Macrocyclic Prodrugs of a Selective Nonpeptidic Direct Thrombin Inhibitor Display High Permeability, Efficient Bioconversion but Low Bioavailability

Prodrugs as empowering tools in drug discovery and development: recent strategic applications of drug delivery solutions to mitigate challenges associated with lead compounds and drug candidates

The delivery of a drug to a specific organ or tissue at an efficacious concentration is the pharmacokinetic (PK) hallmark of promoting effective pharmacological action at a target site with an acceptable safety profile. Sub-optimal pharmaceutical or ADME profiles of drug candidates, which can often be a function of inherently poor physicochemical properties, pose significant challenges to drug discovery and development teams and may contribute to high compound attrition rates. Medicinal chemists have exploited prodrugs as an informed strategy to productively enhance the profiles of new chemical entities by optimizing the physicochemical, biopharmaceutical, and pharmacokinetic properties as well as selectively delivering a molecule to the site of action as a means of addressing a range of limitations. While discovery scientists have traditionally employed prodrugs to improve solubility and membrane permeability, the growing sophistication of prodrug technologies has enabled a significant expansion of their scope and applications as an empowering tool to mitigate a broad range of drug delivery challenges. Prodrugs have emerged as successful solutions to resolve non-linear exposure, inadequate exposure to support toxicological studies, pH-dependent absorption, high pill burden, formulation challenges, lack of feasibility of developing solid and liquid dosage forms, first-pass metabolism, high dosing frequency translating to reduced patient compliance and poor site-specific drug delivery. During the period 2012-2022, the US Food and Drug Administration (FDA) approved 50 prodrugs, which amounts to 13% of approved small molecule drugs, reflecting both the importance and success of implementing prodrug approaches in the pursuit of developing safe and effective drugs to address unmet medical needs.

Current screening, design, and delivery approaches to address low permeability of chemically synthesized modalities in drug discovery and early clinical development

A drug's permeability across biological membranes is a key property associated with the successful development of an orally absorbed drug candidate. Although a variety of methods are available for predicting and assessing permeability, some are more preferred than others at specific stages of drug discovery and development across the pharmaceutical industry. Permeability measurements may be interpreted differently depending on the chosen method. Herein, we present a refreshed perspective on the screening approaches and philosophy in permeability evaluation, from early drug discovery to early clinical development. Additionally, we review and discuss chemical design and drug delivery technologies that can be leveraged to overcome permeability challenges, which are increasingly being used with emerging modalities.

Direct Oral Anticoagulants Combined with Antiplatelet Therapy in the Treatment of Coronary Heart Disease: An Updated Meta-analysis

BACKGROUND

Direct oral anticoagulants (DOACs) combined with antiplatelet therapy for acute coronary syndrome (ACS) may reduce ischemic events, but there is no consensus on bleeding risk. Moreover, the effect of DOACs on stable coronary artery disease (CAD) needs to be elucidated. We conducted a meta-analysis to summarize the efficacy and safety of DOACs combined with antiplatelet therapy in the treatment of stable CAD and ACS.

METHODS

We searched PubMed, Web of Science, and the Cochrane Central Register of Controlled Trials, then performed a systematic review of all 17 randomized controlled trials.

RESULTS

For patients with stable CAD, DOACs combined with antiplatelet therapy significantly reduced the rate of major adverse cardiovascular events (MACE) (risk ratio; 95% confidence interval: 0.88; 0.81-0.95) and ischemic stroke (0.62; 0.50-0.77), with a relatively low risk of major bleeding (1.72; 1.42-2.07). For patients with ACS, the combination of DOACs reduced the risk of MACE (0.91; 0.85-0.97), myocardial infarction (MI) (0.90; 0.83-0.98), and ischemic stroke (0.75; 0.58-0.97), accompanied by increased non-fatal bleeding events and intracranial hemorrhage (3.42; 1.76-6.65). Results were similar when restricting the analysis to phase III studies except for the rate of stroke in patients with ACS.

CONCLUSIONS

Combination therapy reduced the incidence of MI in ACS patients, but the risk of bleeding from intracranial hemorrhaging outweighs the benefit of MACE driven by MI. That is due to combination therapy having no positive impact on mortality; thus, the benefit-risk balance may be more favorable  in patients with stable CAD.

Structure-based development of new RAS-effector inhibitors from a combination of active and inactive RAS-binding compounds

The RAS gene family is frequently mutated in human cancers, and the quest for compounds that bind to mutant RAS remains a major goal, as it also does for inhibitors of protein-protein interactions. We have refined crystallization conditions for KRAS₁₆₉ ^Q61H-yielding crystals suitable for soaking with compounds and exploited this to assess new RAS-binding compounds selected by screening a protein-protein interaction-focused compound library using surface plasmon resonance. Two compounds, referred to as PPIN-1 and PPIN-2, with related structures from 30 initial RAS binders showed binding to a pocket where compounds had been previously developed, including RAS effector protein-protein interaction inhibitors selected using an intracellular antibody fragment (called Abd compounds). Unlike the Abd series of RAS binders, PPIN-1 and PPIN-2 compounds were not competed by the inhibitory anti-RAS intracellular antibody fragment and did not show any RAS-effector inhibition properties. By fusing the common, anchoring part from the two new compounds with the inhibitory substituents of the Abd series, we have created a set of compounds that inhibit RAS-effector interactions with increased potency. These fused compounds add to the growing catalog of RAS protein-protein inhibitors and show that building a chemical series by crossing over two chemical series is a strategy to create RAS-binding small molecules.