Recombinant Glycosylated Human Interleukin-7 (CYT107) for the Treatment of Kaposi Sarcoma in Participants With HIV and Immune Non-Response (REGIMENKS HIV)

Background: Kaposi sarcoma (KS) is a cancer that causes abnormal tissue to grow in the skin, lymph nodes, and other organs. KS is caused by a virus known as Kaposi sarcoma herpesvirus. People infected with human immunodeficiency virus (HIV) account for 80% of KS cases in the United States. Having HIV can weaken the immune system and this can lead to KS. Weaker immune systems may be measured by low T cells (a type of immune cell). CYT107 is a human protein, made in a laboratory, that may help boost immunity, specifically by increasing T cells, in people with HIV-associated KS. Objective: To see if CYT107 can shrink KS tumors. Eligibility: People aged 18 years and older with HIV-associated KS. Design: Participants will be screened. They will have a physical exam with blood tests. Their skin lesions will be measured. They will have an x-ray of their lungs. Their ability to perform everyday tasks will be reviewed. A sample of lesion tissue (biopsy) may be collected from the skin. CYT107 is injected into the muscle of the arm, buttocks, or lower thigh once a week for up to 4 weeks. Participants will receive the shots at the clinic. Blood and other tests will be repeated at each visit. KS lesions will be measured and photographed on the 1st and 4th visits. Participants who improved after the first 4 weeks may have another 4-week treatment within a year. Follow-up visits will continue for 3 years.

* INCLUSION CRITERIA: * Histologically confirmed KS by NCI Laboratory of Pathology (LP), with or without any prior systemic KS treatment * Participants with HIV infection * Age \>= 18 years * All participants should have at least five (5) measurable cutaneous KS lesions with no previous local radiation, surgical or intralesional cytotoxic therapy that would prevent response assessment for that lesion. * Participants with stage T1 KS with visceral involvement must: * have any/all associated tumor associated symptoms \= 8g/dL * total bilirubin \