The study had been commenced in September 2011 in five European countries.
Purethal Mites is a modified aluminum hydroxide-adsorbed extract of house dust mites for subcutaneous use, to treat severe allergic respiratory diseases.
Hal Allergy CEO Harry Flore said the commencement of the trial marks a significant step in the company’s clinical development plan.
"It also stresses our commitment to meet today’s requirements for gaining registration for specific immunotherapy products," Flore added.