Efficacy, safety, and tolerability of lebrikizumab in adolescent patients with uncontrolled asthma (ACOUSTICS)

Background

Lebrikizumab is a monoclonal antibody that modulates activity of interleukin‐13. The Phase 3 ACOUSTICS study assessed lebrikizumab efficacy and safety in adolescents with uncontrolled asthma despite standard‐of‐care treatment.

Methods

Adolescents (aged 12–17 years) with uncontrolled asthma, prebronchodilator forced expiratory volume in 1 s 40%–90% predicted, and stable background therapy were randomised 1:1:1 to receive lebrikizumab 125 or 37.5 mg or placebo subcutaneously once every 4 weeks. Primary efficacy endpoint was asthma exacerbation rate over 52 weeks.

Results

Between August 2013 and July 2016, 579 patients were screened and 346 were randomised; 224 (65%) completed the study with 52 weeks of treatment. Lebrikizumab 125 mg (n = 116) reduced the exacerbation rate at 52 weeks versus placebo (n = 117; adjusted rate ratio [RR] 0.49 [95% CI 0.28–0.83]; 51% rate reduction). Lebrikizumab 37.5 mg (n = 113) was less effective at reducing exacerbations (RR 0.60 [95% CI 0.35–1.03]; 40% rate reduction). In patients with blood eosinophil counts ≥300 cells/μl, both lebrikizumab doses reduced exacerbations (125 mg: RR 0.44 [95% CI 0.21–0.89]; 37.5 mg: 0.42 [95% CI 0.19–0.93]). Treatment‐emergent adverse events, serious adverse events, and adverse events leading to study discontinuation occurred in 155 (68%), 7 (3%), and 5 (2%) of 229 patients who received lebrikizumab (both 125 and 37.5 mg doses) and in 72 (62%), 4 (3%), and 1 (1%) of 117 who received placebo, respectively. No deaths occurred.

Conclusion

Lebrikizumab 125 mg reduced asthma exacerbation rates in adolescents with uncontrolled asthma. However, the study was prematurely terminated (sponsor's decision) potentially limiting interpretation of results.

Clinical trial registration

NCT01875003 (www.ClinicalTrials.gov).

Population pharmacokinetics and exposure-response relationships of astegolimab in patients with severe asthma

Astegolimab is a fully human immunoglobulin G2 monoclonal antibody that binds to the ST2 receptor and blocks the interleukin‐33 signaling. It was evaluated in patients with uncontrolled severe asthma in the phase 2b study (Zenyatta) at doses of 70, 210, and 490 mg subcutaneously every 4 weeks for 52 weeks. This work aimed to characterize astegolimab pharmacokinetics, identify influential covariates contributing to its interindividual variability, and make a descriptive assessment of the exposure‐response relationships. A population pharmacokinetic model was developed using data from 368 patients in the Zenyatta study. Predicted average steady‐state concentration was used in the subsequent exposure‐response analyses, which evaluated efficacy (asthma exacerbation rate) and biomarker end points including forced expiratory volume in 1 second, fraction exhaled nitric oxide, blood eosinophils, and soluble ST2. A 2‐compartment disposition model with first‐order elimination and first‐order absorption best described the astegolimab pharmacokinetics. The relative bioavailability for the 70‐mg dose was 15.3% lower. Baseline body weight, estimated glomerular filtration rate, and eosinophils were statistically correlated with pharmacokinetic parameters, but only body weight had a clinically meaningful influence on the steady‐state exposure (ratios exceeding 0.8‐1.25). The exposure‐response of efficacy and biomarkers were generally flat with a weak trend in favor of the highest dose/exposure. This study characterized astegolimab pharmacokinetics in patients with asthma and showed typical pharmacokinetic behavior as a monoclonal antibody–based drug. The exposure‐response analyses suggested the highest dose tested in the Zenyatta study (490 mg every 4 weeks) performed close to the maximum effect, and no additional response may be expected above it.

