Another clinical trial had been testing a humanized anti-GD2 antibody linked to IL-2 (Hu14.18-IL2) in relapsed or refractory neuroblastoma and OS, administered along with NK cells activated and expanded ex vivo by K562mbIL15-41BBL, but the study was recently withdrawn because of “limited resources due to COVID-19” (NCT03209869). Here, IL2 is linked to neuroblastoma.