Efficacy and Safety of Abrilumab in a Randomized, Placebo-Controlled Trial for Moderate-to-Severe Ulcerative Colitis.

BACKGROUND & AIMS: The α4ß7 integrin is a validated target in inflammatory bowel disease. This randomized, phase 2b, placebo-controlled, double-blind study evaluated the efficacy and safety of the anti-α4ß7 antibody abrilumab in patients with moderate-to-severe ulcerative colitis despite treatment with conventional therapies. METHODS: Patients (total Mayo Score 6-12, recto-sigmoidoscopy score ≥2) with inadequate response or intolerance to conventional therapies were randomized to receive subcutaneous abrilumab (7, 21, or 70 mg) on day 1, weeks 2 and 4, and every 4 weeks; abrilumab 210 mg on day 1; or placebo. The primary end point was remission (total Mayo Score ≤2 points, no individual sub-score >1 point) for the 2 highest dosages at week 8. Key secondary end points were response and mucosal healing (centrally read) at week 8. RESULTS: For 354 patients who received ≥1 dose of investigational product (placebo, n = 116; 7 mg, n = 21; 21 mg, n = 40; 70 mg, n = 98; 210 mg, n = 79), non-adjusted remission rates at week 8 were 4.3%, 13.3%, and 12.7% for the placebo and abrilumab 70-mg and 210-mg groups, respectively (P < .05 for 70 and 210 mg vs placebo); odds of achieving remission were significantly greater with abrilumab 70 mg (odds ratio 3.35; 90% CI 1.41-7.95; P = .021) and 210 mg (odds ratio 3.33; 90% confidence interval 1.34-8.26; P = .030) than with placebo. Response and mucosal healing rates with these dosages also were significantly greater than with placebo. Higher baseline α4ß7 levels on naïve CD4+ T cells were a prognostic indicator for overall outcome, but not a predictive biomarker of abrilumab response. There were no cases of progressive multifocal leukoencephalopathy or deaths. CONCLUSIONS: Abrilumab treatment for 8 weeks induced remission, clinical response, and mucosal healing in patients with moderate-to-severe ulcerative colitis. ClinicalTrials.gov, number NCT01694485.

Evaluation of near infrared fluorescent labeling of monoclonal antibodies as a tool for tissue distribution.

The pharmacokinetic (PK) behavior of monoclonal antibodies (mAbs) is influenced by target-mediated drug disposition, off-target effects, antidrug antibody-mediated clearance, and interaction with fragment-crystallizable domain (Fc) receptors such as neonatal Fc receptor. All of these interactions hold the potential to impact mAb biodistribution. Near infrared (NIR) fluorescent probes offer an approach complementary to radionuclides to characterize drug disposition. Notably, the use of FDA-approved IRDye800 (IR800; LI-COR, Lincoln, NE) as a protein-labeling agent in preclinical work holds the potential for quantitative tissue analysis. Here, we tested the utility of the IR800 dye as a quantitative mAb tracer during pharmacokinetic analysis in both plasma and tissues using a model mouse monoclonal IgG1 (8C2) labeled with ≤1.5 molecules of IR800. The plasma PK parameters derived from a mixture of IR800-8C2 and 8C2 dosed intravenously to C57BL/6 mice at 8 mg/kg exhibited a large discrepancy in exposure depending on the method of quantitation [CLplasma = 8.4 ml/d per kilogram (NIR fluorescence detection) versus 2.5 ml/d per kilogram (enzyme-linked immunosorbent assay)]. The disagreement between measurements suggests that the PK of 8C2 is altered by addition of the IR800 dye. Additionally, direct fluorescence analysis of homogenized tissues revealed several large differences in IR800-8C2 tissue uptake when compared with a previously published study using [(125)I]8C2, most notably an over 4-fold increase in liver concentration. Finally, the utility of IR800 in combination with whole body imaging was examined by comparison of IR800-8C2 levels observed in animal sagittal cross-sections to those measured in homogenized tissues. Our results represent the first PK analysis in both mouse plasma and tissues of an IR800-mAb conjugate and suggest that mAb disposition is significantly altered by IR800 conjugation to 8C2.

Population Pharmacokinetic Modeling and Exposure-Efficacy and Body Weight-Response Analyses for Tezepelumab in Patients With Severe, Uncontrolled Asthma.

