Cancer doctor Cassian Yee remembers how in 2010 he was called to Los Angeles to meet the Internet billionaire Sean Parker. Parker wanted Yee to help the Hollywood producer Laura Ziskin, then fighting breast cancer, with an immune-cell treatment never before used to treat that condition. “We’ll give you whatever you need, we’ll put you on an island to do it,” Parker told Yee. A few weeks later a very big check arrived by mail to buy some crucial equipment.