Rega Compound 17 & Compound A - Potential Cures for Chronic Coxsackie B

[Jesse2233]

Hey everyone,

I've briefly referenced Rega Compound 17 & Compound A as two new drugs Dr John Chia has mentioned as potential cures for chronic Coxsackie B infections (which have been linked to the development of ME/CFS for decades, and may be an ongoing causal factor driving chronicity).

Dr Chia has spoken to the teams developing both of these antivirals and let them know how large their potential market is. As a result they have ramped up personnel and resources committed to these projects.

I thought it would be good to consolidate what we know about these two antivirals into one thread that we can update as we learn more.

Dr Chia's comments as relayed by @Never Give Up:

He also said that the two drug companies working on anti EV meds are making progress and that both now know what a huge market they have, before they thought they were going after a market of about 200,000 kids per year with EV in the brain. They have recently increased the size of their teams working on these drugs. He mentioned that the anti hep C meds are so smart that they wake the virus up, make it come out of hiding and then kill it. Five years ago nobody thought it was possible to get rid of hep C and now we can, or at least get rid of enough of it that the immune system can easily take care of what remains. He sees a similar future for EV infections.

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More detailed information:

Compound 17 is a novel benzene sulfonamide derivative that was shown to inhibit the in vitro replication of CVB3, CVB4, CVB5 and CVB6. It's being developed by Dr Rana Abdelnabi, a molecular biologist and virologist, at the Rega Institute in Leuven, Belgium.

From the 19th International Picornavirus Meeting last year in Switzerland (pg 140):

OBJECTIVES:

An in silico molecular docking study on the Coxsackievirus B3 (CVB3) 3C-protease guided the synthesis of a novel benzene sulfonamide derivative (i.e. compound 17) that was shown to inhibit the in vitro replication of CVB3. Our aim was to use virus-cell-based assays to confirm the 3C-protease as a target for the compound and to study the particular characteristics of its antiviral activity.

METHODS:
Cell-based antiviral assays (CPE-reduction, virus yield and plaque assays) and molecular biology
tools (reverse-engineering, RT-PCR and sequencing).

RESULTS:
Compound 17 proved to inhibit the in vitro replication of CVB3 (strain Nancy) as well as of CVB1,
CVB4, CVB5 and CVB6 with EC50 values ranging between (0.7-37) μM. Surprisingly, the compound did not show any antiviral activity against CVB2 and other viruses from different enteroviruses groups. In contrast to what is expected for a protease inhibitor, a time-of-drug-addition study pointed out that compound 17 interfered with an early step in the CVB3 replication cycle. A thermo-stability assay provided an additional indication of an
interaction between compound 17 and the CVB3 virus particle. This latter mechanism of action was confirmed
by the genotyping of independently selected compound 17-resistant CVB3 variants, which all carried mutations
in the VP1 gene (F76C, E78G, A98V and D133G). Compared to the wild-type (WT), the reverse-engineered VP1 F76C, E78G, A98V and D133G mutants proved to be 18, 21, 3 and 38-fold less sensitive to the antiviral effect of compound 17, respectively. Interestingly, the mutated VP1 residues are located outside the common drug-binding pocket for capsid binders such as pleconaril. Moreover, the D133 residues of all five VP1 units are arranged in the form of ion channel at the 5-fold axis. Plaque phenotyping revealed that the VP1 F76C, E78G and D133G mutations resulted in a smaller plaque size than WT.

CONCLUSION:

Compound 17, originally designed in silico to inhibit the viral 3C-protease, is a potent inhibitor of CVB3 replication. Surprisingly, study of the mechanism of action revealed that the compound is a capsid binder with an entirely new target on the virus particle. Further experiments are ongoing to explore the precise mechanism
by which compound 17 interacts with CVB3 capsid and to develop more potent and broader-spectrum analogs.

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Compound A a proprietary 2C-targeting enterovirus inhibitor that was shown to completely erradicate CVB4 from the tissue / organs of mice without causing major side effects. It's being developed by Dr Els Scheers, another virologist, also at the Rega Institute in Leuven, Belgium.

