Human ESCR Trial Stopped Due to Cysts in Animal Studies

The much vaunted—and now delayed—human trial for Geron’s ESCR product for acute spinal cord injury was stopped because the treatment caused cysts in animals.  From the story:

Animals being tested using Geron Corporation’s treatment for spinal cord injury developed cysts at the injury sites, a finding that led the U.S. FDA to place a clinical hold on a planned human trial of the treatment, the Menlo Park, Calif.-based stem cell firm said on August 27. However, Geron said, the cysts did not spread, did not harm the lab animals, nor did they lead to teratomas, a form of tumor that is usually, but not always, benign. Recent testing of the product showed no cyst development, according to the company.

Hmm.  You know, tumors formed in a child given fetal cell treatments three years after the injection, and so I wonder how long an animal would have to be followed to determine safety.  And we can’t forget that the company apparently has not tested the product in large animals, and so there is some swimming in the dark here. Nevertheless, the FDA did the right thing here in terms of pure safety.