Hu14.18K322A is a monoclonal antibody developed at St. Jude Children's Research Hospital (SJCRH) that is made to bind to cancer cells that have a molecule called GD2 on their surface. Sometimes the human body will make an antibody to the therapeutic antibody (like hu14.18K322A) that is being given for treatment. These are called human anti-human antibodies (HAHA). When testing for HAHA in a previous cohort of patients who received hu14.18K322A, it was found that some patients tested positive for high levels of an antibody before receiving hu14.18K322A or any other anti-GD2 antibody. In this study, investigators would like to know more about the nature of this pretreatment antibody, how often is it present, and if in the laboratory it increases the killing of tumor cells.

OBJECTIVES:

• To determine whether pretreatment anti-therapeutic antibodies (PATA) represent antibodies reactive against an epitope (allotypic determinant) found on the anti-GD2 antibody hu14.18K322A
• To determine if PATA increases the anti-tumor efficacy of anti-GD2 antibodies in vitro

In the proposed study, investigators will seek to determine the nature of this antibody that is being detected in the HAHA test for this group of patients, and if, in the laboratory, it increases the killing of tumor cells, accounting for the observation that some the patients who tested positive may have an improved outcome.

The study will analyze DNA from blood samples of SJCRH patients treated with hu14.18K322A anti-GD2 antibody. Serological studies and confirmatory genotyping studies will be performed in a laboratory at the University of Wisconsin.

Inclusion Criteria:

• All participants who have or will receive treatment at SJCRH with hu14.18K322A.

Exclusion Criteria:

• Those not receiving treatment at SJCRH with hu14.18K322A.

Participants will have a diagnosis within the Ewing family of tumors, melanoma, neuroblastoma, or osteosarcoma and will receive treatment with hu14.18K322A.