An experimental cream containing a drug used to treat a serious eye infection in people with AIDS has shown potential as a therapy for pre-cancerous genital lesions caused by human papillomavirus (HPV), according to clinical trial results published online ahead of print by the journal AIDS.

The drug, Vistide (cidofovir), is approved an intravenous medication to treat cytomegalovirus (CMV) disease of the retina, an infection that can lead to blindness and can occur in HIV-positive people with very low CD4 cell counts. Noting that Vistide is also active against HPV, which can cause pre-cancerous lesions both in and around male and female genitalia, researchers with the AIDS Malignancy Consortium (AMC) conducted a clinical trial involving 33 HIV-positive men and women with external genital lesions treated with a topical version of the drug.

The cream was applied to lesions of the area around the anus (perianus) and/or vulva once daily for five days, followed by a nine-day break. This cycle was repeated six times.

Overall, five of the 33 (15 percent) had a complete response to treatment, 12 (36 percent) had a partial response, seven (21 percent) had stable disease and two (6 percent) had progressive disease. No comparisons to a placebo group or those receiving the approved topical treatment Aldara (imiquimod) were made in the study.

The researchers noted the mild-to-moderate pain and burning was reported by 25 study participants; ulceration was documented in 13. Though they note that Aldara has “substantial skin and mucosal toxicity that often leads to discontinuation of treatment,” a direct comparison in a clinical trial comparing it to topical Vistide will be necessary.

“We believe that our results are particularly important because treatment of extensive high-grade [lesions of the perianus and vulva] in HIV-infected patients is difficult,” the researchers conclude. “Surgical and ablative therapies are associated with significant morbidity. Often, the lesions recur and the repeat treatments cause additive morbidity. An effective topical treatment that is well tolerated has clear benefits over the current surgical options. Even though complete clearance occurred in only 15 percent, the partial response in an additional one-third of treated patients is clinically beneficial.”

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