Seeking an optimal dosing regimen for OZ439/DSM265 combination therapy for treating uncomplicated falciparum malaria.

BACKGROUND: The efficacy of artemisinin-based combination therapies (ACTs), the first-line treatments for uncomplicated falciparum malaria, has been declining in malaria-endemic countries due to the emergence of malaria parasites resistant to these compounds. Novel alternative therapies are needed urgently to prevent the likely surge in morbidity and mortality due to failing ACTs. OBJECTIVES: This study investigates the efficacy of the combination of two novel drugs, OZ439 and DSM265, using a biologically informed within-host mathematical model. METHODS: A within-host model was developed, which accounts for the differential killing of these compounds against different stages of the parasite's life cycle and accommodates the pharmacodynamic interaction between the drugs. Data of healthy volunteers infected with falciparum malaria collected from four trials (three that administered OZ439 and DSM265 alone, and the fourth a combination of OZ439 and DSM265) were analysed. Model parameters were estimated in a hierarchical Bayesian framework. RESULTS: The posterior predictive simulations of our model predicted that 800 mg of OZ439 combined with 450 mg of DSM265, which are within the safe and tolerable dose range, can provide above 90% cure rates 42 days after drug administration. CONCLUSIONS: Our results show that the combination of OZ439 and DSM265 can be a promising alternative to replace ACTs. Our model can be used to inform future Phase 2 and 3 clinical trials of OZ439/DSM265, fast-tracking the deployment of this combination therapy in the regions where ACTs are failing. The dosing regimens that are shown to be efficacious and within safe and tolerable limits are suggested for future investigations.

Design, Synthesis, and Biological Evaluation of Novel Pyrimido[4,5-b]indole Derivatives Against Gram-Negative Multidrug-Resistant Pathogens.

Due to the poor permeability across Gram-negative bacterial membranes and the troublesome bacterial efflux mechanism, only a few GyrB/ParE inhibitors with potent activity against Gram-negative pathogens have been reported. Among them, pyrimido[4,5-b]indole derivatives represented by GP-1 demonstrated excellent broad-spectrum antibacterial activity against both Gram-positive and Gram-negative bacteria but were limited by hERG inhibition and poor pharmacokinetics profile. To improve their drug-like properties, we designed a series of novel pyrimido[4,5-b]indole derivatives based on the tricyclic scaffold of GP-1 and the C-7 moiety of acorafloxacin. These efforts have culminated in the discovery of a promising compound 18r with reduced hERG liability and an improved PK profile. Compound 18r exhibited superior broad-spectrum in vitro antibacterial activity compared to GP-1, including a variety of clinical multidrug G- pathogens, especially Acinetobacter baumannii, and the in vivo efficacy was also demonstrated in a neutropenic mouse thigh model of infection with multidrug-resistant A. baumannii.

Translational and pharmacokinetic-pharmacodynamic application for the clinical development of GDC-0334, a novel TRPA1 inhibitor.

GDC-0334 is a novel small molecule inhibitor of transient receptor potential cation channel member A1 (TRPA1), a promising therapeutic target for many nervous system and respiratory diseases. The pharmacokinetic (PK) profile and pharmacodynamic (PD) effects of GDC-0334 were evaluated in this first-in-human (FIH) study. A starting single dose of 25 mg was selected based on integrated preclinical PK, PD, and toxicology data following oral administration of GDC-0334 in guinea pigs, rats, dogs, and monkeys. Human PK and PK-PD of GDC-0334 were characterized after single and multiple oral dosing using a population modeling approach. The ability of GDC-0334 to inhibit dermal blood flow (DBF) induced by topical administration of allyl isothiocyanate (AITC) was evaluated as a target-engagement biomarker. Quantitative models were developed iteratively to refine the parameter estimates of the dose-concentration-effect relationships through stepwise estimation and extrapolation. Human PK analyses revealed that bioavailability, absorption rate constant, and lag time increase when GDC-0334 was administered with food. The inhibitory effect of GDC-0334 on the AITC-induced DBF biomarker exhibited a clear sigmoid-Emax relationship with GDC-0334 plasma concentrations in humans. This study leveraged emerging preclinical and clinical data to enable iterative refinement of GDC-0334 mathematical models throughout the FIH study for dose selection in subsequent cohorts throughout the study. Study Highlights WHAT IS THE CURRENT KNOWLEDGE ON THE TOPIC? GDC-0334 is a novel, small molecule TRPA1 inhibitor and a pharmacokinetic-pharmacodynamic (PK-PD) modeling strategy could be implemented in a systematic and step-wise manner to build and learn from emerging data for early clinical development. WHAT QUESTION DID THIS STUDY ADDRESS? Can noncompartmental and population-based analyses be used to describe the PK and PD characteristics of GDC-0334 in preclinical and clinical studies? WHAT DOES THIS STUDY ADD TO OUR KNOWLEDGE? GDC-0334 exposure generally increased with dose in rats, dogs, and monkeys. The starting dose (25 mg) in the clinical study was determined based on the preclinical data. GDC-0334 exhibited linear PK in humans and the bioavailability was increased with food. The inhibitory effect of GDC-0334 on dermal blood flow induced by the TRPA1 agonist allyl isothiocyanate in humans indicates a clear PK-PD relationship. HOW MIGHT THIS CHANGE CLINICAL PHARMACOLOGY OR TRANSLATIONAL SCIENCE? The models developed based on TRPA1 agonist-induced dermal blood flow inhibition data can be used to predict PK-PD relationships in future preclinical and clinical studies evaluating new drug entities that target TRPA1.

