Table of Contents
Abstract:
Coronaviruses are relatively large family of viruses (family Coronaviridae, subfamily Orthocoronavirinae), that has single stranded positive-sense RNA genome and a nucleocapsid of helical symmetry encapsulated in a membrane envelop. The COVID-19 causing novel SARS-CoV-2 is considered to be more contagious than MERS and SARS coronaviruses. Given the limited time to design a drug and escalating COVID-19 cases across the world, drug repurposing stands out as an effective tool.
It was in late December 2019, when a sudden surge of pneumonia like cases were reported in most hospitals in Wuhan city, China, particularly in patients who visited seafood market. 1 The disease was identified as COVID-19 (Corona Virus Disease 2019) caused by SARS-CoV-2 (Severe Acute Respiratory Syndrome-Corona Virus-2). Coronavirus being a zoonotic can be transmitted between animals to humans, in past, transmission of SARS-CoV (Severe Acute Respiratory Syndrome-Corona Virus) and MERS-CoV through animals (Middle East Respiratory Syndrome -Coronavirus) claimed many lives across the world. 2 Since its first case in China, COVID-19 is spreading like a wildfire across the globe claiming many lives. According to WHO, as of 31st March 2020, there are about 6,97,244 coronavirus cases reported across 204 countries with 33,257 confirmed deaths caused due to novel SARS-CoV-2 infection. WHO has announced worldwide pandemic of COVID-19, creating a dire need to stay careful through self-quarantine while maintaining hygiene and washing hands repeatedly.3 Although, SARS-CoV-2 can be transmitted through droplets of an infected person, some studies suggest systemic or fecal transmission of the virus in humans being possible.4 Another report suggests that SARS-CoV-2 virus can stay suspended in the air for 3 hours in the form of aerosol before dropping, while it can live on the surface of stainless steel and plastic for about 72 hours. 5 As per Ministry of Health, Government of India; India is reaching staggering numbers by day with 1,117 active cases and 32 deaths as of 31st March 2020 and counting. Therefore, it is imperative to analyze the scope of Coronavirus treatment.
Phylogenetics of Coronavirus
Coronaviruses are relatively large family of viruses (family Coronaviridae, subfamily Orthocoronavirinae), that has single stranded positive-sense RNA genome and a nucleocapsid of helical symmetry encapsulated in a membrane envelop. The viral membrane has glycoprotein spikes sticking out, giving a shape of crown or solar corona to the virus, hence the name (refer figure 1). There are four classes of coronaviruses entitled as alpha, beta, gamma and delta. So far, six types of coronaviruses have been identified. The novel SARS-CoV-2 along with SARS-CoV (severe acute respiratory syndrome-corona virus), MERS-CoV (Middle east respiratory syndrome-corona virus) belong to class beta-coronavirus. Between 2002-2004, SARS-CoV epidemic was seen in Asia, originating from China, while in 2012 the outbreak of MERS-CoV infection was first reported, that has spread to over 21 countries. 6 7 The COVID-19 causing novel SARS-CoV-2 is considered to be more contagious than MERS and SARS coronaviruses. 8 Symptoms of COVID-19 is similar to SARS and MERS in terms of causing pneumonia, however in some cases the SARS-CoV-2 may affect additional areas such as gastrointestinal tract, liver, kidney, brain etc. 9 10
Potential drug targets:
The glycosylated spike (S) protein on the surface membrane of betacoronavirus is known to induce immune response and initiate infection in host by binding to the host cell surface membrane protein called ACE-2 (angiotensin-converting enzyme 2). 11 12 The S protein of SARS-CoV-2 has been analyzed to have 10-20 times more binding affinity to ACE-2 protein of host cell, than SARS-CoV, making the former more contagious and highly infectious. 13 14 ACE-2 protein is expressed in lungs and gastrointestinal tract, explaining the viral infections in these areas. Nevertheless, for virus to attach to ACE-2 , the S glycoprotein of the virus needs to split, with assistance from human transmembrane protease serine-2 (TMPRSS-2) on the membrane , a phenomenon called S protein priming 12. One study found that the SARS-CoV-2 S glycoprotein harbours a furin cleavage site at the boundary between the S1/S2 subunits, which is processed during biogenesis and sets this virus apart from SARS-CoV and SARS-related CoVs. 15 SARS-CoV-2 also contains an exclusive potential cleavage site for furin protease. 16 The S glycoprotein must be cleaved by cell proteases to enable exposure of the fusion sequences and allow cell entry. This observation demonstrates that cleavage of the S glycoprotein is a barrier to zoonotic coronavirus transmission. 15. Another study reveals that virus entry into the human cells can also be interrupted by LY6E (Lymphocyte antigen 6E) which is known to hinder many coronaviruses including SARS-Cov-2 viral entry. 17 A recent study suggests SARS-CoV-2 enters the cell through endocytosis. 18. It further suggests that cathepsin L is essential for priming of SARS-CoV-2 S protein in lysosome for entry into cell.
