334 results on '"K, Venkatakrishnan"'
Search Results
2. Mathematical modeling of an experiment for the growth of chia seeds sprouts (Salvia hispanica L.)
- Author
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K. Venkatakrishnan, J. Jing, A.Yu. Chechetkina, M.B. Muradova, and L.A. Nadtochii
- Subjects
food ,Salvia hispanica ,Botany ,General Medicine ,Biology ,food.food - Abstract
World Health Organization (WHO) has reported that more than 80% of the population in developing countries uses herbal medicine. Modern technologies open up the possibility of controlling the cultivation of medicinal plants for commercial use. The combination of various methods of controlled cultivation is a high-tech and capital-intensive direction for the development of the agricultural industry in Russia. This article considers the selection of optimal conditions for growing of chia seeds sprouts as a multifactor experiment with three incoming factors at two levels. For this study 100 grains of dark varieties of chia seeds (Salvia hispanica L.) purchased from Era Green were used. The 3 major incoming factors include moisture (3, 4 and 5 ml of added water), the temperature (20, 25 and 30 °C), and the light (expose duration for 0, 12 and 24 h) under LED lamps with peaks at 440-450 nm (blue spectrum) and 660 nm (red spectrum). Using different factors, we found that the speed of germination and the seedling vigor were considerably improved. This multifactor model helps to establish more reliable information on the rational ways for obtaining chia seeds sprouts in the conditions of controlled cultivation with high yield.
- Published
- 2020
3. Optimizing Oncology Therapeutics Through Quantitative Translational and Clinical Pharmacology: Challenges and Opportunities
- Author
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K Venkatakrishnan, LE Friberg, D Ouellet, JT Mettetal, A Stein, IF Trocóniz, R Bruno, N Mehrotra, J Gobburu, and DR Mould
- Subjects
Oncology ,medicine.medical_specialty ,Biomedical Research ,Drug Evaluation, Preclinical ,Antineoplastic Agents ,law.invention ,Translational Research, Biomedical ,law ,Neoplasms ,Internal medicine ,medicine ,Animals ,Humans ,Computer Simulation ,Pharmacology (medical) ,Molecular Targeted Therapy ,Pharmacology ,Clinical pharmacology ,business.industry ,Models, Theoretical ,Clinical method ,Review article ,Drug Design ,Pharmacology, Clinical ,Oncology drug ,business ,Clinical evaluation ,Dose selection - Abstract
Despite advances in biomedical research that have deepened our understanding of cancer hallmarks, resulting in the discovery and development of targeted therapies, the success rates of oncology drug development remain low. Opportunities remain for objective dose selection informed by exposure-response understanding to optimize the benefit-risk balance of novel therapies for cancer patients. This review article discusses the principles and applications of modeling and simulation approaches across the lifecycle of development of oncology therapeutics. Illustrative examples are used to convey the value gained from integration of quantitative clinical pharmacology strategies from the preclinical-translational phase through confirmatory clinical evaluation of efficacy and safety.
- Published
- 2014
4. An Acousto-Optic Vibrometer for Measurement of Vibration in Ultra-Precision Machine Tools
- Author
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Bryan Kok Ann Ngoi and K. Venkatakrishnan
- Subjects
Accuracy and precision ,Engineering ,business.product_category ,Precision engineering ,business.industry ,Mechanical Engineering ,Industrial and Manufacturing Engineering ,Computer Science Applications ,Machine tool ,Vibration ,Surface micromachining ,Machining ,Control and Systems Engineering ,Electronic engineering ,Laser scanning vibrometry ,business ,Laser Doppler vibrometer ,Software - Abstract
Measurement of vibration is a vital factor that limits the precision and accuracy of machining of micro and macro components. In this paper, a novel technique for measurement of vibration is proposed using an acousto-optic modulator, which highlights an improved approach in measuring vibration in the subnanometre range. An experimental comparison was made with a laser Doppler vibrometer. This novel concept is proposed for application to a precision machine tool to measure the vibration on the machine bed induced during the machining process and by the external environment, which can be compensated for by in-process techniques. This novel measurement technique can also be applied for the precision measurement of the stage movement in ultra-precision machines to a subnanometre resolution.
- Published
- 2000
5. Biocatalyst-mediated expansion of ring D in azadirachtin, a potent insect antifeedant from Azadirachta indica
- Author
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K Venkatakrishnan and K.M Madyastha
- Subjects
biology ,Microorganism ,media_common.quotation_subject ,Organic Chemistry ,Nocardia ,Insect ,Azadirachta ,Ring (chemistry) ,biology.organism_classification ,Biochemistry ,chemistry.chemical_compound ,Azadirachtin ,chemistry ,Biocatalysis ,Drug Discovery ,Organic chemistry ,media_common - Abstract
A microorganism identified as Nocardia Sp.capable of converting azadirachtin 1 into three metabolites, viz. 3-deacetylazadirachtin 2, 1-detigloyl-3-deacetyl-azadirachtin-1-ene-3-one 3 and 1-detigloyl-3-deacetyl-11,19-deoxa-12,19-oxa-11-oxo-azadirachtin-1-ene-3-one 4, has been isolated. This is the first report on the functionalization of azadirachtin using biocatalysts wherein two novel, hitherto unknown metabolites have been isolated and characterized.
- Published
- 1999
6. ChemInform Abstract: Biocatalyst-Mediated Efficient Functionalization of Ring A in Salannin, a Tetranortriterpene from Azadirachta indica
- Author
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K. Venkatakrishnan and K. M. Madyastha
- Subjects
Terpene ,biology ,Biocatalysis ,Chemistry ,Organic chemistry ,Surface modification ,General Medicine ,Azadirachta ,Ring (chemistry) ,biology.organism_classification - Published
- 2010
7. Application of the relative activity factor approach in scaling from heterologously expressed cytochromes p450 to human liver microsomes: studies on amitriptyline as a model substrate
- Author
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K, Venkatakrishnan, L L, von Moltke, and D J, Greenblatt
- Subjects
Isoenzymes ,Ketoconazole ,Phenotype ,Cytochrome P-450 Enzyme System ,Amitriptyline ,Microsomes, Liver ,Humans ,Biotransformation ,Recombinant Proteins - Abstract
The relative activity factor (RAF) approach is being increasingly used in the quantitative phenotyping of multienzyme drug biotransformations. Using lymphoblast-expressed cytochromes P450 (CYPs) and the tricyclic antidepressant amitriptyline as a model substrate, we have tested the hypothesis that the human liver microsomal rates of a biotransformation mediated by multiple CYP isoforms can be mathematically reconstructed from the rates of the biotransformation catalyzed by individual recombinant CYPs using the RAF approach, and that the RAF approach can be used for the in vitro-in vivo scaling of pharmacokinetic clearance from in vitro intrinsic clearance measurements in heterologous expression systems. In addition, we have compared the results of two widely used methods of quantitative reaction phenotyping, namely, chemical inhibition studies and the prediction of relative contributions of individual CYP isoforms using the RAF approach. For the pathways of N-demethylation (mediated by CYPs 1A2, 2B6, 2C8, 2C9, 2C19, 2D6, and 3A4) and E-10 hydroxylation (mediated by CYPs 2B6, 2D6, and 3A4), the model-predicted biotransformation rates in microsomes from a panel of 12 human livers determined from enzyme kinetic parameters of the recombinant CYPs were similar to, and correlated with the observed rates. The model-predicted clearance via N-demethylation was 53% lower than the previously reported in vivo pharmacokinetic estimates. Model-predicted relative contributions of individual CYP isoforms to the net biotransformation rate were similar to, and correlated with the fractional decrement in human liver microsomal reaction rates by chemical inhibitors of the respective CYPs, provided the chemical inhibitors used were specific to their target CYP isoforms.
- Published
- 2001
8. CYP3A4 is the major CYP isoform mediating the in vitro hydroxylation and demethylation of flunitrazepam
- Author
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L M, Hesse, K, Venkatakrishnan, L L, von Moltke, R I, Shader, and D J, Greenblatt
- Subjects
Benzoflavones ,Ritonavir ,Flunitrazepam ,Hydroxylation ,Transfection ,Methylation ,Quinidine ,Mixed Function Oxygenases ,Isoenzymes ,Kinetics ,Ketoconazole ,Anti-Anxiety Agents ,Cytochrome P-450 Enzyme System ,Sulfaphenazole ,Microsomes, Liver ,Cytochrome P-450 CYP3A ,Cytochrome P-450 Enzyme Inhibitors ,Humans ,Enzyme Inhibitors ,Omeprazole - Abstract
The kinetics of flunitrazepam (FNTZ) N-demethylation to desmethylflunitrazepam (DM FNTZ), and 3-hydroxylation to 3-hydroxyflunitrazepam (3-OH FNTZ), were studied in human liver microsomes and in microsomes containing heterologously expressed individual human CYPs. FNTZ was N-demethylated by cDNA-expressed CYP2A6 (K(m) = 1921 microM), CYP2B6 (K(m) = 101 microM), CYP2C9 (K(m) = 50 microM), CYP2C19 (K(m) = 60 microM), and CYP3A4 (K(m) = 155 microM), and 3-hydroxylated by cDNA-expressed CYP2A6 (K(m) = 298 microM) and CYP3A4 (K(m) = 286 microM). The 3-hydroxylation pathway was predominant in liver microsomes, accounting for more than 80% of intrinsic clearance compared with the N-demethylation pathway. After adjusting for estimated relative abundance, CYP3A accounted for the majority of intrinsic clearance via both pathways. This finding was supported by chemical inhibition studies in human liver microsomes. Formation of 3-OH FNTZ was reduced to 10% or less of control values by ketoconazole (IC(50) = 0.11 microM) and ritonavir (IC(50) = 0.041 microM). Formation of DM FNTZ was inhibited to 40% of control velocity by 2.5 microM ketoconazole and to 30% of control by 2.5 microM ritonavir. Neither 3-OH FNTZ nor DM FNTZ formation was inhibited to less than 85% of control activity by alpha-naphthoflavone (CYP1A2), sulfaphenazole (CYP2C9), omeprazole (CYP2C19), or quinidine (CYP2D6). Thus, CYP-dependent FNTZ biotransformation, like that of many benzodiazepine derivatives, is mediated mainly by CYP3A. Clinical interactions of FNTZ with CYP3A inhibitors can be anticipated.
