Is Actinium Really Happening?

T he most recent survey ( 1 ) related to a -radiotherapy development showed that 27 molecules labeled with 225 Ac are presently under development, among which 13 have already reached human test level. The fi rst 225 Ac-labeled molecule has entered the clinical phase III stage ( 2 ) and might reach the market by 2028. These molecules cover the most important indications that are studied with b -emitting radionuclides, but it is obvious that each single 177 Lu-labeled drug will be explored as a 225 Ac-labeled analog. Among the 35 177 Lu-labeled molecules that have already reached the clinical stage, an estimated dozen have a high chance to reach the market before 2030, not even taking into account all the generics. Actinium-labeled drugs will follow the same trend, with a delay of about 5y. A global target of half a million patients represents only 1% of the 5-y prevalence of cumulated cancers (Global Cancer Observatory; https:// gco.iarc.fr), which remains realistic in terms of share of the market compared with surgery, external radiotherapy, or chemotherapy. Evaluation of further needs is based on today ’ s average patient dose of 100 kBq/kg. At least 10 – 12 MBq at end of bombardment must be produced per dose, taking into account losses during handling and transport and labeling yields. On the basis of an average of 3 doses for a full treatment, each patient will need a total of 30 – 36 MBq of 225 Ac at end of bombardment. In other words, 3,000 GBq at end of bombardment would be suf fi cient to treat 100,000 patients each year. Industry will have to guarantee capacity for 5 – 6 times this yearly amount by 2032. Over the past few years, several large investments were