Time-varying brentuximab vedotin pharmacokinetics and weight-based dosing in paediatric patients despite lower exposure in those aged 2 to <6 and 6-11 years.

AIMS: We studied the pharmacokinetics and exposure-response relationships of the brentuximab vedotin (BV) antibody-drug conjugate (ADC) and unconjugated monomethyl auristatin E in haematologic malignancies. METHODS: This population pharmacokinetic analysis included data from five adult and three paediatric studies. Exposures in virtual adult and paediatric populations following BV 1.8 mg/kg (maximum 180 mg) intravenously every 3 weeks were simulated. Clinical endpoints included overall response rate, grade ≥2 peripheral neuropathy (PN) and grade ≥3 neutropenia. RESULTS: BV ADC exhibited linear pharmacokinetics, well-described by a three-compartment model, with body weight being the only significant covariate for exposure. Monomethyl auristatin E exhibited time-varying formation rate. Simulated steady-state BV ADC exposures in patients aged 12 to <18 years were similar to those of adult patients, but 23%-38% lower in patients aged 2 to <12 years. Despite lower exposure, clinical activity was observed with BV 1.8 mg/kg every 3 weeks in those aged 2 to <12 years (overall response rate: 2 to <12 years, 60%; 12 to <18 years, 43%). In adult, but not paediatric patients, increased BV ADC exposures were associated with grade ≥2 PN and grade ≥3 neutropenia occurrence. CONCLUSIONS: BV pharmacokinetics in adult and paediatric patients were consistent. BV ADC exposures were lower in patients aged 2 to <12 years vs. ≥12 years, but no apparent clinically relevant differences in efficacy, grade ≥2 PN or grade ≥3 neutropenia were observed. These data support body weight-based dosing of BV in patients irrespective of age; thus, dose adjustment in those 2 to <12 years does not appear warranted.

Exposure-Response and Subgroup Analyses to Support Body Weight-Based Dosing of Brentuximab Vedotin in Children and Young Adults with Newly Diagnosed High-Risk Classical Hodgkin Lymphoma.

PURPOSE: To evaluate the relationships between brentuximab vedotin (BV) pharmacokinetics, age, and body weight (BW) with efficacy and safety in pediatric and young adult patients with previously untreated, high-risk classical Hodgkin lymphoma (cHL) in the phase 3 AHOD1331 study. PATIENTS AND METHODS: Overall, 296 patients (age 2-21 years) in the overall population were randomized to and received BV + chemotherapy; the pharmacokinetic subpopulation comprised 24 patients (age <13 years). Age- and/or BW-based (pharmacokinetic surrogates) subgroup analyses of efficacy and safety were conducted for the overall population. Exposure-response analyses were limited to the pharmacokinetic subpopulation. RESULTS: There were no visible trends in disease characteristics across pediatric age subgroups, while BW increased with age. Observed antibody-drug conjugate exposures in patients aged <12 years were lower than those in adults administered BV 1.8 mg/kg every 3 weeks (Q3W), as exposure increased with BW. Nevertheless, no detrimental impact on event-free survival (EFS) was seen in younger subgroups: 3-year EFS was 96.2% (2-<12-years) and 92.0% (12-<18-years), with no events observed in those aged <6 years. Neither early response nor lack of need for radiation therapy was associated with high pharmacokinetic exposure. No evidence of exposure-driven grade ≥2 or ≥3 peripheral neuropathy or grade ≥3 neutropenia was seen in exposure-safety and BW-based subgroup analyses; the incidence of these safety events was comparable across pediatric age subgroups, despite lower exposure in younger children. CONCLUSIONS: No further adjustments based on age or BW are required for the BV dose (1.8 mg/kg Q3W) approved in children.

Global, regional, and national burden of stroke attributable to extreme low temperatures, 1990-2019: A global analysis.

