FDA hits Sanofi's struggling Lemtrada with new safety warning over reports of stroke, artery tears

Sanofi's Lemtrada sales slid by a double-digit percentage in the third quarter. (Sanofi)

Sanofi’s Lemtrada is already struggling in a tough multiple sclerosis field, and a new FDA safety warning isn’t going to help matters.

Thursday, the agency put out a notice citing “rare but serious” cases of stroke and tears in the lining of head and neck arteries among Lemtrada patients shortly after receiving the drug. The problems, which have been reported by 13 patients worldwide since Lemtrada’s 2014 FDA approval, “can lead to permanent disability and even death,” it warned.

As a result, regulators are adding information about the risks to Lemtrada’s prescribing label, medication guide and existing black box warning, the FDA’s most serious. The med is also approved under the name Campath as a treatment for B-cell chronic lymphocytic leukemia, and Campath’s label will get an update, too.

RELATED: Can Sanofi's new long-term Lemtrada data amp up sales in a crowded MS field?

Meanwhile, the FDA is directing patients and caregivers to seek emergency treatment as soon as possible if they experience signs or symptoms of stroke or tears, which have developed within one day of Lemtrada treatment in nearly all of the affected patients. Healthcare providers should advise their patients at every Lemtrada infusion to seek immediate medical attention if they experience red flags, the FDA said.

The safety issues mark a blow to Lemtrada, which is already struggling against newer MS competition. For the third quarter, Lemtrada’s worldwide sales slid by 10.6% to €99 million, with U.S. sales tanking even harder. There, they decreased by 18.3% to €51 million, a slide Sanofi blamed on new rivals.

Roche’s Ocrevus, in particular, has shaken up the field thanks to a stellar profile. Meanwhile, more convenient oral options—including Sanofi’s own Aubagio, which posted year-over-year sales growth of 12.6% in Q3—command a good chunk of the market, too.