ImmunoGen Inc has regained the development and commercialization rights for cantuzumab mertansine (huC242-DM1), an anticancer product candidate. In 1999, the Company licensed these rights to SmithKline Beecham, which later became GlaxoSmithKline. Cantuzumab mertansine has been studied in Phase I clinical trials and found to be well tolerated. Initial evidence of biological activity also has been reported.

ImmunoGen previously announced that GlaxoSmithKline had notified the Company that advancement of cantuzumab mertansine into Phase II studies was dependent on renegotiation of the product license agreement. Since then, the companies have been in negotiations.

Mitchel Sayare, ImmunoGen Chairman and CEO, commented, "We've determined that it is not in the best interests of ImmunoGen to enter into a revised agreement with GlaxoSmithKline. ImmunoGen has regained all rights that were licensed to GlaxoSmithKline. We're excited about the prospects of licensing cantuzumab mertansine to a new marketing partner that would initiate a broad Phase II program for this important product candidate."

No payments were made by either company for the return of the product rights to ImmunoGen. ImmunoGen holds the Investigational New Drug application (IND) for cantuzumab mertansine and has rights to all clinical data generated in the Phase I studies. The two companies will work together to ensure a smooth transition of all study data.

Cantuzumab mertansine is a Tumor-Activated Prodrug (TAP) compound developed by ImmunoGen. It is composed of the humanized antibody huC242 and the cytotoxic agent DM1. The huC242 antibody binds specifically to the CanAg antigen present in a number of cancers including colorectal, pancreatic, and gastric cancers as well as certain non-small-cell lung cancers. Cantuzumab mertansine is designed to deliver the highly potent cell-killing agent DM1 specifically to cancer cells using the huC242 antibody as a targeting vehicle.