Improved adalimumab dose decision with comprehensive diagnostics data.

OBJECTIVES: Monoclonal antibodies are important in the treatment of rheumatoid arthritis (RA). This is the first trial to monitor the effect of adalimumab dose escalation in persistently active RA. The aim of this study was to identify the response to adalimumab to improve the basis for making decision in relation to actual drug capacity in serum. METHODS: The disease activity of RA patients was assessed with CDAI and DAS28 before administration of additional 40 mg adalimumab one week after standard injection. Serum samples were analysed using the recoveryELISA technology, a combination of sandwich ELISA and competitive assay. The recoveryELISA measure the concentrations of free TNF-α, drug level, and the remaining active adalimumab in the patients' sera. An adalimumab concentration of 5.0-10.0 g/mL was defined as the targeted therapeutic window. RESULTS: Five of 8 patients achieved moderate EULAR response by dose escalation. The results of the free adalimumab and TNF-α neutralisation measurements allowed a separation of the cohort (n=17) into three groups. Group 1 represents 18% of the patients with free adalimumab level higher 30.0 µg/mL and TNF-α neutralisation above 95%. Group 2 (47%) consists of patients within the therapeutic window with balanced free adalimumab and TNF-α neutralisation values. Group 3 contains 35% of the cohort with low concentrations of free adalimumab and lowest remaining TNF-α-neutralisation capacity. Anti-drug antibodies were detected in four patients but did not prevent response to treatment. CONCLUSIONS: Drug and antigen monitoring using recoveryELISA may support dose decision to avoid unnecessary switch in medication or possible overtreatment.

The recovery-ELISA--a novel assay technique to monitor therapy with humanized antibodies: the example of omalizumab.

The therapeutic use of antibodies has grown exponentially, providing new treatment options for various diseases. Monitoring treatment with therapeutic antibodies is a particular challenge because often the target antigen is no longer measurable or the results are unreliable. To overcome this problem, a recovery-ELISA was developed to quantify therapeutic antibody and antigen by a modification of the traditional sandwich immunoassay using omalizumab as an example. Standard serum samples were spiked with IgE and omalizumab in a certain concentration range to create standard curves. After incubation and washout procedures, the reaction was stopped and the plate read with bichromatic absorbance. This approach defines reference functions for serum IgE without and with antibody, respectively. Based on these functions, free IgE and omalizumab concentrations can be calculated in serum samples of patients treated with omalizumab. The recovery-ELISA allows us to easily quantify antigen (free IgE) and therapeutic antibody (omalizumab) simultaneously in the same sample and thus to monitor patients treated with the specific antibody.

The recoveryELISA--a newly developed immunoassay for measurement of therapeutic antibodies and the target antigen during antibody therapy.

Therapeutic antibodies are an important part of Biopharmaceuticals. They are highly innovative and specific drugs. Additionally, they play a challenging role in new demands in diagnostics because they disturb conventional antibody-based tests, such as immunoassays. The recoveryELISA is a newly developed immunoassay technology for monitoring such therapeutic antibodies or comparable biologics during the therapy. The recoveryELISA determines three results in one test: the free level of antigen (if available in serum), the level of therapeutic antibody and the specific dose-response interaction. The free level of antigen is the amount that can be measured in the immunoassay, as it exists unmasked under assay conditions. The relationship between therapeutic antibody level and neutralization rate of target protein is shown by the so-called 'recovery curve'. The recoveryELISA is demonstrated with the example of Omalizumab/IgE.

Monitoring free serum IgE in severe asthma patients treated with omalizumab.

BACKGROUND: Benefit of treatment with the monoclonal anti-IgE-antibody omalizumab in severe IgE-dependent asthma requires a significant reduction of serum free IgE concentrations. It is unclear if monitoring free serum IgE is clinically meaningful once omalizumab treatment is initiated. METHODS: Free IgE and omalizumab serum concentrations were quantified in 22 patients with severe asthma (68% female, 47 ± 11 yrs, mean (±SD) pre-bronchodilator FEV(1) 62 ± 13%, baseline mean (±SEM) free serum IgE 652 ± 136 ng/ml) treated with omalizumab for 4 months using a Recovery-ELISA. RESULTS: Omalizumab treatment reduced free serum IgE prior to the second omalizumab injection by 73%, after 16 weeks by 81% to 58 ± 12 ng/ml (p < 0.001 vs. baseline). 17 patients responded to anti-IgE therapy as judged by physician-rated global evaluation of treatment effectiveness. There was neither a relation between free serum IgE concentrations and treatment response nor a significant or clinically relevant correlation between free IgE levels and changes in lung function, exhaled NO, asthma control, and quality of life. Serum concentrations of omalizumab were detected in all patients and reached a stable phase within 8 weeks. CONCLUSIONS: Monitoring free IgE and omalizumab serum concentrations in patients treated with omalizumab does not predict clinical response nor does it add to the decision to continue or stop treatment. However, routine measurements of free IgE may be clinically relevant to demonstrate an adequate reduction in free IgE in patients not responding to omalizumab therapy.