Differential Bioactivation Profiles of Different GS-441524 Prodrugs in Cell and Mouse Models: ProTide Prodrugs with High Cell Permeability and Susceptibility to Cathepsin A Are More Efficient in Delivering Antiviral Active Metabolites to the Lung.

We assessed factors that determine the tissue-specific bioactivation of ProTide prodrugs by comparing the disposition and activation of remdesivir (RDV), its methylpropyl and isopropyl ester analogues (MeRDV and IsoRDV, respectively), the oral prodrug GS-621763, and the parent nucleotide GS-441524 (Nuc). RDV and MeRDV yielded more active metabolite remdesivir-triphosphate (RDV-TP) than IsoRDV, GS-621763, and Nuc in human lung cell models due to superior cell permeability and higher susceptivity to cathepsin A. Intravenous administration to mice showed that RDV and MeRDV delivered significantly more RDV-TP to the lung than other compounds. Nevertheless, all four ester prodrugs exhibited very low oral bioavailability (<2%), with Nuc being the predominant metabolite in blood. In conclusion, ProTides prodrugs, such as RDV and MeRDV, are more efficient in delivering active metabolites to the lung than Nuc, driven by high cell permeability and susceptivity to cathepsin A. Optimizing ProTides' ester structures is an effective strategy for enhancing prodrug activation in the lung.

A nanomedicine composed of polymer-ss-DOX and polymer-Ce6 prodrugs with monoclonal antibody targeting effect for anti-tumor chemo-photodynamic synergetic therapy.

Anticancer drugs used for systemic chemotherapy often exhibit off-target toxicity and uncontrolled drug release due to their lack of targeting. To improve the bioavailability of drugs and reduce side effects, we have developed a mixed micelle of nanomedicine composed of two prodrugs with surface modified monoclonal antibody for cancer therapy. In this system, Nimotuzumab was used as targeting ligands of the mixed micelles (named as DCMMs) that is composed of polymer-doxorubicin prodrug (abbreviated as PEG-b-P(GMA-ss-DOX)) and maleimide polyethylene glycol-chlorin e6 (abbreviated as Mal-PEG-Ce6). The mixed micelles modified with Nimotuzumab (named as NTZ-DCMMs) bind to overexpressed EGFR receptors on Hepatoma-22 (H22) cells. Disulfide bonds in PEG-b-P(GMA-ss-DOX) are disrupted in tumor microenvironment, inducing the reduction-responsive release of DOX and leading to tumor cell apoptosis. Simultaneously, Chlorin e6 (Ce6) produced plenty of singlet oxygen (1O2) under laser irradiation to kill tumor cells. In vivo biological distribution and antineoplastic effect experiments demonstrate that NTZ-DCMMs enhanced drug enrichment at tumor sites through targeting function of antibody, dramatically suppressing tumor growth and mitigating cardiotoxicity of drugs. All results prove that NTZ-DCMMs have the ability to actively target H22 cells and quickly respond to tumor microenvironment, which is expected to become an intelligent and multifunctional drug delivery carrier for efficient chemotherapy and photodynamic therapy of hepatoma. STATEMENT OF SIGNIFICANCE: Anticancer drugs used for systemic chemotherapy often exhibit off-target toxicity due to their lack of targeting. Therefore, it's necessary to develop effective, targeted, and collaborative treatment strategies. We construct a mixed micelle of nanomedicine based on two polymer prodrugs and modified with monoclonal antibody on surface for cancer therapy. Under the tumor cell microenvironment, the disulfide bonds of polymer-ss-DOX were broken, effectively triggering DOX release. The photosensitizer Ce6 could generate a large amount of ROS under light, which synergistically promotes tumor cell apoptosis. By coupling antibodies to the hydrophilic segments of polymer micelles, drugs can be specifically delivered. Compared with monotherapy, the combination of chemotherapy and photodynamic therapy can significantly enhance the therapeutic effect of liver cancer.

