Subcutaneous Administration of Monoclonal Antibodies: Pharmacology, Delivery, Immunogenicity, and Learnings From Applications to Clinical Development.

Subcutaneous (s.c.) administration of monoclonal antibodies (mAbs) can reduce treatment burden for patients and healthcare systems compared with intravenous (i.v.) infusion through shorter administration times, made possible by convenient, patient-centric devices. A deeper understanding of clinical pharmacology principles related to efficacy and safety of s.c.-administered mAbs over the past decade has streamlined s.c. product development. This review presents learnings from key constituents of the s.c. mAb development pathway, including pharmacology, administration variables, immunogenicity, and delivery devices. Restricted mAb transportation through the hypodermis explains their incomplete absorption at a relatively slow rate (pharmacokinetic (PK)) and may impact mAb-cellular interactions and/or onset and magnitude of physiological responses (pharmacodynamic). Injection volumes, formulation, rate and site of injection, and needle attributes may affect PKs and the occurrence/severity of adverse events like injection-site reactions or pain, with important consequences for treatment adherence. A review of immunogenicity data for numerous compounds reveals that incidence of anti-drug antibodies (ADAs) is generally comparable across i.v. and s.c. routes, and complementary factors including response magnitude (ADA titer), persistence over time, and neutralizing antibody presence are needed to assess clinical impact. Finally, four case studies showcase how s.c. biologics have been clinically developed: (i) by implementation of i.v./s.c. bridging strategies to streamline PD-1/PD-L1 inhibitor development, (ii) through co-development with i.v. presentations for anti-severe acute respiratory syndrome-coronavirus 2 antibodies to support rapid deployment of both formulations, (iii) as the lead route for bispecific T cell engagers (BTCEs) to mitigate BTCE-mediated cytokine release syndrome, and (iv) for pediatric patients in the case of dupilumab.

Population pharmacokinetic and exposure-response analysis for trastuzumab administered using a subcutaneous "manual syringe" injection or intravenously in women with HER2-positive early breast cancer.

PURPOSE: To characterize the population pharmacokinetics (PKs) of subcutaneous (SC) and intravenous (IV) trastuzumab in early breast cancer (EBC), assess the impact of covariates on trastuzumab PK, and evaluate fixed (nonweight-based) dosing for the SC regimen administrated via handheld syringe. METHODS: Serum trastuzumab concentrations from 595 patients with HER2-positive EBC in the HannaH study (fixed 600 mg SC trastuzumab or weight-based IV trastuzumab) were analyzed using nonlinear mixed-effects modeling. Multiple logistic regression was used to assess the exposure-response relationships between PK, efficacy [pathologic complete response (pCR)], and safety [grade ≥3 adverse events (AEs)]. RESULTS: Trastuzumab PK was described by a two-compartment model with parallel linear and nonlinear elimination and first-order SC absorption, with a bioavailability of 77 %. Estimated total clearance (CL) values were 0.18-0.22 L/day for steady-state trough/peak concentrations of 75-148 µg/mL; the estimate for central volume of distribution was 2.9 L. Body weight and alanine transaminase, while showing significant effects on PK, only explained 8% of the variability in CL. Exposure-response analyses showed no relationship between PK, pCR, and grade ≥3 AEs for either regimen. CONCLUSION: A fixed 600 mg SC dose of trastuzumab provides the desired exposure, with steady-state trough concentrations (35-123 µg/mL for the 5th-95th percentiles) above the historical target concentration of 20 µg/mL for efficacy. Fixed dosing is further supported by lack of an exposure-response relationship between PK, pCR, and grade ≥3 AEs. No dose adjustment per patient factors is required within the ranges studied.

Population pharmacokinetic and covariate analysis of pertuzumab, a HER2-targeted monoclonal antibody, and evaluation of a fixed, non-weight-based dose in patients with a variety of solid tumors.