Studying the interaction between novel SARS-CoV-2 with human surface membrane proteins can help in identifying the potential drug targets and designed effective drugs.
Drug Repurposing – treatment and prevention of COVID-19
Given the limited time to design a drug and escalating COVID-19 cases across the world, drug repurposing stands out as an effective tool. 19 Drug repurposing is a phenomenon of redeveloping an existing drug prescribed for a specific disease, to treat new diseases. Most of these drugs have been through the clinical testing phase and approved by FDA for use. Also, there is ample information available on their formulation, pharmacology etc. This approach is cost effective and has shorter developmental timelines. 20 There are various approaches to identifying a potential drug candidate for reprofiling, including data analysis and experimental methods.
The global medical emergency around COVID-19 has left several pharmaceutical and biotechnology companies working round the clock to develop an effective therapeutic agent for treatment. Phylogenetic analyses of 15 HCoV whole genomes revealed that novel SARS-CoV-2 shares highest sequence identity with SARS CoV. The nucleotide sequence similarity between SARS CoV and SARS CoV-2 was 79.7% with highest sequence identities to evolutionarily conserved, envelope and nucleocapsid proteins (96% and 89.6% sequence similarity respectively). 21 Recently, WHO through its global trial called “SOLIDARITY” has decided to look for treatment for COVID-19. Therefore, they are trying to repurpose drugs that are already approved for other diseases and known to be largely safe. WHO is also looking at unapproved drugs that have performed well in animal studies with the other two deadly corona viruses, SARS CoV and MERS CoV. 22
In this article, we have presented data on several patents filed both globally and locally for SARS and MERS. Note that SARS CoV-2 is a novel virus and therefore there is no data available on this so far. The drugs are categorized into small molecules and biologics. (Refer Table 1)
Small Molecules Drugs: They are the low molecular weight (less than 500kDa) organic compounds that regulate the biological process. They are chemically synthesized. Due to their small size, most of these drugs can pass through the cell membrane to reach their targets. Examples: Acids, phenolic compounds, lipids, amino acids, alkaloids, sugars, fatty acids. 23
Biologics: They are macromolecules (approximately more than 500kDa) that are synthesized in the living system or semi synthesized using microbial machinery. Most of these biopharmaceuticals are heat sensitive and susceptible to microbial contamination, which is why their manufacture needs extreme aseptic conditions. Examples: Sugars, Proteins, Peptides, Nucleic acids, viruses, vaccines, antibodies, etc. 24
Patents associated with betacoronaviruses (MERS and SARS)
According to a report by Technovigil, globally there are about 7333 patents filed for several coronaviruses till date, of which several patents are filed as potential drugs or vaccines for treating coronavirus infection,(refer table 1). Pfizer stood out as a major player among others in drug discovery, drug repurposing or vaccine synthesis as highlighted in Table 2. Note that these patents target SARS CoV and MERS CoV and not novel SARS CoV-2. 25 26
| S.No. | Type of Drug | Number of Patent applications |
|---|---|---|
| 1 | Biologics: | |
| Antibodies | 3131 | |
| Peptides | 3059 | |
| ds DNA viruses | 552 | |
| ss RNA | 1107 | |
| RT RNA | 328 | |
| 2 | Small Molecules: | |
| Active ingredients | 2240 |
Table 1: Patents filed globally for Coronaviruses (SARS, MERS) as of March 2020
| S.No. | Company | Number of Patent Applications |
|---|---|---|
| 1 | Pfizer | 396 |
| 2 | US NIH | 237 |
| 3 | GSK | 132 |
| 4 | Zoetis | 123 |
| 5 | Sanofi | 108 |
| 6 | Kineta Inc | 96 |
| 7 | Johnson & Johnson | 90 |
| 8 | Novartis | 85 |
| 9 | Merck | 81 |
| 10 | Pasteur Institute | 67 |
Table 2: Top global players in Coronavirus patent filing as of March 2020
Coronavirus Patents in India
Based on our search in Indian IPO site for patents on Coronavirus, we found over 30 patents, of which 6 patents were granted between 2010 to 2018. Most of these patents represent vaccines, drugs and diagnostics for treating SARS and MERS. Granted patents numbers are – 3704/CHENP/2011, 2003/CHENP/2007, 236/CHENP/2006, 243/CHENP/2006, 866/CHENP/2008, 912/CHENP/2006.
