The endpoint of a clinical trial is an outcome that can be measured to determine whether or not the drug or treatment tested has benefit to patients. This could be an improvement in overall survival (OS), progression-free survival (PFS) or symptoms and side effects. When a trial fails to meet its endpoint, it means that the treatment being studied has not acheived the benefit that researchers were expecting — however this endpoint may be based on information that has changed over the years. So a “failed” trial may still show that a treatment provides some benefits for patients. Take a look at OS, PFS, ORR, etc for other measures of success.