Etravirine-loaded dissolving microneedle arrays for long-acting delivery.

A key challenge of HIV treatment with multiple antiretroviral drugs is patient adherence. Thus, there is an urgent need for long-acting depot systems for delivering drugs over an extended duration. Although the parenteral route is preferred for depot systems, it is associated with obvious drawbacks, such as painful injections, potentially-contaminated sharps waste, and the necessity of trained healthcare personnel for administration. Amongst a small number of alternatives in development microneedles are versatile delivery systems enabling systemic drug delivery and potentially improving patient adherence due to their capacity for self-administration. We have developed dissolving microneedle (DMNs) embedded with etravirine nanosuspension (ETR NS) as a long-acting HIV therapy to improve patient adherence. The ETR NS prepared by sonoprecipitation yielded particle sizes of 764 ± 96.2 nm, polydispersity indices of of 0.23 ± 0.02, and zeta potentials of -19.75 ± 0.55 mV. The DMNs loaded with ETR NS demonstrated 12.84 ± 1.33% ETR deposition in ex-vivo neonatal porcine skin after 6 h application. In in vivo rat pharmacokinetic studies, the Cmax exhibited by DMNs loaded with ETR powder and ETR NS were 158 ± 10 ng/mL and 177 ± 30 ng/mL, respectively. DMN groups revealed a higher t1/2, Tmax, and mean residence time compared to intravenous ETR solutions, suggesting the long-acting potential of etravirine delivered intradermally using DMNs.

Structure-Based Virtual Screening Identifies Multiple Stable Binding Sites at the RecA Domains of SARS-CoV-2 Helicase Enzyme.

With the emergence and global spread of the COVID-19 pandemic, the scientific community worldwide has focused on search for new therapeutic strategies against this disease. One such critical approach is targeting proteins such as helicases that regulate most of the SARS-CoV-2 RNA metabolism. The purpose of the current study was to predict a library of phytochemicals derived from diverse plant families with high binding affinity to SARS-CoV-2 helicase (Nsp13) enzyme. High throughput virtual screening of the Medicinal Plant Database for Drug Design (MPD3) database was performed on SARS-CoV-2 helicase using AutoDock Vina. Nilotinib, with a docking value of -9.6 kcal/mol, was chosen as a reference molecule. A compound (PubChem CID: 110143421, ZINC database ID: ZINC257223845, eMolecules: 43290531) was screened as the best binder (binding energy of -10.2 kcal/mol on average) to the enzyme by using repeated docking runs in the screening process. On inspection, the compound was disclosed to show different binding sites of the triangular pockets collectively formed by Rec1A, Rec2A, and 1B domains and a stalk domain at the base. The molecule is often bound to the ATP binding site (referred to as binding site 2) of the helicase enzyme. The compound was further discovered to fulfill drug-likeness and lead-likeness criteria, have good physicochemical and pharmacokinetics properties, and to be non-toxic. Molecular dynamic simulation analysis of the control/lead compound complexes demonstrated the formation of stable complexes with good intermolecular binding affinity. Lastly, affirmation of the docking simulation studies was accomplished by estimating the binding free energy by MMPB/GBSA technique. Taken together, these findings present further in silco investigation of plant-derived lead compounds to effectively address COVID-19.