Pharmacokinetics and exposure-efficacy relationships of omalizumab in patients with nasal polyps

The anti-immunoglobulin E (IgE) antibody, omalizumab (Xolair), is approved in the United States for the treatment of allergic asthma and chronic spontaneous urticaria, and has recently been studied for the treatment of nasal polyposis following completion of the two replicate phase 3 studies (POLYP 1 and POLYP 2). The dosing of omalizumab used in the phase 3 studies is based on a combination of patients' pre-treatment IgE level and body weight, similar to the approach used in allergic asthma. The objectives of the current analyses were to evaluate whether the pharmacokinetics (PK) of omalizumab and its pharmacodynamic (PD) effect on free and total IgE level in chronic rhinosinusitis with nasal polyps (CRSwNP) are consistent with those in allergic asthma via population PK/PD modeling and simulation, and to graphically explore exposure-response relationships and free IgE-response relationships in CRSwNP. Omalizumab PK and PD effect of total and free IgE in CRSwNP are generally consistent with those in asthma. Observed post-treatment free IgE suppressions were generally within the target range of the baseline IgE- and body weight-based omalizumab dosing table, with 74.2% and 93.0% of patients achieving a serum free IgE level below 25 ng/mL and 50 ng/mL, respectively at Week 24. Exposure-response analyses indicated that there was no clear correlation between omalizumab or free IgE concentration and key efficacy endpoints within the POLYP studies. Overall, these results indicate that the body weight and IgE-based dosing regimen of omalizumab was appropriate for use in CRSwNP patients.

Translational and pharmacokinetic-pharmacodynamic application for the clinical development of GDC-0334, a novel TRPA1 inhibitor

GDC‐0334 is a novel small molecule inhibitor of transient receptor potential cation channel member A1 (TRPA1), a promising therapeutic target for many nervous system and respiratory diseases. The pharmacokinetic (PK) profile and pharmacodynamic (PD) effects of GDC‐0334 were evaluated in this first‐in‐human (FIH) study. A starting single dose of 25 mg was selected based on integrated preclinical PK, PD, and toxicology data following oral administration of GDC‐0334 in guinea pigs, rats, dogs, and monkeys. Human PK and PK‐PD of GDC‐0334 were characterized after single and multiple oral dosing using a population modeling approach. The ability of GDC‐0334 to inhibit dermal blood flow (DBF) induced by topical administration of allyl isothiocyanate (AITC) was evaluated as a target‐engagement biomarker. Quantitative models were developed iteratively to refine the parameter estimates of the dose‐concentration‐effect relationships through stepwise estimation and extrapolation. Human PK analyses revealed that bioavailability, absorption rate constant, and lag time increase when GDC‐0334 was administered with food. The inhibitory effect of GDC‐0334 on the AITC‐induced DBF biomarker exhibited a clear sigmoid‐Emax relationship with GDC‐0334 plasma concentrations in humans. This study leveraged emerging preclinical and clinical data to enable iterative refinement of GDC‐0334 mathematical models throughout the FIH study for dose selection in subsequent cohorts throughout the study.

Comparability Considerations and Challenges for Expedited Development Programs for Biological Products

Expedited development programs for biological products to be used in the treatment of serious conditions bring about challenges because of the compressed clinical development timeframes. As expedited development does not lessen the quality expectations, one challenge is providing adequate chemistry, manufacturing, and control (CMC) information required to support approval of a biological product. In particular, the analytical comparability and, in some cases, pharmacokinetic comparability studies needed to bridge the clinical material to the commercial material could delay submission of applications for life-saving medicines. While there is the International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use (ICH) Topic Q5E guidance on assessing comparability of biological products before and after manufacturing changes, specific guidance on the emerging issue of conducting comparability exercises in the face of expedited drug development is lacking. In July 2019, clinical pharmacologists and product quality chemists from the US FDA and industry representatives convened an FDA workshop for a scientific exchange about considerations and challenges around conducting comparability exercises for expedited programs for biological products. This article highlights discussions from the workshop.

A randomized, placebo-controlled trial evaluating effects of lebrikizumab on airway eosinophilic inflammation and remodelling in uncontrolled asthma (CLAVIER)

BACKGROUND

The anti-interleukin 13 (IL-13) monoclonal antibody lebrikizumab improves lung function in patients with moderate-to-severe uncontrolled asthma, but its effects on airway inflammation and remodelling are unknown. CLAVIER was designed to assess lebrikizumab's effect on eosinophilic inflammation and remodelling.

OBJECTIVE

To report safety and efficacy results from enrolled participants with available data from CLAVIER.

METHODS

We performed bronchoscopy on patients with uncontrolled asthma before and after 12 weeks of randomized double-blinded treatment with lebrikizumab (n = 31) or placebo (n = 33). The pre-specified primary end-point was relative change in airway subepithelial eosinophils per mm2 of basement membrane (cells/mm2 ). Pre-specified secondary and exploratory outcomes included change in IL-13-associated biomarkers and measures of airway remodelling.

