Medical Technology

Antibody Therapy is Effective for Immunodeficient COVID-19 Patients

NEW YORK (Reuters Health) – Patients with immunodeficiency-associated antibody disorders and a longstanding SARS-CoV-2 infection improved substantially after receiving compassionate-use casirivimab and imdevimab, an investigational antibody therapy sold under the brand name REGEN-COV and authorized in the U.S. for emergency use as post-exposure prophylaxis, a new study shows.

The retrospective analysis of data from 37 patients who had COVID-19 for 21 or more days prior to treatment with REGEN-COV revealed that the treatment was associated with rapid viral clearance and clinical improvement, researchers report in Clinical Infectious Diseases.

“Because people with immunocompromising conditions cannot generate their own antibodies against SARS-COV-2, in many ways they remain prisoners of the pandemic who are at higher risk of poor outcomes and are often not fully protected by vaccination,” said study coauthor Dr. David Weinreich, executive vice president of global clinical development at Regeneron Pharmaceuticals, Inc., which sells the medication. “It’s important that they have effective options both for prevention and treatment of COVID-19.”

“In our large-scale treatment studies patients typically received REGEN-COV in a shorter timeframe following diagnosis, versus these compassionate use patients who often had long-standing COVID-19,” Dr. Weinreich told Reuters Health by email. “However, this data was entirely consistent with our Phase 2 and 3 studies of REGEN-COV, which together show that the investigational antibody cocktail can result in clinical improvement in many different patient populations. The data from this case series describe high recovery rates comparable to people in the Phase 2 and 3 studies who had not yet mounted an immune response.”

To take a closer look at the impact of REGEN-COV in immunocompromised patients with long-standing COVID-19, Dr. Weinreich and his colleagues conducted a retrospective descriptive analysis using de-identified data from patients who received the medication under emergency compassionate use from September 2, 2020, to March 29, 2021. Patients were eligible to receive the medication under compassionate use if they had a serious life-threatening disease, had evidence of a positive risk-benefit ratio for using the experimental medication, were not eligible for a clinical trial and had no viable/available treatment options.

Out of a total of 174 U.S. patients approved to receive REGEN-COV under the program, 95 had primary and/or secondary immunodeficiency-associated antibody disorders. Of the patients who received the medication and for whom there was available data, 37 had COVID-19 duration of 21 or more days prior to treatment. Among these patients, the mean age was 49 years and 65% were male.

Three patients (8.1%) had primary immunodeficiency-associated antibody disorders and 34 had secondary causes of these antibody disorders, most commonly caused by treatment with anti-CD20 (rituximab), acute lymphocytic leukemia, follicular lymphoma, diffuse B-cell lymphoma, and other non-Hodgkin’s lymphomas.

Of the 37 patients with longstanding COVID-19 prior to treatment, qualitative or quantitative outcome were available for 29. Overall, 96.6% of the patients, or 28 out of 29, showed improvement in one or more measures after treatment.

In the 14 patients with post-treatment RT-PCR results available, 78.6% reported a negative test after treatment, with five (45.5%) reporting a negative RT-PCR within five days and eight within 21 days of treatment.

Serious adverse reactions were experienced in 10 of the larger group of 85 patients (11.8%), of which just one was an infusion-related reaction judged as possibly related to the medication.

“Unfortunately, COVID-19 remains a major burden after almost two years, and even more so for people who are immunocompromised,” Dr. Weinreich said. “We encourage all people to understand their options for both preventing and treating COVID-19, and in particular to seek out treatment early if you are at particularly high risk for serious consequences.”

SOURCE: Clinical Infectious Diseases, online December 31, 2021.

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