Design of BET Inhibitor Prodrugs with Superior Efficacy and Devoid of Systemic Toxicities

<div><p>Prodrugs engineered for preferential activation in diseased versus normal tissues offer immense potential to improve the therapeutic index of preclinical and clinical-stage active pharmaceutical ingredients that either cannot be developed otherwise or whose efficacy or tolerability it is highly desirable to improve. Such approaches, however, often suffer from trial-and-error design, precluding predictive design and optimization. Here, using BET bromodomain inhibitors (BETi)—a class of epigenetic regulators with proven anti-cancer activity but clinical development hindered by systemic adverse effects–– we introduce a platform that overcomes these challenges. Through tuning of traceless linkers appended to a “brush prodrug” scaffold, we demonstrate that it is possible to correlate <i>in vitro </i>prodrug activation kinetics with <i>in vivo </i>tumor pharmacokinetics, leading to novel BETi prodrugs with enhanced anti-tumor efficacy and devoid of dose-limiting toxicities. This work has immediate clinical implications, introducing principles for the predictive design of prodrugs and potentially overcoming hurdles in drug development. </p></div>

Design of BET Inhibitor Prodrugs with Superior Efficacy and Devoid of Systemic Toxicities

<div><p>Prodrugs engineered for preferential activation in diseased versus normal tissues offer immense potential to improve the therapeutic index of preclinical and clinical-stage active pharmaceutical ingredients that either cannot be developed otherwise or whose efficacy or tolerability it is highly desirable to improve. Such approaches, however, often suffer from trial-and-error design, precluding predictive design and optimization. Here, using BET bromodomain inhibitors (BETi)—a class of epigenetic regulators with proven anti-cancer activity but clinical development hindered by systemic adverse effects–– we introduce a platform that overcomes these challenges. Through tuning of traceless linkers appended to a “brush prodrug” scaffold, we demonstrate that it is possible to correlate <i>in vitro </i>prodrug activation kinetics with <i>in vivo </i>tumor pharmacokinetics, leading to novel BETi prodrugs with enhanced anti-tumor efficacy and devoid of dose-limiting toxicities. This work has immediate clinical implications, introducing principles for the predictive design of prodrugs and potentially overcoming hurdles in drug development. </p></div>

The Unique Pharmacometrics of Small Molecule Therapeutic Drug Tracer Imaging for Clinical Oncology

Translational development of radiolabeled analogues or isotopologues of small molecule therapeutic drugs as clinical imaging biomarkers for optimizing patient outcomes in targeted cancer therapy aims to address an urgent and recurring clinical need in therapeutic cancer drug development: drug- and target-specific biomarker assays that can optimize patient selection, dosing strategy, and response assessment. Imaging the in vivo tumor pharmacokinetics and biomolecular pharmacodynamics of small molecule cancer drugs offers patient- and tumor-specific data which are not available from other pharmacometric modalities. This review article examines clinical research with a growing pharmacopoeia of investigational small molecule cancer drug tracers.

Impact of soft protein interactions on the excretion, extent of receptor occupancy and tumor accumulation of ultrasmall metal nanoparticles: a compartmental model simulation

A compartmental model simulation shows that the blood and tumor pharmacokinetics of ultrasmall metal nanoparticles can be modulated by soft interactions with plasma proteins.