Beginning November 2017 the NIH plans to publish Parent R01 Clinical Trial Required and NIH Exploratory/Developmental Parent R21 Clinical Trial Required Funding Opportunity Announcements (FOAs). Some NIH Institutes and Centers will join these parent FOAs and others will jointly or alone publish specific Clinical Trials. You will not be able to apply for a Clinical Trial grant unless the FOA states it can be used for Clinical Trials.
Click on the link for more NIH information.
https://grants.nih.gov/grants/guide/notice-files/NOT-OD-18-010.html
https://grants.nih.gov/grants/guide/notice-files/NOT-OD-18-001.html