BACKGROUND: Extreme ambient temperatures have been linked to increased risks of stroke morbidity and mortality. However, global estimates of the burden of stroke due to extreme low temperatures are not well-defined. AIMS: This study aimed to determine the global burden of stroke due to extreme low temperatures and its spatiotemporal trend from 1990 to 2019. METHODS: Based on the Global Burden of Disease Study 2019, we obtained global, regional, and national data on deaths, disability-adjusted life years (DALYs), age-standardized mortality rate (ASMR), and age-standardized rate of DALYs (ASDR) of stroke attributed to extreme low temperatures, further stratified by age, sex, and sociodemographic index (SDI). RESULTS: Globally, in 2019, an estimated 474,000 stroke deaths with the corresponding ASMR (6.2 (95% uncertainty interval (UI): 4.6-7.9)) and ASDR (103.9 (95% UI: 77.0-134.5)) per 100,000 population, were attributable to extreme low temperatures. The most significant burden was observed in Central Asia, followed by Eastern Europe and East Asia. From 1990 to 2019, the global burden of stroke and its subtypes (ischemic stroke, intracerebral hemorrhage, and subarachnoid hemorrhage) attributable to extreme low temperatures exhibited a decrease in both ASMR and ASDR. Significant decreases in stroke burden occurred in the high-SDI regions, high-income Asia Pacific, and subarachnoid hemorrhage cases. Moreover, the ASMR and ASDR increased with age and were higher in males than females. CONCLUSION: The global stroke burden due to extreme low temperatures remains high despite a decreasing trend over the past three decades. The stroke burden due to extreme low temperatures was more notable for Central Asia, older people, and the male sex.

Clinical Study on the Management of Aortic Dissection Involving the Aortic Arch through Endovascular Isolation and In Situ Fenestration with Covered Stent.

Objective: This study aimed to investigate the clinical effectiveness of the SilverFlow branch stent through endovascular isolation and in situ fenestration (ISF) for the treatment of aortic dissection (AD) involving the aortic arch. Methods: A total of 21 patients with AD involving the aortic arch, admitted to our hospital between September 2021 and January 2023, were selected for this prospective study. All patients underwent treatment with an endoluminal isolated ISF-covered stent, with the branch stent being the SilverFlow, developed by Shenzhen Xianjian Company. We assessed the success rate of the ISF procedure stent-related complications and compared the volumes of the true and false cavities before and after treatment. Follow-up evaluations were conducted 1, 3, and 6 months post-operation, focusing on neurological complications, mortality, and the need for secondary interventional treatment. Results: Among the 21 AD patients with aortic arch involvement, 20 (95.23%) underwent non-emergency surgery, while 1 (4.76%) required emergency surgery due to cardiac ischemia and signs of dissection rupture. All surgeries were successfully completed. After treatment, the average volume of the true lumen significantly decreased compared to pre-treatment levels, while the volume of the false lumen significantly increased (P < .05). The success rate was 100%, with only one case (4.76%) experiencing type I internal leakage. There were no cases of stent displacement, distortion, or fenestration vessel occlusion. One patient (4.76%) succumbed to acute pericardial tamponade, resulting in a mortality rate of 4.76%. Another patient (4.76%) suffered from upper limb ischemia, significantly improving with antithrombotic drug treatment. No occurrences of stroke, visceral ischemia, or other complications were reported, and no secondary interventional treatments were required. Conclusions: The application of the SilverFlow branch stent for endovascular isolation of ISF in AD cases involving the aortic arch demonstrates a high success rate, low complication and mortality rates, and significant clinical feasibility and value.

Effect and interaction of TNKS genetic polymorphisms and environmental factors on telomere damage in COEs-exposure workers.

Coke oven emissions (COEs) contain many carcinogenic polycyclic aromatic hydrocarbons (PAHs). Telomere damage is an early biological marker reflecting long-term COEs-exposure. Whereas, whether the genetic variations of telomere-regulated gene TNKS have an effect on the COEs-induced telomere damage is unknown. So we detected the environmental exposure levels, relative telomere length (RTL), and TNKS genetic polymorphisms among 544 COEs-exposure workers and 238 healthy participants. We found that the RTL of the wild homozygous GG genotype in rs1055328 locus was statistically shorter compared with the CG+CC genotype for the healthy participants using covariance analysis(P = 0.008). In the Generalized linear model (GLM) analysis, TNKS rs1055328 GG could accelerate telomere shortening (P = 0.011); and the interaction between TNKS rs1055328 GG and COEs-exposure had an effect on RTL (P = 0.002). In conclusion, this study was the first to discover the role of TNKS rs1055328 locus in COEs-induced telomere damage, and proved that chromosomal damage was a combined consequence of environmental and genetic factors.