From the same conference mentioned above, pg 139:

OBJECTIVES:
We report the development of a relevant enterovirus mouse infection model that is ideally suited to (i) assess the antiviral efficacy of enterovirus inhibitors and (ii) monitor the possible in vivo development of antiviral drug-resistance.

METHODS:
SCID mice were infected intraperitoneally (ip) with 10^5 TCID 50 Coxsackievirus B4 (CVB4) and weight loss
was monitored as a symptom of disease. CVB4 RNA and infectious particles in serum and organs were quantified by means of qRT-PCR and end-point titration respectively. Viral RNA was genotyped by Sanger sequencing.

RESULTS:
As of day 3 post infection (dpi), weight loss was observed in infected mice which all had to be
euthanized at 5 dpi. High viral RNA titers (~10 9 genome equivalents (GE)/100mg tissue) were detected in the
pancreas. Titers in heart, lung, liver, spleen and brain were ~10^6 -10^7 GE/100mg tissue. High titers of both viral RNA (10^9 GE/mL) and infectious particles (10^6 TCID 50/ml) were detected in serum. To explore whether this model can be used to assess the efficacy of antiviral compounds, the effect of compound A (a proprietary 2C-targeting enterovirus inhibitor) was studied. CVB4-infected mice were treated for either 5 or 12 consecutive days with twice daily (BID) dosing of 20 mg/kg. After stop of treatment, the mice remained healthy until the end of the experiment (60 dpi) and no virus was detectable in serum or pancreas. Next, infected mice were treated with suboptimal regimens: either 20 mg/kg once daily during 15 consecutive days or 20 mg/kg once daily during 20 consecutive days (treatment was initiated at day of infection). The mortality rate of both groups was 40% and the mean day of death 45 ± 12 dpi and 48 ± 10 dpi respectively. The 60% of mice that survived were euthanized at 77 dpi; no virus was detectable in serum or organs indicating that they were cured from infection. To assess whether the (delayed) mortality in the 40% of mice was due to the emergence of drug-resistant variants, viral RNA was isolated from serum, heart and pancreas and the 2C gene was sequenced. Interestingly, in nearly all samples one substitution i.e. 2C_A239T/V was identified. This mutation did not result in a reduced sensitivity to the inhibitor as assessed in vitro and in mice that had been inoculated with these variants. Full genome sequencing revealed the presence of additional mutations in the viral genome for which it is being explored whether these, and the 2C_A239T/V, represent mouse adaptive mutations.

CONCLUSIONS:
We developed a robust CVB4-infection mouse model to assess the in vivo efficacy of novel antiviral agents. We demonstrate that a potent antiviral agent is able to cure immunodeficient mice from this aggressive enterovirus infection. It was next explored whether suboptimal dosing (that delays but does not prevent mortality of all infected mice) may lead to the selection of drug-resistant variants. For this particular inhibitor, no drug-resistant variants developed. This CVB4/CID model provides a powerful tool to study population dynamics over time in the presence or absence of antiviral pressure in the infected host

 

[Jesse2233]

I found out a bit more...

The person heading the project and the lab is Dr Johan Neyts, a virologist and professor. We are in good hands. Dr Neyts has connections with the drug companies Novartis and Gilead and has drugs in trial with them. He's authored over 200 research papers, given 85 lectures, and holds several anti-viral patents.

A bit about what he's written on Compound A:

We are working hard towards developing drugs that may be used to treat this condition [...] I can not make any promises at this time except that we, and our colleagues involved, are working as hard and diligently as possible.

