Adjusting Catalytic Activity of ß-Amyrin Synthase GgBAS by Utilizing the Plasticity Residues of an Active Site.

ß-Amyrin synthase (bAS) is a representative plant oxidosqualene cyclase (OSC), and previous studies have identified many functional residues and mutants that can alter its catalytic activity. However, the regulatory mechanism of the active site architecture for adjusting the catalytic activity remains unclear. In this study, we investigate the function of key residues and their regulatory effects on the catalytic activity of Glycyrrhiza glabra ß-amyrin synthase (GgbAS) through molecular dynamics simulations and site-directed mutagenesis experiments. We identified the plasticity residues located in two active site regions and explored the interactions between these residues and tetracyclic/pentacyclic intermediates. Based on computational and experimental results, we further categorize these plasticity residues into three types: effector, adjuster, and supporter residues, according to their functions in the catalytic process. This study provides valuable insights into the catalytic mechanism and active site plasticity of GgbAS, offering important references for the rational enzyme engineering of other OSC enzyme.

NIMO: A Natural Product-Inspired Molecular Generative Model Based on Conditional Transformer.

Natural products (NPs) have diverse biological activity and significant medicinal value. The structural diversity of NPs is the mainstay of drug discovery. Expanding the chemical space of NPs is an urgent need. Inspired by the concept of fragment-assembled pseudo-natural products, we developed a computational tool called NIMO, which is based on the transformer neural network model. NIMO employs two tailor-made motif extraction methods to map a molecular graph into a semantic motif sequence. All these generated motif sequences are used to train our molecular generative models. Various NIMO models were trained under different task scenarios by recognizing syntactic patterns and structure-property relationships. We further explored the performance of NIMO in structure-guided, activity-oriented, and pocket-based molecule generation tasks. Our results show that NIMO had excellent performance for molecule generation from scratch and structure optimization from a scaffold.

A chemoinformatic analysis on natural glycosides with respect to biological origin and structural class.

Covering: up to 202216.19% of reported natural products (NPs) in the Dictionary of Natural Products (DNP) are glycosides. As one of the most important NPs' structural modifications, glycosylation can change the NPs' polarity, making the aglycones more amphipathic. However, until now, little is known about the general distribution profile of the natural glycosides in different biological sources or structural types. The reason, structural or species preferences of the natural glycosylation remain unclear. In this highlight, chemoinformatic methods were employed to analyze the natural glycosides from DNP, the most comprehensively annotated NP database. We found that the glycosylation ratios of NPs from plants, bacteria, animals and fungi decrease successively, which are 24.99%, 20.84%, 8.40% and 4.48%, respectively. Echinoderm-derived NPs (56.11%) are the most frequently glycosylated, while those produced by molluscs (1.55%), vertebrates (2.19%) and Rhodophyta (3.00%) are the opposite. Among the diverse structural types, a large proportion of steroids (45.19%), tannins (44.78%) and flavonoids (39.21%) are glycosides, yet aminoacids and peptides (5.16%), alkaloids (5.66%) are comparatively less glycosylated. Even within the same biological source or structural type, their glycosylation rates fluctuate drastically between sub- or cross-categories. The substitute patterns of flavonoid and terpenoid glycosides and the most frequently glycosylated scaffolds were identified. NPs with different glycosylation levels occupy different chemical spaces of physicochemical property and scaffold. These findings could help us to interpret the preference of NPs' glycosylation and investigate how NP glycosylation could aid NP-based drug discovery.

Molecular dynamic simulations identifying the mechanism of holoenzyme formation by O-GlcNAc transferase and active p38α.

