The FDA is cracking down on stem cell clinics that administer unproven and potentially dangerous treatments to patients, citing a California-based clinic that the regulatory watchdog said was treating cancer patients with the smallpox vaccine.

Last week, the U.S. Marshals Service seized five vials of a vaccine that is reserved only for people at high risk for smallpox. The FDA said that StemImmune, a stem cell clinic in San Diego, had mixed the vaccine with fat-derived stem cells and injected it intravenously into patients’ tumors at the California Stem Cell Treatment Centers.

The FDA said it “has serious concerns” as to how StemImmune obtained the product, since it is not sold commercially, and that it is actively investigating.

“Speaking as a cancer survivor, I know all too well the fear and anxiety the diagnosis of cancer can have on a patient and their loved ones and how tempting it can be to believe the audacious but ultimately hollow claims made by these kinds of unscrupulous clinics or others selling so-called cures,” FDA Commissioner Dr. Scott Gottlieb said in prepared remarks.

“The FDA will not allow deceitful actors to take advantage of vulnerable patients by purporting to have treatments or cures for serious diseases without any proof that they actually work. I especially won’t allow cases such as this one to go unchallenged, where we have good medical reasons to believe these purported treatments can actually harm patients and make their conditions worse.”

The agency pointed out that serious, sometimes life-threatening problems can occur in unvaccinated people who are accidentally infected with the virus by being in contact with someone who has recently been given the vaccine.

“I’ve directed the agency to vigorously investigate these kinds of unscrupulous clinics using the full range of our tools, be it regulatory enforcement or criminal investigations. Our actions today should also be a warning to others who may be doing similar harm, we will take action to ensure Americans are not put at unnecessary risk,” Gottlieb added. “I also urge health care providers, patients and consumers to report these kinds of activities or any adverse events associated with these unproven treatments to the agency through MedWatch.”

In another statement, the FDA issued a warning letter to Florida-based U.S. Stem Cell, pointing towards a recent inspection of the clinic which found that it was using fat-derived stem cells to treat conditions including Parkinson’s disease and ALS.

In March, an article in the New England Journal of Medicine revealed that three women with age-related macular degeneration were blinded or visually impaired after stem cells were injected into their eyeballs at the clinic.

Gottlieb also published a policy statement about cell therapies today, calling them “one of the most promising new fields of science.”

“However, with all of the medical potential, also comes novelty and uncertainty as this field matures. There are a small number of unscrupulous actors who have seized on the clinical promise of regenerative medicine, while exploiting the uncertainty, in order to make deceptive, and sometimes corrupt, assurances to patients based on unproven and, in some cases, dangerously dubious products,” he wrote.

“These dishonest actors exploit the sincere reports of the significant clinical potential of properly developed products as a way of deceiving patients and preying on the optimism of patients facing bad illnesses. This puts the entire field at risk.”

The FDA commissioner said he is putting together a new working group at the agency to go after “unscrupulous clinics” and that the FDA will develop a framework to accelerate approval for responsible developers of stem cell therapies.

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