More on Dr Neyts:

Johan Neyts is full professor of virology at the University of Leuven, Belgium. His research is focused on the development of novel antiviral strategies against a number of viruses including picornaviruses, flaviviruses and HCV. His laboratory has also a long standing expertise with respect to the development of small animal models for flavivirus infections and with the molecular virology of flaviviruses. His team discovered together with Debiopharm (Lausanne) the anti-HCV activity of Debio-025, a compound which is now in clinical development by Novartis. Together with Prof. Gerhard Puerstinger (University of Innsbruck, Austria) he discovered a novel class of HCV inhibitors, of which the potent compound GS 9190 is now in phase II clinical development at Gilead Sciences (Foster City, CA, USA) under a license agreement with the University of Leuven. He is inventor on a number of patents in the antiviral field.

His work has been published in several book chapters and in more than 200 papers in international scientific journals. He is on the editorial board of the journals ‘Antiviral Research’ and ‘Antiviral Chemistry and Chemotherapy’,ad hocreviewer for about 30 scientific journals, member of several national and international scientific committees and on the board of directors of the International Society for Antiviral Research. He is the Chief Scientific Officer and co-founder of the spin-out company Okapi Sciences NV. Over the last couple of years he has given about 85 invited lectures. He teaches medical virology at the school of dentistry and the school of medicine at the University of Leuven. He has been honoured with a number of awards including from the Royal Belgian Academy of Medicine, the Belgian Fund for Scientific Research and the International Society for Antiviral Research.

The Neyts lab is/was partner in four large EU funded consortia, i.e. a “Network of Excellence”,VIRGILon antiviral drug resistance, an “Integrated Project”VIZIERon the replication machinery of RNA viruses as targets to inhibit viral replication, a specific targeted project “Dengframe” to identify strategies to control dengue and the “Coordinated Action”RiviGeneon highly pathogenic viruses. Johan Neyts is the coordinator of a large NIAID/NIH funded project on poxvirus inhibitors and a large project on dengue drug discovery funded by the Welcome Trust.

Some interesting papers from Dr Neyts:

• Synthesis of novel purine-based coxsackievirus inhibitors bearing polycylic substituents at the N-9 position.Archiv der Pharmazie.vol.347 (7), pp. 478-85
  
  
• Fitness and virulence of a Coxsackievirus mutant that can circumnavigate the need for phosphatidylinositol 4-kinase class III beta. Journal of Virology.vol.88 (5), pp. 3048-51
  
  
• SAR studies of 9-norbornylpurines as Coxsackievirus B3 inhibitors.Bioorganic & Medicinal Chemistry Letters.vol.21 (14), pp. 4271-4275

 

[alex3619]

I was positive for CVB3 antibodies when I was first diagnosed with CFS (though I prefer an ME label now). Anything that works, and has no or rare extreme side effects, would be welcome.

 

[Hip]

I was positive for CVB3 antibodies when I was first diagnosed with CFS (though I prefer an ME label now). Anything that works, and has no or rare extreme side effects, would be welcome.

Did you see the idea of using interferon suppositories for treating enterovirus? The advantage of these is that they are infinitely cheaper than interferon injections, and also, they don't create anti-interferon antibodies like interferon injections can. Some info in this post.

 

[frozenborderline]

Very excited about this. In the meantime oxymatrine, although hopefully I don’t have any autoimmunity it may worsen (possibly that’s overhyped as a problems tho ?)

 

[daneck]

Are there any updates on these antiviral drugs?

 

[Hip]

Are there any updates on these antiviral drugs?

I wrote to several people at the Rega Institute asking about the progress of these drugs, but got no replies.

But I understand that these drugs have now been given priority development at Rega due to the fact that Dr John Chia made Rega aware of the number of diseases which involve chronic enterovirus, which includes ME/CFS, T1D, dilated cardiomyopathy, and others.

 

[Stressed85]

Do we think these may help the Chinese virus

 

[Hip]

Do we think these may help the Chinese virus

These new antivirals, which should be available in a year or two, target coxsackievirus B, and may be very effective for ME/CFS linked to coxsackievirus B.



They will likely only help the Chinese virus if that virus is a type of coxsackievirus B.

 

[Hip]

There is a newly published paper on the mechanism of action of Rega Compound 17 on coxsackievirus B.