Influence of the methyl group in isoprene epoxides on reactivity compared to butadiene epoxides: Biological significance.

Reactions of the epoxides of 1,3-butadiene and isoprene (2-methyl-1,3-butadiene) with oxygen, nitrogen and sulfur nucleophiles have been compared to enable a better molecular understanding of the relative human toxicities of these epoxides. Hydrolysis of rac.-ethenyloxirane in (18O)water gave 77% (2-18O)but-3-ene-1,2-diol and 23% (1-18O)but-3-ene-1,2-diol. The R:S ratio for but-3-ene-1,2-diol from hydrolysis of (S)-ethenyloxirane was 75:25. Hence, hydrolysis of ethenyloxirane occurs by competing SN2 attack at C-2 and C-3 in 3:1 ratio, with no SN1 component. Hydrolysis of rac.-2-ethenyl-2-methyloxirane gave 2-hydroxy-2-methylbut-3-en-1-ol (73%) and 27% of a 2:1 mixture of the E- and Z-isomers of 4-hydroxy-2-methylbut-2-en-1-ol. In (18O)water (2-18O)2-hydroxy-2-methylbut-3-en-1-ol was obtained. Formation of these products occurs via SN1 ionisation to resonance-stabilised allylic cations which are captured by water. Reaction of rac.-ethenyloxirane with l-valine methyl ester gave diastereoisomeric adducts from SN2 attack of the valine amino at both C-2 (substituted position) and C-3 of the oxirane. The corresponding reaction of rac.-2-methyl-2-ethenyloxirane gave diastereoisomeric adducts, (R, S)- and (S, S)-N-(2-hydroxy-2-methyl-3-buten-1-yl)-l-valine methyl ester, from SN2 attack of the valine amino solely at C-3. Reactions of rac.-2-ethenyl-2-methyloxirane with cysteine derivatives occurred at C-2 in neutral polar media (SN1 reaction) or at C-3 in basic media (SN2), whereas for ethenyloxirane products arose from attack at both C-2 and C-3. Reaction of meso-butadiene diepoxide (meso-2,2'-bioxirane) with l-valine methyl ester gave mainly 2:1 adducts, dimethyl 2,2'-(((2R,3S)-2,3-dihydroxybutane-1,4-diyl)bis(azanediyl))-(2S,2'S)-bis(3-methyl-butanoates), whereas 2-methyl-2,2'-bioxirane gave a mixture of 1:1 [methyl 2-(3,4-dihydroxy-3-methylpyrrolidin-1-yl)-3-methylbutanoates] and 2:1 adducts. Meso-2,2'-bioxirane reacted with N-acetylcysteine methyl ester in methanol to afford meso-thiolane-3,4-diol, by elimination of N-acetyldehydroalanine methyl ester from a precursor cyclic adduct. Similarly, 2-methyl-2,2'-bioxirane gave solely 3-methylthiolane-3,4-diols. Thus, the methyl group of isoprene has a subtle effect on the reactivity of its epoxides relative to those of butadiene and therefore, in the context of their toxicology, could abrogate crosslinking of nitrogen functions in biomolecules related to mutagenicity and carcinogenicity.

Circular RNAs in stem cells: from basic research to clinical implications.

Circular RNAs (circRNAs) are a special class of endogenous RNAs with a wide variety of pathophysiological functions via diverse mechanisms, including transcription, microRNA (miRNA) sponge, protein sponge/decoy, and translation. Stem cells are pluripotent cells with unique properties of self-renewal and differentiation. Dysregulated circRNAs identified in various stem cell types can affect stem cell self-renewal and differentiation potential by manipulating stemness. However, the emerging roles of circRNAs in stem cells remain largely unknown. This review summarizes the major functions and mechanisms of action of circRNAs in stem cell biology and disease progression. We also highlight circRNA-mediated common pathways in diverse stem cell types and discuss their diagnostic significance with respect to stem cell-based therapy.

Repurposing Artemisinin and its Derivatives as Anticancer Drugs: A Chance or Challenge?

