Systemic and Topical Antivirals for Control of Cytomegalovirus Anterior Uveitis: Treatment Outcomes (STACCATO)

Description

Recurrent anterior uveitis in immunocompetent individuals can be caused by multiple members of the herpes virus group, including cytomegalovirus (CMV). Repeated bouts of CMV intraocular inflammation can be associated with ocular hypertension, glaucoma, pain, vision reduction or blindness. CMV anterior uveitis is commonly misdiagnosed as a non-infectious anterior uveitis and treated as such, which can beget further complications. Diagnosis requires directed polymerase chain reaction (PCR) testing. While antiviral therapy exists for CMV, identifying the appropriate therapy has been challenging because no randomized trials comparing routes of therapy (particularly oral or topical) have been performed. Currently, CMV anterior uveitis is typically treated with oral valganciclovir in the United States but carries the risk of serious systemic side effects that necessitate laboratory monitoring. There is evidence that suggests topical ganciclovir can be used to treat and prevent recurrences of CMV anterior uveitis, though the appropriate concentration is not well defined. Topical ganciclovir is attractive because it does not require laboratory monitoring, though a unique side effect profile that includes corneal epitheliopathy and conjunctivitis may preclude long-term use. While anterior chamber paracentesis with polymerase chain reaction (PCR) testing demonstrates CMV during an initial flare of inflammation, it is unknown whether repeated recurrences of inflammation are mediated by viral re-infection and replication in the anterior chamber or if a sterile immune response is at play. Consequently, patients may be submitted to many years of oral or topical antiviral therapy. This strategy poses challenges without proper evaluation of the multiple treatment and long-term management approaches. Further studies are needed to elucidate the most appropriate antiviral therapies that balance efficacy and toxicity while treating CMV anterior uveitis.

There are no studies comparing antivirals for the treatment of CMV anterior uveitis. However, multiple studies have utilized PCR to obtain an initial viral load before treating CMV anterior uveitis. The collective initial CMV viral load from these prior studies (39 patients in total) was approximately 600,000 IU/ml. There was minimal variation within studies in terms of initial viral load, but large variation between studies. To control for variability that can arise from different assays used or assays performed at different centers, we will perform all quantitative PCR at the same United States location. Even fewer studies have documented post-treatment viral loads. Many of the post-treatment PCR values showed undetectable viral loads, making it difficult to estimate viral load reduction trends between treatment groups. Of note, the limited data demonstrated that both intravenous ganciclovir and topical ganciclovir 2% groups showed significant and rapid reductions in viral load, almost always resulting in undetectable levels by 12 weeks, and occasionally as rapidly as 2-3 weeks. We identified three patients from the literature with CMV anterior uveitis that had detectable PCR values during the course of treatment. These patients had a 95% average reduction in viral load 14 days after treatment.

We are proposing a double-masked randomized controlled clinical trial comparing the efficacy of oral valganciclovir, topical ganciclovir 2%, and placebo for the treatment of PCR-proven CMV anterior uveitis. The primary outcome will be percent reduction in viral load. We hypothesize that the oral valganciclovir arm will experience the greatest reduction in viral load. Secondary outcomes will include time to clinical quiescence and the effect of pre-enrollment topical corticosteroid use on initial viral load.

This pilot study will provide valuable information concerning the treatment of CMV anterior uveitis with oral and topical medications, including effective concentrations and side-effect profile. The information obtained from this study will help inform future larger clinical trials in CMV anterior uveitis.

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