Urovant Sciences’ vibegron has hit the co-primary endpoints in a phase 3 overactive bladder trial. But with the drug failing to clearly outperform a generic used as an active control, the results leave room to doubt whether vibegron poses a big threat to Astellas’ Myrbetriq.
Vivek Ramaswamy’s Urovant chalked up the outcome as a success, arguing that vibegron could become a best-in-class therapy after it files for FDA approval early next year. Investors took a different view, sending Urovant’s stock down 17% in premarket trading amid concerns that the data is good enough for approval but too weak to stop Astellas from growing its blockbuster overactive bladder franchise.
The difference in opinion is partly a consequence of looking at different parts of the data. Urovant focused on the clear reductions in daily urge urinary incontinence episodes and micturitions over placebo.
Skeptics zeroed in on the inability of vibegron to clearly beat tolterodine, a generic treatment for the condition. The study linked vibegron to 2.0 and 1.8 improvements in incontinence and micturitions, respectively. Subjects on tolterodine achieved improvements of 1.8 and 1.6, figures close enough to raise questions about the commercial potential of vibegron.
If vibegron comes to market, it will go head to head with Astellas’ Myrbetriq. Urovant picked up vibegron from Merck as the Big Pharma retreated from urology in 2017 in a belief that the drug delivers faster relief with fewer side effects than Myrbetriq, which is hindered by a hypertension warning.
The phase 3 data contains some evidence to support those hopes. While Astellas markets Myrbetriq as being effective within eight weeks, Urovant reported statistically significant improvements over placebo at two weeks, the first time point measured. Urovant saw a bigger drop in total incontinence than was seen in Astellas’ Capricorn trial, although such cross-trial comparisons can be inaccurate.
On the safety front, Urovant didn’t include full blood pressure analysis in the top-line readout. That is the key safety factor for vibegron, and the results of a previous study run by Merck suggest that the drug may be free from the problems that blight Myrbetriq.