RESULTS

There was a baseline imbalance in tissue eosinophils and high variability between treatment groups. There was no discernible change in adjusted mean subepithelial eosinophils/mm2 in response to lebrikizumab (95% CI, -82.5%, 97.5%). As previously observed, FEV1 increased after lebrikizumab treatment. Moreover, subepithelial collagen thickness decreased 21.5% after lebrikizumab treatment (95% CI, -32.9%, -10.2%), and fractional exhaled nitric oxide, CCL26 and SERPINB2 mRNA expression in bronchial tissues also reduced. Lebrikizumab was well tolerated, with a safety profile consistent with other lebrikizumab asthma studies.

CONCLUSIONS & CLINICAL RELEVANCE

We did not observe reduced tissue eosinophil numbers in association with lebrikizumab treatment. However, in pre-specified exploratory analyses, lebrikizumab treatment was associated with reduced degree of subepithelial fibrosis, a feature of airway remodelling, as well as improved lung function and reduced key pharmacodynamic biomarkers in bronchial tissues. These results reinforce the importance of IL-13 in airway pathobiology and suggest that neutralization of IL-13 may reduce asthmatic airway remodelling.

CLINICAL TRIAL REGISTRATION

NCT02099656.

Efficacy and safety of lebrikizumab in adult patients with mild-to-moderate asthma not receiving inhaled corticosteroids

BACKGROUND

Asthma is a heterogeneous and complex disease in both its clinical course and response to treatment. IL-13 is central to Type 2 inflammation and contributes to many features of asthma. In a previous Phase 2 study, lebrikizumab, an anti-IL-13 monoclonal antibody, did not significantly improve FEV₁ in mild-to-moderate asthma patients not receiving ICS therapy. This Phase 3 study was designed to further assess the efficacy and safety of lebrikizumab in adult patients with mild-to-moderate asthma treated with daily short-acting β₂-agonist therapy alone.

METHODS

Adult patients with mild-to-moderate asthma were randomised to receive lebrikizumab 125 mg subcutaneously (SC), placebo SC, or montelukast 10 mg orally for 12 weeks, with an 8-week follow-up period. The primary efficacy endpoint was absolute change in pre-bronchodilator FEV₁ from baseline at Week 12.

FINDINGS

A total of 310 patients were randomised and dosed in the study. The mean absolute change in FEV₁ from baseline at Week 12 was higher in the lebrikizumab-treated arm compared with placebo (150 mL versus 67 mL); however, this improvement did not achieve statistical significance (overall adjusted difference of 83 mL [95% CI: -3, 170]; p = .06). Montelukast did not improve FEV₁ as compared with placebo. Lebrikizumab was generally safe and well tolerated during the study.

INTERPRETATION

Lebrikizumab did not significantly improve FEV₁ in mild-to-moderate asthma patients at a dose expected to inhibit the IL-13 pathway. Inhibiting IL-13 in this patient population was not sufficient to improve lung function. These data support the findings of a previous trial of lebrikizumab in patients not receiving ICS.

CLINICAL TRIALS REGISTRY NUMBER

This trial was registered under NCT02104674 at http://www.clinicaltrials.gov.

A Pharmacokinetic Bioequivalence Study Comparing Pirfenidone Tablet and Capsule Dosage Forms in Healthy Adult Volunteers

Introduction

Pirfenidone film-coated tablets were developed to offer an alternative to the marketed capsule formulation. This study assessed the bioequivalence of the tablet and capsule formulations under fed and fasted states.

Methods

A Phase I, open-label, randomized, four-treatment-period, four-sequence, crossover pharmacokinetics study (NCT02525484) was conducted. Each subject received an 801-mg single dose of pirfenidone as three 267-mg capsules or one 801-mg tablet under fasted and fed conditions. Pirfenidone plasma C_max, AUC_0–t and AUC_0–∞ were used to assess bioequivalence.

Results

Forty-four subjects were randomized to treatment. The 801-mg tablet in the fasted state met bioequivalence criteria [90% confidence intervals (CI) 80.00–125.00%] for the GLSM ratios of natural log-transformed C_max, AUC_0–t and AUC_0–∞. Under fed conditions, the 801-mg tablet met the bioequivalence criteria for AUC_0–t and AUC_0–∞, but slightly exceeded the bioequivalence criteria for the C_max (90% CI of 108.26–125.60%). The tablet C_max was approximately 17% higher than that of the capsules. In the fed state, the tablet C_max, and both AUC_0–t and AUC_0–∞ were reduced by 39% and 17%, respectively, relative to the fasted state. The tablet and capsules had acceptable tolerability profiles.

