A lab-made cocktail of antibodies has entered late-stage clinical trials in the US to evaluate its ability to prevent and treat coronavirus disease (Covid-19), which has infected at least 12.5 million people and killed around 560,00 of them worldwide since December.

The US biotechnology firm Regeneron announced the start of its Phase 3 experimental monoclonal antibody cocktail REGN-COV2 against Covid-19 this week in collaboration is the US National Institute of Allergy and Infectious Diseases (NIAID). The late phase trial will assess its ability to prevent infection among close contacts of infected people, such as family members.

Monoclonal antibodies are lab-made proteins that act like natural antibodies and work by identifying and binding to the virus to destroy it. They are currently being used to treat several diseases and conditions, including cancers, asthma, Crohn’s disease, and rheumatoid arthritis.

REGN-COV2’s two antibodies bind non-competitively to the critical receptor binding domain of the virus’s spike protein to prevent infection.

REGN-COV2 has also moved into the Phase 2/3 portion of two adaptive Phase 1/2/3 trials testing the cocktail’s ability to treat hospitalised and non-hospitalised (ambulatory) patients with Covid-19. These trials will involve 1,850 hospitalised patients and 1,050 ambulatory patients at 150 sites in the US, Brazil, Mexico and Chile. The preliminary data expected later this summer, according to Regeneron.

“We are running simultaneous adaptive trials in order to move as quickly as possible to provide a potential solution to prevent and treat Covid-19 infections, even in the midst of an ongoing global pandemic,” Dr George D. Yancopoulos, co-founder, president and chief scientific officer of Regeneron, said in the company’s news release.

Regeneron’s antibody cocktail will be tested in four separate study populations, which included hospitalised Covid-19 patients; people with mild disease; healthy people at a high risk for getting infected; and healthy people who have come into close contact with a person who is sick.

US-based pharma giant Eli Lilly and Canada-based AbCellera have also started testing their antibody treatment in humans June 1.

Multi-centric studies to evaluate the off-label use of the anti-inflammatory monoclonal antibody drug Tocilizumab to treat Covid-19 began in India last month. This second-line drug is used to treat rheumatoid arthritis and works by lowering aberrant host immune response that leads to inflammatory cytokine storm and death in hospitalised Covid-19 patients. Inflammatory cytokine storm stops oxygenation by impeding gas exchange in the lungs, leading to death.

“Tocilizumab is already available, licenced and effective in treating cytokine release syndrome caused by other conditions. The Covid-19 trial is going well, the recruitment is at the halfway mark within a month. We have recruited around 90 of the 180 patients for treatment across 14 hospitals in 10 cities, and hope to complete recruitment by the end of July and get initial data by August 15,” said Dr Arvinder Soin, national lead, Indian multi-centre trial on Tocilizumab in moderate and severe Covid-19.

The trial will be conducted in several hospitals in Delhi-NCR, Haryana, Maharashtra, Uttar Pradesh, Telangana and Tamil Nadu. “Off-label use for Tocilizumab is approved for moderate to severe patients whose condition is worsening, and the trial is an attempt to evaluate whether the drug will also prevent the progression of stable moderate disease to severe Covid-19 needing oxygen or ventilator,” said Dr Soin, who is also chairman, Medanta Liver Institute, Medanta, Gurugram.

“The trial will show if it works or not. I think we should give science a chance to provide evidence-based data, so that we can ensure fair access to all to the most effective treatments against Covid-19,” said Dr Soin.

Regeneron’s monoclonal antibody trials will be a part of the NIAID’s newly launched Covid-19 Prevention Trials Network (COVPN) to test vaccines and other treatments against Covid-19 through the merger of four previously existing clinical trials networks that focused on HIV/Aids. COVPN is a functional unit of Operation Warp Speed, the US federal partnership focused on speeding the development and delivery of COVID-19 diagnostics, therapeutics and vaccines.

Moderna’s mRNA-1273 vaccine, which was developed jointly with NIAID, is expected to be tested in the first phase 3 clinical trial conducted through COVPN.