Despite some reports to the contrary, it is generally assumed that early-onset forms of periodontal disease (including both juvenile and rapidly progressive periodontitis) are associated with a defect in neutrophil (PMN) chemotactic behaviour. Using the Boyden chamber technique and N-formyl-methionyl-leucylphenylalanine (FMLP) to assess locomotion by the leading front method, we have failed to show any evidence for such depressed PMN locomotion. Indeed, when PMN chemotaxis and chemokinesis are considered in response to a range of chemoattractant doses our results indicate significant enhancement of all but random locomotion. When taken together with other studies, our results suggest that PMNs from patients with early-onset periodontitis may show abnormal locomotory behaviour which can either be enhanced or reduced in nature. The extent to which these results reflect in vitro methodology in uncertain and, furthermore, their in vivo significance is unclear.
The locomotory behaviour of peripheral blood neutrophils (PMNs) from patients with juvenile (JP) and rapidly progressive (RPP) forms of early-onset periodontal disease was studied using the under agarose technique and n-formyl-methionyl-leucyl-phenylalanine (FMLP) as the chemotractant. PMNs from experimental patients showed normal random, chemotactic and chemokinetic locomotory behaviour when compared with control subjects. Further investigation of single-cell movements using time-lapse video analysis also failed to show any significant differences in locomotory behaviour between the PMNs of experimental and control individuals. We conclude that differences in technique may account for much of the variation which exists in the literature with respect to PMN locomotion in periodontal disease. In the final analysis, it is difficult to dispute direct observation of moving cells, and using this approach, we have been unable to confirm the presence of any PMN locomotory defect in our series of patients with early-onset periodontal disease.
Abelacimab is a fully human IgG1 monoclonal antibody that has dual activity against the inactive zymogen Factor XI (FXI) and the activated Factor XI (FXIa). Clinical trials for this investigational product are ongoing.
As part of the initial assessment of abelacimab safety and efficacy, an anti-drug antibody (ADA) assay was validated and implemented in two single ascending dose studies conducted in the United States and Japan in healthy subjects. In those studies, ADA positive results were detected in up to 31.1% of subjects. There was no apparent impact on PK, PD, or development of immunogenicity-adverse events in study subjects who were ADA positive relative to those who were ADA negative in either study. Further, the rates of ADA positive subjects seemed inconsistent with a single administration of a fully human IgG1 monoclonal antibody therapeutic. Given the homodimeric structure of FXI, it appeared that the ADA assay was returning false positive results due to cross-linking through FXI. To address this issue, a novel ADA assay, following the 3-tiered approach of screening, confirmation, and titer determination was developed and validated. The assay was shown to be sensitive, specific, and did not show false positive interference by FXI. Two subsequent clinical trials (ANT-003 A randomized, subject- and investigator-blinded, placebo-controlled study conducted in healthy subjects and in obese, but otherwise healthy, subjects aged 18 to 60 years of age and ANT-004 A randomized, subject- and investigator-blinded, placebo-controlled, multiple ascending dose study in patients with atrial fibrillation (AF) or atrial flutter aged 18 to 85 years old with a CHA 2DS 2-VASc risk score of 0-1 for men and 1-2 for women and in whom the use of an anticoagulant for stroke prevention was not planned for the duration of the trial) showed no treatment-emergent ADA responses from either trial. The screen positive rate from the two studies was approximately 5% with no screen positive samples confirmed as positive indicating that the new assay format successfully addressed the false positive issue, and that the sensitivity was appropriately set to achieve the FDA-recommended 5% false positive rate for ADA assays.
Disclosures
Cullen: Anthos Therapeutics, Inc: Consultancy. Freedholm: Anthos Therapeutics, Inc: Current Employment, Current holder of stock options in a privately-held company.
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