Researchers are racing to set up clinical trials to evaluate a huge variety of treatments and vaccines for COVID-19. Over the past few weeks, as we began to see a “flattening of the curve” in some places, we also observed the stopping of several COVID-19 clinical trials. Why are these trials being stopped? To date, two reasons for the termination of the clinical trials have surfaced:


1. Lack of patient enrollment: Gilead suspended a remdesivir COVID-19 trial in China, citing a lack of eligible patients for enrollment. The company shut down a phase III clinical trial treating mild to moderate COVID-19 patients with remdesivir. This is the second remdesivir clinical trial to be halted due to lack of patient enrollment in China. However, Gilead’s clinical trials that are testing remdesivir in severe patients in other geographies continue.


2. Safety concerns: A clinical trial in Brazil was stopped after several patients with COVID-19 died while being treated with the malaria drug chloroquine.4 The study had two cohorts being tested: a high-dose and a low-dose group.4 After receiving the drug, 11 patients died from both the high-dose and low-dose chloroquine groups in the first few days.


Similarly, a study in France pulled COVID-19 patients off hydroxychloroquine due to safety concerns.5 Researchers observed abnormal heart rhythms in patients, and physicians worry that the atypical cardiac rhythms could lead to sudden cardiac arrest.


Some have criticized the large number of non-randomized controlled trials (RCTs), suggesting that they may divert potential patients needed to rigorously test new treatments in large RCTs.6 As the number of new cases of COVID-19 continues to decrease in some regions, we may see more trials struggle to meet enrollment targets, and sponsors will have to continue to monitor and adapt their COVID-19 programs.


For additional information about the evolving COVID-19 pipeline, study results and milestones, please visit our visual COVID-19 vaccine and treatment pipeline tracker. Check back weekly as we provide an updated view of the clinical development landscape and advancements in the search for safe and effective tools to fight the COVID-19 pandemic.