A drug developed to fight cancer has cut the risk of death in hospitalised COVID-19 patients by more than 55%, found a recent study after a randomised, multicenter placebo-controlled phase 3 clinical trial.

The study, conducted by Veru, a US-based pharmaceutical company, showed that the drug called Sabizabulin managed to reduce adverse and serious adverse events in the patients, who were at high risk for acute respiratory distress syndrome (ARDS) and death.

"This landmark study published in The New England Journal of Medicine Evidence shows the high consistency of sabizabulin treatment to significantly reduce deaths across patient subgroups regardless of standard of care treatment received, baseline WHO scores, age, comorbidities, vaccination status, COVID-19 variant, or geography," said Mitchell Steiner, co-author of the study and MD, Chairman, President, and Chief Executive Officer of Veru, in a press release.

Veru has also submitted an emergency use authorisation request to the US Food and Drug Administration (FDA) to use Sabizabulin to treat COVID-19.

The COVID-19 pandemic is in its third year. Since 2019, the world has seen more than 556 confirmed covid cases and 6.3 million deaths caused by the virus, according to data provided by Johns Hopkins' COVID-19 dashboard. As many as 11 vaccines have been granted emergency use authorisation by the World Health Organization. A few effective antiviral treatments such as Remdesevir, Paxlovid and Molnupiravir and monoclonal antibodies such as Bebtelovimab have been approved by the FDA. However, none of these drugs are a substitute for vaccination against COVID-19.

While the findings of the recent study are a major feat, some infectious disease specialists have cautioned about certain caveats in the study.

How Sabizabulin Works

Sabizabulin was originally developed by researchers at the University of Tennessee to combat cancer by slowing metastasis (spread of cancer to a different body part from where it started). This drug is mainly used in prostate and breast cancer cases. According to Veru, the drug acts as an antiviral and anti-inflammatory agent.

Dr Lancelot Mark Pinto, consultant pulmonologist and epidemiologist at PD Hinduja Hospital, Mumbai, told FactChecker that cells have microtubules that are critical for the movement of chemicals within the cell that are essential for survival. These microtubules are also important for viruses that hijack the cell and use them to survive and multiply. "Sabizabulin is a microtubule disruptor that interferes with the functioning of microtubules, thereby preventing viral replication, and subsequently arresting the inflammatory cascade associated with viremia that is responsible for the severity of SARS-CoV-2," explained Dr Pinto.

Sabizabulin Against COVID-19: Findings & Caveats

The researchers selected hospitalised patients for the study and included patients who were at a high risk of dying of COVID-19. The patients were allowed to simultaneously take available treatments for COVID-19.

Of the 204 volunteer patients that participated over the course of two months, 134 received Sabizabulin and 70 a placebo. The study found that those in the placebo group had a higher mortality rate (45.1%) compared to those receiving Sabizabulin (20.2%).

Dr Pinto said the sample size in the study could have been bigger to confirm the results. "There was also a high mortality rate (45.1%) among those who did not receive the drug (placebo arm), which seems unusually high, thereby possibly inflating the effect of the drug. We need larger studies to confirm these results," said Dr Pinto.

When asked if the numbers in the study were overestimated, Dr Pinto said that a larger study would have resulted in a more conservative effect, given that the mortality in the placebo group does appear unusually high.

Sabizabulin treatment resulted in a 24.9 percentage point absolute reduction and a 55.2% relative reduction in deaths compared with placebo, the study read. Sabizabulin treatment also resulted in a 43% relative reduction in ICU days, a 49% relative reduction in days on mechanical ventilation, and a 26% relative reduction in days in the hospital versus placebo.

While the results of the study are impressive, there's another caveat that the patients were unvaccinated. "Over half the patients in the study were unvaccinated, and were severely ill. Hence, the results of the study should be extrapolated to similar populations," said the pulmonologist.

Moreover, in the data sharing statement, the authors of the study have not disclosed the data collected in the study. "The authors should also place the data in the open domain, which, when I last checked, was not the case," he added.

The trial was, however, halted by the company because an independent advisory committee found that data had proved the benefits of the drug and further stated that it would be unethical to continue administering critical patients a placebo.

In a statement to The New York Times, Dr David Boulware, an infectious disease expert at the University of Minnesota, said while he recognised the ethical aspects of the trial, a much more modest result could have been seen if the trial had been completed. "Trials which are stopped early routinely overestimate the effect," said Dr Boulware.

The pulmonologist also cautioned against administering the drug to any person regardless of age or comorbidities if it is approved by authorities in the future. Being elderly (over 65 years of age) or young with a documented comorbidity should necessarily be included in the trial and the drug should not be used indiscriminately, or in patients with mild illness, Dr Pinto concluded.