- Are receiving medication that affects the immune system, fights HPV, or is investigational, except for anti-HIV drugs provided by coenrolling in a Phase II or III trial with approval of a study chair within 30 days of study entry, including but not limited to systemic interferons and interleukins, thalidomide, systemic cidofovir, and HPV vaccines. This study has been changed. The following medications are no longer excluded: thymopentin, hydroxyurea, granulocyte colony-stimulating factor (G-CSF and filgrastim), and GM-CSF (sargramostim).