Monoclonal antibody (mAb) technology is an excellent tool for the discovery of overexpressed cell surface tumour antigens and the development of targeting agents. Here, we report the development of two novel mAbs against CFPAC-1 human pancreatic cancer cells. Using ELISA, flow cytometry, immunoprecipitation, mass spectrometry, Western blot and immunohistochemistry, we found that the target antigens recognised by the two novel mAbs KU44.22B and KU44.13A, are integrin α3 and CD26 respectively, with high levels of expression in human pancreatic and other cancer cell lines and human pancreatic cancer tissue microarrays. Treatment with naked anti-CD26 mAb KU44.13A did not have any effect on the growth and migration of cancer cells nor did it induce receptor downregulation. In contrast, treatment with anti-integrin α3 mAb KU44.22B inhibited growth in vitro of Capan-2 cells, increased migration of BxPC-3 and CFPAC-1 cells and induced antibody internalisation. Both novel mAbs are capable of detecting their target antigens by immunohistochemistry but not by Western blot. These antibodies are excellent tools for studying the role of integrin α3 and CD26 in the complex biology of pancreatic cancer, their prognostic and predictive values and the therapeutic potential of their humanised and/or conjugated versions in patients whose tumours overexpress integrin α3 or CD26. Pancreatic cancer remains one of the deadliest cancer types. In 2018, there were an estimated 458,918 new cases of pancreatic cancer, and 432,242 deaths as a result of pancreatic cancer in 185 countries worldwide 1,2. Pancreatic cancer is predicted to become the second leading cause of cancer death after lung cancer, within the next decade in Western countries 3. At present, the only curative treatment for patients with pancreatic cancer is surgery. However, only a minority of patients are eligible for resection and disease recurrence is a frequent event in many such patients. Historically, gemcitabine-based therapy has been the mainstay for treatment of pancreatic cancer 4. More recently the combination of gemcitabine plus capecitabine has been regarded as the new standard of care in the adjuvant setting 5. Patients with metastatic disease are treated with either FOLFIRINOX or gemcitabine plus nab-paclitaxel as first-line in patients with good performance status 6,7. In order to reduce the dismal pancreatic cancer mortality rates, it is essential to discover novel biomarkers for use in the early detection of pancreatic cancer, to discover novel therapeutic targets and to develop novel and more effective therapeutic agents 8,9. Monoclonal antibodies (mAbs) are excellent tools for the discovery of novel overexpressed cell surface antigens and their specific targeting for diagnostic and therapeutic purposes 10,11. To date, 36 mAbs have been approved for cancer treatment in the U.S. and/or European Union, although none for pancreatic cancer yet 12,13. As tumour heterogeneity has been reported both between (i.e. inter-tumour heterogeneity)