Cancer has become a global health problem, accounting for one out of six deaths. Despite the recent advances in cancer therapy, there is still an ever-growing need for readily accessible new therapies. The process of drug discovery and development is arduous and takes many years, and while it is ongoing, the time for the current lead compounds to reach clinical trial phase is very long. Drug repurposing has recently gained significant attention as it expedites the process of discovering new entities for anticancer therapy. One such potential candidate is the antimalarial drug, artemisinin that has shown anticancer activities in vitro and in vivo. In this review, major molecular and cellular mechanisms underlying the anticancer effect of artemisinin and its derivatives are summarised. Furthermore, major mechanisms of action and some key signaling pathways of this group of compounds have been reviewed to explore potential targets that contribute to the proliferation and metastasis of tumor cells. Despite its established profile in malaria treatment, pharmacokinetic properties, anticancer potency, and current formulations that hinder the clinical translation of artemisinin as an anticancer agent, have been discussed. Finally, potential solutions or new strategies are identified to overcome the bottlenecks in repurposing artemisinin-type compounds as anticancer drugs.

MicroRNA-1 facilitates hypoxia-induced injury by targeting NOTCH3.

Cell proliferation, apoptosis, and autophagy have been reported to be related to myocardial ischemia injury. MicroRNAs have attracted wide attention on regulating cell proliferation, apoptosis, and autophagy. miR-1 expression has been reported to be dysregulated in cardiac tissue or cells with hypoxia, while the exact roles as well as underlying mechanism remain poorly understood. In this study, we investigated the potential roles of miR-1 in cell proliferation, apoptosis, and autophagy in hypoxia-treated cardiac injury and explored the underlying mechanism using H9c2 cells. Results showed that hypoxic stimulation inhibited cell proliferation and the expression of miR-1 but promoted cell apoptosis in H9c2 cells. Moreover, overexpression of miR-1 promoted cell apoptosis and inhibited cell proliferation and autophagy in H9c2 cells treated with hypoxia, while its knockdown played an opposite effect. In addition, bioinformatics, luciferase reporter, and RNA immunoprecipitation analyses indicated that NOTCH3 was a direct target of miR-1 and its upregulation reversed the effects of miR-1 on cell proliferation, apoptosis, and autophagy in hypoxia-treated H9c2 cells. Taken together, our data suggested that miR-1 promoted hypoxia-induced injury by targeting NOTCH3, indicating novel therapeutic targets for treatment of myocardial ischemia injury.

Effects of polycyclic aromatic hydrocarbon exposure and miRNA variations on peripheral blood leukocyte DNA telomere length: A cross-sectional study in Henan Province, China.

Telomeres play a major role in human aging and disease, especially in most cancers. Telomere length was shortened in workers exposed to polycyclic aromatic hydrocarbons (PAHs) and influenced by individual genetic variations in telomere-binding proteins. MicroRNAs (miRNAs) can affect the progress of messenger RNA (mRNA) transcription; however, whether polymorphisms in miRNA can act on the telomere length is still unknown. Therefore, we aimed to explore the relationships between telomere damage and genetic polymorphisms in miRNA or environmental exposure. A total of 544 coke oven workers and 238 healthy controls were recruited. After collecting peripheral blood and extracting the genomic DNA of the study subjects, the telomere length (TL) in their leucocytes was detected by a real-time quantitative polymerase chain reaction (PCR), and polymorphisms in miRNAs were genotyped using the flight mass spectrometry technique. The concentrations of the four urine OH-PAHs were determined by high performance liquid chromatography (HPLC), and the Soxhlet extraction method was used to detect the concentration of coke oven emissions (COEs) in the air. We found that the peripheral blood leucocyte DNA TL was significantly shorter in the exposure group (0.75; 0.51, 1.08) than that in the control group (1.05; 0.76, 1.44) (Z = 7.692, P < 0.001). The total cumulative exposure dose (CED), 1-hydroxypyrene, 2-hydroxynaphthalene, and 3-hydroxyphenanthrene were significantly negatively correlated with TL (r = -0.307, P < 0.001; r = -0.212, P < 0.001; r = -0.110, P = 0.025; r = -0.251, P < 0.001, respectively). MiR-145 rs353291 GG, miR-30a rs2222722 CT/CC, and miR-197 rs1889470 AA could protect the telomere end in the exposed workers (P < 0.05). The interaction between miR-197 rs1889470 and the CED had an effect on TL (ß = 0.066, P = 0.034). This is the first study to evaluate gene-environmental interactions for miRNA polymorphisms and PAH exposure in coke oven workers.