O-N-Acetylglucosamine transferase (OGT) can catalyze the O-GlcNAc modification of thousands of proteins. The holoenzyme formation of OGT and adaptor protein is the precondition for further recognition and glycosylation of the target protein, while the corresponding mechanism is still open. Here, static and dynamic schemes based on statistics can successfully screen the feasible identifying, approaching, and binding mechanism of OGT and its typical adaptor protein p38α. The most favorable interface, energy contribution of hotspots, and conformational changes of fragments were discovered. The hydrogen bond interactions were verified as the main driving force for the whole process. The distinct characteristic of active and inactive p38α is explored and demonstrates that the phosphorylated tyrosine and threonine will form strong ion-pair interactions with Lys714, playing a key role in the dynamic identification stage. Multiple method combinations from different points of view may be helpful for exploring other systems of the protein-protein interactions.

Results of a phase 2, multicenter, single-arm, open-label study of lenalidomide in pediatric patients with relapsed or refractory acute myeloid leukemia.

BACKGROUND: Outcomes after relapse remain poor in pediatric patients with acute myeloid leukemia (AML), and new therapeutic approaches are needed. Lenalidomide has demonstrated activity in adults with lower risk myelodysplastic syndromes and older adults with relapsed or refractory (R/R) AML. METHODS: In this phase 2 study (NCT02538965), pediatric patients with R/R AML who received two or more prior therapies were treated with lenalidomide (starting dose 2 mg/kg/day on days 1-21 of each 28-day cycle) for a maximum of 12 cycles. The primary endpoint was rate of complete response (CR) and CR with incomplete blood count recovery (CRi) within the first four cycles. RESULTS: Seventeen patients enrolled and received one or more dose of lenalidomide. Median age was 12 years (range 5-18 years), median white blood cell count was 3.7 × 109 /L, and median peripheral blood blast count was 1.0 × 109 /L. One patient (5.9%) with a complex karyotype including del(5q) achieved CRi after two cycles of lenalidomide. This responder proceeded to a second hematopoietic stem cell transplantation and has remained without evidence of disease for 3 years. All patients experienced one or more of grades 3-4 treatment-emergent adverse event (TEAE). The most common grades 3-4 TEAEs were thrombocytopenia (58.8%), febrile neutropenia (47.1%), anemia (41.2%), and hypokalemia (41.2%). CONCLUSIONS: In this population of pediatric patients with R/R AML, safety data were consistent with the known safety profile of lenalidomide. As only one patient responded, further evaluation of lenalidomide at the dose and schedule studied is not warranted in pediatric AML, with the possible exception of patients with del(5q).

Accelerating the identification of subtype selective inhibitors via Three-Dimensional Biologically Relevant Spectrum (BRS-3D): The monoamine oxidase subtypes as a case study.

Subtype-selective drugs are of great therapeutic importance as they are expected to be more effective and with less side-effects. However, discovery of subtype selective inhibitors was hampered by the high similarity of the binding sites within subfamilies. In this study, we further evaluated the applicability of "Three-Dimensional Biologically Relevant Spectrum (BRS-3D)" for the identification of subtype-selective inhibitors. A case study was performed on monoamine oxidase, which has two subtypes related to distinct diseases. The inhibitory activity against MAO-A/B of 347 compounds experimentally tested in this research was reported. Compound M124 (5H-thiazolo[3,2-a]pyrimidin-5-one) with IC50 less than 100 nM (SI = 23) was selected as a probe to investigate the structure selectivity relationship. Similarity search led to the identification of compound M229 and M249 with IC50 values of 7.4 nM, 4 nM and acceptable selectivity index over MAO-A (M229 SI > 1351, M249 SI > 2500). The molecular basis for subtype selectivity was explored through docking study and attention based DNN model. Additionally, in silico ADME properties were characterized. Accordingly, it is found that BRS-3D is a robust method for subtype selectivity in the early stage of drug discovery and the compounds reported here can be promising leads for further experimental analysis.

