1219P - Maternal immunization against ALK as a weapon to fight neuroblastoma

Abstract

BackgroundNeuroblastoma (NB) is the most common extracranial solid tumor in infancy. Some germline and somatic mutations associated with NB have been identified as activating mutations of the anaplastic lymphoma kinase (ALK) oncogene. Because of the nature of NB, which can occur in the early post-natal life or even during fetal life, we evaluated the efficacy of a DNA vaccine against ALK in a spontaneous preclinical model of NB, harboring ALKF1174L mutation in association with MYCN amplification (ALKF1174L/MYCN mice) by means of maternal immunization (MI). MethodsMYCN transgenic females were immunized against ALK by DNA vaccination by using a plasmid coding for the extracellular and trans-membrane domains of human ALK (ALK-ECTM) followed by electroporation, and then they were mated with an ALKF1174L-transgenic male. In ALKF1174L/MYCN offspring, the presence of abdominal, cervical and paraspinal tumors has been evaluated and quantified by Magnetic Resonance Imaging. The humoral immune response induced against ALK in the mothers and their offspring, as well as the presence of immune-complexes containing ALK, have been evaluated by ELISA. ALK expression in tumor tissue was assessed by Western blot. ResultsPre-birth immunization against ALK leads to an extended survival time and to a lower tumor growth kinetic in ALKF1174L/MYCN offspring born from ALK-ECTM-vaccinated mothers (ALK-ECTM offspring) as compared to controls born from control empty vector-vaccinated mothers. Maternally derived anti-ALK antibodies were successfully transferred from mothers to newborns. Moreover, anti-ALK IgM were found in the sera of five- and six-week old ALK-ECTM offspring, suggesting the induction of the pups’ own immune response against ALK. This effect could be due to the breast milk-mediated transfer of immune-complexes containing ALK, found in the milk of vaccinated mothers and in their offspring sera. Finally, MI against ALK induces a decrease in ALK expression in ALK-ECTM offspring’ tumor tissue. ConclusionsOverall, these results indicate that MI against ALK induces an active immunization against this oncoantigen in the offspring, impairing tumor development and enhancing survival time in a preclinical model of NB. Legal entity responsible for the studyDepartment of Molecular Biotechnology and Health Sciences. FundingAssociazione Italiana per la ricerca sul Cancro. DisclosureAll authors have declared no conflicts of interest.