Research Roundup: Access to experimental COVID-19 drug paused, WHO to launch coronavirus drug trial, and Takeda's dengue vaccine shows promise in clinical trials
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Due to overwhelming demand, Gilead Sciences has paused granting patients access to remdesivir, an experimental drug which up until now has been used under a “compassionate use” policy against COVID-19—the disease caused by the novel coronavirus. In a statement, the company said it is focused on processing previously approved requests and establishing a new system that allows patients to get the drug in a similar time frame to what it would have taken to work through the requests it has already received. The company will make exceptions for pregnant women and children under the age of 18, as well as those with confirmed cases of COVID-19 who are experiencing “severe manifestations” of the disease. Gilead noted that, in recent weeks, there has been an “exponential increase” in requests for compassionate use of remdesivir due to the spread of COVID-19 in the United States and Europe, which has flooded the treatment access system which was never intended for use in response to a pandemic. Remdesivir is currently being studied in five large clinical trials, two of which could yield results in early April.
The World Health Organization (WHO) has announced it will launch a multi-arm, multi-country clinical trial, known as the SOLIDARITY trial, for potential coronavirus therapies. The trial will test four drugs or drug combinations already licensed and used for other illnesses as part of a global effort to identify treatments for COVID-19. The four therapies include the antiviral drug remdesivir; a combination of two HIV drugs, lopinavir and ritonavir; lopinavir and ritonavir plus interferon beta; and the antimalarial drug chloroquine—all of which have shown some effectiveness against the novel coronavirus either in vitro and/or animal studies. These therapies will be compared to the standard of care—the regular support hospitals treating patients currently use, such as supplementary oxygen. Ten countries have already indicated they will take part in the trial. WHO launched a similar trial in the Democratic Republic of Congo in November 2018 to test four therapies against Ebola.
Phase 2 and 3 clinical trials of Takeda’s tetravalent dengue vaccine candidate showed that it is safe, produces immunity in children, and protects against the disease—regardless of previous exposure to different strains of the virus—according to studies published in The Lancet. In the phase 3 trial, researchers found an overall vaccine effectiveness of 80.2 percent in the first 11 months and 73.3 percent in the first 17 months. Takeda’s dengue vaccine candidate is only the second dengue vaccine to enter clinical trials, following Sanofi Pasteur's Dengvaxia. Sanofi’s vaccine was 56–61 percent effective in preventing dengue in children, but it was tied to severe illness in some individuals vaccinated without having prior exposure to infection. Dengvaxia was approved by the US Food and Drug Administration last May, but with caveats due to potential adverse effects. Takeda is conducting clinical trials in dengue endemic countries before seeking regulatory approval.