The European Medicines Agency has issued an alert concerning vials of Roche's blockbuster breast cancer drug Herceptin which have been stolen and tampered with.

The agency notes that the vials of Herceptin (trastuzumab), thought to have been stolen in Italy, have been tampered with and "re-introduced under false credentials into the supply chain in some countries". Counterfeits have been identified in the UK, Finland and Germany, Roche said, noting that analysis of one of the vials showed that it did not contain the active ingredient.

Although only a small number of vials is thought to be affected, as a precautionary measure Roche is recalling those suspected of having being falsified. The Swiss major noted that "we understand the concern this information may cause patients and are committed to doing all we can to support the health authorities and law enforcement agencies in combating this illegal activity".

Police in Italy are investigating the theft and are looking at whether other medicines may also be affected.The EMA stressed that no affected product has so far been identified at hospital level, there are no reports that any harm has come to patients in relation to the falsified medicine. Nevertheless, healthcare professionals across the European Union are being provided with information on signs seen so far that may indicate a vial is not genuine.

These include batch numbers and expiry dates on most vials that do not match the package and also there is liquid present in some powders for solution; Herceptin is a white to yellow powder. The EMA also called for vigilance concerning evidence of tampering with rubber stoppers, crimping caps or lids.