Fudan University published a preprint: neutralizing antibodies that are effective against new crown mutant strains

The scientific research team composed of Wang Qiao's laboratory and Ai Di Weixin Biopharmaceutical of Fudan University School of Basic Medicine discovered a broad-spectrum neutralizing antibody XG005, which is highly effective against all domestic new crown mutant strains, and verified through experiments that it has super high neutralizing activity against various strains such as new coronavirus wild type, Alpha, Beta, Gamma, Delta, OmicronBA.
1, BA.
2, BA.
3, BA.
4/5, etc.
, and has been engineered through engineering transformation.
A corresponding monoclonal antibody drug ADV2301 (XG005M)
was developed.
The latest results show that it still maintains a high degree of neutralizing efficacy
against BA.
5.
2 and BF.
7 mutant strains that are circulating in China.

Recently, the related paper "Fortuitous Somatic Mutations during Antibody Evolution Endow Broad Neutralization against SARS-CoV-2 Omicron Variants" has been published
in the bioRxiv preprint.

The paper shows that the researchers have made engineering modifications
based on XG005.
The modified antibody molecule, on the basis of the ultra-high and high school activity of the original neutralizing antibody, can significantly avoid the potential ADE (antibody dependence enhancement) side effects and enhance the safety of the drug.
And the half-life of the antibody has been extended, and the effective concentration maintenance time may reach more than
half a year.
This means that in addition to the therapeutic effect, this antibody drug may also have a long-term infection prevention effect and provide passive immune protection
.

XG005 neutralizing antibody was isolated by researchers from the serum of people who recovered from wild-type strain infection, and a total of 48 antibodies were isolated from serum, and one of them, XG005, was found to be against all mutant strains WT, B.
1.
1.
7 (Alpha), B.
1.
351 (Beta), P.
1 (Gamma), B.
1.
617.
2 (Delta) and B.
1.
1.
529 that appeared at that time (Omicron) all have ultra-high neutralizing activity, and the IC50 indexes of these strains reached 4 ng/mL, 5ng/mL, 3ng/mL, 6ng/mL and 5ng/mL
, respectively.

When tested with other subsequent mutant strains, including B.
1.
351-L242H, B.
1.
617.
1 (Kappa), C.
37 (Lambda), B.
1.
621 (Mu), etc.
, they maintained ultra-high neutralizing activity
.
IC50s of subsequent Omicron emerging offspring, such as BA.
1, BA.
2, BA.
2.
12.
1, BA.
3, BA.
4/5, were maintained at ultra-high levels of 4 ng/mL, 3 ng/mL, 3 ng/mL, 6 ng/mL and 5 ng/mL
.
The latest results show that XG005 still maintains a high degree of neutralizing efficacy
against BA.
5.
2 and BF.
7 mutant strains that are circulating in China.

In the face of the continuous mutation of the virus, the effectiveness of antibody drugs that have been marketed around the world has been greatly reduced, and the products of many pharmaceutical companies such as Eli Lilly, Regeneron, and GlaxoSmithKline have been stopped
because they are ineffective against mutant strains.

In the Boao Lecheng International Medical Tourism Pilot Zone in Hainan, the specially approved AstraZeneca antibody drug Evusheld (AZD7442/Ensade) has also significantly reduced its neutralizing efficacy on BA.
5 and offspring
.
Its neutralizing potency against BA.
4/5 has been reported to have decreased to 609 ng/mL
.

Among domestic manufacturers in China, only Tengsheng Boyao's long-acting new crown antibody drugs, ambavirumab and romisivimab combination therapy, were approved for emergency use
in China in July 2022.
According to relevant data, although it still maintained a certain neutralizing effect on Omicron mutant strains, it also showed a substantial decrease, and the IC50 for BA.
4/5 dropped to 2405 ng/mL
.

Globally, only Lilly's Bebtelovimab (LY-COV1404) antibody drug remains highly effective
against BA.
4/5.
However, the FDA has recently revoked its marketing authorization because it has lost its efficacy
in the latest mutant strain BQ.
1 in the United States.

The development progress of major new coronavirus antibody drugs at home and abroad is as follows:

▌ Ultra-conservative neutralizing epitope

XG005 has such a broad spectrum and efficient neutralizing potency that the neutralization epitope has attracted the attention
of researchers.
The researchers analyzed the sequence of the antibody and found that it could bind to the receptor-binding region (RBD) on the new coronavirus S protein, preventing the virus S protein from binding to the ACE2 receptor of human cells, thereby blocking the virus-infected cells
.

Sequence analysis revealed that three mutation sites (N440K, G446S, and N501Y) on the Omicron S protein were located on
the epitope of the XG005 antibody.
Cryo-EM structural analysis showed that these three binding sites did not significantly affect the binding
of XG005 to RBD.

