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Experts question lack of clinical data to support FDA decision on monoclonal antibody treatments

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Eva Marie Uzcategui/Bloomberg via Getty Images

The U.S. Food and Drug Administration used the results of laboratory experiments in its sudden and unexpected decision to revoke the emergency use authorizations for certain monoclonal antibody treatments for COVID-19, stating that data showed the treatments were ineffective against the Omicron variant.

On Monday, the FDA announced that the Eli Lilly and the REGEN-COV treatments would no longer be made available to health care providers in areas where Omicron is the dominant COVID-19 variant, including states like Florida, where the treatments have been accessible for months. The decision was slammed by Florida Gov. Ron DeSantis (R), who has encouraged the use of monoclonal antibodies as an effective early treatment for those infected with coronavirus. In a statement responding to the announcement, DeSantis criticized the Biden administration for taking away the treatment option "without a shred of clinical data to support this action."

In Monday's announcement, FDA press officer Chanapa Tantibanchachai wrote that "the most recent information and data available today" supported its determination to de-authorize the monoclonal antibody treatments.

“Because data show these treatments are highly unlikely to be active against the omicron variant, which is circulating at a very high frequency throughout the United States, these treatments are not authorized for use in any U.S. states, territories, and jurisdictions at this time,” the FDA stated. “In the future, if patients in certain geographic regions are likely to be infected or exposed to a variant that is susceptible to these treatments, then use of these treatments may be authorized in these regions.”

TheBlaze reached out to Tantibanchachai requesting a copy of the data cited in the press release. The FDA provided two fact sheets given to health care providers that reported the results of in vitro lab experiments with bamlanivimab-etesevimab and REGEN-COV.

Experts confirmed the reports appear to show that in a lab setting, the monoclonal antibody treatments appear to less effective against the Omicron variant.

"Regarding the sheets you sent, it appears to report the results of an in vitro lab experiment, which found that when Casirivimab and Imdevimab are used together versus a 'pseudotyped virus-like particle' (I assume the spike protein), they are substantially less likely to neutralize the simulated Omicron particles than they were versus simulated versions of particles from the previous variants," said Dr. Jay Bhattacharya, a professor of medicine at Stanford University. Casirivimab and imdevimab are the names of the drugs used in Regeneron's REGEN-COV treatment.

"These results suggest that mABs are less likely to work when given to patients with an Omicron infection than they did versus earlier variants, but the sheets do not provide any clinical evidence from real world use of these medications on patients to verify the findings," he added.

The lack of clinical data for mAb treatments against Omicron — the results of real-world studies with COVID-19 patients — is a criticism the DeSantis administration has leveled against the FDA's decision. The governor and his spokesmen have also observed that mAb treatments have saved lives and questioned why the Biden administration would remove that treatment option.

Kyle Lamb, a researcher with the communications office for DeSantis, told TheBlaze that before the Omicron variant appeared, the mAb treatment manufactured by Regeneron "demonstrated a 70-80 percent reduction in hospitalization and death from COVID-19."

"In Florida, we saw over a 90 percent reduction in total hospitalizations within a few months of implementing monoclonal antibody treatment, due in part both to the peak of our seasonal summer wave and also the success of over 4,000 new mAbs patients a day in our statewide treatment locations," Lamb said.

After reviewing the data from the FDA, Lamb observed that the agency admits on page 45 of its fact-sheet for REGEN-COV "it is not known" how the results of these lab experiments "correlate with clinical outcomes."

"All the evidence given thus far relates to these mAbs being significantly less effective in providing neutralizing antibodies against omicron, but their own literature acknowledges they don't know how well the treatment will hold up against clinical illness," Lamb said.

"Here in Florida, we are still receiving feedback from practitioners and hospitals statewide that they are observing what they believe to be some level of effectiveness against clinical disease, even with Omicron cases," he added.

"That is why we are adamant that the FDA and HHS should be using clinical data to support this decision, and should be transparent with the data they are basing these actions."

DeSantis' critics point out that U.S. Centers for Disease Control and Prevention models indicate the Omicron variant is responsible for 99% of COVID infections in the state, which if true means the Eli Lilly and REGEN-COV treatments may not actually help coronavirus patients.

But Lamb reiterated that the DeSantis administration disagrees with the FDA decision because its data is "not based on real world results against clinical disease."

"More importantly, the decision was also partially based on models by the CDC as to the degree in which Delta has been crowded out by Omicron. If these models even slightly overstate the prevalence of Omicron, hundreds of thousands of Americans could be susceptible to manifestation of more severe disease seen in Delta without access to the most proven treatment option we have," Lamb said.

Bhattacharya agreed with that assessment.

"I do not understand why the FDA pulled mABs since they are still useful versus the Delta strain. Though it is no longer common, there are still patients who are infected with it and mABs have been shown to substantially reduce hospitalization and mortality risk if given early. Pulling the EUA denies those patients an effective early treatment," he said.

Lamb also accused the FDA of being inconsistent regarding the authorizations of COVID-19 treatments that have been shown to have varying effectiveness against Omicron.

"The decision to authorize emergency use for Merck's antiviral pill was in spite of clinical data that demonstrated disappointing results. Another treatment option, Remdesivir, has been conditionally recommended against use by the World Health Organization since November 2020 due to a lack of efficacy against disease in COVID-19 yet it remains authorized by the FDA due to a complete lack of evidence that it is effective," he said.

"Even vaccines are far less efficacious in preventing transmission against Omicron, including boosters. We are puzzled by the inconsistent logic pushed forward by this administration when it comes to treatment options for Floridians and Americans nationwide."

The CDC maintains that evidence supports the effectiveness of FDA authorized or approved vaccines and booster shots against infection, hospitalization, and death from COVID-19.

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