Methods of assessing or monitoring the effect, efficacy, responsiveness to treatment, and/or determining a dose or dosing regimen of therapeutic agents, such as integrin beta7 antagonists, for the treatment of gastrointestinal inflammatory disorders are provided. In certain aspects, methods of using integrin beta7 subunit-containing receptor occupancy by the integrin beta7 antagonist on colonic lymphocytes as an indicator (“biomarker”) of the effect, efficacy, or responsiveness to treatment, and/or as a means to determine dosing or dosing regimens of therapeutic agents such as beta7 integrin antagonists for the treatment of gastrointestinal inflammatory disorders are provided. In certain aspects, methods of assessing the effect, efficacy, or responsiveness to beta7 integrin antagonist treatment by measuring gene expression levels of one or more integrin receptor ligands, lymphocyte genes, cytokine genes, or the number of alphaE-positive cells in intestinal crypt epithelium are provided.