Longitudinal serum auto-antibody response during HER2-CAR T cell therapy in a child with rhabdomyosarcoma identified using Protein microarray

Protein microarray was used to identify proteins with elevated interactions with serum autoantibodies in a responding patient with rhabdomyosarcoma before and after multiple doses of HER2 CAR T cell therapy. Elevated signals were observed for multiple proteins interacting with serum autoantibodies following multiple doses of HER2-CAR T cell treatment when compared to pre-treatment serum. Serum samples were obtained before start of treatment and subsequent follow up time points after treatment from a child with metastatic rhabdomyosarcoma enrolled in a phase 1 clinical study testing safety of HER2 targeted Chimeric Antigen Receptor (CAR) modified T cells according to Baylor College of medicine IRB approved study protocol H-24489 with the clinical trial registry number NCT00902044. The serum samples (n=6) were probed utilizing one ProtoArray™ Human Protein Microarray per sample along with a negative control.