Drug Repurposing for Prevention and Treatment of COVID-19: A Clinical Landscape

Abstract

SARS-CoV-2, the novel coronavirus strain responsible for the current pandemic of COVID-19, has rendered the entire humanity suffering. Several months have passed since the pandemic has struck. However, the world is still looking for an effective treatment plan to battle the viral infection. The first vaccine just received emergency approval in December 2020 for use in USA and UK. These are excellent news, however, the worldwide distribution of such vaccine, the possibility of virus mutation and the lack of data regarding the long-term effects of such vaccines are a significant concern. In addition, although remdesivir was recently approved by the FDA to be used as a clinical drug against COVID-19, it hasn't stood out yet as a proven form of therapeutics. Such inability to produce a novel therapy has caused enough inconveniences for the affected people worldwide. Repurposing the already available drugs to fight against the virus seems to be a reasonable option amidst such uncertainty. Given the vast collection of potential treatment candidates to be explored against COVID-19, there is a decent chance that a success in this regard will serve the intermediary purpose of clinically treating the infection until a COVID-19 vaccine is widely distributed worldwide and will be able to treat COVID-19 patients that do not adequately respond to vaccines. Such treatments may prove very useful in future coronavirus outbreaks too. Proper research into these repurposing treatments may yield a certain insight into the field of novel treatment production as well. This review study accumulates a relevant set of information about drugs and vaccines against COVID-19, in terms of their repurposing properties and the specific phases of clinical trials they are undergoing across the world. A potential timeline is also suggested to estimate when an effective result can be expected from the ongoing clinical trials for a better anticipation of the drug landscape. This study will hopefully help accelerate investment of resources into development and discovery of drugs and vaccines against the infection.

Keywords: COVID-19; SARS-CoV-2; clinical trial; drug repositioning; phases; therapeutics; vaccine.

Figure 1. Overview of host pathways and viral replication mechanisms of the repurposed therapeutic drugs undergoing clinical trial against COVID-19

Drugs of both biological and chemical origins are shown along with a number of vaccines involved in repurposed applications in context of their respective pathways and mechanisms.

Figure 2. Percentage of chemically derived drugs, biological treatments and combined therapy in current clinical trials for repurposing against COVID-19

The graph has been generated using the Microsoft Excel application.

Figure 3. List of both (A.) biological treatments including vaccines and (B.) chemically derived drugs with their respective clinical trial numbers

Vaccines mentioned with clinical trial numbers include both SARS-CoV-2 vaccines and different other vaccines which are being tested for repurposing purposes. Drugs of chemical nature with most occurrences in clinical trials are listed in orderly fashion. The graphs have been generated using the Microsoft Excel application.

Figure 4. A graphical representation of (A) leading countries and sponsors associated with the clinical trials of the COVID-19 drug candidates and (B) phases and predicted timeline of the clinical trials of the COVID-19 drug candidates

Many countries with at least 10 ongoing clinical trials through different sponsorships are shown by their names. Sponsors are categorized into two distinct groups: industry and others that include universities, organizations, government and government agencies. Different phases of drug trials with respect to specific timelines of potential approval are presented. Some of the drugs are in simultaneous clinical trials of two different phases, whereas the specific phases are not mentioned clearly for some others, hence kept in NA (Not applicable). The graphs have been generated using the Microsoft Excel application.