Designing Vaccines against Human Papillomavirus and Hepatitis B Virus: Similarities and Differences for Preventable Viral Infections and role of AS04 Adjuvant System in Addressing Specific Challenges

This opinion paper describes the experience of GSK Bio in developing two vaccines with a novel Adjuvant System (AS04) against two viral infections, Human papillomavirus (HPV) and Hepatitis B virus (HBV). Developing a vaccine against HPV is difficult because the virus remains local, evades the immune system, and does not induce a reliable long lasting protection upon natural infection. Vaccination of pre-haemodialysis and haemodialysis patients against hepatitis B represents a challenge as well, because these patients are immunocompromised and develop a reduced and short lasting immune response to administration of conventional HBV vaccines. Adjuvants can be used to amplify the immune response to vaccine antigens. The combination of antigens with more than one adjuvant (referred to as “Adjuvant System”), can lead to the development of vaccines which generate specific and effective immune responses adapted to both the pathogen and the target population. The Adjuvant System AS04 contained in the two licensed vaccines against HPV and HBV described here is a combination of the TLR4 agonist MPL and aluminium salt. Clinical results from these AS04 adjuvanted vaccines are described in light of other vaccines adjuvanted with aluminium salts only. The vaccines formulated with AS04 have been shown to enhance the immune responses while maintaining a clinically acceptable reactogenicity and safety profile.