Neonatal Fc Receptor (FcRn) Enhances Tissue Distribution and Prevents Excretion of nab-Paclitaxel.

nab-Paclitaxel ( nab-P), an albumin-bound formulation of paclitaxel, was developed to improve the tolerability and antitumor activity of taxanes. The neonatal Fc receptor (FcRn) is a transport protein that can bind to albumin and regulate the homeostasis of circulating albumin. Therefore, the pharmacokinetics and pharmacodynamics of nab-P may be impacted by FcRn expression. This study aimed to investigate the effects of FcRn on nab-P elimination and distribution to targeted tissues. Wild-type and FcRn-knockout (FcRn-KO) mice were treated with nab-P, mouse-specific nab-P (distribution experiments only), and solvent-based paclitaxel (pac-T). Blood and tissue samples were collected for distribution analyses. Organ, urine, and fecal samples were collected for elimination analyses. The nab-P tissue penetration in the pancreas, fat pad, and kidney of wild-type mice, as reflected by the ratio of tissue/plasma concentration, was significantly higher (ranging from 5 to 80 fold) than that of FcRn-KO mice. In contrast, the tissue penetration of pac-T in these organs of FcRn-KO mice was similar to that of wild-type mice. More importantly, the excretion of nab-P in feces of FcRn-KO mice (45-68%) was significantly higher than that of wild-type mice (26-46%) from 8 to 48 h post treatment. In comparison, the difference of excretion of pac-T in feces between FcRn-KO mice and wild-type mice was smaller than that of nab-P. Furthermore, greater tissue penetration and fecal excretion were observed with nab-P than pac-T in both FcRn-KO and wild-type mice. These findings suggest that FcRn enhances the tissue distribution and penetration of nab-P in the targeted organs, while FcRn prevents excretion of nab-P to feces in the intestinal lumen. The findings support the notion that albumin nanoparticle delivery alters drug distribution and elimination through an FcRn-mediated process to impact drug efficacy and toxicity.

Novel C7-Substituted Coumarins as Selective Monoamine Oxidase Inhibitors: Discovery, Synthesis and Theoretical Simulation.

There is a continued need to develop new selective human monoamine oxidase (hMAO) inhibitors that could be beneficial for the treatment of neurological diseases. However, hMAOs are closely related with high sequence identity and structural similarity, which hinders the development of selective MAO inhibitors. "Three-Dimensional Biologically Relevant Spectrum (BRS-3D)" method developed by our group has demonstrated its effectiveness in subtype selectivity studies of receptor and enzyme ligands. Here, we report a series of novel C7-substituted coumarins, either synthesized or commercially purchased, which were identified as selective hMAO inhibitors. Most of the compounds demonstrated strong activities with IC50 values (half-inhibitory concentration) ranging from sub-micromolar to nanomolar. Compounds, FR1 and SP1, were identified as the most selective hMAO-A inhibitors, with IC50 values of 1.5 nM (selectivity index (SI) < -2.82) and 19 nM (SI < -2.42), respectively. FR4 and FR5 showed the most potent hMAO-B inhibitory activity, with IC50 of 18 nM and 15 nM (SI > 2.74 and SI > 2.82). Docking calculations and molecular dynamic simulations were performed to elucidate the selectivity preference and SAR profiles.

Different Nanoformulations Alter the Tissue Distribution of Paclitaxel, Which Aligns with Reported Distinct Efficacy and Safety Profiles.

