The Sphinx Project (The Chimaera Chronicles #1) by Kate Hawkings

Not many people can say their entire existence has been one big lab experiment: poked and prodded by scientists, genetically modified to be the best and endure the worst, subjected to daily tests and trials that would kill a normal human. All Michaela wants is her own life, to be able to go to school, flirt with boys, maybe eat ice cream now and then. So when the chance to escape finally comes, Michaela and her sister grab it, taking their friends with them. But they weren't the only ones to find their way out of those labs. Following close behind are another breed of creature, one that doesn't know the difference between right and wrong, who exist only to feed their own hunger. The appearance of a strange boy who seems too much like them to be a coincidence makes things even more confusing. But as the world begins to literally fall apart around them, Michaela must accept his help, especially when she could lose the very thing she holds dearest: her sister.