Understanding Clinical Trial Terminology: What is a Long-Term Extension or Open-Label Extension Study?

August 19th, 2020

Clinical trials are important research studies that are conducted to test potential new medicines in people after earlier stages of research have been successfully completed. Clinical trials typically move forward in a series from early-stage, small-scale Phase 1 studies to late-stage, large-scale, Phase 3 studies. These studies could be double-blind in which case the trial participant and the clinical trial site staff do not know the treatment assigned or open-label in which case all involved know what the trial participant is treated with.

There is another type of study that exists between the traditional clinical trial phases and application for approval of a new medication: an open-label extension (OLE) study, sometimes also called a long-term extension study.

An OLE study is a clinical trial that typically enrolls participants of a previous clinical trial and is designed to gather the long-term safety and tolerability data on a potential new medicine beyond the time period of the main study.

Participants are usually informed at the time they agree to participate in the main study that, depending on the outcome, they may have the option to enroll in an extension study after completion.

In the main trial, patients may or may not receive the medication being tested, but in the OLE all study participants receive the medication being tested. The duration of extension studies after the end of the original clinical trial can vary.

OLE studies can play a useful role in drug development as companies gather data and advance potential new medicines toward approval, while also giving patients free access to a new medication in development that they are already familiar with after participating in a previous clinical trial.




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