- Published
- 2001
9. 661 A pharmacokinetic, pharmacodynamic and electrocardiographic study of L-MTP-PE in healthy volunteers
- Author
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Cristina Oliva, W.G. Kramer, D.B. Goodman, K. Venkatakrishnan, and Timothy W. Synold
- Subjects
Cancer Research ,Oncology ,business.industry ,Pharmacokinetic pharmacodynamic ,Healthy volunteers ,Medicine ,Pharmacology ,business - Published
- 2010
10. Comparison between cytochrome P450 (CYP) content and relative activity approaches to scaling from cDNA-expressed CYPs to human liver microsomes: ratios of accessory proteins as sources of discrepancies between the approaches
- Author
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K, Venkatakrishnan, L L, von Moltke, M H, Court, J S, Harmatz, C L, Crespi, and D J, Greenblatt
- Subjects
Adult ,Male ,DNA, Complementary ,Adolescent ,Immunochemistry ,Blotting, Western ,Proteins ,In Vitro Techniques ,Isoenzymes ,Cytochromes b5 ,Cytochrome P-450 Enzyme System ,Child, Preschool ,Data Interpretation, Statistical ,Microsomes, Liver ,Humans ,Female ,Lymphocytes ,Child ,Algorithms ,Relative Biological Effectiveness - Abstract
Relative activity factors (RAFs) and immunoquantified levels of cytochrome P450 (CYP) isoforms both have been proposed as scaling factors for the prediction of hepatic drug metabolism from studies using cDNA-expressed CYPs. However, a systematic comparison of the two approaches, including possible mechanisms underlying differences, is not available. In this study, RAFs determined for CYPs 1A2, 2B6, 2C19, 2D6, and 3A4 in 12 human livers using lymphoblast-expressed enzymes were compared to immunoquantified protein levels. 2C19, 2D6, and 3A4 RAFs were similar to immunoquantified enzyme levels. In contrast, 1A2 RAFs were 5- to 20-fold higher than CYP1A2 content, and the RAF:content ratio was positively correlated with the molar ratio of NADPH:CYP oxidoreductase (OR) to CYP1A2. The OR:CYP1A2 ratio in lymphoblast microsomes was 92-fold lower than in human liver microsomes. Reconstitution experiments demonstrated a 10- to 20-fold lower activity at OR:CYP1A2 ratios similar to those in lymphoblasts, compared with those in human livers. CYP2B6-containing lymphoblast microsomes had 29- and 13-fold lower OR:CYP and cytochrome b(5):CYP ratios, respectively, than did liver microsomes and yielded RAFs that were 6-fold higher than CYP2B6 content. Use of metabolic rates from cDNA-expressed CYPs containing nonphysiologic concentrations of electron-transfer proteins (relative to human liver microsomes) in conjunction with hepatic CYP contents may lead to incorrect predictions of liver microsomal rates and relative contributions of individual isoforms. Scaling factors used in bridging the gap between expression systems and liver microsomes should not only incorporate relative hepatic abundance of individual CYPs but also account for differences in activity per unit enzyme in the two systems.
- Published
- 2000
11. CYP2B6 mediates the in vitro hydroxylation of bupropion: potential drug interactions with other antidepressants
- Author
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L M, Hesse, K, Venkatakrishnan, M H, Court, L L, von Moltke, S X, Duan, R I, Shader, and D J, Greenblatt
- Subjects
Dose-Response Relationship, Drug ,Oxidoreductases, N-Demethylating ,Triazoles ,Hydroxylation ,Antibodies ,Piperazines ,Isoenzymes ,Cytochrome P-450 CYP2B6 ,Kinetics ,Paroxetine ,Cytochrome P-450 Enzyme System ,Fluvoxamine ,Fluoxetine ,Sertraline ,Microsomes, Liver ,Antidepressive Agents, Second-Generation ,Humans ,Drug Interactions ,Aryl Hydrocarbon Hydroxylases ,Bupropion ,Biotransformation ,Chromatography, High Pressure Liquid - Abstract
The in vitro biotransformation of bupropion to hydroxybupropion was studied in human liver microsomes and microsomes containing heterologously expressed human cytochromes P450 (CYP). The mean (+/-S.E.) K(m) in four human liver microsomes was 89 (+/-14) microM. In microsomes containing cDNA-expressed CYPs, hydroxybupropion formation was mediated only by CYP2B6 at 50 microM bupropion (K(m) 85 microM). A CYP2B6 inhibitory antibody produced more than 95% inhibition of bupropion hydroxylation in four human livers. Bupropion hydroxylation activity at 250 microM was highly correlated with S-mephenytoin N-demethylation activity (yielding nirvanol), another CYP2B6-mediated reaction, in a panel of 32 human livers (r = 0.94). The CYP2B6 content of 12 human livers highly correlated with bupropion hydroxylation activity (r = 0.96). Thus bupropion hydroxylation is mediated almost exclusively by CYP2B6 and can serve as an index reaction reflecting activity of this isoform. IC(50) values for inhibition of a CYP2D6 index reaction (dextromethorphan O-demethylation) by bupropion and hydroxybupropion were 58 and 74 microM, respectively. This suggests a low inhibitory potency versus CYP2D6, the clinical importance of which is not established. Since bupropion is frequently coadministered with other antidepressants, IC(50) values (microM) for inhibition of bupropion hydroxylation were determined as follows: paroxetine (1.6), fluvoxamine (6.1), sertraline (3.2), desmethylsertraline (19.9), fluoxetine (59.5), norfluoxetine (4.2), and nefazodone (25.4). Bupropion hydroxylation was only weakly inhibited by venlafaxine, O-desmethylvenlafaxine, citalopram, and desmethylcitalopram. The inhibition of bupropion hydroxylation in vitro by a number of newer antidepressants suggests the potential for clinical drug interactions.
- Published
- 2000
12. Microsomal binding of amitriptyline: effect on estimation of enzyme kinetic parameters in vitro
- Author
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K, Venkatakrishnan, L L, von Moltke, R S, Obach, and D J, Greenblatt
- Subjects
Amitriptyline ,Antidepressive Agents, Tricyclic ,In Vitro Techniques ,Leukemia, Lymphoid ,Mixed Function Oxygenases ,Cytochrome P-450 CYP2C19 ,Kinetics ,Cytochrome P-450 Enzyme System ,Dealkylation ,Microsomes, Liver ,Tumor Cells, Cultured ,Cytochrome P-450 CYP3A ,Humans ,Aryl Hydrocarbon Hydroxylases ,Dialysis ,Algorithms ,Biotransformation - Abstract
The effect of binding of amitriptyline to human liver microsomes and to microsomes from human B-lymphoblastoid cells on the estimation of enzyme kinetic parameters describing N-demethylation to nortriptyline was investigated using a combination of microsomal binding and in vitro enzyme kinetic studies. Quantitative binding in both matrices increased with higher microsomal protein concentrations (free fractions 0.88-0.32 at 100-500 microg protein/ml in human liver microsomes and 0.82-0.26 at 250-1000 microg protein/ml in microsomes from B-lymphoblastoid cells) and was independent of amitriptyline concentration over a concentration range of 0.2 to 200 microM. Addition of heat-inactivated microsomal protein (50-450 microg/ml) to native human liver microsomes (50 microg/ml) reduced the amitriptyline N-demethylation rate in a protein concentration dependent manner. This effect was greater at lower substrate concentrations and was overcome by saturating concentrations of substrate, thereby decreasing the apparent affinities of the high- and low-affinity components of the N-demethylation process, with minimal effect on the net V(max). Addition of metabolically inactive microsomes from untransfected human lymphoblastoid cells (750 microg/ml) to CYP2C19 (250 microg/ml protein) increased the apparent K(m) value for amitriptyline N-demethylation by 3.5-fold and increased the uncompetitive substrate inhibition constant (K(s)) by 2.2-fold, making substrate inhibition essentially undetectable. A similar effect was seen with CYP3A4, with a 1.8-fold increase in the S(50) (substrate concentration at which half-maximal velocity of a Hill enzyme is achieved). Microsomal binding did not alter the V(max) of either CYP isoform to any appreciable extent. These findings emphasize the importance of incorporating microsomal binding in the estimation of enzyme kinetic parameters in vitro and making appropriate corrections for unbound drug concentrations.
- Published
- 2000
13. A Novel Technique for Measurement of Vibration Using Acousto Optic Modulator (AOM)
- Author
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B. K. A. Ngoi and K. Venkatakrishnan
- Abstract
A novel method for the measurement of vibration using an acousto optic modulator (AOM) is described. Previous methods generally rely on holographic (off-line measurement) and laser Doppler vibrometers (on line measurement). This method shows a new direction of vibration measurement using AOM rather than relying on laser Doppler vibrometer and laser Doppler displacement meter for on-line vibration measurement. A method of obtaining resolution in the range of sub-nanometer is proposed. The technique proposed not only projects a novel technique but also brings to light the possible application of AOM.
- Published
- 1998
14. 618 Integrated Analysis of Pharmacokinetics and Exposure–Adverse Event Relationship of the Investigational Agent MLN0128 to Guide Dose and Schedule Selection for Further Clinical Investigation
- Author
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P.J. Lipman, C. Patel, and K. Venkatakrishnan
- Subjects
Cancer Research ,Schedule ,medicine.medical_specialty ,Oncology ,Pharmacokinetics ,business.industry ,Clinical investigation ,medicine ,Pharmacology ,Adverse effect ,Intensive care medicine ,business ,Selection (genetic algorithm) - Published
- 2012
15. High repetition rate femtosecond laser forming sub-10 µm diameter interconnection vias
- Author
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Senthilnathan Panchatsharam, Bo Tan, and K Venkatakrishnan
- Subjects
Microvia ,Interconnection ,Materials science ,Laser ablation ,Acoustics and Ultrasonics ,Silicon ,business.industry ,medicine.medical_treatment ,chemistry.chemical_element ,Condensed Matter Physics ,Laser ,Ablation ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,law.invention ,Optics ,Machining ,chemistry ,law ,Femtosecond ,medicine ,business - Abstract
Laser ablative microvia formation has been widely accepted as an effective manufacturing method for interconnect via formation. Current conventional nanosecond laser microvia formation has reached its limit in terms of minimum via diameter and machining quality. Femtosecond laser has been investigated intensively for its superior machining quality and capability of producing much smaller features. However, the traditional femtosecond laser has very low power and is thus unable to meet the throughput requirement. In this paper we report ablative microvia formation using femtosecond lasers at megahertz repetition rates. Laser ablation was demonstrated for the first time for sub-10 µm interconnection via drilling at a throughput of 10 000 vias per second. A systematic study of the influence of a high repetition rate in femtosecond laser micromachining of silicon was carried out. The experiments were performed using an Yb-doped fibre amplified/oscillator laser with 1030 nm wavelength in an air environment. The effects of a high repetition rate on microvia formation were observed at ~300 fs for silicon substrates. Laser parameters along with threshold energy, via diameter, ablation depth, ablation rate and via quality were studied in detail to accentuate the need of femtosecond lasers for forming sub-10 µm diameter microvias. The experimental results show that femtosecond laser pulses with high repetition rates show unequivocally the advantages of short-pulse laser ablation for high-precision applications in micrometre-scale dimensions.
