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Table 4c. COVID-19 Convalescent Plasma: Selected Clinical Trial Data

Last Updated: February 29, 2024

The studies described in this table are those that had the greatest impact on the Panel’s recommendations. The Panel reviewed other clinical studies of CCP for the treatment of COVID-19.1-5 However, those studies have limitations that make them less definitive and informative than the studies summarized in the table.

Table 4c. COVID-19 Convalescent Plasma: Selected Clinical Trial Data
Methods Results Limitations and Interpretation
REMAP-CAP: Multinational, Open-Label RCT of High-Titer CCP in Hospitalized Patients With Critical COVID-19 in Australia, Canada, the United Kingdom, and the United States6

Key Inclusion Criterion

  • Admitted to ICU while receiving respiratory support (HFNC oxygen, NIV, MV, ECMO) and/or vasopressor or inotrope support

Key Exclusion Criteria

  • CCP contraindicated
  • Death imminent

Interventions

  • High-titer CCP (550 mL +/- 150 mL) within 48 hours of randomization (n = 1,084)
  • Usual care (n = 916)

Primary Endpoint

  • Number of organ support-free days by Day 21

Key Secondary Endpoints

  • In-hospital mortality
  • Mortality by Day 28 and Day 90
  • Number of respiratory support-free days
  • ICU LOS

Participant Characteristics

  • Mean age 61 years; 68% men
  • 32% on MV
  • 29% were SARS-CoV-2 antibody negative at baseline.
  • 94% received corticosteroids; 45% received RDV; 39% received IL-6 inhibitors.

Primary Outcome

  • Median number of organ support-free days by Day 21: 0 days in CCP arm vs. 3 days in usual care arm (OR 0.97; 95% CrI, 0.82–1.14)

Secondary Outcomes

  • No difference between arms in:
    • In-hospital mortality: 37% in CCP arm vs. 38% in usual care arm
    • Mortality by Day 28 or Day 90
    • Median number of respiratory support-free days: 0 days in CCP arm vs. 2 days in usual care arm
    • Median ICU LOS: 21 days in CCP arm vs. 17 days in usual care arm
Key Limitations
  • Open-label study
  • Not all patients in CCP arm received CCP (86% received CCP as per protocol and 95% received some CCP).

Interpretation

  • There was no benefit of CCP in hospitalized patients with critical COVID-19.
CONCOR-1: Multinational, Open-Label RCT of CCP for Hospitalized Patients With COVID-19 in Canada, the United States, and Brazil7

Key Inclusion Criteria

  • Receipt of supplemental oxygen
  • Availability of ABO–compatible CCP

Key Exclusion Criteria

  • Imminent or current intubation
  • >12 days from respiratory symptom onset

Interventions

  • 1–2 units of CCP (approximately 500 mL) from 1–2 donors (n = 625)
  • SOC (n = 313) 

Primary Endpoint

  • Composite of intubation or death by Day 30

Key Secondary Endpoints

  • Time to intubation or death by Day 30
  • Mortality by Day 30 
  • ICU LOS by Day 30 
  • Need for renal dialysis by Day 30
  • Frequency of SAEs by Day 30

Participant Characteristics

  • Mean age 68 years; 59% men
  • 84% were receiving systemic corticosteroids at enrollment.

Primary Outcome

  • Composite of intubation or death by Day 30: 32% in CCP arm vs. 28% in SOC arm (relative risk 1.16; 95% CI, 0.94–1.43; P = 0.18)

Secondary Outcomes

  • By Day 30, no difference between arms in:
    • Time to intubation or death 
    • Mortality: 23% in CCP arm vs. 21% in SOC arm
    • Mean ICU LOS: 4.3 days in CCP arm vs. 3.7 days in SOC arm
    • Need for renal dialysis: 1.6% in CCP arm vs. 2.0% in SOC arm
  • Frequency of SAEs by Day 30: 33% in CCP arm vs. 26% in SOC arm
Key Limitations
  • Open-label study
  • Trial stopped at 78% of planned enrollment after meeting prespecified futility criteria for early termination.

