acidic SERDs and early basic SERDs is blamed on tolerability and/or insufficient efficacy, which will likely be overcome by the new-generation basic SERD molecules and PROTAC ER degraders with improved oral bioavailability, low toxicity, and superior efficacy of receptor degradation.

Discovery of novel 2-benzylisoquinolin-1(2H)-ones as potent vasodilative agents.

2-Benzylisoquinolin-1(2H)-ones has been proposed as vasodilative agents on the basis of scaffold hopping. In the present study, a series of 2-benzylisoquinolin-1(2H)-ones were synthesized. Their vasodilative effects were evaluated by wire myograph on isolated rat mesenteric arterial ring induced contraction with 60mM KCl. The structure-activity relationships of target compounds were discussed. Among these compounds, C7 and C8 displayed potent vasodilative effects and significantly inhibited the contraction of rat mesenteric arterial rings induced by phenylephrine. The antihypertensive effects of compounds C7 and C8 on SHR were further evaluated. The results indicated that oral administrational C7 and C8 can significantly reduce both diastolic and systolic blood pressure in a dose-dependent manner. Moreover, C7 maintained the effects for 4h at a dosage of 4.0mg/kg. These findings suggest that the title compounds can serve as novel vasodilative agents and promising antihypertensive agents.

Synthesis and antitumor activities evaluation of m-(4-morpholinoquinazolin-2-yl)benzamides in vitro and in vivo.

In the present study, a series of m-(4-morpholinoquinazolin-2-yl)benzamides were designed, synthesized and characterized. The antiproliferative activities of the synthesized compounds were evaluated against two human cell lines (HCT-116 and MCF-7). Compounds with IC50 values below 4 µM were further evaluated against U-87 MG and A549 cell lines. Among these evaluated compounds, compound T10 displayed a remarkable antiproliferative effect in vitro. The hoechst staining assay showed that compound T10 caused morphological changes. The cell cycle and apoptosis assay further indicated that compound T10 can arrest HCT-116 cells in G2/M and G0/G1 phase and induce apoptosis. PI3K enzyme assays indicated that compounds T7 and T10 selectively inhibit PI3Kα. A Western bolt assay further suggested that compound T10 can block the PI3K/Akt/mTOR pathway. Moreover, compound T10 inhibited tumor growth on a mice S180 homograft model. These findings directly identify m-(4-morpholinoquinazolin-2-yl)benzamide derivatives as novel anticancer agents.

Discovery of 2-aryl-8-hydroxy (or methoxy)-isoquinolin-1(2H)-ones as novel EGFR inhibitor by scaffold hopping.

2-Aryl-8-hydroxy (or methoxy)-isoquinolin-1(2H)-one has been proposed as a novel scaffold of EGFR inhibitor based on scaffold hoping. In the present study, a series of 2-aryl-8-hydroxy (or methoxy)-isoquinolin-1(2H)-one derivatives were synthesized. Their antiproliferative activities in vitro were evaluated via MTT assay against two human cancer cell lines, including A431 and A549. The SAR of the title compounds was preliminarily discussed. The compounds with ideal inhibition were evaluated through ELISA-based EGFR-TK assay. Compound 6c showed the best activity against A431 and EGFR tyrosine kinase. These findings suggest that title compounds are EGFR inhibitors with novel structures.