Efprezimod Alfa (CD24Fc, MK-7110) as a Non-antiviral Immunomodulator in COVID-19 Treatment (MK-7110-007)

Time to improvement in COVID-19 clinical status: defined as time (days) required from start of treatment to improvement of clinical status severe - moderate/mild or improvement from score 2-4 to ≥5 sustained without drop below 5 within 28 days from randomization, total follow-up period 29 days (Randomization Day 1 + 28 days follow up) per National Institute of Allergy & Infectious Diseases (NIAID) ordinal scale graded: 1=Death; 2=Hospitalized, on invasive mechanical ventilation (IMV)/extracorporeal membrane oxygenation (ECMO); 3=Hospitalized, on non-invasive ventilation (NIV)/high flow oxygen devices; 4=Hospitalized, require supplemental oxygen; 5=Hospitalized, no supplemental oxygen, require medical care; 6=Hospitalized, no supplemental oxygen, don't require medical care; 7=Not hospitalized, limitation on activities &/or require home oxygen; 8=Not hospitalized, no limitations on activities. Median time & 95% confidence intervals (CIs) were reported using Brookmeyer-Crowley method.

An AE was defined as any unfavorable and unintended sign including an abnormal laboratory finding, symptom or disease associated with the use of a medical treatment or procedure, regardless of whether it is considered related to the medical treatment or procedure, that occurs during the course of the study. Per protocol, only AEs with Common Terminology Criteria for AE (CTACAE) grade ≥3 were included. The number of participants who experienced an AE were reported.

RF was defined as the need for any of the following: 1) mechanical ventilation (MV), 2) ECMO, 3) NIV, or 4) high flow oxygen devices. Percentage of participants who died or had respiratory failure by Day 29 were reported.

Time to disease progression in clinical status is defined as the time (days) for progression from NIAID score (3 or 4) to (2 or 1) or from 2 to 1 within 28 days from randomization, total follow-up period 29 days (Randomization Day 1 + 28 days follow up). NIAID ordinal scale graded as: 1=Death; 2=Hospitalized, on IMV/ECMO; 3=Hospitalized, on NIV/high flow oxygen devices; 4= Hospitalized, require supplemental oxygen; 5=Hospitalized, no supplemental oxygen, require medical care; 6=Hospitalized, no supplemental oxygen, do not require medical care; 7=Not Hospitalized, limitation on activities and/or require home oxygen; 8=Not hospitalized, no limitations on activities.

Number of participants who died due to any cause were assessed per protocol on Day 15 and Day 29.

Rate of clinical relapse was defined as the percentage of participants who had initially reached score 5 on NIAID ordinal scale for more than one day but subsequently became dependent on oxygen support for more than 1 day within 28 days from randomization after initial recovery with a total follow-up period of 29 days (Day 1 of randomization plus 28 days of follow-up). NIAID ordinal scale graded as: 1=Death; 2=Hospitalized, on IMV/ECMO; 3=Hospitalized, on NIV/high flow oxygen devices; 4= Hospitalized, require supplemental oxygen; 5=Hospitalized, no supplemental oxygen, require medical care; 6=Hospitalized, no supplemental oxygen, do not require medical care; 7=Not hospitalized, limitation on activities and/or require home oxygen; 8=Not hospitalized, no limitations on activities. Clopper-Pearson method was used to report the 95% CI.

Conversion rate of COVID-19 clinical status on days 8 and 15 was defined as the percentage of participants who changed from NIAID ordinal score 2, 3, 4 to score 5 or higher and reported. NIAID ordinal scale graded as: 1=Death; 2=Hospitalized, on IMV/ECMO; 3=Hospitalized, on NIV/high flow oxygen devices; 4= Hospitalized, require supplemental oxygen; 5=Hospitalized, no supplemental oxygen, require medical care; 6=Hospitalized, no supplemental oxygen, do not require medical care; 7=Not hospitalized, limitation on activities and/or require home oxygen; 8=Not hospitalized, no limitations on activities.

The hospital discharge time was defined as the time from randomization to discharge from the hospital and reported. Time to Hospital Discharge (days) from randomization is calculated as: Time to hospital discharge = Date of hospital discharge - Date of randomization.

MV included IMV and NIV. Duration of MV (days) was calculated as: End Date of MV - Start Date of MV + 1 and reported.

Pressor administration included norepinephrine, epinephrine, vasopressin, dopamine and phenylephrine. Duration of pressor (days) was defined as: End Date of Pressor - Start Date of Pressor + 1 and reported.

Duration of ECMO treatment (days) was calculated as: End Date of ECMO Treatment - Start Date of ECMO Treatment + 1 and reported.

Duration of oxygen therapy (oxygen inhalation by high flow nasal cannula or mask) (days) was calculated as: End Date of high flow oxygen therapy - Start Date of high flow oxygen therapy + 1 and reported.

Length of Hospital Stay (Days) was defined as date of discharge - date of admission + 1 and reported. Data presented below include hospitalization time prior to enrollment in the study with total duration of up to 90 days.

Blood samples were collected to present the change from baseline in the absolute lymphocyte count on days 1, 4, 8, and 15 in peripheral blood. To calculate the change from baseline in absolute lymphocyte count at specific timepoints (Days 1, 4, 8 and 15), only the participants who had both, a baseline, and a post baseline value at the specific timepoint (Days 1, 4, 8 and 15) were included in the analysis.

Blood samples were collected to present the change from baseline in the D-dimer concentration on days 4, 8 and 15 in peripheral blood. To calculate change from baseline in D-dimer concentration at specific timepoints (Days 4, 8 and 15), only the participants who had both, a baseline, and a post baseline value at the specific timepoint (Days 4, 8 and 15) were included in the analysis.