Interpretation

  • There was no benefit of CCP in oxygen-dependent, hospitalized patients with COVID-19 who were within 12 days of symptom onset.
RECOVERY: Open-Label RCT of High-Titer CCP in Hospitalized Patients in the United Kingdom8

Key Inclusion Criterion

  • Clinically suspected or laboratory-confirmed SARS-CoV-2 infection

Key Exclusion Criterion

  • CCP contraindicated

Interventions

  • 2 units of high-titer CCP (approximately 275 mL/unit) with IgG against SARS-CoV-2 spike protein and sample to cutoff ratio ≥6.0. First unit administered ASAP after randomization; second unit administered ≥12 hours later (n = 5,795).
  • Usual care (n = 5,763)

Primary Endpoint

  • All-cause mortality by Day 28

Key Secondary Endpoints

  • Time to hospital discharge by Day 28
  • Among patients not on MV, progression to MV or death by Day 28

Participant Characteristics

  • Mean age 64 years; 64% men
  • 5% on MV
  • 92% received corticosteroids.

Primary Outcomes

  • No difference between arms in:
    • All-cause mortality by Day 28: 24% in each arm
    • Mortality in patients without detectable SARS-CoV-2 antibodies: 32% in CCP arm vs. 34% in usual care arm

Secondary Outcomes

  • No difference between arms in:
    • Proportion discharged by Day 28: 66% in both arms
    • Proportion who progressed to MV or death by Day 28: 29% in CCP arm vs. 29% in usual care arm

Key Limitation

  • Open-label study

Interpretation

  • There was no benefit of CCP in hospitalized patients with COVID-19.
RECOVER: Open-Label RCT of High-Titer CCP in Hospitalized Patients With Severe COVID-19 in 4 Risk Groups in Germany9  

Key Inclusion Criteria

  • PCR-confirmed SARS-CoV-2 infection
  • Hospitalized with SpO2 ≤94% on room air or PaO2/FiO2 <300 mm Hg
  • ≥1 of the following criteria: 
    • Hematologic cancer and/or receipt of active cancer therapy in past 24 months for any cancer 
    • Chronic immunosuppression due to medications and/or underlying disease 
    • Aged >50 to ≤75 years with ALC <0.8 x 109 cells/L and/or D-dimer >1 μg/mL  
    • Aged >75 years without other listed criteria

Key Exclusion Criterion

  • Required MV or NIV 

Interventions

  • 2 units (238–337 mL) of high-titer CCP (≥1:80) or vaccinated donor plasma from 2 donors on Days 1 and 2 (n = 68)
  • SOC (n = 66)

Primary Endpoint

  • Time to 2-point improvement on a 7-point OS or hospital discharge

Key Secondary Endpoints

  • 28-day, 56-day, and 84-day overall survival rate

Participant Characteristics

  • 136 participants were enrolled between September 2020 and January 2022.
  • Mean age 69 years; 68% men; 97% White
  • Participants were enrolled from 4 mutually exclusive patient groups:
    • Patients with cancer (n = 56)
    • Patients with immunosuppression who did not have cancer (n = 16, including 12 solid organ transplant recipients)
    • Patients aged >50 to ≤75 years with lymphopenia and/or elevated D-dimer levels (n = 36)
    • Patients aged >75 years without other criteria (n = 26)
  • 11% were fully vaccinated. 
  • 8% received small-molecule antiviral drugs (12% in plasma arm vs. 5% in SOC arm); 37% received anti-inflammatory drugs (40% in plasma arm vs. 33% in SOC arm).
  • 60% received supplemental oxygen via nasal cannula; 21% on HFNC oxygen or NIV
  • Median 7 days between symptom onset and randomization

Primary Outcome

  • Median time to 2-point improvement on OS or hospital discharge: 13 days in plasma arm vs. 18 days in SOC arm (HR 1.29; 95% CI, 0.86–1.93; P = 0.205)
    • Median time to improvement or hospital discharge among patients with cancer: 13 days in plasma arm vs. 31 days in SOC arm (HR 2.50; 95% CI, 1.34–4.79; P = 0.003)

Key Secondary Outcomes

  • No difference between arms in overall survival; 27 patients (19.9%) died (HR for survival 0.72; 95% CI, 0.33–1.55; P = 0.403).
    • Fewer patients with cancer died in plasma arm than in SOC arm (HR 0.28; 95% CI, 0.06–0.96; P = 0.042). 

Key Limitations

  • Open-label study
  • The live-virus neutralization assay used to select plasma for this trial may not produce the same results as the assays used to qualify high-titer CCP in the current FDA EUA
  • Small sample size
  • Trial was terminated early because the neutralizing activity of stored plasma against the Omicron variant was not known. 
  • Low proportion of vaccinated participants and limited use of current SOC therapies, such as antiviral or immunomodulatory agents
  • Subgroup analyses were not adjusted for multiple comparisons.

