medwireNews: Measuring CD11b-positive (CD11b+) monocytes could help estimate how many anti-vascular endothelial growth factor (VEGF) injections a patient with neovascular age-related macular degeneration (AMD) or polypoidal choroidal vasculopathy (PCV) might need, study findings suggest.
The results, published in JAMA Ophthalmology, showed that the CD11b+ monocyte count in 81 patients diagnosed with AMD or PCV correlated with the future number of anti-VEGF injections needed at 12, 24, and 36 months in univariate linear regression analysis, with the strength of the association ranging from 0.77 to 0.82.
The patients were given injections at a loading dose of ranibizumab 0.05 mL or aflibercept 0.05 mL on 3 consecutive months, after which injections were given as needed according to retreatment criteria based on the presence of subretinal or intraretinal fluid, or new or persisting retinal haemorrhage.
The mean proportion of monocytes positive for CD11b, which is expressed on the surface of myeloid cells and facilitates cell adhesion and migration, especially at sites of inflammation, was 89.9% at baseline.
CD11b+ monocytes continued to reflect the number of anti-VEGF injections at each time point in a multiple regression model, with baseline best corrected visual acuity (BCVA) being the only other predictive variable.
Receiver operating characteristic curve analysis showed that CD11b+ monocyte count could correctly classify those patients needing less than 12 versus 12 or more injections at 36 months on 100% of occasions.
“We propose that CD11b+ on circulating monocytes may provide insight into disease prognosis and give patients some insight into what can be expected in terms of long-term need for intravitreal therapy”, Yousif Subhi (Zealand University Hospital, Roskilde, Denmark) and colleagues write.
The association was treatment independent with a similar degree of correlation seen in patients treated with ranibizumab and aflibercept, bar a nonsignificant association at 12 months among patients taking aflibercept.
Indeed, the correlation between CD11b+ monocytes and anti-VEGF injections tended to strengthen with time, as the variation in injections became greater, which the researchers say suggests it may be related more to treatment adherence, retinal injury and subretinal fibrosis than with the clinical measures of BCVA or central retinal thickness.
The association between CD11b+ monocytes and anti-VEGF injections was also not specific to AMD and its existence in patients with PCV “suggests that the association may be more fundamentally related to the systemic contribution to CNV [choroidal neovascularization]”, rather than immunological aging or dysfunction.
“The association identified in this investigation between the application of anti-VEGF injections and the proportion of circulating CD11b+ monocytes suggests that targeting these monocytes, directly or indirectly, may help identify novel therapeutics against CNV-dominated diseases”, say the researchers.
They acknowledge, however, that “additional longitudinal studies would be needed to determine whether these findings have clinical relevance to influence treatment algorithms or provide novel targets for medical therapy.”
By Lucy Piper
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