Genetic polymorphisms, mRNA expression levels of telomere-binding proteins, and associates with telomere damage in PAHs-Exposure workers.

Coke oven emissions (COEs), confirmed human carcinogens, are mainly composed of polycyclic aromatic hydrocarbons (PAHs). Telomere shortening in blood leukocytes has been associated with COEs, and polymorphisms in metabolic enzymes. However, the relationship between polymorphisms in telomere related genes and telomere shortening in COEs exposed workers has never been evaluated. Therefore, we measured telomere length and mRNA expression levels of telomere-binding proteins (TBPs) by qPCR method in leucocyte from 544 COEs exposed workers and 238 office staffs (referents). Flight mass spectrometry was used to perform the genotyping of selected functional and susceptible SNPs. The results showed that the telomere length in the exposure group 0.75(0.51,1.08) was significantly shorter than that in the control group 1.05(0.76,1.44) (P < 0.001). The mRNA expression levels of TPP1, TERF1 and TERF2 genes in the exposure group were significantly lower than those in the control group (P < 0.05), the mRNA expression level of POT1 in the exposure group was significantly higher than that in the control group (P < 0.05). We used the wild homozygous genotype as a reference, subjects carrying TERT rs2736109 AA, TERT rs3215401 CC and TERT rs2736100 GT + GG genotypes had significantly longer telomere length in the exposure group (P < 0.05). In conclusion, the workers exposed to COEs had shorter telomere length, which was regulated by the TPP1, TERF1, TERF2 and POT1 genes expression levels, and the gene polymorphisms of TERT gene were associated with the telomere length among PAHs-exposure workers.

Pharmacokinetic Properties of Humanized IgG1 and IgG4 Antibodies in Preclinical Species: Translational Evaluation.

Assessment of the factors that regulate antibody exposure-response relationships in the relevant animal models is critical for the design of successful translational strategies from discovery to the clinic. Depending on the specific clinical indication, preclinical development paradigms may require that the efficacy or dosing-related attributes for the existing antibody be assessed in various species when cross-reactivity of the lead antibody to the intended species is justified. Additionally, with the success of monoclonal antibodies for management of various human conditions, a parallel interest in therapeutic use of these novel modalities in various veterinary species has followed. The protective role of neonatal Fc receptor (FcRn) in regulation of IgG homeostasis and clearance is now well recognized and the "nonspecific clearance" of antibodies through bone marrow-derived phagocytic and vascular endothelial cells (via lysosomal processes) is modulated by interactions with FcRn receptors. In this study, we have attempted to examine the PK properties of human IgG antibodies in dog and monkey. These studies establish a translational framework for evaluation of IgG antibody PK properties across species.

Integrative Pharmacology: Advancing Development of Effective Immunotherapies.

With the recent advances in cancer immunotherapy, it is now evident that the antigen-specific activation of the patients' immune responses can be utilized for achieving significant therapeutic benefits. Novel molecules have been developed and promising advances have been achieved in cancer therapy. The recent success of cancer immunotherapy clearly reflects the novelty of the approach and importance of this class of therapeutics. Due to the nature of immunotherapy, i.e., harnessing the patient's immune system, it becomes critical to evaluate the important variables that can guide preclinical development, translational strategies, patient selection, and effective clinical dosing paradigms following single and combination therapies. To further boost the durability and efficacy profiles of IO (immuno-oncology) drugs following single agent therapy, novel combination therapies are being sought. Combination strategies have become critical for enhancing the anti-tumor immunity in broader cancer indications. Comprehensive methods are being developed to quantify the synergistic combination effect profiles at various development phases. Further evaluation of the signaling and pathway components can potentially establish a unique "signature" characteristic for specific combination therapies following modulation of various immunomodulatory pathways. In this article, critical topics related to preclinical, translational, and clinical development of IO agents are discussed.