First-in-human trial evaluating safety and pharmacokinetics of AT-752, a novel nucleotide prodrug with pan-serotype activity against dengue virus.

AT-752 is a novel guanosine nucleotide prodrug inhibitor of the dengue virus (DENV) polymerase with sub-micromolar, pan-serotype antiviral activity. This phase 1, double-blind, placebo-controlled, first-in-human study evaluated the safety, tolerability, and pharmacokinetics of ascending single and multiple oral doses of AT-752 in healthy subjects. AT-752 was well tolerated when administered as a single dose up to 1,500 mg or when administered as multiple doses up to 750 mg three times daily (TID). No serious adverse events occurred, and the majority of treatment-emergent adverse events were mild in severity and resolved by the end of the study. In those receiving single ascending doses of AT-752, no pharmacokinetic sensitivity was observed in Asian subjects, and no food effect was observed. Plasma exposure of the guanosine nucleoside metabolite AT-273, the surrogate of the active triphosphate metabolite of the drug, increased with increasing dose levels of AT-752 and exhibited a long half-life of approximately 15-25 h. Administration of AT-752 750 mg TID led to a rapid increase in plasma levels of AT-273 exceeding the target in vitro 90% effective concentration (EC90) of 0.64 µM in inhibiting DENV replication, and maintained this level over the treatment period. The favorable safety and pharmacokinetic results support the evaluation of AT-752 as an antiviral for the treatment of dengue in future clinical studies.Registered at ClinicalTrials.gov (NCT04722627).

Curcumin - Bioavailability Enhancement by Prodrug Approach and Novel Formulations.

Curcumin is a diverse natural pharmacological agent involved in various signal transduction mechanisms. Therapeutically, this potent molecule faces different challenges and issues related to low bioavailability due to its poor aqueous solubility, less permeability, faster elimination and clearance. Experts in synthetic chemistry and pharmaceuticals are continuously sparing their efforts to overcome these pharmacokinetic challenges by using different structural modification strategies and developing novel drug delivery systems. In this mini-review article, we are focusing on development of curcumin derivatives by different possible routes like conjugation with biomolecules, natural polymers, synthetic polymers, natural products, metal conjugates and co- administration with natural metabolic inhibitors. In addition to that, it was also focused on the preparation of modified formulations such as micelles, microemulsions, liposomes, complexes with phospholipids, micro and nanoemulsions, solid lipid nanoparticles, nano lipid carriers, biopolymer nanoparticles and microgels to improve the pharmacokinetic properties of the curcumin without altering its pharmacodynamics activity. This review helps to understand the problems associated with curcumin and different strategies to improve its pharmacokinetic profile.

Self-Reporting Molecular Prodrug for In Situ Quantitative Sensing of Drug Release by Ratiometric Photoacoustic Imaging.

Understanding the pharmacokinetics of prodrugs in vivo necessitates quantitative, noninvasive, and real-time monitoring of drug release, despite its difficulty. Ratiometric photoacoustic (PA) imaging, a promising deep tissue imaging technology with a unique capacity for self-calibration, can aid in solving this problem. Here, for the first time, a methylamino-substituted Aza-BODIPY (BDP-N) and the chemotherapeutic drug camptothecin (CPT) are joined via a disulfide chain to produce the molecular theranostic prodrug (BSC) for real-time tumor mapping and quantitative visualization of intratumoral drug release using ratiometric PA imaging. Intact BSC has an extremely low toxicity, with a maximum absorption at ∼720 nm; however, endogenous glutathione (GSH), which is overexpressed in tumors, will cleave the disulfide bond and liberate CPT (with full toxicity) and BDP-N. This is accompanied by a significant redshift in absorption at ∼800 nm, resulting in the PA800/PA720 ratio. In vitro, a linear relationship is successfully established between PA800/PA720 values and CPT release rates, and subsequent experiments demonstrate that this relationship can also be applied to the quantitative detection of intratumoral CPT release in vivo. Notably, the novel ratiometric strategy eliminates nonresponsive interference and amplifies the multiples of the signal response to significantly improve the imaging contrast and detection precision. Therefore, this research offers a viable alternative for the design of molecular theranostic agents for the clinical diagnosis and treatment of tumors.

