We applied COVID-KOP to identify possible mechanistic connections between linagliptin and COVID-19 that would support its expected therapeutic effect or identify possible side effects. Using the COVID-KOP user interface, a query is constructed as follows. Individual nodes are placed and linked to specific biomedical objects (such as node n2 being a gene in Fig. 1A). The user can then link these nodes together in any order. In this case study, node n0 is matched to COVID-19; n1 is marked as any phenotypic feature linked to COVID-19; and n2 is any gene related to a phenotypic feature connected to COVID-19. Finally, n2 must also have a connection to the linagliptin.