Tezepelumab is a human monoclonal antibody that blocks the activity of thymic stromal lymphopoietin. This analysis assessed the suitability of a fixed-dose regimen of tezepelumab 210 mg every 4 weeks (Q4W) in adults and adolescents with severe, uncontrolled asthma. A population pharmacokinetic model was developed using data from 1368 patients with asthma or healthy participants enrolled in 8 clinical studies (phases 1-3). Tezepelumab exposure-efficacy relationships were analyzed in the phase 3 NAVIGATOR study (NCT03347279), using asthma exacerbation rates over 52 weeks and changes in pre-bronchodilator forced expiratory volume in 1 s at week 52. Tezepelumab pharmacokinetics were well characterized by a 2-compartment linear disposition model with first-order absorption and elimination following subcutaneous and intravenous administration at 2.1-420 and 210-700 mg, respectively. There were no clinically relevant effects on tezepelumab pharmacokinetics from age (≥12 years), sex, race/ethnicity, renal or hepatic function, disease severity (inhaled corticosteroid dose level), concomitant asthma medication use, smoking history, or anti-drug antibodies. Body weight was the most influential covariate on tezepelumab exposure, but no meaningful differences in efficacy or safety were observed across body weight quartiles in patients with asthma who received tezepelumab 210 mg subcutaneously Q4W. There was no apparent relationship between tezepelumab exposure and efficacy at this dose regimen, suggesting that it is on the plateau of the exposure-response curve of tezepelumab. In conclusion, a fixed-dose regimen of tezepelumab 210 mg subcutaneously Q4W is appropriate for eligible adults and adolescents with severe, uncontrolled asthma.

Investigation of the role of FcγR and FcRn in mAb distribution to the brain.

To evaluate the role of Fc receptors (FcR) on IgG distribution to the brain, the disposition of 8C2, a murine monoclonal IgG1 antibody, was investigated after intravenous administration in FcRn α-chain knockout mice, FcγRIIb knockout mice, FcγRI/RIII knockout mice, and C57BL/6 control mice. (125)I-8C2 was co-administered with (51)Cr-labeled red blood cells to allow accurate assessment of residual blood content in brain samples. Blood and brain tissues were harvested from subgroups of three mice at several time-points up to 10 days, and radioactivity was counted. The blood and brain areas under 8C2 concentration vs time curves (AUCs) were calculated using the linear trapezoidal rule, and the associated standard deviations (SD) were assessed using a modified Bailer method. Concentration data were also analyzed with a semiphysiological population pharmacokinetic model. The brain/blood AUC ratios were comparable across all strains of mice (ratios ± SD): 0.00774 ± 0.000452, 0.00841 ± 0.000535, 0.00636 ± 0.000548, and 0.00917 ± 0.000478 for C57BL/6 control mice, FcγRI/RIII knockouts, FcγRIIb knockouts, and FcRn α-chain knockout mice (p > 0.05). Statistically significant improvement in model fitting of the data was shown with incorporation of a strain-specific parameter for antibody clearance for FcRn knockout mice; however, no significant improvements in model fitting were found for strain effects on any other parameter, including the brain uptake clearance or efflux clearances for 8C2. The predicted 8C2 brain efflux clearance was found to be ∼135-fold faster than the brain uptake clearance, consistent with the observed low ratio of brain-blood exposure. The experimental results and modeling results indicate that, in mice, FcRn and FcγR do not contribute to the "blood-brain barrier" that limits mAb uptake into the brain.

Pharmacokinetics and Pharmacokinetic/Pharmacodynamic Properties of Rozibafusp Alfa, a Bispecific Inhibitor of BAFF and ICOSL: Analyses of Phase I Clinical Trials.