PURPOSE: To characterize the population pharmacokinetics (PK) of pertuzumab across clinical trials in a variety of solid tumors, evaluate the potential impact of patient characteristics on PK, and confirm the appropriateness of the fixed (non-weight-based) dose. METHODS: Pertuzumab concentration data collected following intravenous administration during eleven phase I/II studies and the pivotal phase III trial CLEOPATRA were analyzed using nonlinear mixed-effects modeling. The potential impact of patient and laboratory characteristics and HER2 target-related variables on pertuzumab PK were investigated in a covariate analysis. The final model was used to confirm selection of fixed, non-weight-based dosing of pertuzumab, and to compare pertuzumab PK in CLEOPATRA with the other studies. RESULTS: The analysis included 4,525 serum concentration measurements from 481 patients with solid tumors. Pertuzumab PK in the 2-25 mg/kg dose range was described by a two-compartment linear model with first-order elimination. The elimination clearance and central compartment volume were 0.235 L/day, and 3.11 L, respectively, and the terminal elimination half-life was 18.0 days. Baseline serum albumin and lean body weight had statistically significant effects on pertuzumab clearance; however, simulations showed that the magnitude of their effects on pertuzumab exposure was minimal compared with overall variability and was not clinically relevant. Thus, variations in these factors do not require dose adjustments. CONCLUSIONS: The fixed, non-weight-based dosing of pertuzumab, 840 mg loading dose followed by a 420 mg maintenance dose every 3 weeks, in patients with the solid tumors in this analysis is well supported by the population pharmacokinetic modeling and simulation results.

Pharmacokinetics of ranibizumab after intravitreal administration in patients with retinal vein occlusion or diabetic macular edema.

OBJECTIVE: To describe the systemic pharmacokinetics of ranibizumab after intravitreal administration in patients with retinal vein occlusion (RVO) or diabetic macular edema (DME). DESIGN: A population approach of nonlinear mixed-effect pharmacokinetics modeling based on serum concentrations of ranibizumab measured at various times after intravitreal administration. PARTICIPANTS: Patients with RVO (n = 441) and DME (n = 435) from 4 large, randomized, phase 3 clinical trials of monthly ranibizumab intravitreal administration. METHODS: A 1-compartment pharmacokinetics model with first-order absorption and elimination rate constants previously developed in patients with age-related macular degeneration (AMD) was fitted separately to RVO and DME data. Population pharmacokinetic parameters and interindividual variability were estimated for each model. Baseline covariates were evaluated for potential effects on systemic pharmacokinetics. Model performance was validated using general diagnostic plots and a visual predictive check. MAIN OUTCOME MEASURES: Ranibizumab disposition was determined in RVO and DME patients and compared with that previously seen in AMD patients. RESULTS: The AMD pharmacokinetics model correctly predicted the measured serum ranibizumab concentration data for RVO and DME patients. Most observed data points were within the simulated 90% confidence interval, indicating that systemic ranibizumab concentrations were comparable among AMD, RVO, and DME patients. No disease-related covariates were identified by the population pharmacokinetics analysis. CONCLUSIONS: The systemic pharmacokinetics of ranibizumab were similar among patients with AMD, RVO, or DME. Disease-related differences and patient demographics, measured in this study, did not lead to variability in ocular elimination or in systemic exposure of ranibizumab after intravitreal administration. In all disease processes tested, ranibizumab exits the eye slowly and then is eliminated rapidly from the circulation, thus minimizing systemic exposure.

Systemic pharmacokinetics following intravitreal injections of ranibizumab, bevacizumab or aflibercept in patients with neovascular AMD.