Conclusions

The pirfenidone 801-mg tablet met bioequivalence criteria when compared with three 267-mg capsules in the fasted state. The tablet C_max was slightly higher relative to capsules in the fed state, but this is not expected to have a clinically meaningful impact on the benefit–risk profile of pirfenidone.

Funding

This work was supported by F. Hoffmann-La Roche Ltd.

Electronic supplementary material

The online version of this article (doi:10.1007/s12325-017-0594-8) contains supplementary material, which is available to authorized users.

Model-based clinical pharmacology profiling and exposure-response relationships of the efficacy and biomarker of lebrikizumab in patients with moderate-to-severe asthma

Lebrikizumab is a humanized monoclonal antibody that binds to interleukin-13 and has been evaluated as a treatment for moderate-to-severe asthma. Objectives of this work were to characterize lebrikizumab pharmacokinetics (PK), identify influential covariates, and graphically explore exposure-response relationships in moderate-to-severe asthmatics. Pooled PK data from 11 studies were used in the population PK model development. Full covariate modeling was used to evaluate the impact of pre-specified covariates. Response data (exacerbation rate, forced expiratory volume in 1 s [FEV₁], and fractional exhaled nitric oxide [FeNO]) were obtained from moderate-to-severe asthmatics (n = 2148) who received placebo, lebrikizumab 37.5 mg or 125 mg every 4 weeks (Q4W) in two replicate phase 3 studies. Graphical exposure-response analyses were stratified by numerous covariates, including biomarker subgroups defined by serum periostin level and blood eosinophil count at baseline. Lebrikizumab PK was described by a two-compartment model with first-order absorption. Population typical values were estimated as 0.156 L/day for clearance (CL), 4.10 L for central volume (Vc), and 0.239 day^-1 for absorption rate (ka), 85.6% for bioavailability (inter-subject variability: CL, 33.3%; Vc, 36.3%; ka, 40.8%). The estimated mean terminal half-life was 25.7 days. Body weight was the most influential covariate. Generally, the exposure-response analyses of FEV₁ and FeNO showed increased response at higher exposure quartiles, while flat or unclear exposure-response relationships were observed in exacerbation rate. Lebrikizumab PK is as expected for a typical immunoglobulin G4 monoclonal antibody. Results from the exposure-response analyses suggested that, compared to 125 mg Q4W, the 37.5 mg Q4W dose did not achieve the maximum responses for FEV₁ and FeNO, although it appeared to maximize the effect on exacerbation reduction. This suggests that the antibody levels needed to improve these outcomes may not be the same. In addition, the role of IL-13 in airflow obstruction/airway inflammation and asthma exacerbations might be different and targeting multiple pathways may be required to treat this heterogeneous disease and provide clinically meaningful benefits to asthma patients.

Lebrikizumab in moderate-to-severe asthma: pooled data from two randomised placebo-controlled studies

Introduction

In a subset of patients with asthma, standard-of-care treatment does not achieve disease control, highlighting the need for novel therapeutic approaches. Lebrikizumab is a humanised, monoclonal antibody that binds to and blocks interleukin-13 activity.

Methods

LUTE and VERSE were replicate, randomised, double-blind, placebo-controlled studies, evaluating multiple doses of lebrikizumab in patients with uncontrolled asthma despite the use of medium-to-high-dose inhaled corticosteroid and a second controller. Patients received lebrikizumab 37.5, 125, 250 mg or placebo subcutaneously every four weeks. The primary endpoint was the rate of asthma exacerbations during the placebo-controlled period. Analyses were performed on prespecified subgroups based on baseline serum periostin levels. Following the discovery of a host-cell impurity in the study drug material, protocols were amended to convert from phase III to phase IIb. Subsequently, dosing of study medication was discontinued early as a precautionary measure. The data collected for analysis were from a placebo-controlled period of variable duration and pooled across both studies.

Results

The median duration of treatment was approximately 24 weeks. Treatment with lebrikizumab reduced the rate of asthma exacerbations, which was more pronounced in the periostin-high patients (all doses: 60% reduction) than in the periostin-low patients (all doses: 5% reduction); no dose–response was evident. Lung function also improved following lebrikizumab treatment, with greatest increase in FEV₁ in periostin-high patients (all doses: 9.1% placebo-adjusted improvement) compared with periostin-low patients (all doses: 2.6% placebo-adjusted improvement). Lebrikizumab was well tolerated and no clinically important safety signals were observed.