Rozibafusp alfa (AMG 570) is a first-in-class bispecific IgG2-peptide fusion designed to inhibit inducible T-cell costimulator ligand (ICOSL) and B-cell activating factor (BAFF). The pharmacokinetics (PK) and pharmacodynamics (PD) of rozibafusp alfa were investigated in two randomized, placebo-controlled clinical studies: a phase Ia single ascending-dose study (7-700 mg subcutaneously (s.c.)) in healthy subjects and a phase Ib multiple ascending-dose study (70-420 mg s.c. every 2 weeks (q2w)) in patients with rheumatoid arthritis. Rozibafusp alfa exhibited nonlinear PK and dose-related and reversible dual-target engagement. Maximal reduction of naïve B cells from baseline (> 40%), reflective of BAFF inhibition, was achieved with rozibafusp alfa exposure (area under the concentration-time curve from time 0 to time infinity (AUCinf ) and AUC within a dosing interval from day 0 to day 14 (AUCtau )) above 51 and 57 days•µg/mL for the single-dose (≥ 70 mg) and multiple-dose studies (≥ 70 mg q2w), respectively. ICOSL receptor occupancy on circulating B cells, a surrogate PD end point for ICOSL inhibition, was directly related to drug concentration. PK/PD analysis showed > 90% RO at rozibafusp alfa ≥ 22.2 µg/mL (≥ 420-mg single dose or ≥ 210 mg q2w multiple dose), with saturation occurring at higher drug concentrations. These results informed the design and dose selection of a phase IIb study assessing the safety and efficacy of rozibafusp alfa in patients with active systemic lupus erythematosus.

High-throughput method development for sensitive, accurate, and reproducible quantification of therapeutic monoclonal antibodies in tissues using orthogonal array optimization and nano liquid chromatography/selected reaction monitoring mass spectrometry.

Although liquid chromatography/mass spectrometry using selected reaction monitoring (LC/SRM-MS) holds great promise for targeted protein analysis, quantification of therapeutic monoclonal antibody (mAb) in tissues represents a daunting challenge due to the extremely low tissue levels, complexity of tissue matrixes, and the absence of an efficient strategy to develop an optimal LC/SRM-MS method. Here we describe a high-throughput, streamlined strategy for the development of sensitive, selective, and reliable quantitative methods of mAb in tissue matrixes. A sensitive nano-LC/nanospray-MS method was employed to achieve a low lower limit of quantification (LOQ). For selection of signature peptides (SP), the SP candidates were identified by a high-resolution Orbitrap and then optimal SRM conditions for each candidate were obtained using a high-throughput, on-the-fly orthogonal array optimization (OAO) strategy, which is capable of optimizing a large set of SP candidates within a single nano-LC/SRM-MS run. Using the optimized conditions, the candidates were experimentally evaluated for both sensitivity and stability in the target matrixes, and SP selection was based on the results of the evaluation. Two unique SP, respectively from the light and heavy chain, were chosen for quantification of each mAb. The use of two SP improves the quantitative reliability by gauging possible degradation/modification of the mAb. Standard mAb proteins with verified purities were utilized for calibration curves, to prevent the quantitative biases that may otherwise occur when synthesized peptides were used as calibrators. We showed a proof of concept by rapidly developing sensitive nano-LC/SRM-MS methods for quantifying two mAb (8c2 and cT84.66) in multiple preclinical tissues. High sensitivity was achieved for both mAb with LOQ ranged from 0.156 to 0.312 µg/g across different tissues, and the overall procedure showed a wide dynamic range (≥500-fold) and good accuracy [relative error (RE) < 18.8%] and precision [interbatch relative standard deviation (RSD) < 18.1%, intrabatch RSD < 17.2%]. The quantitative method was applied to a comprehensive investigation of the steady-state tissue distribution of 8c2 in wild-type mice versus those deficient in FcRn α-chain, FcγIIb, and FcγRI/FcγRIII, following a chronic dosing regimen. This work represents the first extensive quantification of mAb in tissues by an LC/MS-based method.

Application of PBPK modeling to predict monoclonal antibody disposition in plasma and tissues in mouse models of human colorectal cancer.