Previous studies have shown that different paclitaxel formulations produce distinct anticancer efficacy and safety profiles in animals and humans. This study aimed to investigate the distinct pharmacokinetics and tissue distribution of various nanoformulations of paclitaxel, which may translate into potential differences in safety and efficacy. Four nanoparticle formulations ( nab-paclitaxel, mouse albumin nab-paclitaxel [m -nab-paclitaxel], micellar paclitaxel, and polymeric nanoparticle paclitaxel) as well as solvent-based paclitaxel were intravenously administered to mice. Seventeen blood and tissue samples were collected at different time points. The total paclitaxel concentration in each tissue specimen was measured with liquid chromatography-tandem mass spectrometry. Compared with solvent-based paclitaxel, all four nanoformulations demonstrated decreased paclitaxel exposure in plasma. All nanoformulations were associated with paclitaxel blood-cell accumulation in mice; however, m- nab-paclitaxel was associated with the lowest accumulation. Five minutes after dosing, the total paclitaxel in the tissues and blood was approximately 44% to 57% of the administered dose of all paclitaxel formulations. Paclitaxel was primarily distributed to liver, muscle, intestine, kidney, skin, and bone. Compared with solvent-based paclitaxel, the different nanocarriers altered the distribution of paclitaxel in all tissues with distinct paclitaxel concentration-time profiles. nab-paclitaxel was associated with increased delivery efficiency of paclitaxel in the pancreas compared with the other formulations, consistent with the demonstrated efficacy of nab-paclitaxel in pancreatic cancer. All the nanoformulations led to high penetration in the lungs and fat pad, which potentially points to efficacy in lung and breast cancers. Micellar paclitaxel and polymeric nanoparticle paclitaxel were associated with high paclitaxel accumulation in the heart; thus, the risk of cardiovascular toxicity with these formulations may warrant further investigation. The solvent-based formulation was associated with the poorest paclitaxel penetration in all tissues and the lowest tissue-to-plasma ratio. The different nanocarriers of paclitaxel were associated with distinct pharmacokinetics and tissue distribution, which largely align with the observed efficacy and toxicity profiles in clinical trials.

Phase 1b study of the mammalian target of rapamycin inhibitor sirolimus in combination with nanoparticle albumin-bound paclitaxel in patients with advanced solid tumors.

BACKGROUND: The optimal weekly oral dose of sirolimus and intravenous nanoparticle albumin-bound paclitaxel (nab-paclitaxel) were evaluated. METHODS: A phase 1b study was performed to evaluate escalating doses of oral sirolimus (5-60 mg) on days 2, 9, and 16 with intravenous nab-paclitaxel (100 mg/m(2) ) on days 1, 8, and 15 in a 28-day cycle. A run-in treatment of nab-paclitaxel (day -14) and sirolimus (day -7) was administered for pharmacokinetic and pharmacodynamic assessments. Clinical trial endpoints included dose-limiting toxicities (DLTs), maximum tolerated doses, and response rates. Pharmacodynamics included immunohistochemistry for phosphatase and tensin homolog, mammalian target of rapamycin (mTOR), AKT, phosphorylated AKT, S6K1, and phosphorylated S6K1; exploratory gene expression analysis; and [(18) F]fludeoxyglucose (FDG) positron emission tomography. RESULTS: Twenty-three patients with advanced solid tumors were treated. Fifteen patients had prior taxane therapy. Twenty-two patients were evaluable for responses. One patient had a complete response, and 5 patients had a partial response (3 confirmed). DLTs were seen in 1 patient each at 10 (grade 3 dyspnea/hypoxia) and 40 mg (grade 4 leukopenia/neutropenia) and in 2 patients at 60 mg (grade 3 fatigue and grade 4 pericardial effusion). Patients with higher expression of posttreatment AKT and a greater decline in FDG activity were more likely to have a treatment response or stable disease. CONCLUSIONS: Sirolimus showed an acceptable safety profile at a weekly dose of 40 mg with weekly intravenous nab-paclitaxel at 100 mg/m(2) on days 1, 8, and 15 every 28 days. The posttreatment AKT score and changes in FDG activity may have roles as early predictors of responses to mTOR inhibitors.

Pharmacologic sensitivity of paclitaxel to its delivery vehicles drives distinct clinical outcomes of paclitaxel formulations.