Translational pharmacokinetic-pharmacodynamic modeling of preclinical and clinical data of the oral MET inhibitor tepotinib to determine the recommended phase II dose.

Tepotinib is a highly selective and potent MET inhibitor in development for the treatment of patients with solid tumors. Given the favorable tolerability and safety profiles up to the maximum tested dose in the first-in-human (FIH) trial, an efficacy-driven translational modeling approach was proposed to establish the recommended phase II dose (RP2D). To study the in vivo pharmacokinetics (PKs)/target inhibition/tumor growth inhibition relationship, a subcutaneous KP-4 pancreatic cell-line xenograft model in mice with sensitivity to MET pathway inhibition was selected as a surrogate tumor model. Further clinical PK and target inhibition data (derived from predose and postdose paired tumor biopsies) from a FIH study were integrated with the longitudinal PKs and target inhibition profiles from the mouse xenograft study to establish a translational PK/pharmacodynamic (PD) model. Preclinical data showed that tumor regression with tepotinib treatment in KP-4 xenograft tumors corresponded to 95% target inhibition. We therefore concluded that a PD criterion of sustained, near-to-complete (>95%) phospho-MET inhibition in tumors should be targeted for tepotinib to be effective. Simulations of dose-dependent target inhibition profiles in human tumors that exceeded the PD threshold in more than 90% of patients established an RP2D of tepotinib 500 mg once daily. This translational mathematical modeling approach supports an efficacy-driven rationale for tepotinib phase II dose selection of 500 mg once daily. Tepotinib at this dose has obtained regulatory approval for the treatment of patients with non-small cell lung cancer harboring MET exon 14 skipping.

Tofacitinib and Baricitinib Are Taken up by Different Uptake Mechanisms Determining the Efficacy of Both Drugs in RA.

BACKGROUND: Rheumatoid arthritis (RA) is a systemic autoimmune disease in which synovial fibroblasts (SF) play a key role. Baricitinib and Tofacitinib both act intracellularly, blocking the ATP-binding side of JAK proteins and thereby the downstream signalling pathway via STAT-3. Therefore, we investigated the role of organic cation transporters (OCTs) in Baricitinib and Tofacitinib cellular transport. METHODS: OCT expression was analysed in SF isolated from RA and osteoarthritis (OA) patients, as well as peripheral blood mononuclear cells. The interaction of Baricitinib and Tofacitinib with OCTs was investigated using quenching experiments. The intracellular accumulation of both drugs was quantified using LC/MS. Target inhibition for both drugs was tested using Western blot for phosphorylated JAK1 and STAT3 upon stimulation with IL-6. RESULTS: MATE-1 expression increased in OASF compared to RASF. The other OCTs were not differentially expressed. The transport of Baricitinib was not OCT dependent. Tofacitinib; however, was exported from RASF in a MATE-1 dependent way. Tofacitinib and Baricitinib showed comparable inhibition of downstream signalling pathways. CONCLUSION: We observed different cellular uptake strategies for Baricitinib and Tofacitinib. Tofacitinib was exported out of healthy cells due to the increased expression of MATE1. This might make Tofacitinib the favourable drug.

Safety assessment of metarrestin in dogs: A clinical candidate targeting a subnuclear structure unique to metastatic cancer cells.