H19 knockdown suppresses proliferation and induces apoptosis by regulating miR-148b/WNT/ß-catenin in ox-LDL -stimulated vascular smooth muscle cells.

BACKGROUND: Long non-coding RNAs (lncRNAs) have been identified as critical regulators in the development of atherosclerosis (AS). Here, we focused on discussing roles and molecular mechanisms of lncRNA H19 in vascular smooth muscle cells (VSMCs) progression. METHODS: RT-qPCR assay was used to detect the expression patterns of H19 and miR-148b in clinical samples and cells. Cell proliferative ability was evaluated by CCK-8 and colony formation assays. Cell apoptotic capacity was assessed by apoptotic cell percentage and the caspase-3 activity. Bioinformatics analysis, luciferase and RNA immunoprecipitation (RIP) assays were employed to demonstrate cell percentage and the relationship among H19, miR-148b and wnt family member 1 (WNT1). Western blot assay was performed to determine expressions of proliferating cell nuclear antigen (PCNA), ki-67, Bax, Bcl-2, WNT1, ß-catenin, C-myc and E-cadherin. RESULTS: The level of H19 was increased and miR-148b expression was decreased in human AS patient serums and oxidized low-density lipoprotein (ox-LDL)-stimulated human aorta vascular smooth muscle cells (HA-VSMCs). H19 knockdown suppressed proliferation and promoted apoptosis in HA-VSMCs following the treatment of ox-LDL. H19 inhibited miR-148b expression by direct interaction. Moreover, miR-148b inhibitor could reverse the effects of H19 depletion on proliferation and apoptosis in ox-LDL-stimulated HA-VSMCs. Further mechanical explorations showed that WNT1 was a target of miR-148b and H19 acted as a competing endogenous RNA (ceRNA) of miR-148b to enhance WNT1 expression. Furthermore, miR-148 inhibitor exerted its pro-proliferation and anti-apoptosis effects through activating WNT/ß-catenin signaling in ox-LDL-stimulated HA-VSMCs. CONCLUSION: H19 facilitated proliferation and inhibited apoptosis through modulating WNT/ß-catenin signaling pathway via miR-148b in ox-LDL-stimulated HA-VSMCs, implicating the potential values of H19 in AS therapy.

TUG1 knockdown ameliorates atherosclerosis via up-regulating the expression of miR-133a target gene FGF1.

BACKGROUND: Long non-coding RNAs (lncRNAs) have been revealed to participate in the pathological events associated with atherosclerosis. However, the exact role of lncRNA taurine-up-regulated gene 1 (TUG1) and its possible molecular mechanism in atherosclerosis remain unidentified. METHODS: High-fat diet (HFD)-treated ApoE-/- mice were used as an in vivo model of atherosclerosis. Ox-LDL-induced macrophages and vascular smooth muscle cells (VSMCs) were employed as cell models of atherosclerosis. qRT-PCR was performed to detect the expression of TUG1 and miR-133a. Serum levels of total cholesterol (TC), triglyceride (TG), low-density lipoprotein cholesterol (LDL-C), and high-density lipoprotein cholesterol (HDL-C) were analyzed by commercially available enzyme kits. Oil red O and hematoxylin and eosin (H&E) staining were conducted to examine atherosclerotic lesion. Luciferase reporter assay combined with RNA immunoprecipitation (RIP) was applied to confirm the interaction between TUG1, miR-133a and FGF1. Cell proliferation ability was determined by Cell Counting Kit-8 (CCK-8) assay and trypan blue dye exclusion test. Cell apoptosis was evaluated with TUNEL assay. Expression and production of inflammatory cytokines was measured with western blot and ELISA analysis. RESULTS: TUG1 expression was up-regulated in HFD-treated ApoE-/- mice, as well as in ox-LDL-induced RAW264.7 and MOVAS cells. TUG1 knockdown inhibited hyperlipidemia, decreased inflammatory response, and attenuated atherosclerotic lesion in HFD-treated ApoE-/- mice. TUG1 could function as a molecular sponge of miR-133a to suppress its expression. TUG1 overexpression accelerated cell growth, improved inflammatory factor expression, and inhibited apoptosis in ox-LDL-stimulated RAW264.7 and MOVAS cells, while this effect was abated after transfection with miR-133 mimic. Moreover, fibroblast growth factor 1 (FGF1) was identified as a direct target of miR-133a. Restored expression of FGF1 overturned the effect of miR-133a on cell proliferation, inflammatory factor secretion and apoptosis in ox-LDL-treated RAW264.7 and MOVAS cells. Finally, TUG1 was revealed to up-regulate FGF1 expression by sponging miR-133a. CONCLUSION: TUG1 knockdown ameliorates atherosclerosis by modulating FGF1 via miR-133a, raising the possibility of targeting TUG1 as an atheroprotective therapeutic strategy.