This investigation evaluated the utility of a physiologically based pharmacokinetic (PBPK) model, which incorporates model parameters representing key determinants of monoclonal antibody (mAb) target-mediated disposition, to predict, a priori, mAb disposition in plasma and in tissues, including tumors that express target antigens. Monte Carlo simulation techniques were employed to predict the disposition of two mAbs, 8C2 (as a non-binding control mouse IgG1 mAb) and T84.66 (a high-affinity murine IgG1 anti-carcinoembryonic antigen mAb), in mice bearing no tumors, or bearing colorectal HT29 or LS174T xenografts. Model parameters were obtained or derived from the literature. (125)I-T84.66 and (125)I-8C2 were administered to groups of SCID mice, and plasma and tissue concentrations were determined via gamma counting. The PBPK model well-predicted the experimental data. Comparisons of the population predicted versus observed areas under the plasma concentration versus time curve (AUC) for T84.66 were 95.4 ± 67.8 versus 84.0 ± 3.0, 1,859 ± 682 versus 2,370 ± 154, and 5,930 ± 1,375 versus 5,960 ± 317 (nM × day) at 1, 10, and 25 mg/kg in LS174T xenograft-bearing SCID mice; and 215 ± 72 versus 233 ± 30, 3,070 ± 346 versus 3,120 ± 180, and 7,884 ± 714 versus 7,440 ± 626 in HT29 xenograft-bearing mice. Model predicted versus observed 8C2 plasma AUCs were 312.4 ± 30 versus 182 ± 7.6 and 7,619 ± 738 versus 7,840 ± 24.3 (nM × day) at 1 and 25 mg/kg. High correlations were observed between the predicted median plasma concentrations and observed median plasma concentrations (r (2) = 0.927, for all combinations of treatment, dose, and tumor model), highlighting the utility of the PBPK model for the a priori prediction of in vivo data.

Development and Evaluation of Competitive Inhibitors of Trastuzumab-HER2 Binding to Bypass the Binding-Site Barrier.

Our group has developed and experimentally validated a strategy to increase antibody penetration in solid tumors through transient inhibition of antibody-antigen binding. In prior work, we demonstrated that 1HE, an anti-trastuzumab single domain antibody that transiently inhibits trastuzumab binding to HER2, increased the penetration of trastuzumab and increased the efficacy of ado-trastuzumab emtansine (T-DM1) in HER2+ xenograft bearing mice. In the present work, 1HE variants were developed using random mutagenesis and phage display to enable optimization of tumor penetration and efficacy of trastuzumab-based therapeutics. To guide the rational selection of a particular 1HE mutant for a specific trastuzumab-therapy, we developed a mechanistic pharmacokinetic (PK) model to predict within-tumor exposure of trastuzumab/T-DM1. A pharmacodynamic (PD) component was added to the model to predict the relationship between intratumor exposure to T-DM1 and the corresponding therapeutic effect in HER2+ xenografts. To demonstrate the utility of the competitive inhibition approach for immunotoxins, PK parameters specific for a recombinant immunotoxin were incorporated into the model structure. Dissociation half-lives for variants ranged from 1.1 h (for variant LG11) to 107.9 h (for variant HE10). Simulations predicted that 1HE co-administration can increase the tumor penetration of T-DM1, with inhibitors with longer trastuzumab binding half-lives relative to 1HE (15.5 h) further increasing T-DM1 penetration at the expense of total tumor uptake of T-DM1. The PK/PD model accurately predicted the response of NCI-N87 xenografts to treatment with T-DM1 or T-DM1 co-administered with 1HE. Model predictions indicate that the 1HE mutant HF9, with a trastuzumab binding half-life of 51.1 h, would be the optimal inhibitor for increasing T-DM1 efficacy with a modest extension in the median survival time relative to T-DM1 with 1HE. Model simulations predict that LG11 co-administration will dramatically increase immunotoxin penetration within all tumor regions. We expect that the mechanistic model structure and the wide range of inhibitors developed in this work will enable optimization of trastuzumab-cytotoxin penetration and efficacy in solid tumors.

Safety and Biological Activity of Rozibafusp alfa, a Bispecific Inhibitor of Inducible Costimulator Ligand and B Cell Activating Factor, in Patients With Rheumatoid Arthritis: Results of a Phase 1b, Randomized, Double-Blind, Placebo-Controlled, Multiple Ascending Dose Study.

