Sanofi said Kevzara – which it produces with partner Regeneron – had failed as a COVID-19 treatment after the latest set of trials in patients across the world showed adverse effects, and would be dropped for studies in this field.

Sanofi said the trials had led in some cases to COVID-19 pneumonia infections and even death in a few cases, Reuters reported.

The two companies do not anticipate conducting further clinical studies of it, Sanofi added.

Trials had shown that the drug did not help patients with less severe COVID-19, the companies had said in July.

“Although this trial did not yield the results we hoped for, we are proud of the work that was achieved by the team to further our understanding of the potential use of Kevzara for the treatment of COVID-19,” said Sanofi’s global head of research and development, John Reed.

“At Sanofi, we are committed to help combat the global COVID-19 pandemic, including developing vaccine candidates that can be manufactured at large scale,” he added.

Pharmaceutical companies have been racing to develop treatments against the COVID-19 pandemic that has claimed more than 849,000 lives and crippled economies.

Last month, CEO Paul Hudson said Sanofi’s confidence in its coronavirus vaccine candidates had increased over the summer as the drugmaker prepared to start clinical trials.

In July, Roche said its attempt to retool its rheumatoid arthritis drug Actemra/RoActemra to treat patients hospitalized with severe COVID-19-related pneumonia has failed in a late-stage trial.

The British drug maker, whose COVID-19 vaccine candidate is already among the most advanced, said the early-stage trial would evaluate if AZD7442, a combination of two monoclonal antibodies (mAbs), was safe and tolerable in up to 48 healthy participants between the ages of 18 and 55 years.

If the UK-based trial has a positive readout, AstraZeneca said it would proceed with larger, mid-to-late-stage trials to test AZD7442 as both a preventative treatment for the disease and a medicine for patients who have it, Reuters reported.

Monoclonal antibodies mimic natural antibodies generated in the body to fight off infection and can be synthesized in the laboratory to treat diseases in patients and has been endorsed by top scientists.

Current uses include treatment of some types of cancers.

London-listed AstraZeneca in June received US$23.7 million (S$32.5 million) in funding from US government agencies to advance development of antibody-based treatments for the novel coronavirus.

US based companies Regeneron and Eli Lilly are also testing mAbs-based treatments for COVID-19.