| S.No. | Drug containing | Number of Patent applications |
|---|---|---|
| 1 | Vaccine | 2 |
| 2 | Antibodies | 5 |
| 3 | Small molecules | 7 |
| 4 | Peptides/protein | 6 |
| 5 | Nucleic acid | 4 |
| 6 | Nanoparticles | 1 |
Table 3: Coronavirus (SARS and MERS) patents filed in India as of March 2020
Recommendations by WHO:
The WHO has recently suggested four most promising drugs for treating COVID-19 (refer Figure 3) – Remdesivir, an experimental antiviral drug that stops replication by inhibiting RNA dependent RNA polymerase (originally designed to treat Ebola) by Gilead Science Inc. (US20170071964A1); Chloroquine and hydroxychloroquine, an anti-malarial drug which is said to incur anti-viral properties; combination of lopinavir and ritonavir, two HIV drugs that is known to inhibit protease, and combination of interferon-beta (inflammation regulator) with lopinavir and ritonavir. 22 The antiviral effects of Chloroquine was first described by a group in Italy. 27 Overdose of Chloroquine and Hydroxychloroquine can cause lethal side effects. A study in France on 42 patients proved hydroxychloroquine along with Azithromycin as an effective treatment. 28 India has several granted patents for lopinavir and ritonavir, Chloroquine and hydroxychloroquine, Remdesivir which can be used as for drug repurposing trials.
| Active ingredient | Number of patents | Application number and assignees |
|---|---|---|
| Chloroquine | 4 | 263/DEL/2012 : CSIR 3407/KOLNP/2007 : State of Oregano through State board of higher education on behalf of Portland state university 3803/DELNP/2005 : Jarrow Formulas, Inc. 501/MUM/2000 : Nicholas Piramal India Ltd. |
| Hydroxychloroquine | 2 | 1213/MUM/2003 : M/S. IPCA Laboratories Ltd. 3803/DELNP/2005 : Jarrow Formulas, Inc. |
| Lopinavir | 3 | 512/MUMNP/2014 : University of Liverpool 496/MUM/2008: Macleods Pharmaceuticals Ltd. 1184/CHE/2007 : Aurobindo Pharma Ltd. |
| Ritonavir | 5 | 496/MUM/2008: Macleods Pharmaceuticals Ltd. 1184/CHE/2007 : Aurobindo Pharma Ltd. 354/MUMNP/2010: Stichting Het Nederlands Kander Instituut, Slotervaart Participaties BV 226/DELNP/2008 : Janssen Sciences Ireland UC 699/MUMNP/2004: Cristalia productos quimicos farmaceuticos Ltd. |
| Remdesivir | 3 | 1328/CHENP/2013: Gilead Sciences Inc. 7068/DELNP/2010: Gilead Sciences Inc. 201948034308: Gilead Sciences Inc. |
Table 4: Indian patent data on repurposed drugs for COVID-19
Other Potential Therapeutic Agents:
Besides the WHO recommendations, there are several other potential biologics particularly monoclonal antibodies to target specific virus, are being designed by several groups. Vir Biotechnology, US has made antibodies useful for diagnosis of COVID-19. While Regeneron has designed similar antibodies. 29 An antibody called Tocilizumab, an immunosuppressant originally used for treating Rheumatoid arthritis is already used for treating COVID-19 patients in China which seems to be highly effective as per a small study on 19 people. 30
Using artificial intelligence, a group at Imperial College, London has arrived at a Rheumatoid arthritis drug Baricitinib as a potential drug for COVID-19 31. Recently, the 3D structure of main protease of SARS-CoV-2 has been solved, this enzyme can possibly serve as a potential drug candidate for COVID-19 treatment. 32
Conclusion:
With more and more patients succumbing to the disease and global economy plummeting drastically to record low, having a sure shot medicine and vaccine for SARS-CoV-2 is the only hope. While scientists and medical professionals are working tirelessly to save the situation, we as individuals have our chance to control the community spread of this deadly virus by staying home and practicing hygiene.
Stay Home. Stay Safe.
Sai Ratna Manjari
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