A new treatment in the fight against breast cancer has excited scientists and offers hope in slowing the progression of the disease, though the drug is still in trials and may be years away from availability.

The Telegraph reports that treatment for women with aggressive HER2-positive breast cancer slowed down the illness by forty percent. Patients who were getting the treatment—an injection of Herceptin with an antibody drug— lived five months longer without their illness getting worse than women who received normal chemotherapy.

Nick Collins, science correspondent for the Telegraph, writes that the new drug “consists of a protein which seeks out tumors and a toxin which is only released once inside cancer cells, reducing the damage to healthy tissue.”

Collins quotes Professor Paul Ellis of Guy’s Hospital in London as telling the Sunday Express, "A drug like this which increases survival with far less side effects is the holy grail of cancer medicine.”