FDA review drops a bombshell on Bayer, J&J anti-clotting drug Xarelto

The FDA dropped a bombshell on the anti-clotting drug Xarelto (rivaroxaban) this morning, noting in an agency review that Bayer ($BAYN) and Johnson & Johnson ($JNJ) had offered insufficient data on safety as well as efficacy for preventing strokes among atrial fibrillation patients, urging an advisory committee to send researchers back to the clinic for another study. In a review peppered with comments that sometimes verged on outright scorn, the FDA reviewer cited numerous reasons for a complete response letter. Just by itself, the potential for unnecessarily endangering patients offered a chilling conclusion for a drug which had been widely billed as a likely blockbuster.

In a matter of minutes shares of Bayer dropped 12%, an enormous bite for a big cap pharma company. One of the reasons for the sudden reversal is that analysts had given the drug good chances for a positive review at an upcoming advisory committee meeting. Reuters cited those feelings just days ago, noting that one of the biggest worries was whether the treatment would be relegated to a secondary position behind an anti-clotting drug from Bistol-Myers Squibb and Pfizer. But based on the review, the agency is unlikely to let Xarelto to get close to the multibillion-dollar market without a battery of additional supporting data.

"If rivaroxaban is approved," notes the review, "patients taking it might be at greater risk of harm from stroke and/or bleeding than if they were treated with warfarin (the standard drug) used skillfully. In the opinion of this reviewer, rivaroxaban should not be approved unless the sponsor submits convincing information that it is as safe and effective for its target indication as warfarin when it is used skillfully (e.g., in the subgroup of patients at centers where TTR ≥ ~67%), or that it is as safe and effective as another approved agent, such as dabigatran."

At best, the review suggests, "it seems advisable to make rivaroxaban a third-line agent, behind both warfarin and dabigatran (Pradaxa, from Boehringer Ingelhem)."

Analysts are likely to start revising their figures on the prospects for the new drugs looking to replace warfarin, a longtime standard anti-clotting therapy that presents a number of worrying risks for doctors and patients. One likely beneficiary is Eliquis (or apixaban), a new drug being advanced by Pfizer and Bristol-Myers Squibb. Investigators released upbeat safety and efficacy data just days ago.

An advisory committee review of Xarelto is coming up on Thursday.

- here's the review from the FDA