Trials for EIi Lilly's coronavirus antibody treatment paused over a 'potential safety concern' less than a week after the firm applied for emergency FDA approval of its experimental drug

• Eli Lilly did not reveal the nature of the safety concerns when trials were paused
• It has also failed to detail how many of the participants in the trial were affected
• Trials of their two experimental antibody treatments for coronavirus are on hold 

Trials for Eli Lilly coronavirus antibody drugs have been put on hold due to 'potential safety concerns', less than a week after they were put forward for emergency approval for patients.

Eli Lilly did not reveal what the safety concerns were, or how many hospitalized participants were affected, after a pause was recommended by an independent safety board. 

The firm's trials of the antibody therapy - similar to the Regeneron treatment given to President Trump - are funded by the US government. 

Both LY-CoV555 and LY-CoV016 had been put forward for emergency approval by the Food and Drug Administration (FDA) in the US. It is not clear which had its trials suspended.

Early trials have shown they reduced symptoms, the amount of virus, hospitalizations and ER visits for 112 patients with mild or moderate Covid-19.

They work by having antibodies for coronavirus injected into the bloodstream, which it is hoped will help to fight off the infection faster. 

It is common for drug trials to be paused during treatment development, so that suspected side-effects can be assessed. 

Johnson & Johnson also paused its vaccine trial on Monday due to 'unexplained illness' in one participant. And the US arm of the trial for Oxford University and AstraZeneca's vaccine has been on hold since last month, though testing has resumed at all other sites.

An Eli Lilly spokesperson said: 'Safety is of the utmost importance to Lilly. 

'We are aware that, out of an abundance of caution, the ACTIV-3 independent data safety monitoring board (DSMB) has recommended a pause in enrollment. The trial, evaluating Lilly’s investigational neutralizing antibody as a treatment for COVID-19 in hospitalized patients, is sponsored by the National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health (NIH).

'Lilly is supportive of the decision by the independent DSMB to cautiously ensure the safety of the patients participating in this study.'

The company recently published data on trials for a combination of two candidate antibody drugs it had developed and of 'monotherapy' with just one of those antibody treatments. 

In studies of the single therapy - LY-CoV555, for which which the firm has asked the FDA for emergency approval - there were 'isolated drug-related reactions or hypersensitivity that were generally mild (two reported as serious infusion reactions, all patients recovered),' the company said in an October 7 statement. 

Lilly did not elaborate on the specifics of these reactions. Infusion reactions are usually characterized by chills, fever, mild low blood pressure, rash or slightly labored breathing. They're akin to an allergic reaction. 

More severe reactions can include heart issues or anaphylaxis. These can be dangerous, but are rare.   

The most pressing safety concern with these treatments is a phenomenon known as antibody-dependent enhancement (ABE). 

In ABE, antibodies inadvertently supercharge a viral infection, making it worse instead of better. ABE is hard to predict without thorough testing. 

The better match a neutralizing antibody is for the virus, however, the lesser the odds the pathogen will turn the antibodies against a patient. 

So far, Lilly has not made any mention of side effects that match the description of ABE.   

The pharma giant, Lilly, asked the US government to allow emergency use of its experimental antibody therapy  for coronavirus on Wednesday, less than a week ago. 

Its application is based on early results from a study that suggested the drug reduced symptoms, the amount of virus, hospitalizations and ER visits for patients with mild or moderate COVID-19.

Eli Lilly and Company announced the partial results Wednesday in a news release; they have not yet been published or reviewed by independent scientists.

Its drug is similar to one that President Donald Trump received on Friday, which is made by Lilly competitor, Regeneron. 

These medicines supply concentrated versions of specific antibodies to help the immune system clear the coronavirus that causes COVID-19. 

They're given as a one-time treatment through an IV.

Lilly has already started making one of the two antibodies in its drug, betting that ongoing studies would prove it worthwhile.

It´s not clear if the evidence will be viewed as strong enough for the Food and Drug Administration to grant emergency use authorization, as it has done for the antiviral drug remdesivir.

The results are an interim look at a mid-stage study in which 112 people received the antibodies and 156 got a placebo.

The amount of virus was significantly lower 11 days later in those given the drug - the main goal of the study. Virus levels were also lower at earlier time points in the course of the study. Symptom scores were better at three days.

About 5.8 percent of patients given placebo required hospitalization or an emergency room visit versus 0.9 percent of those given the antibodies.

Some scientists believe an antibody treatment designed to 'neutralize' coronavirus is the best hope for a medicine and, while some lab-made antibodies have shown promise in lab studies, Lilly's was the first to be tested in humans.  

The experimental treatment, LY-CoV555, has been developed through collaboration with privately held AbCellera Biologics, which Lilly partnered with in March.

Lilly's treatment is an antibody directed against the spike-shaped protein structures of the virus and is designed to block it from locking on to human cells, thus neutralizing the virus.

The drugmaker said the antibody treatment was developed after it was identified from a blood sample taken from one of the first US patients who recovered from the lung illness caused by the new coronavirus.

Lilly said it expects to move into the next phase of testing, studying the potential treatment in non-hospitalized COVID-19 patients, if the drug is shown to be safe.

Rival Regeneron began clinical studies in June to test its antibody cocktail treatment for the new coronavirus and is aiming to have hundreds of thousands of preventative doses available by the end of August.

Its antibody 'cocktail' drug was used to treat President Trump after he tested positive for COVID-19 last week, but the cocktail is still very much experimental and in clinical trials. 

Eli Lilly was initially experimenting with just one antibody, but its latest trial data comes from its tests of a combination treatment for COVID-19, two lab-made antibodies, LY-CoV555 and LY-CoV016. 

Ultimately, the firm requested an EUA for just one of the two antibody drugs, LY-CoV555. 

After seven days of treatment with the pair of antibodies, 20.8 percent of patients had lower viral loads than when they'd initiated treatment, compared to just three percent of those who got placebo treatment. 

Only 0.9 percent of coronavirus patients who got the treatment had to be hospitalized or needed to visit the ER, compared to 5.8 percent in the placebo group. 

'We believe the data generated to date provide sufficient evidence that both monotherapy and combination therapy may be effective to treat COVID-19 in patients with a high risk for serious outcomes,' said Dr Daniel Skovronsky, Lilly's chief scientific officer.