Investing.com -- ImmunityBio shares fell as much as 30% when markets opened in New York on Tuesday, before recovering some losses to trade roughly 18% lower shortly before 11am, after the company disclosed a Food and Drug Administration warning letter for false and misleading promotion of its bladder cancer drug Anktiva.

The FDA letter, dated March 13, cited violations in promotional materials including a television advertisement and podcast featuring company executives that made misleading claims about the drug's effectiveness and approved uses. The promotional materials suggested Anktiva could cure and prevent all types of cancer, when the drug is only approved for treating a specific type of bladder cancer in combination with BCG therapy.

The FDA's Office of Prescription Drug Promotion identified violations in promotional materials featuring CEO Richard Adcock and Executive Chairman Dr. Patrick Soon-Shiong. These included claims that Anktiva could treat all cancers, prevent cancer in radiation-exposed individuals, and function as a single injection treatment. The agency noted these representations were not supported by clinical data.

The warning letter also addressed the company's failure to properly present risk information and omission of material facts about the drug's approved indication. The FDA noted that the podcast was not submitted at the time of initial publication as required by regulations.

ImmunityBio has 15 working days to respond to the warning letter with a plan to address the violations and implement corrective communications to audiences who received the misleading promotional materials.