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Lemtrada Lawsuits

Lawyers are accepting cases on behalf of multiple sclerosis patients injured by Sanofi Genzyme’s drug Lemtrada (alemtuzumab). Patients who suffered ischemic stroke, hemorrhagic stroke, or head or neck arterial dissection within three days of receiving a Lemtrada infusion may be entitled to compensation. People whose loved ones died after being treated with the medication may also qualify for a lawsuit.

More than 21,000 patients worldwide had received Lemtrada treatment as of October 2018, according to a Sanofi Genzyme press release. These people may have been at risk of rare strokes and tears in the walls of blood vessels in the head or neck, known as cervicocephalic arterial dissection.

Sanofi Genzyme began marketing Lemtrada for relapsing multiple sclerosis in 2014, but a warning for the risk of stroke or arterial dissection did not appear in United States prescribing information until November 2018.

According to lawyers, MS patients who suffered these complications may be entitled to compensation for medical expenses, pain and suffering, and lost wages.

FDA Warning for Stroke and Arterial Dissection

While Lemtrada can cause a number of side effects, ischemic stroke, hemorrhagic stroke, head or neck arterial dissection and death are the main injuries claimed in lawsuits.

In November 2018, the Food and Drug Administration warned about rare but serious risks of stroke and blood vessel wall tears with alemtuzumab.

According to the FDA’s safety announcement, most of the patients who experienced stroke or arterial dissection developed symptoms within one day of receiving the drug. In one case, symptoms started three days after treatment.

Lemtrada stroke illustration
Stroke and dissection injuries reported to the FDA occurred within three days of taking Lemtrada. Source: FDA

A June 2019 search of the FDA Adverse Events Reporting System (FAERS) Public Dashboard showed nine cases of ischemic and hemorrhagic stroke reported between 2017 and March 31, 2019. The FDA also received seven reports of artery dissection, carotid artery dissection and vertebral artery dissection. Two cases were fatal. Six people were hospitalized, and two were disabled.

An accurate number of people who actually suffered these problems is difficult to obtain because FAERS data is submitted voluntarily.

Accusations Against Sanofi Genzyme

Lemtrada lawsuits are in the early stages, and lawyers are still gathering cases to file. There have not been any trials or publicized settlements. Drug lawsuits like these often proceed on the premise that the drug company should have warned about a certain drug risk but failed to do so.

In this case, Sanofi Genzyme failed to warn the public that its drug could cause strokes and tears in the arteries. If doctors and patients had known, they may have chosen another treatment option and avoided serious injury.

Other accusations made in lawsuits against Sanofi may include:
  • Aggressive and illegal marketing of Lemtrada
  • Breach of its duty of care by not warning about risks
  • Conscious disregard or indifference to the life, safety or rights of people injured by Lemtrada
  • Fraud and negligence
  • Intentionally failing to warn about Lemtrada’s risks for the sake of profit
  • Reckless conduct

Class Action Says Sanofi Misrepresented Drug’s Safety and Efficacy

The latest rash of Lemtrada lawsuits is not the first. In 2013, investors filed a class action lawsuit against Sanofi Genzyme for misrepresenting the safety and efficacy of the drug.

According to Solak v. Sanofi et al., “Sanofi (and Genzyme as its subsidiary) strongly touted the efficacy and safety of Lemtrada, by directing investors’ attention to two pivotal studies which the Company claimed demonstrated the safety and efficacy of Lemtrada.”

However, the FDA Advisory Committee on Peripheral and Central Nervous System Drugs found that “significant concerns exist regarding the safety profile of alemtuzumab [Lemtrada] and the adequacy of the efficacy data.”

The lawsuit, which was filed in the United States District Court Southern District of New York, claimed Sanofi also misled investors regarding the design of clinical trials for the drug. Sanofi did not disclose “trials contained high levels of placebo effect and observer bias,” which affected the FDA’s decision to approve the drug.

Three doctors on the FDA approval panel found numerous issues with the data submitted by Sanofi, according to the lawsuit.
Dr. Mentari
found numerous serious and potentially fatal safety concerns and could not recommend approval of the drug without proof of substantial clinical benefit.
Dr. Marler
found Sanofi did not submit enough evidence to support Lemtrada’s effectiveness.
Dr. Yan
found the design of the trials was “troublesome” and Sanofi did not provide evidence from adequate and well-controlled studies of the drug’s effectiveness in multiple sclerosis.
Lemtrada Lawsuit Facts
  1. Injuries Ischemic stroke, hemorrhagic stroke, head or neck (cervicocephalic) arterial dissection, or death
  2. Manufacturer Sanofi Genzyme
  3. Main Reason for Suing Sanofi Genzyme failed to warn about the risk of stroke and arterial dissection.

Please seek the advice of a medical professional before making health care decisions.

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Michelle Llamas, Senior Content Writer
Written By Michelle Llamas Senior Writer

Michelle Llamas has been writing articles and producing podcasts about drugs, medical devices and the FDA for seven years. She specializes in fluoroquinolone antibiotics and products that affect women’s health such as Essure birth control, transvaginal mesh and talcum powder. Michelle collaborates with experts, including board-certified doctors, patients and advocates, to provide trusted health information to the public. Some of her qualifications include:

  • American Medical Writers Association (AMWA) Engage Committee and Membership Committee member
  • Centers for Disease Control and Prevention (CDC) Health Literacy certificates
  • Original works published or cited in The Lancet, British Journal of Clinical Pharmacology and the Journal for Palliative Medicine
Edited By
Emily Miller
Emily Miller Managing Editor

5 Cited Research Articles writers follow rigorous sourcing guidelines and cite only trustworthy sources of information, including peer-reviewed journals, court records, academic organizations, highly regarded nonprofit organizations, government reports and interviews with qualified experts. Review our editorial policy to learn more about our process for producing accurate, current and balanced content.

  1. DailyMed. (2019, January 22). LEMTRADA- alemtuzumab injection, solution, concentrate. Retrieved from
  2. Sanofi Genzyme. (2018, October 10). Sanofi Presents 8-Year Data on Lemtrada (Alemtuzumab). Retrieved from
  3. Solak v. Sanofi et al. (2013, December 11). Class Action Complaint for Violations of the Federal Securities Law. Case No. 1:13-CV-08806. Retrieved from
  4. U.S. Food and Drug Administration (n.d.). FDA Adverse Event Reporting System (FAERS) Public Dashboard. Retrieved from
  5. U.S. Food and Drug Administration. (2018, November 29). FDA warns about rare but serious risks of stroke and blood vessel wall tears with multiple sclerosis drug Lemtrada (alemtuzumab). Retrieved from
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