Travelers' diarrhea has no approved vaccine at present, so Iomai's patch-based vaccine delivery promises convenience while avoiding systemic exposure to antigens or adjuvant.
Most cases of travelers' diarrhea are caused by enterotoxigenic E. coli bacteria (ETEC), and the US Centers for Disease Control and Prevention (CDC) estimates that 20 to 50 per cent of travelers to areas where the bacteria are endemic are sickened over a one- to two-week period, harbouring a potential market for a vaccine estimated at $450m (€350m) annually.
In the Phase 1/2 clinical trial, 160 volunteers were tested weekly for immune responses to ETEC, the major cause of travelers' diarrhea.
By the second week, the fold rise in antibodies to the ETEC antigen in the dry patch groups was significantly greater for all time points compared to the liquid-based version of the vaccine.
Moreover, dry patch recipients had greater than 95 per cent seroconversion rates with one dose.
Further Phase 2 studies are ongoing and Iomai's plan is to enter Phase 3 trials in 2007.
"Iomai plans to first seek regulatory approval in the United States, though the company hopes to commercialise its products globally," Stanley Erck, the company's president and chief executive officer, told In-PharmaTechnologist.com.
"Transcutaneous immunisation (TCI) remains an experimental technology, still Iomai expects that, should they win approval, their products will be priced competitively with existing vaccines."
TCI technology uses a patch placed on the surface of the skin to deliver vaccines and adjuvants to a group of antigen-presenting cells called Langerhans, located on the skin's outermost layer, which in turn deliver the vaccines and adjuvants to the nearby lymph nodes to produce a sustained immune response.
The needle-free technology can be applied to a wide range of vaccines, so Iomai has submitted to the US Department of Health and Human Services (DHHS) a proposal to receive government funding for further development of its adjuvant skin patch for pandemic influenza.
Iomai will develop a plan to produce 150m doses of its patch in a six-month period if awarded the contract.
What makes Iomai's immunostimulant patch particularly interesting for the US government is that it can be used with any avian pandemic flu vaccine to boost supplies by up to 100-fold, allowing much smaller doses of vaccine to be administered - a 'dose-sparing' approach to vaccination.
If awarded the DHHS grant, Iomai says it is prepared to scale up production of the patches, validate its production process, and design and build a facility capable of large-scale production.