- Published
- 2009
16. CYP3A4 is the major CYP isoform mediating the in vitro hydroxylation and demethylation of flunitrazepam.
- Author
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M, Hesse L, K, Venkatakrishnan, L, von Moltke L, I, Shader R, and J, Greenblatt D
- Abstract
The kinetics of flunitrazepam (FNTZ) N-demethylation to desmethylflunitrazepam (DM FNTZ), and 3-hydroxylation to 3-hydroxyflunitrazepam (3-OH FNTZ), were studied in human liver microsomes and in microsomes containing heterologously expressed individual human CYPs. FNTZ was N-demethylated by cDNA-expressed CYP2A6 (K(m) = 1921 microM), CYP2B6 (K(m) = 101 microM), CYP2C9 (K(m) = 50 microM), CYP2C19 (K(m) = 60 microM), and CYP3A4 (K(m) = 155 microM), and 3-hydroxylated by cDNA-expressed CYP2A6 (K(m) = 298 microM) and CYP3A4 (K(m) = 286 microM). The 3-hydroxylation pathway was predominant in liver microsomes, accounting for more than 80% of intrinsic clearance compared with the N-demethylation pathway. After adjusting for estimated relative abundance, CYP3A accounted for the majority of intrinsic clearance via both pathways. This finding was supported by chemical inhibition studies in human liver microsomes. Formation of 3-OH FNTZ was reduced to 10% or less of control values by ketoconazole (IC(50) = 0.11 microM) and ritonavir (IC(50) = 0.041 microM). Formation of DM FNTZ was inhibited to 40% of control velocity by 2.5 microM ketoconazole and to 30% of control by 2.5 microM ritonavir. Neither 3-OH FNTZ nor DM FNTZ formation was inhibited to less than 85% of control activity by alpha-naphthoflavone (CYP1A2), sulfaphenazole (CYP2C9), omeprazole (CYP2C19), or quinidine (CYP2D6). Thus, CYP-dependent FNTZ biotransformation, like that of many benzodiazepine derivatives, is mediated mainly by CYP3A. Clinical interactions of FNTZ with CYP3A inhibitors can be anticipated.
- Published
- 2001
17. CYP2B6 mediates the in vitro hydroxylation of bupropion: potential drug interactions with other antidepressants.
- Author
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M, Hesse L, K, Venkatakrishnan, H, Court M, L, von Moltke L, X, Duan S, I, Shader R, and J, Greenblatt D
- Abstract
The in vitro biotransformation of bupropion to hydroxybupropion was studied in human liver microsomes and microsomes containing heterologously expressed human cytochromes P450 (CYP). The mean (+/-S.E.) K(m) in four human liver microsomes was 89 (+/-14) microM. In microsomes containing cDNA-expressed CYPs, hydroxybupropion formation was mediated only by CYP2B6 at 50 microM bupropion (K(m) 85 microM). A CYP2B6 inhibitory antibody produced more than 95% inhibition of bupropion hydroxylation in four human livers. Bupropion hydroxylation activity at 250 microM was highly correlated with S-mephenytoin N-demethylation activity (yielding nirvanol), another CYP2B6-mediated reaction, in a panel of 32 human livers (r = 0.94). The CYP2B6 content of 12 human livers highly correlated with bupropion hydroxylation activity (r = 0.96). Thus bupropion hydroxylation is mediated almost exclusively by CYP2B6 and can serve as an index reaction reflecting activity of this isoform. IC(50) values for inhibition of a CYP2D6 index reaction (dextromethorphan O-demethylation) by bupropion and hydroxybupropion were 58 and 74 microM, respectively. This suggests a low inhibitory potency versus CYP2D6, the clinical importance of which is not established. Since bupropion is frequently coadministered with other antidepressants, IC(50) values (microM) for inhibition of bupropion hydroxylation were determined as follows: paroxetine (1.6), fluvoxamine (6.1), sertraline (3.2), desmethylsertraline (19.9), fluoxetine (59.5), norfluoxetine (4.2), and nefazodone (25.4). Bupropion hydroxylation was only weakly inhibited by venlafaxine, O-desmethylvenlafaxine, citalopram, and desmethylcitalopram. The inhibition of bupropion hydroxylation in vitro by a number of newer antidepressants suggests the potential for clinical drug interactions.
- Published
- 2000
18. CYP2C9 is a principal low-affinity phenacetin O-deethylase: fluvoxamine is not a specific CYP1A2 inhibitor.
- Author
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K, Venkatakrishnan, L, von Moltke L, and J, Greenblatt D
- Published
- 1999
19. Micro-fluidic channel fabrication via two-photon absorption (TPA) polymerization assisted ablation.
- Author
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S Jariwala, B Tan, and K Venkatakrishnan
- Subjects
MICROFLUIDICS ,TWO-photon absorbing materials ,POLYMERIZATION ,PHOTORESISTS ,LITHOGRAPHY techniques ,MANUFACTURING processes - Abstract
Two-photon absorption (TPA) polymerization assisted ablation is a simple, fast and repeatable method for fabricating micro-fluidic channels. Since it is a maskless method, it is relatively inexpensive and faster than other conventional lithography techniques. Unlike direct ablation, TPA assisted ablation requires significantly less energy; as a result, it has greater control over the desired feature size and spatial resolution. In this work, we also show that ORMOCER has pronounced TPA assisted ablation threshold behavior, which is related to laser parameters such as spot radius, repetition rate and scan speed, in addition to the chemical properties of the photoresist. By manipulating these parameters, any two-dimensional-shaped micro-fluidic channels with desired channel width and depth can be fabricated. [ABSTRACT FROM AUTHOR]
- Published
- 2009
- Full Text
- View/download PDF
20. High repetition rate femtosecond laser forming sub-10?µm diameter interconnection vias.
- Author
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B Tan, S Panchatsharam, and K Venkatakrishnan
- Subjects
FEMTOSECOND lasers ,LASER ablation ,INTEGRATED circuit interconnections ,MICROMACHINING ,MANUFACTURING processes ,LASER drilling ,SILICON ,PHYSICS experiments - Abstract
Laser ablative microvia formation has been widely accepted as an effective manufacturing method for interconnect via formation. Current conventional nanosecond laser microvia formation has reached its limit in terms of minimum via diameter and machining quality. Femtosecond laser has been investigated intensively for its superior machining quality and capability of producing much smaller features. However, the traditional femtosecond laser has very low power and is thus unable to meet the throughput requirement. In this paper we report ablative microvia formation using femtosecond lasers at megahertz repetition rates. Laser ablation was demonstrated for the first time for sub-10 um interconnection via drilling at a throughput of 10 000 vias per second. A systematic study of the influence of a high repetition rate in femtosecond laser micromachining of silicon was carried out. The experiments were performed using an Yb-doped fibre amplified/oscillator laser with 1030 nm wavelength in an air environment. The effects of a high repetition rate on microvia formation were observed at [?]300 fs for silicon substrates. Laser parameters along with threshold energy, via diameter, ablation depth, ablation rate and via quality were studied in detail to accentuate the need of femtosecond lasers for forming sub-10 um diameter microvias. The experimental results show that femtosecond laser pulses with high repetition rates show unequivocally the advantages of short-pulse laser ablation for high-precision applications in micrometre-scale dimensions. [ABSTRACT FROM AUTHOR]
- Published
- 2009
- Full Text
- View/download PDF
21. Profiling Breast Tumor Heterogeneity and Identifying Breast Cancer Subtypes Through Tumor-Associated Immune Cell Signatures and Immuno Nano Sensors.
- Author
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Ishwar D, Premachandran S, Das S, Venkatakrishnan K, and Tan B
- Abstract
Breast cancer is a complex and heterogeneous disease with varying cellular, genetic, epigenetic, and molecular expressions. The detection of intratumor heterogeneity in breast cancer poses significant challenges due to its complex multifaceted characteristics, yet its identification is crucial for guiding effective treatment decisions and understanding the disease progression. Currently, there exists no method capable of capturing the full extent of breast tumor heterogeneity. In this study, the aim is to identify and characterize metabolic heterogeneity in breast tumors using immune cells and an ultrafast laser-fabricated Immuno Nano Sensor. Combining spectral markers from both Natural Killer (NK) and T cells, a machine-learning approach is implemented to distinguish cancer from healthy samples, identify primary versus metastatic tumors, and determine estrogen receptor (ER)/progesterone receptor (PR) status at the single-cell level. The platform successfully distinguished heterogeneous breast cancer samples from healthy individuals, achieving 97.8% sensitivity and 92.2% specificity, and accurately identified primary tumors from metastatic tumors. Characteristic spectral signatures allow for discrimination between ER/PR-positive and negative tumors with 97.5% sensitivity. This study demonstrates the potential of immune cell-based metabolic profiling in providing a comprehensive assessment of breast tumor heterogeneity and paving the way for minimally invasive liquid biopsy approaches in breast cancer diagnosis and management., (© 2024 The Author(s). Small published by Wiley‐VCH GmbH.)
- Published
- 2024
- Full Text
- View/download PDF
22. Establishing a physiologically based pharmacokinetic framework for aldehyde oxidase and dual aldehyde oxidase-CYP substrates.
- Author
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Izat N, Bolleddula J, Carione P, Huertas Valentin L, Jones RS, Kulkarni P, Moss D, Peterkin VC, Tian DD, Treyer A, Venkatakrishnan K, Zientek MA, Barber J, Houston JB, Galetin A, and Scotcher D
- Abstract
Aldehyde oxidase (AO) contributes to the clearance of many approved and investigational small molecule drugs, which are often dual substrates of AO and drug-metabolizing enzymes such as cytochrome P450s (CYPs). As such, the lack of established framework for quantitative translation of the clinical pharmacologic correlates of AO-mediated clearance represents an unmet need. This study aimed to evaluate the utility of physiologically based pharmacokinetic (PBPK) modeling in the development of AO and dual AO-CYP substrates. PBPK models were developed for capmatinib, idelalisib, lenvatinib, zaleplon, ziprasidone, and zoniporide, incorporating in vitro functional data from human liver subcellular fractions and human hepatocytes. Prediction of metabolic elimination with/without the additional empirical scaling factors (ESFs) was assessed. Clinical pharmacokinetics, human mass balance, and drug-drug interaction (DDI) studies with CYP3A4 modulators, where available, were used to refine/verify the models. Due to the lack of clinically significant AO-DDIs with known AO inhibitors, the fraction metabolized by AO (fm
AO ) was verified indirectly. Clearance predictions were improved by using ESFs (GMFE ≤1.4-fold versus up to fivefold with physiologically-based scaling only). Observed fmi from mass balance studies were crucial for model verification/refinement, as illustrated by capmatinib, where the fmAO (40%) was otherwise underpredicted up to fourfold. Subsequently, independent DDI studies with ketoconazole, itraconazole, rifampicin, and carbamazepine verified the fmCYP3A4 , with predicted ratios of the area under the concentration-time curve (AUCR) within 1.5-fold of the observations. In conclusion, this study provides a novel PBPK-based framework for predicting AO-mediated pharmacokinetics and quantitative assessment of clinical DDI risks for dual AO-CYP substrates within a totality-of-evidence approach., (© 2024 The Author(s). CPT: Pharmacometrics & Systems Pharmacology published by Wiley Periodicals LLC on behalf of American Society for Clinical Pharmacology and Therapeutics.)- Published
- 2024
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23. The Potential of Disease Progression Modeling to Advance Clinical Development and Decision Making.
