Belatacept, an investigational selective costimulation blocker, did not appear to be inferior to cyclosporine as a means of preventing acute rejection after renal transplantation. Belatacept may preserve the glomerular filtration rate and reduce the rate of chronic allograft nephropathy.

Natural products have long been recognized as a rich source of potent therapeutics but further development is often limited by high structural complexity and high molecular weight. In contrast, at the core of the thujaplicins is a lead-like tropolone scaffold characterized by relatively low molecular weight, ample sites for diversification, and metal-binding functionality poised for targeting a range of metalloenzyme drug targets. Here, we describe the development of this underutilized scaffold for the discovery of tropolone derivatives that function as isozyme-selective inhibitors of the validated anticancer drug target, histone deacetylase (HDAC). Several monosubstituted tropolones display remarkable levels of selectivity for HDAC2 and potently inhibit the growth of T-cell lymphocyte cell lines. The tropolones represent a new chemotype of isozyme-selective HDAC inhibitors. KEYWORDS: Tropolone, HDAC, isozyme-selectivity, thujaplicin, metalloenzyme, T-lymphocyte cancer cell lines N atural products have long served as a rich source of drugs for a variety of indications ranging from anticancer to antimicrobial to neurological disorders. Typically these natural products are characterized by high molecular weight and potency as well as high levels of structural complexity with limited sites for diversification. In contrast, thujaplicins, members of the tropolone family of natural products, can be regarded as lead-like natural products. β-Thujaplicin (also known as hinokitiol) is characterized by low molecular weight (MW = 164) and a relatively lower level of complexity that allows more extensive structural modification. Thujaplicins are monoterpene natural products isolated from the heartwood of trees in the Cupressaceae family 1 that are associated with antiproliferative activity.2−4 There have been few attempts to utilize these lead-like compounds in drug discovery, perhaps exacerbated by limited synthetic accessibility to these nonbenzenoid aromatics.The tropolone functionality is uniquely disposed to strongly chelate metal ions, which may be a hallmark of the biological activity of these compounds.3 Substituted tropolones are a compelling and distinct chemotype for the development of inhibitors of metalloenzyme drug targets. Herein, we describe our efforts to use β-thujaplicin as a lead-like natural product to develop a novel class of inhibitors of histone deacetylase, a validated target in the treatment of cancer. 5,6 Of the 18 HDAC isoforms, 11 are metalloenzymes that use zinc to remove a terminal acetyl group from lysine residues present in histones and other client proteins. The reversible acetylation and hydrolysis of the ε-acetamide in histones is associated with regulation of gene expression. Interestingly, there are a variety of natural products that inhibit HDACs such as trichostatin A (TSA; Figure 1), romidepsin, and trapoxin. Both romidepsin and vorinostat were approved by the FDA for the treatment of cutaneous T-cell lymphoma; the latter possesses a zinc-targeting hydroxamate, similar to TS...

Predictive performance of physiologically based pharmacokinetic (PBPK) and population pharmacokinetic (PopPK) models of drugs predominantly eliminated through kidney in the pediatric population was evaluated. After optimization using adult clinical data, the verified PBPK models can predict 33 of 34 drug clearance within twofold of the observed values in children 1 month and older. More specifically, 10 of 11 of predicted clearance values were within 1.5‐fold of those observed in children between 1 month and 2 years old. The PopPK approach also predicted 19 of 21 drug clearance within twofold of the observed values in children. In summary, our analysis demonstrated both PBPK and PopPK adult models, after verification with additional adult pharmacokinetic (PK) studies and incorporation of known ontogeny of renal filtration, could be applied for dosing regimen recommendation in children 1 month and older for renally eliminated drugs in a first‐in‐pediatric study.

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