The common antibiotic Zithromax received a new warning label from the U.S. Food and Drug Administration indicating it could cause dangerous arrhythmias in people with pre-existing heart conditions. Now, researchers at the Stanford University School of Medicine describe a “clinical trial in a dish” using patient-specific induced pluripotent stem, or iPS, cells to predict whether a drug will dangerously affect the heart’s function. The technique may be more accurate than the current in vitro drug-safety screening assays used by pharmaceutical companies, say the researchers, and may better protect patients from deadly side effects of common medications.
The technique allows scientists for the first time to test drugs directly on cells with mutations that cause hereditary cardiac diseases, rather than on the genetically modified human embryonic kidney cells or the Chinese hamster ovarian cells currently being used to detect cardiac toxicity.
The use of patient-specific iPS cells may help drug designers winnow heart-safe medications from those like the blockbuster anti-inflammatory drug Vioxx, which was withdrawn from the market because of unanticipated adverse cardiovascular events. It may also allow clinicians to identify sub-groups of patients, such as those with certain types of cardiac conditions, who should not be given certain drugs.
“Right now, the first time any drug sees a human heart cell is in a phase-1 clinical trial,” said Andrew Lee, a Stanford medical student and one of three lead authors of the study. “If adverse effects are seen, it can result in patient deaths, as in the case of the anti-inflammatory drug Vioxx or with cisapride, a drug previously used to treat digestive problems in people with diabetes. Right now, there are really no systematic studies to identify those people who are at risk.” Lee works in the laboratory of Joseph Wu, MD, PhD, who co-directs the Stanford Cardiovascular Institute, where the research was conducted.
The researchers anticipate that the technique, if adopted, could save millions of dollars and thousands of lives by streamlining the drug-testing process and increasing its sensitivity.
