Nov 18 (Reuters) - AstraZeneca, Eli Lilly, Regeneron and GlaxoSmithKline are among the biggest pharmaceutical companies to have developed COVID-19 treatments using a class of drugs called monoclonal antibodies. Laboratory-made monoclonal antibodies mimic natural antibodies in fighting off infections. Unlike vaccines, they do not rely on the body to create an immune response, and can therefore help individuals with weak or compromised immune systems. Below is an outline of where the major drugmakers are in the development and regulatory process: ASTRAZENECA (AZN.L) * AstraZeneca"s antibody cocktail AZD7442 is delivered by intramuscular shot. * On Oct. 5 the company requested emergency use approval (EUA) from U.S. regulators for the therapy, as a preventative drug. * On Oct. 11 it said it would also submit the new treatment data to global health regulators. * On Oct. 14, the EU drug regulator said it had started a real-time review of the therapy. TRIALS: * On Nov. 18, AstraZeneca said the cocktail offered 83% protection against a symptomatic form of the illness over six months. * A separate study in patients with mild-to-moderate COVID-19 showed a higher dose of AZD7442 cut the risk of symptoms worsening by 88% when given within three days of first symptoms. * Earlier in October, data showed AZD7442 reduced the risk of severe COVID-19 or death by 50% in non-hospitalised patients who have had symptoms for seven days or less. * In June, the drugmaker said a late-stage trial had failed to provide evidence that the therapy could stop individuals who had been exposed to the virus from contracting it. SUPPLY DEALS: * AstraZeneca said in March it would supply up to 500,000 more doses of the therapy to the U.S., extending a prior agreement made in October for 200,000 doses. The deal is contingent on an EUA from the FDA. read more * The British government also has an in-principle agreement for over a million doses. ELI LILLY & CO (LLY.N) * The U.S. pharmaceutical group"s treatment, a combination of the antibodies bamlanivimab and etesevimab, is meant for patients with mild-to-moderate COVID-19. * It so far given by infusion, or drip, only. * In February it was granted an EUA by the FDA for treatment of patients at high risk of severe illness who have not been hospitalised or require oxygen therapy. * The U.S. Department of Health and Human Services paused distribution in June after the drug failed to show effectiveness against several COVID-19 variants, but resumed it for some states at the end of August. read more * In September, the FDA revised its EUA to include use in at-risk patients who have been exposed to the virus. * In a letter dated Oct. 29, Eli Lilly withdrew its request for EU authorisation, saying lack of demand in the trading bloc did not justify submitting further required data on its manufacturing plan. TRIALS: * The combination helped cut the risk of hospitalisation and death in patients by 70%, early data from a late-stage trial showed in January. read more * January data from a trial of one of the therapy"s components, bamlanivimab, also showed it could cut the risk of infection by 80% for nursing home residents. read more SUPPLY DEALS: * The U.S. bought 100,000 doses of the dual antibody cocktails in February, followed by 388,000 doses of etesevimab in September. The country had already committed to buying a total of 1,450,000 doses of bamlanivimab alone. GLAXOSMITHKLINE (GSK.L) * GlaxoSmithKline (GSK.L) and Vir Biotechnology (VIR.O) partnered to develop the COVID-19 antibody drug sotrovimab. * It was shown in a trial to work as well when given as a shot in the arm as when administered as an infusion. * In May, the FDA granted sotrovimab an EUA for treating mild-to-moderate COVID-19 in people aged 12 years and older. * The EU"s drug regulator backed in June its use for patients at risk of severe disease who do not need supplemental oxygen. read more * It received approval as a COVID-19 treatment in Japan in September. TRIALS: * The treatment resulted in a 79% reduction in risk of hospitalisation for more than 24 hours or death due to any cause, a late-stage study showed in June. read more SUPPLY DEALS: * The United States has signed contracts worth about $1 billion to secure the treatment, with supply expected by Dec. 17. * The EU signed in July a contract with GSK for the supply of up to 220,000 doses of sotrovimab. * It also signed a deal to supply 10,000 doses to Canada. read more REGENERON (REGN.O) * The single-dose antibody cocktail Ronapreve, known as REGEN-COV in the United States and developed by Regeneron and Roche is a combination of two antibodies (casirivimab and imdevimab), and can be taken via injection or infusion. * Mid-July, Japan became the first country to authorise the treatment, swiftly followed by the United States and Britain. read more * REGEN-COV has now received emergency approval from more than 20 countries for both the prevention and treatment of the virus. * On Nov. 11, the EU drug regulator recommended Ronapreve for treatment in patients over 12 who do not require oxygen support and are at high risk of severe disease, and for prevention in people over 12 weighing at least 40 kilograms (88 lb). TRIALS: * Regeneron said on Nov. 8 that a single dose reduced the risk of contracting COVID-19 by 81.6% in a late-stage trial, in the two to eight months following the drug"s administration. * In June, a late-stage trial showed the cocktail reduced the risk of death by 20% for hospitalised patients whose own immune systems had failed to produce a response. * Earlier in April, it was revealed that REGEN-COV helped cut the risk of symptomatic infections by 81% among people in households where another member had become ill. SUPPLY DEALS: * As of September, the U.S. government has purchased nearly 3 million doses. * In June, the EU secured 55,000 doses through a contract covering 37 European countries, including Britain and other non-EU nations. read more Compiled by Lucinda Langlands-Perry and Valentine Baldassari in Gdansk; Editing by Milla Nissi, David Evans and Philippa Fletcher Our Standards: The Thomson Reuters Trust Principles.