ImmunoGen ($IMGN), the small drug delivery firm out of Massachusetts, has seen its stock prices climb after partnering with the likes of Roche ($RHHBY) and Eli Lilly ($LLY), trading at as much as $14.50 a share this month. But is the company's $1.2 billion market value unrealistically high? TheStreet's Adam Feuerstein thinks so. Feuerstein wrote that while ImmunoGen may be in line for a big success with the breast cancer drug T-DM1, it's due only a 5% royalty on the drug's sales from Roche's Genentech. Even if the drug is a blockbuster, Feuerstein writes, ImmunoGen won't be living up to its sky-high evaluation. Story