Development of lipophilic ester prodrugs of dolutegravir for intestinal lymphatic transport.

The establishment of latent cellular and anatomical viral reservoirs is a major obstacle to achieving a cure for people infected by HIV. Mesenteric lymph nodes (MLNs) are one of the most important anatomical reservoirs of HIV. Suboptimal levels of antiretroviral (ARVs) drugs in these difficult-to-penetrate viral reservoirs is one of the limitations of current antiretroviral therapy (ART) regimens. This study aimed to design and assess highly lipophilic ester prodrugs of dolutegravir (DTG) formulated with long-chain triglyceride (LCT) for delivery of DTG to the viral reservoir in mesenteric lymph and MLNs. A number of alkyl ester prodrugs of DTG were designed based on the predicted affinity to chylomicrons (CM), and the six most promising prodrugs were selected and synthesised. The synthesised prodrugs were further assessed for their intestinal lymphatic transport potential and biotransformation in biorelevant media in vitro and ex vivo. DTG and the most promising prodrug (prodrug 5) were then assessed in pharmacokinetic and biodistribution studies in rats. Although oral administration of 5 mg/kg of unmodified DTG (an allometrically scaled dose from humans) with or without lipids achieved concentrations above protein binding-adjusted IC90 (PA-IC90) (64 ng/mL) in most tissues, the drug was not selectively targeted to MLNs. The combination of lipophilic ester prodrug and LCT-based formulation approach improved the targeting selectivity of DTG to MLNs 4.8-fold compared to unmodified DTG. However, systemic exposure to DTG was limited, most likely due to poor intestinal absorption of the prodrug following oral administration. In vitro lipolysis showed a good correlation between micellar solubilisation of the prodrug and systemic exposure to DTG in rats in vivo. Thus, it is prudent to include in vitro lipolysis in the early assessment of orally administered drugs and prodrugs in lipidic formulations, even when intestinal lymphatic transport is involved in the absorption pathway. Further studies are needed to clarify the underlying mechanisms of low systemic bioavailability of DTG following oral administration of the prodrug and potential ways to overcome this limitation.

Development and Pharmacokinetic Evaluation of Two Parenteral Formulations of Albendazole Using Prodrug and Cosolvent Approaches.

Albendazole is a broad-spectrum anthelmintic drug used for parasitic infections. In addition, due to its mechanism of action, it has been studied as an anticancer agent. However, poor and highly variable bioavailability are limiting factors for its use in systemic illnesses. The present study aimed to develop two parenteral formulations of albendazole and to compare its pharmacokinetic profile with the conventional oral administration. Parenteral formulations were developed using two different approaches: a phosphonooxymethylated prodrug and cosolvents. For the albendazole prodrug, once synthetized, its solubility and hydrolysis with alkaline phosphatase were evaluated. A factorial design of experiments was used for the cosolvent formulation. Stability and hemolytic activity were assessed. A pharmacokinetic study was performed on New Zealand rabbits. Both formulations were administered intravenously, and the prodrug was also administered intramuscularly. Results were compared with those obtained after the oral administration of albendazole. A 20,000-fold and 6000-fold increase in albendazole solubility was found with the prodrug and cosolvent formulations, respectively. Both parenteral formulations displayed higher albendazole plasma concentrations for the first 2 h compared with oral administration, even when the oral dose was doubled. The absolute bioavailability of oral albendazole was 15.5% while for the intramuscular administration of the prodrug was 102.6%. Both parenteral formulations showed a significant decrease in the formation of albendazole sulfoxide (ANOVA p<0.05) and allowed greater exposure to albendazole. Albendazole cosolvent parenteral formulation could be a promising option in systemic illnesses considering its ease of preparation and superb pharmacokinetic performance.

