Coronavirus variants escape effects of antibody drugs

The following is a roundup of some of the latest scientific studies on the novel coronavirus and efforts to find treatments and vaccines for Covid-19, the illness caused by the virus.

Coronavirus variants escape effects of antibody drugs

Antibody therapies and vaccines for treating or preventing Covid-19 are likely to be less effective against some of the new variants of the coronavirus circulating around the world, a new study suggests.

Of particular concern is the variant identified in South Africa and another one first found in Brazil with similar features. In lab tests, Eli Lilly and Co's antibody bamlanivimab was inactive against the South Africa strain, according to a report posted on Tuesday on bioRxiv ahead of peer review.

The drug just last week had shown an ability to cut the risk of Covid-19 by 80% for nursing home residents. The activity of one antibody in Regeneron Pharmaceuticals's dual-antibody therapy was impaired by the South Africa variant, although the cocktail remained potent.

South African virus variant may resist antibody drugs

And tests of blood from people who got either of the Covid-19 vaccines from Pfizer or Moderna showed antibodies generated by the shots were less effective against the South Africa variant, although Moderna has said it still believes its vaccine will provide protection.

"Mutationally, this virus is traveling in a direction that could ultimately lead to escape from our current therapeutic and prophylactic interventions," the researchers said.

"If the rampant spread of the virus continues and more critical mutations accumulate, then we may be condemned to chasing after the evolving SARS-CoV-2 continually, as we have long done for influenza virus." Lilly and Regeneron said this week that they are working on new versions of their drugs to address the new variants.

Antibody cocktail may protect patients’ household contacts

A two-drug antibody cocktail from Regeneron Pharmaceuticals called REGEN-COV prevents Covid-19 in people exposed to an infected household member, preliminary data suggest.

In an ongoing study, REGEN-COV, containing the drugs casirivimab and imdevimab, has so far caused a 100% reduction in symptomatic infection and roughly 50% lower overall rates of infection, the company announced on Tuesday.

The results suggest that the cocktail may not only reduce transmission of the virus but may also reduce disease severity in those who get infected, said Regeneron research chief and co-founder George Yancopoulos.

The therapy, which would be given to those in close contact with an infected person, immediately delivers virus-fighting antibodies into the body as opposed to vaccines that spur the body's immune system to develop its own antibodies over weeks.

German scientists make paralysed mice walk again

"This approach could protect patients receiving chemotherapy for cancer, enable control/prevention of outbreaks in an institutional setting and reduce pressure on health services," said Dr Penny Ward from King's College London. The initial data comes from the first 409 subjects of a trial that hopes to recruit 2,450 participants. Full data from the trial are expected in April.

Blood cancer drug shows promise against Covid-19

A drug used in Australia to treat blood cancer might be a powerful treatment for Covid-19, new research suggests. The drug, plitidepsin - also known as aplidin - acts against a protein in cells the virus uses to replicate.

In test-tube experiments with human lung cells, plitidepsin was 27.5-fold more potent than Gilead Sciences' remdesivir at inhibiting the virus, researchers reported on Monday in Science. In mice with Covid-19, the drug produced a 99% reduction of viral loads in the lungs and reduced inflammation. Researchers have begun testing the drug in humans with Covid-19 and are working with regulatory agencies on plans for larger trials.

Rather than targeting a protein in the virus, as many drugs do, plitidepsin targets a protein in patients' cells. This means that if the drug proves successful in humans, the virus could not easily gain resistance through mutation.