Recurrent Respiratory Papillomatosis (RRP) causes wart-like lesions along the throat area and can obstruct the airway or become malignant. The cause has been related to specific types of Human Papillomavirus (HPV). The purpose of the study is to assess the clinical effectiveness of a trial drug, SGN-00101, in children with RRP and also assess its safety.

Inclusion Criteria:

• Male or female between 2 and 18 yrs old, inclusive, who has documented RRP.
• Patients with documented RRP
• Subject is surgically debulked within 7 days before the first dose of SGN-00101.
• Subject has had at least 4 debulking surgeries for RRP, had no intersurgical intervals greater than 84 days during the period of the last 4 surgeries.
• Subject is free of life threatening or serious concomitant disorders other than the disease under study.
• Females of childbearing potential must have a negative pregnancy test and must be practicing an effective/appropriate method of birth control as determined by the Investigator.

Exclusion Criteria:

• Subject has disease or status that causes compromise of the immune system.
• Subject has a history of ionizing radiation therapy to the respiratory tract.
• Patient has used concomitant medications that may suppress the immune system.
• Subject has received any specific or non-specific immunotherapy intended as treatment for their RRP (i.e. mumps vaccine injected intralesionally) within 9 months prior to Week 0 of this study.
• Subject has participated in a past study with SGN-00101
• Pregnancy and lactation.