Tackling Coronavirus with WP1122
The Short Version
- Viruses (like SARS-CoV-2) depend on glycolysis and glycosylation for infectivity and replication.
- Glycolysis and glycosylation can be disrupted by using a glucose decoy known as 2-DG.
- And, while 2-DG has been shown to be effective in vitro, 2-DG’s lack of drug-like properties makes it ineffective as a drug in humans.
- WP1122 has the potential to solve 2-DG’s problem by creating a prodrug of 2-DG that reaches much higher tissue/organ concentrations than 2-DG alone.
- We are moving as quickly as possible to prepare WP1122 for clinical evaluation in the treatment of COVID-19. Based on guidance from the FDA, we believe that we need to demonstrate efficacy in a COVID-19 animal model in order to proceed with COVID-19 clinical trials in the US. Therefore, the timing of any such clinical trial activity in the US is subject to the limited access we have to validated in vivo efficacy testing.
- We caution readers that to date all of our data has been preclinical in nature.
The Slightly Longer Version
Moleculin has a unique opportunity to contribute to the global challenge posed by coronavirus and other viruses threatening our communities. We announced a collaboration with a major Texas university institution to evaluate our drug candidate, WP1122, and its analogs and this has now been followed by collaborations with additional players who bring the needed expertise to fully develop this new potential treatment for diseases like COVID-19.
Independent researchers at the Institute of Biochemistry II – Goethe-Universität Frankfurt in Germany announced their discovery that 2-DG, the active compound in WP1122, reduced in vitro replication of SARS-CoV-2 by 100%.
Based on preclinical data, we have reason to believe that WP1122 may be effective against COVID-19. This is based on the vital roles that glucose plays in the proliferation of SARS-CoV-2. Viruses like SARS-CoV-2 place increased demand on glucose and upregulate their host cell’s metabolic processes. Some of the most important of these processes are believed to be glycolysis and glycosylation.
Glucose provides energy in the form of adenosine triphosphate (ATP) to viral host cells via glycolysis, as well as enabling glycan formation supporting creation of glycoproteins during glycosylation.
Understanding this is the key to understanding why WP1122 may represent a potential treatment. Glycolysis and glycosylation sound similar, but they are very different, even though they rely on the same base material, glucose, which is essentially sugar. In highly simplified terms, glycolysis converts glucose into fuel and glycosylation uses glucose to help build important protein structures that enable the way our cells function with each other and respond to changes in their environment. When viruses like SARS-CoV-2 invade our cells, they coopt these processes to increase both their infectivity and their replication.
Enveloped viruses depend on glycosylation, which begins by hijacking the host cell secretory pathway, where combinations of sugar molecules (including glucose and mannose) called “glycans” are combined with proteins, as “folding” provides 3-dimensional structure. These viral “glycoproteins” mediate the assembly and budding of new virions. The host’s immune system can be evaded through “shedding” of these glycoproteins (*for some viruses, not yet confirmed for coronaviruses) and through “glycan shielding.” Glycans are crucial for viral attachment and infection of host cells.1
Most of us are now familiar with the physical appearance of the spikes forming the corona around the coronavirus that gives it its name. These spikes are called glycoproteins and they play a vital role in the ability of coronavirus to infect host cells and to replicate.1 They also form a kind of camouflage that protects the virus from our immune systems. Like the name implies, a glycoprotein is the combination of glycans (see explanation in figure above) with proteins and the process of forming glycoproteins within the host cell is called glycosylation. Without proper glycosylation, viruses like the coronavirus cannot survive.
The role of glycosylation in viruses is widely discussed, but less so glycolysis. Glycolysis is the process by which cells convert glucose into energy. A recent study demonstrated that viruses induce an anabolic state in their host cells, which causes these infected cells to upregulate their production of energy using glycolysis as compared with their healthy neighbors.2
Viruses induce an anabolic state in host cells, which in turn makes them highly dependent upon glycolysis for adequate energy production. 2, 3
Given the roles of both glycosylation and glycolysis, it becomes apparent why glucose is critically important to the coronavirus. Given how important glucose is to these vital processes, one potential strategy for attacking viruses is to use their dependence upon glucose against them. And, this is where 2-DG potentially comes in. 2-DG stands for 2-Deoxy-D-Glucose and it is referred to as a glucose decoy. To cells, 2-DG looks like glucose, but it has one of the hydroxyl groups (the OH symbol shown here in red) found in the chemical structure of natural glucose removed. This missing hydroxyl group is just enough of a change that 2-DG won’t actually convert into energy or support proper glycosylation.
2-DG appears to the body to be natural glucose, but its lack of one hydroxyl group (shown in red on D-Glucose above) means that 2-DG will not convert into energy via glycolysis and it will not form the proper building-blocks for glycan formation during glycosylation.
Importantly, multiple independent studies have shown the disruption of both glycolysis and glycosylation, can have a potent effect against viruses like coronavirus.2, 3, 4, 5, 6, 7 This was, in fact, demonstrated in vitro in a range of viruses. These include rhinovirus, herpes and others, as well as porcine epidemic diarrhea virus, which is another coronavirus.
Researchers in Frankfurt, Germany, demonstrated the effect 2-DG has on SARS-CoV-2. In an unreviewed article submitted to NatureResearch (https://www.researchsquare.com/article/rs-17218/v1) by Bojkova, D et al (March 11, 2020; DOI: 10.21203/rs.3.rs-17218/v1), the authors reported that blocking glycolysis with non-toxic concentrations of 2-DG completely prevented SARS-CoV–2 replication in human cells (graph shown here). This is a significant milestone and we believe it supports an aggressive effort to pursue the use of 2-DG in clinical trials.
