Adjuvant for HPV Vaccine Enhances Immune Response Levels

Researchers from GlaxoSmithKline (GSK, Rixensart, Belgium, www.gsk.com) have shown that an investigational human papillomavirus (HPV) types 16 and 18 L1 vaccine formulated with a novel adjuvant can induce immune response levels that are higher in magnitude and persistence than formulations containing aluminum salt alone.

The adjuvant, AS04, is composed of aluminum salt and 3-deacylated monophosphoryl lipid A. HPV is the leading cause of cervical cancer, the second most common cancer in women worldwide. To provide long-term protection against HPV types 16 and 18, an effective virus-like particle (VLP)-based prophylactic vaccine must be formulated to induce a strong humoral and cellular immune response that persists for several years.

GSK researchers first conducted an in vitro study in culture cells (the human monocyte cell line U937 incubated with AS04). Results demonstrated AS04 was “associated with substantial and greater induction of TNFalpha production compared with aluminum salt alone.” (Tumor Necrosis Factor-alpha, or TNFalpha, is the key mediator of immunologic functions). Two other assessments involving vaccinations of human subjects showed that the investigational cervical cancer vaccine formulated with AS04 induced “substantially higher” levels of anti-VLP16 and 18 antibodies than formulations of aluminum salt only. Furthermore, the higher antibody responses associated with the AS04 formulation persisted for as long as 3.5 years postvaccination in human subjects.