An experimental treatment, called T-DM1, is a harbinger of a new class of cancer drugs that may be more effective and less toxic than many existing treatments. These laboratory-produced molecules mimic the antibodies made by a person’s immune system to fight infection. But instead of attacking pathogens these antibodies attach to specific proteins on the surface of cancer cells. “It’s almost like we’re masking the chemotherapy,” said Dr. Edith Perez, a breast cancer specialist at the Mayo Clinic in Jacksonville, Fla.