Interpretation

  • The trial did not demonstrate a benefit of high-titer CCP or vaccinated donor plasma in the overall study population. 
  • Results from the predefined subgroup analysis of patients with cancer suggest a potential benefit of CCP or vaccinated donor plasma. However, this analysis was conducted largely before the emergence of Omicron subvariants, so the results should be interpreted with caution.
CONFIDENT: Open-Label RCT of High-Titer CCP in Hospitalized Patients With COVID-19–Associated ARDS in Belgium10
Key Inclusion Criteria
  • PCR-confirmed SARS-CoV-2 infection
  • Admitted to ICU with COVID-19–associated ARDS and WHO COVID-19 OS score of 7, 8, or 9
  • On MV for ≤5 days
  • Clinical Frailty Scale score of <6 

Key Exclusion Criteria

  • Previous transfusion-related side effects
  • Medical decision to limit therapy

Interventions

  • 2 units (400–500 mL total) of high-titer CCP (≥1:320) from donors who fully recovered from COVID-19 between 28 days and 10 months before study. CCP was administered within 24 hours of study randomization (n = 237).
  • SOC (n = 238)

Primary Endpoint

  • Mortality by Day 28

Participant Characteristics

  • Median age 64 years; 68% male
  • 10% were vaccinated.
  • 10% with mild ARDS, 58% with moderate ARDS, 32% with severe ARDS
  • Baseline evidence of ongoing SARS-CoV-2 replication (Ct value of 22 in CCP arm vs. 20 in SOC arm)
  • 98% received corticosteroids; 6% received RDV; 4% received IL-6 inhibitors.

Primary Outcome

  • Mortality by Day 28: 35% in CCP arm vs. 45% in SOC arm (P = 0.03)
    • In patients on MV ≤48 hours: 33% in CCP arm vs. 47% in SOC arm 
    • In patients on MV >48 hours: 42% in CCP arm vs. 40% in SOC arm
  • Similar outcomes were seen regardless of whether the original SARS-CoV-2 strain (Wuhan-Hu-1) or the Alpha, Delta, or Omicron variants were in circulation.
Key Limitations
  • Open-label study
  • Trial was stopped after recruiting 95% of the target enrollment due to a low ICU admission rate.
  • Approximately 18% of patients who were assigned to receive CCP received a lower neutralizing titer of 1:160.
  • The live-virus neutralization assay used to select plasma for this trial may not produce the same results as the assays used to qualify high-titer CCP in the current FDA EUA
  • Low proportion of vaccinated patients and limited use of current SOC therapies, such as antiviral agents or a second immunomodulatory agent
  • There were differences in treatment effects across sites.

Interpretation

  • CCP reduced mortality by Day 28 in patients with COVID-19 and ARDS, and the effect was most notable in patients who were randomized ≤48 hours after initiating MV.
CSSC-004: RCT of Early Treatment With High-Titer CCP in Outpatients With COVID-19 in the United States11
Key Inclusion Criterion
  • COVID-19 symptoms for <8 days 

Key Exclusion Criteria

  • Prior or planned COVID-19–related hospitalization
  • Receipt of anti-SARS-CoV-2 mAbs

Interventions

  • Approximately 250 mL of CCP with SARS-CoV-2 spike protein IgG (titer ≥1:320) (n = 592)
  • Non-SARS-CoV-2 plasma (n = 589)

Primary Endpoint

  • Composite of COVID-19–related hospitalization or all-cause death within 28 days

Participant Characteristics

  • Median age 44 years; 7% aged ≥65 years; 57% women; 79% White
  • 8% with type 2 DM; 2% with CVD; 38% with BMI ≥30 
  • 82% were unvaccinated. 
  • Median of 6 days between symptom onset and transfusion

Primary Outcomes

  • COVID-19–related hospitalization within 28 days: 2.9% in CCP arm vs. 6.3% in control arm (absolute risk reduction 3.4 percentage points; 95% CI, 1.0–5.8; P = 0.005)  
  • 53 of 54 hospitalizations occurred in unvaccinated individuals. None occurred in fully vaccinated individuals.
  • All-cause deaths within 28 days: 0 in CCP arm vs. 3 in control arm
Key Limitation
  • Patients were at relatively low risk of disease progression.

