Was amorphous aluminium hydroxyphosphate sulfate adequately evaluated before authorisation in Europe?

Abstract

The Merck Sharp & Dohme Corp aluminium adjuvant ‘amorphous aluminium hydroxyphosphate sulfate’ (AAHS), primarily used in the Gardasil vaccines against human papilloma virus, has been criticised for lack of evidence for its safety. Documentation from Danish authorities and answers from the European Medicines Agency (EMA) suggest that AAHS may not have been sufficiently evaluated. Documentation from the Danish Medicines Agency shows discrepancies in the trial documents of two prelicensure clinical trials with Gardasil in 2002 and 2003. For both trials, the Agency seems to have authorised potassium aluminium sulfate as the adjuvant and not AAHS. In addition, the participants in the trial launched in 2002 were informed that the comparator was saline, even though the comparator was AAHS in an expedient consisting of L-histidine, polysorbate-80, sodium borate and sodium chloride. According to the EMA, AAHS was first introduced in Europe in 2004 as the adjuvant in Procomvax, a vaccine against the hepatitis B virus and Haemophilus influenza type b. The EMA reports that AAHS was introduced without any prelicensure safety evaluation. The adjuvant is described by the company to be both physically and functionally distinct from all other previously used aluminium adjuvants. There is a need for rigorous evaluation of benefits and harms of the adjuvant AAHS.