Abstract: Annals of Oncology Letters to the Editor investigation, including antiviral drugs, we suggest that convalescent plasma could be useful in patients with COVID19 infection and concurrent persistent B-cell immunodeficiency; we will consider this approach for our patient.3e5 N. Issa1*, F. Lacassin2 & F. Camou1 Medical Intensive Care and Infectious Diseases Unit, SaintAndre Hospital, CHU Bordeaux, Bordeaux; 2 Infectious Disease Department, Mont de Marsan Hospital, Mont de Marsan, France (*E-mail: nahema.issa@chu-bordeaux.fr). 1 Available online 29 June 2020 © 2020 European Society for Medical Oncology. Published by Elsevier Ltd. All rights reserved. https://doi.org/10.1016/j.annonc.2020.06.016 FUNDING None declared. DISCLOSURE The authors have declared no conflicts of interest. REFERENCES 1. Berlin DA, Gulick RM, Martinez FJ. Severe Covid-19. N Engl J Med. 2020. https://doi.org/10.1056/NEJMcp2009575. 2. Gao Y, Chen Y, Liu M, Shi S, Tian J. Impacts of immunosuppression and immunodeficiency on COVID-19: a systematic review and meta-analysis. J Infect. 2020;81(2):e93ee95. 3. Valk SJ, Piechotta V, Chai KL, et al. Convalescent plasma or hyperimmune immunoglobulin for people with COVID-19: a rapid review. Cochrane Database Syst Rev. 2020;5:CD013600. 4. Franchini M. Why should we use convalescent plasma for COVID-19? Eur J Intern Med. 2020;77:150e151. 5. Pinto D, Park YJ, Beltramello M, et al. Cross-neutralization of SARS-CoV-2 by a human monoclonal SARS-CoV antibody. Nature. 2020;583(7815): 290e295. Does androgen deprivation therapy protect against severe complications from COVID-19? Currently, there is a paucity of effective treatments to address the remarkably high morbidity and mortality associated with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) coronavirus disease-19 (COVID-19). This letter highlights a potential therapeutic strategy based on known biology of SARS-CoV-2 cellular entry and replication. SARS-CoV-2 relies on surface expression of angiotensinconverting enzyme 2 (ACE2) and transmembrane serine proteases 2 (TMPRSS2) for cellular entry and replication in the respiratory epithelium.1,2 In in vitro and mouse models, Volume 31 - Issue 10 - 2020 TMPRSS2 inhibition limits respiratory cell damage and reduces severity of infection.1,3 TMPRSS2 is commonly expressed in prostate cancer cells and is known to be regulated by androgens.4 Hence, androgen deprivation therapy (ADT) may theoretically reduce TMPRSS2 expression limiting SARS-CoV-2 cellular entry and preventing severe complications from COVID-19. In fact, a recent report from Alimonti and colleagues demonstrated a lower rate of infection in prostate cancer patients on ADT, compared with those not on ADT.5 Herein, we report our observational study of all patients in a single New York City health system with COVID-19 and prostate cancer to determine the impact of ADT on COVID-19 clinical outcomes. To our best knowledge, this is the largest study to report severity of COVID-19 in patients receiving ADT. This study was approved by the Mount Sinai School of Medicine Institutional Review Board. We identified all Mount Sinai Health System (MSHS) patients with prostate cancer and SARS-CoV-2 viral detection by PCR (based on testing within and outside MSHS) from 1 March 2020 to 4 June 2020. We collected clinical information including demographics, medical history, and medications including ADT use. ADT use was defined as a gonadotropin-releasing hormone (GnRH) analog or..