Trials on existing drugs spark fresh hope in fight against Covid-19

As Covid-19 cases surge in parts of the United States with low vaccination rates, the urgent need to prevent patients from flooding already-overburdened hospitals has led to a sharp increase in demand for monoclonal antibodies (mAbs). But, with national stocks rapidly dwindling, some hard-hit states along America’s Gulf Coast have been forced to ration access to treatments.

While not a replacement for vaccines, monoclonal antibodies have proved their therapeutic value in Covid-19 patients by boosting the body’s immune response and improving recovery rates. Studies have shown that some antibody treatments – Regeneron, for instance – can reduce the risk of hospitalization or death by 70 percent. To date, four monoclonal antibody treatments have received FDA Emergency Use Authorization (EUA) for use during the pandemic, with others under consideration. Still, the treatments’ limitations—cost, availability, and the setting in which they must be delivered—underscore the need for a broader array of coronavirus therapies.

Rising demand for Covid therapeutics

A number of politicians in hard-hit states have heralded monoclonal antibodies as a game-changer, and, indeed, their apparent efficiency has served as a boon to medics battling huge rises in Covid-19 cases that are threatening to overwhelm the healthcare system.

More than 20 treatment sites have recently opened in Florida, where over 90 percent of intensive care unit (ICU) beds are occupied. The government has announced the creation of so-called ‘strike teams’ that will target the delivery of mAbs treatments in areas of urgent need.

Capacity has become a limiting factor. Although sites are being expanded to make treatment more accessible, the rapid spread of the Delta variant means that supply is consistently trailing demand in many areas. The rationing of mAbs supplies now occurring in some of America’s hardest-hit areas is a timely reminder that while monoclonal antibodies have shown great promise in the treatment of Covid-19, they’re not a silver bullet – even in wealthier countries like the United States.

Only high-risk adults who test positive for Covid-19 are currently eligible for antibody treatment in the US and there’s a relatively narrow window for delivery via IV infusion in a medical setting. It’s not only drug stocks that are in limited supply: healthcare staff qualified to oversee the time- and resource-intensive mAbs treatments are also thin on the ground. And while delivering monoclonal antibodies can lower the chances of severe illness, theoretically reducing the pressure on hospitals, it also takes staff away from their normal clinical duties, potentially stretching precious healthcare resources even further. Moreover, low- and middle-income countries (LMICs) are likely to face serious financial and logistical difficulties rolling out antibody therapy at any significant scale.

Widening the net

The dream, for both wealthy countries and the developing world, is to find safe and widely available existing drugs that have been approved for other conditions and are found to be effective at treating Covid-19. Repurposing drugs in this way is hardly a new phenomenon, including for the coronavirus: remdesivir was originally developed in response to Ebola but was co-opted to the fight against Covid following clinical trials.

There are any number of promising candidates currently under evaluation. California-based Rigel Pharmaceuticals’ oral spleen tyrosine kinase (STK) inhibitor fostamatinib, marketed as Tavalisse, proved safe in Phase II trials recently published in the Clinical Infectious Diseases journal. What’s more, in the double-blind, randomized, placebo-controlled Phase II trial, Tavalisse sparked a clinically significant improvement in hospitalized Covid patients. Treatment with the drug appeared to halve the occurrence of serious adverse events in those already receiving oxygen therapy and reduce the median length of ICU stay from 7 days in the placebo group to only 3 in the group treated with fostamatinib. The drug is now being evaluated in several Phase III trials, including one supported by $16.5 million from the U.S. Department of Defense.

Other potential treatments are also being investigated. A recent pilot study by scientists at the Spanish National Center for Cardiovascular Research suggested that the affordable hypertension drug metoprolol might alleviate lung inflammation in patients with severe Covid. Researchers found that the beta blocker effectively combated inflammation and fluid accumulation in the lungs, improving the clinical outcomes in Covid-19 patients exhibiting acute respiratory distress syndrome (ARDS).

Immunosuppressant drug tocilizumab, originally developed for rheumatoid arthritis patients, has also shown promising results for those critically ill with Covid-19 in early findings from REMAP-CAP. A limited trial showed that giving tocilizumab to people hospitalised with severe Covid-19 was linked to a 14 percent reduction in mortality risk.

Meanwhile, just days ago, a study by University of Georgia researchers was published in Nature’s Scientific Reports suggesting that probenecid, an FDA-approved medication for gout, might have broad antiviral properties – not only against Covid, but against other diseases such as the flu. The medicine has shown indications that it might prove useful not only in patients who have already contracted Covid-19 but also as a prophylactic to help protect vulnerable patients from falling ill.

Living with Covid-19

Thanks to the speed at which vaccines are being rolled out across the world, deaths from the coronavirus are slowing in many countries. However, as new Covid-19 variants continue to emerge, it’s unlikely that vaccinations alone will be able to entirely prevent infections. With new treatments taking years to develop, it makes sense to investigate repurposing existing medications to find more cost- and time-effective ways of helping patients to recover from the virus.

Monoclonal antibody treatments offer one line of defence but others – including anti-viral therapies, anti-inflammatory drugs and anti-clotting compounds – may prove essential in helping healthcare providers better manage and mitigate the potentially severe complications caused by Covid-19.

This article does not necessarily reflect the opinions of the editors or the management of EconoTimes