Paclitaxel, an effective antitumor agent, is formulated in various vehicles serving as carriers to deliver the hydrophobic paclitaxel to tissue. The approved formulations in the U.S. are paclitaxel formulated in Cremophor EL (currently known as Kolliphor EL) and nanoparticle albumin-bound paclitaxel (nab-paclitaxel). Despite having the same active ingredient (paclitaxel), different formulations produce distinct products with unique efficacy and safety profiles. A semimechanistic model was developed to describe the pharmacologic sensitivity of paclitaxel under different formulations. Circulating paclitaxel concentration data from patients treated with nab-paclitaxel or Cremophor EL-paclitaxel were analyzed in NONMEM using a semimechanistic model with simultaneous disposition of paclitaxel-carrier complexes and the total paclitaxel released from the complexes. The key factors driving paclitaxel exposure in circulation and peripheral tissues were explored via sensitivity analysis. The rapid decline of total paclitaxel concentration following intravenous administration of nab-paclitaxel and Cremophor EL-paclitaxel was attributed to rapid tissue distribution of the paclitaxel-carrier complexes, with minor contribution of free and protein-bound paclitaxel. Distribution of nab-paclitaxel to peripheral tissue was 4-fold faster and 10-fold more extensive than that of Cremophor EL-paclitaxel micelles, resulting in distinct tissue paclitaxel profiles. Sensitivity analyses showed the plasma paclitaxel-time profile was insensitive to the rapid rates of tissue distribution and decomposition of paclitaxel-carrier complexes but that the tissue distribution profile of paclitaxel was highly sensitive. Tissue distribution of paclitaxel is carrier complex system-dependent. Different delivery systems result in distinct tissue paclitaxel profiles but similar paclitaxel concentration-time profiles in plasma or blood, rendering the paclitaxel plasma profile a poor surrogate for its clinical outcome.

Combined treatment with lenalidomide and epoetin alfa in lower-risk patients with myelodysplastic syndrome.

The erythropoietic effects of lenalidomide are cytokine dependent, suggesting that the erythroid hematologic improvement (HI-E) rate may be augmented by combined treatment (CT) with recombinant human erythropoietin (rhu-EPO) in myelodysplastic syndrome (MDS). In the present study, we explored the benefits of CT and the relationship between lenalidomide pharmacokinetics and hematologic toxicity in transfusion-dependent patients with low- to intermediate-1-risk MDS who failed prior rhu-EPO. In stage I, patients received 10 or 15 mg/d of lenalidomide monotherapy. At week 16, erythroid nonresponders (NRs) were eligible for CT with rhu-EPO 40 000 U/wk. Among 39 patients, HI-E response rate to monotherapy was 86% (6 of 7) in del(5q) and 25% (8 of 32) in non-del(5q) patients (10 mg, 17.7%; 15 mg, 33.3%). Twenty-three patients proceeded to CT, with 6 (26.0%) achieving HI-E. In 19 non-del(5q) patients, 4 (21.1%) showed HI-E. Mean baseline serum EPO in non-del(5q) patients was lower in monotherapy and CT responders than in NR (not statistically significant). Thrombocytopenia was significantly correlated with lenalidomide area under the plasma concentration-time curve (P = .0015), but severity of myelosuppression did not. The benefits of lenalidomide plus rhu-EPO are currently under investigation in a phase 3 Eastern Cooperative Oncology Group (ECOG)-sponsored intergroup study. This study is registered at www.clinicaltrials.gov as NCT00910858.

Discovery of a SUCNR1 antagonist for potential treatment of diabetic nephropathy: In silico and in vitro studies.