Conclusions

These data are consistent with, and extend, previously published results demonstrating the efficacy of lebrikizumab in improving rate of asthma exacerbations and lung function in patients with moderate-to-severe asthma who remain uncontrolled despite current standard-of-care treatment.

Trial registration numbers

The LUTE study was registered under NCT01545440 and the VERSE study under NCT01545453 at http://www.clinicaltrials.gov

Targeting membrane-expressed IgE B cell receptor with an antibody to the M1 prime epitope reduces IgE production

Elevated serum levels of both total and allergen-specific immunoglobulin E (IgE) correlate with atopic diseases such as allergic rhinitis and allergic asthma. Neutralization of IgE by anti-IgE antibodies can effectively treat allergic asthma. Preclinical studies indicate that targeting membrane IgE-positive cells with antibodies against M1 prime can inhibit the production of new IgE and significantly reduce the levels of serum IgE. We report results from two trials that investigated the safety, pharmacokinetics, and activity of quilizumab, a humanized monoclonal antibody targeting specifically the M1 prime epitope of membrane IgE, in subjects with allergic rhinitis (NCT01160861) or mild allergic asthma (NCT01196039). In both studies, quilizumab treatment was well tolerated and led to reductions in total and allergen-specific serum IgE that lasted for at least 6 months after the cessation of dosing. In subjects with allergic asthma who were subjected to an allergen challenge, quilizumab treatment blocked the generation of new IgE, reduced allergen-induced early and late asthmatic airway responses by 26 and 36%, respectively, and reduced allergen-induced increases in sputum eosinophils by ~50% compared with placebo. These studies indicate that targeting of membrane IgE-expressing cells with anti-M1 prime antibodies can prevent IgE production in humans.

The effects of lebrikizumab in patients with mild asthma following whole lung allergen challenge

Background

Interleukin 13 (IL13) is a T-helper type 2 (Th2) cytokine associated with inflammation and pathology in allergic diseases such as bronchial asthma. We have shown that treatment with lebrikizumab, an anti-IL13 monoclonal antibody, significantly improves prebronchodilator forced expiratory volume in 1 s (FEV₁) in a subset of subjects with uncontrolled asthma.

Objective

To evaluate efficacy and safety of lebrikizumab in subjects with mild asthma who underwent bronchial allergen challenge.

Methods

Twenty-nine subjects were randomized 1: 1–5 mg/kg lebrikizumab (n = 13) or placebo (n = 16) administered subcutaneously every 4 weeks over 12 weeks, a total of four doses. Primary efficacy outcome was late asthmatic response (LAR) at Week 13, defined as area under the curve of FEV₁ measured 2–8 h following inhaled allergen challenge. Serum biomarkers were measured to verify IL13 pathway inhibition and identify patients with an increased response to lebrikizumab.

Results

At Week 13, the LAR in lebrikizumab subjects was reduced by 48% compared with placebo subjects, although this was not statistically significant (95% confidence interval, −19%, 90%). Exploratory analysis indicated that lebrikizumab-treated subjects with elevated baseline levels of peripheral blood eosinophils, serum IgE, or periostin exhibited a greater reduction in LAR compared with subjects with lower baseline levels of these biomarkers. Lebrikizumab exerted systemic effects on markers of Th2 inflammation, reducing serum immunoglobulin E (IgE), chemokine ligands 13 and 17 by approximately 25% (P < 0.01). Lebrikizumab was well tolerated.

Conclusion and Clinical Relevance

Lebrikizumab reduced the LAR in subjects with mild asthma. Clinical trial number NCT00781443.

Effect of antigen binding affinity and effector function on the pharmacokinetics and pharmacodynamics of anti-IgE monoclonal antibodies

Modulating the binding affinities to IgE or changing the FcγR binding properties of anti-IgE antibodies offers an opportunity to enhance the therapeutic potential of anti-IgE antibodies, but the influence of increased affinity to IgE or reduced Fc effector function on the pharmacological properties of anti-IgE therapies remains unclear. Our studies were designed to characterize the pharmacokinetics, pharmacodynamics and immune-complex distribution of two high-affinity anti-IgE monoclonal antibodies, high-affinity anti-IgE antibody (HAE) 1 and 2, in mice and monkeys. HAE1, also known as PRO98498, is structurally similar to omalizumab (Xolair®), a humanized anti-IgE IgG1 marketed for the treatment of asthma, but differs by 9 amino acid changes in the complementarity-determining region resulting in a 23-fold improvement in affinity. HAE2 is similar to HAE1, but its Fc region was altered to reduce binding to Fcγ receptors. As expected given the decreased binding to Fcγ receptors, systemic exposure to pre-formed HAE2:IgE complexes in mice was greater (six-fold) and distribution to the liver lower (four-fold) compared with HAE1:IgE complexes. In monkeys, systemic exposure to HAE1 was similar to that previously observed for omalizumab in this species, but required comparatively lower serum drug concentrations to suppress free IgE levels. HAE2 treatment resulted in greater exposure and greater increase of total IgE, relative to HAE1, because of decreased clearance of HAE2:IgE complexes. Overall, these data suggest that increased binding affinity to IgE may provide a more effective therapeutic for asthma patients, and that retaining FcγR binding of the anti-IgE antibody is important for elimination of anti-IgE:IgE complexes.