While the N501Y mutation caused RBD and XG005 to lose two hydrogen bond bonds, the G446S mutation added two more hydrogen bonds between the two, while the N440K mutation reduced one hydrogen bond and added another
.
In addition, two salt bridges
were formed between Omicron RBD and XG005.
Therefore, these three mutations did not significantly attenuate the interaction between RBD and XG005, which still maintained a strong binding force
to all Omicron RBDs.

▌ Safer and longer effective

After confirming the highly effective neutralizing ability of XG005 and the conserved neutralizing epitope, the researchers began developing it as a drug
.
In cell experiments, the researchers found that XG005 interacts with the Fc receptor (FcR), which in turn induces antibody-mediated cell infection
.
Similar neutralizing antibodies, such as Eli Lilly's LY-CoV1404, have a similar phenomenon
.
In order to avoid possible ADE effects, the researchers engineered its FC end to reduce the interaction of FC regions with FcR and completely eliminate the potential ADE side effects
of XG005.

After ensuring the safety of the antibody, the researchers further carried out long-term modification of the antibody, greatly extending the half-life, and it is expected that the effective concentration in the body can be maintained for more than
half a year.
This means that the antibody may provide long-term protection to the subject for more than half a year, that is, there is a value
of long-term prevention.
Experimental data show that the modified antibody named XG005-CYLK has not significantly affected the neutralizing efficacy of the virus, and the researchers have developed it as a monoclonal antibody drug ADV2301 (XG005M), which is undergoing preclinical studies
.

Finally, the researchers tested the protective effect of XG005-CYLK antibody against true virus attack in mice, and experiments confirmed that whether it was BA.
2 or BA.
5, a single dose of XG005-CYLK antibody injection could significantly reduce the load of live virus in the lungs of mice, reducing by more than 1000 times, showing excellent antiviral effect
.

▌Passive immunization with high application value

The monoclonal antibody drugs currently developed against the new coronavirus mainly target the spike protein (S protein)
on the surface of the new coronavirus.
The S protein is equivalent to the key for the new coronavirus to enter the cell, and when the antibody drug binds to a specific site of the S protein, it can prevent the S protein from functioning, which is equivalent to blocking the channel
of the new coronavirus to enter human cells.
If the virus cannot enter the cell, it cannot reproduce and replicate, and will eventually be cleared
by the body's immune cells.
Therefore, antibody drugs can not only effectively treat new coronavirus infection, reduce viral load, prevent disease progression, but also play a role
in preventing infection.

As a tool for active immunization, vaccines are the most important means
of fighting infectious diseases.
However, the frequency of mutations of the new coronavirus is very high, and since 2022, Omicron has seen several waves of different mutant strains
such as BA.
1→BA.
2→BA.
5→ BF.
7/BQ1.
1/XBB.
Vaccines developed based on previous generations of strains have significantly reduced the preventive effect of antibodies that can induce human production
.
Moreover, the protective effect of existing vaccines can generally only be maintained for about half a year, and after half a year, the level of antibodies drops sharply, and the effect of the vaccine will be greatly reduced
.

Therefore, the artificial preparation of antibody drugs that can deal with various mutant strains in a broad spectrum has high medical application value
.
In addition to the active immunity of the vaccine, antibody drugs can add a layer of passive immunity protection
.
The use of antibody drugs in the general population after infection can accelerate symptom relief and shorten the time to turn negative; Use before and after virus exposure can avoid infection and ensure that work and life travel at critical times are not affected
.

In addition, there are a large number of vulnerable people in society, people who are not suitable for vaccination, and immunodeficient or immunocompromised individuals who cannot stimulate sufficient immune protection through vaccines, and such people can be passively immunized
with antibody drugs.
On the other hand, for high-risk groups who have been infected with the new coronavirus, such as the elderly, people with underlying diseases, immunodeficiency people, cancer patients, etc.
, timely injection of antibody drugs is expected to reduce the rate of severe disease and mortality
.

Dr.
Zhang Lunan, co-corresponding author of the paper and chairman of Ai Di Weixin Biopharmaceutical, said that the team is accelerating the push of this antibody drug to the clinical stage
.
It is planned to first conduct clinical studies on the therapeutic effect of volunteers infected with the new coronavirus in the dosage form of injection solution, and carry out clinical research
on virus infection prevention before exposure.
At the same time, dosage forms for nasal spray administration are also being developed
.

It is reported that nasal spray administration is a more convenient way to use, antibodies are administered to the respiratory mucosal system through spray, which can block the virus at the
first level of invasion.
The Wuhan Institute of Biological Products of China Biotechnology recently developed a nasal spray (F61) of a new coronavirus monoclonal antibody drug with a similar principle, which is also intended to have an immediate prevention effect
.
It is believed that antibody drugs, especially nasal spray administration, can provide us with new protection and treatment options, so that more ordinary people will be free from suffering from the new
crown virus infection in the subsequent epidemic season.

This article originates: Medicine Cube