What is the fine-grained topic of the following text: Public-sector research institutions (PSRIs) have performed the upstream, basic research to elucidate the underlying mechanisms and pathways of disease and identify promising points of intervention, whereas corporate researchers have performed the downstream, applied research to discover drugs that can be used to treat diseases and have then carried out the development activities to bring the drugs to market. Only return the topic.
Role of Public-sector research institutions and corporate researchers in drug discovery and development