Dose-ranging study of lebrikizumab in asthmatic patients not receiving inhaled steroids

BACKGROUND

Asthma is a disease with marked heterogeneity in its clinical course and response to treatment. IL-13 is central to type 2 inflammation, which contributes to many key features of asthma. Lebrikizumab is an anti-IL-13 mAb previously reported to significantly improve lung function in patients with inadequately controlled asthma despite inhaled corticosteroid therapy, especially in periostin-high patients.

OBJECTIVE

This phase II study investigated the efficacy and safety of IL-13 blockade with different doses of lebrikizumab in asthmatic patients not receiving inhaled corticosteroids.

METHODS

Patients were randomized to receive 125, 250, or 500 mg of lebrikizumab or placebo subcutaneously monthly for 12 weeks with an 8-week follow-up period. The primary efficacy end point was the relative change in prebronchodilator FEV1 from baseline to week 12.

RESULTS

A total of 212 patients were randomized. The mean relative change in FEV1 was numerically higher in all lebrikizumab dose groups versus the placebo group, although the difference was neither statistically nor clinically significant. There were no meaningful differences in changes in FEV1 between the dose groups and the placebo group by the periostin subgroup. Lebrikizumab treatment was associated with a reduced risk of treatment failure at all doses versus placebo (P < .001), and results were similar by the periostin subgroup, with no apparent differences between doses of lebrikizumab. Lebrikizumab was generally well tolerated.

CONCLUSION

Blocking IL-13, a single cytokine, in this population of asthmatic patients is insufficient to improve lung function. There is evidence that IL-13 blockade may improve disease control, as measured by prevention of protocol-defined treatment failure in these patients.

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.

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.

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 (</=10 IU/ml). The simulation platform enabled selection of four doses for the phase II dose-ranging trial by two independent methods: dose-response non-linear fitting and linear mixed modeling. Agreement between the two methods provided confidence in the doses selected. Modeling and simulation played a large role in supporting acceleration of the HAE1 program by enabling data-driven decision-making, often based on confirmation of projections and/or learning from incoming new data.

Effect of the MDR1 C3435T variant and P-glycoprotein induction on dicloxacillin pharmacokinetics

This study investigated 2 hypotheses about genotype-phenotype relationships for the efflux transporter, P-glycoprotein: (1) the presence of a synonymous C3435T variant in exon 26 of the MDR1 gene correlates to higher plasma concentrations of a P-glycoprotein substrate, dicloxacillin, and (2) the effects of genotypic differences decrease under conditions of P-glycoprotein induction by rifampin. Eighteen healthy volunteers received two 1-g doses of dicloxacillin, one on the 1st study day and the other on the 11th day of rifampin dosing (600 mg daily). Dicloxacillin and its 5-hydroxymethyl metabolite were analyzed using liquid chromatography/tandem mass spectrometry. Mean dicloxacillin C(max) measurements were 30.5 +/- 13.5, 33.3 +/- 4.7, and 31.1 +/- 12.8 mug/mL in individuals with the CC, CT, and TT genotype at position 3435 in exon 26 of the MDR1 gene. Following rifampin dosing, the mean dicloxacillin C(max) across genotypes decreased from 31.4 +/- 10.8 to 22.9 +/- 7.0 microg/mL (P < .05), whereas the mean oral clearance increased from 235 +/- 82 to 297 +/- 71 mL/min (P < .001), and the mean absorption time increased from 0.71 +/- 0.55 to 1.34 +/- 0.77 h (P < .05). Rifampin treatment increased the formation clearance, C(max), and AUC of the 5-hydroxymethyl metabolite by 135%, 119%, and 59%, respectively. The C3435T variant had no effect on dicloxacillin pharmacokinetics. The data suggested that rifampin induced intestinal P-glycoprotein and increased dicloxacillin metabolism.