The paper says compound 17 is benzene sulfonamide derivative, and is a potent inhibitor of CVB3, and also inhibits CVB1 and CVB6, and exerts moderate antiviral activity against CVB4, CVB5. It has no antiviral activity against CVB2 however.


An article on compound 17:
A surface crater in viruses may be key to keeping colds from spreading


Basically, compound 17 sits in the surface crater found on coxsackievirus B, and this thwarts the virus. The paper says:

These compounds fit in a hydrophobic pocket in the viral particle, thereby preventing binding of the virus to the receptor and/or uncoating

There are several Rega compounds effective against enteroviruses:

Rega compound 1 and 2 — Compound 1 inhibited all tested enteroviruses and rhinoviruses in vitro, including CVB3, echovirus 9 & 11. Compound 2 (which is similar to 1) was tested in mice against CVB4 infection, and reduced viral levels by 100-fold. Chemical structure known. Ref: here.

Rega Compound 12 — Inhibits CVB3 in vitro. Chemical structure known: 4-dimethylamino benzoic acid. Ref: here.

Rega Compound 17 — Inhibits CVB1 to CVB6 in vitro, except does not work for CVB2. Chemical structure known. Ref: here.

Rega Compound A — Potently eliminated CVB4 infection from mice in the study. Chemical structure I could not find, but it is an enterovirus 2C protein inhibitor. Ref: here.

 

[JinZ]

"Similar to pleconaril, compound 17 was found to target CVB3 replication at an early stage of the viral cycle because most of the antiviral activity was lost when the compound was added 2 h postinfection."

Does this mean it is not useful for post infection ?

 

[Hip]

"Similar to pleconaril, compound 17 was found to target CVB3 replication at an early stage of the viral cycle because most of the antiviral activity was lost when the compound was added 2 h postinfection." Does this mean it is not useful for post infection ?

No, with in vitro experiments in a cell line, they will often compare the efficacy of an antiviral when added before the virus is introduced to the cells, to the efficacy when the antiviral is added after the virus is introduced.

By comparing these two efficacies, it enables the researchers to determine whether the antiviral interferes will an early stage of the viral lifecycle (such as attaching to the cell, or cellular entry), or a later stage (such as viral replication within the cell).

So their experiment showed that compound 17 interferes with an early stage of the viral lifecycle.

In clinical infections, the viral lifecycle will go through all its stages, so this should still work for chronic established infections.

 

[Sidny]

Very promising information thanks for posting Hip!. It’s incredible that even in something as complex as virology if researchers focus their efforts on understanding and creating treatments for viruses, there’s a lot that can be done to slow them down or even cure them!

 

[Pyrrhus]

So their experiment showed that compound 17 interferes with an early stage of the viral lifecycle.

In clinical infections, the viral lifecycle will go through all its stages, so this should still work for chronic established infections.

Unfortunately, capsid inhibitors such as pleconaril (and apparently compound 17) are only effective in the acute phase of the enteroviral infection, when the virus uses capsids to move between cells. In the persistent phase of the infection, the virus bypasses the capsid stage and uses other means to move between cells. Generally speaking, capsid inhibitors seem great during in vitro testing, but usually fall flat during in vivo testing.

But compound 17 could still yet turn out to be effective for the common cold. (Acute rhinovirus infections) And that is probably what the pharma execs would target it for.

 

[Hip]

Unfortunately, capsid inhibitors such as pleconaril (and apparently compound 17) are only effective in the acute phase of the enteroviral infection, when the virus uses capsids to move between cells. In the persistent phase of the infection, the virus bypasses the capsid stage and uses other means to move between cells. Generally speaking, capsid inhibitors seem great during in vitro testing, but usually fall flat during in vivo testing.

It is thought (but as far as I am aware not proven) that chronic non-cytolytic enterovirus may be able to move from cell-to-cell by 3 additional means other than just viral capsids:

In persistently infected cultures, virus transmission may occur through the release of extracellular vesicles, formation of cell protrusions and intercellular bridges

Source: here

I started a thread on the cellular protrusion mechanism here (there's a fascinating video showing cellular protrusions moving in real time).