Pancreatic cancer is a leading cause of cancer-related deaths in the U.S. Ninety percent of patients with stage IV pancreatic cancer die within one year of diagnosis due to complications of metastasis. A metastatic potential of cancer cells has been shown to be closely associated with formation of perinucleolar compartment (PNC). Metarrestin, a first-in-class PNC inhibitor, was evaluated for its toxicity, toxicokinetics, and safety pharmacology in beagle dogs following every other day oral (capsule) administration for 28 days to support its introduction into clinical trials. The study consisted of four dose groups: vehicle; 0.25, 0.75 and 1.50 mg/kg/dose. Metarrestin reached its maximum concentration in blood at 3 h (overall median Tmax) across all doses with a mean t1/2 over 168 h of 55.5 h. Dose dependent increase in systemic exposure (Cmax and AUClast) with no sex difference was observed on days 1 and 27. Metarrestin accumulated from Day 1 to Day 27 at all dose levels and in both sexes by an overall factor of about 2.34. No mortality occurred during the dosing period; however, treatment-related clinical signs of toxicity consisting of hypoactivity, shaking/shivering, thinness, irritability, salivation, abnormal gait, tremors, ataxia and intermittent seizure-like activity were seen in both sexes at mid and high dose groups. Treatment-related effects on body weight and food consumption were seen at the mid and high dose levels. Safety pharmacology study showed no treatment-related effects on blood pressure, heart rate, corrected QT, PR, RR, or QRS intervals, or respiratory function parameters (respiratory rate, tidal volume, minute volume). There were no histopathological changes observed, with the exception of transient thymic atrophy which was considered to be non-adverse. Based primarily on clinical signs of toxicity, the No Observed Adverse Effect Level (NOAEL) in dogs was considered to be 0.25 mg/kg metarrestin after every other day dosing for 28 days with a mean of male and female Cmax = 82.5 ng/mL and AUClast = 2521 h*ng/mL, on Day 27.

Metabolism and Pharmacokinetic Drug-Drug Interaction Profile of Vericiguat, A Soluble Guanylate Cyclase Stimulator: Results From Preclinical and Phase I Healthy Volunteer Studies.

BACKGROUND: Vericiguat is a stimulator of soluble guanylate cyclase currently under investigation as a first-in-class therapy for worsening chronic heart failure (NCT02861534). Patients with heart failure often require polypharmacy because of comorbidities. Hence, understanding the clearance mechanisms, elimination, and potential for pharmacokinetic drug-drug interactions of vericiguat is important for dose recommendations in this patient population. METHODS: Biotransformation and perpetrator properties of vericiguat were characterized in vitro using human hepatocytes, liver microsomes, and recombinant enzymes. This was complemented by a human mass balance study and ten drug-drug interaction studies in healthy volunteers wherein vericiguat was co-administered orally with omeprazole, magnesium/aluminum hydroxide, ketoconazole, rifampicin, mefenamic acid, midazolam, warfarin, digoxin, sacubitril/valsartan, aspirin, or sildenafil. RESULTS: In the human mass balance study, mean total radioactivity recovered was 98.3% of the dose administered (53.1% and 45.2% excreted via urine and feces, respectively). The main metabolic pathway of vericiguat is glucuronidation via uridine diphosphate-glucuronosyltransferase 1A9 and 1A1. In vitro studies revealed a low risk of vericiguat acting as a perpetrator by inhibiting cytochrome P450s, uridine diphosphate-glucuronosyltransferase isoforms, or major transport proteins, or by inducing cytochrome P450s. These observations were supported by phase I drug-drug interaction studies. Phase I studies that assessed the propensity of vericiguat as a victim drug showed changes in the range that did not warrant recommendations for dose adjustment in phase III. CONCLUSIONS: A low pharmacokinetic interaction potential of vericiguat was estimated from in vitro data and confirmed in vivo. Thus, vericiguat is suitable for a patient population with multiple comorbidities requiring polypharmacy.

Metabolism and pharmacokinetics characterization of metarrestin in multiple species.

PURPOSE: Metarrestin is a first-in-class pyrrolo-pyrimidine-derived small molecule targeting a marker of genome organization associated with metastasis and is currently in preclinical development as an anti-cancer agent. Here, we report the in vitro ADME characteristics and in vivo pharmacokinetic behavior of metarrestin. METHODS: Solubility, permeability, and efflux ratio as well as in vitro metabolism of metarrestin in hepatocytes, liver microsomes and S9 fractions, recombinant cytochrome P450 (CYP) enzymes, and potential for CYP inhibition were evaluated. Single dose pharmacokinetic profiles after intravenous and oral administration in mice, rat, dog, monkey, and mini-pig were obtained. Simple allometric scaling was applied to predict human pharmacokinetics. RESULTS: Metarrestin had an aqueous solubility of 150 µM at pH 7.4, high permeability in PAMPA and moderate efflux ratio in Caco-2 assays. The compound was metabolically stable in liver microsomes, S9 fractions, and hepatocytes from six species, including human. Metarrestin is a CYP3A4 substrate and, in mini-pigs, is also directly glucuronidated. Metarrestin did not show cytochrome P450 inhibitory activity. Plasma concentration-time profiles showed low to moderate clearance, ranging from 0.6 mL/min/kg in monkeys to 48 mL/min/kg in mice and moderate to high volume of distribution, ranging from 1.5 L/kg in monkeys to 17 L/kg in mice. Metarrestin has greater than 80% oral bioavailability in all species tested. The excretion of unchanged parent drug in urine was < 5% in dogs and < 1% in monkeys over collection periods of ≥ 144 h; in bile-duct cannulated rats, the excretion of unchanged drug was < 1% in urine and < 2% in bile over a collection period of 48 h. CONCLUSIONS: Metarrestin is a low clearance compound which has good bioavailability and large biodistribution after oral administration. Biotransformation appears to be the major elimination process for the parent drug. In vitro data suggest a low drug-drug interaction potential on CYP-mediated metabolism. Overall favorable ADME and PK properties support metarrestin's progression to clinical investigation.

