Preclinical experiments suggest the cancer drugs vorinostat, belinostat and panobinostat might be repurposed to treat infections caused by human papillomaviruses, or HPVs. Highly efficacious vaccines against HPV infection exist -- including the recently approved Gardasil 9, which immunizes against nine genotypes of HPV known to cause cervical, vulvar, vaginal and anal cancers. But the vaccine needs to be given before a person becomes sexually active, since it has no therapeutic efficacy against existing HPV infections.