Preclinical Pharmacokinetic Profile of Topical Ophthalmic and Intravenous Delivery of QLS-101, a Novel ATP-Sensitive Potassium Channel Opening Ocular Hypotensive Agent.

Purpose: To evaluate the pharmacokinetic profiles of the ocular hypotensive agent QLS-101, a novel ATP-sensitive potassium channel opening prodrug, and its active moiety levcromakalim, following topical ophthalmic and intravenous dosing of normotensive rabbits and dogs. Methods: Dutch belted rabbits (n = 85) and beagle dogs (n = 32) were dosed with QLS-101 (0.16-3.2 mg/eye/dose) or formulation buffer for 28 days. Pharmacokinetic profiles of QLS-101 and levcromakalim were evaluated in ocular tissues and blood by LC-MS/MS. Tolerability was assessed by clinical and ophthalmic examinations. Maximum systemic tolerated dose was evaluated in beagle dogs (n = 2) following intravenous bolus administrations of QLS-101 (0.05 to 5 mg/kg). Results: Plasma analysis following topical dosing of QLS-101 (0.8-3.2 mg/eye/dose) for 28 days indicated an elimination half-life (T1/2) of 5.50-8.82 h and a corresponding time (Tmax) range of 2-12 h in rabbits, and a T1/2 of 3.32-6.18 h with a Tmax range of 1-2 h in dogs. Maximum tissue concentration (Cmax) values ranged from 54.8-540 (day 1) to 50.5-777 ng/mL (day 28) in rabbits, and 36.5-166 (day 1) to 47.0-147 ng/mL (day 28) in dogs. Levcromakalim plasma T1/2 and Tmax were similar to QLS-101, while Cmax was consistently lower. Topical ophthalmic delivery of QLS-101 was well tolerated in both species, with sporadic mild ocular hyperemia noted in the group treated with the highest concentration (3.2 mg/eye/dose). Following topical ophthalmic dosing, QLS-101 and levcromakalim were found primarily in the cornea, sclera, and conjunctiva. Maximum tolerated dose was determined to be 3 mg/kg. Conclusions: QLS-101 was converted to its active moiety levcromakalim and showed characteristic absorption, distribution, and safety profiles of a well-tolerated prodrug.

Emerging nanoparticle platforms to improve the administration of glucocorticoids.

Glucocorticoids (GC) are common drugs used to treat acute and chronic inflammatory diseases, whose prolonged use can result in severe side effects hampering their efficacy. In addition, the pharmacokinetics, and biodistribution of GC are inadequate to support high efficacy with reduced toxicity. Following the marketing of GC prodrugs, new GC prodrug entities, and conjugates, have been developed. These new prodrugs and conjugates have been administered in free form or under a nanoparticulate form for local or systemic administration. These nanoparticles from lipid prodrugs and nanoconjugates change the paradigm of GC delivery, solving the issue of low drug loading into nanoparticles and circumventing the potential burst release effect by allowing a more controlled delivery of the GC and better targeting in inflammatory sites. This review highlights the design strategies, recent advances in GC prodrugs and conjugates, and their delivery in nanoparticulate form, demonstrating the strong potentialities of these novel strategies.

Population pharmacokinetics and exposure-safety of lipophilic conjugates prodrug DP-VPA in healthy Chinese subjects for dose regime exploring.

