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Exploring Drug Repurposing for COVID-19 Treatment

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Drug screening-High throughput robot
Caption: Robotic technology screening existing drugs for new purposes. Credit: Scripps Research

It usually takes more than a decade to develop a safe, effective anti-viral therapy. But, when it comes to coronavirus disease 2019 (COVID-19), we don’t have that kind of time. One way to speed the process may be to put some old drugs to work against this new disease threat. This is generally referred to as “drug repurposing.”

NIH has been doing everything possible to encourage screens of existing drugs that have been shown safe for human use. In a recent NIH-funded study in the journal Nature, researchers screened a chemical “library” that contained nearly 12,000 existing drug compounds for their potential activity against SARS-CoV-2, the novel coronavirus that causes COVID-19 [1]. The results? In tests in both non-human primate and human cell lines grown in laboratory conditions, 21 of these existing drugs showed potential for repurposing to thwart the novel coronavirus—13 of them at doses that likely could be safely given to people. The majority of these drugs have been tested in clinical trials for use in HIV, autoimmune diseases, osteoporosis, and other conditions.

These latest findings come from an international team led by Sumit Chanda, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA. The researchers took advantage of a small-molecule drug library called ReFRAME [2], which was created in 2018 by Calibr, a non-profit drug discovery division of Scripps Research, La Jolla, CA.

In collaboration with Yuen Kwok-Yung’s team at the University of Hong Kong, the researchers first developed a high-throughput method that enabled them to screen rapidly each of the 11,987 drug compounds in the ReFRAME library for their potential to block SARS-CoV-2 in cells grown in the lab. The first round of testing narrowed the list of possible COVID-19 drugs to about 300. Next, using lower concentrations of the drugs in cells exposed to a second strain of SARS-CoV-2, they further narrowed the list to 100 compounds that could reliably limit growth of the coronavirus by at least 40 percent.

Generally speaking, an effective anti-viral drug is expected to show greater activity as its concentration is increased. So, Chanda’s team then tested those 100 drugs for evidence of such a dose-response relationship. Twenty-one of them passed this test. This group included remdesivir, a drug originally developed for Ebola virus disease and recently authorized by the U.S. Food and Drug Administration (FDA) for emergency use in the treatment of COVID-19. Remdesivir could now be considered a positive control.

These findings raised another intriguing question: Could any of the other drugs with a dose-response relationship work well in combination with remdesivir to block SARS-CoV-2 infection? Indeed, the researchers found that four of them could.

Further study showed that some of the most promising drugs on the list reduced the number of SARS-CoV-2 infected cells by 65 to 85 percent. The most potent of these was apilimod, a drug that has been evaluated in clinical trials for treating Crohn’s disease, rheumatoid arthritis, and other autoimmune conditions. Apilimod is now being evaluated in the clinic for its ability to prevent the progression of COVID-19. Another potential antiviral to emerge from the study is clofazimine, a 70-year old FDA-approved drug that is on the World Health Organization’s list of essential medicines for the treatment of leprosy.

Overall, the findings suggest that there may be quite a few existing drugs and/or experimental drugs fairly far along in the development pipeline that have potential to be repurposed for treating COVID-19. What’s more, some of them might also work well in combination with remdesivir, or perhaps other drugs, as treatment “cocktails,” such as those used to successfully treat HIV and hepatitis C.

This is just one of a wide variety of drug screening efforts that are underway, using different libraries and different assays to detect activity against SARS-CoV-2. The NIH’s National Center for Advancing Translational Sciences has established an open data portal to collect all of these data as quickly and openly as possible. As NIH continues its efforts to use the power of science to end the COVID-19 pandemic, it is critically important that we explore as many avenues as possible for developing diagnostics, treatments, and vaccines.

References:

[1] Discovery of SARS-CoV-2 antiviral drugs through large-scale compound repurposing. Riva L, Yuan S, Yin X, et al. Nature. 2020 Jul 24 [published online ahead of print]

[2] The ReFRAME library as a comprehensive drug repurposing library and its application to the treatment of cryptosporidiosis. Janes J, Young ME, Chen E, et al. Proc Natl Acad Sci USA. 2018;115(42):10750-10755.

