Eisai Global Data Breach Investigation

Turke & Strauss LLP, a leading data breach law firm, is investigating Eisai Inc. regarding its recent data breach. The Eisai data breach involved sensitive personal identifiable information and protected health information belonging to an undetermined number of individuals.


Eisai, the U.S. based subsidiary of Tokyo, Japan-based Eisai Co., Ltd., is a pharmaceutical research and development company specializing in prescription pharmaceutical products. As a pharmaceutical manufacturing company, Eisai focuses its work on oncology and neurology, which includes dementia-related diseases and neurodegenerative diseases. In fact, in January 2023, Eisai’s treatment for Alzheimer’s disease received Accelerated Approval from the FDA. Headquartered in Nutley, New Jersey, Eisai has two U.S. based discovery labs in Cambridge, Massachusetts, and Exton, Pennsylvania. Serving markets across the world, Eisai employs more than 1,000.


Recently, Eisai discovered that it had experienced a data breach in which the sensitive personal identifiable information and protected health information in its systems may have been accessed and acquired. Through its investigation, Eisai determined that an unauthorized actor may have accessed and acquired this sensitive information between May 22, 2023, and June 3, 2023. On October 2, 2023, Eisai began contacting individuals whose information may have been impacted. The type of information exposed includes:

  • Name
  • Social Security number
  • Financial account number
  • Medical information

If you received a breach notification letter from Eisai, Inc.:

We would like to speak with you about your rights and potential legal remedies in response to this data breach. Please fill out the form, below, or contact us at (608) 237-1775 or sam@turkestrauss.com.

If you were impacted by the Eisai data breach, you may consider taking the following steps to protect your personal information.

  1. Carefully review the breach notice and retain a copy;
  2. Enroll in free credit monitoring service provided by Eisai, Inc.;
  3. Change passwords and security questions for online accounts;
  4. Regularly review account statements for signs of fraud or unauthorized activity;
  5. Monitor credit reports for signs of identity theft; and
  6. Contact a credit bureau(s) to request a temporary fraud alert.

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