Before the first Human trials of TGN1412, UK Government's drugs Safety Authority was notified that there was a risk of a catastrophic reaction. The trial left six men in intensive care after they developed a severe reaction.

TeGenero, the German manufacturer of TGN1412, had in its application to the Medicines and Healthcare Products Regulatory Authority (MHRA) reported that there had been previous incidence in which similar drugs had provoked serious adverse reaction in human volunteers. Still the MHRA allowed the trial to go ahead and six men who received the drug developed a "cytokine storm".

An interim report of the inquiry issued last Wednesday said no human error had been found in the manufacture, preparation or dose of the drug. The Investigators Brochure, which summarises evidence for the study, says: "Although not to be expected after TGN1412 administration, a cytokine release syndrome or other immunological complications may occur after infusion of TGN1412".

Tests on animals had revealed no ill effects. Apparently, the MHRA felt that TeGenero's decision to administer to volunteers a 500-fold dilution of the drug provided sufficient protection.