BACKGROUND: Data comparing systemic exposure and systemic vascular endothelial growth factor (VEGF) suppression of ranibizumab, bevacizumab and aflibercept following intravitreal injection are lacking. METHODS: Fifty-six patients with wet age-related macular degeneration received intravitreal ranibizumab (0.5 mg), bevacizumab (1.25 mg), or aflibercept (2.0 mg). Serum pharmacokinetics and plasma free VEGF were evaluated after the first and third injections. RESULTS: Following the first dose, systemic exposure to aflibercept was 5-, 37-, and 9-fold higher than ranibizumab, whereas, bevacizumab was 9-, 310-, and 35-fold higher than ranibizumab, based on geometric mean ratio of peak and trough concentrations and area under the curve, respectively. The third dose showed accumulation of bevacizumab and aflibercept but not ranibizumab. Aflibercept substantially suppressed plasma free VEGF, with mean levels below lower limit of quantitation (10 pg/mL) as early as 3 h postdose until ≥7 days postdose. Mean free (unbound) VEGF levels with ranibizumab were largely unchanged, with mean trough level of 14.4 pg/mL compared with baseline of 17 pg/mL. CONCLUSIONS: There are notable differences in systemic pharmacokinetics and pharmacodynamics among anti-VEGF treatments after intravitreal administration. All three agents rapidly moved into the bloodstream, but ranibizumab very quickly cleared, whereas bevacizumab and aflibercept demonstrated greater systemic exposure and produced a marked reduction in plasma free VEGF. TRIAL REGISTRATION NUMBER: NCT02118831.

Exposure-response analysis of pertuzumab in HER2-positive metastatic breast cancer: absence of effect on QTc prolongation and other ECG parameters.

PURPOSE: The phase III trial of pertuzumab plus trastuzumab plus docetaxel versus placebo plus trastuzumab plus docetaxel for first-line treatment of HER2-positive metastatic breast cancer included a substudy to determine whether pertuzumab affected the corrected QT (QTc) interval or other electrocardiogram parameters. METHODS: Triplicate 12-lead electrocardiogram measurements and serum samples were collected before (-30 and -15 min) and after (0-15 and 60-75 min) pertuzumab/placebo infusions (Cycles 1 and 3), and at 72 h post-infusion (Cycle 1). Fridericia's correction was applied to QT measurements (QTcF) and change from baseline (ΔQTcF) calculated. Statistical analyses were performed on baseline-adjusted, placebo-corrected QTcF values (ΔΔQTcF). Linear mixed-effects modeling evaluated potential exposure-response relationships between ΔQTcF and observed pertuzumab concentrations. RESULTS: Thirty-seven female patients participated in the substudy. QTcF values in both groups were within the normal range and below critical thresholds of clinical concern. No pertuzumab-treated patient showed abnormal electrocardiogram morphology. In Cycle 1, mean ΔΔQTcF (90 % CI) values at 0-15 min, 60-75 min, and 72 h post-infusion were -6.96 (-13.69, -0.23), -6.35 (-13.57, 0.88), and -4.08 (-12.64, 4.48), all of which were <5 ms, with upper CI limits <10 ms. One Cycle 3 post-infusion mean ΔΔQTcF value exceeded 5 ms. Other electrocardiogram parameters were within normal ranges. Concentration-QTc modeling showed no apparent relationship between ΔQTcF and pertuzumab concentrations. CONCLUSIONS: Cardiac monitoring and concentration-QTc modeling demonstrated that pertuzumab, combined with trastuzumab and docetaxel, had no clinically relevant effects on QTcF and other electrocardiogram parameters.

Absence of pharmacokinetic drug-drug interaction of pertuzumab with trastuzumab and docetaxel.

