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Parkinson's Study Evokes Discussion on Controlled Trials

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Thirty-five patients received the cell transplant while 36 had sham surgery. After 12 months, the investigators found no significant difference in the motor scores of the two groups, with both improving approximately 21 percent.

Both Nature commentaries noted that the placebo effect in Parkinson's studies can be quite pronounced. Katsnelson pointed out that patients' expectations that they will benefit from a treatment can induce the release of dopamine, so there is a physiologic basis for the placebo effect in these patients. Cenci and Widner also addressed the need for all cell-based therapies to have adequate proof of mechanism of action and functional integration of the transplants in pre-clinical models.

Both commentaries likewise discussed the risk of these invasive therapies as well as the somewhat lower risk of sham surgery, along with the need to proceed cautiously while continuing to move cell transplantation into clinical trials.

— Compiled from CIRM President's Update