Clinical Pharmacokinetics of Mycophenolic Acid in Hematopoietic Stem Cell Transplantation Recipients.

Mycophenolate mofetil (MMF), an ester prodrug of mycophenolic acid (MPA), is widely used as a maintenance immunosuppressive regimen in solid organ transplant patients. It is increasingly used for the prophylaxis and treatment of graft-versus-host disease (GVHD) in hematopoietic stem cell transplantation (HSCT) patients. MPA displays extensive binding to serum albumin and glucuronidation to the inactive MPA-7-O-glucuronide (MPAG). Here, we review and discuss the pertinent information regarding the clinical pharmacokinetics of MPA in HSCT patients. The pharmacokinetics of MPA are altered in HSCT patients with lower oral bioavailability, shorter half-life and higher clearance than those in healthy volunteers and renal transplant recipients. Moreover, clearance may be increased in young pediatric patients. The optimal MMF dosing and preferred targets are still under investigation in HSCT patients due to the substantial intra- and inter-individual pharmacokinetic variability of MPA and broad range of transplants (malignant vs. nonmalignant, related vs. unrelated donor, and human leukocyte antigen mismatch). The complex pharmacokinetics of MPA have partly hampered the efficient use of MMF, and pharmacokinetic studies in HSCT patients have been limited in size and mostly inconclusive. Future research should be multi-institutional and focus on developing clinical decisions with adequate statistical power to improve clinical care of HSCT recipients.

Pharmacokinetic Variability of Mycophenolic Acid in Pediatric and Adult Patients With Hematopoietic Stem Cell Transplantation.

The aim of this study was to evaluate the pharmacokinetic variations of mycophenolic acid (MPA), the active metabolite of mycophenolate mofetil (MMF), in both pediatric and adult patients following hematopoietic stem cell transplantation (HSCT). Twenty pediatric patients with a median age of 3 years (range 0.2-12 years) and 13 adult patients with a median age of 54 years (range 18-63 years) were enrolled. Blood samples were collected on days 0, 7, 14, 21, and 30 after allogeneic HSCT. Total and free (unbound) MPA as well as MPA 7-O-glucuronide (MPAG) were quantified using a validated LC-MS/MS assay. The plasma protein binding of MPA and MPAG did not change significantly in pediatric patients over the 1-month sampling period post-HSCT. However, it increased in adult patients from day 7 to day 30 post-HSCT, from 97.3 ± 0.8% to 98.3 ± 0.6% for MPA (P < .05), and 74.6 ± 9.4% to 82.9 ± 8.1% for MPAG (P < .05). The plasma protein binding of MPA was significantly higher in males compared to females in both pediatric (98.3 ± 1.1% vs 97.4 ± 1.1%) and adult (98.1 ± 0.7% vs 97.4 ± 1.2%) patients (P < .05). The MPAG/MPA ratios on a milligram-per-kilogram dose basis in adult patients were significantly higher than those in pediatric patients (4.3 ± 3.4 vs 2.4 ± 2.6; P < .05). Time-dependent plasma protein binding and age-related differences in MPA metabolism at least in part impact the reported large intra- and interindividual variability in MPA pharmacokinetics. These patient and pharmacologic factors, if incorporated into MMF regimen design and modification, may contribute to the rational dose selection of MMF in HSCT patients.

Simultaneous quantification of mycophenolic acid and its glucuronide metabolites in human plasma by an UPLC-MS/MS assay.