Pertuzumab is a novel antihuman epidermal growth factor receptor 2 (HER2) humanized monoclonal antibody. Combined with trastuzumab plus docetaxel, pertuzumab improved progression-free and overall survival versus trastuzumab plus docetaxel in the phase III CLEOPATRA trial (NCT00567190) in first-line HER2-positive metastatic breast cancer. Thirty-seven patients participated in a pharmacokinetic (PK)/corrected QT interval substudy of CLEOPATRA, which evaluated potential PK drug-drug interaction (DDI). PK parameters were calculated using noncompartmental methods, and DDI analyses were carried out. In the presence of trastuzumab and docetaxel, the mean pertuzumab Cmin and Cmax in cycle 3 were 63.6 and 183 µg/ml, respectively. The pertuzumab concentrations observed were consistent with simulations from a validated population PK model, indicating that trastuzumab and docetaxel did not alter pertuzumab PK. Comparison of geometric least-squares mean PK parameters between arms showed no impact of pertuzumab on the PK of trastuzumab or docetaxel. In conclusion, no PK DDI was observed when pertuzumab, trastuzumab, and docetaxel were combined for the treatment of HER2-positive metastatic breast cancer.

Population-based efficacy modeling of omalizumab in patients with severe allergic asthma inadequately controlled with standard therapy.

Omalizumab, a recombinant humanized monoclonal antibody, is the first approved anti-immunoglobulin E (IgE) agent for the treatment of subjects with moderate to severe persistent allergic asthma that are inadequately controlled by the standard of care. The objective of this study was to quantitatively characterize relationships between serum free IgE and pulmonary function (as measured by forced expiratory volume in 1 s [FEV1]) as well as serum free IgE and airway inflammation (as measured by fractional exhaled nitric oxide [FeNO]) using population-based efficacy models. Data were collected from patients in the EXTRA trial who received omalizumab or placebo 150 to 375 mg subcutaneously every 2 or 4 weeks from week 0 to 48 with constant standard of care as background therapy. None of the covariates evaluated, including demographics, disease status, and baseline pharmacodynamic biomarkers, were significant in explaining the variability in the FEV1 or FeNO response to omalizumab. Results from the efficacy models further confirmed the current omalizumab dosing rationale based on the mean target free IgE level of 25 ng/ml and quantified the variability for the target. In addition, the resulting population models could be used to predict population FEV1 or FeNO response for omalizumab and/or other anti-IgE therapeutics for which PK-IgE models are constructed.

A randomised phase I study of etrolizumab (rhuMAb ß7) in moderate to severe ulcerative colitis.

OBJECTIVE: Etrolizumab (rhuMAb ß7, anti-ß7, PRO145223) is a humanised monoclonal antibody targeting the ß7 subunit of the heterodimeric integrins α4ß7 and αEß7, which are implicated in leucocyte migration and retention in ulcerative colitis (UC). This randomised phase I study evaluated the safety and pharmacology of etrolizumab in patients with moderate to severe UC. DESIGN: In the single ascending dose (SAD) stage, etrolizumab (0.3, 1.0, 3.0, 10 mg/kg intravenous, 3.0 mg/kg subcutaneous (SC) or placebo) was administered 4:1 (n=25) in each cohort. In the multiple dose (MD) stage, new patients received monthly etrolizumab (0.5 mg/kg SC (n=4), 1.5 mg/kg SC (n=5), 3.0 mg/kg SC (n=4), 4.0 mg/kg intravenous (n=5)) or placebo (n=5). The pharmacokinetics was studied and Mayo Clinic Score evaluated at baseline, day 29 (SAD), and days 43 and 71 (MD). RESULTS: In the SAD stage, there were no dose limiting toxicities, infusion or injection site reactions. Two impaired wound healing serious adverse events occurred in two patients receiving etrolizumab. In the MD stage, there were no dose limiting toxicities, and no infusion or injection site reactions. Headache was the most common adverse event, occurring more often in etrolizumab patients. Antietrolizumab antibodies were detected in two subjects. The duration of ß7 receptor full occupancy was dose related. A clinical response was observed in 12/18 patients, and clinical remission in 3/18 patients treated with etrolizumab in the MD stage, compared with 4/5 and 1/5 placebo patients, respectively. CONCLUSION: Etrolizumab is well tolerated in moderate to severe UC. Further investigation is warranted.

Characterization of the long-term pharmacokinetics of bevacizumab following last dose in patients with resected stage II and III carcinoma of the colon.

