Human papilloma virus (HPV) causes anal lesions, which are common among positive men and women. Unlike less threatening anal warts, lesions can turn cancerous. And treating the pesky, hard-to-see (and -feel) growths can be a literal pain in the ass; current options include burning, cutting or freezing. But an experimental vaccine may soon put those painful therapy choices behind us.

Don’t confuse this therapeutic vaccine, dubbed HspE7, with Gardasil, the preventive HPV vax approved in June. Joel Palefsky, MD, a longtime HPV expert at the University of California at San Francisco, says Gardasil stimulates antibodies to prevent HPV from entering skin cells, while HspE7 has a therapeutic edge because it “works by stimulating an immune response to remove cells already infected with HPV.”

Palefsky conducted a recent study that showed that HspE7 (three injections into the thigh over eight weeks) was safe in 15 HIV positive men and women with high-grade anal lesions. Moreover, in four cases, the lesions became less severe; in another, they disappeared. He calls the data encouraging but adds that only larger studies will establish the vaccine’s usefulness. If tests go well, HspE7 could be ready for approval in a few years.

Men and women should make sure to get annual Pap smears to check for HPV anal lesions and treat any high-grade versions that show up. This is not something to sit on.