Abstract
Purpose :
Interleukin 6 (IL-6) is a proinflammatory cytokine implicated in the pathogenesis of various intraocular vascular diseases. The objectives of this study were to measure and compare IL-6 levels of patients enrolled in the HARBOR trial of ranibizumab (RBZ) in nAMD, and to describe the vision outcomes with RBZ in the patients with IL-6 data.
Methods :
This retrospective analysis of the phase 3 HARBOR study (NCT00891735) included patients who had matching aqueous humor and serum samples collected at month 2 of study. IL-6 levels were measured using a proprietary multiplex chip technology and IL-6 distribution in aqueous vs. serum at month 2 were compared using the Wilcoxon rank-sum test. Since aqueous and serum samples were collected after the third dose of RBZ at month 2, Early Treatment Diabetic Retinopathy Study (ETDRS) letter score at month 2 was used as the baseline to calculate best-corrected visual acuity (BCVA) change for each patient over the course of the study. Mean BCVA change from month 2 was compared for groups of patients stratified by their aqueous IL-6 levels.
Results :
In total, 36 patients had matching aqueous and serum samples (all white and 61% female) with fewer classic lesions compared with the overall HARBOR population (6% vs. 16%). Median IL-6 levels were higher in the aqueous humor compared with serum [6 pg/mL (range <1 to 55.7) vs. 3.5 pg/mL (range <1 to 19.1); P=0.005]. Patients with aqueous IL-6 ≥15 pg/mL (n=9) on average lost 9 letters at month 24 while patients with IL-6 <15 pg/mL (n=27) gained 2.9 letters. These findings were consistent across a range of cutoffs for IL-6 (6 to 15 pg/mL). Differences in vision outcomes are descriptive and did not reach statistical significance.
Conclusions :
The results from this HARBOR substudy suggest that in patients with nAMD, aqueous IL-6 levels are higher and exhibit a broader distribution compared to serum levels, which may allow patient stratification. There was no correlation between aqueous and serum IL-6 levels. These results should be interpreted with caution due to the small number of patients and the post hoc nature of the analysis.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.