Antibody cocktail seen as potential game changer as India battles virus

Traumatised by its recent calamitous battle with Covid-19 and apprehensive of a third wave, India has found a silver lining in a new treatment for Covid-19 patients - a powerful infusion of laboratory-made antibodies.

Several Indian hospitals reported encouraging results after using it on some patients. They showed quick recovery, even avoiding hospitalisation in some cases and medication such as steroids, which have been linked to post-Covid complications like mucormycosis, a deadly fungal infection.

At AIG Hospitals in Hyderabad, 50 patients with mild to moderate Covid-19 were in the last three weeks given a dose of Regen-Cov, a cocktail of two monoclonal antibodies designed by American biotech firm Regeneron. Symptoms in all the patients subsided within 24 to 48 hours of their being administered the therapy.

Some 38 even tested negative in reverse transcription polymerase chain reaction (RT-PCR) tests conducted a week after they had received their doses. The other 12 have to be either tested or are awaiting their results. None of them were admitted to hospital and the therapy was administered to them intravenously as outpatients. Dr D. Nageshwar Reddy, the chairman of AIG Hospitals, said the patients received no medication except paracetamol to manage fever. "Most of them after 24 hours did not require paracetamol also," he told The Straits Times.

A monoclonal antibody is a laboratory-made protein that mimics the body's immune response.

India granted emergency use authorisation to Regen-Cov on May 4, around the peak of its second wave. Casirivimab and imdevimab, the monoclonal antibodies that make up the cocktail, bind specifically to two different sites on the coronavirus spike protein, blocking viral attachment and entry into human cells. The drug is meant for patients who are at high risk of developing severe Covid-19 and do not require respiratory support.

At AIG Hospitals, the patients who received the therapy were aged over 65 and had risk factors such as obesity, uncontrolled diabetes, immunosuppression and kidney disease.

Another 35 such vulnerable patients with mild to moderate Covid-19 also received a single intravenous dose of the cocktail at Manipal Hospital on Old Airport Road in Bangalore. None had to be admitted to the intensive care unit or needed respiratory support.

"All 35 patients were happily discharged," said Dr Satyanarayana Mysore, the head of department of pulmonology at Manipal Hospitals. The patients' average duration of hospital stay was around 36 hours and they are doing well, he told ST.

Results released yesterday from the Recovery trial in the United Kingdom, described as the world's largest trial of Covid-19 therapeutics, demonstrated that Regen-Cov reduced the risk of death even when given to patients hospitalised with severe Covid-19 who have not mounted a natural antibody response of their own.

For every 100 such patients treated with the antibody combination, researchers calculated, there would be six fewer deaths. The treatment was given in addition to the anti-inflammatory steroid drug dexamethasone. Patients who have made their own antibodies to the virus, however, do not benefit from the antibody cocktail.

Monoclonal antibody treatment for Covid-19 has been described as a "game changer" by some in India because it could help cut down on hospitalisation costs, besides freeing up healthcare facilities for non-Covid patients. However, a single dose of the cocktail comprising 600 mg of each antibody costs around 60,000 rupees (S$1,085), a sum beyond the reach of many Indian families.

The drug is not sold at pharmacies and is available only through hospitals, an arrangement doctors have suggested be continued to avoid any indiscriminate use. "The medical force will and should not cave under pressure to give monoclonal antibody treatment just because somebody demands it. It should be merit-based and criteria-based, and based on proper education," Dr Mysore told ST.

India granted emergency use authorisation for another antibody cocktail from United States drug manufacturer Eli Lilly on May 31.

Monoclonal antibodies are immune system proteins created in the lab.

They are engineered to serve as substitute antibodies that, according to the US Food and Drug Administration, can restore, enhance or mimic the immune system's attack on pathogens. Like human antibodies, monoclonal antibodies recognise a specific target on pathogens.

Monoclonal antibodies have been used to treat cancer, Ebola and autoimmune diseases such as rheumatoid arthritis.

Then US President Donald Trump received a cocktail of monoclonal antibodies casirivimab and imdevimab when he contracted Covid-19 in October last year.