My initial thoughts are that this split two-trial design allows...

My initial thoughts are that this split two-trial design allows Trial 2 to be open label.

With some google is my friend research, it also saves money since RAC doesn't pay for the patients in the Synthetic Control Arm ... smart!!!!

https://www.statnews.com/2019/02/05/synthetic-control-arms-clinical-trials/

Extract:

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The benefits to the pharmaceutical industry are clear. By reducing or eliminating the need to enroll control participants, a synthetic control arm can increase efficiency, reduce delays, lower trial costs, and speed lifesaving therapies to market. Imagine a trial that needs to include have 500 participants in the treatment arm in order to demonstrate the effectiveness of a new therapy. Instead of having to recruit 1,000 patients — 500 for the active arm, 500 for the control arm — only 500 participants need to be recruited when a synthetic control arm is employed.​

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