Studies of the Ocular Complications of AIDS (SOCA)--HPMPC Peripheral CMV Retinitis Trial (HPCRT)

To test and evaluate the efficacy and safety of intravenous cidofovir (Vistide, previously known as HPMPC) for the treatment of retinitis.

CMV retinitis is the most common intraocular infection in patients with AIDS and is estimated to affect 35 percent to 40 percent of patients with AIDS. Untreated CMV retinitis is a progressive disorder, the end result of which is total retinal destruction and blindness. As of September 1997, drugs approved by the United States Food and Drug Administration (FDA) for the treatment of CMV retinitis were ganciclovir (Cytovene), foscarnet (Foscavir), and cidofovir (Vistide). Cidofovir has a prolonged duration of effect permitting intermittent administration. All systemically administered anti-CMV drugs are given in a similar fashion consisting of initial 2-week high-dose treatment (induction) to control the infection followed by long-term lower dose treatment (maintenance) to prevent relapse. Cidofovir is administered as an intravenous infusion once weekly for induction therapy and once every 2 weeks as maintenance therapy. The HPCRT evaluated the efficacy and safety of cidofovir therapy.

The HPCRT was a multicenter, randomized, controlled clinical trial of cidofovir for the treatment of CMV retinitis. Patients with small peripheral CMV retinitis lesions (i.e., not at risk of immediate loss of visual acuity) were randomized to immediate treatment with cidofovir or deferred therapy until the retinitis had progressed 750 µm. Patients randomized to immediate therapy received either 1) low-dose cidofovir at 5 mg/kg once weekly induction for 2 weeks, followed by 3 mg/kg once every 2 weeks for maintenance or 2) high-dose cidofovir at 5 mg/kg once weekly induction for 2 weeks followed by 5 mg/kg once every 2 weeks for maintenance. Patients whose retinitis progressed were given treatment according to best medical judgement, and those assigned to deferral were generally treated with cidofovir. Outcomes in this trial included retinitis progression, loss of retinal area, and morbidity.

Patients were age 13 years or older with diagnoses of AIDS, according to current Centers for Disease Control and Prevention (CDC) definition, and small peripheral CMV retinitis. Retinitis lesion(s) must have been confined to less than 25 percent of the total area of the retina and confined to the periphery of the retina. Peripheral lesions were those located at least 1,500 µm from the margin of the optic disc and 3,000 mm from the center of the fovea (entirely in zone 2 or 3). Patients must have had at least one lesion 750 µm or greater in size that could be photographed and the ability to read three or more lines on ETDRS chart at 1 meter (Snellen equivalent of 8/200 or greater) in at least one eye disgnosed with CMV retinitis.

No longer recruiting. Comments: Completed. Patient recruitment began in April 1994 and was completed in February 1996.

Completed, with results published. Comments: Completed.

The HPCRT demonstrated that cidofovir (HPMPC) was effective for controlling CMV retinitis. When compared with deferral of therapy, both low-dose and high-dose cidofovir significantly prolonged the time to progression and reduced the rate of loss of retinal area. The most common side effect of cidofovir was nephrotoxicity, which generally was reversible with discontinuing cidofovir therapy.