A candidate treatment that utilizes cow antibodies to combat COVID-19 may be able to produce four times the level of neutralizing antibodies as seen in conventional human convalescent plasma serum, the compound's developer has announced.
The utilization of externally-produced antibodies to fight off a disease, termed artificial passive immunity, is a cornerstone of immunology. There has been a huge pile-on by industry to develop drugs that effectively deliver these antibodies to COVID-19 patients. Some use antibodies developed in cell lines and others use antibodies directly taken from patients who have recovered from COVID or related viruses.
A different type of herd immunity
But few utilize the approach taken by Sioux Falls, SD-headquartered SAb Biotherapeutics, who source their antibodies from genetically-modified cattle. These cattle produce human-derived antibody, bypassing the need to have human plasma donors. SAb have already used their bovine platform to trial antibodies against other viruses, like Middle East respiratory syndrome (MERS).
SAb have now claimed that their COVID-19 therapeutic antibody candidate, SAB-185, will enter into the next phase of clinical development, with plans for concomitant manufacturing to support a quick rollout. SAB-185 was based on the original Wuhan strain of SARS-CoV-2.
William B. Klimstra, PhD, associate professor of immunology and member of the Center for Vaccine Research at The University of Pittsburgh, who has been investigating the bovine antibodies, said, “These data indicate this human polyclonal antibody therapeutic has potent neutralizing activity against live SARS-CoV-2. The neutralizing titers of SAB-185 are significantly higher than those of the most potent plasma of recovered COVID-19 patients we’ve been able to source.”
Polyclonal and monoclonal antibodies
The other distinguishing feature of SAB-185 is that it is composed of a polyclonal antibody mix, rather than the more common monoclonal antibody-based approach. This means that a mix of slightly different antibodies – but all recognizing SARS-CoV-2 – are present in SAB-185, which should in theory allow for a stronger affinity against the SARS-CoV-2 virus. Polyclonal approaches are not without their drawbacks, however, as variability between batches is more of a risk than for monoclonal approaches.
Eddie J. Sullivan, PhD, president, CEO and co-founder of SAB Biotherapeutics, said, “In just seven weeks, we’ve accelerated development of a specifically targeted natural human polyclonal therapeutic, without the need for human serum, and generated large volumes of highly-potent neutralizing antibodies to SARS-CoV-2, to produce clinical lots of our COVID-19 therapeutic candidate, SAB-185.”
In their announcement, SAb raises hopes that its approach will mean a scalable, reliable source of high-potency antibodies to fight COVID-19. If SAD-185 does reach its potential, it will be, as pointed out last month by Science, the first approved treatment derived from cow-made antibodies.