IBRX Shares Tumble 21.2% After FDA Misbranding Warning
ImmunityBio's stock (NASDAQ: IBRX) suffered a sharp decline on March 24, 2026, after a U.S. Food and Drug Administration (FDA) warning letter over its marketing practices became public. Shares of the biotechnology company dropped $1.99, or 21.2%, to close at $7.41 from a previous close of $9.40. The sell-off was a direct reaction to regulatory criticism of promotional materials for its lead cancer drug, Anktiva.
The FDA's letter, dated March 13 but publicized on March 24, identified a TV advertisement and a podcast as making "false or misleading" statements. The agency found these communications violated the Federal Food, Drug, and Cosmetic Act, raising public health concerns over the misrepresentation of Anktiva's approved uses. This was not the first time the company was warned; the FDA had sent similar letters to an ImmunityBio subsidiary on September 9, 2025, and January 7, 2026.
Lawsuits Allege Overstated Claims for Cancer Drug Anktiva
In the wake of the stock's collapse, several law firms, including Robbins Geller Rudman & Dowd LLP and Rosen Law Firm, announced the filing of class-action lawsuits. The suits charge ImmunityBio and its Executive Chairman, Dr. Patrick Soon-Shiong, with violating the Securities Exchange Act of 1934. The core allegation is that the company materially overstated the capabilities of Anktiva and failed to disclose the ongoing regulatory issues.
The FDA letter explicitly took issue with promotional content that created a "misleading impression that Anktiva, a treatment for a certain type of bladder cancer, can cure and even prevent all cancer." Lawsuits allege these statements were part of a pattern of misrepresentation to investors, which ultimately led to substantial financial losses when the true details were revealed to the market.
Investors Have Until May 26 to Seek Lead Plaintiff Status
The lawsuits cover investors who purchased ImmunityBio securities between January 19, 2026, and March 24, 2026. According to the legal notices, investors who suffered substantial losses during this period have until May 26, 2026, to file a motion with the court to be appointed as lead plaintiff. The lead plaintiff represents the interests of all class members in directing the litigation.
