If he runs away, ignore it. It seems like he is doing this for attention. He's thinking he can bite and then look at the fun game he gets to play! Mommy chases him!
When Layla was a puppy, she acted like this too. If she ran away I would turn my back on her and not give her the attention she wanted, so I wasn't enforcing the behaviour. I know those puppy teeth hurt! But if you give him a stern NO and stop playing when he bites, he'll eventually understand that this isn't the right way to get attention.