Links:

Coronavirus (COVID-19) (NIH)

ReFRAMEdb (Scripps Research, La Jolla, CA)

The Chanda Lab (Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA)

Yuen Kwok-Yung (University of Hong Kong)

OpenData|Covid-19 (National Center for Advancing Translational Sciences/NIH)

NIH Support: National Institute of Allergy and Infectious Diseases; National Institute of General Medical Sciences


Repurposing an “Old” Drug for Alzheimer’s Disease

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Senator Mikulski during her tour of NCATS

Caption: Here I am with Senator Barbara Mikulski (center) and NCATS Director Chris Austin (right). Credit: NIH

Alzheimer’s disease research is among the many areas of biomedical science that Senator Barbara Mikulski has championed during her nearly 40 years on Capitol Hill. And it’s easy to understand why the Senator is concerned: an estimated 5 million Americans age 65 and older have Alzheimer’s disease, and those numbers are expected to rise exponentially as the U.S. population continues to age.

So, I was thrilled to have some encouraging progress to report last week when Senator Mikulski (D-MD) paid a visit to NIH’s National Center for Advancing Translational Sciences (NCATS) in Gaithersburg, MD. After a whirlwind tour of the cutting-edge robotics facility for high throughput screening of small molecules, she joined me and NCATS Director Dr. Chris Austin in announcing that, thanks to an innovative public-private partnership, an experimental drug originally developed to fight cancer is now showing promise against Alzheimer’s disease.


siRNAs: Small Molecules that Pack a Big Punch

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Photo of parkin protein (green) that tags damaged mitochondria (red)

Caption: NIH scientists used RNA interference to find genes that interact with the parkin protein (green), which tags damaged mitochondria (red). Mutations in the parkin gene are linked to Parkinson’s disease and other mitochondrial disorders.
Credit: Richard J. Youle Laboratory, NINDS, NIH

It would be terrific if we could turn off human genes in the laboratory, one at a time, to figure out their exact functions and learn more about how our health is affected when those functions are disrupted. Today, I’m excited to announce the availability of new data that will empower researchers to do just that on a genome-wide scale. As part of a public-private collaboration between the NIH’s National Center for Advancing Translational Sciences (NCATS) and Life Technologies Corporation, researchers now have access to a wealth of information about small interfering RNAs (siRNAs), which are snippets of ribonucleic acid (RNA) with the power to turn off a gene, or reduce its activity—in much the same way that we use a dimmer switch to modulate a light.


Strengthening Clinical/Translational Research in the U.S.

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At NIH, our job—in a nutshell—is to turn discoveries into health. Even if you’ve only read this blog a few times, you know we conduct and support basic science advances, clinical breakthroughs—and everything between. We call that “between” process, “translation.” And it takes sustained creativity, innovation, attention—and collaboration—to do it well.

Which brings me to today’s Institute of Medicine (IOM) Report on NIH’s Clinical and Translational Science Awards (CTSA) program [1].


Making This A Land for You and Me

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Photo of Woody Guthrie and Led Belly walking down a dirt road

Photo from liner notes of the Folkways CD

Today is International Rare Disease Day. In honor of the occasion, I’d like to pay tribute to a few real-life heroes whose struggles have forever changed the landscape of rare disease research.

Folk singer Woody Guthrie is best known for his song, “This Land Is Your Land.” Written more than 70 years ago, “This Land” has taken its place among our nation’s great anthems, setting forth a vision of inclusiveness that has inspired generations of Americans to “sing along.” But the last couple of verses are often omitted. Here’s a version of one of them:

As I was walkin’I saw a sign there
And that sign said
no trespassin’
But on the other side … it didn’t say nothin’!
Now that side was made for you and me!

These verses brought into the foreground those whom society had marginalized. “This Land” reminded us of their existence, challenged us to live up to our ideals—and include all people in our best vision of ourselves.

Woody performing one version of “This Land”:

Even as he was singing about inclusiveness, Woody Guthrie was starting a long battle against a disease that increasingly cast him outside mainstream society: Huntington’s disease. In most cases—and as was indeed the case for Woody—symptoms of Huntington’s disease do not appear until adulthood. Gradually, this rare, inherited neurological disorder seizes control of its sufferer’s body, mind—and even voice. In 1965, 13 years after he was diagnosed, Woody fell mute. He had long since lost his ability to play guitar. Two years later, he died at the age of 55.


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