Phospholipid-valproic acid (DP-VPA)is a prodrug for treating epilepsy. The present study explored the pharmacokinetics (PK) and exposure safety of DP-VPA to provide a basis for future studies exploring the safe dosage and therapeutic strategies for epilepsy. The study included a randomized placebo-controlled dose-escalation tolerance evaluation trial and a randomized triple crossover food-effect trial in healthy Chinese volunteers. A population pharmacokinetic (PopPK) model was established to analyze the PK of DP-VPA and active metabolite VPA. The exposure safety was assessed with the adverse drug reaction (ADR) in CNS. The PopPK of DP-VPA and metabolite VPA fitted a two-compartment model coupling one-compartment with Michaelis-Menten metabolite kinetics and first-order elimination. The absorption processes after single oral administration of DP-VPA tablet demonstrated nonlinear characteristics, including 0-order kinetic phase and time-dependent phase fitting Weibull distribution. The final model indicated that the DP-VPA PK was significantly affected by dosage and food. The exposure-safety relationship demonstrated a generalized linear regression; mild/moderate ADRs occurred in some subjects with 600 mg and all subjects with 1500 mg of DP-VPA, and no severe ADRs were reported up to 2400 mg. In conclusion, the study established a PopPK model describing the processing of DP-VPA and VPA in healthy Chinese subjects. DP-VPA showed good tolerance after a single dose of 600-2400 mg with nonlinear PK and was affected by dosage and food. Based on the association between neurological ADRs and higher exposure to DP-VPA by exposure-safety analysis, 900-1200 mg was recommended for subsequent study of safety and clinical effectiveness.

Novel Pt(IV) prodrug self-assembled nanoparticles with enhanced blood circulation stability and improved antitumor capacity of oxaliplatin for cancer therapy.

Pt(IV) compounds are regarded as prodrugs of active Pt(II) drugs (i.e. cisplatin, carboplatin, and oxaliplatin) and burgeoned as the most ideal candidates to substitute Pt(II) anticancer drugs with severe side effects. Nanoparticle drug delivery systems have been widely introduced to deliver Pt(IV) prodrugs more effectively and safely to tumors, but clinical outcomes were unpredictable owing to limited in vivo pharmacokinetics understanding. Herein, a novel Pt(IV) prodrug of oxaliplatin(OXA) was synthesized and prepared as self-assembled micellar nanoparticles(PEG-OXA NPs). In vitro, PEG-OXA NPs rapidly released biologically active OXA within 5 min in tumor cells while remaining extremely stable in whole blood or plasma. Importantly, the pharmacokinetic results showed that the AUC0-∞, and t1/2 values of PEG-OXA NPs were 1994 ± 117 h·µg/mL and 3.28 ± 0.28 h, respectively, which were much higher than that of free OXA solution (2.03 ± 0.55 h·µg/mL and 0.16 ± 0.07 h), indicating the longer drug circulation of PEG-OXA NPs in vivo. The altered pharmacokinetic behavior of PEG-OXA NPs remarkably contributed to improve antitumor efficacy, decrease systemic toxicity and increase tumor growth inhibition compared to free OXA. These findings establish that PEG-OXA NPs have the potential to offer a desirable self-delivery platform of platinum drugs for anticancer therapeutics.

Utility of a Systematic Approach to Selecting Candidate Prodrugs: A Case Study Using Candesartan Ester Analogues.

Development of prodrugs is a useful strategy to overcome some disadvantages of candidate drugs. Recently, we established a systematic approach to selecting appropriate prodrugs, and validated the utility of this approach using oseltamivir analogues. In this study, the utility of the approach was further examined using candesartan cilexetil and 20 kinds of its analogues having various types of side chain as model compounds. Log D values of analogues (2.5 to 4.7) were higher than that of candesartan (1.0), their active metabolite, and the results were reasonable for the purpose of improving permeability of candesartan. The analogues tended to be more soluble in artificial intestinal fluids than in artificial gastric fluid, owing to their acidic physicochemical characteristics. Their membrane permeabilities were not correlated with log D values, which can be attributed to the metabolism in Caco-2 cells used in this system. In human hepatocytes and enterocytes, 11 out of the 20 analogues were immediately hydrolyzed to candesartan, and species differences were observed in the hydrolysis efficiency. This study confirmed the utility of the systematic approach for selection of appropriate prodrugs that could be proceeded to in vivo pharmacokinetics study, with selection of suitable experimental animals.

