medwireNews: Decreased cytokine concentrations in the aqueous humour are associated with a response to treatment with anti-vascular endothelial growth factor (VEGF) agents in patients with diabetic macular oedema (DME), study data show.
Rajeev Muni (University of Toronto, Ontario, Canada) and colleagues say that their “findings suggest that aqueous humour cytokine concentrations may serve as an early biomarker of eyes that will likely demonstrate poor response to long-term anti-VEGF therapy.”
They add: “Early recognition of response to anti-VEGF enables timely switch of treatments or consideration of alternate therapy for targeting cytokines that play a role in the inflammatory pathogenesis of DME independently of VEGF.”
Muni and team reviewed data for 41 treatment-naïve eyes with centre-involving DME that were treated with intravitreal anti-VEGF injections.
During 51.4 months of follow-up, 85.4% of the eyes were classified as responders based on qualitative assessment of optical coherence tomography, which indicated a reduction or resolution of the intraretinal and/or subretinal fluid following an anti-VEGF injection.
The remaining 14.6% were identified as nonresponders according to an increased central subfield thickness and macular volume at two or more consecutive visits despite ongoing intravitreal anti-VEGF injections. Eyes with persistent DME that switched from anti-VEGF injections to corticosteroid therapy were also classed as nonresponders.
During the first 2 months of treatment, the researchers observed that eyes in both the responder and nonresponder groups had a significant decrease in aqueous humour VEGF concentration compared with baseline.
However, the mean VEGF concentration in the responder group at 2 months was significantly lower than that in the nonresponder group (113.7 vs 451.5 pg/mL), despite there being no significant difference between the two groups at baseline (929.2 vs 1391.4 pg/mL).
In addition, eyes that responded to anti-VEGF therapy had significant average declines from baseline to 2 months in the aqueous humour concentration of intercellular adhesion molecule-1 (1649.3 vs 1222.7 pg/mL), interleukin-10 (0.4 vs 0.2 pg/mL), monocyte chemotactic protein-1 (1582.9 vs 1355.2 pg/mL), placental growth factor (11.0 vs 4.9 pg/mL), and transforming growth factor-β2 (10,811.8 vs 9530.9 pg/mL). No such reductions were observed among the nonresponders.
Writing in the American Journal of Ophthalmology, Muni and co-authors conclude: “The use of aqueous humor cytokine concentrations for timely identification of potential poor responders to anti-VEGF therapy may enable more effective treatment regimens that improve anatomical outcomes in eyes with DME.”
By Laura Cowen
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