- Author
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Starling MS, Kehoe L, Burnett BK, Green P, Venkatakrishnan K, and Madabushi R
- Abstract
While some model-informed drug development frameworks are well recognized as enabling clinical trials, the value of disease progression modeling (DPM) in impacting medical product development has yet to be fully realized. The Clinical Trials Transformation Initiative assembled a diverse project team from across the patient, academic, regulatory, and industry sectors of practice to advance the use of DPM for decision making in clinical trials and medical product development. This team conducted a scoping review to explore current applications of DPM and convened a multi-stakeholder expert meeting to discuss its value in medical product development. In this article, we present the scoping review and expert meeting output and propose key questions that medical product developers and regulators may use to inform clinical development strategy, appreciate the therapeutic context and endpoint selection, and optimize trial design with disease progression models. By expanding awareness of the unique value of DPM, this article does not aim to be technical in nature but rather aims to highlight the potential of DPM to improve the quality and efficiency of medical product development., (© 2024 The Author(s). Clinical Pharmacology & Therapeutics published by Wiley Periodicals LLC on behalf of American Society for Clinical Pharmacology and Therapeutics.)
- Published
- 2024
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24. Oncology Combination Drug Development Strategies for Project Optimus.
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Yap TA, Bullock J, Chong S, Doyle MK, Hussain A, Kline J, Manon A, Venkatakrishnan K, and Upreti VV
- Abstract
The Project Optimus initiative from the FDA introduced a new dose optimization and selection paradigm in oncology drug development. The FDA has outlined approaches to dose optimization for single agents, but multiple oncology drugs are being developed for use in combination with other therapies. Dose optimization in the context of combination drug development is complex and requires a case-by-case approach. It necessitates commitment to the totality of available evidence, leveraging all relevant data on mechanism of action, nonclinical and clinical pharmacology, safety, and principles of model-informed drug development. In this article, we outline key considerations for sponsors and investigators pursuing dose optimization with combinatorial regimens. We illustrate important strategies for dose optimization in the combination setting using a range of hypothetical case examples that represent typical drug development scenarios. Close discussions and collaboration with regulators regarding the optimal approaches to these scenarios will continue to be critical.
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- 2024
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25. Asia-inclusive drug development leveraging principles of ICH E5 and E17 guidelines: Case studies illustrating quantitative clinical pharmacology as a foundational enabler.
- Author
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Lu H, Klopp-Schulze L, Mukker JK, Li D, Kuroki Y, Bolleddula J, Terranova N, Goteti K, Gao W, Strotmann R, Dong J, and Venkatakrishnan K
- Subjects
- Humans, Asia, Pharmacology, Clinical methods, Clinical Trials as Topic, Guidelines as Topic, Drugs, Investigational pharmacology, Drug Development methods
- Abstract
With the International Conference on Harmonization of Technical Requirements for Pharmaceuticals for Human Use (ICH) E17 guidelines in effect from 2018, the design of Asia-inclusive multiregional clinical trials (MRCTs) has been streamlined, thereby enabling efficient simultaneous global development. Furthermore, with the recent regulatory reforms in China and its drug administration joining the ICH as a full regulatory member, early participation of China in the global clinical development of novel investigational drugs is now feasible. This would also allow for inclusion of the region in the geographic footprint of pivotal MRCTs leveraging principles of the ICH E5 and E17. Herein, we describe recent case examples of model-informed Asia-inclusive global clinical development in the EMD Serono portfolio, as applied to the ataxia telangiectasia and Rad3-related inhibitors, tuvusertib and berzosertib (oncology), the toll-like receptor 7/8 antagonist, enpatoran (autoimmune diseases), the mesenchymal-epithelial transition factor inhibitor tepotinib (oncology), and the antimetabolite cladribine (neuroimmunological disease). Through these case studies, we illustrate pragmatic approaches to ethnic sensitivity assessments and the application of a model-informed drug development toolkit including population pharmacokinetic/pharmacodynamic modeling and pharmacometric disease progression modeling and simulation to enable early conduct of Asia-inclusive MRCTs. These examples demonstrate the value of a Totality of Evidence approach where every patient's data matter for de-risking ethnic sensitivity to inter-population variations in drug- and disease-related intrinsic and extrinsic factors, enabling inclusive global development strategies and timely evidence generation for characterizing benefit/risk of the proposed dosage in Asian populations., (© 2024 The Author(s). Clinical and Translational Science published by Wiley Periodicals LLC on behalf of American Society for Clinical Pharmacology and Therapeutics.)
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- 2024
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26. Model-informed Evidence for Clinical Non-inferiority of Every-2-Weeks Versus Standard Weekly Dosing Schedule of Cetuximab in Metastatic Colorectal Cancer.
- Author
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Milenković-Grišić AM, Hayes S, Farrell C, Kuroki Y, Bertolino M, Venkatakrishnan K, and Girard P
- Subjects
- Humans, Neoplasm Metastasis, Male, Female, Middle Aged, Equivalence Trials as Topic, Computer Simulation, Aged, Cetuximab administration & dosage, Cetuximab pharmacokinetics, Cetuximab therapeutic use, Colorectal Neoplasms drug therapy, Colorectal Neoplasms pathology, Colorectal Neoplasms genetics, Drug Administration Schedule, Antineoplastic Agents, Immunological administration & dosage, Antineoplastic Agents, Immunological pharmacokinetics, Antineoplastic Agents, Immunological therapeutic use, Models, Biological
- Abstract
Cetuximab was initially developed and approved as a first-line treatment in patients with unresectable metastatic colorectal cancer (mCRC) for weekly administration (250 mg/m
2 Q1W with 400 mg/m2 loading dose). An every-2-weeks schedule (500 mg/m2 Q2W) was approved recently by several health authorities. Being synchronized with chemotherapy, Q2W administration should improve patients' convenience and healthcare resource utilization. Herein, we present evidence of non-inferiority of Q2W cetuximab, compared with Q1W dosing using pharmacometrics modeling and clinical trial simulation (CTS). Pooled data from five phase I-III clinical trials in 852 patients with KRAS wild-type mCRC treated with Q1W or Q2W cetuximab were modeled using a population exposure-tumor size (TS) model linked to overall survival (OS); exposure was derived from a previously established population pharmacokinetic model. A semi-mechanistic TS model adapted from the Claret model incorporated killing rate proportional to cetuximab area under the concentration-time curve over 2 weeks (AUC) with Eastern Cooperative Oncology Group (ECOG) status as covariate on baseline TS. The OS was modeled with Weibull hazard using ECOG, baseline TS, primary tumor location, and predicted percent change in TS at 8 weeks as covariates. Model-based simulations revealed indistinguishable early tumor shrinkage and survival between Q2W vs. Q1W cetuximab. CTS evaluated OS non-inferiority (predefined margin of 1.25) in 1,000 trials, each with 2,000 virtual patients receiving Q2W or Q1W cetuximab (1:1), and demonstrated non-inferiority in 94% of cases. Taken together, these analyses provide model-based evidence for clinical non-inferiority of Q2W vs. Q1W cetuximab in mCRC with potential benefits to patients and healthcare providers., (© 2024 Emd Serono Research & Development Institute, Inc. Clinical Pharmacology & Therapeutics published by Wiley Periodicals LLC on behalf of American Society for Clinical Pharmacology and Therapeutics.)- Published
- 2024
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27. Explainable machine learning prediction of edema adverse events in patients treated with tepotinib.
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Amato F, Strotmann R, Castello R, Bruns R, Ghori V, Johne A, Berghoff K, Venkatakrishnan K, and Terranova N
- Subjects
- Humans, Female, Male, Middle Aged, Aged, Lung Neoplasms drug therapy, Clinical Trials, Phase II as Topic, Pyrimidines adverse effects, Pyrimidines administration & dosage, Clinical Trials, Phase I as Topic, Adult, Antineoplastic Agents adverse effects, Protein Kinase Inhibitors adverse effects, Piperidines, Pyridazines, Edema chemically induced, Machine Learning, Carcinoma, Non-Small-Cell Lung drug therapy
- Abstract
Tepotinib is approved for the treatment of patients with non-small-cell lung cancer harboring MET exon 14 skipping alterations. While edema is the most prevalent adverse event (AE) and a known class effect of MET inhibitors including tepotinib, there is still limited understanding about the factors contributing to its occurrence. Herein, we apply machine learning (ML)-based approaches to predict the likelihood of occurrence of edema in patients undergoing tepotinib treatment, and to identify factors influencing its development over time. Data from 612 patients receiving tepotinib in five Phase I/II studies were modeled with two ML algorithms, Random Forest, and Gradient Boosting Trees, to predict edema AE incidence and severity. Probability calibration was applied to give a realistic estimation of the likelihood of edema AE. Best model was tested on follow-up data and on data from clinical studies unused while training. Results showed high performances across all the tested settings, with F1 scores up to 0.961 when retraining the model with the most relevant covariates. The use of ML explainability methods identified serum albumin as the most informative longitudinal covariate, and higher age as associated with higher probabilities of more severe edema. The developed methodological framework enables the use of ML algorithms for analyzing clinical safety data and exploiting longitudinal information through various covariate engineering approaches. Probability calibration ensures the accurate estimation of the likelihood of the AE occurrence, while explainability tools can identify factors contributing to model predictions, hence supporting population and individual patient-level interpretation., (© 2024 The Author(s). Clinical and Translational Science published by Wiley Periodicals LLC on behalf of American Society for Clinical Pharmacology and Therapeutics.)
- Published
- 2024
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28. Getting the Dosage Right: A Vital Role for Clinical Pharmacology in the Era of Precision Medicine.
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Minichmayr IK, Shebley M, van der Graaf PH, and Venkatakrishnan K
- Subjects
- Humans, Dose-Response Relationship, Drug, Drug Dosage Calculations, Pharmaceutical Preparations administration & dosage, Precision Medicine methods, Pharmacology, Clinical methods
- Published
- 2024
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29. Dose Optimization in Oncology Drug Development: An International Consortium for Innovation and Quality in Pharmaceutical Development White Paper.
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Samineni D, Venkatakrishnan K, Othman AA, Pithavala YK, Poondru S, Patel C, Vaddady P, Ankrom W, Ramanujan S, Budha N, Wu M, Haddish-Berhane N, Fritsch H, Hussain A, Kanodia J, Li M, Li M, Melhem M, Parikh A, Upreti VV, and Gupta N
- Subjects
- Humans, United States, United States Food and Drug Administration, Maximum Tolerated Dose, White, Drug Development methods, Antineoplastic Agents administration & dosage, Antineoplastic Agents adverse effects, Dose-Response Relationship, Drug, Neoplasms drug therapy
- Abstract
The landscape of oncology drug development has witnessed remarkable advancements over the last few decades, significantly improving clinical outcomes and quality of life for patients with cancer. Project Optimus, introduced by the U.S. Food and Drug Administration, stands as a groundbreaking endeavor to reform dose selection of oncology drugs, presenting both opportunities and challenges for the field. To address complex dose optimization challenges, an Oncology Dose Optimization IQ Working Group was created to characterize current practices, provide recommendations for improvement, develop a clinical toolkit, and engage Health Authorities. Historically, dose selection for cytotoxic chemotherapeutics has focused on the maximum tolerated dose, a paradigm that is less relevant for targeted therapies and new treatment modalities. A survey conducted by this group gathered insights from member companies regarding industry practices in oncology dose optimization. Given oncology drug development is a complex effort with multidimensional optimization and high failure rates due to lack of clinically relevant efficacy, this Working Group advocates for a case-by-case approach to inform the timing, specific quantitative targets, and strategies for dose optimization, depending on factors such as disease characteristics, patient population, mechanism of action, including associated resistance mechanisms, and therapeutic index. This white paper highlights the evolving nature of oncology dose optimization, the impact of Project Optimus, and the need for a tailored and evidence-based approach to optimize oncology drug dosing regimens effectively., (© 2024 The Authors. Clinical Pharmacology & Therapeutics published by Wiley Periodicals LLC on behalf of American Society for Clinical Pharmacology and Therapeutics.)
