Covid-19 treatment therapies: Monoclonal antibodies and how they work

Roche’s REGEN-CoV2 antibody cocktail treatment is gathering steam in India after it was found to be life-saving for some of the most severely affected Covid-19 patients during clinical trials performed in the UK. Can this new treatment be instrumental in helping Covid-19 patients in India? Here is a closer analysis.

What are monoclonal antibodies?

The body’s immune system combats foreign intrusion like a viral infection by creating proteins known as antibodies. Monoclonal antibodies are artificial antibodies that are produced by extracting antibodies from human blood and then cloning them. These antibodies target a specific part of the virus, like in the case of Covid-19, its SARS-CoV-2 spike protein. The monoclonal antibodies bind to the specific part of spike protein and block them from infecting healthy cells.

Treatment through injecting monoclonal antibodies has been earlier done for treatment of HIV, Cancer, and Ebola.

How can they help in Covid-19 treatment?

Dr. Anthony Fauci, Chief Medical Advisor to the US President, also director of the US National Institute of Allergy and Infectious Diseases has suggested that the monoclonal antibody treatment has proved to retain activity even against multiple variants of Covid-19. Research has shown it reduces the risk of hospitalization to a great extent.

The treatment comes with its limitations. It has so far been approved only for patients with mild to moderate symptoms, not under critical care or require oxygen. Hence it is important to provide to the right patient at right time considering the resource-constrained settings for best results, says Dr D Behera, former HOD at PGIMER Chandigarh’s Department of Pulmonology, also a Padma Shri recipient.

Dr V K Paul, NITI Aayog’s Member-Health and the Chair of the National Expert Group on Vaccine Administration against Covid-19 suggests that that the monoclonal antibodies are ineffective on the emerging Delta Plus variant.

What new study on the therapy suggests

The University of Oxford’s trials suggest that Regeneron’s monoclonal antibody reduced the risk of deaths by a fifth for patients with severe Covid-19 who had not developed a natural antibody response compared to those who received standard care. The therapy also reduced the hospital stay of some patients by four days and chances of ventilator requirement. However, when studied on the overall population including the ones who can grow natural immune response, it did not show much benefit.

So the trials suggest it can yield results for those who cannot develop a natural immune response even if they have severe symptoms and have been hospitalised. With the first large trial covering close to 10, 000 participants and conducted through eight months, a definitive conclusion can be derived that the treatment reduced deaths significantly even with severe Covid-19.

Availability of therapy for India

The REGEN-COV2 therapy, a combination of monoclonal antibodies imdevimab, and casirivimab got the nod of the Central Drugs Standard Control Organisation for restricted use in May. It is now available through a tie-up between Indian drug major Cipla and Swiss firm Roche. It was first administered to an 84-year-old in Haryana at Medanta Hospital.

Another antibody cocktail therapy — Eli Lilly’s bamlanivimab and etesevimab also got emergency use approval. Also, GlaxoSmithKline’s Sotrivimab that got US FDA’s Emergency Use Approval is eyeing to enter Indian markets. However, they are also approved only on high-risk patients with mild to moderate Covid-19.

Ahmedabad-based Zyndus Cadila also plans to conduct trials of its anti-body cocktail, ZRC-3308.

Cost of treatment

These therapies marketed by foreign companies are expensive considering they are difficult to formulate and time-consuming. EGEN-COV2 retails at Rs 1.20 lakh per pack with one pack treating two patients. Eli Lilly is in talks with the Indian government to “donate” its antibody cocktail.

The therapy is formulated in tissue culture. The cells produce the protein that gets purified, said microbiologists involved in the process. It is different from convalescent plasma therapy.

How antibody cocktail is different from plasma therapy

The Indian government recently dropped convalescent plasma therapy as an option from the guidance of covid-19 treatment after evidence from trials in last eight months has shown
No significant improvement in patients.

But scientists find antibody cocktail therapy promising. Unlike plasma therapy where antibodies are extracted from Covid recovered person and injected on a patient, the monoclonal antibodies are mass-manufactured under a controlled environment and provide a combination of two or more such antibodies.

Fauci told MedPage Today that while plasma has a lot of other things that can lead to allergic reactions but monoclonal antibodies are “extremely pure: due to its homogenous nature and data from trials reveal they are a “promising form of treatment. ”