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TMPRSS2

ACTIV Update: Making Major Strides in COVID-19 Therapeutic Development

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NIH ACTIV
Credit: NIH

Right now, many U.S. hospitals are stretched to the limit trying to help people battling serious cases of COVID-19. But as traumatic as this experience still is for patients and their loved ones, the chances of surviving COVID-19 have in fact significantly improved in the year since the start of the pandemic.

This improvement stems from several factors, including the FDA’s emergency use authorization (EUA) of a number of therapies found to be safe and effective for COVID-19. These include drugs that you may have heard about on the news: remdesivir (an antiviral), dexamethasone (a steroid), and monoclonal antibodies from the companies Eli Lilly and Regeneron.

Yet the quest to save more lives from COVID-19 isn’t even close to being finished, and researchers continue to work intensively to develop new and better treatments. A leader in this critical effort is NIH’s Accelerating COVID-19 Therapeutic Interventions and Vaccines (ACTIV) initiative, a public-private partnership involving 20 biopharmaceutical companies, academic experts, and multiple federal agencies.

ACTIV was founded last April to accelerate drug research that typically requires more than a decade of clinical ups and downs to develop a safe, effective therapy. And ACTIV has indeed moved at unprecedented speed since its launch. Cutting through the usual red tape and working with an intense sense of purpose, the partnership took a mere matter of weeks to set up its first four clinical trials. Beyond the agents mentioned above that have already been granted an EUA, ACTIV is testing 15 additional potential agents, with several of these already demonstrating promising results.

Here’s how ACTIV works. The program relies on four expert “working groups” with specific charges:

Preclinical Working Group: Shares standardized preclinical evaluation resources and accelerate testing of candidate therapies and vaccines for clinical trials.

Therapeutics Clinical Working Group: Prioritizes therapeutic agents for testing within an adaptive master protocol strategy for clinical research.

Clinical Trial Capacity Working Group: Has developed and organized an inventory of clinical trial capacity that can serve as potential settings in which to implement effective COVID-19 clinical trials.

Vaccines Working Group: Accelerates the evaluation of vaccine candidates.

To give you just one example of how much these expert bodies have accomplished in record time, the Therapeutics Clinical Working Group got to work immediately evaluating some 400 candidate therapeutics using multiple publicly available information sources. These candidates included antivirals, host-targeted immune modulators, monoclonal antibodies (mAb), and symptomatic/supportive agents including anticoagulants. To follow up on even more new leads, the working group launched a COVID-19 Clinical & Preclinical Candidate Compound Portal, which remains open for submissions of therapeutic ideas and data.

All the candidate agents have been prioritized using rigorous scoring and assessment criteria. What’s more, the working group simultaneously developed master protocols appropriate for each of the drug classes selected and patient populations: outpatient, inpatient, or convalescent.

Through the coordinated efforts of all the working groups, here’s where we stand with the ACTIV trials:

ACTIV-1: A large-scale Phase 3 trial is enrolling hospitalized adults to test the safety and effectiveness of three medicines (cenicriviroc, abatacept, and infliximab). They are called immune modulators because they help to minimize the effects of an overactive immune response in some COVID-19 patients. This response, called a “cytokine storm,” can lead to acute respiratory distress syndrome, multiple organ failure, and other life-threatening complications.

ACTIV-2: A Phase 2/3 trial is enrolling adults with COVID-19 who are not hospitalized to evaluate the safety of multiple monoclonal antibodies (Lilly’s LY-CoV555, Brii Biosciences’s BRII-196 and BRII-198, and AstraZeneca’s AZD7442) used to block or neutralize the SARS-CoV-2 virus. The Lilly monoclonal antibody LY-CoV555 received an EUA for high risk non-hospitalized patients on November 9, 2020 and ACTIV-2 continued to test the agent in an open label study to further determine safety and efficacy in outpatients. Another arm of this trial has just started, testing inhaled, easy-to-administer interferon beta-1a treatment in adults with mild-to-moderate COVID-19 who are not hospitalized. An additional arm will test the drug camostat mesilate, a protease inhibitor that can block the TMPRSS2 host protein that is necessary for viral entry into human cells.