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- 2024
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30. Establishing a Remote Blood Pressure Monitoring Program Through the First Year Postpartum After Pregnancy-Induced Hypertension.
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Reddy A, Hauspurg A, Venkatakrishnan K, Pippi D, Lemon L, Berlacher K, Jeyabalan A, and Countouris M
- Published
- 2024
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31. Fabrication of Isotope-Enriched Nanostructures Using Ultrafast Laser Pulses under Ambient Conditions for Biomolecular Sensing.
- Author
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Premachandran S, Manickam S, Tan B, and Venkatakrishnan K
- Subjects
- Isotopes chemistry, Carbon Isotopes chemistry, Lasers, Nanostructures chemistry, Spectrum Analysis, Raman methods
- Abstract
Recent advances in the use of stable isotopes necessitate novel synthesis techniques for isotope separation and enrichment that are scalable and offer high throughput. Stable-isotope-enriched nanostructures can offer unique advantages as nanomedicines, safe tracers, and labels and are critical for applications in various industrial processes, metabolic research, and medicine. So far, there exists no method to synthesize miniature isotope-enriched materials at the nanoscale. In this study, an ultrafast Laser-induced isotope enrichment at nanoscale (LIIEN) is put forward to synthesize isotope-enriched nanostructures, eliminating the need for large equipment and expenses, thereby demonstrating a lab-scale isotope enrichment process. A significant isotope enrichment for Carbon nanostructures is observed. The isotope enrichment can be attributed to the redistribution of isotope ions in the plasma plume explained by the plasma centrifuge model. The LIIEN synthesized structures exhibit excellent Surface-Enhanced Raman Scattering (SERS) signal enhancement and reproducibility, making them potential candidates for SERS-based biomolecule sensing. This technique is an efficient method to fabricate nanosized isotope-enriched structures of characteristic properties by carefully tuning laser parameters at ambient conditions., (© 2024 Wiley‐VCH GmbH.)
- Published
- 2024
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32. Postpartum Ambulatory Blood Pressure Patterns Following New-Onset Hypertensive Disorders of Pregnancy.
- Author
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Hauspurg A, Venkatakrishnan K, Collins L, Countouris M, Larkin J, Quinn B, Kabir N, Catov J, Lemon L, and Simhan H
- Subjects
- Humans, Female, Pregnancy, Adult, Risk Factors, Blood Pressure physiology, Patient Readmission statistics & numerical data, Hypertension physiopathology, Hypertension epidemiology, Pre-Eclampsia physiopathology, Pre-Eclampsia epidemiology, Cohort Studies, Hypertension, Pregnancy-Induced physiopathology, Hypertension, Pregnancy-Induced epidemiology, Postpartum Period, Blood Pressure Monitoring, Ambulatory
- Abstract
Importance: After a hypertensive disorder of pregnancy, hypertension can worsen in the postpartum period following hospital discharge. Risk factors for ongoing hypertension and associated outcomes have not been well characterized., Objective: To identify risk factors and characterize outcomes for individuals with ongoing hypertension and severe hypertension following hospital discharge post partum through a hospital system's remote blood pressure (BP) management program., Design, Setting, and Participants: This cohort study involved a population-based sample of individuals with a new-onset hypertensive disorder of pregnancy (preeclampsia or gestational hypertension) and no prepregnancy hypertension who delivered between September 2019 and June 2021. Participants were enrolled in a remote BP monitoring and management program at a postpartum unit at a referral hospital. Data analysis was performed from August 2021 to January 2023., Exposure: Inpatient postpartum BP categories., Main Outcomes and Measures: The primary outcomes were readmission and emergency department visits within the first 6 weeks post partum. Logistic regression was used to model adjusted odds ratios (aORs) and 95% CIs., Results: Of 2705 individuals in the cohort (mean [SD] age, 29.8 [5.7] years), 2214 (81.8%) had persistent hypertension post partum after hospital discharge, 382 (14.1%) developed severe hypertension after discharge, and 610 (22.6%) had antihypertensive medication initiated after discharge. Individuals with severe hypertension had increased odds of postpartum emergency department visits (aOR, 1.85; 95% CI, 1.17-2.92) and hospital readmissions (aOR, 6.75; 95% CI, 3.43-13.29) compared with individuals with BP normalization. When inpatient postpartum BP categories were compared with outpatient home BP trajectories to inform optimal thresholds for inpatient antihypertensive medication initiation, there was significant overlap between postdischarge BP trajectories among those with inpatient systolic BP greater than or equal to 140 to 149 mm Hg and/or diastolic BP greater than or equal to 90 to 99 mm Hg and those with systolic BP greater than or equal to 150 mm Hg and/or diastolic BP greater than or equal to 100 mm Hg., Conclusions and Relevance: This cohort study found that more than 80% of individuals with hypertensive disorders of pregnancy had ongoing hypertension after hospital discharge, with approximately 14% developing severe hypertension. These data support the critical role of remote BP monitoring programs and highlight the need for improved tools for risk stratification and consideration of liberalization of thresholds for medication initiation post partum.
- Published
- 2024
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33. A phase 1 study to assess the absolute bioavailability, mass balance, pharmacokinetics, metabolism, and excretion of [ 14 C]-mobocertinib, an oral inhibitor of EGFR exon 20 insertion mutations, in healthy participants.
- Author
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Hanley MJ, Zhang S, Griffin R, Zhu SX, Fram RJ, Lin J, Venkatakrishnan K, and Gupta N
- Subjects
- Humans, Male, Adult, Administration, Oral, Middle Aged, Healthy Volunteers, Young Adult, Exons, Mutagenesis, Insertional, Carbon Radioisotopes, Aniline Compounds, Indoles, Pyrimidines, ErbB Receptors antagonists & inhibitors, ErbB Receptors genetics, Biological Availability, Protein Kinase Inhibitors pharmacokinetics, Protein Kinase Inhibitors administration & dosage
- Abstract
Mobocertinib (TAK-788) is a first-in-class oral epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor that received accelerated approval for the treatment of patients with non-small cell lung cancer with EGFR exon 20 insertion mutations previously treated with platinum-based chemotherapy. This phase 1, 2-period, study was conducted to assess the absolute bioavailability of mobocertinib (Period 1), as well as mass balance, pharmacokinetics, metabolism, and excretion of [
14 C]-mobocertinib (Period 2) in healthy adult males. In Period 1, participants received a single oral capsule dose of 160 mg mobocertinib, followed by a 15-minute intravenous infusion of 50 µg (~ 2 µCi) [14 C]-mobocertinib administered from 3.75 to 4 h after the capsule dose. In Period 2, a single oral dose of 160 mg (~ 100 µCi) [14 C]-mobocertinib was administered as an oral solution. The geometric mean absolute bioavailability of mobocertinib was determined to be 36.7%. After oral administration of [14 C]-mobocertinib, mobocertinib and its active metabolites, AP32960 and AP32914, were minor components in plasma, accounting for only 0.275% of total plasma radioactivity as the majority of mobocertinib-related material was covalently bound to plasma proteins. The geometric mean percentage of the administered radioactive dose recovered in the urine and feces was 3.57% and 76.0%, respectively. Only 0.39% of the oral dose of [14 C]-mobocertinib was recovered in the urine as mobocertinib; thus, indicating that renal excretion of unchanged drug was a very minor pathway of elimination. In both treatment periods, mobocertinib was generally safe and well-tolerated as all adverse events were Grade 1 in severity. (Trial registration number ClinicalTrials.gov NCT03811834. Registration date January 22, 2019)., (© 2024. The Author(s).)- Published
- 2024
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34. Postpartum Weight Change Association With Readmission and Blood Pressure Trend Among Individuals With Hypertensive Disorders of Pregnancy.
- Author
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Lemon LS, Venkatakrishnan K, Countouris M, Simhan H, and Hauspurg A
- Subjects
- Humans, Female, Pregnancy, Adult, Retrospective Studies, Risk Factors, Weight Gain, Weight Loss, Time Factors, Risk Assessment, Young Adult, Patient Readmission trends, Patient Readmission statistics & numerical data, Hypertension, Pregnancy-Induced physiopathology, Hypertension, Pregnancy-Induced diagnosis, Hypertension, Pregnancy-Induced epidemiology, Postpartum Period, Blood Pressure physiology
- Abstract
Background: The aim of this study was to evaluate the association between early postpartum weight change and (1) hospital readmission and (2) 2-week blood pressure trajectory., Methods and Results: This retrospective study cohort included 1365 individuals with a hypertensive disorder of pregnancy enrolled in a postpartum hypertension remote monitoring program. Exposure was percentage weight change from delivery to first weight recorded within 10 days postpartum. We first modeled likelihood of hospital readmission within 8 weeks postpartum using logistic regression adjusting for age, race, insurance, type of hypertensive disorder of pregnancy, early body mass index, gestational weight gain, mode of delivery, and any discharge antihypertensive medications. We then performed case-control analysis additionally matching in a 1:3 ratio on breastfeeding, early body mass index, discharge on antihypertensive medications, and days between weight measurements. Both analytic approaches were repeated, limiting to readmissions attributable to hypertension or heart failure. Finally, we compared blood pressure trajectories over first 2 weeks postpartum. Individuals who did not lose weight in the early postpartum period had more admissions compared with weight loss groups (group 3: 14.1% versus group 2: 5.8% versus group 1: 4.5%). These individuals had 4 times the odds of postpartum readmissions (adjusted odds ratio [aOR], 3.9 [95% CI, 1.8-8.6]) to 7 (aOR, 7.8 [95% CI, 2.3-26.5]) compared with those with the most weight loss. This association strengthened when limited to hypertension or heart failure readmissions. These individuals also had more adverse postpartum blood pressure trajectories, with significant differences by weight change group., Conclusions: Weight change is readily accessible and may identify individuals at high risk for postpartum readmission following a hypertensive disorder of pregnancy who could benefit from targeted interventions.
- Published
- 2024
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35. Antifouling nanoplatform for controlled attachment of E. coli .
- Author
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Tavangar A, Premnath P, Tan B, and Venkatakrishnan K
- Subjects
- Silicon Dioxide chemistry, Biocompatible Materials chemistry, Biocompatible Materials pharmacology, Materials Testing, Nanostructures chemistry, Anti-Bacterial Agents pharmacology, Anti-Bacterial Agents chemistry, Nanoparticles chemistry, Escherichia coli drug effects, Bacterial Adhesion drug effects, Biofilms drug effects, Biofouling prevention & control, Silicon chemistry, Surface Properties
- Abstract
Biofouling is the most common cause of bacterial contamination in implanted materials/devices resulting in severe inflammation, implant mobilization, and eventual failure. Since bacterial attachment represents the initial step toward biofouling, developing synthetic surfaces that prevent bacterial adhesion is of keen interest in biomaterials research. In this study, we develop antifouling nanoplatforms that effectively impede bacterial adhesion and the consequent biofilm formation. We synthesize the antifouling nanoplatform by introducing silicon (Si)/silica nanoassemblies to the surface through ultrafast ionization of Si substrates. We assess the effectiveness of these nanoplatforms in inhibiting Escherichia coli ( E. coli ) adhesion. The findings reveal a significant reduction in bacterial attachment on the nanoplatform compared to untreated silicon, with bacteria forming smaller colonies. By manipulating physicochemical characteristics such as nanoassembly size/concentration and nanovoid size, we further control bacterial attachment. These findings suggest the potential of our synthesized nanoplatform in developing biomedical implants/devices with improved antifouling properties., (© 2024 IOP Publishing Ltd.)
