Trump takes Regeneron's antibodies, Gilead's remdesivir, dexamethasone in first days of COVID-19 hospital stay

President Donald J. Trump's medical team is navigating an uncertain COVID treatment course for the nation's now-hospitalized leader. With Trump's symptoms "up and down," his physicians are throwing the kitchen sink at the virus, including a steroid therapy typically reserved for the most dire cases.

This weekend, Trump's personal doctor told reporters the president had been treated with Gilead Sciences' investigational antiviral remdesivir as well as dexamethasone, a common generic steroid that has shown clinical promise in cutting severe COVID-19 patients' death rates. 

Both treatments followed an 8-gram dose of Regeneron's investigational antibody cocktail, dubbed REGN-COV2, administered after the president's Thursday diagnosis, along with aspirin and famotidine, better known as branded Pepcid. The president was also taking zinc and vitamin D, two typical immune-boosting supplements, according to a Friday memo from his physician, Dr. Sean Conley.

Trump spent the weekend in treatment at Walter Reed Medical Center in Bethesda, Maryland, after being airlifted there by helicopter late Friday afternoon. The president reportedly experienced two drops in oxygen saturation levels below 94% before being hospitalized, Conley told reporters Sunday.

Despite what Conley called "frequent ups and downs" in his condition, Trump said he was "feeling much better" in a Saturday video posted on Twitter, and then made an eyebrow-raising drive-by to wave to supporters outside Walter Reed on Sunday.  

The broad treatment course the president is receiving has little clinical data backing up its efficacy but may indicate Trump's condition, SVB Leerink Geoffrey Porges said in a note to clients. 

For one, Regeneron's cocktail showed limited use in patients with a low viral load, indicating Trump may have been diagnosed as seronegative for antibodies with a high viral load at time of treatment. Adding remdesivir and dexamethasone on top of that—a treatment course with "zero information," Porges wrote—could indicate Trump's condition was "worst than first suggested" and could be at high risk of deteriorating in the coming days.

"As every sentient human being now recognizes, being 74 yrs old and overweight are significant independent risk factors for serious complications of COVID," Porges wrote. "Having a poor immune response (which must have been observed) is another important one."

Regeneron's antibodies are among the few potential therapies for COVID-19 that have shown promise in clinical trials. Regeneron recently posted early results from an adaptive phase 1/2/3 study showing the therapy lowered virus levels and relieved symptoms more quickly than standard of care in patients infected with COVID-19 but not sick enough to be hospitalized.

RELATED: Regeneron's COVID-19 antibody cocktail curbs virus, speeds recovery in early data

REGN-COV2 has no emergency use approvals anywhere in the world—a fact that could underscore Trump's relationship with New York-based Regeneron and CEO Len Schleifer, who has been a guest at the White House during the pandemic.

The company said late Friday that Trump's doctors had requested the therapy under its compassionate use program.