Diabetic nephropathy (DN) is one of the most severe complications of diabetes mellitus. Succinate Receptor 1 (SUCNR1), a member of the G-protein-coupled receptor (GPCR) family, represents a potential target for treatment of DN. Here, utilizing multi-strategy in silico virtual screening methods containing AlphaFold2 modelling, molecular dynamics (MD) simulation, ligand-based pharmacophore screening, molecular docking and machine learning-based similarity clustering, we successfully identified a novel antagonist of SUCNR1, AK-968/12117473 (Cpd3). Through extensive in vitro experiments, including dual-luciferase reporter assay, cellular thermal shift assay, immunofluorescence, and western blotting, we substantiated that Cpd3 could specifically target SUCNR1, inhibit the activation of NF-κB pathway, and ameliorate epithelial-mesenchymal transition (EMT) and extracellular matrix (ECM) deposition in renal tubular epithelial cells (NRK-52E) under high glucose conditions. Further in silico simulations revealed the molecular basis of the SUCNR1-Cpd3 interaction, and the in vitro metabolic stability assay indicated favorable drug-like pharmacokinetic properties of Cpd3. This work not only successfully pinpointed Cpd3 as a specific antagonist of SUCNR1 to serve as a promising candidate in the realm of therapeutic interventions for DN, but also provides a paradigm of dry-wet combined discovery strategies for GPCR-based therapeutics.

Developing TeroENZ and TeroMAP modules for the terpenome research platform TeroKit.

Terpenoids and their derivatives are collectively known as the terpenome and are the largest class of natural products, whose biosynthesis refers to various kinds of enzymes. To date, there is no terpenome-related enzyme database, which is a desire for enzyme mining, metabolic engineering and discovery of new natural products related to terpenoids. In this work, we have constructed a comprehensive database called TeroENZ (http://terokit.qmclab.com/browse_enz.html) containing 13 462 enzymes involved in the terpenoid biosynthetic pathway, covering 2541 species and 4293 reactions reported in the literature and public databases. At the same time, we classify enzymes according to their catalytic reactions into cyclase, oxidoreductase, transferase, and so on, and also make a classification according to species. This meticulous classification is beneficial for users as it can be retrieved and downloaded conveniently. We also provide a computational module for isozyme prediction. Moreover, a module named TeroMAP (http://terokit.qmclab.com/browse_rxn.html) is also constructed to organize all available terpenoid enzymatic reactions into an interactive network by interfacing with the previously established database of terpenoid compounds, TeroMOL. Finally, all these databases and modules are integrated into the web server TeroKit (http://terokit.qmclab.com/) to shed light on the field of terpenoid research. Database URL http://terokit.qmclab.com/.

Aiding early clinical drug development by elucidation of the relationship between tumor growth inhibition and survival in relapsed/refractory multiple myeloma patients.

Early prognosis of clinical efficacy is an urgent need for oncology drug development. Herein, we systemically examined the quantitative approach of tumor growth inhibition (TGI) and survival modeling in the space of relapsed and refractory multiple myeloma (MM), aiming to provide insights into clinical drug development. Longitudinal serum M-protein and progression-free survival (PFS) data from three phase III studies (N = 1367) across six treatment regimens and different patient populations were leveraged. The TGI model successfully described the longitudinal M-protein data in patients with MM. The tumor inhibition and growth parameters were found to vary as per each study, likely due to the patient population and treatment regimen difference. Based on a parametric time-to-event model for PFS, M-protein reduction at week 4 was identified as a significant prognostic factor for PFS across the three studies. Other factors, including Eastern Cooperative Oncology Group performance status, prior anti-myeloma therapeutics, and baseline serum ß2-microglobulin level, were correlated with PFS as well. In conclusion, patient disease characteristics (i.e., baseline tumor burden and treatment lines) were important determinants of tumor inhibition and PFS in MM patients. M-protein change at week 4 was an early prognostic biomarker for PFS.

Predicting lung adenocarcinoma disease progression using methylation-correlated blocks and ensemble machine learning classifiers.

