Provided herein are compositions, methods and kits for treating inflammatory bowel disease (IBD) such as Crohn's disease and ulcerative colitis in a mammal in need thereof. The method include administering to a subject with IBD a combination therapy containing a therapeutically effective amount of a chemokine receptor 9 (CCR9) inhibitor compound and a therapeutically effective amount of an anti-α4β7 integrin antibody such as vedolizumab. Also provided herein is a kit containing the CCR9 inhibitor compound and anti-α4β7 integrin antibody.