OBJECTIVE: To assess the safety and biological activity of rozibafusp alfa, a first-in-class bispecific antibody-peptide conjugate targeting inducible costimulator ligand (ICOSL) and B cell activating factor (BAFF), in patients with rheumatoid arthritis (RA). METHODS: This phase 1b, double-blind, placebo-controlled, multiple ascending dose study included 34 patients (18-75 years; 82.4% female) with active RA (Disease Activity Score of 28 joints-C-reactive protein [DAS28-CRP] >2.6, on stable methotrexate) randomized 3:1 to receive rozibafusp alfa (n = 26, in four ascending dose cohorts of 70, 140, 210, and 420 mg) or a placebo (n = 8) subcutaneously once every 2 weeks for 10 weeks (six total doses), with 24 weeks of follow-up. The primary end point was the incidence of treatment-emergent adverse events (TEAEs). Additional assessments included serum pharmacokinetics (PK), pharmacodynamics (PD), immunogenicity, and RA disease activity measures (DAS28-CRP, Patient Global Assessment of Disease, and Physician Global Assessment of Disease). RESULTS: TEAEs occurred in 96.2% and 87.5% of patients receiving rozibafusp alfa and the placebo, respectively; most were mild or moderate in severity. Two (7.7%) patients treated with rozibafusp alfa reported serious TEAEs; none were considered treatment related. Multiple doses of rozibafusp alfa showed nonlinear PK (mean t1/2  = 4.6-9.5 days) and dose-related, reversible PD (>90% ICOSL receptor occupancy in 210- and 420-mg cohorts; reduction in naïve B cells and increase in memory B cells in all cohorts). Five (20%) patients developed anti-rozibafusp alfa antibodies, with no apparent impact on safety. RA disease activity showed greater numerical improvement from baseline with rozibafusp alfa versus the placebo in the 210- and 420-mg cohorts. CONCLUSION: Multiple ascending doses of rozibafusp alfa were well tolerated, with PK and PD reflecting dual ICOSL and BAFF blockade. Findings support further clinical evaluation of rozibafusp alfa in autoimmune disease.

Tezepelumab Pharmacokinetics, Safety, and Tolerability After Administration via Vial-and-syringe, Accessorized Prefilled Syringe, or Autoinjector: A Randomized Trial in Healthy Volunteers.

PURPOSE: Tezepelumab is an anti-thymic stromal lymphopoietin monoclonal antibody therapeutic in development for patients with severe, uncontrolled asthma. In ongoing Phase III studies, tezepelumab is administered via subcutaneous (SC) injections using a vial-and-syringe (V-S). This study compared the pharmacokinetic (PK) parameters, safety, and tolerability of tezepelumab administered subcutaneously via V-S versus via an accessorized prefilled syringe (APFS) or autoinjector (AI). METHODS: This single-center, randomized, open-label, parallel-group study was conducted in healthy volunteers aged 18-65 years. Participants, stratified according to weight (50 to <70 kg, 70 to <80 kg, or 80-90 kg), were randomized evenly to 9 groups representing injections to the abdomen, thigh, or upper arm via V-S, APFS, or AI. Tezepelumab PK parameters over 113 days were evaluated after a single 210-mg SC dose. The primary end points were comparison of Cmax and AUC0-∞ between device groups. Further PK parameters, immunogenicity, safety (including injection site reactions [ISRs] and injection site pain [visual analog scale]) were also assessed. FINDINGS: A total of 315 adults were randomized to treatment. Geometric mean ratios for comparisons between device groups of Cmax, AUC0-∞, and AUC0-last were close to 1, with 90% CIs all within the range of 0.8-1.25, meeting bioequivalence criteria. PK variables were also similar between devices across injection sites and weight categories. Across devices, thigh injection resulted in slightly higher exposure than upper arm injection, and abdomen injection resulted in exposure similar to or slightly lower than thigh injection; however, these differences were not clinically meaningful. Treatment-emergent anti-tezepelumab antibodies were present in 3 (2.9%), 1 (1.0%), and 0 participants in the V-S, APFS, and AI groups, respectively. Treatment-related adverse events were reported in 15.0% of participants overall (V-S, 10.7%; APFS, 18.1%; AI, 16.0%), including ISRs in 1 (1.0%), 3 (2.9%), and 3 (2.8%) participants in the V-S, APFS, and AI groups. Median visual analog scale pain score (0-100 mm scale) was 2 mm immediately after injection and was 0 mm at 30 min for all groups. IMPLICATIONS: Tezepelumab PK parameters after a single 210-mg SC dose were comparable when administered via V-S, APFS, or AI. In all groups, immunogenicity rate and injection site pain were low, and ISRs were uncommon. These findings support administration of tezepelumab via APFS or AI, in addition to V-S, providing patients and physicians with greater choice and the potential convenience of at-home use. ClinicalTrials.gov identifier: NCT03989544.

AKR-001, an Fc-FGF21 Analog, Showed Sustained Pharmacodynamic Effects on Insulin Sensitivity and Lipid Metabolism in Type 2 Diabetes Patients.