PURPOSE: The study characterizes the long-term pharmacokinetics (PK) following last dose of bevacizumab as adjuvant therapy in patients with resected stage II and III colon carcinoma in a Phase III clinical study (AVF3077s). METHODS: Patients in AVF3077s received bevacizumab (5 mg/kg every 2 weeks) as adjuvant therapy for 1 year. Following the last dose bevacizumab concentration, data at 3 and 6 months were used to characterize long-term bevacizumab PK based on the population-modeling approach. RESULTS: The long-term bevacizumab PK were consistent with previously reported results based on short-term bevacizumab PK. The clearance (CL), central volume of distribution (V(1)), intercompartmental clearance (Q), and the peripheral volume of distribution (V(2)) were 214 mL/day, 2,830 mL, 636 mL/day, and 2,490 mL, which correspond to a disposition and elimination half-life of 1.33 and 19.1 days, respectively. The empirical Bayes estimates of median post-treatment bevacizumab drug levels at 3 and 6 months were 6.14 and 0.23 µg/mL, respectively. For test covariates, the change in CL and V(1) of bevacizumab was less than 20% of the typical value. Body weight is the important covariate explaining the inter-individual variability on CL and V(1). CONCLUSIONS: Long-term bevacizumab PK in this study was predictable based on short-term PK data from metastatic settings in other tumor types. An exploratory analysis demonstrated no apparent association of the tested covariates with bevacizumab PK. Further, the extended serum persistence of bevacizumab following last dose should be considered in clinical study designs and post-treatment evaluations that may be affected by bevacizumab.

Pharmacokinetics and pharmacodynamics of anti-BR3 monoclonal antibody in mice.

PURPOSE: To characterize the pharmacokinetic (PK) and pharmacodynamic (PD) properties of a monoclonal antibody directed against the B-cell activating factor (BAFF) receptor 3 (BR3), following intravenous (IV) and subcutaneous (SC) administration in mice. METHODS: Single IV doses of 0.2, 2.0 and 20 mg/kg and a single SC injection of 20 mg/kg of anti-BR3 antibody was administered to mice. Serum drug and BAFF concentrations and splenic B-cell concentrations were measured at various time points. Pooled PK profiles were described by a two-compartmental model with time-dependent nonlinear elimination, and BAFF profiles were defined by an indirect response model. Fractional receptor occupancy served as the driving function for a competitive reversible antagonism model to characterize B-cell dynamics. RESULTS: Noncompartmental analysis revealed a decrease in drug clearance (31.3 to 7.93 mL/day/kg) with increasing IV doses. The SC dose exhibited slow absorption (T(max) = 2 days) and complete bioavailability. All doses resulted in a dose-dependent increase in BAFF concentrations and decrease in B-cell counts. The proposed model reasonably captured complex PK/PD profiles of anti-BR3 antibody after IV and SC administration. CONCLUSIONS: A mechanistic model was developed that describes the reversible competition between anti-BR3 antibody and BAFF for BR3 receptors and its influence on B-cell pharmacodynamics.

Minipig as a potential translatable model for monoclonal antibody pharmacokinetics after intravenous and subcutaneous administration.

Subcutaneous (SC) delivery is a common route of administration for therapeutic monoclonal antibodies (mAbs) with pharmacokinetic (PK)/pharmacodynamic (PD) properties requiring long-term or frequent drug administration. An ideal in vivo preclinical model for predicting human PK following SC administration may be one in which the skin and overall physiological characteristics are similar to that of humans. In this study, the PK properties of a series of therapeutic mAbs following intravenous (IV) and SC administration in Göttingen minipigs were compared with data obtained previously from humans. The present studies demonstrated: (1) minipig is predictive of human linear clearance; (2) the SC bioavailabilities in minipigs are weakly correlated with those in human; (3) minipig mAb SC absorption rates are generally higher than those in human and (4) the SC bioavailability appears to correlate with systemic clearance in minipigs. Given the important role of the neonatal Fc-receptor (FcRn) in the PK of mAbs, the in vitro binding affinities of these IgGs against porcine, human and cynomolgus monkey FcRn were tested. The result showed comparable FcRn binding affinities across species. Further, mAbs with higher isoelectric point tended to have faster systemic clearance and lower SC bioavailability in both minipig and human. Taken together, these data lend increased support for the use of the minipig as an alternative predictive model for human IV and SC PK of mAbs.

