Retooling a COVID drug to boost its effectiveness

Coronavirus particles, illustration.

When the COVID-19 pandemic broke out scientists scrambled to find existing medications that might help counter the life-threatening elements of the virus. One of the first medications that showed real promise was remdesivir. It’s an anti-viral drug that was originally developed to target novel, emerging viruses, viruses like COVID19. It was approved for use by the Food and Drug Administration (FDA) in October 2020.

Remdesivir showed real benefits for some patients, reducing recovery time for those in the hospital, but it also had problems. It had to be delivered intravenously, meaning it could only be used in a hospital setting. And it was toxic if given in too high a dose.

In a new study – partially funded by CIRM (DISC2 COVID19-12022 $228,229) – researchers at the University of California San Diego (UCSD) found that by modifying some aspects of remdesivir they were able to make it easier to take and less toxic.

In a news release about the work Dr. Robert Schooley, a first author on the study, says we still need medications like this.

“Although vaccine development has had a major impact on the epidemic, COVID-19 has continued to spread and cause disease — especially among the unvaccinated. With the evolution of more transmissible viral variants, breakthrough cases of COVID are being seen, some of which can be severe in those with underlying conditions. The need for effective, well-tolerated antiviral drugs that can be given to patents at high risk for severe disease at early stages of the illness remains high.”

To be effective remdesivir must be activated by several enzymes in the body. It’s a complex process and explains why the drug is beneficial for some areas, such as the lung, but can be toxic to other areas, such as the liver. So, the researchers set out to overcome those problems.

The team created what are called lipid prodrugs, these are compounds that do not dissolve in water and are used to improve how a drug interacts with cells or other elements; they are often used to reduce the bad side effects of a medication. By inserting a modified form of remdesivir into this lipid prodrug, and then attaching it to an enzyme called a lipid-phosphate (which acts as a delivery system, bringing along the remdesivir prodrug combo), they were able to create an oral form of remdesivir.

Dr. Aaron Carlin, a co-first author of the study, says they were trying to create a hybrid version of the medication that would work equally well regardless of the tissue it interacted with.

“The metabolism of remdesivir is complex, which may lead to variable antiviral activity in different cell types. In contrast, these lipid-modified compounds are designed to be activated in a simple uniform manner leading to consistent antiviral activity across many cell types.”

When they tested the lipid prodrugs in animal models and human cells they found they were effective against COVID-19 in different cell types, including the liver. They are now working on further developing and testing the lipid prodrug to make sure it’s safe for people and that it can live up to their hopes of reducing the severity of COVID-19 infections and speed up recovery.

The study is published in the journal Antimicrobial Agents and Chemotherapy.

CIRM funded researchers discover link between Alzheimer’s gene and COVID-19

Dr. Yanhong Shi (left) and Dr. Vaithilingaraja Arumugaswami (right)

All this month we are using our blog and social media to highlight a new chapter in CIRM’s life, thanks to the voters approving Proposition 14. We are looking back at what we have done since we were created in 2004, and also looking forward to the future. Today we focus on groundbreaking CIRM funded research related to COVID-19 that was recently published.

It’s been almost a year since the world started hearing about SARS-CoV-2, the virus that causes COVID-19.  In our minds, the pandemic has felt like an eternity, but scientists are still discovering new things about how the virus works and if genetics might play a role in the severity of the virus.  One population study found that people who have ApoE4, a gene type that has been found to increase the risk of developing Alzheimer’s, had higher rates of severe COVID-19 and hospitalizations.

It is this interesting observation that led to important findings of a study funded by two CIRM awards ($7.4M grant and $250K grant) and conducted by Dr. Yanhong Shi at City of Hope and co-led by Dr. Vaithilingaraja Arumugaswami, a member of the UCLA Broad Stem Cell Research Center.  The team found that the same gene that increases the risk for Alzheimer’s disease can increase the susceptibility and severity of COVID-19.

At the beginning of the study, the team was interested in the connection between SARS-CoV-2 and its effect on the brain.  Due to the fact that patients typically lose their sense of taste and smell, the team theorized that there was an underlying neurological effect of the virus.  

The team first created neurons and astrocytes.  Neurons are cells that function as the basic working unit of the brain and astrocytes provide support to them.  The neurons and astrocytes were generated from induced pluripotent stem cells (iPSCs), which are a kind of stem cell that can become virtually any type of cell and can be created by “reprogramming” the skin cells of patients.  The newly created neurons and astrocytes were then infected with SARS-CoV-2 and it was found that they were susceptible to infection.

Next, the team used iPSCs to create brain organoids, which are 3D models that mimic certain features of the human brain.  They were able to create two different organoid models: one that contained astrocytes and one without them.  They infected both brain organoid types with the virus and discovered that those with astrocytes boosted SARS-CoV-2 infection in the brain model. 

The team then decided to further study the effects of ApoE4 on susceptibility to SARS-CoV-2.  They did this by generating neurons from iPSCs “reprogrammed” from the cells of an Alzheimer’s patient.  Because the iPSCs were derived from an Alzheimer’s patient, they contained ApoE4.  Using gene editing, the team modified some of the ApoE4 iPSCs created so that they contained ApoE3, which is a gene type considered neutral.  The ApoE3 and ApoE4 iPSCs were then used to generate neurons and astrocytes.

The results were astounding.  The ApoE4 neurons and astrocytes both showed a higher susceptibility to SARS-CoV-2 infection in comparison to the ApoE3 neurons and astrocytes.  Moreover, while the virus caused damage to both ApoE3 and ApoE4 neurons, it appeared to have a slightly more severe effect on ApoE4 neurons and a much more severe effect on ApoE4 astrocytes compared to ApoE3 neurons and astrocytes. 

“Our study provides a causal link between the Alzheimer’s disease risk factor ApoE4 and COVID-19 and explains why some (e.g. ApoE4 carriers) but not all COVID-19 patients exhibit neurological manifestations” says Dr. Shi. “Understanding how risk factors for neurodegenerative diseases impact COVID-19 susceptibility and severity will help us to better cope with COVID-19 and its potential long-term effects in different patient populations.”

In the last part of the study, the researchers tested to see if the antiviral drug remdesivir inhibits virus infection in neurons and astrocytes.  They discovered that the drug was able to successfully reduce the viral level in astrocytes and prevent cell death.  For neurons, it was able to rescue them from steadily losing their function and even dying. 

The team says that the next steps to build on their findings is to continue studying the effects of the virus and better understand the role of ApoE4 in the brains of people who have COVID-19.  Many people that developed COVID-19 have recovered, but long-term neurological effects such as severe headaches are still being seen months after. 

“COVID-19 is a complex disease, and we are beginning to understand the risk factors involved in the manifestation of the severe form of the disease” says Dr. Arumugaswami.  “Our cell-based study provides possible explanation to why individuals with Alzheimer’s’ disease are at increased risk of developing COVID-19.”

The full results to this study were published in Cell Stem Cell.