Tumor-targeted delivery of silibinin and IPI-549 synergistically inhibit breast cancer by remodeling the microenvironment.

We induced changes in the tumor microenvironment (TME) through the synergistic actions of two drugs used in breast cancer therapy. The anti-fibrotic drug silibinin (SLB) targets tumor-associated fibroblasts and exerts immune-mediated anti-cancer effects. IPI-549, an efficient and highly selective phosphoinositide-3-kinase-gamma (PI3Kγ) inhibitor, was applied to alter the balance of immunosuppressive cells by inhibiting PI3Kγ molecules; it also promotes anti-tumor immunity. We developed nanoparticle formulations to encapsulate both drugs into the targeting carrier aminoethyl anisamide-polyethylene glycol-polycaprolactone (AEAA-PEG-PCL) respectively. The drugs were intravenously delivered in mice and resulted in an increase in anti-tumor efficacy and apoptotic tumor tissue compared with either IPI-549 or SLB alone in 4T1 breast cancer cell-derived tumors. Furthermore, a significant reduction in regulatory T (Treg) cells and myeloid suppressor cells (MDSCs) was observed. A normalized TME structure was also observed, including angiogenesis suppression, antifibrotic effects and the inhibition of collagen formation in the tumor tissue, significantly enhancing the anti-tumor effects. In summary, this combination strategy may offer an alternative treatment for breast cancer.

Five-Stage Approach for a Systematic Screening and Development of Etravirine Amorphous Solid Dispersions by Hot-Melt Extrusion.

The aim of this study was to develop a fast, effective, and material sparing screening method to design amorphous solid dispersions (ASDs) of etravirine to drive more effectively the development process, leading to improved bioavailability (BA) and stability. A systematic step-by-step approach was followed by combining theoretical calculations with high-throughput screening (HTS) and software-assisted multivariate statistical analysis. The thermodynamic miscibility and interaction of the drug in several polymers were predicted using Hansen solubility parameters (δ). The selected polymers were evaluated by HTS, using solvent evaporation. Binary compositions were evaluated by their solubilization capacity and physical stability over 2 months. JMP 14.0 was used for multivariate statistical analysis using principal components analysis. Extrusion was performed in Thermo Scientific HAAKE MiniLab II, and extrudates were characterized by assay, related substances, dissolution, and physical state (polarized light microscopy (PLM), Raman spectroscopy, and X-ray powder diffraction (XRPD)). A short stability study was performed where milled extrudates were exposed to 25 °C/60%RH and 40 °C/75%RH for 3 months. Through thermodynamic predictions, five main polymers were selected. The HTS enabled the evaluation of 42 formulations for solubilization capacity and physical stability. The three most promising compositions were selected for hot-melt extrusion (HME) tests. In general, a good correlation was found among the results of theoretical predictions, HTS, and HME. Poly(vinylpyrrolidone) (PVP)-based formulations were shown to be easily extrudable, with low degradation and complete amorphicity, whereas in Soluplus, the drug was not miscible, leading to a high crystalline content. The drug release rate was improved more than two times with PVP, and the manufactured ASD was demonstrated to be stable physically and chemically. A fast and effective screening technique to develop stable ASDs for a poorly soluble drug was successfully developed as applied to etravirine. The given method is easy to use, requires a low amount of drug, and is fairly accurate in predicting the amorphization of the drug when formulated. The success of HME formulation development of etravirine was undoubtedly enhanced with this high-throughput tool, which led to the identification of extrudates with improved biopharmaceutical properties. The structural characterization performed by PLM, XRPD, and Raman spectroscopy demonstrated that the HME prototype was essentially amorphous. The unexpected stability at 40 °C/75%RH was correlated with the presence of molecular interaction characterized by Raman spectroscopy.

