The ongoing debate over the cost of prescription drugs took another twist as U.S. Sen. Bernie Sanders (I-VT.) has asked the U.S. Department of Veterans Affairs to use emergency powers to break - or override - the patents on high-priced hepatitis C medicines sold by several drug makers, including Gilead Sciences.

The new hepatitis C treatments cure more than 90% of those infected and, in the U.S., cost from $63,000 to $94,500, depending upon the drug and regimen, before any discounts. Gilead markets Sovaldi and Harvoni, while...