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Feds purchase 300,000 courses of potential monkeypox drug invented at UC San Diego

Posted at 7:24 PM, Sep 02, 2022

SAN DIEGO (KGTV) – More than 300,000 treatment courses of a drug invented at UC San Diego are heading to the Strategic National Stockpile, and could provide a second antiviral treatment option for monkeypox.

The U.S. Department of Health and Human Services will pay $115 million for the initial shipment of TEMBEXA, produced by Chimerix, Inc., the company announced this week.

TEMBEXA is the brand name for brincidofovir, a drug invented by Dr. Karl Hostetler at UC San Diego in 1999. He did it by modifying the chemical structure of another drug at the request of the federal government, which urgently wanted a pill to treat smallpox.

Hostetler and his colleagues came up with the eventual formula of TEMBEXA on their first try.

“It worked right away. [The National Institutes of Health] said, ‘Can you do it?’ ‘Well, we're pretty sure we can,’” Dr. Hostetler said in an interview Friday.

Smallpox and monkeypox come from the same viral family. Lab tests show the drug works well against both viruses, according to a paper from scientists at the Food and Drug Administration.

The HHS’ 10-year contract with Chimerix, Inc. includes options that would allow the government to purchase more than one million additional doses. The government said the agreement will fortify the nation’s defense against smallpox, a virus that was eradicated by 1980 but could be used in a bioterror attack.

But the FDA has previously signaled its interest in using TEMBEXA to fight monkeypox, and Chimerix said it is in talks to launch clinical trials.

Hostetler founded Chimerix but has since left the company.

“That was exciting,” Hostetler said of learning of the purchase agreement. “Now that there is a possibility to use it in human disease, I'd like to see it used.”

TEMBEXA is FDA approved to treat smallpox, but it has not been used to treat patients with the disease because smallpox was eradicated by 1980.

Since the first cases of monkeypox began emerging in the U.S. earlier this year, patients with severe disease have only had access to one experimental antiviral called TPOXX, which was also invented for smallpox.

But TPOXX has drawbacks. Patients have to take six pills a day for 14 days – 84 pills in all. During that two-week stretch, they also have to maintain a high-fat diet.

A course of TEMBEXA is just four pills total – two pills taken on two days.

Laboratory tests on TPOXX show it has another concern: the drug can induce mutations in a pox virus that can make it resistant to treatment.

“Obviously, the biggest concern is that the [monkeypox] virus mutates, such that it's easier to transmit or becomes more lethal. We know that there are more lethal strains out there,” said Dr. Randall Lanier, chief scientific officer of Chimerix, referring to strains found in Africa.

TEMBEXA targets a different enzyme in the virus. In a paper, the FDA noted it “does not rapidly select for resistance” like TPOXX.

“Given the potential for creating a drug-resistant strain in the laboratory, [TEMBEXA] is really a critical piece of the armamentarium for the U.S.,” Lanier said.