UPLC-MS/MS study of the effect of dandelion root extract on the plasma levels of the selected irreversible tyrosine kinase inhibitors dasatinib, imatinib and nilotinib in rats: Potential risk of pharmacokinetic interactions.

Tyrosine kinase inhibitor treatments for chronic myeloid leukaemia based on nilotinib (NIL), dasatinib (DAS) and imatinib (IMA) have improved patient quality of life and have turned chronic myeloid leukemia from a fatal disease into a chronic disease. Dandelion is a rich source of phenolic compounds with strong biological properties, and the effects of using this plant in the treatment of different illnesses can be linked to the presence of various polyphenols found in the different parts of the plant. Thus, dandelion can potentially be used as a nutraceutical (dietary antioxidant) to prevent different disorders associated with oxidative stress, i.e. cardiovascular disorders, cancer and inflammatory processes. Mutual interference between a drug and a food constituent may result in altered pharmacokinetics of the drug and undesired or even dangerous clinical situations. In the present study, a bioanalytical ultra performance liquid chromatography-tandem mass spectrometer (UPLC-MS/MS) method was developed and validated for the quantification of DAS, IMA and NIL in rat plasma. Sample preparation was carried out using solid-phase extraction with C18 cartridges with a good extraction recovery of ≥94.37% for the three drugs. The method was fully validated as per the US Food and Drug Administration guidelines.

Colorectal distribution and retention of polymeric nanoparticles following incorporation into a thermosensitive enema.

Nanotechnology-based systems have been proposed for rectal drug delivery, often rendering promising outcomes concerning disease prophylaxis or therapeutics. However, nanocarriers often feature reduced colorectal retention when administered in liquid vehicles (enemas). Semi-solid platforms may be considered as alternative but usually result in limited local distribution. Thermosensitive enemas undergoing sol-gel transition just below body temperature have been used for abbreviating these issues, but the actual impact on the colorectal distribution and retention of incorporated nanosystems is not clear. We prepared and characterized a potential drug delivery platform by incorporating poly(lactic-co-glycolic acid)-based nanoparticles (170-180 nm mean hydrodynamic diameter) into a poloxamer 407-based thermosensitive enema (NPs-in-thermo). The system featured suitable functional properties for rectal administration such as sol-gel transition temperature of approximately 27-28 °C, sol-gel transition time of 1.6 min, and viscosity around 31 and 2100 mPa s at 20 °C and 37 °C, respectively. NPs-in-thermo presented osmolality and pH values deemed compatible with the colorectal compartment, as well as reduced toxicity to the Caco-2 colorectal cell line. The composite system was also used to incorporate the anti-HIV microbicide model drug dapivirine. In vitro studies showed that dapivirine-loaded NPs-in-thermo was able to provide overall faster drug release as compared to dapivirine directly dispersed into phosphate buffered saline or the thermosensitive enema base. Finally, NPs-in-thermo was tested for distribution and retention in a mouse model by in vivo and ex vivo near infrared imaging. Qualitative and semi-quantitative data indicated that NPs exhibited slower but overall wider distribution and enhanced retention in the distal colon of mice treated intrarectally with NPs-in-thermo, namely when compared to NPs dispersed in liquid phosphate buffered saline. Overall, our data support that thermosensitive enemas may provide suitable platforms for the rectal administration of polymeric NPs, namely in the context of drug delivery.

ALK2 inhibitors display beneficial effects in preclinical models of ACVR1 mutant diffuse intrinsic pontine glioma.