Experimental fibroblast growth factor 21 (FGF21) analogs can improve lipid profiles in patients with metabolic diseases. However, their effects on markers of insulin sensitivity appear to be minimal, potentially because of insufficient exposure. Systemic drug levels vary from sub-pharmacological to demonstrating pharmacodynamic effects but with dose-limiting adverse events. Here we report results from a phase 1 multiple ascending dose study of AKR-001, an Fc-FGF21 fusion protein engineered for sustained systemic pharmacologic exposure, in individuals with type 2 diabetes. With a half-life of 3-3.5 days, the peak-to-trough ratio under steady-state conditions is approximately 2 following QW dosing. AKR-001 appears to demonstrate pharmacodynamic effects on serum markers of insulin sensitivity and acceptable tolerability up to and including 70 mg QW. Positive trends in lipoprotein profile, including triglycerides, non-high-density lipoprotein (non-HDL) cholesterol, HDL-C, and apolipoproteins B and C3 are consistent with other FGF21 analogs. AKR-001's clinical profile supports further evaluation as a treatment for metabolic diseases.

Assessments of antibody biodistribution.

Monoclonal antibody (mAb) therapeutics are in use for several disease conditions, and have generally shown excellent clinical benefit, in large part due to their high specificity and affinity for target proteins. As this therapeutic class continues to grow in size, improved understanding of the mechanisms controlling mAb biodistribution and protein binding may be expected to allow better prediction of safety and efficacy. Due to the large size and polarity of antibodies, rates of mAb distribution and elimination are typically much slower than those reported for small molecule drugs. Additionally, high affinity interaction with target proteins will often influence mAb pharmacokinetics, leading to complex, nonlinear tissue distribution and elimination. In this report, we summarize key determinants of mAb disposition, methods for assessing antibody exposure and protein binding, and model-based approaches that may be utilized to predict mAb pharmacokinetics.

Antibody engineering and therapeutics, The Annual Meeting of the Antibody Society: December 8-12, 2013, Huntington Beach, CA.

The 24th Antibody Engineering & Therapeutics meeting brought together a broad range of participants who were updated on the latest advances in antibody research and development. Organized by IBC Life Sciences, the gathering is the annual meeting of The Antibody Society, which serves as the scientific sponsor. Preconference workshops on 3D modeling and delineation of clonal lineages were featured, and the conference included sessions on a wide variety of topics relevant to researchers, including systems biology; antibody deep sequencing and repertoires; the effects of antibody gene variation and usage on antibody response; directed evolution; knowledge-based design; antibodies in a complex environment; polyreactive antibodies and polyspecificity; the interface between antibody therapy and cellular immunity in cancer; antibodies in cardiometabolic medicine; antibody pharmacokinetics, distribution and off-target toxicity; optimizing antibody formats for immunotherapy; polyclonals, oligoclonals and bispecifics; antibody discovery platforms; and antibody-drug conjugates.

Application of knockout mouse models to investigate the influence of FcγR on the pharmacokinetics and anti-platelet effects of MWReg30, a monoclonal anti-GPIIb antibody.

This work evaluates the influence of FcγR on the pharmacokinetics and pharmacodynamics of a rat anti-integrin-αIIb IgG1 monoclonal antibody, MWReg30, in mice. The pharmacokinetics and pharmacodynamics of MWReg30 were investigated in C57BL/6 control mice, FcγRI/RIII knockout mice, and FcγRIIb knockout mice, following intravenous doses of 0.04-0.4mg/kg. MWReg30 treatment resulted in a dose-dependent induction of thrombocytopenia in all strains, but sensitivity to MWReg30 was increased in FcγRIIb knockout mice and decreased in FcγRI/RIII knockout mice, relative to results found in control mice. Expressed as a percentage of pre-treatment platelet counts, nadir platelet counts were 28.6±5.0, 88.7±16.6 and 25.3±6.1% at 0.05mg/kg, 28.4±13.7, 56.7±5.1, and 20.6±9.5% at 0.2mg/kg, and 24.9±7.2, 38.7±7.5, and 7.4±2.2% at 0.4mg/kg in control, FcγRI/RIII(-/-) and FcγRIIb(-/-) mice. However, knocking out FcγR did not affect MWReg30 pharmacokinetics. Plasma areas under the concentration vs. time curves (AUC0-10 days) ±SD for MWReg30 were: 5.24±0.68, 5.51±0.24, and 5.39±1.05 nM×d at 0.04mg/kg, and 12.7±0.5, 13.6±1.1, and 14.5±2.0nM×d at 0.1mg/kg in control, FcγRI/RIII(-/-) and FcγRIIb(-/-) mice. The findings further emphasize the role of activating vs. inhibitory FcγR in processing immune complexes (i.e., MWReg30-platelets), while also providing an example where monoclonal antibody pharmacokinetics are not substantially influenced by FcγR expression.

