The engineered antibody also appears to improve insulin sensitivity, which could fight type 2 diabetes, and it decreases levels of triglycerides.
Yang Li, scientific director at Amgen, Inc., Thousand Oaks, CA, and senior author stated that, "The results we describe in animal models are profound and very encouraging." "While we're excited about these findings, we're still evaluating the results."
The current study began by looking at a molecule called fibroblast growth factor 21 (FGF21). This molecule has garnered a lot of research interest because it appears to have many positive effects on obesity and type 2 diabetes according to the study.
In the body, FGF21 is induced during fasting or starvation. Scientists are still trying to understand how FGF21 causes beneficial changes, but suspect it may activate the less common but more metabolically active brown fat.
Developing FGF21 into a treatment is challenging, because the molecule isn't stable in the blood. That means any treatment developed from the natural protein might require frequent injections, he said.
In the current research, Li and his colleagues took a different approach. Instead of looking at FGF21, the researchers attempted to find other, more stable ways to activate the same pathways activated by FGF21.
The researchers engineered an alternative in the lab -- an antibody called mimAb1. They tested the new antibody on 10 obese monkeys and compared them to another 10 obese monkeys in a control group.
The monkeys in the treatment group received two injections -- one the first week and another the third week. Five to six weeks after the first injection the monkeys had lost 10 percent of their body weight. The reductions in body weight were maintained at least nine weeks after the second injection.
What's more, the weight loss appeared to occur even without a significant reduction in calories, Li said. In addition to weight loss and improved insulin sensitivity, the animals' abdominal circumference and BMI decreased.
"When we tested mimAb1 in the animal model, we saw a lot of beneficial changes. The results were quite encouraging," Li said. He added that they didn't see any significant side effects, including low blood sugar levels.
He said it's also possible that although this particular treatment may not be the answer for human obesity or diabetes, it may provide more clues into the mechanisms behind these conditions.
Science Translational Medicine, Nov. 28, 2012