Population pharmacokinetics of rituximab in patients with chronic lymphocytic leukemia.

This retrospective analysis characterizes rituximab population pharmacokinetics in combination with fludarabine and cyclophosphamide and its effect on fludarabine and cyclophosphamide disposition in chronic lymphocytic leukemia (CLL) patients. Rituximab concentration data were well described by a 2-compartment model comprising a time-varying clearance component related to the target-mediated clearance pathway and a constant clearance component reflecting catabolic elimination pathway. Marked differences were observed compared to pharmacokinetic parameters for non-Hodgkin lymphoma (NHL) obtained previously: in CLL, time-varying clearance at time zero (CL(2)) was faster, volumes of distribution (V(1) and V(2)) were larger, and rate of change (K(des)) from the targetmediated clearance pathway to catabolic elimination was lower than NHL. Fludarabine and cyclophosphamide disposition showed no apparent change when co-administered with rituximab. A positive correlation between pharmacokinetic parameters and clinical response was observed, supporting the use of the higher rituximab dose of 500 mg/m(2) in CLL patients (vs 375 mg/m(2) in NHL) to achieve an effective clinical response.

Use of quantitative pharmacology in the development of HAE1, a high-affinity anti-IgE monoclonal antibody.

HAE1, a high-affinity anti-IgE monoclonal antibody, is discussed here as a case study in the use of quantitative pharmacology in the development of a second-generation molecule. In vitro, preclinical, and clinical data from the first-generation molecule, omalizumab, were heavily leveraged in the HAE1 program. A preliminary mechanism-based pharmacokinetic/pharmacodynamic (PK/PD) model for HAE1 was developed using an existing model for omalizumab, together with in vitro binding data for HAE1 and omalizumab. When phase I data were available, the model was refined by simultaneously modeling PK/PD data from omalizumab studies with the available HAE1 phase I data. The HAE1 clinical program was based on knowledge of the quantitative relationship between a pharmacodynamic biomarker, suppression of free IgE, and clinical response (e.g., lower exacerbation rates) obtained in pivotal studies with omalizumab. A clinical trial simulation platform was developed to predict free IgE levels and clinical responses following attainment of a target free IgE level (

Nonclinical safety, pharmacokinetics, and pharmacodynamics of atacicept.

Atacicept, a soluble recombinant fusion protein of the human immunoglobulin (Ig) G(1) Fc and the extracellular domain of the human transmembrane activator and calcium modulator and cyclophylin ligand interactor receptor, acts as an antagonist of both B lymphocyte stimulator and a proliferating-inducing ligand. Here we determined the nonclinical safety, pharmacokinetics and pharmacodynamics of atacicept in mice and cynomolgus monkeys. Subcutaneous atacicept treatment (twice weekly in cynomolgus monkeys, three times weekly in mice) was generally safe and well tolerated safe and well tolerated with dosing up to 10 mg/kg every other day for up to 39 weeks or up to 80 mg/kg when dosed for 4 weeks. At a dose of 1 mg/kg subcutaneous (sc) bioavailability of atacicept in mice and monkeys was 76 and 92%, with a mean serum t(1/2) of 44 and 179 h, respectively. In accord with its anticipated mechanism of action, repeated administration of atacicept decreased serum IgG concentrations up to 50%, IgM concentrations >99%, and circulating mature B-cell concentrations up to 60%. These effects were dose-related but reversible, as determined in a 25-week follow-up period. Microscopically, B cells numbers were reduced in the follicular marginal zone of the spleen and the mantle surrounding germinal centers of the lymph nodes. These data confirm the preclinical safety and the pharmacological activity of atacicept and support its clinical development.