Effect of in vitro incubation of non-cytotoxic levels of 2-DG in Caco-2 cells on viral replication of SARS-CoV-2.
Fortunately, there is already a lot of clinical data supporting the safety and tolerability of 2-DG in humans. 8,9,10,11,12,13,14 But there is a problem with 2-DG. The problem is that its capability in vitro does not translate well into animals and humans. This is because 2-DG lacks what we call “drug-like properties.” It is too rapidly metabolized, and it fails to reach the necessary concentration levels in tissue and organs. Essentially, it hasn’t been possible to get enough 2-DG into a patient and taken up by the critical tissue and organs in enough concentration in order to stop viruses.
Our scientific founder, Dr. Waldemar Priebe, Professor of Medicinal Chemistry at MD Anderson Cancer Center, discovered a way to dramatically improve the drug-like properties of 2-DG. He did this by creating a prodrug of 2-DG that greatly improved its drug-like properties.
The presence of two acetyl groups (shown in blue) in WP1122 forms esters with hydroxyl groups at positions C-3 and C-6 and greatly enhances its tissue/organ uptake and retention.
So, what is a “prodrug?” A prodrug is a medication or compound that, after administration, is metabolized (meaning it is converted within the body) into a pharmacologically active drug. In the case of WP1122, chemical modification of 2-DG creates a molecule that, after being administered, is transformed by normal metabolic processes into the active agent, which in this case, is 2-DG. In short, 2-DG is the active fragment of WP1122. In chemical terms, it’s referred to as the active moiety (or, subpart) of WP1122.
And, in fact, when we compare WP1122 to 2-DG alone in vivo, we see much higher concentrations of 2-DG in tissue and organs when that 2-DG is delivered by WP1122.15 Supplying 2-DG via WP1122 nearly doubles its half-life and almost triples its peak concentration in plasma. But where we see the biggest improvement is in organ uptake and potency. Until the advent of COVID-19, the bulk of our development work has been in the area of cancer treatment and depending on the tumor model, we’ve seen as much as 10 times the level of potency from equimolar doses of WP1122 when compared with 2-DG alone.
With the most recent in vitro demonstration that 2-DG is effective in vitro against SARS-CoV-2, we now believe that WP1122 could represent a potential therapy for COVID-19 and other viral diseases. Our goal is to have WP1122 in a clinical trial in 2021. Please watch our news flow for updates on this critical project.
 Bagdonaite I., et al. Global aspects of viral glycosylation. Glycobiology. 2018, vol. 28, no. 7, 443–467 doi: 10.1093/glycob/cwy021.
 Gualdoni G., et al. Rhinovirus induces an anabolic reprogramming in host cell metabolism essential for viral replication. PNAS. 2018, E7158–E7165, vol. 115, no. 30.
 Fontaine K., et al. Dengue Virus Induces and Requires Glycolysis for Optimal Replication. Journal of Virology Jan 2015, 89 (4) 2358-2366. DOI: 10.1128/JVI.02309-14.
 Schmidt M. et al. Interference of Nucleoside Diphosphate Derivatives of 2-Deoxy-D-glucose with the Glycosylation of Virus-Specific Glycoproteins in vivo. Eur. J. Biochem. 70, 55-62 (1976).
 Leung H. J., Duran, E. M., Kurtoglu, M., Andreansky, S., Lampidis, T. J., et al. (2012) Activation of the unfolded protein response by 2-deoxy-D-glucose inhibits kaposi’s sarcoma-associated herpesvirus replication and gene expression. Antimicrob. Agents Chemother. 56, 5794–5803.
 Maehama, T., Patzelt, A., Lengert, M., Hutter, K. J., Kanazawa, K., et al. (1998) Selective down-regulation of human papillomavirus transcription by 2-deoxyglucose. Int. J. Cancer. 76, 639–646.
 Wang Y., et al. Triggering unfolded protein response by 2-Deoxy-D-glucose inhibits porcine epidemic diarrhea virus propagation. Antiviral Research 106 (2014) 33–41.
 Raez L.E., et al. “A phase I dose-escalation trial of 2-deoxy-D-glucose alone or combined with docetaxel in patients with advanced solid tumors.” Cancer Chemother Pharmacol. 2013 Feb;71(2):523-30. doi: 10.1007/s00280-012-2045-1.
 Laszalo J, et al. “The effect of 2-DG infusions on lipid and carbohydrate metabolism in man.” J Clin Invest 1960;40:171-6.
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 Mohanti BK, et al. “Improving cancer radiotherapy with 2-deoxy-D-glucose: phase I/II clinical trials on human cerebral gliomas.” Int J Radiat Oncol Biol Phys. 1996 Apr 1;35(1):103-11.
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 Murugesan K, et al. “Phase I trial of 2-deoxyglucose for treatment of advanced solid tumors and hormone refractory prostate cancer: A pharmacokinetics (PK) assessment.” Proceedings: AACR 101st Annual Meeting 2010‐‐ Apr 17‐21, 2010; Washington, DC.
 Stein M, et al. “Targeting tumor metabolism with 2-deoxyglucose in patients with castrate-resistant prostate cancer and advanced malignancies.” Prostate. 2010 Sep 15;70(13):1388-94.
 Zielinski R, et al. “Preclinical evaluation of WP1122, a 2-DG prodrug and inhibitor of glycolysis.” Proceedings: Symposia on Cancer Research 2017 Cancer Metabolism, Houston, TX, 10/2017.