The aim of this study was to develop a reliable UPLC-MS/MS assay for accurate quantification of mycophenolic acid (MPA) and its glucuronide conjugates in human plasma. Plasma proteins were precipitated with acetonitrile and the chromatographic separation was achieved on a C18 column with a gradient elution. The detection was performed by a triple quadrupole mass spectrometer in the positive electrospray ionization and multiple reaction monitoring mode. Linearity of the assay was demonstrated over the range of 20-10,000 ng/mL for MPA and MPA glucuronide (MPAG), and 2-1000 ng/mL for acyl MPA glucuronide in human plasma. The assay was precise and accurate with coefficient of variation and bias <15%. MPA and MPAG were stable at 25 °C up to 1 day in both heparin- and EDTA-treated blood. In heparin- and EDTA-plasma, MPA and MPAG were stable for at least 1 week at 25 and 4 °C, and 1 month at -20 °C. However, 99% acyl MPA glucuronide degraded in both heparin- and EDTA-blood as well as plasma when stored at room temperature for 1 day. All the analytes remained stable for at least 3 months in acidified EDTA-plasma at -80 °C. The assay was successfully applied on patients post hematopoietic stem cell transplantation. Copyright © 2016 John Wiley & Sons, Ltd.

Quantitative determination of dopamine in human plasma by a highly sensitive LC-MS/MS assay: Application in preterm neonates.

The determination of dopamine facilitates better understanding of the complex brain disorders in the central nervous system and the regulation of endocrine system, cardiovascular functions and renal functions in the periphery. The purpose of this study was to develop a highly sensitive and reliable assay for the quantification of dopamine in human neonate plasma. Dopamine was extracted from human plasma by strong cation exchange (SCX) solid phase extraction (SPE), and subsequently derivatized with propionic anhydride. The derivatized analyte was separated by a Waters Acquity UPLC BEH C18 column using gradient elution at 0.4 ml/min with mobile phases A (0.2% formic acid in water [v/v]) and B (MeOH-ACN [v/v, 30:70]). Analysis was performed under positive electrospray ionization tandem mass spectrometer (ESI-MS/MS) in the multiple reaction monitoring (MRM) mode. The stable and relatively non-polar nature of the derivatized analyte enables reliable quantification of dopamine in the range of 10-1000 pg/ml using 200 µl of plasma sample. The method was validated with intra-day and inter-day precision less than 7%, and the intra-day and inter-day accuracy of 91.9-101.9% and 92.3-102.6%, respectively. The validated assay was applied to quantify dopamine levels in two preterm neonate plasma samples. In conclusion, a sensitive and selective LC-MS/MS method has been developed and validated, and successfully used for the determination of plasma dopamine levels in preterm neonates.

Development and validation of a highly sensitive LC-MS/MS assay for the quantification of arginine vasopressin in human plasma and urine: Application in preterm neonates and child.

Arginine vasopressin is an endogenous neuropeptide secreted in response to situations such as hyperosmolality, hypotension and hypovolemia. The purpose of this study was to develop a reliable assay using small volumes of plasma and urine samples to quantify vasopressin levels in preterm infants. Weak cation solid-phase extraction was used to extract vasopressin from 200µl human plasma and urine samples. Separation was achieved on a Waters Acquity UPLC BEH C18 column by gradient elution at 0.55ml/min, with a mobile phase composed of methanol and 0.02% aqueous acetic acid solution. Analysis was performed under a hybrid triple quadrupole linear ion trap mass spectrometer, operated in multiple reaction monitoring mode using positive ionization. The linear response range was 1.0-40pg/ml for vasopressin, with the lower limit of quantification (LLOQ) of 1.0pg/ml in human plasma and urine. Recoveries at concentrations of 3, 10 and 32pg/ml were all greater than 70%, and matrix effects were within 15%. The method was validated with intra-day and inter-day precision of less than 8% for human plasma and urine. The intra-day and inter-day accuracy for human plasma were 91.9-100.6% and 92.3-104.8%, respectively. The intra-day and inter-day accuracy for human urine were 89.2-95.9% and 89.3-91.3%, respectively. The validated method was successfully applied to analyze two preterm neonate plasma samples and one child urine sample. In conclusion, the developed and validated method was sensitive and reliable, and was successfully used to quantify endogenous vasopressin levels in neonate plasma and child urine.