The end of the road beckons for pracinostat


Back in 2015 pracinostat’s failure in phase II wiped 70% from MEI Pharma’s valuation. So it says something for the company’s diversification strategy that yesterday's phase III blow-up with the HDAC inhibitor set the stock back only 18%. The big story for MEI nowadays is ME-401, a PI3K delta that Kyowa Kikrin paid $100m to license earlier this year, and on which topline data from a potentially registrational study called Tidal are due in the middle of 2021. Further shielding MEI from pracinostat's fallout is that the company is no longer shouldering any development spend: that falls to the private Swiss developer Helsinn, which stepped in to the project under a 2016 deal. The partners said yesterday that a phase III trial in AML was being scrapped for futility, after an interim look at the results. A phase II study in high or very high-risk myelodysplastic syndromes is ongoing, and an early cut of the trial at Asco this year made for encouraging reading, with ORR of 33% and median overall survival of 23.5 months. But pracinostat is not without toxicity, and the HDAC inhibition mechanism has never really proved itself. The end of the road is surely near.  

HDAC inhibitors: selected marketed products and late-stage projects
  Sales ($m)
Project Company 2015 2020e 2025e
Farydak Novartis 18 79 95
Istodax Bristol-Myers Squibb 49 28
Beleodaq Aurobindo Pharma 15 5
Zolinza Merck & Co 17 4 3
Phase III
Entinostat Eddingpharm
Abexinostat Xynomic Pharmaceuticals
Pracinostat MEI Pharma/Helsinn
Source: EvaluatePharma.

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