Onetime stem cell stalwart Geron Corp. (GERN -1.07%), which has since reinvented itself as an oncology company, may have just lost its only oncology drug. The stock plunged 60% today after the FDA placed a total clinical hold on imetelstat in both of its phase 2 trials for separate blood cancer indications, because of a low-grade but persistent increase in liver enzymes across all patients in the trial. The FDA needs to know about the reversability and seriousness of these liver toxicity issues before allowing the drug to proceed.

In this video, Motley Fool health-care analyst David Williamson discusses why Geron is dead in the water as long as the FDA hold persists. While there is a possibility that investors could see a nice pop if the FDA does give the all-clear at some point in the future, investing on that thesis is about as risky as it gets. If the FDA nixes imetelstat completely, David says he doesn't see anything here that would keep Geron afloat.

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