Novel needle for intravitreal injections does not affect biological activity of anti-VEGF drugs

Abstract

Purpose: In this in vitro study, we investigated if the biological activity of commonly used VEGF antagonists might be affected by their passage through a newly designed 30 G needle (NDN) for intravitreal injection (IVI). To reduce the risk of intraocular inflammation compared to conventional injection with a standard hypodermic 30 G needle (SHN), the NDN contains an occluded front orifice and a side port for drug delivery, resulting in an altered direction of the injection stream. Methods: Anti-VEGF drugs, such as ranibizumab, faricimab, and aflibercept, were passed twice through one of the two needle types to imitate IVI. To evaluate the VEGF-A-binding capacity of the un- or pretreated antagonists, VEGF-A165 was incubated with a 1–10fold molar excess of them for 15 min at 37°C, and unbound VEGF-A was determined by ELISA. As the capture antibody and antagonists bind to the same region of the growth factor, only the non-complexed VEGF-A was measured. Biological activity of pretreated antagonists was studied by assessing their capacity to prevent VEGF-A165-induced impairment of the barrier formed by retinal endothelial cells: VEGF-A165 plus antagonists were added to the cells and, as a measure of permeability, the cell index was continuously monitored by electric cell-substrate impedance measurements for three days. Results: Only a marginal amount of free VEGF-A, if any, was detected after incubation of the growth factor with a fourfold molar excess of any of the antagonists, independent of the drugs’ pretreatment. VEGF-A165-induced low cell index values, indicative of a dysfunctional barrier, were similarly prevented by different pretreated antagonists. Conclusion: The passage of the proteins through NDN or SHN did neither affect efficient binding to their target, nor their capacity to prevent VEGF-A165-induced barrier dysfunction. Overall, regarding the stability of therapeutic proteins, the NDN was not inferior to the SHN, and can now be considered for evaluation in clinical studies.