Interpretation

  • This trial demonstrated a benefit of CCP in unvaccinated outpatients with <8 days of COVID-19 symptoms.
CONV-ERT: RCT of High-Titer, Methylene Blue-Treated CCP as an Early Treatment for Outpatients With COVID-19 in Spain12 
Key Inclusion Criteria
  • Aged ≥50 years 
  • Mild or moderate COVID-19 symptoms for ≤7 days

Key Exclusion Criteria

  • Severe COVID-19 symptoms or need for hospitalization for any reason
  • Previous SARS-CoV-2 infection
  • Receipt of ≥1 doses of a COVID-19 vaccine 

Interventions

  • 250–300 mL of high-titer, methylene blue-treated CCP (n = 188)
  • 0.9% saline (n = 188) 

Primary Endpoints

  • Hospitalization within 28 days 
  • Mean change in SARS-CoV-2 VL from baseline to Day 7 

Key Secondary Endpoints

  • Death by Day 60
  • Time to complete symptom resolution

Participant Characteristics

  • Mean age 56 years; 54% men
  • 75% with ≥1 risk factors for COVID-19 progression 
  • 97% with mild COVID-19
  • Median of 4.4 days of symptoms prior to enrollment
  • Among 369 patients with available baseline serologic testing, 88% were negative for both IgG anti-SARS-CoV-2 spike and IgM anti-SARS-CoV-2 S1-RBD.

Primary Outcomes

  • Hospitalization within 28 days: 12% in CCP arm vs. 11% in placebo arm (relative risk 1.05; 95% CrI, 0.78–1.41)
  • Mean change in SARS-CoV-2 VL: -2.41 log10 copies/mL in CCP arm vs. -2.32 log10 copies/mL in placebo arm

Key Secondary Outcomes

  • Death by Day 60: 0 in CCP arm vs. 2 in placebo arm (relative risk 0.20; 95% CI 0.01–4.14)
  • No difference between arms in median time to symptom resolution: 12.0 days for both arms (HR 1.05; 95% CI, 0.85–1.30) 
Key Limitations
  • Trial was underpowered because it was terminated early due to rising vaccination rates among the eligible patient population.
  • Methylene blue, which was used for pathogen inactivation in donor plasma, could have potentially impaired Fc-region functionality of Ig and negatively impacted product efficacy and blinding. 

Interpretation

  • This trial did not demonstrate a benefit of CCP in unvaccinated outpatients with ≤7 days of COVID-19 symptoms. 
Double-Blind RCT of Early High-Titer CCP Therapy to Prevent Severe COVID-19 in Nonhospitalized Older Adults in Argentina13
Key Inclusion Criteria
  • Aged ≥75 years or aged 65–74 years with ≥1 coexisting conditions
  • Mild COVID-19 symptoms for <72 hours

Key Exclusion Criterion

  • Severe respiratory disease 

Interventions

  • 250 mL of CCP with SARS-CoV-2 spike protein IgG (titer >1:1,000) (n = 80)
  • Saline (n = 80)

Primary Endpoint

  • Severe respiratory disease, defined as respiratory rate ≥30 breaths/min and/or SpO2 <93% on room air, by Day 15

Participant Characteristics

  • Mean age 77 years; 38% men
  • Most with comorbidities

Primary Outcome

  • Severe respiratory disease by Day 15: 16% in CCP arm vs. 31% in placebo arm (relative risk 0.52; 95% CI, 0.29–0.94; P = 0.03)
Key Limitations
  • Small sample size
  • Trial was terminated early because the number of COVID-19 cases decreased.

Interpretation

  • This trial demonstrated a benefit of CCP in older adult outpatients with <72 hours of mild COVID-19 symptoms.
SIREN-C3PO: Multicenter, Single-Blind RCT of High-Titer CCP in Adults With COVID-19 in the United States14 
Key Inclusion Criteria
  • ED patient with ≤7 days of symptoms
  • PCR-confirmed SARS-CoV-2 infection
  • Aged ≥50 years or aged ≥18 years with ≥1 risk factors for disease progression

Key Exclusion Criterion

  • Need for supplemental oxygen

Interventions

  • 250 mL of high-titer CCP (median titer 1:641) (n = 257)
  • Saline (n = 254)

Primary Endpoint

  • Disease progression, defined as hospital admission, death, or seeking emergency or urgent care, within 15 days of randomization

Key Secondary Endpoints

  • Severity of illness by Day 30, as measured by an OS
  • All-cause mortality by Day 30
  • Number of hospital-free days by Day 30

Participant Characteristics

  • Median age 54 years; 46% men
  • More patients with immunosuppression in CCP arm than in placebo arm (13% vs. 7%)
  • More patients with ≥3 risk factors in CCP arm than in placebo arm (55% vs. 48%)

Primary Outcomes

  • No difference between arms in proportion with disease progression: 30% in CCP arm vs. 32% in placebo arm (risk difference 1.9%; 95% CrI, -6.0% to 9.8%)
  • 25 patients (19 in CCP arm vs. 6 in placebo arm) required hospitalization during index visit. In a post hoc analysis that excluded these patients, disease progression occurred in 24% in CCP arm vs. 30% in placebo arm (risk difference 5.8%; 95% CrI, -1.9% to 13.6%).

