Nelfinavir Mesylate in Treating Patients With Kaposi Sarcoma

Inclusion Criteria: * Biopsy-proven KS involving skin (with or without visceral involvement) without need for urgent cytotoxic therapy; there should be no evidence of improvement in KS in the 4 weeks immediately prior to study enrollment * Known human immunodeficiency virus (HIV)-1 infection status, as documented by any nationally approved, licensed HIV rapid test performed in conjunction with screening (or enzyme-linked immunosorbent assay \[ELISA\], test kit, and confirmed by approved test at each study site; United States (U.S.) participants only: alternatively, this documentation may include a record demonstrating that another physician has documented the participant's HIV status based on either: * Approved diagnostic tests, or * The referring physician's written record that HIV infection was documented, with supporting information on the participant's relevant medical history and/or current management of HIV infection * Participants enrolled outside the U.S. must have a confirmatory diagnostic test sequence as appropriate per national standards, detailed as above, performed regardless of prior documented HIV status; for HIV-negative participants, testing must be performed no more than 1 month prior to study enrollment; NOTE: the term "licensed" refers to a U.S. Food and Drug Administration (FDA)-approved kit or for sites located in countries other than the United States, a kit that has been certified or licensed by an oversight body within that country and val…