Applying the knowledge that methyltransferases and demethylases can modify adjacent cytosine-phosphorothioate-guanine (CpG) sites in the same DNA strand, we found that combining multiple CpGs into a single block may improve cancer diagnosis. However, survival prediction remains a challenge. In this study, we developed a pipeline named "stacked ensemble of machine learning models for methylation-correlated blocks" (EnMCB) that combined Cox regression, support vector regression (SVR), and elastic-net models to construct signatures based on DNA methylation-correlated blocks for lung adenocarcinoma (LUAD) survival prediction. We used methylation profiles from the Cancer Genome Atlas (TCGA) as the training set, and profiles from the Gene Expression Omnibus (GEO) as validation and testing sets. First, we partitioned the genome into blocks of tightly co-methylated CpG sites, which we termed methylation-correlated blocks (MCBs). After partitioning and feature selection, we observed different diagnostic capacities for predicting patient survival across the models. We combined the multiple models into a single stacking ensemble model. The stacking ensemble model based on the top-ranked block had the area under the receiver operating characteristic curve of 0.622 in the TCGA training set, 0.773 in the validation set, and 0.698 in the testing set. When stratified by clinicopathological risk factors, the risk score predicted by the top-ranked MCB was an independent prognostic factor. Our results showed that our pipeline was a reliable tool that may facilitate MCB selection and survival prediction.

Population Pharmacokinetics and Exposure-Response Analysis of nab-Paclitaxel in Pediatric Patients With Recurrent or Refractory Solid Tumors.

Pediatric malignancies are most commonly of primary central nervous system or hematopoietic origin. The main reason for cancer death in pediatrics is refractory and relapsed disease, and improved therapeutic options are needed in the pediatric population. Nanoparticle albumin-bound (nab)-paclitaxel (Abraxane) is a human albumin-stabilized formulation of paclitaxel and was designed to improve the chemotherapeutic effects of paclitaxel and to reduce toxicities. Although nab-paclitaxel pharmacokinetics (PK) has been extensively studied in adults, no information is available on its PK in children. ABI-007-PST-001 was the first nab-paclitaxel clinical trial conducted in pediatrics, and the current analysis is the first study of nab-paclitaxel PK in pediatrics. Our analyses suggested that ontogeny and maturation play a role in nab-paclitaxel PK disposition, as demonstrated by the finding that both blood clearance and volume of distribution increased from younger to older pediatric age groups and from pediatrics to adults. A 3-compartment population PK (PPK) model with saturable elimination was developed to describe the paclitaxel whole blood concentrations in pediatrics. The PPK model was customized by estimating the allometric function on PK parameters to take into account the ontogeny/maturation of patients. PPK estimates are consistent with the fast and deep distribution of paclitaxel that was previously observed in adults. Finally, the exposure-safety analysis showed an increased probability of drug-related adverse events (>grade 2) in cycle 1 and the first cycle of neutropenia (>grade 2) associated with higher doses. However, there is no statistically significant association between exposures (measured by area under the concentration-time curve) and the probabilities of either safety event.

First-in-Human, Single- and Multiple-Ascending-Dose Studies in Healthy Subjects to Assess Pharmacokinetics, Pharmacodynamics, and Safety/Tolerability of Iberdomide, a Novel Cereblon E3 Ligase Modulator.

Pharmacokinetics, pharmacodynamics, and safety/tolerability of iberdomide (CC-220), a highly potent oral cereblon E3 ligase modulator (CELMoD), were evaluated in escalating single-dose (0.03, 0.1, 0.3, 1, 2, 4, 6 mg) and multiple-dose (0.3 mg once daily for 14 days, 1 mg once daily for 28 days, 0.3 mg once daily for 28 days, or 1 mg once daily for 7 days with a 7-day washout, then once daily for 7 more days) studies in healthy subjects (n = 99). Iberdomide exposure increased in a dose-proportional manner. Terminal half-life was 9-13 hours after a single dose. Iberdomide decreased peripheral CD19+ B lymphocytes (Emax , 92.4%; EC50 , 0.718 ng/mL), with modest reductions in CD3+ T lymphocytes (Emax , 34.8%; EC50 , 0.932 ng/mL). Lipopolysaccharide-stimulated proinflammatory cytokines (IL-1α, IL-1ß) were reduced, but anti-CD3-stimulated IL-2 and interferon-γ were increased. Iberdomide 1 mg once daily partially decreased T-cell-independent antibody responses to PPV23 but did not change tetanus toxoid recall response. Pharmacodynamic data suggest dose-dependent, differential immunomodulatory effects on B and T lymphocytes. Iberdomide was tolerated up to 6 mg as a single dose and at 0.3 mg once daily for 4 weeks. Grade 3 asymptomatic neutropenia was observed following 1 mg once daily for 21 days; a 7-day drug holiday alleviated neutropenia. Further investigation of iberdomide in autoimmune and hematological diseases is warranted.