- Published
- 2024
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36. Moving the Needle for Oncology Dose Optimization: A Call for Action.
- Author
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Venkatakrishnan K, Jayachandran P, Seo SK, van der Graaf PH, Wagner JA, and Gupta N
- Subjects
- Humans, Dose-Response Relationship, Drug, Medical Oncology, Neoplasms drug therapy, Antineoplastic Agents administration & dosage
- Published
- 2024
- Full Text
- View/download PDF
37. Asia-Inclusive Global Development of Enpatoran: Results of an Ethno-Bridging Study, Intrinsic/Extrinsic Factor Assessments and Disease Trajectory Modeling to Inform Design of a Phase II Multiregional Clinical Trial.
- Author
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Klopp-Schulze L, Gopalakrishnan S, Yalkinoglu Ö, Kuroki Y, Lu H, Goteti K, Krebs-Brown A, Nogueira Filho M, Gradhand U, Fluck M, Shaw J, Dong J, and Venkatakrishnan K
- Subjects
- Adult, Female, Humans, Male, Middle Aged, Asia, Lupus Erythematosus, Cutaneous drug therapy, Research Design, Clinical Trials, Phase II as Topic, East Asian People, White, Lupus Erythematosus, Systemic drug therapy, Toll-Like Receptors antagonists & inhibitors
- Abstract
Enpatoran is a novel, highly selective, and potent dual toll-like receptor (TLR)7 and TLR8 inhibitor currently under development for the treatment of autoimmune disorders including systemic lupus erythematosus (SLE), cutaneous lupus erythematosus (CLE), and myositis. The ongoing phase II study (WILLOW; NCT05162586) is evaluating enpatoran for 24 weeks in patients with active SLE or CLE and is currently recruiting. To support development of WILLOW as an Asia-inclusive multiregional clinical trial (MRCT) according to International Conference on Harmonisation E5 and E17 principles, we have evaluated ethnic sensitivity to enpatoran based on clinical pharmacokinetic (PK), pharmacodynamic (PD), and safety data from an ethno-bridging study (NCT04880213), supplemented by relevant quantitative PK, PD, and disease trajectory modeling (DTM) results, and drug metabolism/disease knowledge. A single-center, open-label, sequential dose group study in White and Japanese subjects matched by body weight, height, and sex demonstrated comparable PK and PD properties for enpatoran in Asian vs. non-Asian (White and other) subjects across single 100, 200, and 300 mg orally administered doses. DTM suggested no significant differences in SLE disease trajectory for Asian vs. non-Asian individuals. Aldehyde oxidase (AOX) is considered to be a key contributor to enpatoran metabolism, and a literature review indicated no relevant ethnic differences in AOX function based on in vitro and clinical PK data from marketed drugs metabolized by AOX, supporting the conclusion of low ethnic sensitivity for enpatoran. Taken together, the inclusion of Asian patients in MRCTs including WILLOW was informed based on a Totality of Evidence approach., (© 2024 The Healthcare Business of Merck KGaA. Clinical Pharmacology & Therapeutics published by Wiley Periodicals LLC on behalf of American Society for Clinical Pharmacology and Therapeutics.)
- Published
- 2024
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38. Realizing the promise of Project Optimus: Challenges and emerging opportunities for dose optimization in oncology drug development.
- Author
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Gao W, Liu J, Shtylla B, Venkatakrishnan K, Yin D, Shah M, Nicholas T, and Cao Y
- Subjects
- Humans, United States, Dose-Response Relationship, Drug, Drug Development methods, Antineoplastic Agents administration & dosage, Neoplasms drug therapy, United States Food and Drug Administration
- Abstract
Project Optimus is a US Food and Drug Administration Oncology Center of Excellence initiative aimed at reforming the dose selection and optimization paradigm in oncology drug development. This project seeks to bring together pharmaceutical companies, international regulatory agencies, academic institutions, patient advocates, and other stakeholders. Although there is much promise in this initiative, there are several challenges that need to be addressed, including multidimensionality of the dose optimization problem in oncology, the heterogeneity of cancer and patients, importance of evaluating long-term tolerability beyond dose-limiting toxicities, and the lack of reliable biomarkers for long-term efficacy. Through the lens of Totality of Evidence and with the mindset of model-informed drug development, we offer insights into dose optimization by building a quantitative knowledge base integrating diverse sources of data and leveraging quantitative modeling tools to build evidence for drug dosage considering exposure, disease biology, efficacy, toxicity, and patient factors. We believe that rational dose optimization can be achieved in oncology drug development, improving patient outcomes by maximizing therapeutic benefit while minimizing toxicity., (© 2023 Emd Serono Research and Development Institute, Inc. Pfizer Inc and The Authors. CPT: Pharmacometrics & Systems Pharmacology published by Wiley Periodicals LLC on behalf of American Society for Clinical Pharmacology and Therapeutics. This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA.)
- Published
- 2024
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39. Machine Learning in Modeling Disease Trajectory and Treatment Outcomes: An Emerging Enabler for Model-Informed Precision Medicine.
- Author
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Terranova N and Venkatakrishnan K
- Subjects
- Humans, Precision Medicine, Machine Learning, Algorithms, Biomarkers, Artificial Intelligence, Neoplasms drug therapy
- Abstract
The increasing breadth and depth of resolution in biological and clinical data, including -omics and real-world data, requires advanced analytical techniques like artificial intelligence (AI) and machine learning (ML) to fully appreciate the impact of multi-dimensional population variability in intrinsic and extrinsic factors on disease progression and treatment outcomes. Integration of advanced data analytics in Quantitative Pharmacology is crucial for drug-disease knowledge management, enabling precise, efficient and inclusive drug development and utilization - an application we refer to as model-informed precision medicine. AI/ML enables characterization of the molecular and clinical sources of heterogeneity in disease trajectory, advancing end point qualification and biomarker discovery, and informing patient enrichment for proof-of-concept studies as well as trial designs for efficient evidence generation incorporating digital twins and virtual control arms. Explainable ML methods are valuable in elucidating predictors of efficacy and safety of pharmacological treatments, thereby informing response monitoring and risk mitigation strategies. In oncology, emerging opportunities exist for development of the next generation of disease models via ML-assisted joint longitudinal modeling of high-dimensional biomarker data such as circulating tumor DNA and radiomics profiles as predictors of survival outcomes. Finally, mining real-world data leveraging ML algorithms enables understanding of the impact of exclusion criteria on clinical outcomes, thereby informing rational design of appropriately inclusive clinical trials through data-driven broadening of eligibility criteria. Herein, we provide an overview of the aforementioned contexts of use of ML in drug-disease modeling based on examples across multiple therapeutic areas including neurology, rare diseases, autoimmune diseases, oncology and immuno-oncology., (© 2023 Merck KGaA Darmstadt. Clinical Pharmacology & Therapeutics published by Wiley Periodicals LLC on behalf of American Society for Clinical Pharmacology and Therapeutics.)
- Published
- 2024
- Full Text
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40. Evaluation of the drug-drug interaction potential of brigatinib using a physiologically-based pharmacokinetic modeling approach.
- Author
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Hanley MJ, Yeo KR, Tugnait M, Iwasaki S, Narasimhan N, Zhang P, Venkatakrishnan K, and Gupta N
- Subjects
- Humans, Rifampin pharmacokinetics, Cytochrome P-450 CYP3A Inhibitors pharmacology, Itraconazole pharmacology, Cytochrome P-450 CYP3A metabolism, ATP Binding Cassette Transporter, Subfamily G, Member 2, Neoplasm Proteins metabolism, Cytochrome P-450 CYP3A Inducers pharmacokinetics, Drug Interactions, Membrane Transport Proteins, Receptor Protein-Tyrosine Kinases metabolism, Models, Biological, Carcinoma, Non-Small-Cell Lung, Lung Neoplasms, Organophosphorus Compounds, Pyrimidines
- Abstract
Brigatinib is an oral anaplastic lymphoma kinase (ALK) inhibitor approved for the treatment of ALK-positive metastatic non-small cell lung cancer. In vitro studies indicated that brigatinib is primarily metabolized by CYP2C8 and CYP3A4 and inhibits P-gp, BCRP, OCT1, MATE1, and MATE2K. Clinical drug-drug interaction (DDI) studies with the strong CYP3A inhibitor itraconazole or the strong CYP3A inducer rifampin demonstrated that CYP3A-mediated metabolism was the primary contributor to overall brigatinib clearance in humans. A physiologically-based pharmacokinetic (PBPK) model for brigatinib was developed to predict potential DDIs, including the effect of moderate CYP3A inhibitors or inducers on brigatinib pharmacokinetics (PK) and the effect of brigatinib on the PK of transporter substrates. The developed model was able to predict clinical DDIs with itraconazole (area under the plasma concentration-time curve from time 0 to infinity [AUC
∞ ] ratio [with/without itraconazole]: predicted 1.86; observed 2.01) and rifampin (AUC∞ ratio [with/without rifampin]: predicted 0.16; observed 0.20). Simulations using the developed model predicted that moderate CYP3A inhibitors (e.g., verapamil and diltiazem) may increase brigatinib AUC∞ by ~40%, whereas moderate CYP3A inducers (e.g., efavirenz) may decrease brigatinib AUC∞ by ~50%. Simulations of potential transporter-mediated DDIs predicted that brigatinib may increase systemic exposures (AUC∞ ) of P-gp substrates (e.g., digoxin and dabigatran) by 15%-43% and MATE1 substrates (e.g., metformin) by up to 29%; however, negligible effects were predicted on BCRP-mediated efflux and OCT1-mediated uptake. The PBPK analysis results informed dosing recommendations for patients receiving moderate CYP3A inhibitors (40% brigatinib dose reduction) or inducers (up to 100% increase in brigatinib dose) during treatment, as reflected in the brigatinib prescribing information., (© 2024 Takeda Pharmaceuticals. CPT: Pharmacometrics & Systems Pharmacology published by Wiley Periodicals LLC on behalf of American Society for Clinical Pharmacology and Therapeutics.)- Published
- 2024
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41. Immunogenicity of avelumab in patients with metastatic Merkel cell carcinoma or advanced urothelial carcinoma.
