The non-toxic and biodegradable adjuvant Montanide ISA 720/CpG can replace Freund's in a cancer vaccine targeting ED-B—a prerequisite for clinical development

We have recently shown that immunization against the extra domain-B (ED-B) of fibronectin, using Freund's adjuvant, reduces tumor growth in mice by 70%. In the present study we compare the immune response generated against ED-B using the non-toxic and biodegradable adjuvant Montanide ISA 720/CpG with the response elicited by Freund's adjuvant. Montanide ISA 720/CpG induced anti-ED-B antibodies with higher avidity and less variable levels between individuals than Freund's. Moreover, the duration of the immune response was longer and the generation of anti-ED-B antibodies in naïve mice was faster, when Montanide ISA 720/CpG was used. We conclude that it is possible to replace the mineral oil based adjuvant Freund's with an adjuvant acceptable for human use, which is a prerequisite for transfer of the ED-B vaccine to the clinic.

► We compare the immune response generated against the tumor vascular antigen ED-B in the presence of the non-toxic and biodegradable adjuvant Montanide ISA 720/CpG with the response elicited in the presence of Freund's adjuvant. ► In all aspects analyzed; antibody levels, IgG subclasses, antibody avidity, kinetics and duration of the antibody response and generation of a memory response, M720/CpG proved to be at least as potent as Freund's. ► This finding is a prerequisite for transfer of the ED-B vaccine to the clinic.