Abstract: 322 | Journal of Molecular Cell Biology (2020), 12(4), 322–325 doi:10.1093/jmcb/mjaa014 Published online April 1, 2020 Application Note Treating COVID-19 with Chloroquine This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons. org/licenses/by-nc/4.0/), which permits noncommercial re-use, distribution, and reproduction in any medium, provided the original work is properly cited. For commercial re-use, please contact journals.permissions@oup.com 2008), and the newly discovered SARSCoV-2 (previously known as 2019-nCoV) (Wang et al., 2020). Therefore, Chloroquine may be repurposed for COVID-19 as an emergency therapy. From January 27, 2020 to February 15, 2020, we initiated a clinical study to evaluate the efficacy and safety of Chloroquine in hospitalized patients with COVID-19. At that time, Lopinavir/Ritonavir, a protease inhibitor treatment combination for HIV infection, had been recommended for treating COVID-19 according to the diagnosis and treatment guidelines of novel coronavirus pneumonia (NCP) (World Health Organization, 2020) by the National Health Commission of the People’s Republic of China. Therefore, we included Lopinavir/Ritonavir treatment as a control group. In our study, efficacy was evaluated by (i) real-time polymerase chain reaction (RT-PCR) for measuring COVID-19 viral RNAs, (ii) lung computerized tomography (CT) for assessing the improvement of NCP, and (iii) length of hospitalization for assessing patient recovery. Safety was evaluated by adverse event monitoring. Here, we report our initial results on Chloroquine therapy of COVID-19 patients. Firstly, among the 82 patients screened, 22 met the enrollment criteria (Figure 1A; Supplementary material). All the 22 patients were tested positive for SARS-CoV-2 by RT-PCR assay before enrollment. Their main symptoms were dry cough, fatigue, and fever, and severe cases were characterized by dyspnea, hypoxemia, or acute respiratory dysfunction. Patients were then randomized into two groups: 10 patients, including 3 severe and 7 moderate cases, were treated with Chloroquine 500 mg orally twice daily for 10 days; 12 patients, including 5 severe and 7 moderate cases, were treated with Lopinavir/Ritonavir 400/100 mg orally twice daily for 10 days. Primary baseline demographic and clinical features of the patients are listed in Table 1, with fairly even matched characteristics between two groups. Secondary baseline information is listed in Supplementary Table S1. We initially relied on RT-PCR to measure virological outcomes and showed that one patient in the Chloroquine group became SARS-CoV-2 negative after treatment for only 2 days (Figure 1B, left panel). There were then steady increases in the number of patients turning negative, cumulating at Day 13 when all of the Chloroquine-treated patients became negative (Figure 1B, left panel; Supplementary Table S2). In comparison, patients in the Lopinavir/Ritonavir group only became SARS-CoV-2 negative after 3 days of dosing, and 11 out of 12 turned negative at Day 14. Comparing to the Lopinavir/Ritonavir group, the percentages of patients who became SARS-CoV-2 negative in the Chloroquine group were slightly higher at Day 7, Day 10, and Day 14 (Supplementary Table S2). These results suggest that Chloroquine has slight advantage over Lopinavir/Ritonavir based on RNA tests. Besides, lung CT is another effective indicator to clinically evaluate..