A Study of Propranolol to Treat Kaposi Sarcoma

A clinical study of propranolol for the treatment of Kaposi Sarcoma in children and adults. This study will be an open-label single armed treatment trial that will test the effectiveness and the safety of treating Kaposi Sarcoma with propranolol.

Inclusion Criteria: * Pediatric (\< 18 years) and adult (≥ 18 years) participants with biopsy-proven and measurable Kaposi Sarcoma (KS) as defined in the KS Manual of Procedures (MOP). * No urgent clinical indication for immediate cytotoxic chemotherapy. Participants who have received cytotoxic chemotherapy \> 4 weeks prior to screening are eligible. * KS stage: * \< 18 years: * 1A (Mild): disease limited to skin, flat oral mucosal lesions, and/or flesh colored subcutaneous nodules, total \ 70% * ≥ 18 years: * Easter Cooperative Oncology Group (ECOG) performance status ≤ 2 * Participants must have adequate organ function, as defined by the following: * Bilirubin (direct or total) within normal range, or total bilirubin \ 100 × 109/L; * ANC \> 1000 cells/mm3 * Human Immunodeficiency Virus (HIV) positive participants must be on antiretroviral therapy (ART) that conforms to local standards of care. Participants will have been on ART for at least 12 weeks. Participants will not be excluded based on CD4 count or HIV viral load. * HIV positive participants must not show recent improvement on ART that may confound response evaluation: * If on ART 12 to 24 weeks, participants must show evidence of KS progression requiring further systemic treatment. * If on ART for \>24 weeks, must show no evidence of regression in the last eight weeks. * HIV-negative participants must not show evidence of improvement in the three months prior to enrollment. * No history of asthma or diabetes mellitus (as it is a risk factor for hypoglycemia). * No clinically significant cardiovascular disease other than hypertension, which is permitted. * No use of beta-adrenergic antagonists for other indications. * Not pregnant or planning to become pregnant. Propranolol is United Stats Food and Drug Administration (US FDA) pregnancy category C. At this time, the study team has determined that the unknown risk to a developing fetus is greater than the potential benefit of treatment. * Use of effective contraception for women of childbearing potential, defined as a sexually mature woman who: 1) has not undergone a hysterectomy or bilateral oophorectomy; or 2) has not been naturally postmenopausal for at least 24 consecutive months. * Women of child bearing potential (WOCBP) must agree to use adequate contraception (oral contraceptive pills, intrauterine device, Nexplanon, Depo-Provera, or permanent sterilization, etc., or another acceptable method as determined by the investigator) prior to study entry, for the duration of study participation. * Not breast feeding. Exclusion Criteria: • Participants who do not fulfill the criteria as listed in Section 3.1 above, are ineligible. Additionally, the presence of any of the following conditions will exclude a participant from study enrollment: * Children and adolescents with lymph node or visceral disease, woody edema, or ≥ 20 cutaneous lesions. * Children and adolescents with heart rate or systolic blood pressure \