Abstract: The present disclosure relates to a Co-029 inhibitor for inhibiting the migration of cancer cells which express Co-029. The disclosure relates to a Co-029 inhibitor for the treatment of cancer and/or the prevention of cancer metastasis and pharmaceutical compositions comprising said inhibitor and provides Co-029 antibodies. The disclosure provides a method for predicting the response of a patient afflicted with or susceptible to be afflicted with cancer to a medical treatment with a Co-029 inhibitor, a method for diagnosing a cancer in a patient and a method for predicting the survival in a cancer patient.