New research suggests that the casirivimab-imdevimab monoclonal antibody treatment for COVID-19 could have been delivered via injection instead of intravenously. There was no statistically significant difference in 28-day hospitalization or death in those treated intravenously and via subcutaneous injection.
The findings, published in JAMA Network Open, aren’t directly relevant at the moment, since the casirivimab-imdevimab treatment was abandoned when it failed to work during the Omicron outbreak. However, they point toward the importance of studying multiple routes of administration, said study lead author and pharmacist Erin K. McCreary, PharmD, of the University of Pittsburgh, in an interview.
“It would be beneficial for all future monoclonal antibodies for COVID-19 to be studied subcutaneously or intramuscularly, if possible, since that’s logistically easier than IV in the outpatient setting,” she said.
According to Dr. McCreary, an outpatient casirivimab-imdevimab treatment was used from 2020 to 2022 to treat higher-risk patients with mild to moderate COVID-19. The treatment was typically given intravenously as recommended by the federal government’s Emergency Use Authorization, she said. Clinical trials of the treatment, according to the study, allowed only IV administration.
“However, during the Delta surge, we were faced with so many patient referrals for treatment and staffing shortages that we couldn’t accommodate every patient unless we switched to [the] subcutaneous route,” Dr. McCreary said. This approach shortened appointment times by 30 minutes vs. infusion, she said.
There are many benefits to subcutaneous administration versus IV, Dr. McCreary said. “You don’t need to start an intravenous line, so you avoid the line kit and the nursing time needed for that. You draw up the drug directly into syringes and inject under the skin, so you avoid the need for a fluid bag to mix the drug in and run intravenously,” she said. “The appointment times are shorter, so you can accommodate more patients per day. Pharmacy interns can give subcutaneous injections, so you avoid the need for a nurse trained in placing intravenous lines.”
The researchers prospectively assigned 1,959 matched adults with mild to moderate COVID-19 to subcutaneous or intravenous treatment. Of 969 patients who received the subcutaneous treatment (mean age, 53.8; 56.4% women), the 28-day rate of hospitalization or death was 3.4%. Of 1,216 patients who received intravenous treatment (mean age, 54.3; 54.4% women), the rate was 1.7%. The difference was not statistically significant (P = .16).
Among 1,306 nontreated controls, 7.0% were hospitalized or died within 28 days (risk ratio = 0.48 vs. subcutaneous treatment group; 95% confidence interval, 0.30-0.80; P = .002).
“We did not find any patients where IV is a must,” Dr. McCreary said. “However, our study wasn’t powered to see a difference in certain subgroups.”
In an interview, University of Toronto internal medicine and pharmacology/toxicology physician Peter Wu, MD, said he agrees that the study has value because it emphasizes the importance of testing whether monoclonal antibodies can be administered in ways other than intravenously.
However, in the larger picture, he said, this may be irrelevant since it’s clear that anti-spike treatments are not holding up against COVID-19 variants.
No study funding is reported. Some study authors reported disclosures outside the submitted work. Dr. Wu has disclosed no relevant financial relationships.
A version of this article first appeared on Medscape.com.