Roche "armed antibody" shrinks some breast tumors

Roche "armed antibody" shrinks some breast tumors
Thu, May 14, 2009
By Deena Beasley

LOS ANGELES, May 14 (Reuters) - Tumors shrank in a quarter of breast cancer patients treated with an "armed antibody," even though they had stopped responding to the standard formulation of breast cancer drug Herceptin, according to mid-stage trial results released on Thursday.

Genentech, a unit of Roche Holding AG (ROG.VX), is developing the platform, in which an antibody-based drug, such as the company's Herceptin, is used to deliver a toxic chemotherapy compound directly to tumors.

"These results are telling us that studying this type of new, novel medicine, which gives us a new way of delivering chemotherapy to cancer cells, has the potential of being applied to many more tumor types," said Philippe Bishop, head of clinical development for Genentech's Avastin cancer drug.

The Phase 2 trial of 112 patients with advanced breast cancer showed that after a median follow-up of 9.5 months, 25 percent saw their tumors shrink at least 30 percent.

All of the trial participants had been previously treated with Herceptin and 60 percent had also received GlaxoSmithKline PLC's (GSK.L) Tykerb, known generically as lapatinib.

The trial involved a conjugate comprised of Herceptin linked to ImmunoGen Inc's (IMGN.O) cell-killing agent, DM1.

Herceptin, also known as trastuzumab, is designed to target the HER-2 protein, which is generated by between 25 percent and 30 percent of breast cancer patients.

Bishop said Genentech has been able to overcome the limitations of some predecessor antibody products through simplification and better engineering.

Genentech has already launched a Phase 3 trial of T-DM1 in advanced HER-2 positive breast cancer patients and has more than 30 antibody-drug conjugates in development, he said. (Reporting by Deena Beasley, Editing by Maureen Bavdek)