Diffuse intrinsic pontine glioma (DIPG) is a lethal childhood brainstem tumour, with a quarter of patients harbouring somatic mutations in ACVR1, encoding the serine/threonine kinase ALK2. Despite being an amenable drug target, little has been done to-date to systematically evaluate the role of ACVR1 in DIPG, nor to screen currently available inhibitors in patient-derived tumour models. Here we show the dependence of DIPG cells on the mutant receptor, and the preclinical efficacy of two distinct chemotypes of ALK2 inhibitor in vitro and in vivo. We demonstrate the pyrazolo[1,5-a]pyrimidine LDN-193189 and the pyridine LDN-214117 to be orally bioavailable and well-tolerated, with good brain penetration. Treatment of immunodeprived mice bearing orthotopic xenografts of H3.3K27M, ACVR1R206H mutant HSJD-DIPG-007 cells with 25 mg/kg LDN-193189 or LDN-214117 for 28 days extended survival compared with vehicle controls. Development of ALK2 inhibitors with improved potency, selectivity and advantageous pharmacokinetic properties may play an important role in therapy for DIPG patients.

Plasma Protein Binding as an Optimizable Parameter for Acidic Drugs.

The low volume of distribution associated with acidic molecules means that clearance (CL) must also be very low to achieve an effective half-life commensurate with once or twice daily dosing. Plasma protein binding (PPB) should not usually be considered a parameter for optimization, but in the particular case of acidic molecules, raising the PPB above a certain level can result in distribution volume becoming a constant low value equal to the distribution volume of albumin while acting to reduce CL through restricting hepatic and renal access of unbound drug. Thus effective half-life can be increased. Here we detail the approaches and lessons learned at AstraZeneca during the optimization of acidic CXC chemokine receptor 2 (CXCR2) antagonists for the oral drug treatment of inflammatory diseases, resulting in discovery and clinical testing of N-[2-[(2,3-difluorophenyl)methylsulfanyl]-6-[(2R,3S)-3,4-dihydroxybutan-2-yl]oxypyrimidin-4-yl]azetidine-1-sulfonamide (AZD5069) and AZD4721, orally bioavailable acidic molecules with PPB of <1%, human hepatocyte intrinsic clearance values <5 µl/min per 106 cells and predicted human volume of distribution at steady state (V ss) <0.3 l/kg, resulting in effective half-lives in humans of 4 and 17 hours, respectively. SIGNIFICANCE STATEMENT: Provided that the pharmacologic potency is high enough, modulation of plasma protein binding can form part of a viable strategy in drug discovery to optimize the effective half-life of drug candidates in humans.

Preclinical Evaluation of a Novel TSPO PET Ligand 2-(7-Butyl-2-(4-(2-[18F]Fluoroethoxy)phenyl)-5-Methylpyrazolo[1,5-a]Pyrimidin-3-yl)-N,N-Diethylacetamide (18F-VUIIS1018A) to Image Glioma.

PURPOSE: There is an urgent need for the development of novel positron emission tomography (PET) tracers for glioma imaging. In this study, we developed a novel PET probe ([18F]VUIIS1018A) by targeting translocator protein (TSPO), an imaging biomarker for glioma. The purpose of this preclinical study was to evaluate this novel TSPO probe for glioma imaging. PROCEDURES: In this study, we synthesized [19F]VUIIS1018A and the precursor for radiosynthesis of [18F]VUIIS1018A. TSPO binding affinity was confirmed using a radioligand competitive binding assay in C6 glioma cell lysate. Further, dynamic imaging studies were performed in rats using a microPET system. These studies include displacement and blocking studies for ligand reversibility and specificity evaluation, and compartment modeling of PET data for pharmacokinetic parameter measurement using metabolite-corrected arterial input functions and PMOD. RESULTS: Compared to previously reported TSPO tracers including [18F]VUIIS1008 and [18F]DPA-714, the novel tracer [18F]VUIIS1018A demonstrated higher binding affinity and BPND. Pretreatment with the cold analog [19F]VUIIS1018A could partially block tumor accumulation of this novel tracer. Further, compartment modeling of this novel tracer also exhibited a greater tumor-to-background ratio, a higher tumor binding potential and a lower brain binding potential when compared with other TSPO probes, such as [18F]DPA-714 and [18F]VUIIS1008. CONCLUSIONS: These studies illustrate that [18F]VUIIS1018A can serve as a promising TSPO PET tracer for glioma imaging and potentially imaging of other solid tumors.

Safety and Tolerability of the Chymase Inhibitor Fulacimstat in Patients With Left Ventricular Dysfunction After Myocardial Infarction-Results of the CHIARA MIA 1 Trial.