- Author
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Hu P, Dai HI, Bourdage J, Zhou D, Trang K, Kowalski K, Bello C, Hibma J, Khandelwal A, Cowan K, Dong J, Venkatakrishnan K, and Gao W
- Subjects
- Humans, Antibodies, Monoclonal, Humanized adverse effects, Clinical Trials as Topic, Carcinoma, Merkel Cell drug therapy, Carcinoma, Merkel Cell pathology, Carcinoma, Transitional Cell drug therapy, Skin Neoplasms drug therapy, Skin Neoplasms pathology, Urinary Bladder Neoplasms
- Abstract
Like other monoclonal antibodies, immune checkpoint inhibitors may be immunogenic in some patients, potentially affecting pharmacokinetics (PKs) and clinical outcomes. In post hoc analyses, we characterized antidrug antibody (ADA) development with avelumab monotherapy in patients with metastatic Merkel cell carcinoma (mMCC) from the JAVELIN Merkel 200 trial (first-line [1L; N = 116] and second-line or later [≥2L; N = 88] cohorts) or with advanced urothelial carcinoma (aUC) from the JAVELIN Bladder 100 (1L maintenance [N = 350]) and JAVELIN Solid Tumor (≥2L [N = 249]) trials. Treatment-emergent ADAs developed in a numerically higher proportion of patients with aUC (1L maintenance, 19.1%; ≥2L, 18.1%) versus mMCC (1L, 8.2%; ≥2L, 8.9%); incidences within tumor types were similar by line of therapy. In PK analyses, numerically lower avelumab trough concentration and higher baseline clearance were observed in treatment-emergent ADA+ versus ADA- subgroups; however, differences were not clinically relevant. Numerical differences in overall survival, progression-free survival, or objective response rate by ADA status were observed; however, no clinically meaningful trends were identified. Proportions of patients with treatment-emergent adverse events (TEAEs; any grade or grade 3/4), serious TEAEs, TEAEs leading to treatment discontinuation, or infusion-related reactions were similar, with overlapping 80% confidence intervals between ADA subgroups. Efficacy and safety observations were similar in subgroups defined by early development of ADA+ status during treatment. In conclusion, no meaningful differences in PKs, efficacy, and safety were observed between subgroups of avelumab-treated patients with different ADA status. Overall, these data suggest that ADAs are not relevant for treatment decisions with avelumab., (© 2024 The Authors. Clinical and Translational Science published by Wiley Periodicals LLC on behalf of American Society for Clinical Pharmacology and Therapeutics.)
- Published
- 2024
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42. Model-based meta-analysis using latent variable modeling to set benchmarks for new treatments of systemic lupus erythematosus.
- Author
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Goteti K, Garcia R, Gillespie WR, French J, Klopp-Schulze L, Li Y, Mateo CV, Roy S, Guenther O, Benincosa L, and Venkatakrishnan K
- Subjects
- Humans, Latent Class Analysis, Bayes Theorem, Treatment Outcome, Benchmarking, Lupus Erythematosus, Systemic drug therapy
- Abstract
Several investigational agents are under evaluation in systemic lupus erythematosus (SLE) clinical trials but quantitative frameworks to enable comparison of their efficacy to reference benchmark treatments are lacking. To benchmark SLE treatment effects and identify clinically important covariates, we developed a model-based meta-analysis (MBMA) within a latent variable model framework for efficacy end points and SLE composite end point scores (BILAG-based Composite Lupus Assessment and Systemic Lupus Erythematosus Responder Index) using aggregate-level data on approved and investigational therapeutics. SLE trials were searched using PubMed and www.clinicaltrials.gov for treatment name, SLE and clinical trial as search criteria that resulted in four data structures: (1) study and investigational agent, (2) dose and regimen, (3) baseline descriptors, and (4) outcomes. The final dataset consisted of 25 studies and 81 treatment arms evaluating 16 different agents. A previously developed (K Goteti et al. 2022) SLE latent variable model of data from placebo arms (placebo + standard of care treatments) was used to describe aggregate SLE end points over time for the various SLE placebo and treatment arms in a Bayesian MBMA framework. Continuous dose-effect relationships using a maximum effect model were included for anifrolumab, belimumab, CC-220 (iberdomide), epratuzumab, lulizumab pegol, and sifalimumab, whereas the remaining treatments were modeled as discrete dose effects. The final MBMA model was then used to benchmark these compounds with respect to the maximal efficacy on the latent variable compared to the placebo. This MBMA illustrates the application of latent variable models in understanding the trajectories of composite end points in chronic diseases and should enable model-informed development of new investigational agents in SLE., (© 2023 EMD Serono Inc. CPT: Pharmacometrics & Systems Pharmacology published by Wiley Periodicals LLC on behalf of American Society for Clinical Pharmacology and Therapeutics.)
- Published
- 2024
- Full Text
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43. Tumor growth inhibition modeling in patients with second line biliary tract cancer and first line non-small cell lung cancer based on bintrafusp alfa trials.
- Author
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Milenković-Grišić AM, Terranova N, Mould DR, Vugmeyster Y, Mrowiec T, Machl A, Girard P, Venkatakrishnan K, and Khandelwal A
- Subjects
- Humans, Carcinoma, Non-Small-Cell Lung drug therapy, Carcinoma, Non-Small-Cell Lung pathology, Lung Neoplasms drug therapy, Lung Neoplasms pathology, Biliary Tract Neoplasms drug therapy
- Abstract
This analysis aimed to quantify tumor dynamics in patients receiving either bintrafusp alfa (BA) or pembrolizumab, by population pharmacokinetic (PK)-pharmacodynamic modeling, and investigate clinical and molecular covariates describing the variability in tumor dynamics by pharmacometric and machine-learning (ML) approaches. Data originated from two clinical trials in patients with biliary tract cancer (BTC; NCT03833661) receiving BA and non-small cell lung cancer (NSCLC; NCT03631706) receiving BA or pembrolizumab. Individual drug exposure was estimated from previously developed population PK models. Population tumor dynamics models were developed for each drug-indication combination, and covariate evaluations performed using nonlinear mixed-effects modeling (NLME) and ML (elastic net and random forest models) approaches. The three tumor dynamics' model structures all included linear tumor growth components and exponential tumor shrinkage. The final BTC model included the effect of drug exposure (area under the curve) and several covariates (demographics, disease-related, and genetic mutations). Drug exposure was not significant in either of the NSCLC models, which included two, disease-related, covariates in the BA arm, and none in the pembrolizumab arm. The covariates identified by univariable NLME and ML highly overlapped in BTC but showed less agreement in NSCLC analyses. Hyperprogression could be identified by higher tumor growth and lower tumor kill rates and could not be related to BA exposure. Tumor size over time was quantitatively characterized in two tumor types and under two treatments. Factors potentially related to tumor dynamics were assessed using NLME and ML approaches; however, their net impact on tumor size was considered as not clinically relevant., (© 2023 Merck KGaA and The Authors. CPT: Pharmacometrics & Systems Pharmacology published by Wiley Periodicals LLC on behalf of American Society for Clinical Pharmacology and Therapeutics.)
- Published
- 2024
- Full Text
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44. Inclusion of Obese Participants in Drug Development: Reflections on the Current Landscape and a Call for Action.
- Author
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Shen J, Moore KT, Shukla S, Yeo KR, and Venkatakrishnan K
- Subjects
- Humans, Obesity, Drug Development, Patient Selection
- Published
- 2024
- Full Text
- View/download PDF
45. Detection of lung cancer metastasis from blood using L-MISC nanosensor: Targeting circulating metastatic cues for improved diagnosis.
- Author
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Premachandran S, Dhinakaran AK, Das S, Venkatakrishnan K, Tan B, and Sharma M
- Subjects
- Humans, Cues, Neoplasm Metastasis diagnosis, Lung Neoplasms diagnosis, Lung Neoplasms pathology, Biosensing Techniques
- Abstract
Metastatic lung cancers are considered one of the most clinically significant malignancies, comprising about 40% of deaths caused by cancers. Detection of lung cancer metastasis prior to symptomatic relapse is critical for timely diagnosis and clinical management. The onset of cancer metastasis is indicated by the manifestation of tumor-shed signatures from the primary tumor in peripheral circulation. A subset of this population, characterized as the metastasis-initiating stem cells, are capable of invasion, tumor initiation, and propagation of metastasis at distant sites. In this study, we have developed a SERS-functionalised L-MISC (Lung-Metastasis Initiating Stem Cells) nanosensor to accurately capture the trace levels of metastatic signatures directly from patient blood. We investigated the signatures of cancer stem cell enriched heterogenous population of primary and metastatic lung cancer cells to establish a metastatic profile unique to lung cancer. Multivariate statistical analyses revealed statistically significant differences in the molecular profiles of healthy, primary, and metastatic cell populations. The single-cell sensitivity of L-MISC nanosensor enabled a label-free detection of MISCs with high sensitivity and specificity. By employing a robust machine learning model, our diagnostic methodology can accurately detect metastatic lung cancer from not more than 5 μl of blood. A pilot validation of our study was carried out using clinical samples for the prediction of metastatic lung cancers resulting in 100% diagnostic sensitivity. The L-MISC nanosensor is a potential tool for highly rapid, non-invasive, and accurate diagnosis of lung cancer metastasis., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)
- Published
- 2024
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- View/download PDF
46. Dexamethasone-Free Antiemetic Prophylaxis for Highly Emetogenic Chemotherapy: A Double-Blind, Phase III Randomized Controlled Trial (CINV POD study).
- Author
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Radhakrishnan V, Venkatakrishnan K, Perumal Kalaiyarasi J, Selvarajan G, Mahaboobasha N, Victor PV, Anbazhagan M, Sivanandam DM, and Rajaraman S
- Subjects
- Humans, Adolescent, Young Adult, Adult, Middle Aged, Aged, Aged, 80 and over, Palonosetron adverse effects, Olanzapine adverse effects, Vomiting chemically induced, Vomiting prevention & control, Vomiting drug therapy, Nausea chemically induced, Nausea prevention & control, Nausea drug therapy, Antiemetics therapeutic use
- Abstract
Purpose: The effectiveness of a dexamethasone (DEX)-free regimen for chemotherapy-induced nausea and vomiting (CINV) prophylaxis in patients receiving highly emetogenic chemotherapy (HEC) is not known., Methods: This was a double-blind, phase III trial designed to show the noninferiority of a DEX-free regimen (olanzapine, palonosetron, and fosaprepitant [OPF]) compared with the DEX-containing regimen (olanzapine, palonosetron, and DEX [OPD]). Chemotherapy-naïve patients age 18-80 years receiving single-day HEC were randomly assigned 1:1 to receive either the OPD regimen or the OPF regimen. The primary objective was to compare complete response (CR) rates for vomiting during the overall period (start of chemotherapy to 120 hours). Secondary objectives included CR for vomiting during the acute period (0-24 hours) and delayed period (24-120 hours), CR for nausea, and comparison of toxicities and patient-reported outcomes., Results: Three hundred forty-six patients received the study interventions, 174 in the OPD arm and 172 in the OPF arm. The DEX-free OPF arm had significantly higher CR rates for vomiting compared with the DEX-containing OPD arm in acute (94.7% v 85.6%; P < .004), delayed (81.9% v 50.5%; P < .001), and overall (79.6% v 48.8%; P < .001) periods. For nausea, CR rates in the OPF arm were higher in delayed (53.4% v 39.6%; P = .009) and overall (50.5% v 39.1%; P = .031) periods but not in the acute period (77.9% v 81.6%; P = .39). Fatigue ( P = .009) and drowsiness ( P = .002) were more in the OPF arm in the acute period and insomnia ( P < .001) in the OPD arm in the overall period., Conclusion: This study shows that a DEX-free OPF regimen is efficacious and should be considered a standard option for acute and delayed CINV prophylaxis for HEC.