But spread of chronic non-cytolytic enterovirus infection still occurs via capsids too. So Rega Compound 17 should inhibit that aspect of non-cytolytic enterovirus spread.

Dr John Chia is excited about the treatment possibilities of these new Rega Institute antivirals for ME/CFS, and so presumably thinks they may help enterovirus ME/CFS patients.

I remember reading somewhere that Dr Chia was instrumental in getting these Rega drugs fast tracked to market, because he made the pharmaceutical companies aware that chronic enterovirus is involved in several diseases, and thus these anti-enteroviral drugs would have a good market. Apparently pharmaceutical companies were oblivious to the fact that enterovirus was involved in chronic diseases.

 

[Pyrrhus]

But spread of chronic non-cytolytic enterovirus infection still occurs via capsids too. So Rega Compound 17 should inhibit that aspect of non-cytolytic enterovirus spread.

Good point. To support your point, we need look no further than this ME patient's experience with the capsid inhibitor pleconaril:
http://web.archive.org/web/20190602051945/http://enteroviruses.com/abouttheauthor.html

She found that her enteroviral antibodies dropped when she started pleconaril. Then the pleconaril stopped working and her antibodies rose again. Although she attributed this drug failure to "limited availability, as well as the dosing regimen", capsid inhibitors are also notorious for eliciting drug resistance mutations in the virus, as highlighted by Neyts in the recent paper you cited.

I started a thread on the cellular protrusion mechanism here (there's a fascinating video showing cellular protrusions moving in real time).

I know, that paper blows my mind every time I read it. It's one of those things that I might not believe if I didn't see the video with my own eyes. We still have no idea how the intercellular bridges occur. To what extent is the enterovirus co-opting a host program for intercellular transport? To what extent is the intercellular transport encoded in the few proteins that the enterovirus produces? So many fascinating questions.

 

[Pyrrhus]

Source: here

By the way, this source also describes the isolation of poliovirus in patients with post-polio syndrome, a syndrome indistinguishable from ME. So this study equally implies the persistence of both type B and type C enteroviruses. (Multiple caveats apply.)

Although the first reports on post-polio syndrome claimed that the symptoms of post-polio syndrome do not become apparent until 10-20 years after poliovirus infection, they really meant that the symptoms do not become apparent to doctors until 10-20 years after poliovirus infection. The medical community refused to recognize post-polio syndrome for decades.

 

[Hip]

Good point. To support your point, we need look no further than this ME patient's experience with the capsid inhibitor pleconaril:
http://enteroviruses.com/abouttheauthor.html

That's an interesting find on pleconaril treatment.

One of Dr Chia's papers also documents his brief tests with pleconaril on 4 enterovirus ME/CFS patients, which seemed rather lackluster (only 1 out 4 patients tested responded, and only modestly).

Though table 1 of a study shows the potency of pleconaril against CVB and echovirus varies enormously from one serotype to another, and even from one strain of CVB to another, being highly potent for some serotypes/strains, and very weak for others. So depending on what serotype or strain you have, pleconaril may or may not help. But of course pleconaril is not going to be brought to market.

capsid inhibitors are also notorious for eliciting drug resistance mutations in the virus

I read somewhere in the last few days that the crater or pocket on the viral capsid which Rega Compound 17 locks into is crucially important in the lifecycle of the virus, and thus this is expected to prevent drug resistance mutations from arising, because any genetic variation of the pocket shape would likely cause the viral lifecycle to fail.

I can't remember where I read that, due to my increasingly sieve-like memory, but might have been the Neyts paper.

 

[JinZ]

"But of course pleconaril is not going to be brought to market."

Any specific reason why not?

 

[Hip]

"But of course pleconaril is not going to be brought to market."

Any specific reason why not?

This paper says drug resistance was a concern:

Pleconaril, a promising drug candidate that inhibits virus attachment by binding to the viral coat protein, has been dropped from further clinical development because of concerns about viral resistance and side effects in patients