Secondary Outcomes

  • All-cause mortality by Day 30: 5 (1.9%) in CCP arm vs. 1 (0.4%) in placebo arm
  • No difference between arms in illness severity or mean number of hospital-free days by Day 30
Key Limitations
  • In the primary analysis, the number of patients who required hospital admission during the index visit was not balanced across arms.
  • The CCP arm included more patients with multiple risk factors, including immunosuppression.

Interpretation

  • The use of high-titer CCP within 1 week of symptom onset did not prevent disease progression in outpatients with COVID-19 who were at high risk of severe disease.
CoV-Early: Double-Blind RCT of CCP in Nonhospitalized High-Risk Adults With COVID-19 in the Netherlands15
Key Inclusion Criteria
  • Aged ≥70 years, aged ≥50 years with a comorbidity, or aged ≥18 years and severely immunocompromised
  • Positive SARS-CoV-2 RT-PCR or antigen test result
  • COVID-19 symptoms for ≤7 days

Key Exclusion Criteria

  • Life expectancy <28 days
  • History of TRALI
  • IgA deficiency

Interventions

  • 300 mL of CCP with minimum PRNT50 titer of 1:160 (n = 207)
  • Non-SARS-CoV-2 plasma collected prior to pandemic (n = 209)

Primary Endpoint

  • Improvement based on 5-point OS by Day 28

Secondary Endpoints

  • Percentage of hospital admissions
  • Number of days of symptoms

Participant Characteristics

  • Median age 60 years; 22% women 
  • Median of 5 days of symptoms 
  • Median of 1 comorbidity 
  • Median SpO2 of 97% at baseline
  • 7.9% were SARS-CoV-2 IgG antibody negative at baseline.
  • 2.9% were fully vaccinated; 5.0% received 1 dose of a COVID-19 vaccine.

Primary Outcome

  • Odds of receiving highest score on 5-point OS by Day 28: OR 0.86; 95% CrI, 0.59–1.22 in CCP arm

Secondary Outcomes

  • Percentage of hospital admissions: 4.8% in CCP arm vs. 8.6% in non-SARS-CoV-2 plasma arm (aHR 0.61; 95% CI, 0.28–1.34)
  • Number of days of symptoms: 13 in CCP arm vs. 12 in non-SARS-CoV-2 plasma arm (P = 0.99)
Key Limitations
  • Study was discontinued after 421 of 690 planned participants were enrolled, resulting in decreased power.
  • The CCP used was selected based on a PRNT50 assay and may not qualify as high-titer CCP per the current FDA EUA.

Interpretation

  • This trial did not demonstrate a benefit of CCP in nonhospitalized, high-risk patients with COVID-19.
Retrospective Evaluation of CCP Antibody Levels and the Risk of Death From COVID-19 in the United States16
Key Inclusion Criteria
  • Severe or life-threatening COVID-19
  • Patients for whom samples of transfused CCP were available for retrospective analysis of antibody titer

Interventions

  • High-titer CCP (n = 515), medium-titer CCP (n = 2,006), or low-titer CCP (n = 561), characterized retrospectively

Primary Endpoint

  • Mortality by Day 30 after CCP transfusion

Participant Characteristics

  • 31% aged ≥70 years; 61% men; 48% White, 37% Hispanic/Latinx
  • 61% in ICU; 33% on MV
  • 51% received corticosteroids; 31% received RDV.

Primary Outcomes

  • Mortality by Day 30 after transfusion: 22% in high-titer CCP arm vs. 27% in medium-titer CCP arm vs. 30% in low-titer CCP arm 
    • Lower risk of death in high-titer CCP arm than low-titer CCP arm (relative risk 0.75; 95% CI, 0.61–0.93)
  • Lower mortality among patients not receiving MV before CCP transfusion (relative risk 0.66; 95% CI, 0.48–0.91)
  • No difference in mortality between high-titer and low-titer arms among patients on MV before CCP transfusion (relative risk 1.02; 95% CI, 0.78–1.32)
Key Limitation
  • Lack of untreated control arm

Interpretation

  • The study data are not sufficient to establish the efficacy or safety of CCP.

References

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