MSL-109 adjuvant therapy for cytomegalovirus retinitis in patients with acquired immunodeficiency syndrome: The monoclonal antibody cytomegalovirus retinitis trial

Objective: To evaluate the efficacy and safety of an intravenous human monoclonal antibody to cytomegalovirus (CMV), MSL-109, as adjuvant treatment for CMV retinitis. Methods: Two hundred nine patients with acquired immunodeficiency syndrome and active CMV retinitis were enrolled in a multicenter, phase 2/3, randomized, placebocontrolled clinical trial. Patients received adjuvant treatment with MSL-109, 60 mg intravenously every 2 weeks, or placebo. Randomization was stratified on the basis of whether patients had untreated or relapsed retinitis. Primary drug therapy for CMV retinitis was determined by the treating physician. Results: The rates of retinitis progression, as evaluated in a masked fashion, were 3.04/person- year in the MSL-109-treated group and 3.05/person-year in the placebo- treated group (P=.98; Wald test); the median times to progression were 67 days in the MSL-109-treated group and 65 days in the placebo-treated group. No differences between the 2 groups were noted in the rates of increase in retinal area involved by CMV, visual field loss, or visual acuity outcomes. The mortality rate in the MSL-109-treated group was 0.68/person-year, and in the placebo-treated group, 0.31/person-year (P=.01). The mortality difference was not explained by differences in baseline variables or in concurrent antiretroviral therapy. Among patients with newly diagnosed retinitis, mortality rates were similar (MSL-109, 0.41/person-year; placebo, 0.42/person-year; P=.95), whereas among patients with relapsed retinitis the MSL-109-treated group had a greater mortality rate (MSL-109, 0.83/person- year; placebo, 0.24/person-year; P=.003). However, the mortality rate in the placebo-treated patients with relapsed CMV retinitis was lower than that in the placebo-treated patients with newly diagnosed CMV retinitis and lower than that in other trials of patients with relapsed CMV retinitis. Conclusions: Intravenous MSL-109, 60 mg every 2 weeks, appeared to be ineffective adjuvant therapy for CMV retinitis. The mortality rate was higher in the MSL-109-treated group, but the reasons for this difference remain uncertain.