The drug: Trastuzumab-DM1, or T-DM1
The disease: Breast cancer
The developer: Roche
Peak projections: $2 billion-$5 billion

T-DM1's prospects keep shining, with clinical results presented at a recent cancer meeting in Stockholm adding to the resume of a drug that could be destined for stardom. Roche, the largest cancer drug maker in the world, aims to extend the life of its blockbuster franchise for breast cancer drugs with the promising T-DM1. The Swiss drug giant's $2 billion to $5 billion peak sales estimate makes it one of the biggest potential sellers anywhere.

In Stockholm last month, Roche said patients treated with T-DM1 in a Phase II trial lived significantly longer without their breast tumors getting worse and suffered far fewer serious side effects than patients who received the standard combo of Roche's Herceptin and the chemo drug Taxotere. These data added creditability to the underlying technology of the drug, an "armed antibody," which consists of the HER2-targeting antibody Herceptin that attached with a chemical linker to the chemotherapy DM1. This approach could limit damage to non-cancerous tissues observed when chemo drugs are given as stand-alone agents.

After failing to gain FDA approval last year based on promising Phase II data, Roche is building up a Phase III data package, part of which the drugmaker plans to include in a global regulatory submission in 2012. The key Phase III trial in the next submission is expected to be Roche's EMILIA study, which puts T-DM1 to the test as a second-line therapy for HER2-positive breast cancer. The HER2 mutations are drivers in about one in 5 breast cancer cases.  

Waltham, MA-based biotech ImmunoGen ($IMGN), which provides the linker technology that "arms" Herceptin with the chemo drug, also has a lot to gain from an approval of the drug. T-DM1 is the most advanced drug that uses the biotech's linker technology, and the firm is due royalties on potential sales of the treatment.

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