Pfizer doubles down in prostate cancer

Pfizer, already looking on shaky ground with mevrometostat in prostate cancer, has just started a first-line phase 3 trial of this EZH2 inhibitor in this tumour, adding to its recently begun second-line study. The new Mevpro-2 trial is enrolling treatment-naive metastatic castrate-resistant prostate cancer patients (previous therapy in the castration-sensitive setting, with first-generation anti-androgen agents or docetaxel, is allowed). Mevrometostat plus Xtandi will be compared versus Xtandi alone; the primary endpoint is radiographic PFS. The trial comes soon after the start of Mevpro-1, testing mevrometostat plus Xtandi in patients previously treated with Zytiga. However, Pfizer’s haste looks questionable after the recent failure of Ipsen’s similarly acting Tazverik in post-Zytiga prostate cancer, with rPFS results numerically similar to what Pfizer saw with mevrometostat in phase 1. Other EZH2 blockers have also fallen short in prostate cancer, and there isn’t much competition in this space. One rival is Oric Pharmaceuticals, whose ORIC-944 is designed to hit EED, one subunit of the enzyme complex PRC2 – another being EZH2. Oric has claimed that its project could have an edge over EZH2 inhibitors, and says pivotal development of ORIC-944 could start in 2025.

Projects hitting PRC2 subunits active in prostate cancer

Source: OncologyPipeline.