The battle’s on. And let the marketing campaigns and medical sniping begin.
GlaxoSmithKline said today that the results of a comparative HPV vaccine study it had sponsored showed that Cervarix generated between two and six times as many antibodies as Gardasil.
Both vaccines utilize novel “virus-like particles,” VLPs. These are created by inserting DNA into yeast cells to make a genetically-engineered ‘seed stock’. The resulting paste is cultured in a fermenter to increase cell mass and then incubated; eventually the antigen VLPs are filtered from the paste and blended with adjuvants. The paste is then cleaned and reused.
Both vaccines protect against HPV strains 16 and 18, thought to be responsible for 66 to 70 percent of cervical cancers, although one study recently showed 16 to have been losing ground to strains other than 18 (there are believed to be up to 120 strains of HPV) for some years. Gardasil also protects against two wart-causing strains.
But Cervarix also uses a novel adjuvant containing aluminium salt and monophosphoryl lipid A (MPL), and according to GSK that makes a big difference in antibody levels—a claim that made a Merck spokesman sniff disparagingly, “It's disease efficacy that's really the most important, and we certainly have very high efficacy against some very important disease endpoints."
Cervarix has been used in the EU for some time and was chosen over Gardasil by Britain for its country-wide vaccination program. However, the FDA is currently looking it over for approval in the US, where Merck has had the market to itself up until now.
Both vaccines have been associated with side-effects including paralysis, convulsions and immune disorders, although no causal link has been proven and the CDC beleives that HPV vaccines are safe.
Approval for Cervarix in the US could come by the fall—so if you think the Gardasil campaign up to now has been aggressive, honey, you ain’t seen nothin’ yet.