Population Pharmacokinetics and Exposure-Response Relationship of Luspatercept, an Erythroid Maturation Agent, in Anemic Patients With ß-Thalassemia.

ß-Thalassemia is an inherited blood disorder resulting from defects in hemoglobin production, leading to premature death of red blood cells (RBCs) or their precursors. Patients with transfusion-dependent ß-thalassemia often need lifelong regular RBC transfusions to maintain adequate hemoglobin levels. Frequent transfusions may lead to iron overload and organ damage. Thus, there is a large unmet need for alternative therapies. Luspatercept, a first-in-class erythroid maturation agent, is the first approved therapy in the United States for the treatment of anemia in adult patients with ß-thalassemia who require regular RBC transfusions. The population pharmacokinetics and exposure-response relationship of luspatercept were evaluated in 285 patients with ß-thalassemia. Luspatercept displayed linear and time-invariant pharmacokinetics when administered subcutaneously once every 3 weeks. Body weight was the only clinically relevant covariate of luspatercept clearance, favoring weight-based dosing. Magnitude and frequency of hemoglobin increase, if not influenced by RBC transfusions, was positively correlated with luspatercept area under the serum concentration-time curve (AUC), 0.2-1.25 mg/kg, whereas a significant reduction in RBC units transfused was observed in frequently transfused patients. The probability of achieving ≥33% or ≥50% reduction in RBC transfusion burden was similar across the time-averaged AUC (0.6-1.25 mg/kg), with the 1 mg/kg starting dose sufficient for most early responders (71%-80%). Increasing luspatercept AUC (0.2-1.25 mg/kg) did not increase incidence or severity of treatment-emergent adverse events. These results provide a positive benefit-risk profile for the recommended luspatercept doses (1-1.25 mg/kg) in treating adult patients with ß-thalassemia who require regular RBC transfusions.

Interrelation of dopamine transporter oligomerization and surface presence as studied with mutant transporter proteins and amphetamine.

Our previous work suggested a role for oligomerization in regulating dopamine transporter (DAT) internalization, with d-amphetamine dissociating DAT oligomers and monomers being endocytosed. This model was put to detailed testing in the present work with the use of DAT constructs differentially tagged with Myc or Flag, reversal of tags in co-immunoprecipitation and cross-linking assays, and application of antibodies against different tags in biotinylation experiments. Upon pairing wild-type (WT) DAT with W84L mutant, effects of d-amphetamine on oligomerization (decrease) but not surface DAT are observed. Internalization of W84L monomers appears to be slow as inferred from the inability of d-amphetamine to reduce surface Myc upon co-expressing Flag-WT with Myc-W84L but not Myc-WT with Flag-W84L, and from the sluggish Myc-W84L endocytosis rate (both with or without d-amphetamine). Results obtained for D313N, D345N, or D436N mutants can all be accommodated by a model in which D-amphetamine is unable to dissociate mutant protomers from oligomers (tetramers or higher-order assemblies) that contain them; this interpretation is confirmed in experiments with both tag reversal in co-expression and antibody reversal in western blotting. Upon co-transfecting Myc- and Flag-tagged constructs, resulting tetramers can be calculated to be composed of different species (MycMycMycMyc, MycMycMycFlag, MycMycFlagFlag, MycFlagFlagFlag, and FlagFlagFlagFlag), but it is shown that outcomes predicted by models based on MycMycFlagFlag oligomers are not changed in a major way by the occurrence of the additional species.