Pharmacokinetics and biological activity of atacicept in patients with rheumatoid arthritis.

Atacicept is a recombinant fusion protein containing the extracellular ligand-binding portion of the transmembrane activator and CAML interactor (TACI, CD267) receptor and inhibits B lymphocyte stimulator (BLyS, CD257) and a proliferation-inducing ligand (APRIL, CD256), both potent stimulators of B cell maturation, proliferation, and survival. Atacicept pharmacokinetics and pharmacodynamics were assessed in a double-blind, placebo-controlled, phase I study in patients with active, moderate to severe rheumatoid arthritis receiving atacicept either as a single subcutaneous or repeated, every other week dose. Pharmacokinetic profiles were determined by measuring serum concentrations of free atacicept and its complex with BLyS. Nonspecific immunoglobulin (Ig)M, IgG, and IgA; IgM-RF (rheumatoid factor), IgG-RF, and IgA-RF antibody levels; and B cell profiles provided markers of biological activity. Pharmacokinetic, biological activity, and relationships between atacicept dose and Ig antibody response were evaluated. Pharmacokinetic profiles of atacicept were nonlinear, influenced by saturable binding with its ligands, but were consistent and predictable. Atacicept treatment reduced Ig and RF serum concentration. IgM antibody levels were most sensitive to atacicept, followed by IgA and IgG, underlining the biological activity of atacicept in patients with rheumatoid arthritis. These findings can be used to explore dosing regimen design scenarios in future studies.

Targeting immune complex-mediated hypersensitivity with recombinant soluble human FcgammaRIA (CD64A).

Binding of Ag-Ab immune complexes to cellular FcgammaR promotes cell activation, release of inflammatory mediators, and tissue destruction characteristic of autoimmune disease. To evaluate whether a soluble FcgammaR could block the proinflammatory effects of immune complexes, recombinant human (rh) versions of FcgammaRIA, FcgammaRIIA, and FcgammaRIIIA were prepared. Binding of rh-FcgammaRIA to IgG was of high affinity (KD=1.7x10(-10) M), whereas rh-FcgammaRIIA and rh-FcgammaRIIIA bound with low affinity (KD=0.6-1.9x10(-6) M). All rh-FcgammaR reduced immune complex precipitation, blocked complement-mediated lysis of Ab-sensitized RBC, and inhibited immune complex-mediated production of IL-6, IL-13, MCP-1, and TNF-alpha by cultured mast cells. Local or systemic delivery only of rh-FcgammaRIA, however, reduced edema and neutrophil infiltration in the cutaneous Arthus reaction in mice. 125I-labeled rh-FcgammaRIA was cleared from mouse blood with a rapid distribution phase followed by a slow elimination phase with a t1/2gamma of approximately 130 h. The highest percentage of injected radioactivity accumulated in blood approximately liver approximately carcass>kidney. s.c. dosing of rh-FcgammaRIA resulted in lower serum levels of inflammatory cytokines and prevented paw swelling and joint damage in a murine model of collagen Ab-induced arthritis. These data demonstrate that rh-FcgammaRIA is an effective inhibitor of type III hypersensitivity.

Safety, pharmacokinetics and pharmacodynamics of atacicept in healthy volunteers.