Application of knockout mouse models to investigate the influence of FcγR on the tissue distribution and elimination of 8C2, a murine IgG1 monoclonal antibody.

The current work examines the role of Fcγ-receptors on the elimination and tissue distribution of 8C2, a model murine IgG1 monoclonal antibody. The plasma pharmacokinetics of (125)Iodine-labeled 8C2 were investigated in C57BL/6 control mice, FcγRI/RIII knockout mice, and FcγRIIb knockout mice, following intravenous doses of 0.04, 0.1 and 0.4 mg/kg. Plasma samples were collected and radioactivity was counted. Concentration data were analyzed with a population pharmacokinetic model. Additionally, the tissue disposition of 8C2 was investigated using whole body autoradioluminography (WBAL) and via counting excised tissues. Areas under the plasma concentration vs. time curves AUC(0-10 days) ±SD (nM×days) were: 12.3±0.3, 12.5±1.3 and 15.1±1.2 at 0.04 mg/kg; 39.3±2.0, 28.9±2.7 and 42.0±9.4 at 0.1 mg/kg; and 225±19, 158±19 and 204±26 at 0.4 mg/kg in C57BL/6, FcγRI/RIII(-/-) and FcγRIIb(-/-) mice. Strain was not a statistically significant predictor for any of the parameters of the population model. 8C2 plasma clearance, distribution clearance, and central compartment volume were 0.00543 L/days/kg, 0.0598 L/days/kg, and 0.057 L/kg. No substantial differences in 8C2 tissue uptake were identified by analysis of excised tissues or by WBAL. In conclusion, FcγR knockout is associated with only minor effects on the plasma and tissue disposition of 8C2, a model murine IgG1 mAb.

Pharmacokinetic mAb-mAb interaction: anti-VEGF mAb decreases the distribution of anti-CEA mAb into colorectal tumor xenografts.

To date, there has been little investigation of the risk for drug-drug interactions involving monoclonal antibodies. The present work examined the effects of an anti-vascular endothelial growth factor (anti-VEGF) antibody on the plasma, tissue, and tumor disposition of T84.66, an anti-carcinoembryonic antigen (CEA) antibody, in mice. SCID mice bearing CEA-expressing human colorectal cancer (LS174T) xenografts were divided into control and anti-VEGF-treated groups. When tumors reached 200-300 mm(3) in size, (125)I-T84.66 was administered intravenously at 10 mg/kg (400 µCi/kg). Radioactivity in plasma and tissue samples was counted, and T84.66 concentrations were determined. Areas under the concentration vs. time curves (AUC) were calculated. In separate groups of mice, Evans Blue Dye was administered to evaluate the effect of anti-VEGF on tumor vascular permeability. The investigations did not demonstrate significant effects of anti-VEGF therapy on T84.66 pharmacokinetics in plasma or in non-tumor tissues. T84.66 plasma AUC((0-10 days)) values were 2.37 × 10(3) ± 1.54 × 10(2) and 2.56 × 10(3) ± 1.01 × 10(2) nM × day, for the control and treated groups (p = 0.148). Conversely, anti-VEGF treatment significantly reduced tumor vascular permeability to Evans Blue Dye by 45.0 % (p = 0.0012), and anti-VEGF therapy decreased T84.66 tumor AUC((0-10 days)) by more than 60 % (7.27 × 10(2) ± 51.4 vs. 1.98 × 10(3) ± 90.1 nM × day, p < 0.0001). Our findings suggest that anti-VEGF therapies may lead to a substantial reduction in the delivery of monoclonal antibodies to tumor tissues. It is interesting and important to note that this pharmacokinetic interaction occurs at the target site, and that no alterations in T84.66 disposition were visible based on assessment of plasma pharmacokinetics alone.