Biotech Values

[DewDiligence]

Bayer reports Xarelto subgroup data from ROCKET-AF study for patients who had a prior stroke/TIA (the “secondary-prevention” indication):

http://www.press.bayer.com/baynews/baynews.nsf/id/Major-Subgroup-Analysis-Shows-Bayers-Rivaroxaban-Highly-Effective-Prevention-Recurrent-Strokes?Open&ccm=001

The secondary prevention subgroup of the ROCKET AF study, consisting of patients with a prior history of stroke or TIA (representing 55 per cent of the total study population), received either 20mg once daily rivaroxaban (or 15 mg for patients with moderate renal impairment), or dose-adjusted warfarin. The ROCKET AF principal safety outcome was major and non-major clinically relevant bleeding. Rivaroxaban showed a numerically lower (13%) risk compared to warfarin in the prevention of recurrent strokes or non-CNS embolism in the safety population while on-treatment (2.26 events per 100 patient-years for rivaroxaban and 2.60 events per 100 patient-years for warfarin, HR 0.87, 95% CI [0.69, 1.10]).

In other words, Xarelto was better than warfarin in stroke (or non-CNS embolism) prevention, but the 13% reduction in risk was not statsig. The reduction in risk would have had to be in the high teens (HR in the low 80s) for this comparison to have been statisg.

What about bleeding?

Similar rates of overall bleeding to those seen in the primary ROCKET AF analysis were found, with no difference between the treatment groups (13.31 safety outcome-related events per 100 patient-years for rivaroxaban and 13.87 events per 100 patient-years for warfarin, HR 0.96, 95% CI [0.87, 1.07]).

In other words, Xarelto’s bleeding rate was lower than warfarin’s by 4%, which was not close to being statisg. Bleeding rates in both arms of the prior-stroke subgroup were similar to those in the overall trial.

What about intracranial hemorrhage (the scariest form of bleeding)?

Rates of ICH were numerically lower in the rivaroxaban arm (0.59 events per 100 patient-years for rivaroxaban and 0.8 events per 100 patient-years for warfarin, HR 0.74, 95% CI [0.47, 1.15]).

In other words, Xarelto’s ICH rate was 26% lower than warfarin’s, but the number of events was too small for this comparison to be statisg.

All told, these Xarelto subgroup results are impressive, IMO, despite the fact that they are PP rather than ITT data. The subgroup data are consistent with the outcome in the trial as a whole, which found Xarelto non-inferior to warfarin on an ITT basis and superior to warfarin on a PP basis in stroke prevention, without a significant increase in bleeding (#msg-56712414).