What is an antibody cocktail, is it effective against COVID-19, Zee explains

NEW DELHI: While vaccination continues to play a major role in combating the COVID-19 virus, doctors across the world have been using various other innovative medical techniques, therapies to treat coronavirus patients.

Antibody therapy or antibody-drug cocktail is one such thing. The therapy first drew attention after it was used to treat former United States President Donald Trump last year. Recent clinical studies have shown that antibody therapy or antibody-drug cocktail can reduce the chance of hospitalisation by 70 per cent in patients with mild to moderate COVID-19 symptoms.

What is an antibody therapy or antibody cocktail?

The antibody therapy is a cocktail of two monoclonal antibodies - Casirivimab-Imdevimab injection - and was designed specifically to block the infectivity of SARS-CoV-2, the virus that causes Covid-19. The monoclonal antibodies are produced by recombinant DNA technology. Monoclonal antibodies are artificially created in a laboratory and tailor-made to fight a particular disease.

What are antibodies?

To understand the working of antibodies, think of them as soldiers. As soldiers protect the nation and strengthen its defences against the enemies, antibodies protect our bodies and strengthen our defence mechanism against a particular disease like coronavirus. Antibodies are simply proteins that the body generates to defend itself against any disease. 

How does it work?

As part of this single-dose infusion-based treatment, patients with mild to moderate symptoms are offered a cocktail of Casirivimab and Imdevimab. Cipla and Switzerland-based Roche have launched this antibody cocktail in the market for the treatment of COVID patients.

Explaining how the therapy works, Dr Ashok Seth, chairman, Fortis Escorts Heart Institute (FEHI), South Delhi and cardiologist, says similar to antibodies, which are proteins that the body naturally generates to defend itself against disease, monoclonal antibodies are "artificially created in the lab".

Casirivimab and Imdevimab used in this cocktail are monoclonal antibodies that are specifically directed against the spike protein of SARS-CoV-2, aimed to block the coronavirus' attachment and entry into human cells, Dr Seth says.

Two distinct antibodies bind non-competitively to the COVID-19 virus-cell surface and prevent the virus from infecting healthy cells. Using two antibodies protects against the emergence of resistance, according to Medanta Hospital.

Is antibody therapy being used in India?

Recently, Mohabbat Singh, an 84-year-old COVID-19 positive man, was given monoclonal antibody therapy at Medanta Hospital in Gurgaon. He was sent home the same day and kept under observation. The hospital authorities later said that Singh became the first patient to receive the therapy at Medanta. The hospital claimed that it was Delhi-NCR's first case of monoclonal antibody therapy for a COVID-19 patient.

"The antibody combination of Casirivimab and Imdevimab, now available in India, is a cutting-edge treatment that will provide protection to COVID-19 positive patients with mild or moderate symptoms before they deteriorate further or require hospitalisation," the Medanta Hospital said in a statement.

Who should be given an antibody cocktail?

The therapy is most suited for "high-risk COVID-19 patients" who are within the first ten days of symptom onset and meet any of the listed criteria, such as age being 65 years or above, according to the Medanta Hospital. Other criteria include obesity with BMI (Body Mass Index) of more than 35; or type 1 or type 2 diabetes mellitus; or chronic kidney disease, including those on dialysis; or chronic liver disease; or currently receiving immunosuppressive treatment; or if aged above 55, have either heart disease or hypertension or chronic lung disease.

This therapy is meant for people who are under home isolation and do not need oxygen support, so the cut-off level of SpO2 is about 93 per cent, and are at high risk due to their co-morbidities such as liver disease, heart ailments or chronic lung disease, according to Dr Seth.

It is not meant for people in ICU or on ventilators or needing any kind of oxygen support. Also, those patients who have anaphylaxis which could entail severe allergic reaction.

How is an antibody cocktail administered?

An antibody cocktail is administered intravenously or subcutaneously (under the skin) as an injection. The intravenous administration takes about 20 to 30 minutes. For the subcutaneous route, four syringes of 2.5 ml (2 each of Casirivimab & Imdevimab) need to be administered concurrently at four different sites on the abdomen or thigh.

Patients should be monitored during the infusion and observed for least one hour after the completion of the infusion and 15--30 minutes after the subcutaneous injection.

Has the antibody therapy got the necessary approvals? 

The therapy has been approved by the Food & Drug Administration of the United States. It has also been cleared by India’s top drug regulator the Drugs Controller General of India (DCGI). Earlier this month, the Central Drugs Standards Control Organisation (CDSCO) had provided an Emergency Use Authorisation (EUA) for the antibody cocktail (Casirivimab and Imdevimab) in India. It has also received a EUA in the US and several EU countries.

What are the results of clinical trials?

This FDA-approved therapy has demonstrated good efficacy in Phase 1/2 and Phase 3 studies by reducing COVID-19 related hospitalisation and deaths by 70 per cent. The results of its Phase-III global trials in high-risk non-hospitalised Covid-19 patients were announced by Roche in March this year. 

After the DCGI nod, this single dose infusion-based treatment can now be provided on an outpatient or daycare basis and marks a dramatic shift in COVID-19 care in India.

Is it available in India?

Roche India has announced the rollout of its first batch of antibody cocktail (Casirivimab and Imdevimab) against Coronavirus in India. The cocktail drug will be marketed by Cipla pan-India. The second batch of the cocktail jabs will be made available by mid-June. Together, they can potentially benefit 200,000 patients as each of the 100,000 packs that will be available in India offers treatment for two patients, the company said in a statement. 

The cocktail drug can be procured only by a medical prescription and may only be administered in settings in which health care providers have immediate access to medications to treat infusion reactions, such as anaphylaxis.

Zydus Cadila seeks DCGI approval 

Zydus Cadila, which is the only Indian company to have developed a neutralizing monoclonal antibody-based cocktail for the treatment of COVID-19, has sought DCGI approval for a clinical trial. The company said that its biological therapy ZRC-3308, a cocktail of two SARS-CoV-2-neutralizing monoclonal antibodies (mAbs) can emerge as one of the main treatments for mild COVID-19.

What is the cost of the antibody cocktail?

The price for each patient dose (a combined dose of 1200 mg (600 mg of Casirivimab and 600 mg of Imdevimab) will be Rs 59,750. The maximum retail price for the multi-dose pack (each pack can treat two patients) is Rs 119,500, according to Roche India.