Here come the anti-Covid antibodies

After vaccines and antiviral approaches to tackling the Covid-19 pandemic, it’s time for antibodies to take their turn in the spotlight. This week Lilly seized the lead in this space, starting the first clinical trial of an antibody designed to treat the novel coronavirus.
LY-CoV555, derived from a deal with Abcellera, targets Covid-19’s Spike protein, meaning that unlike projects aiming to reduce the infection’s complications it takes direct aim at the virus itself. While at present this is the only clinical-stage antibody against Covid-19, it will not retain this monopoly for long.
The Spike protein-targeting approach is similar to that of several of Lilly’s competitors. The protein is present on the virus surface, and the virus uses it to dock with the Ace2 receptor on target cells, allowing it to be internalised and infect.
The next project into the clinic with this mechanism could come from Vir’s partnership with Glaxosmithkline, which has so far identified two lead MAbs. Also keenly awaited are a multi-antibody cocktail from Regeneron, and a project under way at Astrazeneca, all of which could be studied in patients within the next few months.
The hope is that these antibodies can prevent the virus docking, or hit another part of it that leads to antibody-mediated destruction.
The last two are noteworthy because they are based in part on plasma derived from patients who have recovered from Covid-19 infection. This approach, it might be surmised, could provide a broader range of targets, some of which might provide a more efficient way of targeting the virus than hitting the Spike protein.

Selected antibodies and related biologicals in development for Covid-19
Companies	Lead, if identified	Mechanistic approach	Clinical development?
Lilly/Abcellera	LY-CoV555	IgG1 MAb vs Spike protein	Safety study in hospitalised subjects
Sab Biotherapeutics	SAB-185	Polyclonal	Clinical trial due mid-2020
Regeneron	REGN-COV2	Multi-Ab cocktail, incl from recovered patients	Clinical trial due Jun 2020
Celltrion	CT-P59	MAb vs Spike protein receptor binding domain	Clinical trial due Jul 2020
Glaxosmithkline/Vir	VIR-7831 & VIR-7832	MAbs vs Spike protein	Clinical trial in Jul-Sep 2020
Astrazeneca	–	MAbs, incl based on recovered patients	Clinical trial in Jul-Sep 2020
Sorrento	STI-1499	Fully human MAb vs Spike protein	Clinical trial due Q3 2020
Brill Bio	–	Fully human MAb	Clinical trial due Q3 2020
Yumab	–	MAbs, incl based on recovered patients	Clinical trial due H2 2020
Molecular Partners	–	Darpin proteins	Clinical trial due H2 2020
Systimmune	SI-F019	Bivalent Ace2 fusion protein vs Spike protein	IND filing due 2020
Xencor/Vir	–	Fc-engineered MAbs	–
Lilly/Junshi	JS016	Fully human MAb vs Spike protein	–
Atreca/Beigene/IGM	–	IgM & IgA MAbs vs novel epitopes	–
Amgen/Adaptive	–	MAbs based on recovered patients	–
Ossianix	–	Single-domain VNAR MAbs vs Spike protein	–
Sorrento	STI-4398	Ace2-Fc protein vs Spike protein	–
Sorrento/Mabpharm	STI-4920	Bispecific vs 2 domains on Spike protein	–
Note: excludes anti-IL6, anti-GM-CSF and other MAbs not directly targeting Covid-19.

The Spike protein is also used as the target for most of the industry’s vaccine approaches seeking to prime the immune system, and indeed Regeneron has suggested that REGN-COV2 could also have a prophylactic role.
And there are other biologicals already in clinical development, such as MAbs against cytokines, GM-CSF and angiopoietin 2, but these are not considered here as they aim to treat the effects of Covid-19, such as cytokine elevations and respiratory complications, rather that the virus itself.
Design
Though many projects have the same target in common, there is additional variability in antibody structure.
For instance, while most are based on IgG, a tie-up between Atreca, Beigene and IGM Biosciences is looking at those derived from IgM and IgA, which, the companies argue, have more binding domains and hence greater binding power than IgG.
A separate tie-up Vir has with Xencor looks to develop MAbs with an engineered Fc domain to give an extended half-life, and a similar thinking lies behind the so-called Darpins in development by Molecular Partners.
There are also bispecific approaches and fusion proteins, for instance SI-F019, in development by Systimmune, a private US group focusing on MAbs, bispecifics and antibody-dug conjugates. This combines two proteins each mimicking Ace2, aiming to take up the relevant binding sites on Covid-19 and prevent its interaction with the endogenous Ace2 receptor.
While many companies are making claims about the superiority of their respective approaches, these are of course all based on animal or in vitro data, and no comparison will be possible until the first clinical trials read out.
After Lilly’s clinical study, primarily testing safety, pharmacokinetics and pharmacodynamics, the designs of competitor trials will be watched with interest.
https://www.evaluate.com/vantage/articles/news/trial-results/here-come-anti-covid-antibodies