Monoclonal Antibody Successful in Clearing Viral Load for Mild COVID-19 Patients

LY-CoV555, a monoclonal antibody, could become a useful treatment for emergency use in patients with recently diagnosed novel coronavirus (COVID-19) with mild to moderate cases, according to a paper published in the New England Journal of Medicine.

Investigators from across the U.S. randomly assigned 452 mild or moderate COVID-19 patients to receive one of 3 single intravenous infusions of neutralizing antibody LY-CoV555 in order to evaluate the quantitative virologic end points and clinical outcomes. This paper provides an interim analysis of the results through Sept. 5, 2020, the study authors explained, as the patients were dosed between June 17 and August 21, 2020.

The patients, who were recruited from 41 centers around the country, were administered doses of 700 mg, 2800 mg, or 7000 mg or a placebo over the course of about an hour. The investigators measured the patients’ change from baseline to day 11 in terms of their viral loads. They also noted that the doses used in their trial were based on pharmacologic modeling that predicted the 700 mg dose would be efficacious. They increased the trial dose by a factor of 10 to “ensure adequate target coverage,” they explained of the 7000 mg dose.

Nearly three-quarters of the patients were found to have at least 1 risk factor for severe illness, the study authors said, including age of 65 years or older, a body mass index of 35 or more, or at least one relevant coexisting illness.

The study authors learned that by day 11, the majority of patients trended toward total viral clearance – even those in the placebo group, they found. There were 107 patients who received the 2800 mg dose, and of those, there was a decrease from baseline compared to placebo patients of -0.53, which translated to a lower viral load by a factor of 3.4, the study authors said. There were smaller differences compared to placebo found among the 101 patients who received the 700 mg dose and the 101 patients who received the 7000 mg dose.

On day 3, the study authors found that the 2800 mg dose cohort had a decrease from baseline in mean log viral load of -0.64 compared to the placebo cohort. While the other LY-CoV555 dose cohorts also saw improvements in viral clearance by day 3 compared to the placebo group, the difference was greatest in the 2800 mg group.

By day 29, there were 1.6% of patients from the LY-CoV555 groups that were hospitalized compared to 6.3% of patients in the placebo group, the study authors noted. Percentages of hospitalized patients were similar across all 3 LY-CoV555 dose cohorts.

The study authors explained that LY-CoV555 is also called LY3819253 and was derived from convalescent plasma from a patient with COVID-19 and developed by Eli Lilly. Previous reporting demonstrated that LY-CoV555 offered passive protection against COVID-19 in nonhuman primates, the study authors noted.

The investigators reported that only 1 patient in the trial was admitted to intensive care, and that patient was from the placebo group. Additionally, no serious adverse events occurred in the total 309 patients in the LY-CoV555 cohort and just 1 of the 143 patients in the placebo group. Adverse events occurred in 22.3% of the LY-CoV555 group and 24.5% of the placebo group, they said, including diarrhea, vomiting, and nausea.