The chymase inhibitor fulacimstat is developed as a first-in-class treatment option for the inhibition of adverse cardiac remodeling in patients with left ventricular dysfunction (LVD) after acute myocardial infarction (MI). The aim of the study was to examine the safety and tolerability of fulacimstat in patients with LVD after remote MI. A multicenter, multinational randomized, placebo-controlled study was performed in clinically stable patients (40-79 years of age, left ventricular ejection fraction ≤ 45% because of MI in medical history) who were on stable evidence-based standard-of-care therapies for LVD post-MI including an angiotensin converting enzyme inhibitor or angiotensin receptor blocker at doses of at least half the recommended target dose. Patients were treated for 2 weeks with either placebo (n = 12) or 4 different doses of fulacimstat (5 mg twice daily, n = 9; 10 mg twice daily, n = 9; 25 mg twice daily, n = 10; 50 mg once daily, n = 9). Fulacimstat was safe and well tolerated at all examined doses. There were no clinically relevant effects on vital signs or potassium levels compared with placebo treatment. Mean plasma concentrations of fulacimstat increased with the administered dose and reached exposures predicted to be therapeutically active. The safety profile and the absence of effects on blood pressure or heart rate in a chronic patient population having similar comorbidities and receiving similar comedication as patients after acute MI support future clinical trials with fulacimstat in patients after acute MI.

Phase 1b trial of an ibrutinib-based combination therapy in recurrent/refractory CNS lymphoma.

Ibrutinib is a first-in-class inhibitor of Bruton tyrosine kinase (BTK) and has shown single-agent activity in recurrent/refractory central nervous system (CNS) lymphoma. Clinical responses are often transient or incomplete, suggesting a need for a combination therapy approach. We conducted a phase 1b clinical trial to explore the sequential combination of ibrutinib (560 or 840 mg daily dosing) with high-dose methotrexate (HD-MTX) and rituximab in patients with CNS lymphoma (CNSL). HD-MTX was given at 3.5 g/m2 every 2 weeks for a total of 8 doses (4 cycles; 1 cycle = 28 days). Ibrutinib was held on days of HD-MTX infusion and resumed 5 days after HD-MTX infusion or after HD-MTX clearance. Single-agent daily ibrutinib was administered continuously after completion of induction therapy until disease progression, intolerable toxicity, or death. We also explored next-generation sequencing of circulating tumor DNA (ctDNA) in cerebrospinal fluid (CSF) before and during treatment. The combination of ibrutinib, HD-MTX, and rituximab was tolerated with an acceptable safety profile (no grade 5 events, 3 grade 4 events). No dose-limiting toxicity was observed. Eleven of 15 patients proceeded to maintenance ibrutinib after completing 4 cycles of the ibrutinib/HD-MTX/rituximab combination. Clinical responses occurred in 12 of 15 patients (80%). Sustained tumor responses were associated with clearance of ctDNA from the CSF. This trial was registered at www.clinicaltrials.gov as #NCT02315326.

Risdiplam distributes and increases SMN protein in both the central nervous system and peripheral organs.

Spinal muscular atrophy (SMA) is a rare, inherited neuromuscular disease caused by deletion and/or mutation of the Survival of Motor Neuron 1 (SMN1) gene. A second gene, SMN2, produces low levels of functional SMN protein that are insufficient to fully compensate for the lack of SMN1. Risdiplam (RG7916; RO7034067) is an orally administered, small-molecule SMN2 pre-mRNA splicing modifier that distributes into the central nervous system (CNS) and peripheral tissues. To further explore risdiplam distribution, we assessed in vitro characteristics and in vivo drug levels and effect of risdiplam on SMN protein expression in different tissues in animal models. Total drug levels were similar in plasma, muscle, and brain of mice (n = 90), rats (n = 148), and monkeys (n = 24). As expected mechanistically based on its high passive permeability and not being a human multidrug resistance protein 1 substrate, risdiplam CSF levels reflected free compound concentration in plasma in monkeys. Tissue distribution remained unchanged when monkeys received risdiplam once daily for 39 weeks. A parallel dose-dependent increase in SMN protein levels was seen in CNS and peripheral tissues in two SMA mouse models dosed with risdiplam. These in vitro and in vivo preclinical data strongly suggest that functional SMN protein increases seen in patients' blood following risdiplam treatment should reflect similar increases in functional SMN protein in the CNS, muscle, and other peripheral tissues.