Single-Ascending-Dose, Food-Effect, and Multiple-Dose Study of the Safety, Tolerability, and Pharmacokinetics of the Pangenotypic Anti-Hepatitis C Virus Drug Holybuvir in Healthy Chinese Subjects.

Holybuvir is a novel pangenotypic hepatitis C virus NS5B inhibitor. This first in-human study aimed to evaluate the pharmacokinetics (PK), safety, and tolerability of holybuvir and its metabolites and the effect of food on the PK of holybuvir and its metabolites in healthy Chinese subjects. A total of 96 subjects were enrolled in this study which included (i) a single-ascending-dose (SAD) study (100 to 1,200 mg), (ii) a food-effect (FE) study (600 mg), and (iii) a multiple-dose (MD) study (400 and 600 mg once daily for 14 days). The results showed that single oral administration of holybuvir at doses up to 1,200 mg was well tolerated. Holybuvir was rapidly absorbed and metabolized in the human body, which was consistent with the characteristics of holybuvir as a prodrug. PK analysis showed that Cmax and area under the curve (AUC) increased with dose in no dose-proportional manner after a single-dose administration (100 to 1,200 mg). Although high-fat meals did change the PK of holybuvir and its metabolites, clinical significance of changes in PK parameters induced by eating a high-fat diet would be further confirmed. Following multiple-dose administration, accumulation of metabolites SH229M4 and SH229M5-sul was observed. The favorable PK and safety results support the further development of holybuvir for patients with HCV. (This study was registered at Chinadrugtrials.org under identifier CTR20170859.).

Prediction of the Renal Organic Anion Transporter 1 (OAT1)- Mediated Drug Interactions for LY404039, the Active Metabolite of Pomaglumetad Methionil.

PURPOSE: The objective of this work was to demonstrate that clinical OAT1-mediated DDIs can be predicted using physiologically based pharmacokinetic (PBPK) modeling. METHODS: LY404039 is a metabotropic glutamate receptor 2/3 agonist and the active moiety of the prodrug pomaglumetad methionil (LY2140023). After oral administration, pomaglumetad methionil is rapidly taken up by enterocytes via PEPT1 and once absorbed, converted to LY404039 via membrane dehydropeptidase 1 (DPEP1). LY404039 is renally excreted by both glomerular filtration and active secretion and in vitro studies showed that the active secretion of LY404039 was mediated by the organic anion transporter 1 (OAT1). Both clinical and in vitro data were used to build a PBPK model to predict OAT1-mediated DDIs. RESULTS: In vitro inhibitory potencies (IC50) of the known OAT inhibitors, probenecid and ibuprofen, were determined to be 4.00 and 2.63 µM, respectively. Subsequently, clinical drug-drug interaction (DDI) study showed probenecid reduced the renal clearance of LY404039 by 30 to 40%. The PBPK bottom-up model, predicted a renal clearance that was approximately 20% lower than the observed one. The middle-out model, using an OAT1 relative activity factor (RAF) of 3, accurately reproduced the renal clearance of LY404039 and pharmacokinetic (PK) changes of LY404039 in the presence of probenecid. CONCLUSIONS: OAT1- mediated DDIs can be predicted using in vitro measured IC50 and PBPK modeling. The effect of ibuprofen was predicted to be minimal (AUC ratio of 1.15) and not clinically relevant.

Prodrugs of a 1-Hydroxy-2-oxopiperidin-3-yl Phosphonate Enolase Inhibitor for the Treatment of ENO1-Deleted Cancers.

