The present invention relates to methods of treating a patient who has colorectal cancer and to methods of reducing the likelihood that a patient will develop or experience a recurrence of colorectal cancer. The methods comprise a step of introducing, to the patient, an effective amount of an agent that targets an intestinal H+-coupled di/tripeptide transporter (PepT1). Useful compositions including, for example, the tripeptide KPV, vectors encoding such peptides, and cells (e.g., bacterial cells) including them, are also within the scope of the present invention, as are kits including such compositions.