Objective:
Retinal vein occlusions (RVO) are significant sources of vision loss, affecting mostly healthy people over 55 years of age. The common source of vision loss is the macular edema accompanying the retinal injury. Very recently, studies employing monthly anti-vascular endothelial growth factor (VEGF) treatments have demonstrated a benefit to this line of treatment; however, the duration of effectiveness appears to be short lived and the length of time needed for these monthly injections remains unknown. A histologic study of human retinas with RVOs found the presence of activated microglia. Microglia are capable of migrating through the retina to sites of inflammation to associate closely with neurons and the vasculature, and are key cellular players in the mediation of processes of chronic inflammation. For these reasons, microglia represent a promising cellular target for forms of therapy that limit the deleterious inflammatory changes found in vein occlusions. Minocycline, a second-generation tetracycline, has been shown to exhibit anti-inflammatory properties, including microglia inhibition. The objective of this study is to investigate the safety and efficacy of minocycline as a microglia inhibitor in participants with branch retinal vein occlusion (BRVO).
Study Population:
A minimum of ten and a maximum of 20 participants who meet the eligibility criteria may be enrolled. Eligibility criteria include: foveal center-involved macular edema secondary to a BRVO, retinal thickness in the central subfield greater than 350 microns as measured by optical coherence tomography (OCT) and visual acuity (VA) between 20/32 and 20/200 in the study eye.
Design:
In this pilot, double-masked, randomized, multi- center study, participants will receive monthly bevacizumab injections for the first three months, followed by PRN dosing. In addition, participants will take an oral dose of 100 mg of minocycline or placebo twice daily for 24 months. During each monthly visit, participants will have their visual acuity measured and will undergo OCT testing to measure retinal thickness. At the Month 3 visit and thereafter, participants will be evaluated for "improvement" and "worsening" and will be eligible for additional bevacizumab treatment and/or investigational product (IP) depending on which criteria they fulfill. Additionally, at Month 12, participants will also be evaluated for no improvement.
Outcome Measures:
The primary outcome is the difference in mean change in best-corrected visual acuity (BCVA), as measured in ETDRS letters, between the minocycline and placebo groups in the study eye at 12 months compared to baseline. Secondary outcomes include the difference between the minocycline and placebo groups in the number of intravitreal bevacizumab injections between 12 and 24 months and baseline, changes in mean macular sensitivity as measured by microperimetry at 3, 6, 12, 18 and 24 months compared to baseline, the mean change in BCVA at 24 months compared to baseline, the changes in retinal thickness as measured by OCT at 6, 12, 18 and 24 months compared to baseline, number of participants improving greater than or equal to 1 logOCT scale step at 12 and 24 months compared to baseline, as well as changes in fluid leakage in the macula as demonstrated by fluorescein angiography at 12 and 24 months compared to baseline. Safety outcomes include the number of participant withdrawals, the number and severity of systemic and ocular toxicities and the number of adverse events.