If more than half a century ago, science looked expectantly at the potential of chemotherapy to combat cancer; or 15 years ago, oncologists did the same with immunotherapy, which energized the immune system's own defenses to attack tumor cells; now the spotlight has turned to an innovative treatment that is reaping promising results: antibodydrug conjugates (ADCs), treatments that function like a Trojan horse, delivering chemotherapy to the interior of tumor cells to destroy them.