ACTIV-3: This Phase 3 trial is enrolling hospitalized adults with COVID-19. This study primarily aims to evaluate safety and to understand if monoclonal antibodies (AstraZeneca’s AZD7442, BRII-196 and BRII-198, and the VIR-7831 from GSK/Vir Biotechnology) and potentially other types of therapeutics can reduce time to recovery. It also aims to understand a treatment’s effect on extrapulmonary complications and respiratory dysfunction. Lilly’s monoclonal antibody LY-CoV555 was one of the first agents to be tested in this clinical trial and it was determined to not show the same benefits seen in outpatients.

ACTIV-4: This trial aims to determine if various types of blood thinners, including apixaban, aspirin, and both unfractionated (UF) and low molecular weight (LMW) heparin, can treat adults diagnosed with COVID-19 and prevent life-threatening blood clots from forming. There are actually three Phase 3 trials included in ACTIV-4. One is enrolling people diagnosed with COVID-19 but who are not hospitalized; a second is enrolling patients who are hospitalized; and a third is enrolling people who are recovering from COVID-19. ACTIV-4 has already shown that full doses of heparin blood thinners are safe and effective for moderately ill hospitalized patients.

ACTIV-5: This is a Phase 2 trial testing newly identified agents that might have a major benefit to hospitalized patients with COVID-19, but that need further “proof of concept” testing before they move into a registrational Phase 3 trial. (In fact, another name for this trial is the “Big Effect Trial”.) It is testing medicines previously developed for other conditions that might be beneficial in treatment of COVID-19. The first two agents being tested are risankizumab (the result of a collaboration between Boehringer-Ingelheim), which is already FDA-approved to treat plaque psoriasis, and lenzilumab, which is under development by Humanigen to treat patients experiencing cytokine storm as part of cancer therapy.

In addition to trials conducted under the ACTIV partnership, NIH has prioritized and tested additional therapeutics in “ACTIV-associated trials.” These are NIH-funded, randomized, placebo-controlled clinical trials with one or more industry partners. Here’s a table with a comprehensive list.

Looking a bit further down the road, we also seek to develop orally administered drugs that would potentially block the replication ability of SARS-CoV-2, the coronavirus that causes COVID-19, in the earliest stages of infection. One goal would be to develop an antiviral medication for SARS-CoV-2 that acts similarly to oseltamivir phosphate (Tamiflu®), a drug used to shorten the course of the flu in people who’ve had symptoms for less than two days and to prevent the flu in asymptomatic people who may have been exposed to the influenza virus. Yet another major long-term effort of NIH and its partners will be to develop safe and effective antiviral medications that work against all coronaviruses, even those with variant genomes. (And, yes, such drugs might even cure the common cold!)

So, while our ACTIV partners and many other researchers around the globe continue to harness the power of science to end the devastating COVID-19 pandemic as soon as possible, we must also consider the lessons learned this past year, in order to prepare ourselves to respond more swiftly to future outbreaks of coronaviruses and other infectious disease threats. Our work is clearly a marathon, not a sprint.

Links:

Accelerating COVID-19 Therapeutic Interventions and Vaccines (ACTIV) (NIH)

COVID-19 Research (NIH)

Combat COVID (U.S. Department of Health and Human Services, Washington, D.C.)

Pull Up a Chair with Dr. Freire: The COVID Conversations (Foundation for the National Institutes of Health, Bethesda, MD)

SARS-COV-2 Antiviral Therapeutics Summit Report, November 2020 (NIH)


The Prime Cellular Targets for the Novel Coronavirus

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Credit: NIH

There’s still a lot to learn about SARS-CoV-2, the novel coronavirus that causes COVID-19. But it has been remarkable and gratifying to watch researchers from around the world pull together and share their time, expertise, and hard-earned data in the urgent quest to control this devastating virus.

That collaborative spirit was on full display in a recent study that characterized the specific human cells that SARS-CoV-2 likely singles out for infection [1]. This information can now be used to study precisely how each cell type interacts with the virus. It might ultimately help to explain why some people are more susceptible to SARS-CoV-2 than others, and how exactly to target the virus with drugs, immunotherapies, and vaccines to prevent or treat infections.

