TeGenero, the German biotechnology company whose experimental drug caused the hospitalisation of six men earlier this week, has apologised to the victims and their families and confirmed that all testing of the antibody has ceased.

Two of the men remain in a critical condition after experiencing multiple organ failure after taking the antibody – TGN1412 – in a Phase I clinical trial run by Parexel. The remaining four are also seriously ill.

Parexel said yesterday that the clinical trial at Northwick Park Hospital in North London was the first time that TGN1412 had been given to humans. The UK Medicines and Healthcare products Regulatory Agency (MHRA) and the police are investigating the trial, but analysts suggested that – at the moment – there is nothing to suggest this was anything other than an unexpected and tragic side effect that appeared in humans but not laboratory animals.

“These events were completely unexpected and do not reflect the results from initial laboratory studies which enabled us to progress investigations into human volunteers”, commented Dr Benedikte Hatz, TeGenero’s chief executive. “The clinical trial performed by Parexel adhered to standard clinical research guidelines,” he stressed.

TGN1412 is a humanised agonistic anti-CD28 monoclonal antibody that was being developed for the treatment of immunological diseases and leukaemia.