New and shorter target substems were adopted in 2009. They mostly consist of a consonant, plus a vowel which is omitted if the source substem begins with a vowel. For example, human antibodies targeting the immune system receive names ending in "-lumab" instead of the old "-limumab". Some endings like "-ciximab" remain unchanged. The old system employed seven different substems for tumor targets, depending on the type of tumor. Because many antibodies are investigated for several tumor types, the new convention only has "-t(u)-".