FDA officials said that a security rule finalized in late 2024 under the previous administration, and implemented in April, limits exports of sensitive data to China and other countries of concern, but that the rule contains an exemption for companies sending biological samples such as DNA for processing overseas as part of trials regulated by the agency.

Dr. Marty Makary, the FDA's commissioner, and Dr. Vinay Prasad, head of the FDA's Center for Biologics Evaluation and Research, said in a video released by the agency that they only learned about the exception this week.

"Americans have their, can have their cells removed for cancer treatment, sent to China, where they are genetically engineered that is genetically edited, sent back to the United States, where it's then infused back into an American," Makary said. "And so from a pure national security standpoint, it sounds very concerning."

Prasad said that the cells "can be engineered to be potent killers of targets that can be found anywhere" and that scientists may not be able to fully test them on their way back into the United States.

"In cases of personal health information, Americans' identity, in cases of national security, I think we have to be extremely strict and really protect American interests here," he added later.

The FDA said in a statement that there are signs that Americans participating in some of the trials were not informed about their biological material being sent overseas, and that the transfer may have exposed the genetic data to misuse by foreign governments, including the Chinese Communist Party.

The agency said it is now reviewing all of the trials that relied on the exemption to the security rule. Officials say they're going to require that companies "demonstrate full transparency, ethical consent, and domestic handling of sensitive biological materials" before trials are allowed to resume.

National Institutes of Health (NIH) Director Dr. Jay Bhattacharya welcomed the development.