Cancers harboring homozygous deletion of the glycolytic enzyme enolase 1 (ENO1) are selectively vulnerable to inhibition of the paralogous isoform, enolase 2 (ENO2). A previous work described the sustained tumor regression activities of a substrate-competitive phosphonate inhibitor of ENO2, 1-hydroxy-2-oxopiperidin-3-yl phosphonate (HEX) (5), and its bis-pivaloyoxymethyl prodrug, POMHEX (6), in an ENO1-deleted intracranial orthotopic xenograft model of glioblastoma [Nature Metabolism 2020, 2, 1423-1426]. Due to poor pharmacokinetics of bis-ester prodrugs, this study was undertaken to identify potential non-esterase prodrugs for further development. Whereas phosphonoamidate esters were efficiently bioactivated in ENO1-deleted glioma cells, McGuigan prodrugs were not. Other strategies, including cycloSal and lipid prodrugs of 5, exhibited low micromolar IC50 values in ENO1-deleted glioma cells and improved stability in human serum over 6. The activity of select prodrugs was also probed using the NCI-60 cell line screen, supporting its use to examine the relationship between prodrugs and cell line-dependent bioactivation.

Design and Characterization of a Natural Arf-GEFs Inhibitor Prodrug CHNQD-01255 with Potent Anti-Hepatocellular Carcinoma Efficacy In Vivo.

Brefeldin A (BFA), a well-known natural Arf-GEFs inhibitor, is effective against hepatocellular carcinoma (HCC), while the poor solubility, serious toxicity, and short half-life limit its potential. Herein, distinct corresponding prodrugs of BFA, including esters 1-15, carbonates 16-24 and 30-32, and carbamates 25-29, were synthesized and evaluated. CHNQD-01255 (16) with improved aqueous solubility (15-20 mg/mL) demonstrated favorable pharmacokinetic profiles. It behaved as expected by undergoing rapid conversion to BFA in vivo, and achieved sufficient high plasma exposure, prolonged half-life, as well as the improved bioavailability of BFA (F = 18.96%). Meanwhile, CHNQD-01255 significantly suppressed tumor growth (TGI = 61.0%) at a dose of 45 mg/kg (p.o.) in the xenograft model. Notably, the improved safety profile of CHNQD-01255 (MTD > 750 mg/kg, p.o.) was confirmed to be superior to that of BFA (MTD < 506 mg/kg). Overall, CHNQD-01255 may serve as a safe and effective new anti-HCC prodrug.

A translational strategy employing physiologically based modelling to predict the pharmacological active dose of RO7119929, an oral prodrug of a targeted cancer immunotherapy TLR7 agonist.

RO7119929 is being developed as an orally administered prodrug of the TLR7-specific agonist and active drug, RO7117418, for the treatment of patients with solid tumours.In this publication, we present a case study wherein the human pharmacokinetics and pharmacological active dose were prospectively predicted following oral administration of the prodrug.A simple translational pharmacokinetic-pharmacodynamic strategy was applied to predict the pharmacological active dose of the prodrug in human. In vivo studies in monkey showed that an unbound plasma exposure of active drug of 1.5 ng/mL elicited secretion of key serum pharmacodynamic cytokine and chemokine biomarkers in monkey. This threshold of 1.5 ng/mL was close to the minimum effective concentration of active drug required to induce cytokine secretion in human peripheral blood mononuclear cells (3 ng/mL).Measured in vitro physicochemical and biochemical properties of the prodrug and active drug were applied as input parameters in physiologically based pharmacokinetic models to predict the pharmacokinetics of active drug after oral dosing of the prodrug in humans. Then, using the PBPK model, a dose which delivered an unbound plasma Cmax in line with the target pharmacodynamic threshold of 1.5 ng/mL was found. This defined the lowest pharmacologically active dose as 3 mg.The prodrug entered the clinic in 2020 in patients with primary or secondary liver cancers. Clear pharmacodynamic, transient, and dose-dependent cytokine induction was observed at prodrug doses > 1 mg.