- Published
- 2024
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47. Model-Informed Selection of the Recommended Phase III Dose of the Inhibitor of Apoptosis Protein Inhibitor, Xevinapant, in Combination with Cisplatin and Concurrent Radiotherapy in Patients with Locally Advanced Squamous Cell Carcinoma of the Head and Neck.
- Author
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Vugmeyster Y, Ravula A, Rouits E, Diderichsen PM, Kleijn HJ, Koenig A, Wang X, Schroeder A, Goteti K, and Venkatakrishnan K
- Subjects
- Humans, Cisplatin adverse effects, Squamous Cell Carcinoma of Head and Neck chemically induced, Squamous Cell Carcinoma of Head and Neck drug therapy, Leukocytes, Mononuclear pathology, Chemoradiotherapy adverse effects, Chemoradiotherapy methods, Antineoplastic Combined Chemotherapy Protocols therapeutic use, Head and Neck Neoplasms drug therapy, Head and Neck Neoplasms chemically induced, Antineoplastic Agents adverse effects, Carcinoma, Squamous Cell drug therapy, Carcinoma, Squamous Cell pathology
- Abstract
Xevinapant, an oral inhibitor of apoptosis protein (IAP) inhibitor, demonstrated efficacy in combination with chemoradiotherapy in a randomized phase II study (NCT02022098) in patients with locally advanced squamous cell carcinoma of the head and neck at 200 mg/day on days 1-14 of a 3-week cycle. To confirm 200 mg/day as the recommended phase III dose (RP3D), we integrated preclinical, clinical, pharmacokinetic/pharmacodynamic (PK/PD), and exposure-response modeling results. Population PK/PD modeling of IAP inhibition in peripheral blood mononuclear cells in 21 patients suggested the pharmacologically active dose range was 100-200 mg/day, with a trend for more robust inhibition at the end of the dosing interval at 200 mg/day based on an indirect response model. Additionally, the unbound average plasma concentration at 200 mg/day was similar to that associated with efficacy in preclinical xenograft models. Logistic regression exposure-response analyses of data from 62 patients in the phase II study showed exposure-related increases in probabilities of locoregional control at 18 months (primary end point), overall response, complete response, and the radiosensitization mechanism-related composite safety end point "mucositis and/or dysphagia" (P < 0.05). Exposure-response relationships were not discernible for 12 of 13 evaluated safety end points, incidence of dose reductions, and time to first dose reduction. Quantitative integration of all available data, including model-derived target inhibition profiles, positive exposure-efficacy relationships, and lack of discernible exposure-safety relationships for most safety end points, supports selection of xevinapant 200 mg/day on days 1-14 of a 3-week cycle as the RP3D, allowing for successive dose reductions to 150 and 100 mg/day to manage adverse events., (© 2023 EMD Serono and The Authors. Clinical Pharmacology & Therapeutics published by Wiley Periodicals LLC on behalf of American Society for Clinical Pharmacology and Therapeutics.)
- Published
- 2024
- Full Text
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48. Challenges and Opportunities for In Vitro-In Vivo Extrapolation of Aldehyde Oxidase-Mediated Clearance: Toward a Roadmap for Quantitative Translation.
- Author
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Izat N, Bolleddula J, Abbasi A, Cheruzel L, Jones RS, Moss D, Ortega-Muro F, Parmentier Y, Peterkin VC, Tian DD, Venkatakrishnan K, Zientek MA, Barber J, Houston JB, Galetin A, and Scotcher D
- Subjects
- Humans, Metabolic Clearance Rate, Hepatocytes metabolism, Microsomes, Liver metabolism, Aldehyde Oxidase metabolism, Liver metabolism
- Abstract
Underestimation of aldehyde oxidase (AO)-mediated clearance by current in vitro assays leads to uncertainty in human dose projections, thereby reducing the likelihood of success in drug development. In the present study we first evaluated the current drug development practices for AO substrates. Next, the overall predictive performance of in vitro-in vivo extrapolation of unbound hepatic intrinsic clearance (CL
int,u ) and unbound hepatic intrinsic clearance by AO (CLint,u,AO ) was assessed using a comprehensive literature database of in vitro (human cytosol/S9/hepatocytes) and in vivo (intravenous/oral) data collated for 22 AO substrates (total of 100 datapoints from multiple studies). Correction for unbound fraction in the incubation was done by experimental data or in silico predictions. The fraction metabolized by AO (fmAO ) determined via in vitro/in vivo approaches was found to be highly variable. The geometric mean fold errors (gmfe) for scaled CLint,u (mL/min/kg) were 10.4 for human hepatocytes, 5.6 for human liver cytosols, and 5.0 for human liver S9, respectively. Application of these gmfe's as empirical scaling factors improved predictions (45%-57% within twofold of observed) compared with no correction (11%-27% within twofold), with the scaling factors qualified by leave-one-out cross-validation. A road map for quantitative translation was then proposed following a critical evaluation on the in vitro and clinical methodology to estimate in vivo fmAO In conclusion, the study provides the most robust system-specific empirical scaling factors to date as a pragmatic approach for the prediction of in vivo CLint,u,AO in the early stages of drug development. SIGNIFICANCE STATEMENT: Confidence remains low when predicting in vivo clearance of AO substrates using in vitro systems, leading to de-prioritization of AO substrates from the drug development pipeline to mitigate risk of unexpected and costly in vivo impact. The current study establishes a set of empirical scaling factors as a pragmatic tool to improve predictability of in vivo AO clearance. Developing clinical pharmacology strategies for AO substrates by utilizing mass balance/clinical drug-drug interaction data will help build confidence in fmAO ., (Copyright © 2023 by The Author(s).)- Published
- 2023
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- View/download PDF
49. A multistate modeling and simulation framework to learn dose-response of oncology drugs: Application to bintrafusp alfa in non-small cell lung cancer.
- Author
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Liu H, Milenković-Grišić AM, Krishnan SM, Jönsson S, Friberg LE, Girard P, Venkatakrishnan K, Vugmeyster Y, Khandelwal A, and Karlsson MO
- Subjects
- Humans, Progression-Free Survival, Computer Simulation, Probability, B7-H1 Antigen therapeutic use, Carcinoma, Non-Small-Cell Lung, Lung Neoplasms pathology
- Abstract
The dose/exposure-efficacy analyses are often conducted separately for oncology end points like best overall response, progression-free survival (PFS) and overall survival (OS). Multistate models offer to bridge these dose-end point relationships by describing transitions and transition times from enrollment to response, progression, and death, and evaluating transition-specific dose effects. This study aims to apply the multistate pharmacometric modeling and simulation framework in a dose optimization setting of bintrafusp alfa, a fusion protein targeting TGF-β and PD-L1. A multistate model with six states (stable disease [SD], response, progression, unknown, dropout, and death) was developed to describe the totality of endpoints data (time to response, PFS, and OS) of 80 patients with non-small cell lung cancer receiving 500 or 1200 mg of bintrafusp alfa. Besides dose, evaluated predictor of transitions include time, demographics, premedication, disease factors, individual clearance derived from a pharmacokinetic model, and tumor dynamic metrics observed or derived from tumor size model. We found that probabilities of progression and death upon progression decreased over time since enrollment. Patients with metastasis at baseline had a higher probability to progress than patients without metastasis had. Despite dose failed to be statistically significant for any individual transition, the combined effect quantified through a model with dose-specific transition estimates was still informative. Simulations predicted a 69.2% probability of at least 1 month longer, and, 55.6% probability of at least 2-months longer median OS from the 1200 mg compared to the 500 mg dose, supporting the selection of 1200 mg for future studies., (© 2023 The Authors. CPT: Pharmacometrics & Systems Pharmacology published by Wiley Periodicals LLC on behalf of American Society for Clinical Pharmacology and Therapeutics.)
- Published
- 2023
- Full Text
- View/download PDF
50. Self-Functionalized Superlattice Nanosensor Enables Glioblastoma Diagnosis Using Liquid Biopsy.
- Author
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Premachandran S, Haldavnekar R, Ganesh S, Das S, Venkatakrishnan K, and Tan B
- Subjects
- Humans, Liquid Biopsy, Biomarkers, Tumor, Glioblastoma diagnosis, Glioblastoma pathology, Brain Neoplasms diagnosis, Brain Neoplasms pathology, Extracellular Vesicles pathology
- Abstract
Glioblastoma (GBM), the most aggressive and lethal brain cancer, is detected only in the advanced stage, resulting in a median survival rate of 15 months. Therefore, there is an urgent need to establish GBM diagnosis tools to identify the tumor accurately. The clinical relevance of the current liquid biopsy techniques for GBM diagnosis remains mostly undetermined, owing to the challenges posed by the blood-brain barrier (BBB) that restricts biomarkers entering the circulation, resulting in the unavailability of clinically validated circulating GBM markers. GBM-specific liquid biopsy for diagnosis and prognosis of GBM has not yet been developed. Here, we introduce extracellular vesicles of GBM cancer stem cells (GBM CSC-EVs) as a previously unattempted, stand-alone GBM diagnosis modality. As GBM CSCs are fundamental building blocks of tumor initiation and recurrence, it is desirable to investigate these reliable signals of malignancy in circulation for accurate GBM diagnosis. So far, there are no clinically validated circulating biomarkers available for GBM. Therefore, a marker-free approach was essential since conventional liquid biopsy relying on isolation methodology was not viable. Additionally, a mechanism capable of trace-level detection was crucial to detecting the rare GBM CSC-EVs from the complex environment in circulation. To break these barriers, we applied an ultrasensitive superlattice sensor, self-functionalized for surface-enhanced Raman scattering (SERS), to obtain holistic molecular profiling of GBM CSC-EVs with a marker-free approach. The superlattice sensor exhibited substantial SERS enhancement and ultralow limit of detection (LOD of attomolar 10
-18 M concentration) essential for trace-level detection of invisible GBM CSC-EVs directly from patient serum (without isolation). We detected as low as 5 EVs in 5 μL of solution, achieving the lowest LOD compared to existing SERS-based studies. We have experimentally demonstrated the crucial role of the signals of GBM CSC-EVs in the precise detection of glioblastoma. This was evident from the unique molecular profiles of GBM CSC-EVs demonstrating significant variation compared to noncancer EVs and EVs of GBM cancer cells, thus adding more clarity to the current understanding of GBM CSC-EVs. Preliminary validation of our approach was undertaken with a small amount of peripheral blood (5 μL) derived from GBM patients with 100% sensitivity and 97% specificity. Identification of the signals of GBM CSC-EV in clinical sera specimens demonstrated that our technology could be used for accurate GBM detection. Our technology has the potential to improve GBM liquid biopsy, including real-time surveillance of GBM evolution in patients upon clinical validation. This demonstration of liquid biopsy with GBM CSC-EV provides an opportunity to introduce a paradigm potentially impacting the current landscape of GBM diagnosis.- Published
- 2023
- Full Text
- View/download PDF
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