Sorrento surges on antibody ‘shield’ trials for coronavirus

Shares in Sorrento Therapeutics rose 158% on Friday after it revealed plans to start human trials of an antibody therapy that achieved complete inhibition of the coronavirus in preclinical studies.

The small San Diego biotech developed the drug candidate after screening “convalescent” plasma from around 15,000 people who were suspected of having recovered from COVID-19, and says it should be ready to start clinical trials in the third quarter.

The screening used a diagnostic test developed by Florian Krammer of Icahn School of Medicine at Mount Sinai, that was deployed under an FDA emergency use authorisation (EUA) as the coronavirus pandemic took hold in the US.

The two partners plan to develop a series of drug cocktails based on antibodies specific to SARS-CoV-2, the virus that causes COVID-19, that they say could be used as a “protective shield” against infection for up to two months.

The approach could be used to provide passive immunity, for example for healthcare workers returning to duty, and as a therapy for people who have already been infected with the coronavirus, says Sorrento.

Using a cocktail means the therapy should also remain effective even if viral mutations develop that reduce the activity of a single antibody.

The company says it has found an antibody – codenamed STI-1499 – that can achieve “100% inhibition of SARS-CoV-2 virus infection of healthy cells after four days incubation,” and will soon submit the data to a peer-review journal for independent assessment.

All told, the screening process has so far generated around a dozen antibody candidates that could be used as therapy for COVID-19, all targeting the S1 subunit of the spike protein that the virus uses to latch onto human cells.

STI-1499 was a most potent, completely neutralising virus infectivity at a very low antibody dose, making it a prime candidate for further testing and development.

It is also being developed as a standalone therapy as COVI-GUARD, while Sorrento plans to use COVI-SHIELD as the brand name for its antibody cocktail therapy.

Screening plasma for potential antibodies against an infectious disease is a tried and tested approach in drug development, and has already been used to develop therapies for other coronaviruses such as SARS-CoV-1, which caused an outbreak in 2002-2004.

Others groups are also applying this technique to SARS-CoV-2, and scientists in China have suggested it can lessen the severity or shorten the length of illness caused by COVID-19.

Last month, a group of the world’s leading plasma companies – led by Takeda and CSL Behring – launched a consortium that aims to develop an ‘unbranded’ therapy for COVID-19.

Meanwhile, the Mayo Clinic and American Red Cross have also been given FDA approval to test convalescent plasma and antibody cocktails against the virus.

With some heavyweight players already operating in this space, Sorrento says it is “seeking potential government support and pharmaceutical partners to further scale up STI-1499 manufacturing capacity with a goal of potentially providing tens of millions of doses.”

The biotech’s current manufacturing capacity is around 200,000 doses a month, and it says it plans to produce a million doses at-risk whilst seeking FDA approval for its therapy.