A few weeks later, CDI ran another round of experiments that subjected my cells to drugs with known toxic side effects. First came Hismanal, an antihistamine, and Propulsid, a drug to treat gastrointestinal distress. Both medications were pulled from the market in many countries, including the United States, because they were associated with rare but potentially life-threatening heart arrhythmias. “This propensity is due to the unanticipated and unwanted side effect of both drugs blocking and disrupting the normal activity of a specific ion channel in the heart,” said a report e-mailed to me from CDI. “Both drugs had similar effects on David Duncan’s iPS-derived cardiomyocytes: a dose-dependent increase in the duration of the action potential … Prolonged action potential durations are a recognized trigger for cardiac arrhythmia that can result in sudden death.”
For a second round of pharmaceutical testing, the scientists exposed my cells to two cancer drugs: Gleevec, used mostly to treat some forms of leukemia, and Sutent, used to treat tumors in the stomach, bowel, and esophagus. Both drugs have side effects that include damage to the heart, though they remain in use because the diseases they treat are so serious. “In vitro tests on David Duncan’s iPS-derived cardiomyocytes demonstrated that both drugs had adverse effects,” said my report, “and that the Gleevec-mediated effect may have been caused by disrupting mitochondrial function.” Again, the reactions of my cells were not atypical, although the researchers told me that if I had cancer, further testing might turn up specific responses that could help a physician decide which medications were best for me.
Ashley told me that iPS-generated heart cells offer great potential as a way to test cancer treatments. “Chemo drugs are really hard on hearts, and on heart cells,” he said. “If this technology can help, that will be really important.”