Functional characterization of monocarboxylic acid, large neutral amino acid, bile acid and peptide transporters, and P-glycoprotein in MDCK and Caco-2 cells

Bidirectional transport studies were conducted to determine whether substrates of five intestinal transporters showed carrier-mediated asymmetric transport across MDCK (Madin-Darby canine kidney) cell monolayers grown under standard conditions. Drug concentrations were quantitated using liquid scintillation counting, liquid chromatography/mass spectrometry/mass spectrometry, or liquid chromatography/mass spectrometry. In the presence of a pH gradient, benzoic acid exhibited net apical-to-basolateral transport, with apparent permeability ratios (apical-to-basolateral permeability/basolateral-to-apical permeability) ranging from 14 to 25. The addition of valproic acid reduced the permeability ratio by 70-90%. Cephalexin transport also exhibited net absorption in the presence of a pH gradient, with apparent permeability ratios ranging from 14 to 71, depending on growth conditions. Radiolabeled phenylalanine exhibited a low level of carrier-mediated absorption with an apparent permeability ratio of 1.8 that was reduced to 1.0 in the presence of unlabeled L-phenylalanine. Taurocholic acid did not exhibit carrier-mediated absorption. Cyclosporine and fexofenadine exhibited P-glycoprotein-mediated efflux from both MDCK and Caco-2 cells, which was more sensitive to inhibition in MDCK cells. These results suggest that although MDCK cell monolayers may be a useful model for evaluating transport by the absorptive monocarboxylic acid and peptide transporters and the efflux transporter, P-glycoprotein, they are not useful for predicting large neutral amino acid or bile acid transport in the intestine.

Comparison of bidirectional cephalexin transport across MDCK and caco-2 cell monolayers: interactions with peptide transporters

PURPOSE

Bidirectional transport studies were conducted to determine whether Madin-Darby canine kidney (MDCK) cell monolayers could be used as an alternative to the traditional Caco-2 assay as a fast-growing in vitro model of peptide transport.

METHODS

Transport of cephalexin and glycylsarcosine across MDCK and Caco-2 cell monolayers was quantified using LC-LC/MS. Glycylsarcosine, p-aminohippuric acid (PAH), and tetraethylammonium chloride (TEA) were tested as inhibitors of cephalexin transport.

RESULTS

The ratio of apparent cephalexin permeabilities (apical to basolateral/basolateral to apical) obtained from MDCK monolayers was almost 5-fold greater than that obtained from Caco-2 monolayers. The opposite trend was observed for glycylsarcosine. When MDCK monolayers were used, glycylsarcosine reduced the cephalexin/apparent permeability ratio almost 90%. PAH and TEA did not inhibit cephalexin transport across MDCK or Caco-2 cell monolayers.

CONCLUSION

MDCK cell monolayers may be a promising, fast-growing alternative to Caco-2 cells for identifying peptide transporter substrates. However, differences in the apical-to-basolateral transport of cephalexin and glycylsarcosine suggest that the basolateral transport mechanisms for these compounds are different in the two cell lines. Additionally, because the activity of the peptide transporter in MDCK cells was low, scaling factors may be required when using this cell line to predict in vivo drug absorption.

Endoscopic laser lithotripsy of large bile duct stones

Experimental work has established that the Candela (Candela Laser Corporation, Wayland, MA) flashlamp excited dye laser (wavelength, 504 nm) is a highly effective method for fragmenting biliary stones and has minimal potential for injuring the bile duct wall. This technique was evaluated in 25 complex patients whose stones, usually because of large size, did not respond to standard nonoperative treatment. The laser imaging was applied through a quartz fiber and aimed either under direct vision with choledochoscopes passed percutaneously or through a special "mother" duodenoscope or under fluoroscopic guidance at standard duodenoscopy. Laser treatment resulted in some fragmentation of stones in 23 cases. Subsequently, it proved that it was possible to clear the bile duct of stones in 20 patients, 12 of them receiving successful treatment during the same endoscopic procedure. There were no significant complications. This endoscopic technique seems to be a useful new alternative to surgery in patients with large and difficult bile duct stones.