Discovery of Orally Bioavailable and Brain-Penetrable Prodrugs of the Potent nSMase2 Inhibitor DPTIP.

Extracellular vesicles (EVs) can carry pathological cargo and play an active role in disease progression. Neutral sphingomyelinase-2 (nSMase2) is a critical regulator of EV biogenesis, and its inhibition has shown protective effects in multiple disease states. 2,6-Dimethoxy-4-(5-phenyl-4-thiophen-2-yl-1H-imidazol-2-yl)phenol (DPTIP) is one of the most potent (IC50 = 30 nM) inhibitors of nSMase2 discovered to date. However, DPTIP exhibits poor oral pharmacokinetics (PK), limiting its clinical development. To overcome DPTIP's PK limitations, we synthesized a series of prodrugs by masking its phenolic hydroxyl group. When administered orally, the best prodrug (P18) with a 2',6'-diethyl-1,4'-bipiperidinyl promoiety exhibited >fourfold higher plasma (AUC0-t = 1047 pmol·h/mL) and brain exposures (AUC0-t = 247 pmol·h/g) versus DPTIP and a significant enhancement of DPTIP half-life (2 h vs ∼0.5 h). In a mouse model of acute brain injury, DPTIP released from P18 significantly inhibited IL-1ß-induced EV release into plasma and attenuated nSMase2 activity. These studies report the discovery of a DPTIP prodrug with potential for clinical translation.

Intelligent triggering of nanomicelles based on a ROS-activated anticancer prodrug and photodynamic therapy (PDT)-synergistic therapy for lung cancers.

The intelligent triggering of drug release at targeted sites is essential for the safety and efficacy of cancer therapies. This study aimed to design and synthesize a novel prodrug (DHA-S-CA) using a reactive oxygen species (ROS)-responsive moiety, thioacetal, to bridge cinnamaldehyde (CA) and dihydroartemisinin (DHA). As ROS are highly expressed in tumor tissues, the design uses the ROS-responsive moiety as an effective target for the nanodrug delivery system. Furthermore, the near-infrared dye IR808 and the prodrug were adopted to prepare co-loaded Soluplus®/TPGS nanomicelles (IR808/DHA-S-CA NMs). The photosensitized agent IR808 exhibited both tumor accumulation and cancer imaging properties while generating ROS during laser irradiation. Intracellular ROS detection indicated that the prodrug DHA-S-CA could degrade via the high concentration of ROS in cancer cells induced by laser irradiation, and the released CA stimulated mitochondria to regenerate additional ROS to further improve the antitumor effect of DHA. Combined with photodynamic therapy (PDT), IR808/DHA-S-CA (+) NMs outperformed free DHA, DHA NMs, and IR808/DHA-S-CA (-) in a comparison of their pharmacokinetic profiles because it had a longer circulation time and a greater area under the curve (AUC). Compared with other DHA groups, the ROS-responsive IR808/DHA-S-CA (+) micelles had comparable cytotoxic activity. Furthermore, the ROS-responsive IR808/DHA-S-CA (+) micelles exhibited markedly higher anticancer efficiency on lung cancer cells than the other DHA groups. Overall, these results indicated that the therapeutic strategy of our novel small-molecule prodrug combined with PDT has great potential for the treatment of tumors.

Glucuronides: From biological waste to bio-nanomedical applications.

Long considered as no more than biological waste meant to be eliminated in urine, glucuronides have recently contributed to tremendous developments in the biomedical field, particularly against cancer. While glucuronide prodrugs monotherapy and antibody-directed enzyme prodrug therapy have been around for some time, new facets have emerged that combine the unique properties of glucuronides notably in the fields of antibody-drug conjugates and nanomedicine. In both cases, glucuronides are utilized as a vector to improve pharmacokinetics and confer localized activation of potent drugs at tumor sites while also decreasing systemic toxicity. Here we will discuss some of the most promising strategies using glucuronides to promote successful anti-tumor therapeutic treatments.