CHICAGO – Immunogen Inc. shares (NASDAQ:IMGN) shot up 72 percent to close at $15.44 Monday on news that about half of the heavily pre-treated patients in a phase I study of the company's single agent ovarian cancer therapy candidate demonstrated overall response (ORR), besting the 15 percent to 20 percent response rate typically seen in platinum-resistant ovarian cancer patients and giving the company confidence to plan a possible pivotal phase II trial for late 2015.