This work was driven by the mostly shuttered labs of Alex K. Shalek, Massachusetts Institute of Technology, Ragon Institute of MGH, MIT, and Harvard, and Broad Institute of MIT and Harvard, Cambridge; and Jose Ordovas-Montanes at Boston Children’s Hospital. In the end, it brought together (if only remotely) dozens of their colleagues in the Human Cell Atlas Lung Biological Network and others across the U.S., Europe, and South Africa.

The project began when Shalek, Ordovas-Montanes, and others read that before infecting human cells, SARS-CoV-2 docks on a protein receptor called angiotensin-converting enzyme 2 (ACE2). This enzyme plays a role in helping the body maintain blood pressure and fluid balance.

The group was intrigued, especially when they also learned about a second enzyme that the virus uses to enter cells. This enzyme goes by the long acronym TMPRSS2, and it gets “tricked” into priming the spike proteins that cover SARS-CoV-2 to attack the cell. It’s the combination of these two proteins that provide a welcome mat for the virus.

Shalek, Ordovas-Montanes, and an international team including graduate students, post-docs, staff scientists, and principal investigators decided to dig a little deeper to find out precisely where in the body one finds cells that express this gene combination. Their curiosity took them to the wealth of data they and others had generated from model organisms and humans, the latter as part of the Human Cell Atlas. This collaborative international project is producing a comprehensive reference map of all human cells. For its first draft, the Human Cell Atlas aims to gather information on at least 10 billion cells.

To gather this information, the project relies, in part, on relatively new capabilities in sequencing the RNA of individual cells. Keep in mind that every cell in the body has essentially the same DNA genome. But different cells use different programs to decide which genes to turn on—expressing those as RNA molecules that can be translated into protein. The single-cell analysis of RNA allows them to characterize the gene expression and activities within each and every unique cell type. Based on what was known about the virus and the symptoms of COVID-19, the team focused their attention on the hundreds of cell types they identified in the lungs, nasal passages, and intestines.

As reported in Cell, by filtering through the data to identify cells that express ACE2 and TMPRSS2, the researchers narrowed the list of cell types in the nasal passages down to the mucus-producing goblet secretory cells. In the lung, evidence for activity of these two genes turned up in cells called type II pneumocytes, which line small air sacs known as alveoli and help to keep them open. In the intestine, it was the absorptive enterocytes, which play an important role in the body’s ability to take in nutrients.

The data also turned up another unexpected and potentially important connection. In these cells of interest, all of which are found in epithelial tissues that cover or line body surfaces, the ACE2 gene appeared to ramp up its activity in concert with other genes known to respond to interferon, a protein that the body makes in response to viral infections.

To dig further in the lab, the researchers treated cultured cells that line airways in the lungs with interferon. And indeed, the treatment increased ACE2 expression.

Earlier studies have suggested that ACE2 helps the lungs to tolerate damage. Completely missed was its connection to the interferon response. The researchers now suspect that’s because it hadn’t been studied in these specific human epithelial cells before.

The discovery suggests that SARS-CoV-2 and potentially other coronaviruses that rely on ACE2 may take advantage of the immune system’s natural defenses. When the body responds to the infection by producing more interferon, that in turn results in production of more ACE2, enhancing the ability of the virus to attach more readily to lung cells. While much more work is needed, the finding indicates that any potential use of interferon as a treatment to fight COVID-19 will require careful monitoring to determine if and when it might help patients.

It’s clear that these new findings, from data that weren’t originally generated with COVID-19 in mind, contained several potentially important new leads. This is another demonstration of the value of basic science. We can also rest assured that, with the outpouring of effort from members of the scientific community around the globe to meet this new challenge, progress along these and many other fronts will continue at a remarkable pace.

Reference:

[1] SARS-CoV-2 receptor ACE2 is an interferon-stimulated gene in human airway epithelial cells and is detected in specific cell subsets across tissues. Ziegler, CGK et al. Cell. April 20, 2020.

Links:

Coronaviruses (National Institute of Allergy and Infectious Diseases/NIH)

Human Cell Atlas (Broad Institute, Cambridge, MA)

Shalek Lab (Harvard Medical School and Massachusetts Institute of Technology, Cambridge)

Ordovas-Montanes Lab (Boston Children’s Hospital, MA)

NIH Support: National Institute of Allergy and Infectious Diseases; National Institute of General Medical Sciences; National Heart, Lung, and Blood Institute