Astellas pays $175m for a cautious Xtandi insurance plan

Astellas is clearly thinking about the looming 2027 US patent expiry of its Pfizer-partnered prostate cancer blockbuster Xtandi, yesterday paying $175m to acquire the private group Propella Therapeutics. Propella’s lead is abiraterone decanoate, a prodrug of Johnson & Johnson’s now off-patent Zytiga. Xtandi and Zytiga alike are novel androgen-directed drugs, though they act in different ways, and they have transformed the front-line treatment of metastatic castration-resistant prostate cancer. Very little is known about abiraterone decanoate, however; the project has been in phase 1 since 2021, though the only clinical data, presented at ESMO last year and at ASCO-GU in February, concern PSA responses and a safety profile suggesting that intramuscular abiraterone decanoate has a better therapeutic index than the orally dosed Zytiga. Any doubts about the logic of the Propella deal have to be viewed in light of the fact that $175m is a small outlay for Astellas.