The molecular system that shepherds antibodies from a mother’s milk to her baby’s bloodstream may soon provide a painless alternative to drug injections. Molecules in the lining of a baby’s digestive tract pull antibodies from milk before they’re digested and escort them to the blood. This mechanism also operates in the upper-lung and nasal passages, and it remains active throughout life. Syntonix Pharmaceuticals of Waltham, MA, plans to exploit the pathway by fusing antibodies to drug molecules that are conventionally delivered by injection. Entering the body via an inhaler, nasal spray, or a pill, the fused drug molecule takes the antibody shortcut to the bloodstream, says Alan Bitonti, the company’s vice president for research. Last year, Syntonix began a human trial of a fused version of the red-blood-cell booster erythropoietin; several other fused drugs are in preclinical testing.