OBJECTIVE: Atacicept, a recombinant fusion protein, blocks the activity of BLyS (a B-lymphocyte stimulator) and APRIL (a proliferation-inducing ligand) and may be a potential treatment for B-cell-mediated diseases. This study assesses the safety, pharmacokinetics (PK) and pharmacodynamics (PD) of atacicept. METHODS: In this Phase I study, healthy male volunteers received a single subcutaneous dose of atacicept (2.1, 70, 210 or 630 mg) or placebo and were monitored over 7 weeks for injection-site pain, local tolerability, vital signs, echocardiography, haematology, coagulation, blood chemistry, serum virology, urinalysis and PK/PD markers [lymphocyte cell counts, BLyS-atacicept complex, immunoglobulin G (IgG), IgM]. RESULTS: Atacicept was well tolerated at all doses (n = 23). There were no clinically significant changes in vital signs or laboratory parameters during the study. Treatment-emergent adverse events (AEs) were mainly mild or moderate in severity, and all were transient, resolving without any clinical sequelae. There was no evidence of any relationship between atacicept dose and the incidence of AEs. Local tolerability was good. Serum atacicept peaked 16 h after dosing, and the area under the concentration-time curve increased in an approximately dose-related manner. The 70-, 210- and 630-mg doses of atacicept demonstrated a dose-dependent biological effect on IgM levels, which was apparent up to 210 days post-dose. There were no treatment-related effects on IgG levels or lymphocyte subpopulations. CONCLUSIONS: These results showed that single subcutaneous doses of atacicept were well tolerated in healthy volunteers, demonstrated non-linear PK and were biologically active, according to IgM levels.

Preclinical safety of recombinant human thrombin.

Recombinant human thrombin (rhThrombin) is being developed as an alternative to thrombin products purified from pooled human or bovine plasma, which are currently marketed for topical hemostasis. Preclinical studies of rhThrombin were conducted prior to its evaluation as a topical adjunct to surgical hemostasis in clinical trials. No overt clinical pathology or signs were observed in cynomolgus monkeys following implantation of a gelatin sponge containing either rhThrombin or bovine thrombin to a surgical liver wound, and similar gross and microscopic wound healing characteristics were observed over an eight-week recovery period with either compound. Repeated subcutaneous injections of rhThrombin or bovine thrombin to cynomolgus monkeys produced no treatment-related effects. Whereas no monkeys demonstrated anti-rhThrombin antibody seroconversion, specific anti-bovine antibodies were detected in all tested monkeys exposed to bovine thrombin. Addition of rhThrombin or bovine thrombin to mouse fibroblast cells resulted in expected detachment and shape change. Topical application of rhThrombin to rabbits did not cause irritation to the eye, normal skin, or abraded skin. These studies showed that topical, subcutaneous, or implanted rhThrombin was minimally immunogenic, safe, and well tolerated in nonclinical models, and supported the clinical evaluation of rhThrombin in a variety of surgical settings.

Safety and pharmacokinetics of recombinant factor XIII-A2 administration in patients with congenital factor XIII deficiency.

Congenital factor XIII (FXIII) deficiency is associated with a tendency for severe bleeding, a risk for spontaneous abortion, and a high rate of spontaneous intracranial hemorrhage. This phase 1 escalating-dose study was developed to evaluate the safety and pharmacokinetics of a single administration of human recombinant FXIII-A2 (rFXIII-A2) homodimer in adults with congenital FXIII deficiency. Pharmacokinetics and activity of rXIII and changes in endogenous B subunit levels were assessed. Recombinant FXIII-A2 homodimer were complexed with endogenous FXIII-B subunits to form an FXIII-A2B2 heterotetramer with a half-life of 8.5 days, similar to that of endogenous FXIII. The median dose response was a 2.4% increase in FXIII activity based on unit per kilogram rFXIII administered. After the administration of rFXIII-A2, clot solubility normalized as measured by clot lysis in urea. Clot strength and resistance to fibrinolysis, as assessed by thromboelastography, also improved. Safety reviews were conducted before each dose escalation; no serious adverse events, including bleeding or thrombosis, were noted during the study. In addition, there was no evidence of the generation of specific antibodies to rFXIII or yeast proteins. Recombinant FXIII appears to be a safe and potentially effective alternative for FXIII replacement in patients with FXIII deficiency.