Inhibitory regulation of rat exocrine pancreas by peptide YY and pancreatic polypeptide

Peptide YY (PYY) and pancreatic polypeptide (PP) have been shown to inhibit exocrine pancreatic secretion in vivo in a variety of species. This study evaluates the type of stimulation inhibited by PYY and PP by examining, in urethan-anesthetized rats, the inhibition of pancreatic secretion when stimulated to a comparable extent by cholecystokinin (CCK), 2-deoxy-D-glucose (2DG), bethanecol, and electrical vagal nerve stimulation. PYY at maximal infusion rates inhibited stimulation by CCK by 83%, bethanecol by 55%, and electrical nerve stimulation by 40%. The inhibition of CCK stimulation was half maximal at 250 pmol.kg-1.h-1. By contrast, PYY totally inhibited 2DG-stimulated secretion with half-maximal inhibition at 10 pmol. kg-1.h-1. PP acted similarly to PYY in inhibiting CCK and 2DG-stimulated pancreatic protein secretion but was fivefold weaker in each case. These findings indicate that PYY and PP have multiple actions but preferentially inhibit neurally mediated pancreatic secretion at a preacinar cell locus, possibly at a central site of action.

The hepatic extraction of gastric inhibitory polypeptide and insulin

The hepatic extractions of gastric inhibitory polypeptide (GIP) and insulin were determined using in vitro and in vivo methods to assess the role of the liver in GIP metabolism and the possible effect of GIP on the hepatic extraction of insulin. During in vitro studies using the isolated perfused rat liver, infusion of GIP (2000 pg/ml) alone and in combination with porcine insulin (200 microU/ml) resulted in negligible hepatic extraction of immunoreactive GIP (IR-GIP) in both fed and fasted animals during either physiologically euglycemic or hyperglycemic perfusions. Hepatic extraction of insulin, however, ranged from 26-36% in fasted animals and from 7-25% in fed animals. Hepatic extraction of insulin and net hepatic glucose appearance were minimally affected by GIP. In vivo studies in awake dogs were then performed, in which simultaneous portal and peripheral venous levels of IR-GIP, immunoreactive insulin (IRI), and glucose were assessed after intraduodenal glucose administration. The portal to peripheral (PORT/PERI) venous ratio of endogenous IRI and IR-GIP reflected the findings of the in vitro studies; the PORT/PERI ratio of IRI levels rose from a basal value of 1.9 +/- 0.3 to a peak of 3.7 +/- 0.9, while the PORT/PERI ratio of IR-GIP levels rose from a basal value of 1.0 +/- 0.1 to a peak of 1.4 +/- 0.2, then rapidly returned to 1.0. The in vivo data are consistent with a continuous hepatic extraction of 40-50% of the insulin entering the liver and a negligible hepatic extraction of IR-GIP. We conclude that hepatic extraction of GIP in vitro or in vivo is minimal. In addition, while the fed state of the animal before infusion can result in changes in the in vitro hepatic extraction of insulin, GIP does not mediate these changes.

Selective potentiation of insulin-mediated glucose disposal in normal dogs by the sulfonylurea glipizide

Investigative data have suggested that the extrapancreatic actions of the sulfonylureas may be paramount in their chronic antidiabetic action. The present study examines the effects of chronic sulfonylurea treatment on in vivo insulin action. Peripheral insulin levels, hepatic glucose production (Ra), and overall glucose disposal (Rd) were studied in six awake, normal dogs given both 0.5 and 1.0 mU/kg per min pork insulin for 2.5 h. This produces stable hyperinsulinemia from 15 to 150 min. Fasting euglycemia was held constant by the glucose clamp technique and averaged 99% basal glucose in all studies. Ra and Rd were determined from infusion of [3-(3)H]glucose, begun 90 min prior to insulin infusion. 10 mg of the sulfonylurea glipizide, was given daily to the test animals for the 10 to 20 d following appropriate control studies, then was withheld for 24 h, and the dogs were restudied. Glipizide treatment did not significantly alter basal glucose turnover, Ra, mean glucose values, or mean insulin levels as determined by radioimmunoassay. Increase in Rd above basal glucose turnover in response to insulin (delta Rd) was significantly (P less than 0.05) increased by glipizide treatment at both insulin dosage levels (paired analysis). At 1.0 mU/kg per min insulin, delta Rd rose from 2.6 mg/kg per min before glipizide to 6.5 mg/kg per min after glipizide treatment. At 0.5 mU/kg per min insulin, delta Rd went from 1.1 mg/kg per min before glipizide to 2.2 mg/kg per min after glipizide treatment. Glipizide treatment doubled the effects of insulin on Rd, while showing no significant effect upon insulin suppression of Ra. We conclude that a significant extrapancreatic chronic action of glipizide lies in its ability to selectively potentiate Rd.