Roche's star cancer drug stumbles in study, raising doubts about future

By John MillerZURICH (Reuters) - Roche's Tecentriq immuno-oncology drug failed a late-stage follow-up trial against advanced bladder cancer, the Swiss drugmaker said on Wednesday, raising questions about whether regulators could scale back their approval of the medicine.Roche, the world's biggest maker of cancer drugs, had won fast-track approval last May in the United States for Tecentriq against bladder cancer but full approval hinged on further trials.Roche said a phase III IMvigor211 study t